Keywords: Genetic biocontrol
Prairie grower groups fund research projects targeting canola diseases
35513Ian MacKay, Oyen Echo, 2026-03-17 08:56:22.
Three projects intended to deal with the canola disease verticillium stripe stand out among 11 research programs that a prairie growers consortium is funding this year. Leaders of the canola agronomic research program have chosen projects that they feel are “key to advancing canola productivity and mitigating production threats,” a statement said. The organization includes SaskOilseeds and similar Manitoba and Alberta grower groups, which together are spending over $2.4 million. Results Driven Agriculture Research in Alberta is supplying over $1 million and the Western Grains Research Foundation will chip in $495,000 to bring the total planned expenditure to over $4 million. “The genetic improvement and disease risks facing canola production need to be researched to find solutions,” said Laura Reiter of Radisson, who chairs the Western Grains Research Foundation. “As capacity among public research institutions decreases, grower-led investment isn't just an option anymore, it’s critical to the longevity of our industry,” said Cheryl Westman of Vermilion, who chairs Alberta Canola’s research program. A University of Calgary scientist heads a project titled “Discovering the verticillium longisporum genetic determinants of virulence,” a University of Manitoba scientist aims to test “biocontrol-based strategies” to deal with verticillium stripe in canola and another researcher from that university will use “genetic and molecular approaches” to increase canola’s resistance to verticillium stripe.
Editorial Overview – Insect Genomics (2026): enhancing public health, food security, and biodiversity through genetic biocontrol.
35506Yoosook Lee, Omar S. Akbari, Current Opinion in Insect Science, 2026-03-13 09:43:24.
Genetic biocontrol is a form of biological control in which genetic variants or genetically modified forms of the target species act to reduce or eliminate the target species. In entomology, target species include agricultural pests and vector species that transmit pathogens to human, animal, or plant systems. Examples include the Anopheles mosquito gene drive system to reduce or replace malaria vectors in Africa, the use of Wolbachia symbiont induced cytoplasmic incompatibility in Culex mosquitoes to project Hawaiian native birds from avian malaria related deaths, and the use of CRISPR to generate sterile males at a scale useful for suppressing pests of fruit crops. The widespread availability of robust transgenic technologies combined with new RNA-guided DNA endonuclease-based genome manipulation technologies and platforms and advances in synthetic biology are fueling the development of genetic biocontrol technologies and systems for combating arthropods that contribute to food insecurity, pathogen- and parasite-transmission, and invasive arthropods that threaten biodiversity. Heretofore a niche area of genetic biocontrol now commands great interest and an ever-growing number of applications.
Feral rabbit numbers are booming, so do myxomatosis and calicivirus still work, and what’s next for biocontrol?
35522Belinda Smith, ABC News, 2026-03-12 09:20:38.
If you've noticed more feral rabbits around than usual, you're right. Much of Australia is experiencing a bunny boom, driven by consecutive years of good breeding conditions. But with an estimated 200 million feral European rabbits (Oryctolagus cuniculus) currently hopping around the continent, you might also have wondered if the viruses that kept their numbers down in the past — myxoma virus and a calicivirus that causes rabbit haemorrhagic disease — still work. Heidi Kleinert, national feral rabbit management coordinator at the Centre for Invasive Species Solutions, says ideally Australia needs to develop and release a new biocontrol every 10 to 15 years to keep rabbit numbers as low as possible. "It takes time to find another effective virus that we know is targeted specifically to rabbits, and we know is proven and tested and has approval from government organisations," Ms Kleinert says. "Across Australia, we're seeing more rabbits in peri-urban and urban areas. That's why we need that continuous pipeline of biological control, because in these areas we can't use bait and toxins close to domestic housing and domestic pets." So how do myxoma and rabbit haemorrhagic disease viruses work, and what goes into finding the next bunny biocontrol weapon?
Comparison of single-cell sequencing technologies for allele-specific expression analysis in rabbit spermatids
35482Elena Smertina, Madi Rutherford, Brendan Hosking, et al., Genomics, 2026-03-05 08:26:37.
Gene drives are transmission distorters that can transmit specific alleles to >90% of the progeny, e.g., the naturally occurring t-haplotype in mice. For invasive pest species, there is interest in co-opting naturally occurring gene drives. It is unknown whether similar natural gene drives exist in the European rabbit, one of the most detrimental pest species in Australia. Here, we analysed the allele-specific expression (ASE) in rabbit spermatids to identify candidate genes for future investigation in genetic biocontrol applications. We utilised short-read and long-read technologies and performed a comparative analysis. Illumina sequencing was deemed unsuitable, whereas both long-read sequencing platforms demonstrated a similar performance. The SPINK2 gene that plays an important role in fertility, consistently showed ASE towards one of the alleles in all samples. Furthermore, two kinases were found to display a bimodal allele expression. Future work is warranted to assess suitability of these genes for genetic biocontrol applications.
Biocontrol practitioners’ perspectives on emerging genetic-based technologies for weed management
35412Rafter, M.A., Kumaran, N., Brookes, D.R. et al., BioControl, 2026-01-31 16:43:25.
Weed biocontrol researchers have been at the forefront of developing management solutions for invasive weeds for over 100 years and have a unique perspective to offer on the emerging field of genetic-based technologies such as gene drive and RNAi. As part of the XVI International Symposium on Biological Control of Weeds in May 2023 we conducted a focus group discussion workshop to explore biocontrol practitioners’ perspectives related to: (1) Genetic-based control technologies, and the factors influencing support (or not) for their application to weed management, especially weed biocontrol, (2) perceived opportunities to apply genetic-based control tools to enhance or complement weed biocontrol, focusing on whether/how genetic tools can be applied to fundamentally change the practice of weed biocontrol, and (3) genetic-based control in weed management and how it can operate within the Access and Benefit Sharing regulatory landscape. We analyse the perspectives of biocontrol scientists from the workshop and discuss the prospects and challenges of integrating novel genetic-based control tools with weed biocontrol.
The Genomic Arms Race in Mosquito-Borne Diseases: Integrating Entomopathogenic Fungi, Gene Drive, and Symbiont Technologies for Sustainable Vector Control
35503Rajendran Yamini, Pagalahalli Sankaran Shanmugam, Marimuthu Murugan, et al., J Pure Appl Microbiol., 20:53-65. 2026-01-20 09:32:56.
Mosquito-borne diseases such as malaria, dengue, Zika, chikungunya, and lymphatic filariasis continue to impose enormous health and economic burdens worldwide. The traditional reliance on chemical insecticides has been undermined by the rapid evolution of resistance, ecological concerns, and declining efficacy. Next-generation biocontrol strategies are framed within the concept of a “genomic arms race” between mosquitoes, pathogens, and microbial agents. Entomopathogenic fungi are eco-friendly bioinsecticides with demonstrated efficacy in laboratory, semi-field, and transgenic applications. Symbiont-based approaches, particularly those involving Wolbachia, have been evaluated for their ability to reduce vector competence and spread through populations. Parallel advances in CRISPR-based gene drive technologies have provided transformative tools for population suppression and modification, although their deployment is limited by ethical, ecological, and regulatory concerns. An integrated vector management (IVM) framework combining fungi, gene drives, and symbiont-based tools is proposed as the most promising approach for sustainable mosquito management. This multipronged strategy has the potential to reduce disease transmission, delay resistance development, and minimize ecological disruption, paving the way for resilient, eco-friendly solutions against vector-borne diseases.
Behavior modification in fruit flies through male annihilation technique: field applications, olfactory mechanisms, and future directions
35329Liu, Wei; Zhang, Sijia; Wang, Guirong, Entomologia Generalis, 45:1565 - 1576. 2026-01-06 14:51:47.
The male annihilation technique (MAT), as a method of insect behavior manipulation, is an environmentally friendly approach that has been successfully applied in over 150 fruit fly eradication programs worldwide. Despite their effectiveness in integrated pest management programs, concerns have long persisted about the safety of the primarily used male lures – particularly regarding the potential toxicity of methyl eugenol (ME). In this review, we propose a novel attractant screening and validation system for the future improvement of male lures, based on recent advancements in functional genomics and genetic manipulation technologies achieved in tephritid fruit flies. This system is built upon our knowledge of tephritid fruit flies’ core olfactory signal transduction pathway (“Male lures → Odorant receptors → Odorant receptor neurons → Glomerulus”). The working pipeline is centered around a transgenic Bactrocera strain with labeled male lure-responsive olfactory receptor neurons (ORNs) as the key targets. Electrophysiological responses and calcium activity serve as the readouts, while the decision criteria focus on increased intensity, stability, and specificity of neural activation induced by candidate compounds. This pipeline, compared to traditional behavior-first methods, enables the efficient screening of computationally identified candidate compounds and provides a foundation for evaluating their field stability and safety. More importantly, it represents a shift from empirical, field-based optimization to a molecularly guided, receptor-based design framework, advancing the development of enhanced male lure solutions for future applications in insect behavior manipulation.
Genetic Biocontrol Strategy Considerations for Mosquito Control in the Pacific Island Countries and Territories
35315Adam E. Vorsino, Tim Harvey-Samuel, Limb K. Hapairai, et al., Current Opinion in Insect Science, 2026-01-05 10:49:54.
Mosquito-borne diseases pose an existential threat to the health, economies, and unique ecosystems of Pacific Island Countries and Territories (PICTs). The remoteness of these islands, combined with the presence of highly competent mosquito vectors, complicates disease surveillance and vector control efforts. In response, the PICTs have become a focal point for the development and application of Genetic BioControl (GBC) technologies designed to break vector-borne disease transmission cycles. However, the application of GBC tools in this region warrants careful consideration of its unique history, including a legacy of colonialism, and challenges associated with logistic hurdles. Through meaningful community engagement and authentic collaborations, drawing from local knowledge, and building local capacity, the sustainable, efficient and effective deployment of GBC tools may be achieved.
Integrating mosquito genomics into simulation modeling: Opportunities for better-informed biocontrol
35282Gordana Rašić, John M. Marshall, Current Opinion in Insect Science, 2025-11-03 11:25:51.
Mosquito-borne diseases remain a major global health burden, and novel biocontrol tools are quickly advancing from the laboratory to the field. Mathematical models play a central role in evaluating these interventions, yet their predictive accuracy depends on robust parameterization. Population genomics presents a powerful opportunity to address this challenge. Here, we review progress at the interface between mosquito genomics and biocontrol modeling, highlighting how genomic data have informed our understanding of mosquito population structure, standing genetic variation at gene drive target sites, and sources of resurgence for suppressed populations. We also discuss frontiers, including new approaches to quantifying gene flow, mating behaviors, and inbreeding depression, all of which shape intervention outcomes. By tapping this potential to better quantify our understanding of mosquito ecology, modelers can develop context-specific models with better predictive accuracy, supporting efficacy and risk assessment, design of field trials and interventions, and promotion of regulation and public trust.
The nanosd integral gene drive enables population modification of the malaria vector Anopheles gambiae
35269Pei-Shi Yen, Sebald A N R Verkuijl, Paolo Capriotti, et al., G3 Genes|Genomes|Genetics, 2025-11-02 17:38:52.
The modification of mosquito populations at scale through CRISPR-Cas9-mediated homing gene drives is a promising route for malaria vector control. Integral gene drives (IGDs) are designed to utilise the regulatory sequences of endogenous genes to reduce the size of the modification required for nuclease and effector expression. In this study, we describe the creation and characterisation of the nanosd IGD, which targets and is inserted into the nanos gene of the malaria vector Anopheles gambiae, and show that it achieves high rates of gene drive (98.4% in females, 99.5% in males). We find that homozygous nanosd females but not males show impaired fecundity and exhibit variable degrees of ovary underdevelopment. Transcriptomic analysis of ovaries points to decreased transcript levels of the nanos gene when harbouring Cas9 and changes to other fertility-related genes. As a minimal genetic modification, nanosd does not induce widespread transcriptomic perturbations that would affect vector competence, and we show that its susceptibility to Plasmodium spp. and O’nyong nyong virus infection remains similar to wild-type mosquitoes. Importantly, we find that nanosd propagates efficiently in caged mosquito populations and is maintained as a source of Cas9 after the emergence of drive-resistant alleles, whilst also mobilising a non-autonomous antiparasitic effector modification. The nanosd gene drive shows promise as a genetic tool for malaria vector control via population modification, and we outline steps towards its further optimisation.
Selection, counterselection, and conditional gene expression for genetic biocontrol of insects
35249Melanie Hempel, Zhijian Tu, Insect Science, 2025-10-16 09:29:04.
Genetic biocontrol methods are species-specific ways to suppress or modify pest insect populations to mitigate their economic or health impact. Successful genetic biocontrol often requires mass releases of only males of the target species. Reliable and cost-effective sex separation is a major bottleneck to the implementation of genetic biocontrol of many important species of agricultural and medical importance. Conditional selection is critical to resolving this major challenge. A diverse array of tools, such as the temperature-sensitive systems, the Gal4/UAS, QF/QUAS, and Tet-on/off bipartite systems, and the photoactivatable systems, have been established in various insect species. In this review, we focus on how various means of conditional expression have been used to achieve sex separation. We also describe other means of selection and counterselection to achieve sex separation without conditional gene expression. By providing examples across many species and discussing the strengths and weaknesses of each method, we hope to facilitate the design and application of conditional systems to improve genetic biocontrol of insect pests.
Cattle Q&A with Brinda Dass, GeneConvene Global Collaborative
35243Tyrell Marchant, Progressive Cattle, 2025-10-15 08:41:35.
What factors have led to the northward spread of New World screwworm (NWS) over the past year after so many decades of successful eradication in Mexico and the U.S.? DASS: The northward spread of NWS after decades of eradication reflects a convergence of biological, environmental and programmatic factors. Climate change and increasing temperatures have created favorable conditions for pupal survival and year-round reproduction, enabling rapid reinvasion from subtropical regions. NWS biology – especially females’ ability to lay multiple waves of eggs in wounds – allows populations to surge quickly even from small footholds. High-density livestock practices and insufficient inspection of animal trade further accelerate spread, with smuggling through the Darién Gap undermining surveillance. Wildlife, pets and humans act as reservoirs, compounding detection challenges. Sterile insect technique (SIT), historically successful, has been overwhelmed: Production of sterile flies cannot match population growth, forcing control lines northward. Budget constraints, political disputes and reduced funding have further weakened monitoring and response systems. Together, these dynamics explain how a long-maintained eradication barrier collapsed, allowing NWS to expand northward at alarming speed.
Estimated cost and operational structure of pgSIT malaria vector control programs in selected West African countries
35203William A.C. Gendron, Robyn Raban, Agastya Mondal, et al., Scientific African, 29. 2025-09-30 15:35:38.
Malaria control has primarily been achieved through vector control, but current methods are insufficient to achieve elimination. Precision guided sterile insect technique (pgSIT) is a mosquito suppression technique that generates sterile male mosquitoes for mass release. Our previous studies showed that this intervention is expected to be highly cost-effective in a malaria endemic region of West Africa, but these estimates used only 15-31% capacity for sex sorting, which is the limiting production step and a primary cost. We, therefore, determined the most cost efficient facility size by calculating the cost per million Anopheles gambiae suppressed as the facility was scaled up to suppress more mosquitoes. We developed an optimized facility size per 9.2 million mosquitoes suppressed, which can be a framework for scaling and increases the cost effectiveness of this intervention. The development of this intervention can potentially interrupt malaria transmission, strengthen local public health institutions, create manufacturing capacity, provide local jobs, and enhance regional health security capabilities that are more resilient to disruptions in supply chains and malaria investment.
Leveraging Sex Determination Systems for Genetic Biocontrol of Dipteran Pests
35178Maxwell J. Scott, Zhijian Tu, Current Opinion in Insect Science, 2025-09-26 14:24:25.
Genetic biocontrol is an increasingly important way to suppress insect pest populations and to mitigate their economic and health impact. One key advantage is that it is species-specific as it relies on mating of released males with wild females to either suppress or modify populations. The latter is through rendering females incompetent at disease transmission. Sex separation is critical to ensure the efficiency of these control programs, and it is essential in the case of vector control to avoid releasing females that can transmit pathogens. Modern genetic methods provide the opportunity to target or manipulate components of the sex determination systems to facilitate genetic biocontrol with new means to effectively accomplish sex-specific selection, lethality, or sterility. For example, sex-specific splicing elements in genes in the sex determination pathway are used to produce sex-specific markers. Sex-linked recessive lethal alleles are used to differentially eliminate the transgene-marked sex chromosome from males to produce non-transgenic males. Knocking out or knocking down sex-specific isoforms of genes in the sex determination pathway is employed to confer female-specific lethality or sterility. Sex determination pathways and sex chromosomes are also targeted for gene drives that suppress pest populations by introducing extreme sex ratio biases. Here we review these and other recent advances on the genetic technologies for pest control that have benefited from knowledge of sex determination systems in Diptera.
Heterogeneity in inhibition of genetically diverse dengue virus strains by Wolbachia
35165Afeez Sodeinde, Emilie Finch, Ke Li, et al., bioRxiv, 2025-09-26 13:29:40.
The release of Aedes aegypti mosquitoes transinfected with the virus-inhibiting Wolbachia bacterium has the potential to reduce the burden caused by dengue virus (DENV). However, the robustness of this control strategy across the wide genetic diversity of DENV remains unknown. Here, we systematically tested two commonly used Wolbachia strains (wAlbB and wMelM) for their ability to inhibit 60 genetically diverse DENV isolates spanning all four serotypes. We found stronger inhibition by wMelM (median relative dissemination: 0.04) than wAlbB (median relative dissemination: 0.19). Furthermore, while we found substantial heterogeneity in inhibition across DENV isolates, we found that more DENV-3 isolates were weakly inhibited (median relative dissemination: 0.47 for wAlbB and 0.39 for wMelM) compared to the other serotypes (median relative disseminations: 0.10-0.18 for wAlbB and 0-0.11 for wMelM). Using transmission dynamic models, we further showed that differential Wolbachia inhibition results in increased probability of reemergence, particularly in high transmission intensity settings, with strong selection for DENV strains that have higher relative dissemination in mosquitoes. Our work highlights the importance of considering DENV genetic diversity, including the long-term risk of selection, in Wolbachia-based control interventions.
Wolbachia Infection in Iranian Malaria Vectors: Prevalence and Biocontrol Implications
35124Shahin Saeedi, Fateh Karimian, Seyed Hassan Moosa-Kazemi, et al., Tropical Medicine & International health, 2025-09-08 08:50:24.
Wolbachia-based vector control is an emerging tool in malaria prevention research. This study evaluates Wolbachia infection in Iranian mosquitoes, focusing on seven known malaria vectors. Mosquitoes were collected from nine provinces of Iran (2016–2019), and Wolbachia infection status was analysed via PCR targeting eight genes: wsp, gatB, ftsZ, dnaA, groEL, gltA, CoxA and fbpA. We examined 1094 specimens from seven malaria vectors (Anopheles stephensi Liston, 1901; Anopheles culicifacies s.l. James, 1901; Anopheles fluviatilis s.l. James, 1902; Anopheles maculipennis s.l. Meigen, 1818; Anopheles sacharovi Favr, 1903; Anopheles dthali Patton, 1905; Anopheles superpictus s.l. Grassi, 1899), four non-malaria vectors (Anopheles mongolensis Linton, Lee and Curtis, 2005; Anopheles hyrcanus Pallas, 1771; Anopheles claviger Meigen, 1804; Anopheles turkhudi Liston, 1901) and three Culex species (Culex pipiens Linnaeus, 1758; Culex perexiguus Theobald, 1903; Culex theileri Theobald, 1903). PCR revealed Wolbachia DNA exclusively in An. dthali and Culex species, with infection rates of 73.4% for An. dthali and 77.78%–96.77% for Culex, notably higher in males. Wolbachia was detected in all regions except one in the north. Phylogenetic analysis revealed Wolbachia strains in An. dthali and Culex belong to supergroup B, closely related to strains in An. moucheti and An. demeilloni. This suggests broader applications for biocontrol strategies. The high Wolbachia prevalence in An. dthali is promising for malaria prevention. Future research should confirm cytoplasmic incompatibility and explore wAdth's potential to block malaria transmission.
Development and evaluation of pupal color-based genetic sexing strains in Anastrepha obliqua
35116Daisy P. Cárdenas-Enríquez, Víctor García-Martínez, Jorge Ibáñez-Palacios, et al., Insect Science, 2025-09-08 08:23:07.
Anastrepha obliqua, a neotropical pest widely distributed in the Americas, attacks mango and other tropical fruits. In Mexico, it is controlled through integrated pest management, using the Sterile Insect Technique (SIT) as a main component. The applicability of SIT is significantly improved with the use of genetic sexing strains (GSS) that allow the possibility to release exclusively sterile males, the primary component of the technique. This study reports the isolation and characterization of two pupal mutations: black pupae (bp) and sphere pupae (sp), allowing for the first time the development of a genetic sexing system based on pupal color in this species. Inheritance analyses from reciprocal crosses between wild-type and mutant individuals showed F2 phenotypic segregation consistent with a recessive Mendelian inheritance pattern, and linkage analysis indicated that the bp and sp loci are in separate chromosomes. Using the bp mutation, two GSS were developed through gamma irradiation [T(Y;bp+)/bp-22](GSS-22) and ethyl methanesulfonate treatment [T(Y;bp+)/bp-354](GSS-354). Both GSS exhibited sex-specific pupal differentiation but displayed a high frequency of recombinants. Despite an initial reduction in biological fitness, GSS-22 demonstrated greater genetic stability and a lower frequency of recombinants than GSS-354. Discrepancies between cytogenetic and genomic data, particularly regarding the localization of the gene responsible for the black pupae phenotype, underscore the need to integrate polytene chromosome and genomic analyses to characterize these translocations and improve GSS stability precisely. These results represent a breakthrough in the creation of genetic tools for the management of A. obliqua control.
Genomic Insights into Wolbachia Strain wCin2USA1 Reveal Promising Cytoplasmic Incompatibility Potential and Next-Generation Dengue Biocontrol
35098Istiaque Zaeem, Nurnabi Azad Jewel, Mohimenul Haque Rolin, et al., bioRxiv, 2025-09-01 19:59:21.
Dengue fever is one of the fastest-growing mosquito-borne diseases in the world, causing illness and economic challenges in many countries. Current mosquito control methods, such as insecticides, are often costly, less effective over time, and harmful to the environment. An alternative approach uses naturally occurring bacteria called Wolbachia, which live inside insects. When certain Wolbachia strains are introduced into mosquitoes, they can reduce the insects’ ability to spread viruses like dengue. In our study, we compared the genetic makeup of several Wolbachia strains to identify new candidates that may work better for controlling dengue. We discovered that a strain called wCin2USA1 has strong potential because it shares important features with two strains already used successfully, while also having unique advantages. These include genes that help prevent mosquitoes from reproducing normally when carrying different Wolbachia strains, which can reduce mosquito populations. Our findings suggest that wCin2USA1 could be developed as a new, environmentally friendly tool to help reduce dengue transmission.
Genetic control strategies for population suppression in the Anopheles gambiae complex: a review of current technologies
35055Alekos Simoni, Ignacio Tolosana, Federica Bernardini, Current Opinion in Insect Science, 2025-08-25 20:42:10.
Malaria continues to pose a critical public health threat, with mosquitoes from the Anopheles gambiae complex acting as the main vectors of the disease in sub-Saharan Africa, where approximately 95% of malaria-related deaths occur. Despite significant advancements in vector control, such as insecticide-treated bed nets and indoor spraying, the effectiveness of these interventions is increasingly compromised by various challenges, including rising levels of insecticide and pathogen resistance, mosquito behavioural adaptations, and persistent funding gaps. In this context, genetic vector control strategies have shown considerable promise, primarily based on findings from controlled laboratory studies. This review explores the development of these genetic approaches within the Anopheles gambiae complex and outlines future directions for their advancement and potential integration into malaria control efforts.
The buzz stops here
35057Bill Gates, Gates Notes, 2025-08-19 20:44:24.
I've been working on malaria for over two decades. I’ve talked with researchers in labs and parents who’ve lost children to a mosquito bite. I’ve seen promising new tools and surprising setbacks. But I’ve rarely been as excited about a new innovation as I am about this one. In a lab in Tanzania, researchers are studying something incredible: a mosquito that can’t give you malaria. It looks and behaves like any other mosquito. It flies, bites, and breeds. But what it doesn’t do is transmit one of the deadliest diseases on the planet—which means it could save hundreds of thousands of lives a year. This mosquito was developed in 2023 by a team of African scientists at the Ifakara Health Institute in partnership with Imperial College London. It’s the first transgenic mosquito ever created on African soil—meaning that scientists have made a small, targeted change to its DNA. It was both a major scientific milestone and a major moment of African leadership in the global health space. The project is called Transmission Zero, and its goal is as ambitious as its name: to eliminate malaria not by killing mosquitoes, but by making them unable to transmit it to humans.
How population control of pests is modulated by density dependence: The perspective of genetic biocontrol
34993Cole D. Butler, Alun L. Lloyd, Journal of Theoretical Biology, 2025-07-30 11:07:06.
Managing pest species relies critically on mechanisms that regulate population dynamics, particularly those factors that change with population size. These density-dependent factors can help or hinder control efforts and are especially relevant considering recent advances in genetic techniques that allow for precise manipulation of the timing and sex-specificity of population suppression. Despite this importance, density dependence is often poorly characterized owing to limited data and an incomplete understanding of developmental ecology. To address this issue, we construct and analyze a mathematical model of a pest population with a general control under a wide range of density dependence scenarios. Using this model, we investigate how control performance is affected by the strength of density dependence. By modifying the timing and sex-specificity of the control, we tailor our analysis to simulate different pest control strategies, including conventional and genetic biocontrol methods. We pay particular attention to the latter as case studies by extending the baseline model to include genetic dynamics. Finally, we clarify past work on the dynamics of mechanistic models with density dependence. We find substantial differences in control performance for differing strengths of density dependence, with populations exhibiting strong density dependence being most resilient to suppression. However, these results change with the size and timing of the control load, as well as the target sex. Interestingly, we also find that the strength of density dependence affects population invasion by certain genetic biocontrol strategies. While the model is parameterized using the life history traits of the yellow fever mosquito, Aedes aegypti, the principles developed here apply to many pest species. We conclude by discussing what this means for pest population suppression moving forward.
Coproducing a Technology Readiness Level framework for non-persistent genetic biocontrol of aquatic invasive species
34984Julie Badger, Rex Alirigia, Isabel Ameli, et al, Journal of Environmental Management, 391. 2025-07-24 10:00:28.
Developing and implementing novel pest control technologies requires coordination and communication between technology developers, funding agencies, federal and state regulators, and early technology adopters. Efficient communication is particularly important for first-in-class technologies. Misunderstandings or lack of communication may hinder social engagement, jeopardize regulatory approval, decrease utility of the technology, deter public adoption, or compromise risk mitigation approaches. We, a team of diverse stakeholders in aquatic invasive species (AIS) control, here propose a shared language for discussing the development of non-persistent genetic biocontrol methods. Specifically, we adapted the existing Technology Readiness Level framework to apply to the development of non-persistent genetic biocontrol for invasive Cyprinus carpio (common carp) as a model case. The result of this effort is a tool for designing responsible technology development of a promising new class of pest management tools.
A genetic tweak could prevent mosquitoes from transmitting malaria
34987Jonathan Lambert, NPR, 2025-07-23 10:40:28.
Each year, 263 million people get malaria. But from the parasite's perspective, infecting humans is harder than you might think, and requires completing an epic journey within the tiny body of a mosquito. First, the mosquito must suck the blood of an individual infected with malaria — bringing the Plasmodium parasite into the insect's gut. Then the parasite must travel to the critter's salivary glands, where it's poised to be injected into the mosquito's next victim via a bite. Now a team of researchers have found a way to interrupt this crucial journey. By using gene editing to make a tiny tweak to the mosquito's genome — one that changes just a single amino acid — parasites were largely prevented from reaching their final destination. The change effectively rendered laboratory mosquitoes highly resistant to spreading malaria, researchers report Wednesday in Nature. "The idea that you could change just one amino acid and not have the parasite transmitted is a pretty big deal," says Fred Gould, an entomologist at North Carolina State University who wasn't involved in the study. "It's really exciting." That tiny tweak could be spread through a whole mosquito population using a gene drive, a genetic technology that breaks the normal 50-50 rules of inheritance. Gene drives are sequences of DNA that can be inserted into the genome of an individual and cause a specific mutation or gene to be passed on to virtually all offspring, instead of just 50%.
Changes in the frequency of facultative endosymbionts in insect populations: overview and applications
34922Hoffmann, Ary A.; Cooper, Brandon S., Entomologia Generalis, 45:351-368. 2025-06-23 14:41:27.
Many insect endosymbionts are facultative from the host perspective, and their population frequencies across time and space will depend on their transmission fidelity and effects on host fitness. These effects and transmission rates in turn depend on the environmental and host genetic contexts where the endosymbionts occur. Endosymbionts like Wolbachia and Cardinium affect host reproduction to produce transient or persistent presence/absence polymorphisms, while other endosymbionts like Regiella and Hamiltonella persist through providing host fitness benefits and transmitting horizontally. Evolutionary changes in hosts and endosymbionts affect these impacts and endosymbiont polymorphisms in host populations and host sexes. We review this diversity of endosymbiont-host interactions and their influence on the usefulness of endosymbionts for applied strategies. Current strategies focus on endosymbionts driving useful traits to fixation (particularly Wolbachia suppression of arbovirus transmission by mosquitoes) or endosymbionts suppressing populations due to infected males sterilising females. Transinfected endosymbionts sourced from one species and microinjected into another have proven effective in these Wolbachia-mosquito strategies. Novel strategies involving transinfected Rickettsiella, Regiella and Wolbachia may decrease the impacts of pest invertebrates by suppressing pest numbers, reducing the capacity of vector hosts to transmit plant viral diseases or bolstering the effectiveness of natural enemies. Because many endosymbionts are already present in the environment, their applied use raises fewer safety concerns when compared to genetic modification, as supported by more than 13 years of field experiences with Wolbachia in mosquitoes that have not raised major concerns.
Optimizing larval mass-rearing techniques for Aedes mosquitoes: enhancing production and quality for genetic control strategies
34858Wadaka Mamai, Cécile Brengues, Hamidou Maiga, et al, Parasite, 32. 2025-05-26 20:56:36.
The quantity and quality of laboratory-reared insects are pivotal for the success of any sterile male-release program. Optimizing larval mass-rearing methods to enhance both production and quality in Aedes mosquitoes is essential to meet the growing demand from FAO/IAEA Member States for the sterile insect technique (SIT) as a component of area-wide integrated pest management to control or suppress disease vectors. This study was designed to identify the most effective feeding regime and schedule that maximize pupae production with a single tilt/sorting event and to evaluate an alternative larval-rearing unit. The results demonstrated that ingredient particle size, mosquito strain and feeding regime significantly influenced insect production and quality, underscoring the critical need to account for these factors in mass-rearing operations. A daily feeding regime of 0.17, 0.33, 0.67, 0.67 and 0.5 mg per larva was identified as optimal for both species (Ae. aegypti and Ae. albopictus) achieving up to 80 ± 2.5% male pupae recovery rate when sorted 48 h after the onset of pupation. Production outcomes were not compromised with the exclusion of feeding on Days 2 and 3. Furthermore, under the conditions of this study, the Wolbaki rack (Model WBK-P0003-V2) was shown to be sufficient for mass-rearing Aedes mosquitoes. Finally, a 4-day feeding regime was implemented in a field program on Reunion island, yielding similar pupae recovery rates and contamination as the reference regime, a significant step toward improving cost-efficiency and scaling-up the program. These findings provide valuable information for refining standard operating procedures (SOPs) for mass-rearing, thereby enhancing the efficiency and scalability of SIT programs.
Biased tertiary sex ratios enhance the efficacy of sex-ratio distorting genetic techniques to control invasive species
34843Michael L. Jones, Ronald E. Thresher, Nicholas J. Bax, Journal of Theoretical Biology, 2025-05-12 20:32:40.
Genetic biocontrol strategies are increasingly being developed and tested for reducing the effects of invasive species, and are highly likely to be an important tool of integrated pest management in the future. Included among such strategies are those that distort the sex ratio of the target species. Models used to forecast the efficacy of such strategies generally assume, implicitly, that the tertiary sex ratio of the target population is 50:50. We present evidence that this assumption is important, and that if the tertiary sex ratio is biased towards females, a sex-distorting construct introduced into the population that produces phenotypic males will become fixed at a level determined by the magnitude of the bias, even after further introductions cease. We show, first using a simple logistic population model, and second using a realistic simulation of an important aquatic invasive species – the sea lamprey Petromyzon marinus – how this effect can greatly increase the effectiveness of a sex-distorting construct at population suppression, but also increase the risk of such strategies due to reduced reversibility. We also present evidence that biased tertiary sex ratios might be present in many invasive species, particularly when their population sizes are low relative to environmental carrying capacity.
Optimization of SgRNA expression with RNA pol III regulatory elements in Anopheles stephensi
34801Gonzalez, E., Anderson, M.A.E., Ang, J.X.D. et al., Scientific Reports, 15. 2025-04-23 11:08:06.
Anopheles stephensi, a major Asian malaria vector, is invading Africa and has been implicated in recent outbreaks of urban malaria. Control of this species is key to eliminating malaria in Africa. Genetic control strategies, and CRISPR/Cas9-based gene drives are emerging as promising species-specific, environmentally friendly, scalable, affordable methods for pest control. To implement these strategies, a key parameter to optimize for high efficiency is the spatiotemporal control of Cas9 and the gRNA. Here, we assessed the ability of four RNA Pol III promoters to bias the inheritance of a gene drive element inserted into the cd gene of An. stephensi. We determined the homing efficiency and examined eye phenotype as a proxy for non-homologous end joining (NHEJ) events in somatic tissue. We found all four promoters to be active, with mean inheritance rates up to 99.8%. We found a strong effect of the Cas9-bearing grandparent (grandparent genotype), likely due to maternally deposited Cas9.
Problem formulation for a small-scale field study of non-gene drive, genetically modified, male bias mosquitoes in Burkina Faso
34758Hayes, K. R., & Hosack, G. R., Human and Ecological Risk Assessment: An International Journal, 2025-04-10 09:17:32.
This article documents the problem formulation step of a risk assessment for a proposed small-scale field release in Burkina Faso of genetically modified (GM) An. coluzzii mosquitoes that carry a Paternal Male Bias (PMB) construct. These mosquitoes are part of the pathway developed by Target Malaria to provide a new cost-effective control strategy for malaria vectors in Africa. The problem formulation describes 7 potentially harmful outcomes that might occur through 19 pathways to harm and identifies 22 types of desk-based analysis, 6 laboratory tests, and 5 field observations that can be used to test the risk hypotheses associated with these pathways. The problem formulation forms the basis of a prerelease risk assessment that meets the standards stipulated under the Cartagena Protocol and guidance provided by the World Health Organization, the African Union Development Authority, and the European Food Safety Authority. The Problem Formulation reflects the concerns expressed about the proposed field release by relevant stakeholders, although stated concerns are not always specific enough to be unambiguously associated to a single pathway. The presentation of the pathways to harm emphasizes the types of evidence that supports the steps within each pathway, and so portrays the speculative nature of some pathways.
Bridging the gap: Effective communication strategies for genetic biocontrol technologies
34749Caroline Thuo, African Genetic Biocontrol Consortium, 2025-04-04 10:39:01.
The 2nd Global Congress on Genetic Biocontrol Technologies took place from March 17-20, in Accra, Ghana. The Congress was jointly organized by the African Genetic Biocontrol Consortium, Ghana’s National Biosafety Authority and the Foundation for the National Institutes of Health (FNIH). Held under the theme “Harnessing Genetic Biocontrol Potential Solutions in a Changing Climate”, the event brought together delegates from 19 countries across different continents. It united professionals from diverse disciplines, including scientists, policymakers, regulatory experts and science communicators. The first two days of the congress featured intensive pre-congress workshops and courses focusing on: -Regulatory frameworks and decision-making processes for emerging biotechnologies -Strategic communication of genetic biocontrol technologies -Biosafety and biosecurity protocols for high-containment facilities The pre-congress course on communicating genetic biocontrol technologies attracted mostly journalists and science communicators from the African region. Participants explored topics such as the value of message mapping, a structured technique for crafting coherent narratives grounded in robust scientific evidence. The course also highlighted the critical role of media relationships in effective science communication. Scientists attending the course were encouraged to identify and utilize appropriate media channels suited to specific messages. They also gained a better understanding of the importance of proactively organizing field visits, media briefings, and events to support accurate reporting of scientific advances, and of consistently sharing timely and reliable information to media representatives.
Ghana hosts 2nd Global Congress on new, emerging genetic biocontrol technologies
34634Ama Kudom-Agyemang, EnviroNews Nigeria, 2025-03-13 14:22:11.
From Monday, March 17 to Thursday, March 20, 2025, Ghana is hosting a gathering of science, health and communication experts to deliberate on and contribute to innovative scientific exploits for Africa’s health sector. The over 150 African national and international professionals from scientific institutions, academia, pharmaceuticals, biotechnology researchers, development and clinical organisations as well as science communicators would be brainstorming on new and emerging genetic biocontrol technologies that can tackle vector-borne diseases such as malaria, by sharing experiences and lessons across diverse disciplines related to genetic biocontrol technologies. The four-day gathering is the 2nd Global Congress in Africa on new and emerging genetic biocontrol technologies. The 1st Global Congress was held in Nairobi, Kenya in August, 2023. Ghana’s National Biosafety Authority (NBA) and the African Genetic Biocontrol Consortium (The Consortium) are jointly organising this 2nd Congress on the theme: “Harnessing genetic biocontrol potential solutions in a changing climate.”
CRISPR/Cas9 Genome Editing in the Diamondback Moth: Current Progress, Challenges, and Prospects
34556Asad, M., Chang, Y., Liao, J., & Yang, G., International Journal of Molecular Sciences, 26:1515. 2025-03-04 11:34:07.
The development of site-specific genome-editing tools like CRISPR (clustered regularly interspaced short palindromic repeat) and its associated protein, Cas9, is revolutionizing genetic engineering with its highly efficient mechanism, offering the potential for effective pest management. Recently, CRISPR/Cas9 gene-editing has been extensively utilized in the management of the diamondback moth, Plutella xylostella (L.), a highly destructive pest of vegetable crops, for different purposes, such as gene function analysis and genetic control. However, the progress related to this gene-editing tool in P. xylostella has not yet been summarized. This review highlights the progress and applications of CRISPR/Cas9 in uncovering the genes critical for development, reproduction, and insecticide resistance in P. xylostella. Moreover, the progress related to the CRISPR/Cas9 gene drive for population suppression and modifications has also been discussed. In addition to the significant progress made, challenges such as low germline editing efficiency and limited homology-directed repair remain obstacles to its widespread application. To address these limitations, we have discussed the different strategies that are anticipated to improve the efficiency of CRISPR/Cas9, paving the way to it becoming a pivotal tool in sustainable pest management. Therefore, the present review will help researchers in the future enhance the efficiency of the CRISPR/Cas9 system and use it to manage the diamondback moth.
Public attitudes to genetic technology for invasive pest control and preferences for engagement and information: a segmentation analysis
34499Hobman E.V., Mankad A., Carter, L., Collins K., Frontiers in Bioengineering and Biotechnology, 12. 2025-02-04 19:37:26.
Advances in genetic technology hold promise in managing the increasing problem of invasive pests. The current study sought to improve our understanding of public perceptions, and potential public engagement pathways and information needs as the technology is researched and potentially developed for deployment. A survey of 1,149 Australians was conducted, and the sample was segmented into 4 groups based on their attitudes: Certain Objectors, Fence Sitters, Cautious Supporters, and Certain Supporters. ‘Light touch’ engagement activities appeared to satisfy most people; yet more intensive engagements could be appropriate for a small group who hold negative views towards the technology. Across the board, people wanted to know about the potential risks, and the regulation and controls surrounding the gene editing technology. Those who held more positive views also showed an interest in the scientific processes and techniques, while people who held more negative views wanted to know what was being done to deal with social and ethical issues. The results provide insight into 1) the diversity of views, and associated beliefs and feelings, among the public when confronted with a synthetic biology solution to an environmental problem, 2) how public engagement activities can be tailored to align with people’s engagement beliefs and stated preferences, and 3) what issues biotechnology developers should address as they endeavour to design genetic technology in a socially responsible way.
Female mosquito targeted with venom to curb disease
34263Dann Okoth, Scidev.net, 2025-01-14 10:10:57.
A genetic biocontrol method which reduces the lifespan of female insects could work as fast as pesticides to reduce populations of disease-spreading mosquitoes and destructive crop pests, according to researchers. Insect pests pose a huge threat to global health and agriculture, causing hundreds of thousands of deaths, millions of infections, and costing billions in healthcare and crop damage each year. Biocontrol is increasingly seen as a viable alternative to pesticides, which can harm non-target species and ecosystems and are losing efficacy as resistance to them grows. A new approach called Toxic Male Technique (TMT), developed by researchers at the ARC Centre of Excellence in Synthetic Biology at Macquarie University, Australia, involves genetically engineering male insects to reduce the lifespan of the females they mate with. Researchers say it can be used to respond rapidly to outbreaks of agricultural pests as well as to fight mosquito-borne diseases such as malaria, dengue and Zika. “We hold that our technology has the potential of working as fast as pesticides without the attendant risks of harming other species and the environment,” says Samuel Beach a researcher in applied biosciences at Macquarie University and lead author of the study, published today in Nature Communications. According to Beach, the approach is more efficient than existing methods such as the Sterile Insect Technique or the release of insects carrying lethal genes, which work by releasing masses of sterilized or genetically modified males to mate with wild females.
Genetically Engineered Male Insects Shorten Their Mates’ Lifespans
34253Sneha Khedkar, The Scientist, 2025-01-13 15:13:56.
On a still night, as the air is thick with silence, the sharp, whining buzz of a mosquito shatters the calm. These blood-sucking insects that disturb people’s deep slumber are also responsible for spreading diseases such as dengue, chikungunya, malaria and Zika fever, which affect millions of people each year worldwide. Given the harmful effects of pesticides on the environment, combined with the emergence of mosquitoes resistant to pesticides, scientists are looking for alternative environment-friendly approaches for pest management. Now, researchers have developed a new population control method where male insects carrying toxic proteins can poison disease-spreading females during mating. The results, published in Nature Communications, describe a genetic biocontrol method that offers a fast and effective solution to managing pests. Such approaches are not entirely new. In the 1950s, when researchers mated female insects with radiologically sterilized males, they did not produce offsprings, reducing the next generation’s population. More recently, scientists propagated transgenes in insects that lower the fitness of future generations, resulting in decreased insect population. Although such methods are promising, they require at least one generation to take effect: Female insects may not produce offsprings, but they can continue transmitting infections. “As we’ve learned from COVID-19, reducing the spread of these diseases as quickly as possible is important to prevent epidemics,” said study author Samuel Beach, a graduate student in biologist Maciej Maselko’s lab at Macquarie University, in a press release.
A Y chromosome-linked genome editor for efficient population suppression in the malaria vector Anopheles gambiae
34215Tolosana, I., Willis, K., Gribble, M. et al., Nature Communications, 16:206. 2025-01-07 09:21:41.
Genetic control – the deliberate introduction of genetic traits to control a pest or vector population – offers a powerful tool to augment conventional mosquito control tools that have been successful in reducing malaria burden but that are compromised by a range of operational challenges. Self-sustaining genetic control strategies have shown great potential in laboratory settings, but hesitancy due to their invasive and persistent nature may delay their implementation. Here, instead, we describe a self-limiting strategy, designed to have geographically and temporally restricted effect, based on a Y chromosome-linked genome editor (YLE). The YLE comprises a CRISPR-Cas9 construct that is always inherited by males yet generates an autosomal dominant mutation that is transmitted to over 90% of the offspring and results in female-specific sterility. To our knowledge, our system represents a pioneering approach in the engineering of the Y chromosome to generate a genetic control strain for mosquitoes. Mathematical modelling shows that this YLE technology is up to seven times more efficient for population suppression than optimal versions of other self-limiting strategies, such as the widely used Sterile Insect Technique or the Release of Insects carrying a Dominant Lethal gene.
Public attitudes to genetic technology for invasive pest control and preferences for engagement and information: A segmentation analysis
34055Elizabeth Virginia Hobman, Aditi Mankad, Lucy Carter, Kerry Collins, Frontiers in Bioengineering and Biotechnology, 12. 2024-12-16 14:49:47.
This research focusses on understanding (1) how people perceive genetic technology to control invasive animal pests (feral pigs, cats etc.), and (2) how people would like to be engaged on, and/or informed about, decisions regarding the development of this genetic technology. The results have direct relevance to biotechnology developers as they seek to better understand public likely response to genetic technology. Results revealed the presence of distinct segments where people varied systematically in their attitudes towards the technology, and their engagement beliefs and preferences, and information needs. The results provide practical direction on (1) how to design public engagement activities and science communications that accord with people's preferences, and (2) the issues that biotechnology developers should address as they endeavour to create socially responsible genetic technologies.
How genetically engineered mice could stop the spread of Lyme disease
33874Cristela Guerra and Stephanie Brown, WBUR Radio Boston, 2024-12-10 16:36:59.
New England has some of the highest rates of Lyme disease in the country. MIT researchers are trying to fight the disease in a project that involves releasing hundreds of thousands of engineered mice onto the shores of Nantucket and Martha's Vineyard. On Radio Boston, Kevin Esvelt, an associate professor at the MIT Media Lab and the inventor of CRISPR-based gene drive, discusses the project.
Biotechnology-enhanced genetic controls of the global pest Drosophila suzukii
33392Ying Yan, Hassan M.M. Ahmed, Ernst A. Wimmer, et al., Trends in Biotechnology, 2024-11-04 17:35:39.
Genetic control is a biological control method that introduces traits that sterilize, kill, or modify the population via intraspecific mating. Therefore, it is regarded as a species-specific and environmentally friendly management option for pest species. Spotted wing Drosophila (SWD) is an ideal insect model for studying genetic control strategies due to its pest status, laboratory-friendly biology, and close relationship to Drosophila melanogaster, which has abundant genetic resources. Different biotechnology-enhanced genetic control strategies of SWD are featured. The working schematics, control efficacies, some resistance mechanisms, and possible future development of these strategies are described. The designs and experience from these studies aid in the sustainable control of SWD and serve as essential references to other insect pests of economic or public health importance.
Communicating the uncertainties associated with genetic biocontrol approaches: insights from communicators, science journalists and scientists in Africa
32538Tonui, W. K., Ogoyi, D., Thuo, C., Tareh, C., et al., Journal of Science Communication, 23. 2024-09-25 12:13:55.
Genetic biocontrol approaches, such as gene drive technology is rapidly gaining interest from scientists and public health professionals due to their potential to overcome many challenges of current malaria control tools and strategies. This is particularly the case in Africa where the burden of malaria is most significant. Uncertainty exists about whether these approaches will work, how effective they might be, who is controlling them, and potential unintended consequences for human health and the environment. Therefore, efforts to enhance the understanding of genetic engineering and biotechnology are needed, to ensure that accurate information about this technology is disseminated in the media by science communicators including the journalists and scientists. In this practice insight, we review the outcomes from workshops and courses hosted by the African Genetic Biocontrol Consortium aimed at equipping communicators and journalists with skilful techniques to proficiently articulate the uncertainties associated with genetic biocontrol interventions to the African public. we discuss the gaps and provide insight on how communicators can address some of the basic challenges of developing effective communication and decision-making for genetic biocontrol approaches in Africa.
Scientists want to use mosquito stomach bacteria to end malaria
31201Chia-Yu Chen & Shüné Oliver, Alliance for Science, 2024-08-27 14:05:18.
The months of September to May are an unfortunate season in South Africa: malaria season. The mosquito-borne disease is found in the north-eastern districts of KwaZulu-Natal, Mpumalanga and Limpopo provinces. There are fewer malaria cases in South Africa compared to other African countries. The World Health Organization estimated there were over 10 million cases of malaria in Mozambique in 2022. South Africa, that country’s neighbor, recorded 5,183 malaria cases between September 2022 and August 2023. Its relatively low case numbers may be a result of South African health authorities’ excellent work in controlling the disease (control efforts began more than 120 years ago). The last major malaria outbreak in South Africa was in 2000, when more than 60,000 cases were recorded. Also notable was the 2017 outbreak, with 28,264 cases. This combination of control efforts and low numbers may mean that South Africans think malaria is not something they need to worry about unless they travel to provincial hotspots in the months of September to May. But it remains a disease of concern – not just within the country’s borders, but in the broader southern African region. Many researchers like ourselves are working towards eliminating or even, one day, totally eradicating the disease. “Elimination” doesn’t mean there will be no malaria in the region at all. Instead, it would mean that local mosquitoes no longer spread the disease in South Africa. The reason that South Africa has not fully eliminated malaria is precisely because its local mosquito populations are still transmitting the disease. In fact, in 2023, about 17 percent of people who got sick from malaria had caught it in South Africa and not from travelling to neighboring African countries. Scientists are using and developing many different “weapons” in the fight against malaria. Our approach involves using mosquitoes’ own gut bacteria to prevent them from spreading malaria. This is a form of biocontrol, which involves the use of living organisms or natural substances to control harmful pests. The groundwork we’re laying with this ongoing research will, we believe, allow us and other scientists to create a powerful malaria-beating tool.
How to Use Genetic Biocontrol to Manage Insect Pests
29891Scientific Animations Without Borders, YouTube, 2024-05-07 16:41:35.
Pest insects often transmit disease to humans and animals and destroy crops. Controlling these pests can improve human health and increase agricultural production. Pest insects are often controlled by releasing other insects into the environment that will specifically kill the pests. This method of pest control is called biological control and is environmentally friendly because it reduces reliance on chemical insecticides and targets only the pest insects. Genetic biocontrol is a type of biological control where the released insects are the same species as the pest but with critical genetic differences and traits that affect their reproduction or lifespan.
Wolbachia Infection through Hybridization to Enhance an Incompatible Insect Technique-Based Suppression of Aedes albopictus in Eastern Spain
29086Cholvi M, Trelis M, Bueno-Marí R, Khoubbane M, Gil R, Marcilla A, Moretti R., Insects, 15. 2024-04-04 09:29:30.
Wolbachia bacteria occur naturally as symbionts of many insect species and are responsible for various phenomena that modify the hosts’ reproductive biology. Among them, cytoplasmic incompatibility (CI) refers to the sterility of eggs produced by crosses between infected males and females that are uninfected or infected by a non-compatible strain of these bacteria. CI can be exploited for vector control by establishing an opportune Wolbachia infection in a laboratory population of a target insect species and then releasing the infected males into the environment as sterilizing agents. In the present work, a suitable Wolbachia strain was introduced into a Spanish population of the Asian tiger mosquito, Aedes albopictus, through hybridization with the laboratory line, ARwP, already tested as an efficient control tool against this vector. The obtained hybrids were compared with the ARwP to ascertain the effects derived from transferring the infection to a different Ae. albopictus population. No significant differences between lines were found regarding survival, female fecundity, and egg fertility. Importantly, the eggs produced by crosses between males of the hybrid lines and unmodified wild females were 99.9% sterile. This result encourages further studies to explore the feasibility of a Wolbachia-based control program against the Asian tiger mosquito in Spain.
Genome editing in pests: basic science to applications
28908Chen, X., Palli, S.R., Journal of Pest Science, 2024-02-20 15:39:21.
Recent developments in sequencing technologies produced enormous data on gene sequences and the identity of genes in many pest insects and disease vectors. However, the function of many of these genes is unknown. Functional genomics studies to uncover gene function in pest insects are urgently needed. RNA interference methods could be used in some insects but not most due to their variable efficiency among insect pests. Recently developed clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system of genome editing method is being developed for use in many insect pests. This technology has already been demonstrated to function in more than 40 insect pest species from seven orders and has contributed to advances in pest biology and the development of improved pest management methods. This review summarizes recent results of CRISPR/Cas9 technology developments and their contributions to advancing the basic and applied science of insect pests and disease vectors.
Recombinant venom proteins in insect seminal fluid reduces female lifespan
28821Samuel J. Beach, Maciej Maselko, bioRxiv, 2024-01-23 14:49:23.
The emergence of insecticide resistance has increased the need for alternative pest management tools1,2 Numerous genetic biocontrol approaches, which involve the release of genetically modified organisms to control pest populations, are in various stages of development to provide highly targeted pest control3-7. However, all current mating-based genetic biocontrol technologies function by releasing engineered males which skew sex-ratios or reduce offspring viability in subsequent generations. This allows mated females continue to cause harm (e.g. transmit disease). Here, we demonstrate the first example of intragenerational genetic biocontrol, wherein mating with engineered males reduces female lifespan. The toxic male technique (TMT) involves the heterologous expression of insecticidal proteins within the male reproductive tract that are transferred to females via mating. We demonstrate TMT in Drosophila melanogaster males, which reduce the median lifespan of mated females by 37 - 59% compared to controls mated to wild type males. Agent-based models of Aedes aegypti predict that compared to existing genetic biocontrol technologies, even modest levels of mated female mortality could allow TMT to suppress a female population substantially faster, which is likely to result in reduced disease burdens. TMT presents a novel approach for combatting outbreaks of disease vectors and agricultural pests.
To End Malaria In Africa, a Scientist From Africa Invented Gene Drive Technology.
28728Salman Ahmad, CTN News, 2023-12-19 12:41:22.
Abdoulaye Diabate, a scientist from Africa, is currently working on a groundbreaking technology called ‘gene drive’ that has the potential to eradicate malaria or the mosquitoes that cause it from the continent. Diabate, who received the prestigious 2023 Falling Walls Prize for Science and Innovation Management, is developing an ingenious technique that can eliminate female mosquitoes responsible for transmitting malaria by modifying their genes. Using gene drive technology, the reproduction of female mosquitoes is hindered by releasing genetically modified male mosquitoes into the environment. This approach would result in a significant reduction in the number of female mosquitoes, thereby combating malaria throughout the continent.
Upper Bound on the Mutational Burden Imposed by a CRISPR-Cas9 Gene-Drive Element
28722Michael S. Overton, Sean E. Guy, Xingsen Chen, Alena Martsul, Krypton Carolino, Omar S. Akbari, Justin R. Meyer, Sergey Kryazhimskiy, bioRxiv, 2023-12-19 12:04:20.
CRISPR-Cas9 gene drives (CCGDs) are powerful tools for genetic control of wild populations, useful for eradication of disease vectors, conservation of endangered species and other applications. However, Cas9 alone and in a complex with gRNA can cause double-stranded DNA breaks at off-target sites, which could increase the mutational load and lead to loss of heterozygosity (LOH). These undesired effects raise potential concerns about the long-term evolutionary safety of CCGDs, but the magnitude of these effects is unknown. To estimate how the presence of a CCGD or a Cas9 alone in the genome affects the rates of LOH events and de novo mutations, we carried out a mutation accumulation experiment in yeast Saccharomyces cerevisiae. Despite its substantial statistical power, our experiment revealed no detectable effect of CCGD or Cas9 alone on the genome-wide rates of mutations or LOH events, suggesting that these rates are affected by less than 30%. Nevertheless, we found that Cas9 caused a slight but significant shift towards more interstitial and fewer terminal LOH events, and the CCGD caused a significant difference in the distribution of LOH events on Chromosome V. Taken together, our results show that these genetic elements impose a weak and likely localized additional mutational burden in the yeast model. Although the mutagenic effects of CCGDs need to be further evaluated in other systems, our results suggest that the effect of CCGDs on off-target mutation rates and genetic diversity may be acceptable.
Manipulating the Destiny of Wild Populations Using CRISPR
28626Raban R, Marshall JM, Hay BA, Akbari OS., Annual Reviews, 57:361-390. 2023-12-04 09:57:57.
Genetic biocontrol aims to suppress or modify populations of species to protect public health, agriculture, and biodiversity. Advancements in genome engineering technologies have fueled a surge in research in this field, with one gene editing technology, CRISPR, leading the charge. This review focuses on the current state of CRISPR technologies for genetic biocontrol of pests and highlights the progress and ongoing challenges of using these approaches.
Advances and challenges in synthetic biology for mosquito control
28545Shih-Che Weng, Reem A. Masri, Omar S. Akbari, Trends in Parasitology, 2023-11-28 11:40:23.
Mosquito-borne illnesses represent a significant global health peril, resulting in approximately one million fatalities annually. West Nile, dengue, Zika, and malaria are continuously expanding their global reach, driven by factors that escalate mosquito populations and pathogen transmission. Innovative control measures are imperative to combat these catastrophic ailments. Conventional approaches, such as eliminating breeding sites and using insecticides, have been helpful, but they face challenges such as insecticide resistance and environmental harm. Given the mounting severity of mosquito-borne diseases, there is promise in exploring innovative approaches using synthetic biology to bolster mosquitoes' resistance to pathogens, or even eliminate the mosquito vectors, as a means of control. This review outlines current strategies, future goals, and the importance of gene editing for global health defenses against mosquito-borne diseases.
Oxitec concludes GMO mosquito release phase
28361Anonymous, keysnews.com, 2023-11-08 09:35:19.
Oxitec and the Florida Keys Mosquito Control District announced last week that the release phase during the third season of the FKMCD-Oxitec Mosquito Project has concluded for the 2023 season. Mosquito population monitoring will continue for the next several weeks.9
Current Status of the Main Olive Pests: Useful Integrated Pest Management Strategies and Genetic Tools
28380E. Lantero, B. Matallanas and C. Callejas, Applied Sciences, 13. 2023-11-06 09:55:38.
Mediterranean olive cultivation faces challenges in the global environmental change context. Pests and diseases caused by arthropods such as Bactrocera oleae, Prays oleae, and certain vectors of Xylella fastidiosa are expected to increase and spread in part due to this global scenario. The control of these arthropods has relied on synthetic pesticides, the misuse of which has led to pest population resistance and concerns about their negative impacts on biodiversity and global health. Integrated pest management (IPM) methods have emerged through the careful consideration of all available control techniques and the subsequent integration of appropriate measures that discourage the development of pest populations. This paper reviews the IPM guidelines for olive cultivation, prioritizing the use of biological control methods, and the integration of genetics and biotechnology, which bring precision, efficacy, and safety. It evidences the importance of genetic analysis in pest populations, pesticide resistance and in the contributions of predators to pest control. Advances in formulations and delivery systems for pesticides such as Bacillus thuringiensis, plant-incorporated protectants, improved SIT techniques, and the specific efficacy of biologicals pesticides are covered. Finally, this paper explores promising tools such as RNAi and gene drive while recognizing the ethical, environmental, and regulatory challenges associated with their use. Shortly, these innovations have the potential to reduce the environmental impacts of pests while ensuring the long-term viability of the olive industry.
Biotechnological Potential of Microorganisms for Mosquito Population Control and Reduction in Vector Competence
28272R. D. Katak, A. M. Cintra, B. C. Burini, O. Marinotti, J. A. Souza-Neto and E. M. Rocha, Insects, 14. 2023-10-30 07:59:35.
Mosquitoes transmit pathogens that cause human diseases such as malaria, dengue fever, chikungunya, yellow fever, Zika fever, and filariasis. Biotechnological approaches using microorganisms have a significant potential to control mosquito populations and reduce their vector competence, making them alternatives to synthetic insecticides. Ongoing research has identified many microorganisms that can be used effectively to control mosquito populations and disease transmission. However, the successful implementation of these newly proposed approaches requires a thorough understanding of the multipronged microorganism-mosquito-;pathogen-environment interactions. Although much has been achieved in discovering new entomopathogenic microorganisms, antipathogen compounds, and their mechanisms of action, only a few have been turned into viable products for mosquito control. There is a discrepancy between the number of microorganisms with the potential for the development of new insecticides and/or antipathogen products and the actual available products, highlighting the need for investments in the intersection of basic research and biotechnology.
Could a new gene-editing technique be a major breakthrough in the battle against malaria?
27888B. Cottam, GEOGRAPHICAL, 2023-09-23 07:58:35.
The idea is that since female mosquitoes typically only mate once, the mass release of the sterile male mosquitoes should prevent wild females from producing future generations. Insect populations can and have already been successfully suppressed by the release of sterilised males that have been irradiated with gamma or x-rays, a technique that was originally trialled in the USA as a way to control agricultural pests such as fruit flies and screwworms. However, that method of sterilisation has a detrimental impact on the fitness of male mosquitoes, which then struggle to compete for mates with the wild males. That’s why sterilisation needs to be done genetically.
Quantifying Fitness Costs in Transgenic Aedes aegypti Mosquitoes
27981I. Sanchez-Vargas, A. E. Williams, L. E. Martin, I. Martin-Martin, S. Bennett, K. E. Olson and E. Calvo, Journal of Visualized Experiments, 2023-09-15 07:51:42.
Transgenic mosquitoes often display fitness costs compared to their wild-type counterparts. In this regard, fitness cost studies involve collecting life parameter data from genetically modified mosquitoes and comparing them to mosquitoes lacking transgenes from the same genetic background. This manuscript illustrates how to measure common life history traits in the mosquito Aedes aegypti, including fecundity, wing size and shape, fertility, sex ratio, viability, development times, male contribution, and adult longevity. These parameters were chosen because they reflect reproductive success, are simple to measure, and are commonly reported in the literature. The representative results quantify fitness costs associated with either a gene knock-out or a single insertion of a gene drive element. Standardizing how life parameter data are collected is important because such data may be used to compare the health of transgenic mosquitoes generated across studies or to model the transgene fixation rate in a simulated wild-type mosquito population. Although this protocol is specific for transgenic Aedes aegypti, the protocol may also be used for other mosquito species or other experimental treatment conditions, with the caveat that certain biological contexts may require special adaptations.
Buzzing breakthrough: genetic engineering gives mosquito control an upgrade
27841Sivasubbu, Sridhar Scaria, Vinod, The Hindu, 2023-09-10 09:28:26.
Throughout human history, mosquitoes have constantly buzzed in the background of human existence, irritating us with their incessant bites and occasionally wreaking havoc by transmitting deadly diseases. The earliest known mosquitoes from the fossil record date back at least 70 million years, and evidence of mosquito-borne diseases like malaria dates back to Egyptian mummies from 2000 BC. Apart from malaria, which claims the lives of over half a million people every year and infects close to 250 million, mosquitoes serve as vectors for various other diseases. These include dengue, Zika, lymphatic filariasis, and yellow fever. Understandably, our relationship with these tiny, blood-sucking insects has been far from cordial.
Transgenic approaches in medical entomology: 2022 highlights
27751M. L. Simões, Journal of Medical Entomology, tjad105. 2023-09-02 07:40:51.
Transgenesis has emerged as a powerful tool to control arthropod vectors and the diseases they transmit. Here, we highlight the latest developments on transgenic approaches in ticks, Anopheles and Aedes mosquitoes, based on recent findings and significant papers from 2022. We survey topics ranging from population replacement, population suppression, gene drive, sex ratio distortion, public engagement and capacity building, and gene editing in ticks. While presenting these advancements, we discuss the current challenges surrounding the application of arthropod transgenesis for the development of novel vector control strategies.
The impact of predators of mosquito larvae on Wolbachia spreading dynamics
27651Z. Zhu, Y. Hui and L. Hu, Journal of Biological Dynamics, 17:2249024. 2023-08-21 07:05:13.
Dengue fever creates more than 390 million cases worldwide yearly. The most effective way to deal with this mosquito-borne disease is to control the vectors. In this work we consider two weapons, the endosymbiotic bacteria Wolbachia and predators of mosquito larvae, for combating the disease. As Wolbachia-infected mosquitoes are less able to transmit dengue virus, releasing infected mosquitoes to invade wild mosquito populations helps to reduce dengue transmission. Besides this measure, the introduction of predators of mosquito larvae can control mosquito population. To evaluate the impact of the predators on Wolbachia spreading dynamics, we develop a stage-structured five-dimensional model, which links the predator-prey dynamics with the Wolbachia spreading. By comparatively analysing the dynamics of the models without and with predators, we observe that the introduction of the predators augments the number of coexistence equilibria and impedes Wolbachia spreading. Some numerical simulations are presented to support and expand our theoretical results.
Delftia tsuruhatensis TC1 symbiont suppresses malaria transmission by anopheline mosquitoes
27565W. Huang, J. Rodrigues, E. Bilgo, J. R. Tormo, J. D. Challenger, C. De Cozar-Gallardo, I. Pérez-Victoria, F. Reyes, P. Castañeda-Casado, E. J. Gnambani, D. F. d. S. Hien, M. Konkobo, B. Urones, I. Coppens, A. Mendoza-Losana, L. Ballell, A. Diabate, T. S., Science, 381:533-540. 2023-08-04 07:30:48.
Malaria control demands the development of a wide range of complementary strategies. We describe the properties of a naturally occurring, non?genetically modified symbiotic bacterium, Delftia tsuruhatensis TC1, which was isolated from mosquitoes incapable of sustaining the development of Plasmodium falciparum parasites. D. tsuruhatensis TC1 inhibits early stages of Plasmodium development and subsequent transmission by the Anopheles mosquito through secretion of a small-molecule inhibitor. We have identified this inhibitor to be the hydrophobic molecule harmane. We also found that, on mosquito contact, harmane penetrates the cuticle, inhibiting Plasmodium development. D. tsuruhatensis TC1 stably populates the mosquito gut, does not impose a fitness cost on the mosquito, and inhibits Plasmodium development for the mosquito?s life. Contained field studies in Burkina Faso and modeling showed that D. tsuruhatensis TC1 has the potential to complement mosquito-targeted malaria transmission control. Malaria mosquitoes can act as hosts to several microorganisms, including commensal bacterial species. Huang et al. noticed that some laboratory colonies of anopheline mosquitoes were incapable of transmitting malaria parasites. These insects also harbored a few cells of a bacterium called Delftia tsuruhatensis TC1, which produces a toxic alkaloid called harmane. Bacteria-produced harmane inhibited the development of female Plasmodium parasite gametes in the mosquito gut. Harmane was found to be a contact poison that could also cross the mosquito cuticle to kill developing malaria parasites. Contained field trials in Burkina Faso, coupled with modeling studies, showed that the bacterium has the potential to be deployed in mosquito breeding sites as a component of malaria control. ?Caroline Ash A naturally occurring bacterium of anopheline mosquitoes produces an alkaloid that arrests the development of co-occurring Plasmodium oocytes
Microbe stops mosquitoes from harboring malaria parasite
27567C. Offord, Science, 2023-08-03 07:31:08.
Researchers have tried to use microbes to control mosquito-borne diseases before. The virus-fighting bacterium Wolbachia pipientis has shown particular promise against dengue fever in recent clinical trials and is already used in some areas of the world. But most methods for blocking malaria-causing Plasmodium parasites, which are transmitted by different mosquito species from dengue, have relied on genetically modified bacteria. That’s a major obstacle to regulatory and public acceptance, Barillas-Mury notes, given the unknowns of releasing edited organisms into the wild. The latest news, commentary, and research, free to your inbox daily The bacterium in the new study, published today in Science, inhibits the malaria parasite without any genetic tinkering by humans. Janneth Rodrigues, a scientific lead in global health medicines R&D at GlaxoSmithKline, and colleagues stumbled across the microbe at a GSK research center in Spain, after noticing the mosquitoes they were using for malaria research were getting harder to infect with Plasmodium.
Cost-effectiveness of Precision Guided SIT for Control of Anopheles gambiae in the Upper River Region, The Gambia
27060G. William, R. Robyn, M. Agastya, M. S. C. Hector, S. Andrea, Z. David, G. I. Patrick, D. Umberto, Alessandro, M. M. John and A. Omar, bioRxiv, 2023.07.20.549762. 2023-07-22 06:41:45.
Precision-guided sterile insect technique (pgSIT) is an extremely promising vector control intervention that can reduce and potentially eliminate the unacceptable malaria burden, particularly in sub-Saharan Africa. Here we explore the cost effectiveness of using this approach in Africa using mathematical modeling and economical analysis. Overall, we find that pgSIT represents a cost-effective and promising approach to A. gambiae control in The Gambia, with the potential to deliver significant economic and social benefits.Competing Interest StatementThis work was supported by funding from an Open Philanthropy award (309937-0001). The views, opinions, and/or findings expressed are those of the authors and should not be interpreted as representing the official views or policies of the U.S. government. Figures were created using www.BioRender.com.
Engineered Gut Symbiotic Bacterium-Mediated RNAi for Effective Control of Anopheles Mosquito Larvae
27559J. J. Ding, C. L. Cui, G. D. Wang, G. Wei, L. Bai, Y. F. Li, P. L. Sun, L. Dong, Z. C. Liu, J. Q. Yun, F. Li, K. Li, L. He and S. B. Wang, Microbiology Spectrum, 2023-07-17 06:46:02.
Anopheles mosquitoes are the primary vectors for the transmission of malaria parasites, which poses a devastating burden on global public health and welfare. The recent invasion of Anopheles stephensi in Africa has made malaria eradication more challenging due to its outdoor biting behavior and widespread resistance to insecticides. To address this issue, we developed a new approach for mosquito larvae control using gut microbiota-mediated RNA interference (RNAi). We engineered a mosquito symbiotic gut bacterium, Serratia fonticola, by deleting its RNase III gene to produce double-stranded RNAs (dsRNAs) in the mosquito larval gut. We found that the engineered S. fonticola strains can stably colonize mosquito larval guts and produce dsRNAs dsMet or dsEcR to activate RNAi and effectively suppress the expression of methoprene-tolerant gene Met and ecdysone receptor gene EcR, which encode receptors for juvenile hormone and ecdysone pathways in mosquitoes, respectively. Importantly, the engineered S. fonticola strains markedly inhibit the development of A. stephensi larvae and leads to a high mortality, providing an effective dsRNA delivery system for silencing genes in insects and a novel RNAi-mediated pest control strategy. Collectively, our symbiont-mediated RNAi (smRNAi) approach offers an innovative and sustainable method for controlling mosquito larvae and provides a promising strategy for combating malaria.IMPORTANCE Mosquitoes are vectors for various diseases, imposing a significant threat to public health globally. The recent invasion of A. stephensi in Africa has made malaria eradication more challenging due to its outdoor biting behavior and widespread resistance to insecticides. RNA interference (RNAi) is a promising approach that uses dsRNA to silence specific genes in pests. This study presents the use of a gut symbiotic bacterium, Serratia fonticola, as an efficient delivery system of dsRNA for RNAi-mediated pest control. The knockout of RNase III, a dsRNA-specific endonuclease gene, in S. fonticola using CRISPR-Cas9 led to efficient dsRNA production. Engineered strains of S. fonticola can colonize the mosquito larval gut and effectively suppress the expression of two critical genes, Met and EcR, which inhibit mosquito development and cause high mortality in mosquito larvae. This study highlights the potential of exploring the mosquito microbiota as a source of dsRNA for RNAi-based pest control. Mosquitoes are vectors for various diseases, imposing a significant threat to public health globally. The recent invasion of A. stephensi in Africa has made malaria eradication more challenging due to its outdoor biting behavior and widespread resistance to insecticides.
CRISPR’d Mosquitoes With All-Male Offspring Could Help Eradicate Malaria
26610V. B. Ramirez, Singuarity Hub, 2023-07-13 13:17:26.
Though at least one vaccine for malaria is in use, it remains one of the deadliest diseases in the world. Almost half of the world’s population lives in areas where malaria transmission occurs, and an estimated 619,000 people died of the disease in 2021. Worse yet, the vast majority of cases leading to death are in young children. Researchers from the University of California in San Diego may have found a way to reduce this burden of disease. They used the gene editing tool CRISPR to alter a gene that controls sexual development in mosquitoes. Male mosquitoes don’t bite humans; it’s the females that spread malaria and other diseases. The UCSD team’s method uses gene editing to kill all female mosquito offspring within a given population of the insects. The mosquito species in question is Anopheles gambiae, commonly called the African malaria mosquito and described as “the most efficient vector of human malaria.” They’re anthropophilic, meaning they like human blood more than animal blood, and they thrive in hot climates with a lot of moisture. Why such an insect exists in the first place is hard to comprehend, is it not?
Fighting the battle against evolution: designing genetically modified organisms for evolutionary stability
28008M. Arbel-Groissman, I. Menuhin-Gruman, D. Naki, S. Bergman and T. Tuller, Trends in Biotechnology, 2023-07-12 06:48:15.
Synthetic biology has made significant progress in many areas, but a major challenge that has received limited attention is the evolutionary stability of synthetic constructs made of heterologous genes. The expression of these constructs in microorganisms, that is, production of proteins that are not necessary for the organism, is a metabolic burden, leading to a decrease in relative fitness and make the synthetic constructs unstable over time. This is a significant concern for the synthetic biology community, particularly when it comes to bringing this technology out of the laboratory. In this review, we discuss the issue of evolutionary stability in synthetic biology and review the available tools to address this challenge
Genome and Transcriptome Analyses Facilitate Genetic Control of Wohlfahrtia magnifica, a Myiasis-Causing Flesh Fly
27427Z. Jia, S. Hasi, D. Zhan, B. Hou, C. Vogl and P. A. Burger, Insects, 14. 2023-07-10 08:53:12.
Myiasis caused by Wohlfahrtia magnifica is a widespread parasitic infestation in mammals. The infested host suffers from damage as the developing larvae feed on its tissues. For the control of myiasis infestation, genetic methods have been shown to be effective and promising as an alternative to insecticides. Combining genome, isoform sequencing (Iso-Seq), and RNA sequencing (RNA-seq) data, we isolated and characterized two sex-determination genes, W. magnifica transformer (Wmtra) and W. magnifica transformer2 (Wmtra2), whose orthologs in a number of insect pests have been utilized to develop genetic control approaches. Wmtra transcripts are sex-specifically spliced; only the female transcript encodes a full-length functional protein, while the male transcript encodes a truncated and non-functional polypeptide due to the presence of the male-specific exon containing multiple in-frame stop codons. The existence of five predicted TRA/TRA2 binding sites in the male-specific exon and the surrounding intron of Wmtra, as well as the presence of an RNA-recognition motif in WmTRA2 may suggest the auto-regulation of Wmtra by its own protein interacting with WmTRA2. This results in the skipping of the male-specific exon and translation of the full-length functional protein only in females. Our comparative study in dipteran species showed that both the WmTRA and WmTRA2 proteins exhibit a high degree of similarity to their orthologs in the myiasis-causing blow flies. Additionally, transcriptome profiling performed between adult females and adult males reported 657 upregulated and 365 downregulated genes. Functional analysis showed that among upregulated genes those related to meiosis and mitosis Gene Ontology (GO) terms were enriched, while, among downregulated genes, those related to muscle cell development and aerobic metabolic processes were enriched. Among the female-biased gene set, we detected five candidate genes, vasa (vas), nanos (nanos), bicoid (bcd), Bicaudal C (BicC), and innexin5 (inx5). The promoters of these genes may be able to upregulate Cas9 expression in the germline in Cas9-based homing gene drive systems as established in some flies and mosquitoes. The isolation and characterization of these genes is an important step toward the development of genetic control programs against W. magnifica infestation.
New Genetic Technology Developed to Halt Malaria-Spreading Mosquitoes
26473M. Aguilera, UC San Diego Today, 2023-07-05 08:09:31.
Fortunately, scientists are developing safe technologies to stop the transmission of malaria by genetically editing mosquitoes that spread the parasite that causes the disease. Researchers at the University of California San Diego led by Professor Omar Akbari’s laboratory have engineered a new way to genetically suppress populations of Anopheles gambiae, the mosquitoes that primarily spread malaria in Africa and contribute to economic poverty in affected regions. The new system targets and kills females of the A. gambiae population since they bite and spread the disease. Publishing July 5 in the journal Science Advances, first-author Andrea Smidler, a postdoctoral scholar in the UC San Diego School of Biological Sciences, along with former master’s students and co-first authors James Pai and Reema Apte, created a system called Ifegenia, an acronym for “inherited female elimination by genetically encoded nucleases to interrupt alleles.” The technique leverages the CRISPR technology to disrupt a gene known as femaleless (fle) that controls sexual development in A. gambiae mosquitoes.
Nuclear Technique Used in Europe for First time to Battle Yellow Fever Mosquito Found in Cyprus
26314IAEA, IAEA, 2023-06-27 07:43:22.
Cyprus this month released the first batch of 100,000 sterile mosquitos to begin the implementation of a Food and Agriculture Organization (FAO) and International Atomic Energy Agency (IAEA) project testing the use of a nuclear technique to eradicate an invasive species of mosquitoes found in the country.Cyprus confirmed the presence of the Aedes aegypti mosquito, also called Yellow Fever mosquito, on the island in 2022. This species of mosquito can carry serious vector-borne diseases such as chikungunya, dengue, yellow fever and Zika. The Aedes albopictus - also a carrier for such diseases - was also confirmed to be present on the island in 2022. Vector-borne diseases cause over 700,000 global deaths per year and the presence of the two species poses an immediate threat to Cyprus’ economy and healthcare system in case of a disease outbreak.
Molecular detection of reproductive symbionts and parthenogenesis experiments in Tuta absoluta from Argentina: facing potential for sustainable and specific pest control strategies
26184C. Cagnotti, C. Conte, J. Kramar, S. Lanzavecchia and S. López, Entomologia Experimentalis et Applicata, 2023-06-07 12:24:43.
Tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a key pest of tomato crops. Specific and environmentally friendly control strategies against this pest, such as the sterile insect technique (SIT), are under development and sexual reproduction has emerged as a key focal point to ensure its success. In the present study, we analyzed four representative T. absoluta populations from Argentina, focusing on the molecular detection of endosymbionts potentially associated with reproductive abnormalities and on determining whether parthenogenesis can occur under laboratory conditions. Larvae of T. absoluta were collected in commercial tomato plantations from La Plata and Mar del Plata (both in Buenos Aires province), Bella Vista (Corrientes province), and Yuto (Jujuy province). Tuta absoluta adults were evaluated by standard PCR for the presence of reproductive endosymbionts (Wolbachia sp., Spiroplasma sp., Arsenophonus sp., Cardinium sp., and Rickettsia sp.). For parthenogenesis assays, 20–23 virgin females from each T. absoluta geographic population were life-long isolated in Petri dishes with a tomato leaf. Fecundity, fertility, and female longevity were estimated and compared with results from mated females from each population. Our results showed the presence of a unique endosymbiont (Wolbachia sp. supergroup B, sequence type 41). Fecundity of the unmated females was significantly lower than fecundity of mated females in all T. absoluta populations. In addition, unmated females only laid infertile eggs. In conclusion, the absence of parthenogenesis in T. absoluta from representative geographic populations supports the implementation of SIT and mating disruption as effective control strategies against this pest in Argentina. © 2023 Netherlands Entomological Society.
A framework for identifying fertility gene targets for mammalian pest control
25416C. C. Anna, A. Alana, E. Rey, E. Kevin, K. Sebastian, D. Ludovic, C. Jackson, E. C. Samuel, W. M. Philipp and J. G. Neil, bioRxiv, 2023.05.30.542751. 2023-06-01 07:38:46.
Fertility-targeted gene drives have been proposed as an ethical genetic approach for managing wild populations of vertebrate pests for public health and conservation benefit. This manuscript introduces a framework to identify and evaluate target gene suitability based on biological gene function, gene expression, and results from mouse knockout models. This framework identified 16 genes essential for male fertility and 12 genes important for female fertility that may be feasible targets for mammalian gene drives and other non-drive genetic pest control technology. Further, a comparative genomics analysis demonstrates the conservation of the identified genes across several globally significant invasive mammals. In addition to providing important considerations for identifying candidate genes, our framework and the genes identified in this study may have utility in developing additional pest control tools such as wildlife contraceptives.Competing Interest StatementThe authors have declared no competing interest.
CRISPR-based gene editing of non-homologous end joining factors biases DNA repair pathway choice toward single-strand annealing in Aedes aegypti
25461K. Chae, J. M. Overcash, C. Dawson, C. Valentin, H. Tsujimoto, K. M. Myles and Z. N. Adelman, Current Research in Biotechnology, 5:100133. 2023-05-29 08:04:22.
To maintain genome stability, eukaryotic cells orchestrate DNA repair pathways to process DNA double-strand breaks (DSBs) that result from diverse developmental or environmental stimuli. Bias in the selection of DSB repair pathways, either non-homologous end joining (NHEJ) or homology-directed repair (HDR), is also critical for efficient gene editing and for homing-based gene drive approaches developed for the control of disease-transmitting vector mosquitoes. However, little is understood about DNA repair homeostasis in the mosquito genome. Here, we utilized CRISPR/Cas9 to generate indel mutant strains for core NHEJ factors ku80, DNA ligase IV (lig4), and DNA-PKcs in the mosquito Aedes aegypti and evaluated the corresponding effects on DNA repair. In a plasmid-based assay, disruption of ku80 or lig4, but not DNA-PKcs, reduced both NHEJ and SSA. However, a transgenic reporter strain-based test revealed that those mutations significantly biased DNA repair events toward SSA. Interestingly, ku80 mutation also significantly increased the end joining rate by a yet-characterized mechanism in males. Our study provides evidence that the core NHEJ factors have an antagonistic effect on SSA-based DSB repair of the Ae. aegypti genome. Down-modulating the NHEJ pathway can enhance the efficiency of nuclease-based genetic control approaches, as most of those operate by homology-based repair processes along with extensive DNA end resection that is antagonized by NHEJ.
Mosquito gene targeted RNAi studies for vector control
25650M. Yadav, N. Dahiya and N. Sehrawat, Functional and Integrative Genomics, 23:180. 2023-05-25 07:55:21.
Vector-borne diseases are serious public health concern. Mosquito is one of the major vectors responsible for the transmission of a number of diseases like malaria, Zika, chikungunya, dengue, West Nile fever, Japanese encephalitis, St. Louis encephalitis, and yellow fever. Various strategies have been used for mosquito control, but the breeding potential of mosquitoes is such tremendous that most of the strategies failed to control the mosquito population. In 2020, outbreaks of dengue, yellow fever, and Japanese encephalitis have occurred worldwide. Continuous insecticide use resulted in strong resistance and disturbed the ecosystem. RNA interference is one of the strategies opted for mosquito control. There are a number of mosquito genes whose inhibition affected mosquito survival and reproduction. Such kind of genes could be used as bioinsecticides for vector control without disturbing the natural ecosystem. Several studies have targeted mosquito genes at different developmental stages by the RNAi mechanism and result in vector control. In the present review, we included RNAi studies conducted for vector control by targeting mosquito genes at different developmental stages using different delivery methods. The review could help the researcher to find out novel genes of mosquitoes for vector control.
Render pests harmless – through genetic engineering CRISPR
25160Anonymous, Breaking Latest News, 2023-05-21 08:29:03.
Whether ants or wild bees: It is undisputed that insects are indispensable for functioning ecosystems and thus for the survival of mankind. In agriculture, however, certain species can become a nuisance. Even insecticides do not always help and also harm the environment. Researchers and companies are now pursuing a new strategy: Instead of treating plants, they want to defuse the harmful insects with the help of CRISPR gene scissors. “Before CRISPR/Cas, the technology to manipulate pests simply didn’t exist,” says Peter Atkinson, an entomologist at the University of California, Riverside, who works on modifying the invasive cicada species. “We are now entering a new era in which genetic control of the problem seems quite realistic.” It would not only be an alternative to the use of insecticides, but also a strategy to strengthen crop defenses through genetic engineering.
Near-infrared imaging for automated tsetse pupae sex sorting in support of the sterile insect technique
25472R. Argilés-Herrero, G. Salvador-Herranz, A. G. Parker, M. Zacarés, A. G. Fall, A. M. Gaye, A. Nawaz, P. Takáč, M. J. B. Vreysen and C. J. de Beer, Parasite, 30. 2023-05-17 08:49:45.
Tsetse flies are the cyclical vectors of African trypanosomes and one of several methods to manage this vector is the sterile insect technique (SIT). The ability to determine the sex of tsetse pupae with the objective to separate the sexes before adult emergence has been a major goal for decades for tsetse management programmes with an SIT component. Tsetse females develop faster and pharate females inside the pupae melanise 1–2 days before males. This earlier melanisation can be detected by infrared cameras through the pupal shell, and the newly developed Near InfraRed Pupae Sex Sorter (NIRPSS) takes advantage of this. The melanisation process is not homogeneous for all fly organs and the pupa needs to be examined ventrally, dorsally and laterally to ensure accurate classification by an image analysis algorithm. When the pupae are maturing at a constant temperature of 24 °C and sorted at the appropriate age, 24 days post-larviposition for Glossina palpalis gambiensis, the sorting machine can efficiently separate the sexes. The recovered male pupae can then be sterilised for field releases of males, while the rest of the pupae can be used to maintain the laboratory colony. The sorting process with the new NIRPSS had no negative impact on adult emergence and flight ability. A mean male recovery of 62.82 ± 3.61% was enough to provide sterile males to an operational SIT programme, while mean contamination with females (4.69 ± 3.02%) was low enough to have no impact on the maintenance of a laboratory colony
updated: Genetically Engineered Mosquitoes Research Authorization Application
25149California Department of Pesticide Regulation, California Department of Pesticide Regulation,, 2023-05-11 14:56:36.
In May 2023, Oxitec voluntarily withdrew its research authorization application to test the use of genetically engineered mosquitoes in California. DPR did not issue a decision on the application. For more information on Oxitec’s withdrawal and future plans for research in California, see their letter, PDF. The company applied for a research authorization from the department in March 2022 to release and study the use of genetically engineered Aedes aegypti mosquitoes to reduce the current Aedes aegypti mosquito population in Tulare County, California. DPR must approve a research authorization application before an unregistered pesticide can be field tested in the state. There is no pending research authorization or active application for the study of genetically engineered mosquitoes in California at this time.
Editorial: Genetic control of insect pest species—achievements, challenges, and perspectives
25423I. Häcker, D. Bartsch, A. Choo and F. Marec, Frontiers in Bioengineering and Biotechnology, 11. 2023-05-05 08:12:07.
Genetic control is a type ofbiological control and a promising approach to regulate insect pest populations in a species-specific manner. It is based on targeting the reproductive capacity of the target pest species to reduce population size to non-critical levels. The best known and also very successful genetic control strategy is the Sterile Insect Technique (SIT), which entails the continuous mass-release ofirradiation-sterilized males ofa given species to produce infertile matings in the field, leading to the decline in the target population over time. To date, SIT is only available for a few species, as its transfer to new target species is challenging and time consuming. Key aspects of this classical SIT and challenges in applying it to new pest species include mass rearing of target species, mass removal of female insects prior to irradiation and release, the sterilization procedure, and the biological quality control of the sterile insects produced. Besides this classical SIT strategy, current research efforts are also focused on the development of genetic control approaches based on transgenic, symbiont-mediated, or gene-drive strategies. Modern genetic technologies offer new solutions for the improvement of existing genetic control strategies and insect strains, for faster and easier transfer of existing strategies to new target species, and also for the development of new genetic control approaches. Publications within this Research Topic address pressing questions and challenges related to the genetic control of insect pests.
Mathematical modeling of the performance of wild and transgenic mosquitoes in malaria transmission
25861A. P. Wyse, A. J. B. dos Santos, J. D. Azevedo, A. C. de Meneses and V. M. D. Santos, Plos One, 18:23. 2023-04-28 08:20:19.
A mathematical model that simulates malaria transmission under the influence of transgenic mosquitoes refractory to malaria is presented in this paper. The zygosity of transgenic mosquitoes is taken into account and, consequently, the total population of mosquitoes is comprised of wild type and heterozygous and homozygous transgenic mosquitoes. These three mosquito varieties interact by mating and competition, and the genetic characteristics of their resulting offspring are in accordance with Mendelian genetics or the mutagenic chain reaction (MCR) technique. Although the incorporation of transgenic mosquitoes into the ecosystem reduces the incidence of malaria, the model also takes into account the importance of completing treatment in individuals with confirmed infection and the imminent risk of increased environmental temperature.
A rapidly spreading deleterious aphid endosymbiont that uses horizontal as well as vertical transmission
25082X. Gu, P. A. Ross, A. Gill, Q. Yang, E. Ansermin, S. Sharma, S. Soleimannejad, K. Sharma, A. Callahan, C. Brown, P. A. Umina, T. N. Kristensen and A. A. Hoffmann, Proceedings of the National Academy of Sciences, 120:e2217278120. 2023-04-24 06:34:04.
Endosymbiotic bacteria that live inside the cells of insects are typically only transmitted maternally and can spread by increasing host fitness and/or modifying reproduction in sexual hosts. Transinfections of Wolbachia endosymbionts are now being used to introduce useful phenotypes into sexual host populations, but there has been limited progress on applications using other endosymbionts and in asexual populations. Here, we develop a unique pathway to application in aphids by transferring the endosymbiont Rickettsiella viridis to the major crop pest Myzus persicae. Rickettsiella infection greatly reduced aphid fecundity, decreased heat tolerance, and modified aphid body color, from light to dark green. Despite inducing host fitness costs, Rickettsiella spread rapidly through caged aphid populations via plant-mediated horizontal transmission. The phenotypic effects of Rickettsiella were sensitive to temperature, with spread only occurring at 19 °C and not 25 °C. Body color modification was also lost at high temperatures despite Rickettsiella maintaining a high density. Rickettsiella shows the potential to spread through natural M. persicae populations by horizontal transmission and subsequent vertical transmission. Establishment of Rickettsiella in natural populations could reduce crop damage by modifying population age structure, reducing population growth and providing context-dependent effects on host fitness. Our results highlight the importance of plant-mediated horizontal transmission and interactions with temperature as drivers of endosymbiont spread in asexual insect populations.
Standardization of sterile insect technique (SIT) for melon fruit fly
25144M. Math and Y. K. Kotikal, Journal of Entomological Research, 47:16-20. 2023-04-21 14:26:32.
Sterile technique was standardized for melon fly, Zeugodacus cucurbitae Coquillett under laboratory conditions. The Adult emergence of B. cucurbitae was significantly highest (96.12%) without radiation to the pupae. Among different radiation doses, 30 Gy resulted in significantly the highest adult emergence (64.12%). Significantly the highest deformed adults were observed at 90 Gy (10.61%) while, it was lowest without radiation (1.33%). When mature pupae were exposed to 30, 50, 70 and 90 Gy the male longevity was 32.37, 26.55, 24.57 and 20.63 days, respectively, as against 34.98 days for untreated males. At 90 Gy mating competitive values recorded was 5.66 and 8.29 with a treated male: Untreated male: Untreated female cross ratio of 2:1:1 and 1:2:1, respectively. Significantly the highest per cent sterility of Z. cucurbitae was recorded at 90 Gy with a cross ratio of 2:1:1 and 1:1:2 (68.36 and 55.28%, respectively). © 2023, Journal of Entomological Research. All Rights Reserved.
Targeting Sex Determination to Suppress Mosquito Populations
24988L. Ming, P. K. Nikolay, S. Ruichen, Y. Ting, D. B. Elena, J. B. Daniel, A. Igor, M. S. C. Hector, Z. Yinpeng, A. D. Nicolas, M. L. YuMin, P. S. Matthew, M. Craig, M. M. John and S. A. Omar, bioRxiv, 2023.04.18.537404. 2023-04-20 14:45:03.
Each year, hundreds of millions of people are infected with arboviruses such as dengue, yellow fever, chikungunya, and Zika, which are all primarily spread by the notorious mosquito Aedes aegypti. Traditional control measures have proven insufficient, necessitating innovations. In response, here we generate a next generation CRISPR-based precision-guided sterile insect technique (pgSIT) for Aedes aegypti that disrupts genes essential for sex determination and fertility, producing predominantly sterile males that can be deployed at any life stage. Using mathematical models and empirical testing, we demonstrate that released pgSIT males can effectively compete with, suppress, and eliminate caged mosquito populations. This versatile species-specific platform has the potential for field deployment to control wild populations, safely curtailing disease transmission.Competing Interest StatementO.S.A. is a founder of Agragene, Inc. with equity interest. O.S.A., M.L., and N.P.K are founders of Synvect with equity interest. The terms of this arrangement have been reviewed and approved by the University of California, San Diego in accordance with its conflict of interest policies. All remaining authors declare no competing interests.
Spatial Distribution and Long-Term Persistence of Wolbachia-Infected Aedes aegypti in the Mentari Court, Malaysia
25100Y. L. Cheong, W. A. Nazni, H. L. Lee, A. NoorAfizah, I. C. MohdKhairuddin, G. M. R. Kamarul, N. M. N. Nizam, M. A. K. Arif, Z. M. NurZatilAqmar, S. M. Irwan, K. Khadijah, Y. M. Paid, O. Topek, A. H. Hasnor, R. AbuBakar, B. Singh Gill, K. Fadzilah, A. Tahi, Insects, 14. 2023-04-11 10:16:44.
Dengue is endemic in Malaysia, and vector control strategies are vital to reduce dengue transmission. The Wolbachia strain wAlbB carried by both sexes of Ae. aegypti was released in Mentari Court, a high-rise residential site, in October 2017 and stopped after 20 weeks. Wolbachia frequencies are still being monitored at multiple traps across this site, providing an opportunity to examine the spatiotemporal distribution of Wolbachia and mosquito density with respect to year, residential block, and floor, using spatial interpolation in ArcGIS, GLMs, and contingency analyses. In just 12 weeks, Wolbachia-infected mosquitoes were established right across the Mentari Court site with an overall infection frequency of >90%. To date, the Wolbachia frequency of Ae. aegypti has remained high in all areas across the site despite releases finishing four years ago. Nevertheless, the Wolbachia invaded more rapidly in some residential blocks than others, and also showed a relatively higher frequency on the eighth floor. The Ae. aegypti index tended to differ somewhat between residential blocks, whilst the Ae. albopictus index was relatively higher at the top and bottom floors of buildings. In Mentari Court, only a short release period was required to infiltrate Wolbachia completely and stably into the natural population. The results inform future releases in comparable sites in a dengue control programme.
Gamma-radiation of Glossina palpalis gambiensis revisited: effect on fertility and mating competitiveness
24993S. Pagabeleguem, O. Koughuindida, E. W. Salou, G. Gimonneau, A. I. Toé, B. A. Kaboré, K. S. M. Dera, H. Maïga, A. M. G. Belem, G. M. S. Sanou/Ouédraogo, M. J. Vreysen and J. Bouyer, Parasite, 30:8. 2023-03-31 14:58:29.
African animal trypanosomoses are vector-borne diseases that cause enormous livestock losses in sub-Saharan Africa, with drastic socio-economic impacts. Vector control in the context of an area-wide integrated pest management program with a sterile insect technique component requires the production of high-quality sterile male tsetse flies. In our study, we evaluated the effect of irradiation on the fecundity of Glossina palpalis gambiensis to identify the optimal dose that will induce maximum sterility while maintaining biological performance as much as possible. In addition, male mating performance was evaluated in semi-field cages. The irradiation doses used were 90, 100, 110, 120, 130, 140, and 150 Gy, and untreated males were used as the control. The results showed that pupal production and emergence rates were higher in batches of females that had mated with fertile males than in those that had mated with irradiated males with any experimental dose. A dose of 120 Gy administered to male flies induced 97-99% sterility after mating with virgin females. For the semi-field cage experiments, males irradiated with 120 Gy showed good sexual competitiveness as compared to fertile males and those irradiated with 140 Gy, considering the level of filling of spermatheca and the number of pairs formed. The optimal radiation dose of 120 Gy found in this study is slightly different from the traditional dose of 110 Gy that has been used in several eradication programmes in the past. The potential reasons for this difference are discussed, and an argument is made for the inclusion of reliable dosimetry systems in these types of studies.
Improved Quality Management of the Indian Meal Moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) for Enhanced Efficacy of the Sterile Insect Technique
25139M. M. Hasan, M. A. Hossain and C. G. Athanassiou, Insects, 14. 2023-03-31 14:15:48.
The sterile insect technique (SIT) is considered an environmentally friendly, autocidal control tactic to manage insect pests. This work dealt with the improvement of quality management of the Indian meal moth Plodia interpunctella (Hübner) for enhanced efficacy of the SIT. The results indicated that egg hatching of irradiated mature eggs of P. interpunctella was higher than that of younger eggs, indicating that mature eggs were significantly more tolerant than younger eggs. Moreover, our data revealed that a dose of 500 Gy completely prevented pupal formation in irradiated young and mature larvae. Crosses between irradiated and non-irradiated adults resulted in considerable variations in fecundity. The mating competitiveness index (CI) value was higher for a ratio of 5:1:1 (sterile male, fertile male, and fertile female, respectively) as compared with the ratio 1:1:1 for the irradiated individuals of all life stages. Low temperature (5 °C) maintenance of irradiated pupae significantly affected adult emergence. Using cylinders to assess flight ability, we found that the flight performance of adults that were developed from cold treated irradiated pupae was influenced by cylinder diameter, cylinder height and the number of hours the insects were in the cylinders. The percentage of DNA damage of the reproductive organs of adults developed from cold treated pupae that were irradiated with 100 and 150 Gy varied significantly. The results of this study should be used to implement pilot-scale field tests aiming at a sterile- to-fertile male ratio of 5 to 1. © 2023 by the authors.
Groundbreaking Partnership to Combat Dengue Mosquito in the Republic of the Marshall Islands Will Deploy Oxitec Friendly™ Aedes aegypti Solution
24918Oxitec, Oxitec.com, 2023-03-31 13:30:06.
The Republic of the Marshall Islands has selected Oxitec’s Friendly™ Aedes aegypti solution for a new pilot intervention to control the disease-spreading invasive Aedes aegypti mosquito. The project is a partnership between the Republic of the Marshall Islands, the Pacific Island Health Officers’ Association, the US Centers for Disease Control and Prevention, and Oxitec. Aedes aegypti has spread globally and is the primary vector of diseases such as dengue, Zika, chikungunya and yellow fever. Deployments of the Friendly™ Aedes aegypti are planned to be conducted on Ebeye Island where, in 2019, a severe dengue outbreak forced a 'State of Health emergency'.
The Promise and Challenge of Genetic Biocontrol Approaches for Malaria Elimination
24901S. James and M. Santos, Tropical Medicine and Infectious Disease, 2023-03-29 07:50:09.
Malaria remains an ongoing public health challenge, with over 600,000 deaths in 2021, of which approximately 96% occurred in Africa. Despite concerted efforts, the goal of global malaria elimination has stalled in recent years. This has resulted in widespread calls for new control methods. Genetic biocontrol approaches, including those focused on gene-drive-modified mosquitoes (GDMMs), aim to prevent malaria transmission by either reducing the population size of malaria transmitting mosquitoes or making the mosquitoes less competent to transmit the malaria parasite. The development of both strategies has advanced considerably in recent years, with successful field trials of several biocontrol methods employing live mosquito products and demonstration of the efficacy of GDMMs in insectary-based studies. Live mosquito biocontrol products aim to achieve area-wide control with characteristics that differ substantially from current insecticide-based vector control methods, resulting in some different considerations for approval and implementation. The successful field application of current biocontrol technologies against other pests provides evidence for the promise of these approaches and insights into the development pathway for new malaria control agents. The status of technical development as well as current thinking on the implementation requirements for genetic biocontrol approaches are reviewed, and remaining challenges for public health application in malaria prevention are discussed.
Vector competence of sterile male Glossina fuscipes fuscipes for Trypanosoma brucei brucei: implications for the implementation of the sterile insect technique in a sleeping sickness focus in Chad
24883M. H. Mahamat, A. Ségard, J.-B. Rayaisse, R. Argiles-Herrero, A. G. Parker, P. Solano, A. M. M. Abd-Alla, J. Bouyer and S. Ravel, Parasites and Vectors, 16:111. 2023-03-22 07:59:24.
Human African trypanosomiasis (HAT) is a neglected tropical disease caused by Trypanosoma brucei gambiense transmitted by tsetse flies in sub‑Saharan West Africa. In southern Chad the most active and persistent focus is the Mandoul focus, with 98% of the reported human cases, and where African animal trypanosomosis (AAT) is also present. Recently, a control project to eliminate tsetse flies (Glossina fuscipes fuscipes) in this focus using the sterile insect technique (SIT) was initiated. However, the release of large numbers of sterile males of G. f. fuscipes might result in a potential temporary increase in transmission of trypanosomes since male tsetse flies are also able to transmit the parasite. The objective of this work was therefore to experimentally assess the vector competence of sterile males treated with isometamidium for Trypanosoma brucei brucei.
Enhancing the scalability of Wolbachia-based vector-borne disease management: time and temperature limits for storage and transport of Wolbachia-infected Aedes aegypti eggs for field releases
24877M. J. Allman, Y. H. Lin, D. A. Joubert, J. Addley-Cook, M. C. Mejía-Torres, C. P. Simmons, H. A. Flores and J. E. Fraser, Parasit Vectors, 16:108. 2023-03-18 08:18:24.
BACKGROUND: Introgression of the bacterial endosymbiont Wolbachia into Aedes aegypti populations is a biocontrol approach being used to reduce arbovirus transmission. This requires mass release of Wolbachia-infected mosquitoes. While releases have been conducted using a variety of techniques, egg releases, using water-soluble capsules containing mosquito eggs and larval food, offer an attractive method due to its potential to reduce onsite resource requirements. However, optimisation of this approach is required to ensure there is no detrimental impact on mosquito fitness and to promote successful Wolbachia introgression. METHODS: We determined the impact of storage time and temperature on wild-type (WT) and Wolbachia-infected (wMel or wAlbB strains) Ae. aegypti eggs. Eggs were stored inside capsules over 8 weeks at 18 °C or 22 °C and hatch rate, emergence rate and Wolbachia density were determined. We next examined egg quality and Wolbachia density after exposing eggs to 4-40 °C to determine how eggs may be impacted if exposed to extreme temperatures during shipment. RESULTS: Encapsulating eggs for 8 weeks did not negatively impact egg viability or resulting adult emergence and Wolbachia density compared to controls. When eggs were exposed to temperatures within 4-36 °C for 48 h, their viability and resulting adult Wolbachia density were maintained; however, both were significantly reduced when exposed to 40 °C. CONCLUSIONS: We describe the time and temperature limits for maintaining viability of Wolbachia-infected Ae. aegypti eggs when encapsulated or exposed to extreme temperatures. These findings could improve the efficiency of mass releases by providing transport and storage constraints to ensure only high-quality material is utilised during field releases.
RNA interference is essential to modulating the pathogenesis of mosquito-borne viruses in the yellow fever mosquito Aedes aegypti
24948G. H. Samuel, T. Pohlenz, Y. Dong, N. Coskun, Z. N. Adelman, G. Dimopoulos and K. M. Myles, Proceedings of the National Academy of Sciences, 120:e2213701120. 2023-03-14 10:39:54.
While it has long been known that the transmission of mosquito-borne viruses depends on the establishment of persistent and nonlethal infections in the invertebrate host, specific roles for the insects? antiviral immune pathways in modulating the pathogenesis of viral infections is the subject of speculation and debate. Here, we show that a loss-of-function mutation in the Aedes aegypti Dicer-2 (Dcr-2) gene renders the insect acutely susceptible to a disease phenotype upon infection with pathogens in multiple virus families associated with important human diseases. Additional interrogation of the disease phenotype demonstrated that the virus-induced pathology is controlled through a canonical RNA interference (RNAi) pathway, which functions as a resistance mechanism. These results suggest comparatively modest contributions of proposed tolerance mechanisms to the fitness of A. aegypti infected with these pathogens. Similarly, the production of virus-derived piwi-interacting RNAs (vpiRNAs) was not sufficient to prevent the pathology associated with viral infections in Dcr-2 null mutants, also suggesting a less critical, or potentially secondary, role for vpiRNAs in antiviral immunity. These findings have important implications for understanding the ecological and evolutionary interactions occurring between A. aegypti and the pathogens they transmit to human and animal hosts.
Scientists disable protective gene in mosquitoes, making them susceptible to disease
24937Texas A&M University, Phys Org, 2023-03-14 10:09:07.
Immune pathways that protect mosquitoes from human pathogens, including West Nile, Zika and dengue viruses were disabled by Texas A&M AgriLife Research scientists. The research study, "RNA interference is essential to modulating the pathogenesis of mosquito-borne viruses in the yellow fever mosquito Aedes aegypti," published in the Proceedings of the National Academy of Sciences, showed that the mosquito vector species Aedes aegypti becomes acutely susceptible to disease when the protective immune pathway is disabled. This discovery provides new insight into the ecological and evolutionary interactions occurring between mosquitoes and the pathogens they transmit to humans and animals.
A male-killing gene encoded by a symbiotic virus of Drosophila
24838D. Kageyama, T. Harumoto, K. Nagamine, A. Fujiwara, T. N. Sugimoto, A. Jouraku, M. Tamura, T. K. Katoh and M. Watada, Nature Communications, 14:1357. 2023-03-13 08:49:35.
In most eukaryotes, biparentally inherited nuclear genomes and maternally inherited cytoplasmic genomes have different evolutionary interests. Strongly female-biased sex ratios that are repeatedly observed in various arthropods often result from the male-specific lethality (male-killing) induced by maternally inherited symbiotic bacteria such as Spiroplasma and Wolbachia. However, despite some plausible case reports wherein viruses are raised as male-killers, it is not well understood how viruses, having much smaller genomes than bacteria, are capable of inducing male-killing. Here we show that a maternally inherited double-stranded RNA (dsRNA) virus belonging to the family Partitiviridae (designated DbMKPV1) induces male-killing in Drosophila. DbMKPV1 localizes in the cytoplasm and possesses only four genes, i.e., one gene in each of the four genomic segments (dsRNA1−dsRNA4), in contrast to ca. 1000 or more genes possessed by Spiroplasma or Wolbachia. We also show that a protein (designated PVMKp1; 330 amino acids in size), encoded by a gene on the dsRNA4 segment, is necessary and sufficient for inducing male-killing. Our results imply that male-killing genes can be easily acquired by symbiotic viruses through reassortment and that symbiotic viruses are hidden players in arthropod evolution. We anticipate that host-manipulating genes possessed by symbiotic viruses can be utilized for controlling arthropods.
CRISPR-based genetic control strategies for insect pests
24978Y. Yan, R. A. Aumann, I. Hacker and M. F. Schetelig, Journal of Integrative Agriculture, 22:651-668. 2023-03-11 07:53:08.
Genetic control strategies such as the sterile insect technique have successfully fought insect pests worldwide. The CRISPR (clustered regularly interspaced short palindromic repeats) technology, together with high-quality genomic resources obtained in more and more species, greatly facilitates the development of novel genetic control insect strains that can be used in area-wide and species-specific pest control programs. Here, we review the research progress towards state-of-art CRISPR-based genetic control strategies, including gene drive, sex ratio distortion, CRISPR-engineered genetic sexing strains, and precision-guided sterile insect technique. These strategies' working mechanisms, potential resistance development mechanisms, and regulations are illustrated and discussed. In addition, recent developments such as stacked and conditional systems are introduced. We envision that the advances in genetic technology will continue to be one of the driving forces for developing the next generation of pest control strategies.
Development of transgenic corn planthopper Peregrinus maidis that express the tetracycline transactivator
27707A. A. Patil, W. Klobasa, D. Espinoza-Rivera, O. Baars, M. D. Lorenzen and M. J. Scott, Insect Molecular Biology, 32:363-375. 2023-02-24 09:39:46.
Abstract The corn planthopper, Peregrinus maidis, is a vector of several maize viruses and is consequently a significant agricultural pest in many tropical and subtropical regions. As P. maidis has developed resistance to insecticides, the aim of this study was to develop transgenic P. maidis strains that could be used for future genetic biocontrol programs. To facilitate the identification of transgenic P. maidis, we isolated and characterized the promoters for the P. maidis ubiquitin-like and profilin genes. Transient expression assays with P. maidis embryos showed that both promoters were active. Transgenic lines were established using piggyBac vectors and fluorescent protein marker genes. The lines carried an auto-regulated tetracycline transactivator (tTA) gene, which has been widely used to establish conditional lethal strains in other insect species. The transgenic lines showed low levels of tTA expression but were viable on diet with or without doxycycline, which inhibits the binding of tTA to DNA. We discuss possible modifications to the tTA overexpression system that could lead to the successful development of conditional lethal strains. To our knowledge, this is the first report of a transgenic Hemiptera. The approach we have taken could potentially be applied to other Hemiptera and, for P. maidis, the technology will facilitate future functional genomics studies.
Will new genetic engineering tech finally eliminate malaria?
24747Anonymous, Business Daily, 2023-02-20 19:03:20.
Richard Mukabana, a senior research and policy analyst at African Institute for Development Policy, says the technology which employs the principle of sending a thief to catch a thief may yet prove the most effective. “It is only a mosquito that knows where another mosquito is and it’s easier for it to search for others and kill them through suppression,” says Prof Mukabana. In gene drive technologies, an artificial gene is introduced into the malaria-transmitting mosquito population. This then disrupts reproduction by either distorting sex chromosome inheritance such that most offspring are males, or by knocking out female fertility genes such that they no longer lay eggs. Experts argue that the current technology used in fighting malaria, which comprises vector control and drug therapy has not been sufficiently adequate to eliminate the disease on the continent, hence the need to embrace new technologies.
White-Eyed Fruit Flies: How Improvements in Gene Editing Could Aid in Pest Managemen
24752C. Bernhardt, Entomology Today, 2023-02-17 19:07:21.
The SIT involves scientists raising the target fruit fly species in the lab, sterilizing the flies by exposing them to a certain amount of radiation while they are still pupae, and releasing large amounts of the newly sterile flies into nature. When the released, sterile flies mate with wild flies, they produce infertile eggs that never hatch and, over time, this reduces—and hopefully eliminates—the population of flies. “But research shows that if you only release sterile males—instead of sterile males and females at the same time—you can more efficiently accomplish management,” says Daniel Paulo, PhD, a researcher in the Department of Plant and Environmental Protection Sciences at the University of Hawaiʻi at Mānoa. Male flies mate more often than females and don’t damage fruits in the field because they don’t lay eggs. Male-focused SIT programs also guarantee sterile males are using their energy to mate with wild-type females, not with females who were also sterilized. So, scientists target male flies with sterilization efforts by using a classic genetic method called genetic sexing, which helps create sex-specific, visible physical characteristics or markers (called phenotypes) among fruit flies. These phenotypes make it possible for scientists to tell the two sexes apart more easily and parse the males and females before sterilizing. A colony of such flies is called genetic sexing strain (GSS). A GSS requires a phenotype scientists can create by inducing a genetic change, called a mutation, that leads to a visible characteristic. Next, they link the normal, non-mutated visual marker to the male sex.
How genomics can help biodiversity conservation
24754K. Theissinger, C. Fernandes, G. Formenti, I. Bista, P. R. Berg, C. Bleidorn, A. Bombarely, A. Crottini, G. R. Gallo, J. A. Godoy, S. Jentoft, J. Malukiewicz, A. Mouton, R. A. Oomen, S. Paez, P. J. Palsbøll, C. Pampoulie, M. J. Ruiz-López, S. Secomandi, H, Trends in Genetics, 2023-02-16 19:11:36.
Genomics provides effective tools to characterize biodiversity, but the full implementation of genomic techniques in practical conservation is still limited. We review some of the main approaches in biodiversity genomics available to conservationists and genomicists.High-quality, long-read sequencing and bioinformatic technologies facilitate genome sequencing and assembly for any species. We summarize how reference genomes, in conjunction with population genomic data, can contribute to biodiversity monitoring, conservation, and restoration efforts.Over the past decade, many initiatives to generate reference genomes spanning the tree of life have emerged worldwide. We call for increased integration of reference genomes and population genomics data into interdisciplinary conservation efforts to fully unlock the potential of genomics in safeguarding global biodiversity.
Gene Drive: Past, Present and Future Roads to Vertebrate Biocontrol
24780G. R. McFarlane, C. B. A. Whitelaw and S. G. Lillico, Applied Biosciences, 2:52-70. 2023-02-13 09:35:36.
Scientists have long sought a technology to humanely control populations of damaging invasive pests in a species-specific manner. Gene drive technology could see this become a reality. This review charts the twists and turns on the road to developing gene drives in vertebrates. We focus on rodents, as these will likely be the first targets, and trace the journey from the early understanding of selfish genetic elements to engineering gene drives in mice; before discussing future research focuses and the crucial role that public perception and governance will play in the application of this technology. The realisation of robust gene drive strategies in vertebrate pests has the potential to revolutionise biocontrol.
A Zika virus-responsive sensor-effector system in Aedes aegypti
24699S. Basu, C. M. Reitmayer, S. Lumley, B. Atkinson, M. L. Schade-Weskott, S. Rooney, W. Larner, E. E. Montiel, R. Gutierrez-Lopez, E. Levitt, H. M. Munyanduki, A. M. E. Elrefaey, A. T. Clarke, S. Koit, E. Zusinaite, R. Fragkoudis, A. Merits and L. Alphey, bioRxiv, 2023.02.06.527261. 2023-02-06 12:38:46.
Zika virus (ZIKV) is a recently re-emerged flavivirus transmitted primarily through the bite of an infected mosquito, Aedes aegypti being the main vector. ZIKV infection is associated with a range of adverse effects; infection during pregnancy can lead to foetal abnormalities, including microcephaly. Lacking a licensed vaccine, or specific therapeutics, control of ZIKV transmission focuses on vector control. However, in most transmission settings, current methods are insufficient to successfully control ZIKV, or other similarly-transmitted arboviruses such as dengue and chikungunya viruses. This has stimulated interest in genetics-based methods, either to reduce the number of mosquitoes (population suppression), or to make mosquitoes less able to transmit (population modification). Here, we describe a method to selectively eliminate infected mosquitoes, using a virus sensor inserted into the mosquito genome and coupled to a quorum-counting lethal effector. In mosquitoes, ZIKV normally establishes persistent, lifelong infection; survival of these infected mosquitoes is crucial to transmission potential. Correspondingly, removal of infected mosquitoes can reduce vectorial capacity of a mosquito population, i.e. ability to transmit. Since relatively few mosquitoes become infected, typically <2%, engineered hypersensitivity to ZIKV would have only a modest population-level fitness cost, and lower still if transmission were successfully reduced by such means.Competing Interest StatementThe authors have declared no competing interest.
How CRISPR could help save crops from devastation caused by pests
24675E. F. Merchant, MIT Technology Review, 2023-02-02 10:23:26.
Researchers are now looking to add cutting-edge technology to California’s anti-Pierce’s arsenal, by changing the genome of the glassy-winged sharpshooter so that it can no longer spread the bacterium. Such a solution is possible thanks to CRISPR gene-editing technology, which has made modifying the genes of any organism increasingly simple. The technique has been used in experiments in cancer immunotherapy, apple breeding, and—controversially—human embryos. Now a growing number of researchers are applying it to agricultural pests, aiming to control a range of insects that together destroy about 40% of global crop production each year. If successful, these efforts could reduce reliance on insecticides and provide an alternative to genetic modifications to crops. For now, these gene-edited insects are shut away in labs across the globe, but that is poised to change. This year, a US company expects to start greenhouse tests in conjunction with the US Department of Agriculture (USDA) of fruit-damaging insects made sterile using CRISPR. At the same time, scientists at government and private institutions are beginning to learn more about pest genetics and to make edits in more species.
Biological comparative study between Wolbachia-infected Aedes aegypti mosquito and Wolbachia-uninfected strain, Jeddah city, Saudi Arabia
24804A. G. Algamdi, F. M. Shaher and J. A. Mahyoub, Saudi J Biol Sci, 30:103581. 2023-02-02 08:32:08.
In this study, samples of Wolbachia-infected Aedes aegypti mosquitoes were collected from Al-Safa district in Jeddah city, Saudi Arabia. The presence of Wolbachia bacteria in mosquitoes was confirmed by PCR technique and they were reared and propagated in the laboratory. Comparative studies were conducted between Wolbachia-infected A. Aegypti and the Wolbachia-uninfected laboratory strain in terms of their ability to withstand drought, resist two types of insecticides and the activities of pesticide detoxification enzymes. The Wolbachia-infected A. aegypti strain proved less able to withstand the drought period, as the egg-hatching rate of the Wolbachia-uninfected strain was greater than that of the Wolbachia-infected strain after one, two and three months of dry periods. Compared to the Wolbachia-uninfected strain, the Wolbachia-infected strain demonstrated a relatively greater resistance to tested pesticides, namely Baton 100EC and Fendure 25EC which may be attributed to the higher levels of the detoxification enzymes glutathione-S-transferase and catalase and the lower levels of esterase and acetylcholine esterase.
Imperial startup Biocentis to develop genetic tech to control harmful insects
24673D. Silverman, Imperial College London, 2023-02-01 10:17:53.
The Imperial startup was founded in 2022 by Imperial researchers in partnership with technology-focused investment group Neurone to create a more effective and sustainable alternative to pesticides. While insects play an essential role in the global ecosystem, among the planet’s millions of insect species are some that spread devastating human diseases such as Dengue Fever and Zika virus, exacerbate food insecurity by spoiling up to 25% of crops, and reduce biodiversity by invading new ecosystems to the detriment of local species. At present, these harmful insect populations are controlled primarily with pesticides. But the growth of pesticide resistance is prompting control programmes to increase the dose and frequency of the toxic chemicals, causing increasing harm to bees and other non-target species.
Engineered Antiviral Sensor Targets Infected Mosquitoes
24617E. Dalla Benetta, A. J. Lopez-Denman, H.-H. Li, R. A. Masri, D. J. Brogan, M. Bui, T. Yang, M. Li, M. Dunn, M. J. Klein, S. Jackson, K. Catalan, K. R. Blasdell, P. Tng, I. Antoshechkin, L. S. Alphey, P. N. Paradkar and O. Akbari, bioRxiv, 2023.01.27.525922. 2023-01-27 09:22:47.
Escalating vector disease burdens pose significant global health risks, so innovative tools for targeting mosquitoes are critical. We engineered an antiviral strategy termed REAPER (vRNA Expression Activates Poisonous Effector Ribonuclease) that leverages the programmable RNA-targeting capabilities of CRISPR Cas13 and its potent collateral activity. Akin to a stealthy Trojan Horse hiding in stealth awaiting the presence of its enemy, REAPER remains concealed within the mosquito until an infectious blood meal is up taken. Upon target viral RNA infection, REAPER activates, triggering programmed destruction of its target arbovirus such as chikungunya. Consequently, Cas13 mediated RNA targeting significantly reduces viral replication and its promiscuous collateral activity can even kill infected mosquitoes. This innovative REAPER technology adds to an arsenal of effective molecular genetic tools to combat mosquito virus transmission.Competing Interest StatementO.S.A is a founder of both Agragene, Inc. and Synvect, Inc. with equity interest. The terms of this arrangement have been reviewed and approved by the University of California, San Diego in accordance with its conflict of interest policies. L.A is an adviser to Synvect, Inc and Biocentis Ltd., with financial interest in each. All other authors declare no competing interests.
Control of Aedes mosquito populations using recombinant microalgae expressing short hairpin RNAs and their effect on plankton
24615X. Fei, S. Xiao, X. Huang, Z. Li, X. Li, C. He, Y. Li, X. Zhang and X. Deng, PLOS Neglected Tropical Diseases, 17:e0011109. 2023-01-26 09:15:48.
New biocontrol strategies are urgently needed to combat vector-borne infectious diseases. This study presents a low-cost method to produce a potential mosquito insecticide that utilizes the microalgae released into suburban water sources to control mosquito populations. Chlorella microalgae are ubiquitous in local waters, which were chosen as the host for genetic transfection. This species facilitated the recombinant algae to adapt to the prevailing environmental conditions with rapid growth and high relative abundance. The procedure involved microalgae RNAi-based insecticides developed using short hairpin RNAs targeting the Aedes aegypti chitin synthase A (chsa) gene in Chlorella. These insecticides effectively silenced the chsa gene, inhibiting Aedes metamorphosis in the laboratory and simulatedfield trials. This study explored the impact of recombinant microalgae on the phytoplankton and zooplankton in suburban waters. High-throughput sequencing revealed that rapid reproduction of recombinant Chlorella indirectly caused the disappearance of some phytoplankton and reduced the protozoan species. This study demonstrated that a recombinant microalgae-based insecticide could effectively reduce the population of Aedes mosquitoes in the laboratory and simulated field trials. However, the impact of this technology on the environment and ecology requires further investigation.
Closing the gap to effective gene drive in Aedes aegypti by exploiting germline regulatory elements
24581M. A. E. Anderson, E. Gonzalez, J. X. D. Ang, L. Shackleford, K. Nevard, S. A. N. Verkuijl, M. P. Edgington, T. Harvey-Samuel and L. Alphey, Nature Communications, 14:338. 2023-01-20 09:00:46.
CRISPR/Cas9-based homing gene drives have emerged as a potential new approach to mosquito control. While attempts have been made to develop such systems in Aedes aegypti, none have been able to match the high drive efficiency observed in Anopheles species. Here we generate Ae. aegypti transgenic lines expressing Cas9 using germline-specific regulatory elements and assess their ability to bias inheritance of an sgRNA-expressing element (kmo(sgRNAs)). Four shu-Cas9 and one sds3-Cas9 isolines can significantly bias the inheritance of kmo(sgRNAs), with sds3G1-Cas9 causing the highest average inheritance of ~86% and ~94% from males and females carrying both elements outcrossed to wild-type, respectively. Our mathematical model demonstrates that sds3G1-Cas9 could enable the spread of the kmo(sgRNAs) element to either reach a higher (by ~15 percentage point) maximum carrier frequency or to achieve similar maximum carrier frequency faster (by 12 generations) when compared to two other established split drive systems.
Joint FAO/IAEA Coordinated Research Project on Mosquito Handling, Transport, Release and Male Trapping Methods in Support of SIT Application to Control Mosquitoes
24566M. Gómez, B. J. Johnson, H. C. Bossin and R. Argilés-Herrero, Insects, 14. 2023-01-19 08:14:17.
The research carried out in the framework of this CRP generated key achievements in areas relevant to the SIT application to control mosquitoes. Among these outcomes, particular mentions must be given to the following: (1) Novel and efficient self-marking techniques were established to improve our understanding of male movement, competitiveness, survival, and potential interaction with closely related species post-release [7,8]. As the next step, these new marking systems will be upscaled and validated under operational conditions in SIT field projects targeting the Aedes species. (2) One of the techniques evaluated included the novel large-scale marking of male mosquitoes via administration of Rhodamine B via sugar feeding. The mentioned technique brings the advantage of marking all of the tissues of the mosquitoes, including sperm and seminal fluid, such that the mark can be retrieved and identified in mated females. Thus, the use of Rhodamine B enables researchers to estimate the sexual competitiveness of sterile male mosquitoes under field conditions [9,10].
Biotech company released 2.4 billions GM Mosquitoes in two parts of the U.S
24346C. Victorial, NEWSBREAK, 2022-12-27 16:20:57.
Due to the high death rate that mosquitoes have inflicted, The Environmental Protection Agency (EPA) has approved the release of 2.4 billion genetically modified mosquitoes in selected regions of California and Florida. These modified mosquitoes were created by a biotechnology company called Oxitec. The technology creates non-biting Aedes aegypti, which are common invasive types of mosquito. The males are engineered to only produce other male offspring. Oxitec states that the process will greatly reduce the number mosquitoes, as female mosquitoes are expected to die, while males will reproduce and spread the self-limiting gene to the next upcoming generation. The goal is to eventually decrease the population of all mosquitos to regulated state.
Gene drive designs for efficient and localisable population suppression using Y-linked editors
24339R. Geci, K. Willis and A. Burt, PLOS Genetics, 18:e1010550. 2022-12-27 08:45:03.
Author summary Some pest populations can be successfully controlled by the inundative release of sterile males, but this approach is not practicable when the target population is large or the species difficult to rear. Computer modelling has previously demonstrated that releasing males with a genomic editor on their Y chromosome that kills or sterilises female descendants could be much more efficient, particularly if combined with a sex ratio distorter. Here we extend this work to show that Y-linked editors can also be used in even more efficient gene drive designs that would spread over successive generations beyond the region of release. Such spread could nonetheless be controlled by exploiting relatively small pre-existing differences in gene frequency between populations to restrict the spread and impact of the constructs, if desired. The proposed design does not require high rates of recombinational repair of DNA breaks or expression off the Y chromosome during meiosis, potentially expanding the range of species in which such low release rate control is possible. Y-linked editors may therefore form the basis of a highly flexible set of genetic strategies for population control.
Use of Insect Promoters in Genetic Engineering to Control Mosquito-Borne Diseases
24584V. Bottino-Rojas and A. A. James, Biomolecules, 13. 2022-12-22 10:33:51.
Mosquito transgenesis and gene-drive technologies provide the basis for developing promising new tools for vector-borne disease prevention by either suppressing wild mosquito populations or reducing their capacity from transmitting pathogens. Many studies of the regulatory DNA and promoters of genes with robust sex-, tissue- and stage-specific expression profiles have supported the development of new tools and strategies that could bring mosquito-borne diseases under control. Although the list of regulatory elements available is significant, only a limited set of those can reliably drive spatial-temporal expression. Here, we review the advances in our ability to express beneficial and other genes in mosquitoes, and highlight the information needed for the development of new mosquito-control and anti-disease strategies.
Good news in the fight against vector-borne diseases
24175K. Magori, 2022-12-09 11:07:13.
At the turn of the century, several research groups attempted to apply modern genetic methodologies to achieve similar outcomes without the need for irradiation and the resulting fitness costs. Luke Alphey and his colleagues at Oxford University developed a dominant lethal genetic system for autocidal control in the Mediterranean fruitfly, where a transactivator causes lethality in the early developmental stages of heterozygous insects unless repressed by tetracycline. The company he funded (Oxitec Limited) successfully adapted this system in several agriculturally important pest species, as well as in Aedes aegypti and other mosquitoes. (Full disclosure: I worked at Oxitec Limited in 2007, but own no shares or have any other conflict of interest with them). While the first generation of these mosquitoes proved to successfully reduce wild-type mosquito populations, they required labor-intensive separation of male and female mosquitoes before release in close proximity. While this ensured that only non-biting male mosquitoes are released, it also limited the scalability of this approach.
Tolerance-conferring defensive symbionts and the evolution of parasite virulence
24126C. A. Smith and B. Ashby, bioRxiv, 2022-12-05 09:03:54.
Defensive symbionts in the host microbiome can confer protection from infection or reduce the harms of being infected by a parasite. Defensive symbionts are therefore promising agents of biocontrol that could be used to control or ameliorate the impact of infectious diseases. Previous theory has shown how symbionts can evolve along the parasitism-mutualism continuum to confer greater or lesser protection to their hosts, and in turn how hosts may coevolve with their symbionts to potentially form a mutualistic relationship. However, the consequences of introducing a defensive symbiont for parasite evolution and how the symbiont may coevolve with the parasite have yet to be explored theoretically. Here, we investigate the ecological and evolutionary implications of introducing a tolerance-conferring defensive symbiont into an established host-parasite system. We show that while the defensive symbiont may initially have a positive impact on the host population, parasite and symbiont evolution tend to have a net negative effect on the host population in the long-term. This is because the introduction of the defensive symbiont always selects for an increase in parasite virulence and may cause diversification into high- and low-virulence strains. Even if the symbiont experiences selection for greater host protection, this simply increases selection for virulence in the parasite, resulting in a net negative effect on the host population. Our results therefore suggest that tolerance-conferring defensive symbionts may be poor biocontrol agents for population-level infectious disease control.Competing Interest StatementThe authors have declared no competing interest.
Does severe hypoxia during irradiation of Aedes aegypti pupae improve sterile male performance?
24069D. A. Tussey, K. J. Linthicum and D. A. Hahn, Parasites and Vectors, 15:446. 2022-11-28 10:25:24.
The yellow fever mosquito, Aedes aegypti, vectors several pathogens responsible for human diseases. As a result, this mosquito species is a priority for control by mosquito control districts in Florida. With insecticide resistance development becoming a concern, alternative control strategies are needed for Ae. aegypti. Sterile insect technique (SIT) is an increasingly popular option that is being explored as a practical area-wide control method. However, questions about sterile male performance persist. The objectives of this study were to determine the extent to which hypoxia exposure prior to and during irradiation effects the longevity, activity and mating competitiveness of sterile male Ae. aegypti.
Should NZ use contentious gene tech in our war on pests?
24032J. Morton, NZ Herald, 2022-11-27 09:45:02.
Gene-altering technology could offer “breakthrough opportunities” for saving our pest-threatened species, a new future-scoping report says, but there’d be some tricky issues to address before it’d be a realistic option. Scientists have already been exploring how these contentious tools - among several areas canvassed in a new future-focused briefing by the Department of Conservation and Land Information New Zealand - might aid our ongoing war on pest predators. But it’s doubtful that would happen anytime soon, given the tech isn’t yet ready, and the Government has little appetite toward making law changes that’d likely be needed to unleash it in our environment. The briefing, just put out for public feedback, explained how gene-editing tools like Crispr-Cas9 could be used to change particular genes or introduce new traits.
Turns Out Fighting Mosquitoes With Mosquitoes Actually Works
24018E. Mullin, Wired, 2022-11-21 08:56:57.
In the Brazilian city of Indaiatuba, an effort is underway to eliminate these pests before they have a chance to spread illness. The weapon: more Aedes aegypti mosquitoes—but ones genetically engineered to kill their own kind. Made by British biotechnology firm Oxitec, the mosquitoes seem to be working. The modified mosquitoes carry a synthetic self-limiting gene that prevents female offspring from surviving. This is important, because only the females bite and transmit disease. In a new study, scientists at the company showed that their engineered insects were able to slash the local population of Aedes aegypti by up to 96 percent over 11 months in the neighborhoods where they were released. “This is an area with high levels of Aedes aegypti, and they periodically have outbreaks of dengue,” says Nathan Rose, head of malaria programs at Oxitec. In fact, this summer the Brazilian Ministry of Health reported that dengue fever was continuing to spread in all five regions of the country. Between January 1 and May 31, Brazil had more than 1.1 million cases—an increase of 198 percent compared to the same period in 2021. In those five months, the disease, which causes high fever, rash, and muscle and joint pain, killed 504 people. For the study, which was conducted in 2018 and 2019, the company chose four densely populated neighborhoods with high levels of Aedes aegypti. In two, scientists released a “dose” of 100 male mosquitoes per resident per week. In the others, they cranked that up to 500.
Should we use a genetic weapon against mosquitoes carrying malaria?
23988T. H. Saey, ScienceNewsExplores, 2022-11-17 08:58:08.
In a large laboratory cage, a male mosquito carries a genetic weapon that could launch the destruction of his species. That loss could also mean the end of the parasite that causes malaria. The weapon? A self-replicating bit of DNA known as a gene drive. It’s one of the most anticipated tools being developed to stop mosquitoes from spreading diseases like malaria to humans. It’s also one of the most controversial. The gene drive interferes with the insects’ ability to reproduce. In one small lab study, it wiped out captive populations of mosquitoes in just eight to 12 generations. A larger study in outdoor cages in Terni, Italy, worked too. Within as little as five to 10 years, this gene drive could be ready to test in the wild. Researchers are eyeing Africa for the first test release. There, malaria takes a huge toll. In 2020, it sickened close to 241 million people on the continent. And most of the globe’s 670,000 malaria deaths that year were in Africa. About eight in every 10 were children, the World Health Organization says. Many tools have been made to fight the disease. There are preventive drugs, insecticide-treated bed nets and even vaccines. These efforts are helping. But mosquitoes are developing resistance to insecticides. And some anti-malaria drugs may no longer work well. “To go toward zero [cases], we need to have something that is transformational,” says Fredros Okumu. By that, he means a completely new type of strategy. Okumu is a mosquito biologist. He directs science programs at Ifakara Health Institute in Tanzania, a country in East Africa. Gene drives might be the big change people are looking for. This technology was first devised in 2015. Researchers are still refining and testing it. Other types of genetically altered mosquitoes have been released in Brazil, the United States and elsewhere. But so far, those altered genes spread slowly among wild populations. Gene drives could potentially spread to nearly every member of a species quickly. In this way, they could forever alter the species. Or even wipe it out.
Health experts meet in Dar over use of GMO mosquitoes to fight Malaria
23991M. Chelangat, NATION, 2022-11-16 09:03:01.
Regional health think thanks led by the African Institute for Development and Policy (AFIDEP), East African Community(EAC) Health department, East African Health Research Commission and Ifakara health institute will be meeting in Dar es Salaam, Tanzania for three day starting tomorrow to discuss the development of genetically modified mosquitoes to help in controlling and eliminating malaria.The experts will also be discussing regulatory reforms and policies, given that regulatory frameworks of many African countries do not provide clear guidance on how to develop and test genetically modified mosquitoes. According to the Centers for Disease Control and Prevention (CDC), genetically modified mosquitoes are mass produced in a laboratory to carry two types of genes.
Gene drive technology to suppress invasive mice
23843University of Adelaide, Phys Org, 2022-11-09 09:55:57.
Researchers at the University of Adelaide have released their first findings on the potential effectiveness of revolutionary gene drive technology to control invasive mice. The team has developed a world-first proof of concept for the technology—called t-CRISPR—using laboratory mice. Using sophisticated computer modeling performed by co-first author Dr. Aysegul Birand, the researchers also found about 250 gene-modified mice could eradicate an island population of 200,000 mice in around 20 years. The results of the study have been published today in Proceedings of the National Academy of Sciences.
Calif. Legislature bites back at GE mosquito releases
23866L. Patrick, Sun Gazette, 2022-11-08 10:15:50.
A biotech company created millions of genetically modified mosquitoes, but not in the Jurassic Park sense. The lab grown species could actually lower the population of an invasive mosquito that carries a plethora of diseases on its shoulders.On Nov. 3, several members of the California legislature sent a letter to the Department of Pesticide Regulation (DPR) asking it to delay the release of millions of genetically engineered (GE) mosquitoes in Tulare County by Oxitec, a British biotech company, in the interest of further regulatory review. The GE mosquitoes are meant to lower the population of Aedes aegypti, an invasive mosquito that has been plaguing communities in the county for the last few years. However, members of the legislature are pushing for the DPR to resist the GE mosquitoes because of unforeseen effects they might have on people and the environment. This would be the first experimental release of of the non-biting mosquitoes, which OxiTec calls “friendly mosquitoes,” in Tulare County. Though the U.S. Environmental Protection Agency approved the release of the mosquitoes on March 7, the agency has been awaiting approval from DPR for several months, even after a 15-month scientific evaluation process and a 15-day public comment period that ended on April 19.
Leveraging a natural murine meiotic drive to suppress invasive populations
23835L. Gierus, A. Birand, M. D. Bunting, G. I. Godahewa, S. G. Piltz, K. P. Oh, A. J. Piaggio, D. W. Threadgill, J. Godwin, O. Edwards, P. Cassey, J. V. Ross, T. A. A. Prowse and P. Q. Thomas, Proceedings of the National Academy of Sciences, 119:e2213308119. 2022-11-08 09:36:13.
Invasive rodents are a major cause of environmental damage and biodiversity loss, particularly on islands. Unlike insects, genetic biocontrol strategies including population-suppressing gene drives with biased inheritance have not been developed in mice. Here, we demonstrate a gene drive strategy (t(CRISPR)) that leverages super-Mendelian transmission of the t haplotype to spread inactivating mutations in a haplosufficient female fertility gene (Prl). Using spatially explicit individual-based in silico modeling, we show that t(CRISPR) can eradicate island populations under a range of realistic field-based parameter values. We also engineer transgenic t(CRISPR) mice that, crucially, exhibit biased transmission of the modified t haplotype and Prl mutations at levels our modeling predicts would be sufficient for eradication. This is an example of a feasible gene drive system for invasive alien rodent population control.
A sterile insect technique pilot trial on Captiva Island: defining mosquito population parameters for sterile male releases using mark–release–recapture
23818D. O. Carvalho, R. Morreale, S. Stenhouse, D. A. Hahn, M. Gomez, A. Lloyd and D. Hoel, Parasites and Vectors, 15:405. 2022-11-01 10:41:32.
The sterile insect technique (SIT), which involves area-wide inundative releases of sterile insects to suppress the reproduction of a target species, has proven to be an effective pest control method. The technique demands the continuous release of sterilized insects in quantities thatThe sterile insect technique (SIT), which involves area-wide inundative releases of sterile insects to suppress the reproduction of a target species, has proven to be an effective pest control method. The technique demands the continuous release of sterilized insects in quantities that ensure a high sterile male:wild male ratio for the suppression of the wild population over succeeding generations. Over the course of seven mark-release-recapture studies using single- and multiple-point releases, 190,504 sterile marked males were released, for which the recapture rate was 1.5% over a mean period of 12 days. The mean distance traveled by sterile males of the local strain of Ae. aegypti that has colonized Captiva Island was 201.7 m from the release point, with an observed maximum traveled distance of 404.5 m. The released sterile mosquitoes had a probability of daily survival of 0.67 and an average life expectancy of ~ 2.46 days.s These data together with the population size estimate and sterile:wild ratio provide a solid basis for planning the SIT operational phase which is aimed at mosquito population suppression. ensure a high sterile male:wild male ratio for the suppression of the wild population over succeeding generations.
Genetically modified mosquitoes cut the insect’s number by 96 per cent
23812M. Fauzia, NewScientist, 2022-10-31 09:18:00.
The release of genetically modified male mosquitoes into a city in Brazil temporarily cut the virus-carrying insects by up to 96 per cent. Although not a permanent fix, periodically releasing such mosquitoes could reduce the burden of infections including dengue, malaria and Zika. Kevin Gorman at the biotechnology firm Oxitec in Abingdon, UK, and his colleagues are particularly looking to control dengue. Although usually mild, the infection can be fatal. Already widespread …
Expression of mosquito miRNAs in entomopathogenic fungus induces pathogen-mediated host RNA interference and increases fungal efficacy
23853C. Cui, Y. Wang, Y. Li, P. Sun, J. Jiang, H. Zhou, J. Liu and S. Wang, Cell Reports, 41:111527. 2022-10-25 10:15:50.
Summary The growing threat of insecticide resistance prompts the urgent need to develop additional tools for mosquito control. Entomopathogenic fungi provide an eco-friendly alternative to chemical insecticides. One limitation to the use of mycoinsecticides is their relatively low virulence. Here, we report an approach for suppressing mosquito immunity and increasing fungal virulence. We engineered Beauveria bassiana to express Aedes immunosuppressive microRNAs (miRNAs) to induce host RNA interference (RNAi) immune responses. We show that engineered strains can produce and deliver the miRNAs into host cells to activate cross-kingdom RNAi during infection and suppress mosquito immunity by targeting multiple host genes, thereby dramatically increasing fungal virulence against Aedes aegypti and Galleria mellonella larvae. Importantly, expressing host miRNAs also significantly increases fungal virulence against insecticide-resistant mosquitoes, creating potential for insecticide-resistance management. This pathogen-mediated RNAi (pmRNAi)-based approach provides an innovative strategy to enhance the efficacy of fungal insecticides and eliminate the likelihood of resistance development.
Cross-kingdom RNAi to enhance the efficacy of insect pathogens
23851S. Asgari, Trends in Parasitology, 2022-10-25 10:11:07.
Insect pathogens play significant roles in the biocontrol of medical and agricultural pests. Cui et al. demonstrated that genetically modified (GM) fungi expressing host mosquito miRNAs could enhance the efficacy of the fungus by suppressing the host immune response. This opens avenues for utilisation of cross-kingdom RNAi in biocontrol.
Combining transgenesis with paratransgenesis to fight malaria
23802W. Huang, J. Vega-Rodriguez, C. Kizito, S.-J. Cha and M. Jacobs-Lorena, eLife, 11:e77584. 2022-10-25 06:30:55.
Malaria is among the deadliest infectious diseases, and Plasmodium, the causative agent, needs to complete a complex development cycle in its vector mosquito for transmission to occur. Two promising strategies to curb transmission are transgenesis, consisting of genetically engineering mosquitoes to express antimalarial effector molecules, and paratransgenesis, consisting of introducing into the mosquito commensal bacteria engineered to express antimalarial effector molecules. Although both approaches restrict parasite development in the mosquito, it is not known how their effectiveness compares. Here we provide an in-depth assessment of transgenesis and paratransgenesis and evaluate the combination of the two approaches. Using the Q-system to drive gene expression, we engineered mosquitoes to produce and secrete two effectors – scorpine and the MP2 peptide – into the mosquito gut and salivary glands. We also engineered Serratia, a commensal bacterium capable of spreading through mosquito populations to secrete effectors into the mosquito gut. Whereas both mosquito-based and bacteria-based approaches strongly reduced the oocyst and sporozoite intensity, a substantially stronger reduction of Plasmodium falciparum development was achieved when transgenesis and paratransgenesis were combined. Most importantly, transmission of Plasmodium berghei from infected to naïve mice was maximally inhibited by the combination of the two approaches. Combining these two strategies promises to become a powerful approach to combat malaria.
Zombie Deer and the Scientists Behind the War on the ‘Man Eater’
24023S. Jones, NC STATE CALS News, 2022-10-24 09:52:07.
In the remote jungles of the Panama-Colombia border, sterile flesh-eating flies fall from the sky in the thousands. Released from retired military planes, they embark on a suicide mission for their species, with the sole purpose of duping their female counterparts into mating with them despite their inability to bear offspring. Before this military-like operation became the norm, the New World Screwworm (Cochliomyia hominivorax or “man-eater”) cost livestock producers millions of dollars every year as a merciless parasite. Without scientific intervention, the screwworm’s life cycle weaves a devastating tale fit for classic horror films of a bygone era. After a successful rendezvous with a male screwworm, the female screwworm spends her time drinking the sweet nectar of the forest. When she’s ready to lay her eggs, she emerges from the forest and into nearby farms and pastures on the hunt for a suitable host. Then she spots it: a blissfully grazing cow who just so happens to have a scratch on its head. She lands in the wound, lays her eggs and waits for another generation of screwworms to do its worst, which doesn’t take long. This devilish pest has completely adapted to a parasitic lifestyle, with its eggs developing in a matter of hours at the precise body temperature of a poor unsuspecting cow. “They develop at 40 degrees Celsius, which is really hot for most insects. Most flies won’t develop well at that temperature. These do, and they’re very quick,” says Max Scott, Professor of Entomology at North Carolina State University’s Department of Entomology and Plant Pathology.
Driving down malaria transmission with engineered gene drives
23780W. T. Garrood, P. Cuber, K. Willis, F. Bernardini, N. M. Page and R. E. Haghighat-Khah, Frontiers in Genetics, 13. 2022-10-19 07:08:43.
The last century has witnessed the introduction, establishment and expansion of mosquito-borne diseases into diverse new geographic ranges. Malaria is transmitted by female Anopheles mosquitoes. Despite making great strides over the past few decades in reducing the burden of malaria, transmission is now on the rise again, in part owing to the emergence of mosquito resistance to insecticides, antimalarial drug resistance and, more recently, the challenges of the COVID-19 pandemic, which resulted in the reduced implementation efficiency of various control programs. The utility of genetically engineered gene drive mosquitoes as tools to decrease the burden of malaria by controlling the disease-transmitting mosquitoes is being evaluated. To date, there has been remarkable progress in the development of CRISPR/Cas9-based homing endonuclease designs in malaria mosquitoes due to successful proof-of-principle and multigenerational experiments. In this review, we examine the lessons learnt from the development of current CRISPR/Cas9-based homing endonuclease gene drives, providing a framework for the development of gene drive systems for the targeted control of wild malaria-transmitting mosquito populations that overcome challenges such as with evolving drive-resistance. We also discuss the additional substantial works required to progress the development of gene drive systems from scientific discovery to further study and subsequent field application in endemic settings.
Why we need to talk about ‘gene-drive’ grey squirrels
23778Anonymous, University of Exeter, 2022-10-17 07:04:37.
Would the best way of controlling the UK’s rampant grey squirrel population be to spread genetic changes throughout the species? A new research film, to be shown next month at Exeter Phoenix, sees scientists, conservation and wildlife experts debate the use of emergent ‘gene-drive’ technology in grey squirrels. The film Should we create gene drive grey squirrels?, written and produced by Sarah Hartley, a Professor in Technology Governance at the University of Exeter Business School, and independent film-maker Tom Law, documents the introduction into the UK of grey squirrels at the turn of the 20th Century and how their burgeoning population has contributed to the demise of the UK’s native red squirrel, which is now mainly found in Scotland. It presents the reasons why some people argue it would be better to limit the grey squirrel population, including the fact that they carry and spread squirrel pox, a virus fatal to red squirrels which can devastate entire populations.
Mosquito Gene Drives and the Malaria Eradication Agenda
23731Editor: R. Carballar-Lejarazu,, Jenny Stanford Publishing, 2022-10-17 06:37:46.
Malaria is one of most serious infectious diseases today and has afflicted humankind for thousands of years. A significant number of people still die from this mosquito-borne disease, despite the use of various malaria prevention and control methods over hundreds of years and more than a century of coordinated global control efforts using modern tools, together with research into and development of new strategies for prevention, diagnosis, and disease treatment. Genetic approaches that focus on the vector mosquitoes to prevent malaria parasite transmission have been considered for many decades. Genetic control strategies received a significant boost with the successful development of gene-drive systems, genetic methods for rapidly spreading beneficial genes and phenotypes through mosquito populations. This book reviews some concepts of gene drive systems and describes pioneering applications to control mosquito populations and prevent parasite transmission.
GeneConvene Global Collaborative Webinar Series | Wolbachia Biology, Mechanisms and Applications 2022
23723David O'Brochta, GeneConvene Global Collaborative, 2022-10-15 06:57:26.
Intracellular and extracellular symbiotic/commensal bacteria have enormous potential when manipulated and deployed appropriately to serve as agents of control of insects and the pathogens they transmit. Wolbachia, an intracellular bacteria, is a well studied system and one that is used increasingly to control insect populations via cytoplasmic incompatibility and to alter the vectoral capacity of insect via pathogen inhibition. This webinar series will survey the applications of Wolbachia as a mosquito/dengue control intervention and the underlying biology that conditions its effectiveness.
Combating Mosquito-Borne Diseases with CRISPR
23701N. Spahich, The Scientist, 2022-10-11 08:06:34.
Female mosquitoes are some of the deadliest organisms in the world due to their ability to spread infectious diseases through a simple bite. Mosquito-borne diseases such as yellow fever, Zika, Dengue fever, and malaria kill millions of humans every year, and there are limited therapeutics for their prevention and treatment. While in college, Omar Akbari worked as a public service intern testing the local mosquito population for human pathogens and eradicating these insects with chemicals. During this experience, he felt dissatisfied with the insecticide-based method of controlling mosquito population and wanted to find a better way to tackle the problem of mosquito-borne disease spread. With a multidisciplinary team in his laboratory at the University of California, San Diego, he now develops tools through genetic engineering techniques such as CRISPR to solve the world’s insect control problems.
Points to consider in seeking biosafety approval for research, testing, and environmental release of experimental genetically modified biocontrol products during research and development
23648W. K. Tonui, V. Ahuja, C. J. Beech, J. B. Connolly, B. Dass, D. C. M. Glandorf, et al., Transgenic Research, 31:607. 2022-10-04 08:24:50.
Novel genetically modified biological control products (referred to as “GM biocontrol products”) are being considered to address a range of complex problems in public health, conservation, and agriculture, including preventing the transmission of vector-borne parasitic and viral diseases as well as the spread of invasive plant and animal species. These interventions involve release of genetically modified organisms (GMOs) into the environment, sometimes with intentional dissemination of the modification within the local population of the targeted species, which presents new challenges and opportunities for regulatory review and decision-making. Practices developed for GMOs, primarily applied to date for GM crops may need to be adapted to accommodate different types of organisms, such as insects, and different technologies, such as gene drive. Developers of new GM biocontrol products would benefit from an early understanding of safety data and information that are likely to be required within the regulatory dossier for regulatory evaluation and decision making. Here a generalizable tool drawing from existing GM crop dossier requirements, forms, and relevant experience is proposed to assist researchers and developers organize and plan their research and trialing. This tool requires considering specifics of each investigational product, their intended use, and country specific requirements at various phases of potential product development, from laboratory research through contained field testing and experimental release into the environment. This may also be helpful to risk assessors and regulators in supporting their systematic and rigorous evaluation of new biocontrol products.
Humans Have a Long History of Making ‘Very Bad Decisions’ to Save Animals
23627T. McDonnell, The New York Times, 2022-09-17 07:17:21.
Environmental reporter Tim McDonnell on the potential negative consequences of animal conservation efforts. McDonnell highlights Target Malaria’s research on gene drive to “eliminate malaria-carrying mosquitos” and quotes New Zealand researcher Philipp Messer saying that the world is “ill-prepared” for a "real-life gene drive.” The article also quotes MIT biologist Kevin Esvelt saying that misuse of the technology would cause the public and policymakers to halt gene drive research and would set the field back by a decade. The article notes that there is no international regulation to “prevent the premature deployment of gene drive in the wild” and states that “individual governments, powerful funding organizations like the Bill and Melinda Gates Foundation, and scientists themselves” are responsible for balancing the prevention of risky interventions with the need to support basic research. Esvlet is also quoted saying that the WHO needs to “establish a registry for all gene drive experiments that requires scientists to detail safeguards and find a local community who agrees to guide the research before experiments begin.”
Can a bold new plan to stop mosquitoes catch on?
23631L. J. Young, Popular Science, 2022-09-13 07:48:42.
In the northwestern outskirts of Visalia in Tulare County, California, Bryan Ruiz drives down a familiar dirt road that cuts through farmland. He comes up to an irrigation pipe that’s created a “pretty nasty” situation—a small patch of vegetation and algae-covered water baking under the early June sun. As his shadow looms over the pool, a wormlike critter less than half an inch long quickly tries to submerge out of sight, but before it can, Ruiz scoops it up with a long metal dipper. He squints at his catch: a larva of Culex, a genus that includes common house mosquitoes.
Fact Check: Bill Gates’ genetically modified mosquitoes are responsible for mosquito-borne viruses in Florida and are part of the next planned pandemic.
23542A. Williams, The Paradise, 2022-09-09 06:00:08.
The genetically modified mosquitoes in Florida are part of a project by Oxitec that Bill Gates did not fund. The virus reported in Florida is the West Nile virus, which has had reported cases in most U.S. states since 1999, with lower cases in 2022 than in previous years. The virus has no correlation to the release of the mosquitoes by Oxitec, and no reports have mentioned they have caused harm. The belief that pandemics are planned by governmental or global business is a known conspiracy and unsubstantiated. Therefore, this claim has been marked as false.
Bill Gates’ Colombian Mosquito Factory Breeding 30 Million Bacteria-Infected Mosquitos Per Week
23525anonymous, GREATGAMEINDIA, 2022-09-07 05:27:22.
Bill Gates’ Colombian ‘mosquito factory’ is breeding 30 million bacteria-infected mosquitos per week. The project’s objective appears to be to introduce Wolbachia into native mosquito populations by employing lab-bred mosquitoes, resulting in the infection of such populations. In a plant in Colombia, Bill Gates is currently producing 30 million bacterially-infected mosquitoes every week and he has threatened to “scale and deliver” the mosquitoes to “communities around the world.” As part of his World Mosquito Program (WMP), the Microsoft founder and self-declared World Health Czar has already invested $185 million in the establishment of the mosquito factory. What is the project’s stated purpose? In order to eradicate native mosquito populations thought to be responsible for dengue, zika, and other viral illnesses in humans, it is necessary to utilize mosquitoes that are infected with a bacteria that induces sterility.
An evaluation of fusion partner proteins for paratransgenesis in Asaia bogorensis
24274C. Grogan, M. Bennett and D. J. Lampe, Plos One, 17:18. 2022-09-01 14:11:14.
Mosquitoes transmit many pathogens responsible for human diseases, such as malaria which is caused by parasites in the genus Plasmodium. Current strategies to control vector-transmitted diseases are increasingly undermined by mosquito and pathogen resistance, so additional methods of control are required. Paratransgenesis is a method whereby symbiotic bacteria are genetically modified to affect the mosquito's phenotype by engineering them to deliver effector molecules into the midgut to kill parasites. One paratransgenesis candidate is Asaia bogorensis, a Gram-negative bacterium colonizing the midgut, ovaries, and salivary glands of Anopheles sp. mosquitoes. Previously, engineered Asaia strains using native signals to drive the release of the antimicrobial peptide, scorpine, fused to alkaline phosphatase were successful in significantly suppressing the number of oocysts formed after a blood meal containing P. berghei. However, these strains saw high fitness costs associated with the production of the recombinant protein. Here, we report evaluation of five different partner proteins fused to scorpine that were evaluated for effects on the growth and fitness of the transgenic bacteria. Three of the new partner proteins resulted in significant levels of protein released from the Asaia bacterium while also significantly reducing the prevalence of mosquitoes infected with P. berghei. Two partners performed as well as the previously tested Asaia strain that used alkaline phosphatase in the fitness analyses, but neither exceeded it. It may be that there is a maximum level of fitness and parasite inhibition that can be achieved with scorpine being driven constitutively, and that use of a Plasmodium specific effector molecule in place of scorpine would help to mitigate the stress on the symbionts.
A confinable female-lethal population suppression system in the malaria vector, Anopheles gambiae
23500A. L. Smidler, J. J. Pai, R. A. Apte, H. M. Sánchez C, R. M. Corder, E. J. Gutiérrez, N. Thakre, I. Antoshechkin, J. M. Marshall and O. S. Akbari, bioRxiv, 2022.08.30.505861. 2022-08-30 19:10:47.
Malaria is among the world’s deadliest diseases, predominantly affecting sub-Saharan Africa, and killing over half a million people annually. Controlling the principal vector, the mosquito Anopheles gambiae, as well as other anophelines, is among the most effective methods to control disease spread. Here we develop an innovative genetic population suppression system termed Ifegenia (Inherited Female Elimination by Genetically Encoded Nucleases to Interrupt Alleles) in this deadly vector. In this bicomponent CRISPR-based approach, we disrupt a female-essential gene, femaleless (fle), demonstrating complete genetic sexing via heritable daughter gynecide. Moreover, we show that Ifegenia males remain reproductively viable, and can load both fle mutations and CRISPR machinery to induce fle mutations in subsequent generations, resulting in sustained population suppression. Through modeling, we demonstrate that iterative releases of non-biting Ifegenia males can act as an effective, confinable, controllable, and safe population suppression and elimination system.
Rational engineering of a synthetic insect-bacterial mutualism
23473Y. Su, H.-C. Lin, L. S. Teh, F. Chevance, I. James, C. Mayfield, K. G. Golic, J. A. Gagnon, O. Rog and C. Dale, Current Biology, 2022-08-29 07:21:11.
Summary Many insects maintain mutualistic associations with bacterial endosymbionts, but little is known about how they originate in nature. In this study, we describe the establishment and manipulation of a synthetic insect-bacterial symbiosis in a weevil host. Following egg injection, the nascent symbiont colonized many tissues, including prototypical somatic and germinal bacteriomes, yielding maternal transmission over many generations. We then engineered the nascent symbiont to overproduce the aromatic amino acids tyrosine and phenylalanine, which facilitate weevil cuticle strengthening and accelerated larval development, replicating the function of mutualistic symbionts that are widely distributed among weevils and other beetles in nature. Our work provides empirical support for the notion that mutualistic symbioses can be initiated in insects by the acquisition of environmental bacteria. It also shows that certain bacterial genera, including the Sodalis spp. used in our study, are predisposed to develop these associations due to their ability to maintain benign infections and undergo vertical transmission in diverse insect hosts, facilitating the partner-fidelity feedback that is critical for the evolution of obligate mutualism. These experimental advances provide a new platform for laboratory studies focusing on the molecular mechanisms and evolutionary processes underlying insect-bacterial symbiosis.
Biologists engineered insect-bacterial mutualism in ‘bucket list’ achievement
23475Annonymous, @THEU, 2022-08-23 07:28:20.
A new paper in Current Biology authored by Crystal Su and other collaborators in the School of Biological Sciences describes the development of a novel, synthetic insect-bacterial symbiosis that is sustained through many insect generations by transovarial bacterial transmission. The symbiotic bacteria express a red fluorescent protein that is visible through the insect cuticle, facilitating characterization of the mechanics of infection and transmission in insect tissues and cells. In addition, Su et. al.engineered the bacteria to modify their ability to synthesize aromatic amino acids, which are used by the insect host to fuel cuticle strengthening. Correspondingly, insects maintaining bacteria that overproduce these nutrients exhibited stronger cuticles, signifying mutualistic function. The establishment of this synthetic symbiosis will facilitate detailed molecular genetic analysis of symbiotic interactions and presents a foundation for the use of genetically modified symbionts in the engineering of insects that transmit diseases of medical and agricultural importance. The paper is titled “Rational engineering of a synthetic insect-bacterial mutualism.”
Genetic Tools for Integrated Management of Pests on Honeybees in the Tropics
25464M. Pattabhiramaiah, S. Mallikarjunaiah and D. Brueckner, Genetic Methods and Tools for Managing Crop Pests, 2022-08-22 09:48:31.
The Asian honeybee is endemic to Asia where it has been used for honey production and pollination services from time immemorial. They are integral to modern agricultural productivity and to survival and vitality of natural ecosystems. However, recent declines in populations and species diversity threaten both food security and natural habitats. Honeybee colonies are assaulted by numerous pests and pathogens including mites and beetles. Novel, cost-effective pest management practices are desperately needed to preserve colony health. Increased pest pressure levels justify the need for additional control methods. Beekeepers should follow the guidelines of integrated pest management (IPM) as an effective control option that will have a minimum impact on honeybee health. The use of genomic tools and engineering technologies has a great potential for enhancement and sustenance of the health of honeybees. This review focusses on the application of innovative advanced genetic tools such as SIT (sterile insect technique), genome editing, gene drive, RNAi, CRISPR/Cas9-mediated gene editing, and gene pyramiding in honeybee pest management.
CRISPR, an eco-friendly technology, may detect crop pests
23460W. Adam, list23, 2022-08-22 09:16:51.
Drosophila suzukii, an invading insect pest, is a threat to agricultural yields, especially to the production of fruits such as strawberries, cherries, plums, and grapes in western countries. Until now, control measures to stop the spread of D. suzukii have been inadequate. A research published in GEN Biotechnology (Precision Guided Sterile Males Suppress Populations of an Invasive Crop Pest) describes the development of a programmable CRISPR-based technique that might, if implemented at large in the wild, eliminate fertile male D. suzukii, effectively, specifically, and safely controlling this pest population. The team at the University of California, San Diego (UCSD) implemented a temperature-inducible, precision-guided, sterile insect technique (pgSIT), described by the team in an earlier investigation, to breed infertile but fit D. suzukii males with modest shorter lifespans. Through empirical experimentation and mathematical modeling, the researchers demonstrated that repeated release of sterilized males can rapidly and successfully eliminate D. suzukii populations.
World Mosquito Day: Can genetic modification techniques quash the menace?
23446CNBCTV18, CNBC TV18, 2022-08-20 09:54:03.
Genetically modified (GM) mosquitoes are prepared in labs and are supposed to fight the Aedes aegypti mosquitoes which spread viruses including dengue, Zika, and chikungunya. Billions have apparently been successfully released in the US, Brazil, the Cayman Islands, Panama, and India.
Outbreaks of arboviruses, biotechnological innovations and vector control: facing the unexpected
23438C. Boëte, Innovative Strategies for Vector Control, 6:219-231. 2022-08-19 09:19:15.
Outbreaks of arboviruses have occurred in the last decades in many places around the world and a variety of responses have been taken in order to control them. Responses ranged from vaccination campaigns to the use of conventional vector control methods. Innovative approaches relying on biotechnological novelties, often still under development, have been considered despite the lack of solid evidence of their efficacy. While discussing these different aspects of the fight against vector-borne diseases with a focus on the context of outbreaks, this chapter considers the social and ethical aspects related to both the rhetoric and the discussion about the implementation of new and innovative approaches.
Precision Guided Sterile Males Suppress Populations of an Invasive Crop Pest
23453N. P. Kandul, J. Liu, A. Buchman, I. C. Shriner, R. M. Corder, N. Warsinger-Pepe, T. Yang, A. K. Yadav, M. J. Scott, J. M. Marshall and O. S. Akbari, GEN Biotechnology, 1:372-385. 2022-08-18 10:24:32.
The Drosophila suzukii invasion of western countries has created an immense agricultural and economic threat to crop production. Despite many attempts to suppress its population, D. suzukii continues to destroy soft-flesh fruits. Precision guided sterile insect technique (pgSIT) utilizes the accuracy of programmable CRISPR gene targeting to generate sterilized males that can be deployed to suppress populations. Here, we generate pgSIT in D. suzukii and empirically and mathematically demonstrate that sterilized males are fit, competitive, and can eliminate populations of D. suzukii. Altogether, we describe an efficient way to generate sterile D. suzukii for release and safe effective population suppression.
CRISPR-based technology targets global crop pest
23449University of California - San Diego, Phys Org, 2022-08-18 10:05:07.
Applying new CRISPR-based technology to a broad agricultural need, researchers at the University of California San Diego have set their aims on a worldwide pest known to decimate valuable food crops. Nikolay Kandul, Omar Akbari and their colleagues first demonstrated the precision-guided sterile insect technique, or pgSIT, in Drosophila melanogaster, the common fruit fly, in 2019. The technology, later adapted to mosquitoes, uses programmable CRISPR techniques to edit key genes that control sex determination and fertility. Under the new system, pgSIT-developed insect eggs are deployed into a targeted population and only sterile males hatch, resulting in a fertility dead end for that species. Kandul, Akbari and their colleagues have now adapted the technology for use in Drosophila suzukii, an invasive fruit fly (also known as the spotted-wing drosophila) responsible for millions of dollars in crop damage. The advancement is described in the journal GEN Biotechnology.
Environmentally appropriate vector control is facilitated by standard metrics for simulation-based evaluation
23443V. N. Vásquez, M. R. Reddy and J. M. Marshall, Frontiers in Tropical Diseases, 3. 2022-08-17 08:44:11.
As anthropogenic factors contribute to the introduction and expansion of new and established vector species, the geographic incidence of mosquito-borne disease is shifting. Computer simulations, informed by field data where possible, facilitate the cost-effective evaluation of available public health interventions and are a powerful tool for informing appropriate policy action. However, a variety of measurements are used in such assessments; this can complicate direct comparisons across both vector control technologies and the models used to simulate them. The expansion of biocontrol to include genetically engineered organisms is now prompting additional metrics with no analogy to traditional measurement approaches. We propose Standard Entomological Metrics (SEMs) to facilitate the model-based appraisal of both existing and novel intervention tools and define two examples: Suppression Efficacy Score and Time to Reduction Target. We formulate twelve synthetic case studies featuring two vector control technologies over three years of observed daily temperature in Cairns, Australia. After calculating Suppression Efficacy Score and Time to Reduction Target results, we apply these example outcomes to a discussion of health policy decision-making using SEMs. We submit that SEMs such as Suppression Efficacy Score and Time to Reduction Target facilitate the wholistic and environmentally appropriate simulation-based evaluation of intervention programs and invite the community to further discussion on this topic.
Changing mosquito genes, spreading bacteria: Science sees success vs dengue
23421C. E. Baclig, INQUIRER.NET, 2022-08-10 08:51:03.
Wolbachia, according to WMP, are extremely common bacteria that occur naturally in 50 percent of insect species, including mosquitoes, fruit flies, moths, dragonflies, and butterflies. Aedes aegypti or dengue-carrying mosquitoes, however, do not normally carry Wolbachia. Studies showed that the bacteria make it difficult for viruses, such as dengue, Zika, chikungunya, and yellow fever, to reproduce inside the Aedes aegypti mosquitoes—making the mosquitoes much less likely to spread viruses when they bite people. “This means that when Aedes aegypti mosquitoes carry natural Wolbachia bacteria, the transmission of viruses like dengue, Zika, chikungunya, and yellow fever is reduced,” the organization explained. The WMP breeds Wolbachia-carrying mosquitoes and releases them into areas hit by mosquito-borne diseases. This means there will be “less risk of disease in communities where Wolbachia is established in the local mosquito population.”
Aedes aegypti and Ae. albopictus microbiome/virome: new strategies for controlling arboviral transmission?
23413M. Gómez, D. Martinez, M. Muñoz and J. D. Ramírez, Parasites and Vectors, 15:287. 2022-08-09 12:21:12.
Aedes aegypti and Aedes albopictus are the main vectors of highly pathogenic viruses for humans, such as dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV), which cause febrile, hemorrhagic, and neurological diseases and remain a major threat to global public health. The high ecological plasticity, opportunistic feeding patterns, and versatility in the use of urban and natural breeding sites of these vectors have favored their dispersal and adaptation in tropical, subtropical, and even temperate zones. Due to the lack of available treatments and vaccines, mosquito population control is the most effective way to prevent arboviral diseases. Resident microorganisms play a crucial role in host fitness by preventing or enhancing its vectorial ability to transmit viral pathogens. High-throughput sequencing and metagenomic analyses have advanced our understanding of the composition and functionality of the microbiota of Aedes spp. Interestingly, shotgun metagenomics studies have established that mosquito vectors harbor a highly conserved virome composed of insect-specific viruses (ISV). Although ISVs are not infectious to vertebrates, they can alter different phases of the arboviral cycle, interfering with transmission to the human host. Therefore, this review focuses on the description of Ae. aegypti and Ae. albopictus as vectors susceptible to infection by viral pathogens, highlighting the role of the microbiota-virome in vectorial competence and its potential in control strategies for new emerging and re-emerging arboviruses.
Reflection on the Challenges, Accomplishments, and New Frontiers of Gene Drives
23416M. Melesse Vergara, J. Labbé and J. Tannous, BioDesign Research, 2022:9853416. 2022-08-09 07:29:59.
Ongoing pest and disease outbreaks pose a serious threat to human, crop, and animal lives, emphasizing the need for constantgenetic discoveries that could serve as mitigation strategies. Gene drives are genetic engineering approaches discovered decadesago that may allow quick, super-Mendelian dissemination of genetic modifications in wild populations, offering hopes formedicine, agriculture, and ecology in combating diseases. Following itsfirst discovery, several naturally occurring selfishgenetic elements were identified and several gene drive mechanisms that could attain relatively high threshold populationreplacement have been proposed. This review provides a comprehensive overview of the recent advances in gene drive researchwith a particular emphasis on CRISPR-Cas gene drives, the technology that has revolutionized the process of genomeengineering. Herein, we discuss the benefits and caveats of this technology and place it within the context of natural genedrives discovered to date and various synthetic drives engineered. Later, we elaborate on the strategies for designing syntheticdrive systems to address resistance issues and prevent them from altering the entire wild populations. Lastly, we highlight themajor applications of synthetic CRISPR-based gene drives in different living organisms, including plants, animals, andmicroorganisms.
Sterility of Cydia pomonella by X ray irradiation as an alternative to gamma radiation for the sterile insect technique
23463J.-H. Zhang, N. Li, H.-Y. Zhao, Y.-Q. Wang, X.-Q. Yang and K.-M. Wu, Bulletin of Entomological Research, 2022-08-06 09:27:59.
The codling moth Cydia pomonella is a major pest of global significance impacting pome fruits and walnuts. It threatens the apple industry in the Loess Plateau and Bohai Bay in China. Sterile insect technique (SIT) could overcome the limitations set by environmentally compatible area-wide integrated pest management (AW-IPM) approaches such as mating disruption and attract-kill that are difficult to suppress in a high-density pest population, as well as the development of insecticide resistance. In this study, we investigated the effects of X-ray irradiation (183, 366, 549 Gy) on the fecundity and fertility of a laboratory strain of C. pomonella, using a newly developed irradiator, to evaluate the possibility of X-rays as a replacement for Cobalt60 (60Co-γ) and the expanded future role of this approach in codling moth control. Results show that the 8th-day is the optimal age for irradiation of male pupae. The fecundity decreased significantly as the dosage of radiation increased. The mating ratio and mating number were not influenced. However, treated females were sub-sterile at a radiation dose of 183 Gy (20.93%), and were almost 100% sterile at a radiation dose of 366 Gy or higher. Although exposure to a radiation dose of 366 Gy resulted in a significant reduction in the mating competitiveness of male moths, our radiation biology results suggest that this new generation of X-ray irradiator has potential applications in SIT programs for future codling moth control.
Studies on the fitness characteristics of wMel- and wAlbB-introgressed Aedes aegypti (Pud) lines in comparison with wMel- and wAlbB-transinfected Aedes aegypti (Aus) and wild-type Aedes aegypti (Pud) lines
23485C. Sadanandane, K. Gunasekaran, D. Panneer, S. K. Subbarao, M. Rahi, B. Vijayakumar, V. Athithan, A. Sakthivel, S. Dinesh and P. Jambulingam, Frontiers in Microbiology, 13:947857. 2022-08-05 07:02:55.
Wolbachia, an intracellular maternally transmitted endosymbiont, has been shown to interfere with the replication of dengue virus in Aedes aegypti mosquitoes. The Wolbachia-transinfected Ae. aegypti has been currently released in many countries to test its effectiveness in preventing the transmission of dengue virus. ICMR-Vector Control Research Centre in collaboration with World Mosquito Program Monash University, Australia, has generated two new Wolbachia-introgressed Ae. aegypti Puducherry (Pud) lines via backcrossing Ae. aegypti females of Australian (Aus) strains, infected with wMel and wAlbB Wolbachia with wild-type Ae. aegypti Puducherry (Pud) males. Wolbachia infections are known to induce a fitness cost and confer benefit on the host mosquito populations that will influence spread of the Wolbachia into native wild mosquito populations during the field release. Hence, the induced fitness cost or benefit/advantage in the two newly generated Ae. aegypti (Pud) lines was assessed in the laboratory in comparison with the wild-type Ae. aegypti (Pud) strain. In addition, maternal transmission (MT) efficiency, induced cytoplasmic incompatibility (CI), and insecticide resistance status of the two (Pud) lines were determined to assess the likely frequency of wMel and wAlbB infections in the native wild population after field invasion. The study shows that wMel and wAlbB infections did not induce any fitness cost on the two newly generated (Pud) lines. Rather, in terms of wing length, fecundity, egg hatch rate, and adult survival, the Wolbachia introgression conferred fitness benefits on the (Pud) lines compared to uninfected Wolbachia free wild Ae. aegypti population. wMel and wAlbB exhibited a high maternal transmission (99-100%) and induced nearly complete (98-100%) cytoplasmic incompatibility. Both the (Pud) lines were resistant to deltamethrin, malathion, DDT, and temephos, and the level of resistance was almost the same between the two lines as in the wild type. Overall, the stable association of wMel and wAlbB established with Ae. aegypti and the reproductive advantages of the (Pud) lines encourage a pilot release in the field for population replacement potential.
Release the Beast? Genetically modified mosquitos for diease control
23351G. Ferrante, Palatinate, 2022-07-29 08:31:10.
The company Oxitec is an example how genetic technologies can be used in managing unwanted species in a sustainable way.Oxitec jumped to the headlines in March with permits being issued by the United States Environmental Protection Agency (EPA) to allow the release of around 2.4 billion male mosquitos over two years in Florida and California. This is part of an expansion of their existing trial of releasing a genetically modified mosquito species in a bid to suppress the species Aedes aegypti in the USA. Aedes aegypti also known as the yellow fever mosquito has a main role in spreading debilitating diseases such as Dengue, Chikungunya, Yellow Fever and Zika virus in many countries. Aedes aegypti also is an invasive species in many subtropical regions, spanning from the south-eastern US to the Pacific Islands and South-East Asia. Oxitec’s signature technology involves the use of a ‘self-limiting’ gene which only activates in female mosquitos after reproduction.
Robust control strategy by the Sterile Insect Technique for reducing epidemiological risk in presence of vector migration
23331P.-A. Bliman and Y. Dumont, Mathematical Biosciences, 350:108856. 2022-07-28 08:36:35.
The Sterile Insect Technique (SIT) is a promising technique to control mosquitoes, vectors of diseases, like dengue, chikungunya or Zika. However, its application in the field is not easy, and its success hinges upon several constraints, one of them being that the treated area must be sufficiently isolated to limit migration or re-invasion by mosquitoes from the outside. In this manuscript we study the impact of males and (fertile) females migration on SIT. We show that a critical release rate for sterile males exists for every migration level, in the context of continuous or periodic releases. In particular, when (fertile) females migration is sufficiently low, then SIT can be conducted successfully using either open-loop control or closed-loop control (or a combination of both methods) when regular measurements of the wild population are completed. Numerical simulations to illustrate our theoretical results are presented and discussed. Finally, we derive a threshold value for the females migration rate, when viruses are circulating, under which it is possible to lower the epidemiological risk in the treated area, according to the size of the human population.
Developing Wolbachia-based disease interventions for an extreme environment
23309P. A. Ross, S. Elfekih, S. Collier, M. J. Klein, S. S. Lee, M. Dunn, S. Jackson, Y. Zhang, J. K. Axford, X. Gu, M. S. Nasar, P. N. Paradkar, E. A. Taoufik, F. M. Jiggins, A. M. Almalik, M. B. Al-Fageeh and A. A. Hoffmann, bioRxiv, 2022.07.26.501527. 2022-07-27 07:59:12.
Aedes aegypti mosquitoes carrying self-spreading, virus-blocking Wolbachia bacteria are being deployed to suppress dengue transmission. However, there are challenges in applying this technology in extreme environments. We introduced two Wolbachia strains into Ae. aegypti from Saudi Arabia for a release program in the hot coastal city of Jeddah. Wolbachia reduced infection and dissemination of dengue virus (DENV2) in Saudi Arabian mosquitoes and showed complete maternal transmission and cytoplasmic incompatibility. Wolbachia reduced mosquito heat tolerance and egg viability, with the Wolbachia strains showing differential thermal stability. Wolbachia effects were similar across mosquito genetic backgrounds but we found evidence of local adaptation, with Saudi Arabian mosquitoes having lower egg viability but higher adult desiccation tolerance than Australian mosquitoes. Genetic background effects will influence Wolbachia invasion dynamics, reinforcing the need to use local genotypes for mosquito release programs, particularly in extreme environments like Jeddah. Our comprehensive characterization of Wolbachia strains provides a foundation for Wolbachia-based disease interventions in harsh climates.Competing Interest StatementThe authors have declared no competing interest.
Lack of robust evidence for a Wolbachia infection in Anopheles gambiae from Burkina Faso
23300S. P. Sawadogo, D. A. Kabore, E. B. Tibiri, A. Hughes, O. Gnankine, S. Quek, A. Diabaté, H. Ranson, G. L. Hughes and R. K. Dabiré, Medical and Veterinary Entomology, 2022-07-25 07:31:44.
The endosymbiont Wolbachia can have major effects on the reproductive fitness, and vectorial capacity of host insects and may provide new avenues to control mosquito-borne pathogens. Anopheles gambiae s.l is the major vector of malaria in Africa but the use of Wolbachia in this species has been limited by challenges in establishing stable transinfected lines and uncertainty around native infections. High frequencies of infection of Wolbachia have been previously reported in An. gambiae collected from the Valle du Kou region of Burkina Faso in 2011 and 2014. Here, we re-evaluated the occurrence of Wolbachia in natural samples, collected from Valle du Kou over a 12-year time span, and in addition, expanded sampling to other sites in Burkina Faso. Our results showed that, in contrast to earlier reports, Wolbachia is present at an extremely low prevalence in natural population of An. gambiae. From 5341 samples analysed, only 29 were positive for Wolbachia by nested PCR representing 0.54% of prevalence. No positive samples were found with regular PCR. Phylogenetic analysis of 16S rRNA gene amplicons clustered across supergroup B, with some having similarity to sequences previously found in Anopheles from Burkina Faso. However, we cannot discount the possibility that the amplicon positive samples we detected were due to environmental contamination or were false positives. Regardless, the lack of a prominent native infection in An. gambiae s.l. is encouraging for applications utilizing Wolbachia transinfected mosquitoes for malaria control.
Do Australians support genetic technology to control feral animals?
23095E. Phiddian, COSMOS, 2022-07-02 07:43:33.
Synthetic biology and genetic technology could be a safer, more humane way of curbing invasive species. Feral cat populations, for instance, could be controlled by preventing them from breeding. But there’s no point trying a new technology it if it doesn’t have public support – so does synthetic biology pass the pub test? According to a report from the CSIRO, it just might. Their survey of nearly 4,000 Australians finds that most support the idea of using gene drives on feral cats.“This particular study builds on our public acceptability work over the last three to four years on synthetic biology solutions to significant national challenges,” says Dr Aditi Mankad, co-author of the report and a researcher at CSIRO Land & Water’s Sustainability Pathways Program.
Partial masculinization of Aedes aegypti females by conditional expression of Nix
23113B. B. Kojin, E. Jakes, J. K. Biedler, Z. Tu and Z. N. Adelman, PLOS Neglected Tropical Diseases, 16:e0010598. 2022-07-01 08:17:41.
Here, we report on the conditional expression of Nixin transgenic A. aegypti under the control of the tetracycline-dependent (Tet-off) system, with the goal of establishing repressible sex distortion. A masculinization phenotype was observed in three of the seven transgenic lines with females exhibiting male-like long maxillary palps and most importantly, the masculinized females were unable to blood feed. Doxycycline treatment of the transgenic lines only partially restored the normal phenotype from the masculinized transgenic lines, while RT-qPCR analysis of early embryos or adults showed no correlation between the level of masculinization and ectopic Nix expression. While the conditional expression of Nix produced intersex phenotypes, the level of expression was insufficient to program full conversion. Modifications that increase both the level of activation (no tet) and the level of repression (with tet) will be necessary, as such this study represents one step forward in the development of genetic strategies to control vector-borne diseases via sex ratio distortion.
Public perspectives towards using gene drive for invasive species management in Australia
23100A. Mankad, E. V. Hobman and L. Carter, CSIRO, 2022-06-30 07:55:31.
Many pest animal species live and reproduce in high numbers across Australia. This includes animal species, such as cane toads, feral cats, foxes, rodents, wild pigs, wild rabbits. These species significantly damage Australia’s agricultural industries, natural landscapes, and biodiversity. For example, feral cats kill an estimated 1.8 billion Australian animals every year. Feral animals can also carry livestock diseases and cause significant damage to land and native vegetation. This results in agricultural production losses of more than $800 million per year. Sites of cultural significance to Indigenous peoples are also at risk to pest incursions. Adding further complexity, current methods of pest control being used to manage local landscape, such as baiting, trapping and shooting, are labour-intensive and expensive. They also have animal welfare implications and are considered ineffective at scale. Genetic technologies that are developed using synthetic biology have the potential to reduce or in some cases eliminate populations of invasive pests in parts of Australia. But there are multiple social, cultural and institutional considerations to understand before genetic technologies could feasibly be integrated with current pest management practices.
Breeding out the feral cat problem
23097S. Schmidt, ECOS, 2022-06-30 07:48:16.
While feral cats have only existed as part of Australia’s ecosystem for the last 200 or so years, they’ve left a destructive mark on our landscape. They’ve contributed to a growing list of Australian native animals that have become threatened or extinct in that time. Today, feral cats (Felis catus) are rampant in all parts of Australia, covering 99% of Australia’s total land area. That includes ecosystems from deserts to forests and grasslands, and even many of our offshore islands. Though they might share their species name and genome with their domestic counterparts, that’s where their similarity ends, explains Biosecurity Research Director at CSIRO, Dr Raghu Sathyamurthy. “Feral cats are opportunistic predators. They’re one of the most significant threats to our native species including small mammals, birds and reptiles,” says Dr Sathyamurthy.
The suppressive potential of a gene drive in populations of invasive social wasps is currently limited
23091A. B. Meiborg, N. R. Faber, B. A. Taylor, B. A. Harpur and G. Gorjanc, bioRxiv, 2022.06.27.497711. 2022-06-30 07:33:43.
Social insects are very successful invasive species, and the continued increase of global trade and transportation has exacerbated this problem. The yellow-legged hornet, Vespa velutina nigrithorax (henceforth Asian hornet), is drastically expanding its range in Western Europe. As an apex insect predator, this hornet poses a serious threat to the honey bee industry and endemic pollinators. Current suppression methods have proven too inefficient and expensive to limit its spread. Gene drives might be an effective tool to control this species, but their use has not yet been thoroughly investigated in social insects. Here, we built a model that matches the hornet’s life history and modelled the effect of different gene drive scenarios on an established invasive population. To test the broader applicability and sensitivity of the model, we also incorporated the invasive European paper wasp Polistes dominula. We find that although a gene drive can spread through a social wasp population, it can only do so under stringent gene drive-specific conditions. The main issue is that the large number of offspring that social wasp colonies produce guarantees that, even with very limited formation of resistance alleles, such alleles will quickly spread and rescue the population. Furthermore, we find that only a gene drive targeting female fertility is promising for population control due to the haplodiploidy of social insects. Nevertheless, continued improvements in gene drive technology may make it a promising method for the control of invasive social insects.Competing Interest StatementThe authors have declared no competing interest.
Australians open to using genetic technology to manage feral cats
23086CSIRO, MIRAGE, 2022-06-30 07:20:05.
New genetic technologies could help address the rise of invasives through a number of ways, one of which is called gene drive. Gene drive can determine the sex of offspring, reducing the number of animals able to reproduce, and therefore over time driving down populations. Researchers from CSIRO surveyed more than 3,800 people across Australia to understand public perceptions of using gene drive on feral cats. The research found 86 per cent of people were at least moderately supportive for the local implementation of gene drive technology to manage invasive feral cat species in their local area.
Manipulating Insect Sex Determination Pathways for Genetic Pest Management: Opportunities and Challenges
23084A. Siddall, T. Harvey-Samuel, T. Chapman and P. T. Leftwich, Frontiers in Bioengineering and Biotechnology, 10. 2022-06-28 07:14:08.
Sex determination pathways in insects are generally characterised by an upstream primary signal, which is highly variable across species, and that regulates the splicing of a suite of downstream but highly-conserved genes (transformer, doublesex and fruitless). In turn, these downstream genes then regulate the expression of sex-specific characteristics in males and females. Identification of sex determination pathways has and continues to be, a critical component of insect population suppression technologies. For example, “first-generation” transgenic technologies such as fsRIDL (Female-Specific Release of Insects carrying Dominant Lethals) enabled efficient selective removal of females from a target population as a significant improvement on the sterile insect technique (SIT). Second-generation technologies such as CRISPR/Cas9 homing gene drives and precision-guided SIT (pgSIT) have used gene editing technologies to manipulate sex determination genes in vivo. The development of future, third-generation control technologies, such as Y-linked drives, (female to male) sex-reversal, or X-shredding, will require additional knowledge of aspects of sexual development, including a deeper understanding of the nature of primary signals and dosage compensation. This review shows how knowledge of sex determination in target pest species is fundamental to all phases of the development of control technologies.
Intron-derived small RNAs for silencing viral RNAs in mosquito cells
23054P. Y. L. Tng, L. Z. Carabajal Paladino, M. A. E. Anderson, Z. N. Adelman, R. Fragkoudis, R. Noad and L. Alphey, PLOS Neglected Tropical Diseases, 16:e0010548. 2022-06-23 15:14:23.
Aedes aegypti and Ae. albopictus are the main vectors of mosquito-borne viruses of medical and veterinary significance. Many of these viruses have RNA genomes. Exogenously provided, e.g. transgene encoded, small RNAs could be used to inhibit virus replication, breaking the transmission cycle. We tested, in Ae. aegypti and Ae. albopictus cell lines, reporter based strategies for assessing the ability of two types of small RNAs to inhibit a chikungunya virus (CHIKV) derived target. Both types of small RNAs use a Drosophila melanogasterpremiRNA-1 based hairpin for their expression, either with perfect base-pairing in the stem region (shRNA-like) or containing two mismatches (miRNA-like). The pre-miRNA-1 stem loop structure was encoded within an intron; this allows co-expression of one or more proteins, e.g. a fluorescent protein marker tracking the temporal and spatial expression of the small RNAs in vivo. Three reporter-based systems were used to assess the relative silencing efficiency of ten shRNA-like siRNAs and corresponding miRNA-like designs. Two systems used a luciferase reporter RNA with CHIKV RNA inserted either in the coding sequence or within the 3’ UTR. A third reporter used a CHIKV derived split replication system. All three reporters demonstrated that while silencing could be achieved with both miRNA-like and shRNA-like designs, the latter were substantially more effective. Dcr-2 was required for the shRNA-like siRNAs as demonstrated by loss of inhibition of the reporters in Dcr-2 deficient cell lines. These positive results in cell culture are encouraging for the potential use of this pre-miRNA-1-based system in transgenic mosquitoes.
The AalNix3&4 isoform is required and sufficient to convert Aedes albopictus females into males
23070Y. Zhao, B. Jin, P. Liu, X. Xiao, L. Cai, Z. Xie, L. Kong, T. Liu, W. Yang, Y. Wu, J. Gu, Z. Tu, A. A. James and X.-G. Chen, PLOS Genetics, 18:e1010280. 2022-06-23 08:45:44.
Author summary Nix serves as a conserved male-determining factor in the two most important mosquito arboviral vectors, Ae. aegypti and Ae. albopictus. AaeNix alone can convert Ae. aegypti females into fertile but flightless males. AalNix has four alternative splice isoforms whereas AaeNix has one. Little was known previously about which AalNix isoform(s) serve as the primary signal for sex determination. We cloned the promoter region of AalNix gene and constructed piggybac-based AalNix overexpression constructs with different isoform variants. Following transformation and recovery of transgenic lines, we observed that expression of the AalNix3&4 isoform could shift the alternative splicing of the sex determination genes, doublesex and fruitless, from female to male isoforms, and phenotypically masculinize females or completely convert females into males. Importantly, the sex-converted pseudo-males are fertile and capable of flight. Thus, AalNix is the primary signal for male sex determination in Aedes albopictus and provides a basis for sex segregation and further Cas9-mediated gene-drive population suppression.
Sexual transmission of Anopheles gambiae densovirus (AgDNV) leads to disseminated infection in mated females
23030K. L. Werling, R. M. Johnson, H. C. Metz and J. L. Rasgon, Parasites and Vectors, 15:219. 2022-06-20 07:20:44.
Anopheles gambiae densovirus (AgDNV) is an insect-specific, single-stranded DNA virus that infects An. gambiae sensu stricto (s.s.), the major mosquito species responsible for transmitting malaria parasites throughout sub-Saharan Africa. AgDNV is a benign virus that is very specific to its mosquito host and therefore has the potential to serve as a vector control tool via paratransgenesis (genetic modification of mosquito symbionts) to limit transmission of human pathogens. Prior to being engineered into a control tool, the natural transmission dynamics of AgDNV between An. gambiae mosquitoes needs to be fully understood. Additionally, improved knowledge of AgDNV infection in male mosquitoes is needed. In the study presented here, we examined the tissue tropism of AgDNV in the male reproductive tract and investigated both venereal and vertical transmission dynamics of the virus.
Gene Editing and Genetic Control of Hemipteran Pests: Progress, Challenges and Perspectives
22757I. D. Pacheco, L. L. Walling and P. W. Atkinson, Frontiers in Bioengineering and Biotechnology, 10. 2022-06-07 08:02:11.
The origin of the order Hemiptera can be traced to the late Permian Period more than 230 MYA, well before the origin of flowering plants 100 MY later in during the Cretaceous period. Hemipteran species consume their liquid diets using a sucking proboscis; for phytophagous hemipterans their mouthparts (stylets) are elegant structures that enable voracious feeding from plant xylem or phloem. This adaptation has resulted in some hemipteran species becoming globally significant pests of agriculture resulting in significant annual crop losses. Due to the reliance on chemical insecticides for the control of insect pests in agricultural settings, many hemipteran pests have evolved resistance to insecticides resulting in an urgent need to develop new, species-specific and environmentally friendly methods of pest control. The rapid advances in CRISPR/Cas9 technologies in model insects such as Drosophila melanogaster, Tribolium castaneum, Bombyx mori, and Aedes aegypti has spurred a new round of innovative genetic control strategies in the Diptera and Lepidoptera and an increased interest in assessing genetic control technologies for the Hemiptera. Genetic control approaches in the Hemiptera have, to date, been largely overlooked due to the problems of introducing genetic material into the germline of these insects. The high frequency of CRISPR-mediated mutagenesis in model insect species suggest that, if the delivery problem for Hemiptera could be solved, then gene editing in the Hemiptera might be quickly achieved. Significant advances in CRISPR/Cas9 editing have been realized in nine species of Hemiptera over the past 4 years. Here we review progress in the Hemiptera and discuss the challenges and opportunities for extending contemporary genetic control strategies into species in this agriculturally important insect orderr.
Establishment of Wolbachia infection in Aedes aegypti from Pakistan via embryonic microinjection and semi-field evaluation of general fitness of resultant mosquito population
22856M. S. Sarwar, N. Jahan, A. Ali, H. K. Yousaf and I. Munzoor, Parasites and Vectors, 15:191. 2022-06-06 08:36:19.
BACKGROUND: Dengue is a mosquito-borne viral disease that is mainly spread by Aedes aegypti. It is prevalent on five continents, predominantly in tropical and sub-tropical zones across the world. Wolbachia bacteria have been extensively used in vector control strategies worldwide. The focus of the current study was to obtain a natural population of Ae. aegypti harbouring Wolbachia and to determine the impact of this bacteria on the new host in a semi-field environment. METHODS: Wolbachia-infected Aedes albopictus was collected from the city of Lahore, Punjab, Pakistan, and Wolbachia were successfully introduced into laboratory-reared Ae. aegypti via embryonic microinjection. The stable vertical transmission of wAlbB in the host population was observed for eight generations, and the impact of Wolbachia on the general fitness of the host was evaluated in semi-field conditions. RESULTS: In the laboratory and semi-field experiments, wAlbB Wolbachia presented a strong cytoplasmic incompatibility (CI) effect, evidenced as zero egg hatching, in crosses between Wolbachia-infected males and wild (uninfected) females of Ae. aegypti. Wolbachia infection had no noticeable impact on the general fitness (P > 0.05), fecundity, body size (females and males) and mating competitiveness of the new host, Ae. aegypti. However, there was a significant decrease in female fertility (egg hatch) (P < 0.001). In addition, under starvation conditions, there was a remarkable decrease (P < 0.0001) in the life span of Wolbachia-infected females compared to uninfected females (4 vs. > 5 days, respectively). CONCLUSIONS: Wolbachia strain wAlbB has a great potential to control the dengue vector in Ae. aegypti populations by producing 100% CI with a limited burden on its host in natural field conditions. This strain can be used as a biological tool against vector-borne diseases.
Modifying mosquitoes to suppress disease transmission: Is the long wait over?
22854J. R. Powell, Genetics, 2022-06-02 08:31:17.
For more than 50 years it has been a dream of medical entomologists and public health workers to control diseases like malaria and dengue fever by modifying, through genetics and other methods, the arthropods that transmit them to humans. A brief synopsis of the history of these efforts as applied to mosquitoes is presented; none proved to be effective in reducing disease prevalence. Only in the last few years have novel approaches been developed or proposed that indicate the long wait may be over. Three recent developments are particularly promising: CRISPR-Cas9 driven genetic modification, shifting naturally occurring allele frequencies, and microbe-based modifications. The last is the furthest along in implementation. Dengue fever incidence has been reduced between 40% and 96% in 4 different regions of the world where Wolbachia-infected Aedes aegypti have been established in the field. It is not yet clear how sustainable such control programs will prove to be, but there is good reason for optimism. In light of this, the time is ripe for reinvigorated research on vectors, especially genetics. Vector-borne diseases primarily affect under-developed countries and thus have not received the attention they deserve from wealthier countries with well-developed and funded biomedical research establishments.
Modeling the impact of genetically modified male mosquitoes in the spatial population dynamics of Aedes aegypti
23212M. R. da Silva, P. H. G. Lugão, F. Prezoto and G. Chapiro, Scientific Reports, 12:9112. 2022-06-01 06:29:36.
The mosquito Aedes aegypti is the primary vector of diseases such as dengue, Zika, chikungunya, and yellow fever. Improving control techniques requires a better understanding of the mosquito’s life cycle, including spatial population dynamics in endemic regions. One of the most promising techniques consists of introducing genetically modified male mosquitoes. Several models proposed to describe this technique present mathematical issues or rely on numerous parameters, making their application challenging to real-world situations. We propose a model describing the spatial population dynamics of the Aedes aegypti in the presence of genetically modified males. This model presents some mathematical improvements compared to the literature allowing deeper mathematical analysis. Moreover, this model relies on few parameters, which we show how to obtain or estimate from the literature. Through numerical simulations, we investigate the impacts of environmental heterogeneity, the periodicity of genetically modified male releases, and released genetically modified males quantity on the population dynamics of Aedes aegypti. The main results point to that the successful application of this vector control technique relies on releasing more than a critical amount of modified males with a frequency exceeding a specific critical value.
Wolbachia 16S rRNA haplotypes detected in wild Anopheles stephensi in eastern Ethiopia
22568E. Waymire, S. Duddu, S. Yared, D. Getachew, D. Dengela, S. R. Bordenstein, M. Balkew, S. Zohdy, S. R. Irish and T. E. Carter, Parasites and Vectors, 15:178. 2022-05-24 08:50:15.
About two out of three Ethiopians are at risk of malaria, a disease caused by the parasites Plasmodium falciparum and Plasmodium vivax. Anopheles stephensi, an invasive vector typically found in South Asia and the Middle East, was recently found to be distributed across eastern and central Ethiopia and is capable of transmitting both P. falciparum and P. vivax. The detection of this vector in the Horn of Africa (HOA) coupled with widespread insecticide resistance requires that new methods of vector control be investigated in order to control the spread of malaria. Wolbachia, a naturally occurring endosymbiotic bacterium of mosquitoes, has been identified as a potential vector control tool that can be explored for the control of malaria transmission. Wolbachia could be used to control the mosquito population through suppression or potentially decrease malaria transmission through population replacement. However, the presence of Wolbachia in wild An. stephensi in eastern Ethiopia is unknown. This study aimed to identify the presence and diversity of Wolbachia in An. stephensi across eastern Ethiopia.
Strategies to Mitigate Establishment under the Wolbachia Incompatible Insect Technique
23104S. Soh, S. H. Ho, J. Ong, A. Seah, B. S. Dickens, K. W. Tan, J. R. Koo, A. R. Cook, S. Sim, C. H. Tan, L. C. Ng and J. T. Lim, Viruses, 14. 2022-05-24 08:10:53.
The Incompatible Insect Technique (IIT) strategy involves the release of male mosquitoes infected with the bacterium Wolbachia. Regular releases of male Wolbachia-infected mosquitoes can lead to the suppression of mosquito populations, thereby reducing the risk of transmission of vector-borne diseases such as dengue. However, due to imperfect sex-sorting under IIT, fertile Wolbachia-infected female mosquitoes may potentially be unintentionally released into the environment, which may result in replacement and failure to suppress the mosquito populations. As such, mitigating Wolbachia establishment requires a combination of IIT with other strategies. We introduced a simple compartmental model to simulate ex-ante mosquito population dynamics subjected to a Wolbachia-IIT programme. In silico, we explored the risk of replacement, and strategies that could mitigate the establishment of the released Wolbachia strain in the mosquito population. Our results suggest that mitigation may be achieved through the application of a sterile insect technique. Our simulations indicate that these interventions do not override the intended wild type suppression of the IIT approach. These findings will inform policy makers of possible ways to mitigate the potential establishment of Wolbachia using the IIT population control strategy.
Novel molecular approaches to combat vectors and vector-borne viruses: Special focus on RNA interference (RNAi) mechanisms
22657A. Agarwal, D. K. Sarma, D. Chaurasia and H. S. Maan, Acta Tropica, 2022-05-24 06:45:12.
Vector-borne diseases, such as dengue, chikungunya, zika, yellow fever etc pose significant burden among the infectious diseases globally, especially in tropical and sub-tropical regions. Globalization, deforestation, urbanization, climate change, uncontrolled population growth, inadequate waste management and poor vector-management infrastructure have all contributed to the expansion of vector habitats and subsequent increase in vector-borne diseases throughout the world. Conventional vector control methods, such as use of insecticides, have significant negative environmental repercussions in addition to developing resistance in vectors. Till date, a very few vaccines or antiviral therapies have been approved for the treatment of vector borne diseases. In this review, we have discussed emerging molecular approaches like CRISPR (clustered regularly interspaced short palindromic repeats)/Cas-9, sterile insect technique (SIT), release of insects carrying a dominant lethal (RIDL), Wolbachia (virus transmission blocking) and RNA interference (RNAi) to combat vector and vector-borne viruses. Due to the extensive advancements in RNAi research, a special focus has been given on its types, biogenesis, mechanism of action, delivery and experimental studies evaluating their application as anti-mosquito and anti-viral agent. These technologies appear to be highly promising in terms of contributing to vector control and antiviral drug development, and hence can be used to reduce global vector and vector-borne disease burden.
Quality Control and Mating Performance of Irradiated Glossina palpalis gambiensis Males
22546K. Ilboudo, K. Camara, E. W. Salou and G. Gimonnea, Insects, 13. 2022-05-19 08:04:34.
The biological quality of sterile male insects produced in a mass-rearing facility is a prerequisite for the success of the SIT, which is a component of area-wide integrated pest management (AW-IPM). Indeed, sterile male insects released in the field must have a good mating performance in order to compete with wild males, but they must also present the required level of sterility. In the present study, the biological quality of sterile male Glossina palpalis gambiensis produced in a mass-rearing insectary was assessed through quality control testing. The mating performance of irradiated males was assessed in walk-in field cages. Irradiation had no effect on adult emergence but significantly reduced the percentage of operational flies (from 89.58% to 79.87%) and male survival (from 5 to 4 days, on average). However, irradiation did not impact the sterile male insemination potential, with all females inseminated and more than 80% of the spermathecae completely filled. The rate of induced sterility in females was 89.67% due to a dose rate decrease of the radiation source. Moreover, sterile males were able to compete successfully with untreated fertile males for untreated females in walk-in field cages. This study confirmed that the flies were still competitive and stressed the importance of regularly checking the radiation source parameters.
Aquatic invasive species specialists’ perceptions on the importance of genetic tools and concepts to inform management
22482T. A. Bernos, K. M. Jeffries and N. E. Mandrak, Biological Invasions, 24:1863-1879. 2022-05-14 07:09:36.
Perceptions related to the importance of genetic research influence the mobilization of genetic tools and concepts to inform conservation actions. Research characteristics, stakeholders’ perspectives, knowledge, and social linkages with geneticists influence the outcome of genetic information for management practices. We surveyed a broad range of aquatic invasive species (AIS) specialists whose opinions, perspectives, and decisions influence AIS decision-making. We assessed perceptions related to the importance of genetic tools and concepts, as well as the appropriateness of genetic biocontrol, and tested whether their expertise, background, and experience influenced perceptions in a predictable way. While perceptions towards genetic tools and concepts were generally heterogeneous, there was a high consensus (84%) related to the importance of eDNA. Most predictors were weakly correlated with importance ratings. Specialists’ genetic knowledge was the strongest predictor of higher importance ratings: the odds of AIS specialists giving higher ratings increased by up to 1.5-fold with increasing genetic knowledge. When evaluating the appropriateness of genetic biocontrol, level of support was lower for approaches based on gene editing (58%) than those relying on traditional hatchery techniques (70%). Support for gene editing varied by geographic location and with specialists’ knowledge of genetics and AIS management. These findings suggest that perceptions towards genetic research vary between genetic tools and concepts and are shaped by the interplay of individual’s values, expertise, experience, and background. To collaborate more effectively, genetic scientists must understand the extent of genetic knowledge of their AIS management partners and recognize that their conceptions of the conservation genetics research-practice space may vary.
Setting the world’s deadliest animal to self-destruct
22210A. Ossola, QUARTZ, 2022-05-08 15:29:34.
The mosquitoes are coming - and the, hopefully, they're going. This wee, British biotech company Oxitec plans to kick off a months-long experiment in which it will release billions of Aedes aegypti mosquitoes in California and Florida. But these aren't just any mosquitoes - they're genetically engineered so that they don't bite and will, if all goes according to plan, eventually reduce the population of mosquitoes in these areas.
Local adaptation of Aedes aegypti mosquitoes to Wolbachia-induced fitness costs
22208P. A. Ross and A. A. Hoffmann, bioRxiv, 2022.05.06.490959. 2022-05-06 15:19:41.
Aedes aegypti mosquito eggs can remain quiescent for many months before hatching, allowing populations to persist through unfavorable conditions. Aedes aegypti infected with the Wolbachia strain wMel have been released in tropical and subtropical regions for dengue control. wMel reduces the viability of quiescent eggs, but this physiological cost might be expected to evolve in natural mosquito populations that frequently experience stressful conditions. We therefore compared the costs of wMel infection for quiescent egg viability in field-derived and laboratory populations. Quiescent egg viability was highly variable in wMel-infected populations, with greater costs of wMel in field-derived populations. In contrast, there was little variation between matched field-derived and long-term laboratory populations lacking wMel, suggesting that laboratory adaptation does not influence this trait and that differences are due to wMel infection. Comparisons of populations collected a year apart show a decline in costs under laboratory rearing conditions involving a rapid turnover of mosquito generations; this pattern was consistent across populations despite their origin, suggesting adaptation of mosquitoes to the wMel infection under laboratory conditions. Reciprocal crossing experiments confirm that differences in quiescent egg viability were mainly due to the genetic background and not Wolbachia alone. wMel-infected mosquitoes hatching from long-term quiescent eggs showed partial loss of cytoplasmic incompatibility and female infertility, highlighting additional costs of long-term quiescence. Our study provides the first evidence for a shift in Wolbachia phenotypic effects following deliberate field release and establishment and it highlights interactions between Wolbachia infections and local adaptation. The unexpected changes in fitness costs observed here suggest potential tradeoffs with undescribed fitness benefits of the wMel infection.Competing Interest StatementThe authors have declared no competing interest.
The fight against malaria
22445F. Ammache, Year 2049, 2022-05-06 08:51:20.
Malaria is a disease we’ve been dealing with for thousands of years. Traces of the malaria parasite have been found in the remains of Egyptian mummies. Hippocrates described the fevers caused by malaria in Ancient Greece. The mosquito-filled Pontine Marshes protected Ancient Rome from invaders. Back then, we thought the disease was caused by people breathing “bad air”, or “mal aria”. The relationship between mosquitoes and malaria was unknown. Plasmodium falciparum, the deadliest form of malaria, was introduced by a new breed of mosquitoes around the 5th century. Some historians speculate that P. falciparum played a key role in the fall of the Roman Empire. It wasn’t until 1897 that we understood that mosquitoes transmitted malaria. Sir Ronald Ross, a British doctor based in India, found the malaria parasite in the blood of Anopheles mosquitoes which proved a hypothesis that was first put forward by his predecessor Alphonse Laveran.
Genetically Modified Mosquitoes May Protect The World From Disease
22213J. R. Learn, DISCOVER, 2022-05-04 15:29:48.
Forget lions, hippos or venomous spiders. Aedes aegypti mosquitoes may be among the deadliest wildlife in the world. Their bite is relatively harmless in normal circumstances. But many of these mosquitoes carry diseases they transmit from the blood of one host to another, including Zika, chikungunya, dengue and yellow fever. Like the related tiger mosquito that also carries these diseases, the Ae. aegypti are distinguished by black and white stripes along their legs. These mosquitoes thrive in urban areas, which makes the spread of the diseases they carry particularly insidious. They typically breed in small volumes of water, like in discarded tires and flower pots. But a new genetically engineered technology can get the mosquitoes to breed themselves out of existence. “We want to have a tool that’s going to have a real impact on disease transmission, and we want it to be accessible,” says Nathan Rose, head of regulatory affairs at Oxitec. “Our real focus has been on finding environmentally friendly ways of controlling pests.”
CRISPR/Cas9 mediates efficient site-specific mutagenesis of the odorant receptor co-receptor (Orco) in the malaria vector Anopheles sinensis
22554Y. Wang, X. F. He, L. Qiao, Z. R. Yu, B. Chen and Z. B. He, Pest Management Science, 11. 2022-04-28 14:52:27.
BACKGROUND Anopheles sinensis is the most widely distributed mosquito species and is the main transmitter of Plasmodium vivax malaria in China. Most previous research has focused on the mechanistic understanding of biological processes in An. sinensis and novel ways of interrupting malaria transmission. However, the development of functional genomics and genetics-based vector control strategies against An. sinensis remain limited because of insufficient site-specific genome editing tools. RESULTS We report the first successful application of the CRISPR/Cas9 mediated knock-in for highly efficient, site-specific mutagenesis in An. sinensis. The EGFP marker gene driven by the 3 x P3 promoter was precisely integrated into the odorant receptor co-receptor (Orco) by direct injections of Cas9 protein, double-stranded DNA donor, and Orco-gRNA. We achieved a mutation rate of 3.77%, similar to rates in other mosquito species. Precise knock-in at the intended locus was confirmed by polymerase chain reaction (PCR) amplification and sequencing. The Orco mutation severely impaired mosquito sensitivity to some odors and their ability to locate and discriminate a human host. CONCLUSION Orco was confirmed as a key mediator of multiple olfactory-driven behaviors in the An. sinensis life cycle, highlighting the importance of Orco as a key molecular target for malaria control. The results also demonstrated that CRISPR/Cas9 was a simple and highly efficient genome editing technique for An. sinensis and could be used to develop genetic control tools for this vector. (c) 2022 Society of Chemical Industry.
Biotechnological Road Map for Innovative Weed Management
22450A. C. S. Wong, K. Massel, Y. Lam, J. Hintzsche and B. S. Chauhan, Frontiers in Plant Science, 13. 2022-04-25 09:27:40.
In most agriculture farmlands, weed management is predominantly reliant on integrated weed management (IWM) strategies, such as herbicide application. However, the overuse and misuse of herbicides, coupled with the lack of novel active ingredients, has resulted in the uptrend of herbicide-resistant weeds globally. Moreover, weedy traits that contribute to weed seed bank persistence further exacerbate the challenges in weed management. Despite ongoing efforts in identifying and improving current weed management processes, the pressing need for novel control techniques in agricultural weed management should not be overlooked. The advent of CRISPR/Cas9 gene-editing systems, coupled with the recent advances in “omics” and cheaper sequencing technologies, has brought into focus the potential of managing weeds in farmlands through direct genetic control approaches, but could be achieved stably or transiently. These approaches encompass a range of technologies that could potentially manipulate expression of key genes in weeds to reduce its fitness and competitiveness, or, by altering the crop to improve its competitiveness or herbicide tolerance. The push for reducing or circumventing the use of chemicals in farmlands has provided an added incentive to develop practical and feasible molecular approaches for weed management, although there are significant technical, practical, and regulatory challenges for utilizing these prospective molecular technologies in weed management.
Role of CRISPR Technology in Gene Editing of Emerging and Re-emerging Vector Borne Disease
21811K. K. Mahto, P. Prasad, M. Kumar, H. Dubey and A. Ranjan, Recent Advances in Pathogen Interactions, Immunity, and Vector Control Strategies, 2022-04-23 05:49:18.
Vector borne diseases are rampant across the world. Due to spread and estab-lishment of vector species in different geographical areas, vector adaptation and resistance towards many insecticides the only option left is vector control for vari-ous vector borne diseases. Recent advancement in the field of genome editing have provided a variety of tools like, CRISPR, a novel genome editing techniques which can be applied for the control and prevention of many deadly diseases like dengue, chikungunya, filariasis, Japanese encephalitis and Zika. The present chapter is aimed to discuss the recent advancement in genome editing tools such as, their applica-tion, challenges, and limitations in vector control. Additionally, this chapter would potentially be advantageous to understand the hurdles, knowledge gaps in eliminating vector borne disease.
Trojan trout: could turning an invasive fish into a ‘super-male’ save a native species?
21823J. Miller, The Guardian, 2022-04-21 06:11:45.
Brook trout may greatly outnumber the Rio Grande cutthroat here, but nearly every brookie the team captures is male. That’s because many are a lab-produced variety known as “Trojan” brook trout. They are unique in that they carry not one, but two copies of the Y chromosome that codes maleness; they have no X chromosome to pass on. Since 2018, various streams across the Vermejo reserve have been stocked with this strain in an attempt to tilt the brook trout sex ratio so far male that eventually the population will stop breeding and die out on its own. Similar efforts are under way in a handful of creeks in Idaho, Washington and Oregon, and Nevada plans to embark on its own stocking programme this summer. Until now, the main tool to eliminate invasive fish species has been the potent chemical rotenone. The trouble is that “it also kills all the other fish, including the ones you are trying to conserve,” says Colleen Caldwell, a professor of fish and wildlife at New Mexico State University and a principal investigator overseeing the Leandro Creek project.
Genetically modified mosquitoes for controlling vector-borne diseases? Successful trial gives hope
21821T. Deol, Down To Earth, 2022-04-21 06:07:50.
Preliminary results of an open-air study of genetically engineered mosquitoes — with an aim to suppress a wild population of virus-carrying mosquitoes — in the United States have shown promising results. The aim of the experiment by Oxitec, a United Kingdom-based biotechnology firm, is to reduce the population of wild Aedes aegypti mosquitoes that is a vector for viruses such as chikungunya, dengue, zika and yellow fever. The scientists engineered a gene that will kill the female offspring. The results, achieved after a decade-long fight for public acceptance and regulatory approvals, are not enough. Larger studies are needed to understand whether the goal can be achieved or not. Their findings, yet to be published, were released during a webinar on 6 April. The experiment began in April 2021 in the Florida Keys but not without resistance from the residents. Their concerns ranged from the modified mosquitoes harming people, its impact on mosquito-eating species and other unintended consequences such as the emergence of a deadly virus.
Release of genetically modified mosquitoes created to fight disease a success: Biotech firm
21818C. Greenberg, National Post, 2022-04-20 06:03:19.
The release of genetically modified mosquitoes in the United States created to fight disease has gone according to plan, biotechnology firm Oxitec says.The first phase of the pilot study consisted of releasing almost 5 million modified Aedes aegypti male mosquitoes in the Florida Keys, a group of islands off the southern tip of Florida, in April 2021. The results indicated that the method may eventually succeed in eradicating or downsizing the number of Aedes aegypti mosquitoes. Aedes aegypti only make up 4 per cent of the mosquito population in the Keys, but are responsible for spreading yellow fever, dengue, chikungunya and Zika virus, Oxitec said during an online seminar revealing their findings on April 6. “The mosquito is very difficult to control. It likes to live around people, in houses, under houses,” said Andrea Leal, executive director of the Florida Keys Mosquito Control District. “We’re also seeing an increase in resistance to a number of our adulticide products that we use for mosquito control, so at the end of it, we’re looking for new tools to put in our toolbox to help us control this particular mosquito.”
Tests of Genetically Modified Mosquitoes Prove Positive
21816R. Ellis, WebMD, 2022-04-20 05:59:18.
The first open-air study of genetically modified mosquitoes in the United States has yielded positive results, says Oxitec, the UK-based company that ran the study. However, Oxitec says larger tests are needed to determine whether the insects can suppress the disease-spreading mosquito population in the wild, according to Nature. Dengue, Zika, and yellow fever are some of the diseases the experiments hope to reduce. Scientists at Oxitec mass produced and genetically modified male Aedes aegypti mosquito eggs in a lab. The males were released into the wild to mate with females and pass along a gene designed to kill the female offspring, which are the only ones that bite and spread the diseases. The male offspring live on.
Genetically Modified Mosquitoes Work as Intended
21814M. L. Ford, NEWSER, 2022-04-19 05:54:33.
Results are in from a pilot study in Florida, where millions of genetically engineered mosquitoes were released into the wild. Some referred to it as the “Jurassic Park” experiment when it was announced last year, but—so far—everything is going to plan, according to UK biotech firm Oxitec. Per Nature, the experiment is part of a long-term plan to develop new tools in the fight against the invasive Aedes aegypti mosquito, which can carry dengue, Zika, and other gnarly viruses. Genetically modified male mosquitoes were released into the wild to mate with the local females; as hoped, affected female offspring died before reaching adulthood, and male offspring carried the engineered gene. By the way, the engineered males and their offspring do not bite humans. Ultimately, the hope is to suppress if not eradicate A. aegypti; however, this phase was focused on ensuring that the method works. In addition to preventing reproduction, the gene was successfully passed to succeeding generations of males for three months, and then it disappeared from the local population. Oxitec’s work is EPA-approved, and it works closely with state wildlife agencies. Similar experiments will soon begin in California. “I like the way they’re going about it,” Thomas Scott, an entomologist at UC-Davis, told Nature. “They’re doing it in a systematic, thoughtful way. So I’m encouraged.”
The sterile insect technique is protected from evolution of mate discrimination
21768J. J. Bull and R. Gomulkiewicz, PeerJ, 10:e13301. 2022-04-18 07:53:47.
Background The sterile insect technique (SIT) has been used to suppress and even extinguish pest insect populations. The method involves releasing artificially reared insects (usually males) that, when mating with wild individuals, sterilize the broods. If administered on a large enough scale, the sterility can collapse the population. Precedents from other forms of population suppression, especially chemicals, raise the possibility of resistance evolving against the SIT. Here, we consider resistance in the form of evolution of female discrimination to avoid mating with sterile males. Is resistance evolution expected? Methods We offer mathematical models to consider the dynamics of this process. Most of our models assume a constant-release protocol, in which the same density of males is released every generation, regardless of wild male density. A few models instead assume proportional release, in which sterile releases are adjusted to be a constant proportion of wild males. Results We generally find that the evolution of female discrimination, although favored by selection, will often be too slow to halt population collapse when a constant-release implementation of the SIT is applied appropriately and continually. The accelerating efficacy of sterile males in dominating matings as the population collapses works equally against discriminating females as against non-discriminating females, and rare genes for discrimination are too slow to ascend to prevent the loss of females that discriminate. Even when migration from source populations sustains the treated population, continued application of the SIT can prevent evolution of discrimination. However, periodic premature cessation of the SIT does allow discrimination to evolve. Likewise, use of a ‘proportional-release’ protocol is also prone to escape from extinction if discriminating genotypes exist in the population, even if those genotypes are initially rare. Overall, the SIT is robust against the evolution of mate discrimination provided care is taken to avoid some basic pitfalls. The models here provide insight for designing programs to avoid those pitfalls.
The plan to release genetically engineered mosquitoes in California
21703M. Petersen, Phys Org, 2022-04-12 08:50:04.
In the mosquito breeding rooms of British biotech company Oxitec, scientists line up fresh eggs, each the size of a grain of salt. Using microscopic needles, the white-coated researchers inject each egg with a dab of a proprietary synthetic DNA. For four days, Oxitec technicians care for the eggs, watching for those that hatch into wriggling brown larvae. Those "injection survivors," as the company calls them, face a battery of tests to ensure their genetic modification is successful. Soon, millions of these engineered mosquitoes could be set loose in California in an experiment recently approved by the federal government. Oxitec, a private company, says its genetically modified bugs could help save half the world's population from the invasive Aedes aegypti mosquito, which can spread diseases such as yellow fever, chikungunya and dengue to humans. Female offspring produced by these modified insects will die, according to Oxitec's plan, causing the population to collapse. "Precise. Environmentally sustainable. Non-toxic," the company says on its website of its product trademarked as the "Friendly" mosquito.
Genetically-Modified Mosquitos Could Soon Be Released in California
21693A. Madrigal, KQED, 2022-04-12 08:31:27.
Millions of genetically-modified, non-biting mosquitoes may soon be set loose in California after federal regulators gave the green light to a study aimed at preventing transmission of diseases like Zika and dengue. British biotech firm Oxitech says its technology alters male mosquitos to only produce viable male offspring, leading to population declines as females die off. While it may sound like the plot of a horror movie, the company says the new process is safe and necessary to address the growing global threat of mosquito-borne diseases. But some scientists and other critics say it could create even more virulent mosquitos, among other health and environmental risks. We’ll discuss the plan, which still requires state approval.
Genetically Modified Mosquitoes May Be Released in California, Experts Express Concern
21719Z. Papadakis, NEWSMAX, 2022-04-11 09:25:49.
Millions of genetically engineered mosquitos could soon be set loose in California in an effort to curb the disease-carrying Aedes aegypti mosquito population — but some experts are concerned that it could backfire. On March 7, Oxitec, a private company, obtained a permit from the U.S. Environmental Protection Agency to release its mosquitos in specific districts in Florida and California. The company reasoned that its genetically modified insects could help to save the world half of the world's population from the invasive Aedes aegypti mosquito which, according to Oxitec, increases the risk of transmission of dengue, chikungunya, Zika, yellow fever, and other diseases. "Given the growing health threat this mosquito poses across the U.S., we're working to make this technology available and accessible," Grey Frandsen, CEO of Oxitec, said in a statement. "These pilot programs, wherein we can demonstrate the technology's effectiveness in different climate settings, will play an important role in doing so. We look forward to getting to work this year."
Will genetic modification of mosquitoes take a bite out of insects’ population?
21708N. Patel, KCRW, 2022-04-11 08:58:40.
An invasive species of aggressive “ankle biters” called the Aedes aegypti mosquito is now in LA, and it’s spreading quickly. These tiny vampires can lay eggs in a space as small as a water-filled bottle cap, and they carry diseases like yellow fever and dengue. A British company called Oxitec is now trying to eradicate them through genetic modification. Oxitec will release millions of modified mosquitoes that can only produce female offspring that will die. Without an ability to reproduce, the mosquito population will collapse. The Environmental Protection Agency (EPA) granted the company a permit to release their modified mosquitoes in San Bernardino, Fresno, Stanislaus, and Tulare Counties.
An army of genetically engineered mosquitoes is about to be released
21705M. Menard, KNX NEWS, 2022-04-11 08:53:53.
A British biotech company has been altering the DNA of mosquitoes with the goal of killing off a more dangerous breed capable of spreading deadly diseases. And now they’re preparing to release their “friendly mosquitoes” into the wild. In California. Aedes aegypti is an invasive breed of mosquito that has been rapidly spreading throughout the state since their first detection about 10 years ago. It is a known carrier of such diseases as yellow fever, chikungunya and dengue.
California’s first genetically modified mosquitoes may soon be released
21698A. M. Asperin, FOX11 Los Angeles, 2022-04-10 08:41:01.
How would you feel about a few genetically engineered mosquitoes flying into your neighborhood? It's a possibility after the US Environmental Protection Agency on Friday approved pilot projects of Oxitec's mosquitoes in specific districts in California and Florida. The next step is for applications to be submitted to state regulators, who must approve the project for it to move forward.
In California, an army of genetically engineered mosquitoes awaits release. Will it backfire?
21652M. Petersen, Los Angeles Times, 2022-04-08 15:00:55.
In the mosquito breeding rooms of British biotech company Oxitec, scientists line up fresh eggs, each the size of a grain of salt. Using microscopic needles, the white-coated researchers inject each egg with a dab of a proprietary synthetic DNA. For four days, Oxitec technicians care for the eggs, watching for those that hatch into wriggling brown larvae. Those “injection survivors,” as the company calls them, face a battery of tests to ensure their genetic modification is successful. Soon, millions of these engineered mosquitoes could be set loose in California in an experiment recently approved by the federal government. Oxitec, a private company, says its genetically modified bugs could help save half the world’s population from the invasive Aedes aegypti mosquito, which can spread diseases such as yellow fever, chikungunya and dengue to humans. Female offspring produced by these modified insects will die, according to Oxitec’s plan, causing the population to collapse.
Federal Government Approves Release of Millions of Genetically Engineered Mosquitoes in California
21681A. Jose, The Western Journal, 2022-04-08 08:10:32.
Genetically modified Aedes aegypti mosquitoes could soon buzz around in California and Florida after the federal government greenlighted a plan to release the insects in the states. The project is spearheaded by biotechnology firm Oxitec, which, among other things, specializes in biological pest control solutions. “Oxitec’s Friendly™ safe, non-biting male mosquitoes are designed to suppress local wild populations of disease-spreading mosquitoes,” Oxitec’s website states. According to the company, the genetically modified mosquitoes have a “self-limiting gene,” which ensures that when the “Friendly™ mosquito males mate with wild females, their offspring inherit a copy of this gene.” The gene stops female offspring from maturing into adulthood, culling their reproducibility. However, male offspring carrying the gene will survive and pass those on to their offspring, the company said.
Billions of Genetically Modified Mosquitoes Are Set to Descend on California and Florida This Summer
21658J. Rossen, MENTAL FLOSS, 2022-04-06 15:11:44.
Californians may not know it on sight, but there’s going to be something different about their mosquitoes this summer. An invasive species of the bite-prone insects has been genetically modified in an attempt at controlling disease spread. According to Smithsonian, the Environmental Protection Agency (EPA) has approved plans by biotech firm Oxitec to release 2.4 billion male Aedes aegypti mosquitos in both California and Florida that have been altered so their genes can only participate in producing surviving male offspring. (Females will die before reaching adulthood.) The insects will be introduced as eggs, which will then hatch when exposed to water. Because male mosquitoes do not bite, the theory is that a declining female mosquito population will reduce transmission of Zika, yellow fever, dengue, and other infectious diseases that can be passed on to humans from the bites. The goal is halting outbreaks before they begin. In 2021, Oxitec released 144,000 genetically modified mosquitoes in the Florida Keys. The insects have also been introduced in Brazil, the Cayman Islands, Panama, and India. While there is no spread of such diseases in California, the firm says a growing mosquito population could eventually pose a problem and that such pilot programs are necessary to assess effectiveness
Podcast: How do you solve a problem like malaria?
21655A. Jha, The Economist, 2022-04-05 15:01:14.
SQUASHING MALARIA could, over the next three decades, save as many lives as covid-19 has taken. We explore new ways to fight infections: from the introduction of the first malaria vaccines, to genetically modified mosquitoes
Genetically modified mosquitoes, a potential antidote to deadly diseases
21634TRTWorld, TRTWorld, 2022-04-01 08:08:35.
The US approved the release of billions of genetically modified mosquitoes to reduce the transmission of diseases but critics point to possible unintended consequences. Can genetically modified animals combat the spread of deadly diseases? The United States Environmental Protection Agency (EFA) thinks so. The agency has approved the release of over 2 billion mosquitoes that were genetically altered specifically to reduce the transmission of deadly transmissible diseases such as Zika, chikungunya, dengue, and yellow fever.The program in Florida and California will be put into action by the British biotechnology company Oxitec that genetically modify the mosquitos, mainly male Aedes aegypti eggs, in a lab. The mosquitos then will mate with females, only to pass the modified gene that would kill the female offspring. As a result, only the male offspring will stay alive as only the female ones spread the disease. The project also needs the approval of both states’ regulators and will be carried out in partnership with the Delta Mosquito and Vector Control district in Tulare county.
Overview of paratransgenesis as a strategy to control pathogen transmission by insect vectors
21579N. A. Ratcliffe, J. P. Furtado Pacheco, P. Dyson, H. C. Castro, M. S. Gonzalez, P. Azambuja and C. B. Mello, Parasites and Vectors, 15:112. 2022-03-31 12:47:27.
This article presents an overview of paratransgenesis as a strategy to control pathogen transmission by insect vectors. It first briefly summarises some of the disease-causing pathogens vectored by insects and emphasises the need for innovative control methods to counter the threat of resistance by both the vector insect to pesticides and the pathogens to therapeutic drugs. Subsequently, the state of art of paratransgenesis is described, which is a particularly ingenious method currently under development in many important vector insects that could provide an additional powerful tool for use in integrated pest control programmes. The requirements and recent advances of the paratransgenesis technique are detailed and an overview is given of the microorganisms selected for genetic modification, the effector molecules to be expressed and the environmental spread of the transgenic bacteria into wild insect populations. The results of experimental models of paratransgenesis developed with triatomines, mosquitoes, sandflies and tsetse flies are analysed. Finally, the regulatory and safety rules to be satisfied for the successful environmental release of the genetically engineered organisms produced in paratransgenesis are considered.
Comparison of Ground Release and Drone-Mediated Aerial Release of Aedes aegypti Sterile Males in Southern Mexico: Efficacy and Challenges
21574C. F. Marina, P. Liedo, J. G. Bond, A. R. Osorio, J. Valle, R. Angulo-Kladt, Y. Gómez-Simuta, I. Fernández-Salas, A. Dor and T. Williams, Insects, 13. 2022-03-31 12:43:15.
Sterile males of Aedes aegypti were released once a week for 8 weeks to evaluate the dispersal efficiency of ground and aerial drone release methods in a rural village of 26 Ha in southern Mexico. Indoor and outdoor BG-Sentinel traps were placed in 13–16 houses distributed throughout the village. The BG traps were activated 48 h after the release of the sterile males and functioned for a 24 h period following each release. Over the 8-week period of simultaneous ground and aerial releases, an average of 85,117 ± 6457 sterile males/week were released at ground level and 86,724 ± 6474 sterile males/week were released using an aerial drone. The ground release method resulted in higher numbers of captured males (mean = 5.1 ± 1.4, range 1.1–15.7 sterile males/trap) compared with the aerial release method (mean = 2.6 ± 0.8, range 0.5–7.3 sterile males/trap) (p < 0.05). Similarly, the prevalence of traps that captured at least one sterile male was significantly higher for ground release compared to the aerial release method (p < 0.01). The lower numbers of sterile males captured in the aerial release method could be due to mortality or physical injury caused by the chilling process for immobilization, or the compaction of these insects during transport and release. However, aerial releases by a two-person team distributed insects over the entire village in just 20 min, compared to ~90 min of work for a five-person team during the ground release method. Ground release also resulted in higher aggregations of males and some villagers reported feeling discomfort from the presence of large numbers of mosquitoes in and around their houses. We conclude that modifications to the handling and transport of sterile males and the design of containers used to store males are required to avoid injury and to improve the efficiency of aerial releases for area-wide SIT-based population suppression programs targeted at mosquito vectors of human disease.
Why a U.S. Company Plans to Release 2.4 Billion Genetically Modified Mosquitoes
21569M. Osborne, Smithosonian Magazine, 2022-03-30 12:35:35.
The Environmental Protection Agency has cleared the release of 2.4 billion genetically-modified mosquitoes in California and Florida. The mosquitoes, created by biotech firm Oxitec, will be non-biting Aedes aegypti males engineered to only produce viable male offspring, per the company. Oxitec says the plan will reduce numbers of the invasive Aedes aegypti, which can carry diseases like Zika, yellow fever and dengue. Female mosquitoes will die, while males will reproduce and spread the self-limiting gene to the next generation, eventually leading to population declines. While these diseases aren’t yet spreading in California, the invasive insect has been flagged as a growing risk as their numbers increase across the state, reports the Guardian’s Gabrielle Canon. “Given the growing health threat this mosquito poses across the U.S., we’re working to make this technology available and accessible,” Oxitec CEO Grey Frandsen says in a statement. “These pilot programs, wherein we can demonstrate the technology’s effectiveness in different climate settings, will play an important role in doing so.”
Cytoplasmic incompatibility: A Wolbachia toxin–antidote mechanism comes into view
21546M. Hochstrasser, Current Biology, 32:R287-R289. 2022-03-28 11:56:01.
The Wolbachia cidA and cidB genes promote bacterial endosymbiont inheritance through the host female germline. CidB is now shown to load into maturing sperm nuclei. Following fertilization, it disrupts paternal chromosome condensation, triggering embryonic arrest if not countered by CidA in Wolbachia-infected eggs.
US poised to release 2.4bn genetically modified male mosquitoes to battle deadly diseases
21571G. Canon, The Guardian, 2022-03-26 12:38:38.
Genetically modified male mosquitoes may soon be buzzing across areas of California, in an experiment to stop the spread of invasive species in a warming climate. Earlier this month, the EPA cleared the UK-based biotech company Oxitec to release a maximum of roughly 2.4bn of its genetically modified mosquitoes through 2024, expand its existing trial in Florida and start a new pilot project in California’s Central Valley, where mosquito numbers are on the rise. Oxitec’s modified mosquitoes are male, and therefore don’t bite. They were developed with a special protein so that when they pair with a female mosquito the only viable offspring they produce are also non-biting males. The project specifically targets the Aedes aegypti mosquito, one of more than 3,500 mosquito species and a dangerous invasive insect that has spread diseases like dengue, Zika, Chikungunya, and yellow fever in other countries.
Millions of genetically engineered mosquitoes are here to protect us
21551M. Kaufman, MASHABLE, 2022-03-26 12:06:29.
Aedes aegypti almost certainly traveled to California in cargo, like many invasive species do. The species, which flourishes in warmer climes, has colonized places like Los Angeles County, and is expected to multiply and spread in these temperate regions as the climate continuously warms. The invasive species has already thrived in the Gulf states for centuries. Crucially, Aedes aegypti aren't simply an itchy annoyance (the females voraciously bite for blood meals): The mosquitoes spread viral diseases like dengue fever, yellow fever, Zika, among others. Future outbreaks in new and old parts of the U.S. have a realistic, unsettling potential. To prepare, the U.S. Environmental Protection Agency recently allowed for the carefully regulated, experimental release of over 2.4 million genetically-modified mosquitoes in California and Florida over the next couple of years. It's a pilot project intended to prove that Aedes aegypti populations can be repressed by genetically-altered mosquitoes. The modified mosquitoes are non-biting males carrying a manipulated gene that, after mating, kills the insects' offspring. The biotechnology company Oxitec devised this mosquito-control strategy, and will run the tests.
Field Suppression of Spotted Wing Drosophila (SWD) (Drosophila suzukii Matsumura) Using the Sterile Insect Technique (SIT)
21241R. A. Homem, Z. Mateos-Fierro, R. Jones, D. Gilbert, A. R. McKemey, G. Slade and M. T. Fountain, Insects, 13. 2022-03-26 06:14:15.
Drosophila suzukii (spotted wing drosophila—SWD) is an economically important pest of soft and stone fruit worldwide. Control relies on broad-spectrum insecticides, which are neither fully effective nor environmentally sustainable. The sterile insect technique (SIT) is a proven, effective and environmentally friendly pest-management tool. Here, we investigated, for the first time, the potential of using SIT to control D. suzukii in field conditions without physical barriers that limit insect invasion. A proprietary method of rearing and irradiation with X-rays was used to obtain males that were 99% sterile. Sterile males were released twice per week from April to October 2021 on a site in Kent, UK, where everbearing strawberries were grown in open polytunnels. The infestation of wild female D. suzukii was monitored weekly using red sticky traps with dry lure at the treated site and at two similar control sites that did not receive sterile male releases. Releases of sterile males suppressed the wild female D. suzukii population by up to 91% in comparison with the control sites. We thus demonstrated the feasibility of SIT to achieve season-long control of D. suzukii using early, sustained and dynamically targeted releases of sterile males. This provides a promising environmentally friendly method to control this important pest.
Special mosquitos to combat dengue fever in Binh Duong
21249L. Phuong, VN Express, 2022-03-25 08:39:12.
Capsules containing mosquito eggs resistant to dengue fever viruses were released in southern Binh Duong's Thu Dau Mot Town on Thursday to help control the disease. The Wolbachia Project in southern Vietnam, conducted by the World Mosquito Program and collaborators, seeks to release mosquitos infected with the Wolbachia bacteria into the environment. The bacteria, a natural pathogen to several insects, would compete with viruses like dengue, Zika, chikungunya and yellow fever found inside mosquitos, thus making it harder for viruses to replicate and for mosquitos to spread the viruses to humans.
A scourge of genetically modified mosquitoes could be unleashed in California
21236J. Bote, SFGATE, 2022-03-21 05:16:37.
A genetically modified scourge of mosquitoes could be unleashed throughout California as municipalities across the state grapple with increasing bouts of an invasive mosquito species. The mosquitoes, developed by the British biotech firm Oxitec, are known as OX5034 — a modified male version of Aedes aegypti, the species that first emerged in Los Angeles County about a decade ago before spreading to at least 22 different counties across the state. They are an invasive species known to carry dengue, Zika and a host of other diseases, and naturally spread in contained, urban spaces with standing water, such as flowerpots and open water bottles. Up to 2 million OX5034 mosquitoes could be released in the coming years throughout the state, pending state approval by the California Department of Pesticide Regulation. The male species, which naturally do not bite humans, carry a gene that will ensure that female offspring do not grow into childhood. Male offspring, however, will survive — and continue to pass down the gene to further generations, hopefully eradicating the invasive species for good.
Symbionts and gene drive: two strategies to combat vector-borne disease
21029G.-H. Wang, J. Du, C. Y. Chu, M. Madhav, G. L. Hughes and J. Champer, Trends in Genetics, 2022-03-18 07:56:11.
Mosquitoes bring global health problems by transmitting parasites and viruses such as malaria and dengue. Unfortunately, current insecticide-based control strategies are only moderately effective because of high cost and resistance. Thus, scalable, sustainable, and cost-effective strategies are needed for mosquito-borne disease control. Symbiont-based and genome engineering-based approaches provide new tools that show promise for meeting these criteria, enabling modification or suppression approaches. Symbiotic bacteria like Wolbachia are maternally inherited and manipulate mosquito host reproduction to enhance their vertical transmission. Genome engineering-based gene drive methods, in which mosquitoes are genetically altered to spread drive alleles throughout wild populations, are also proving to be a potentially powerful approach in the laboratory. Here, we review the latest developments in both symbionts and gene drive-based methods. We describe some notable similarities, as well as distinctions and obstacles, relating to these promising technologies.
Differential viral RNA methylation contributes to pathogen blocking in Wolbachia-colonized arthropods
20977T. Bhattacharya, L. Yan, J. M. Crawford, H. Zaher, I. L. G. Newton and R. W. Hardy, PLoS Pathogens, 18:e1010393. 2022-03-16 07:40:04.
Arthropod endosymbiont Wolbachia pipientis is part of a global biocontrol strategy to reduce the replication of mosquito-borne RNA viruses such as alphaviruses. We previously demonstrated the importance of a host cytosine methyltransferase, DNMT2, in Drosophila and viral RNA as a cellular target during pathogen-blocking. Here we report a role for DNMT2 in Wolbachia-induced alphavirus inhibition in Aedes species. Expression of DNMT2 in mosquito tissues, including the salivary glands, is elevated upon virus infection. Notably, this is suppressed in Wolbachia-colonized animals, coincident with reduced virus replication and decreased infectivity of progeny virus. Ectopic expression of DNMT2 in cultured Aedes cells is proviral, increasing progeny virus infectivity, and this effect of DNMT2 on virus replication and infectivity is dependent on its methyltransferase activity. Finally, examining the effects of Wolbachia on modifications of viral RNA by LC-MS show a decrease in the amount of 5-methylcytosine modification consistent with the down-regulation of DNMT2 in Wolbachia colonized mosquito cells and animals. Collectively, our findings support the conclusion that disruption of 5-methylcytosine modification of viral RNA is a vital mechanism operative in pathogen blocking. These data also emphasize the essential role of epitranscriptomic modifications in regulating fundamental alphavirus replication and transmission processes.
Billions of GE Mosquitoes May Soon Be Released in California and Florida
21009A. N. Mitra, Earth Island Journal, 2022-03-16 06:18:31.
he US Environmental Protection Agency’s decision last week to allow the release of billions of genetically engineered mosquitoes in California and Florida has several environmental and public health groups worried about the potential impacts of the experimental releases on public health and the environment. The EPA move follows last year’s pilot field trial in the Florida Keys where, starting April 2021, the British biotechnology company Oxitec and the Florida Keys Mosquito Control released half a billion of these transgenic mosquitoes. The purpose was to test if they could help reduce populations of Aedes aegypti, a mosquito species that can carry viruses that cause deadly diseases like yellow fever, dengue, chikungunya, and Zika — none of which are major concerns in the United States.
California’s first lab-grown mosquitoes may take flight—stirring controversy
21022L. M. Krieger, Phys Org, 2022-03-15 06:51:22.
A biotech firm is seeking permission to release genetically modified mosquitoes into the open air of California for the first time later this year, aiming to reduce the expanding populations of invasive mosquitoes and prevent deadly disease. The controversial research project—planned for the Tulare County community of Visalia, with potential expansion into Fresno, San Bernadino and Stanislaus counties—will over time introduce 2 million male mosquitoes with a "kill switch" built into their DNA. When they mate with wild insects, their offspring die, causing an eventual collapse of the population. Their target: Swarms of the mosquito, first detected in Los Angeles County in 2011, which have since spread northward into 20 California counties. While California's native mosquito emerges at dusk, these black-and-white-striped invaders hunt for blood during the day, when people are outside. Elsewhere, they transmit potentially fatal Zika, dengue, yellow fever, chikungunya and other viruses.
Fall armyworms with offspring-killing gene tested on farms in Brazil
21020M. Le Page, New Scientist, 2022-03-15 06:46:51.
Fall armyworms genetically modified to wipe out wild populations of the pests have been released in corn fields in São Paulo State in Brazil in the first farm trial of the new technology. The test was a success and is now being expanded, says Oxitec, the UK-based company that created the modified armyworms. Fall armyworms (Spodoptera frugiperda) are in fact moth caterpillars. They get their name from the fact that they multiply very fast and feed on many plants. Swarms of armyworms can devastate everything from lawns to crops in just days. They are native to the Americas, but in recent years have spread across Africa, Asia and Australia, reducing harvests of some crops by up to half. Conventional control methods aren’t working well because some strains have evolved resistance to many pesticides. “There is a lot of interest in new solutions to this pest,” says Neil Morrison at Oxitec. “Growers are struggling to control it through insecticidal means.” For its method of control, Oxitec took a strain of fall armyworm that is still susceptible to pesticides and modified males so that their female offspring can survive only in the presence of a specific chemical. In other words, the males carry a gene that kills all their female offspring in the wild.
Genetically modified mosquitoes kill their own offspring
21024C. Ward, SYFY, 2022-03-14 06:55:40.
Oxitec, a biotech company, has developed a strain of A. aegypti which they call Friendly. Their modified mosquitos are all males and carry a gene which prevents the birth of females in subsequent generations. In short, they’re reducing disease-carrying mosquitos by killing their babies before they hatch. The Environmental Protection Agency has granted permission for the release of the experimentally modified mosquitos in Florida, and those same mosquitos may soon be released in California. While the federal government has agreed to the program, permission must also be obtained from the states where the releases will occur before they can proceed. Should California grant permission, populations of modified mosquitos could be released in Stanislaus, Fresno, Tulare, and San Bernadino counties soon. Once released, modified male mosquitos breed with wild females, delivering the desired gene sequence to the next generation. Any females in the next generation are terminated before being born and all males which are produced carry the same gene, allowing them to continue the cycle through several generations. Oxitec considers the modification inherently self-limiting and estimates that it will vanish from the overall population after a few generations, at which point mosquito populations will return to normal reproduction.
Combining two Genetic Sexing Strains allows sorting of non-transgenic males for Aedes genetic control
20642C. Lutrat, M. Burckbuchler, R. P. Olmo, R. Beugnon, A. Fontaine, T. Baldet, J. Bouyer and E. Marois, bioRxiv, 2022.03.11.483912. 2022-03-12 08:15:59.
Chemical control of the mosquito vectors Aedes albopictus and Aedes aegypti is costly, unsustainable, and increasingly ineffective due to the spread of insecticide resistance. The Sterile Insect Technique is an autocidal control tactic that represents a valuable alternative but is limited by the slow, error-prone, and wasteful sex-separation stage. Here, we present four genetic sexing strains (two for each Aedes species) based on fluorescence markers linked to the m and M sex loci, allowing the isolation of transgenic males. Furthermore, we show how combining these sexing strains allows the production of non-transgenic males. Scaling-up would allow the sorting of 100,000 neonate male larvae in under 1.5 hour with 0.01-0.1% female contamination. The resulting males present similar survival and flight ability to laboratory-reared wild-type males. By facilitating the sorting of transgenic or non-transgenic males, these Genetic Sexing Strains should enable a major upscaling in control programmes against these major vectors.Competing Interest StatementThe authors have declared no competing interest.
Millions Of Genetically Modified Mosquitoes To Be Set Loose In US
20638H. Wilmerding, Daily Caller, 2022-03-11 08:11:40.
Millions of genetically modified mosquitoes will be released in the United States as part of an initiative to replace the insects carrying deadly diseases, the company behind the plan announced Tuesday. The program, led by biotechnology company Oxitec, will release roughly 2 million genetically altered mosquitoes in California and Florida to fend off other mosquitoes carrying deadly diseases like Zika, yellow fever, dengue and chikungunya, the company said in a press release. The Environmental Protection Agency (EPA) approved Oxitec’s plan on March 8. “Given the growing health threat this mosquito poses across the U.S., we’re working to make this technology available and accessible,” Oxitec chief executive officer Grey Frandsen said in the press release.
Florida Begins Release of Genetically Altered Mosquitoes to Prevent Spread of Zika
20632Entrepreneur staff, Entrepreneur, 2022-03-11 08:01:36.
Since 2016, Zika , a disease transmitted by a virus that spreads an invasive species of mosquito, has plagued various regions of the world, including areas of Florida and Texas in the United States. In May 2020, the Environmental Protection Agency (EPA) approved a program to release millions of genetically altered mosquitoes that, in theory, will help reduce the population of female Aedes aegypti specimens, the species that carries the virus. n 2016, the disease became a public health issue throughout the world and caused multiple cases of a condition called microcephaly, in babies of women who were infected during pregnancy. Infected babies were born with smaller heads than expected due to partial collapse of the skull and limited movement in some of their joints. The Zika virus has spread to more than 30 countries, including Bolivia, Brazil, Guatemala, Honduras, Venezuela, El Salvador, Mexico, and parts of the United States.This week the first step was taken in a program that, if successful, could culminate in the release of up to 750 million genetically altered flies that would help control the spread of the disease. The first phase will last 12 weeks and will consist of introducing up to 12,000 genetically modified eggs in small areas. In theory, the specimens that hatch from these eggs are capable of transmitting a gene that only kills the females (they are the ones that bite and infect people) before they reach adulthood and start biting.
2 Billion Genetically Modified Mosquitoes Have Been Approved For Release In Florida And California
20609J. U. Nisa, Wonder Engineering, 2022-03-10 12:21:31.
The US Environmental Protection Agency (EPA) has sanctioned the release of 2 billion genetically modified mosquitos in Florida and California, Oxitec, the company that created the genetically modified mosquitoes, said. Oxitec’s experimental program intends to reduce the spread of hazardous diseases like dengue, Zika, and yellow fever by destroying the offspring of a common type of mosquito, Aedes aegypti, which transmits diseases through its sting. Scientists at Oxitec, located in the United Kingdom, mass generate and genetically engineer male Aedes aegypti eggs in a lab. These male mosquitos will be released into the wild to mate with females and pass on a gene that kills the female offspring, which are the only ones that sting and carry disease. The male offspring survive.
Billions of genetically modified male mosquitos will be released in California and Florida as a ‘natural pest control’ to stop the spread of diseases like Zika, yellow fever and Dengue
20599R. Morrison, Daily Mail, 2022-03-10 12:07:54.
Billions of genetically engineered male mosquitos will be released in California and Florida over the next two years, as part of a mission to kill off biting females. Oxitec, based in Oxford UK, is a biological pest control development firm, that has produced the edited version of the flying insects to combat mosquito-borne diseases like Dengue, yellow fever and Zika. Male Aedes aegypti mosquitos don't bite humans, but females do, and so the genetic modification causes females to die off soon after being born. The project has been cleared by the Environmental Protection Agency (EPA), and the first wave is due to be released this year, although it isn't clear exactly when this will happen, as it requires state regulatory approval in Florida and California. It isn't likely to be a problem in Florida, as the state played host to a trial last year that saw millions of the same type of Oxitec mosquitos released in the Florida Keys.
2 billion genetically modified mosquitos are about to be released in the US
20635J. Hawkins, yahoo, 2022-03-10 08:06:35.
Scientists have been playing god with mosquitos for a couple of years now. Back in 2021, British company Oxitec released 750 million lab-modified mosquitos in Florida. Now, the company is gearing up to release another 2 billion genetically modified mosquitos across more of Florida and in California as well.The new species, codenames OX5034, is made up entirely of male mosquitos. The new species is derived from the Aedes aegypti family of mosquitos. Just like others the company has released, this new 2 billion should produce larvae that die off before they reach adulthood. This is thanks to the self-limiting gene that Oxitec has created. The new gene essentially disrupts the generation of essential proteins the larvae need to develop. Without the needed proteins, it is unable to complete its development process.
Wolbachia wAlbB inhibits bluetongue and epizootic hemorrhagic fever viruses in Culicoides midge cells
20630M. L. Matthews, H. O. Covey, B. S. Drolet and C. L. Brelsfoard, Medical and Veterinary Entomology, 2022-03-10 07:56:14.
Abstract Culicoides midges are hematophagous insects that transmit arboviruses of veterinary importance. These viruses include bluetongue virus (BTV) and epizootic hemorrhagic fever virus (EHDV). The endosymbiont Wolbachia pipientis Hertig spreads rapidly through insect host populations and has been demonstrated to inhibit viral pathogen transmission in multiple mosquito vectors. Here, we have demonstrated a replication inhibitory effect on BTV and EHDV in a Wolbachia (wAlbB strain)-infected Culicoides sonorensis Wirth and Jones W8 cell line. Viral replication was significantly reduced by day 5 for BTV and by day 2 for EHDV as detected by real-time polymerase chain reaction (RT-qPCR) of the non-structural NS3 gene of both viruses. Evaluation of innate cellular immune responses as a cause of the inhibitory effect showed responses associated with BTV but not with EHDV infection. Wolbachia density also did not play a role in the observed pathogen inhibitory effects, and an alternative hypothesis is suggested. Applications of Wolbachia-mediated pathogen interference to impact disease transmission by Culicoides midges are discussed.
2 Billion Genetically Altered Mosquitoes Will Be Released in Fla. and Calif. to Fight Disease
20628A. Adams, People, 2022-03-10 07:50:39.
Billions of genetically modified mosquitoes are expected to be released within the next two years as part of an expanded version of an Environmental Protection Agency (EPA) study — but the project is receiving criticism from advocacy groups that believe it could be dangerous.The EPA said in an announcement on Monday that it will extend its current study into reducing the population of the Aedes aegypti, a mosquito commonly found in the United States, through April 2024. The EPA looking to broaden its work to Monroe County in Florida and four counties in California: Stanislaus, Fresno, Tulare and San Bernardino. Under the project's revised Experimental Use Permit (EUP), the EPA is permitted to release nearly 2.5 billion Aedes aegypti mosquitoes containing a protein called Tetracycline Trans-Activator Variant (tTAV-OX5034) into the wild.
Genetically modified mosquitoes could be tested in California soon
20605S. Milius, Science News, 2022-03-09 12:15:25.
Genetically modified mosquitoes might soon be whining on both U.S. coasts. The U.S. Environmental Protection Agency has approved two more years of testing Oxitec’s genetically modified mosquitoes as living pest controls, continuing a pilot program started in 2021 in the Florida Keys and expanding it to up to four counties in California. Now the Florida and California state governments will consider whether to grant permission. The male mosquitoes, OX5034 Aedes aegypti engineered by the biotech company Oxitec, carry daughter-killing genes that get passed generation to generation. When these males mate with local females outside a lab, only the sons should survive. Those inheriting the sabotage gene will grow up to mate with normal females, dooming their daughters too.
Why millions of genetically modified mosquitoes could be released across US
20601J. Rogers, New York Post, 2022-03-09 12:11:08.
The US could soon be swarming with genetically altered mosquitoes after the Environmental Protection Agency approved a plan to test the insects. It is hoped the new altered mosquitoes will ward off their natural, disease-causing counterparts. Biotechnology company Oxitec has developed altered Aedes aegypti mosquitoes which have been genetically modified so that males, which do not bite, are released into the wild and mate with females, which do bite. Their offspring, either male or female, never survive to reach maturity, according to the company.
Genetically Modified Mosquitoes May Be Released in Fla and Calif
20597R. Ellis, WebMD, 2022-03-09 12:04:50.
The U.S. Environmental Protection Agency has approved the release of 2 billion genetically altered mosquitoes in Florida and California, the company that created the genetically modified mosquitoes said. The experimental program created by Oxitec is designed to reduce the transmission of harmful diseases such as dengue, Zika, and yellow fever. The program is an extension of one in which millions of mosquitoes were released last year in the Florida Keys, USA Today reported. State agencies in Florida and California will have to approve the programs before the releases occur. The aim of the program is to reduce cases of diseases like yellow fever by killing off the offspring of a common kind of mosquito, Aedes aegypti, which spreads diseases through its bite.
2 Billion Genetically Modified Mosquitoes Cleared for Release in California and Florida
20595E. Cara, gizmodo, 2022-03-09 11:59:00.
British biotech firm Oxitec announced this week that it has received approval from the U.S. Environmental Protection Agency for its genetically modified mosquitoes to be released in parts of Florida and in California, following the completion of a pilot program last year. The modified male insects are designed to produce infertile offspring, ideally reducing local populations and rates of mosquito-borne illness. The male mosquitoes developed by Oxitec—codenamed species OX5034—are derived from Aedes aegypti, a notorious carrier of many diseases, including Zika, dengue, and yellow fever. When these mosquitoes mate with the native females in an area, they’re said to produce female larvae that simply die off before reaching adulthood, thus dooming the population as a whole. And because only female mosquitoes bite and suck blood from humans, the modified insects are thought to pose no danger to people.
Genetically Modified Mosquitoes Set to Be Released in California and Florida
20591K. Roberts, The Epoch Times, 2022-03-09 11:33:43.
Millions of genetically modified mosquitoes are set to be released in California and Florida in an effort to reduce the number of real, disease-carrying invasive mosquitoes. The U.S. Environmental Protection Agency on Monday approved use of the genetically engineered insects in pilot projects in specific districts across both states. The mosquitoes were made by UK-based biotechnology firm Oxitec, which is funded by the Bill and Melinda Gates Foundation, in an effort to combat insect-borne diseases such as dengue fever, yellow fever, and the Zika virus. According to Oxitec, its “sustainable and targeted biological pest control technology does not harm beneficial insects like bees and butterflies and is proven to control the disease-transmitting Aedes aegypti mosquito, which has invaded communities in Florida, California, and other U.S. states.” Since it was first detected in California in 2013, the Aedes aegypti mosquito has spread rapidly to more than 20 counties throughout the state, increasing the risk of mosquito-borne diseases being transmitted to humans.
No Sting in the Tail for Sterile Bisex Queensland Fruit Fly (Bactrocera tryoni Froggatt) Release Programs
20589O. L. Reynolds, D. Collins, B. C. Dominiak and T. Osborne, Insects, 2022-03-09 11:29:49.
Global markets do not tolerate the presence of fruit fly (Tephritidae) in horticultural produce. A key method of control for tephritidae pests, is the sterile insect technique (SIT). Several countries release a bisex strain, i.e., males and females, however the sterile male is the only sex which contributes to wild population declines when released en masse. In commercial orchards, there are concerns that sterile females released as part of bisex strains, may oviposit, i.e., ‘sting’ and cause damage to fruit, rendering it unmarketable. Australia has released a bisex strain of sterile Queensland fruit fly, Bactrocera tryoni Froggatt, for several decades to suppress wild pest populations, particularly in peri-urban and urban environments. Here, we assessed fruit damage in two commercially grown stone fruit orchards where bisex sterile B. tryoni were released, and in an orchard that did not receive sterile flies. The number of detected stings were higher in only one SIT release orchard, compared with the control; however, there was no difference between SIT and control orchards in the number of larvae detected. We showed that there is no evidence that sterile female B. tryoni released in large numbers caused stings, or damage that led to downgraded or unsaleable fruit. The bisex strain of sterile B. tryoni is recommended for use in commercial stone-fruit orchards, under the conditions in which this trial was conducted.
Proposed moquito release for Tulare County draws concern
20584E. Smith, The Business Journal, 2022-03-08 11:20:42.
News of the approval to release genetically-modified mosquitoes in Tulare County and Monroe County, Florida has drawn the ire of activists who say the company behind the project has not provided data demonstrating the insects are safe. At the same time, the company says it has the studies to demonstrate the safety of the program it calls “another tool in the integrated approach to pest control.” The U.S. Environmental Protection Agency has granted U.K.-based Oxitec an experimental-use permit giving the company the first green light to release male, non-biting mosquitoes in Tulare County and Monroe County in Florida, according to Rajeev Vaidyanathan, director of operations for Oxitec. The test is to see whether the engineered mosquitoes can reduce the number of Aedes aegypti mosquitoes that have spread throughout the country with the potential to carry tropical diseases such as dengue, yellow fever, Zika and chikungunya. Before they can begin the program, the California Department of Pesticide Regulations has to approve the proposal.
Millions of genetically modified mosquitoes may soon be buzzing in Florida and California. Here’s why.
20582R. W. Miller, USA Today, 2022-03-08 11:13:28.
Millions of genetically altered mosquitoes that seek to ward off their natural, disease-causing counterparts may soon be released in Florida and California after the Environmental Protection Agency approved a plan to further test the modified insects. Developed by the biotechnology company Oxitec, the Aedes aegypti mosquitoes are genetically modified so that males, which do not bite, are released into the wild and mate with females, which do bite. Their offspring are either male or females that never survive to reach maturity, the company says. Millions of the mosquitoes were released in the Florida Keys in a pilot project last year, and the EPA has authorized the extension of the project in Florida as well as the expansion into four counties in California, pending approval from the states' regulators.
‘Halt this nightmare immediately’: EPA approves release of genetically-engineered mosquitoes
20579J. Corbett, AlterNet, 2022-03-08 11:05:13.
Environmental and public health advocates responded with alarm after the Biden administration on Monday gave a British biotechnology company a green light to unleash billions of genetically engineered mosquitoes in the United States. The Environmental Protection Agency (EPA) granted Oxitec an experimental use permit that could lead to the release of genetically engineered (GE) mosquitoes in four California counties and extend a widely criticized program in Florida's Monroe County. While the release is intended to investigate whether the GE mosquito can reduce the population of Aedes aegypti mosquitoes—which carry various viruses—the species is not common in California and there are no reported cases of the targeted diseases. "This experiment is unnecessary and even dangerous, as there are no locally acquired cases of dengue, yellow fever, chikungunya, or Zika in California," declared Jaydee Hanson, policy director for the International Center for Technology Assessment and Center for Food Safety. Oxitec's altered male mosquitoes are supposed to pass on a gene that causes their offspring to die before reaching maturity. However, a peer-reviewed study published in September 2019 by Yale University researchers showed that releasing the GE mosquitoes in Brazil not only failed to reduce populations of Aedes aegypti but also resulted in hybrid mosquitoes.
Genetically Engineered Mosquito Imminent Mass Release Ignores Science, Public Health and Environmental Risks
20577H. Bourque, Friends of the Earth, 2022-03-07 11:00:22.
In defiance of science and public health concerns, today the Environmental Protection Agency (EPA) approved the mass release of billions of experimental genetically engineered (GE) mosquitoes into the United States’ most populous and agriculturally significant states. The biotechnology company Oxitec was granted an Experimental Use Permit for the release of a genetically engineered version of the species Aedes aegypti across Fresno, Tulare, San Bernadino and Stanislaus Counties in California and in Monroe County in Florida. This will be the biggest release of GE insects in the world. EPA’s approval came despite growing concerns raised by scientists, public health experts and environmental groups about potential impacts of the experimental releases to public health, the environment and endangered species. No publicly available data supports Oxitec’s claims that GE mosquitoes will reduce incidence of mosquito borne diseases. An independent peer-reviewed study from Yale University scientists revealed that over two years of continual releases of the GE mosquitoes at a test site in Brazil failed to reduce populations of Aedes aegypti. The Yale study also found that the GE mosquitoes bred with local Aedes aegypti, resulting in hybrid mosquitoes in the wild that may be more aggressive, more difficult to eradicate and may increase the spread of mosquito-borne disease.
Selfish migrants: How a meiotic driver is selected to increase dispersal
20575J. N. Runge, H. Kokko and A. K. Lindholm, J Evol Biol, 2022-03-07 10:54:44.
Meiotic drivers are selfish genetic elements that manipulate meiosis to increase their transmission to the next generation to the detriment of the rest of the genome. One example is the t haplotype in house mice, which is a naturally occurring meiotic driver with deleterious traits-poor fitness in polyandrous matings and homozygote inviability or infertility-that prevent its fixation. Recently, we discovered and validated a novel effect of t in a long-term field study on free-living wild house mice and with experiments: t-carriers are more likely to disperse. Here, we ask what known traits of the t haplotype can select for a difference in dispersal between t-carriers and wildtype mice. To that end, we built individual-based models with dispersal loci on the t and the homologous wildtype chromosomes. We also allow for density-dependent expression of these loci. The t haplotype consistently evolves to increase the dispersal propensity of its carriers, particularly at high densities. By examining variants of the model that modify different costs caused by t, we show that the increase in dispersal is driven by the deleterious traits of t, disadvantage in polyandrous matings and lethal homozygosity or male sterility. Finally, we show that an increase in driver-carrier dispersal can evolve across a range of values in driver strength and disadvantages.
GMO mosquitoes set for release in California to quell disease
20572M. Renda, Courthouse News Service, 2022-03-07 10:48:47.
The U.S. Environmental Protection Agency approved the experimental use of genetically engineered mosquitoes in California and Florida to reduce the populations of invasive mosquitoes that carry a host of infectious diseases like Zika and dengue fever. “With mosquito and vector-borne diseases a growing concern in California, we see Oxitec’s technology as an important additional option to control the invasive Aedes aegypti mosquito,” said Dr. Mustapha Debboun, general manager of the Delta Mosquito and Vector Control District, a government agency in the Central Valley. “We look forward to working in partnership with Oxitec and have been impressed with results from their previous projects in Brazil and the Florida Keys.” The Aedes aegypti mosquitoes were historically relegated to tropical and subtropical zones but have since invaded every continent on Earth except Antarctica. They are capable of bringing the diseases that plague tropical regions with them.
Gene drives and population persistence vs elimination: The impact of spatial structure and inbreeding at low density
20529P. J. Beaghton and A. Burt, Theoretical Population Biology, 2022-03-03 08:28:52.
Synthetic gene drive constructs are being developed to control disease vectors, invasive species, and other pest species. In a well-mixed random mating population a sufficiently strong gene drive is expected to eliminate a target population, but it is not clear whether the same is true when spatial processes play a role. In species with an appropriate biology it is possible that drive-induced reductions in density might lead to increased inbreeding, reducing the efficacy of drive, eventually leading to suppression rather than elimination, regardless of how strong the drive is. To investigate this question we analyse a series of explicitly solvable stochastic models considering a range of scenarios for the relative timing of mating, reproduction, and dispersal and analyse the impact of two different types of gene drive, a Driving Y chromosome and a homing construct targeting an essential gene. We find in all cases a sufficiently strong Driving Y will go to fixation and the population will be eliminated, except in the one life history scenario (reproduction and mating in patches followed by dispersal) where low density leads to increased inbreeding, in which case the population persists indefinitely, tending to either a stable equilibrium or a limit cycle. These dynamics arise because Driving Y males have reduced mating success, particularly at low densities, due to having fewer sisters to mate with. Increased inbreeding at low densities can also prevent a homing construct from eliminating a population. For both types of drive, if there is strong inbreeding depression, then the population cannot be rescued by inbreeding and it is eliminated. These results highlight the potentially critical role that low-density-induced inbreeding and inbreeding depression (and, by extension, other sources of Allee effects) can have on the eventual impact of a gene drive on a target population.
EVITA Dengue: a cluster-randomized controlled trial to EValuate the efficacy of Wolbachia-InfecTed Aedes aegypti mosquitoes in reducing the incidence of Arboviral infection in Brazil
20526M. H. Collins, G. E. Potter, M. D. T. Hitchings, E. Butler, M. Wiles, J. K. Kennedy, S. B. Pinto, A. B. M. Teixeira, A. Casanovas-Massana, N. G. Rouphael, G. A. Deye, C. P. Simmons, L. A. Moreira, M. L. Nogueira, D. A. T. Cummings, A. I. Ko, M. M. Teixeir, Trials, 23:185. 2022-03-02 08:20:38.
BACKGROUND: Arboviruses transmitted by Aedes aegypti including dengue, Zika, and chikungunya are a major global health problem, with over 2.5 billion at risk for dengue alone. There are no licensed antivirals for these infections, and safe and effective vaccines are not yet widely available. Thus, prevention of arbovirus transmission by vector modification is a novel approach being pursued by multiple researchers. However, the field needs high-quality evidence derived from randomized, controlled trials upon which to base the implementation and maintenance of vector control programs. Here, we report the EVITA Dengue trial design (DMID 17-0111), which assesses the efficacy in decreasing arbovirus transmission of an innovative approach developed by the World Mosquito Program for vector modification of Aedes mosquitoes by Wolbachia pipientis. METHODS: DMID 17-0111 is a cluster-randomized trial in Belo Horizonte, Brazil, with clusters defined by primary school catchment areas. Clusters (n = 58) will be randomized 1:1 to intervention (release of Wolbachia-infected Aedes aegypti mosquitoes) vs. control (no release). Standard vector control activities (i.e., insecticides and education campaigns for reduction of mosquito breeding sites) will continue as per current practice in the municipality. Participants (n = 3480, 60 per cluster) are children aged 6-11 years enrolled in the cluster-defining school and living within the cluster boundaries who will undergo annual serologic surveillance for arboviral infection. The primary objective is to compare sero-incidence of arboviral infection between arms. DISCUSSION: DMID 17-0111 aims to determine the efficacy of Wolbachia-infected mosquito releases in reducing human infections by arboviruses transmitted by Aedes aegypti and will complement the mounting evidence for this method from large-scale field releases and ongoing trials. The trial also represents a critical step towards robustness and rigor for how vector control methods are assessed, including the simultaneous measurement and correlation of entomologic and epidemiologic outcomes. Data from this trial will inform further the development of novel vector control methods. TRIAL REGISTRATION: ClinicalTrials.gov NCT04514107 . Registered on 17 August 2020 Primary sponsor: National Institute of Health, National Institute of Allergy and Infectious Diseases.
New tech fights fall armyworm by letting offspring die
20568V. Ouma, Sci Dev Net, 2022-03-01 09:43:19.
Scientists have developed a new technology that could control the devastating fall armyworm crop pest by releasing genetically-controlled males that suppress populations as subsequent offspring cannot survive, a study says. The fall armyworm, Spodoptera frugiperda, which was detected in Sub-Saharan Africa for the first time in 2016, could lead to one-third maize yield losses in some countries and up to US$6.3 billion loss annually, according to the study published in the journal BMC Biotechnology. The gene technology developed by Oxitec, a UK-based biotechnology company that genetically modifies insects to assist in insect control, enables production of male-only cohorts of the friendly fall armyworm that when released into farmer fields will mate with pest female fall armyworms, and their female offspring cannot survive, resulting in fewer pests on the crops and therefore less damage
Increased biting rate and decreased Wolbachia density in irradiated Aedes mosquitoes
20487R. Moretti, E. Lampazzi, C. Damiani, G. Fabbri, G. Lombardi, C. Pioli, A. Desiderio, A. Serrao and M. Calvitti, Parasites and Vectors, 15:67. 2022-02-24 08:48:28.
Releasing considerable numbers of radiation-sterilized males is a promising strategy to suppress mosquito vectors. However, releases may also include small percentages of biting females, which translate to non-negligible numbers when releases are large. Currently, the effects of irradiation on host-seeking and host-biting behaviors have not been exhaustively investigated. Information is also lacking regarding the effects of sterilizing treatment on the endosymbiotic bacterium Wolbachia, which is known to affect the vector competence of infected mosquitos.
Evaluation of anti-malaria potency of wild and genetically modified Enterobacter cloacae expressing effector proteins in Anopheles stephensi
20485H. Dehghan, S. H. Mosa-Kazemi, B. Yakhchali, N. Maleki-Ravasan, H. Vatandoost and M. A. Oshaghi, Parasites and Vectors, 15:63. 2022-02-19 08:43:23.
Malaria is one of the most lethal infectious diseases in tropical and subtropical areas of the world. Paratransgenesis using symbiotic bacteria offers a sustainable and environmentally friendly strategy to combat this disease. In the study reported here, we evaluated the disruption of malaria transmission in the Anopheles stephensi-Plasmodium berghei assemblage using the wild-type (WT) and three modified strains of the insect gut bacterium, Enterobacter cloacae.
Considerations for homology-based DNA repair in mosquitoes: Impact of sequence heterology and donor template source
20478J. X. D. Ang, K. Nevard, R. Ireland, D.-K. Purusothaman, S. A. N. Verkuijl, L. Shackleford, E. Gonzalez, M. A. E. Anderson and L. Alphey, PLOS Genetics, 18:e1010060. 2022-02-18 08:29:29.
Author summary The field of genetic control of mosquito vectors has progressed rapidly in recent years, especially in Cas9-based control systems, due to its robustness to elicit a species-specific and dispersive control of mosquito population. To generate a Cas9-based integration, Cas9 and sgRNA are used to cleave a chromosomal locus while a plasmid DNA donor, containing a genetic cargo flanked by sequences homologous to the chromosomal locus, is supplied as a repair template. This results in the cargo being copied into the genome through HDR. This form of integration, however, is currently one of the major bottlenecks for researchers as it involves a laborious process of microinjecting mosquito embryos and has rather low integration rates. In this study, we assessed the effects of homologous sequence mismatches and various donor template forms (i.e. plasmid, ssDNA, biotinylated ds/ssDNA) on HDR. We found that sequence mismatches and non-plasmid donors reduced the efficiency and integrity of integration, respectively. By analysing the direction and length of homologous sequence that was copied into the genome concurrently with the cargo, we inferred the mechanism responsible for the integrations observed in our study. These findings will be useful to guide future construct designs for optimal HDR rates in mosquitoes.
First ever gene-edited ticks offer new weapons against Lyme disease
20524N. Lavars, New Atlas, 2022-02-16 08:14:12.
Gene editing in ticks had been thought to be impossible until now, and with good reason. Tick embryos are very tricky to inject because the egg that contains them has a tough layer on the outside, high pressure levels inside, and is also coated in a waxy layer the mothers create using what's called the Gené's organ."Despite their capacity to acquire and pass on an array of debilitating pathogens, research on ticks has lagged behind other arthropod vectors, such as mosquitoes, largely because of challenges in applying available genetic and molecular tools," said Monika Gulia-Nuss, a co-senior author of the study and a molecular biologist at the University of Nevada, Reno. Gulia-Nuss and her research team, which included scientists from the University of Maryland and Penn State University, believe they have finally cracked the code. The first step in the breakthrough technique involves ablating the Gené's organ to prevent the formation of the waxy coating. The eggs were then treated with chemicals benzalkonium chloride and sodium chloride to both eliminate the tough protective layer and lower the pressure inside the eggs.
C-type lectin 4 regulates broad-spectrum melanization-based refractoriness to malaria parasites
20489M. L. Simões, Y. Dong, G. Mlambo and G. Dimopoulos, PLOS Biology, 20:e3001515. 2022-02-13 08:53:42.
Anopheles gambiae melanization-based refractoriness to the human malaria parasite Plasmodium falciparum has rarely been observed in either laboratory or natural conditions, in contrast to the rodent model malaria parasite Plasmodium berghei that can become completely melanized by a TEP1 complement-like system-dependent mechanism. Multiple studies have shown that the rodent parasite evades this defense by recruiting the C-type lectins CTL4 and CTLMA2, while permissiveness to the human malaria parasite was not affected by partial depletion of these factors by RNAi silencing. Using CRISPR/Cas9-based CTL4 knockout, we show that A. gambiae can mount melanization-based refractoriness to the human malaria parasite, which is independent of the TEP1 complement-like system and the major anti-Plasmodium immune pathway Imd. Our study indicates a hierarchical specificity in the control of Plasmodium melanization and proves CTL4 as an essential host factor for P. falciparum transmission and one of the most potent mosquito-encoded malaria transmission-blocking targets.
piggyBac-based transgenic RNAi of serine protease 2 results in male sterility in Hyphantria cunea
20313X. Li, Q. Liu, H. Bi, Y. Wang, X. Xu, W. Sun, Z. Zhang and Y. Huang, Insect Biochemistry and Molecular Biology, 103726. 2022-02-05 08:57:08.
Fall webworm, Hyphantria cunea, is a global invasive forest pest that causes serious damage to the economy and ecosystem of agriculture and forestry. Due to the extent of the problem and the difficulty of conventional chemical control, new technologies must be pursued, such as genetic-based inheritable insect sterile technology (gSIT), which exhibits promise for pest control. In the present study, we established a piggyBac-based transgenic system in fall webworm and generated a dominant male-sterile strain by targeting the seminal fluid protein serine protease 2 (Hcser2), displaying an outstanding trait of gSIT. First, an RNA polymerase type III (Pol III) promoter, the HcU62 small nuclear RNA (snRNA) gene promoter, was identified and characterized through direct injection of RNAi plasmids in vivo. Quantitative real-time PCR revealed that HcU62 had the greatest knockdown efficiency of the Hcyellow gene among five short hairpin RNA (shRNA) plasmids tested, designated HcU61–HcU65. Subsequent application of piggyBac-based transgenic RNAi (HcU62: shHcyellow, Ysh2) significantly reduced the expression level of the Hcyellow gene, resulting in a stable yellow observable phenotype from the larval to pupal stages in Ysh2 transgenic mutants. Finally, an HcU62-driven transgenic RNAi strain targeting the Hcser2 gene was obtained, resulting in a dominant male-sterile phenotype. Significantly, this process did not affect the growth, development, mating behavior or egg laying of the mutants, and the dominant sterile trait could be inherited in the next generation through female Hcser2 mutants. Furthermore, CRISPR/Cas9-mediated disruption of the Hcser2 gene further confirmed the dominant sterile phenotype, supporting it as a generalized target for genetic control of H. cunea. This study reports the first piggyBac-mediated transgenic system in H. cunea, providing a promising genetic method for controlling this pest by targeting Hcser2 gene.
Genetically engineered insects with sex-selection and genetic incompatibility enable population suppression
20286A. Upadhyay, N. R. Feltman, A. Sychla, A. Janzen, S. R. Das, M. Maselko and M. Smanski, eLife, 11. 2022-02-02 11:49:30.
Engineered Genetic Incompatibility (EGI) is a method to create species-like barriers to sexual reproduction. It has applications in pest control that mimic Sterile Insect Technique when only EGI males are released. This can be facilitated by introducing conditional female-lethality to EGI strains to generate a sex-sorting incompatible male system (SSIMS). Here, we demonstrate a proof of concept by combining tetracycline-controlled female lethality constructs with a pyramus-targeting EGI line in the model insect Drosophila melanogaster. We show that both functions (incompatibility and sex-sorting) are robustly maintained in the SSIMS line and that this approach is effective for population suppression in cage experiments. Further we show that SSIMS males remain competitive with wild-type males for reproduction with wild-type females, including at the level of sperm competition.
A flavivirus-inducible gene expression system that modulates broad-spectrum antiviral activity against dengue and Zika viruses
20281S.-C. Weng, Y.-X. Zhou and S.-H. Shiao, Insect Biochemistry and Molecular Biology, 142:103723. 2022-02-02 11:40:32.
Incidence of dengue virus (DENV) and Zika virus (ZIKV), two mosquito-borne flaviviruses, is increasing in large parts of the world. Vaccination and medication for these diseases are unsatisfactory. Here, we developed a novel antiviral approach, using a virus-inducible gene expression system, to block virus replication and transmission. Constructs containing the smallest replication units of dengue virus serotype 2 (DENV2) with negative-stranded DENV2 artificial genomes and genes of interest were established in an Aedes aegypti cell line, resulting in expression of target genes after DENV2 infection. Green fluorescent protein (GFP) assays confirmed the system was virus-inducible. When we used one of two apoptosis-related genes, A. aegypti michelob_x (AaMx) and inhibitor of apoptosis (IAP)-antagonist michelob_x-like protein (AaIMP) instead of GFP, the production of viral RNA and proteins were inhibited for all five viruses tested (DENV1–4 and ZIKV), and effector caspase activity was induced. The system thus inhibited the production of infectious virus particles in vitro, and in mosquitoes it did so after DENV2 infection. This is a novel broad-spectrum antiviral approach using a flavivirus-inducible gene-expression system, which could lead to new avenues for mosquito-borne disease control.
Conditions for Investment in Genetic Biocontrol of Pest Vertebrates in Australia
20264L. Carter, A. Mankad, S. Campbell, W. Ruscoe, K. P. Oh, P. R. Brown, M. Byrne, M. Tizard and T. Strive, Frontiers in Agronomy, 3. 2022-01-31 08:46:53.
Managing pest vertebrate species in Australia is a significant challenge for government, industry, research sectors and land-managers. Innovative tools such as genetic biocontrol offers decision-makers a potentially effective means of reducing the impact of pest species incursions. To determine the conditions for investment in genetic biocontrol, we applied qualitative engagement methodologies to identify and integrate existing knowledge of pest species research and management in Australia. Two facilitated workshops were held to determine key topics related to genetic biocontrol technologies for selected pest species. The topics explored during workshop discussions included: identifying existing knowledge gaps; risk perceptions; social and ethical considerations and; industry and business considerations. The workshops' aim was to assess the potential, the priorities and the risk parameters among expert stakeholders and decision-makers for using genetic biocontrol approaches to reduce the impacts of key pest species in Australia. This paper reports on the design, process and outcomes of each workshop to inform the creation of a decision framework. Stakeholders were cautiously optimistic of pursuing continued research and development for vertebrate pest management in Australia. However, employing an appropriate, transparent process for incorporating diverse stakeholder perspectives on genetic biocontrol technologies is essential to ensure their development and use remains supported. This outcome will require meaningful investment in both social science investigations and well-considered engagement processes concurrent with biotechnology development globally.
Self-limiting fall armyworm: a new approach in development for sustainable crop protection and resistance management
20232C. E. Reavey, A. S. Walker, S. P. Joyce, L. Broom, A. Willse, K. Ercit, M. Poletto, Z. H. Barnes, T. Marubbi, B. J. Troczka, D. Treanor, K. Beadle, B. Granville, V. de Mello, J. Teal, E. Sulston, A. Ashton, L. Akilan, N. Naish, O. Stevens, N. Humphreys-Jo, BMC Biotechnology, 22:5. 2022-01-27 09:04:56.
Here, we describe the first germline transformation of the fall armyworm and the development of a genetically engineered male-selecting self-limiting strain, OX5382G, which exhibits complete female mortality in the absence of an additive in the larval diet. Laboratory experiments showed that males of this strain are competitive against wild-type males for copulations with wild-type females, and that the OX5382G self-limiting transgene declines rapidly to extinction in closed populations following the cessation of OX5382G male releases. Population models simulating the release of OX5382G males in tandem with Bt crops and non-Bt ‘refuge’ crops show that OX5382G releases can suppress fall armyworm populations and delay the spread of resistance to insecticidal proteins
Monitoring Needs for Gene Drive Mosquito Projects: Lessons From Vector Control Field Trials and Invasive Species
20177G. Rašić, N. F. Lobo, E. H. Jeffrey Gutiérrez, C. H. Sánchez and J. M. Marshall, Frontiers in Genetics, 12:780327. 2022-01-25 09:18:49.
As gene drive mosquito projects advance from contained laboratory testing to semi-field testing and small-scale field trials, there is a need to assess monitoring requirements to: i) assist with the effective introduction of the gene drive system at field sites, and ii) detect unintended spread of gene drive mosquitoes beyond trial sites, or resistance mechanisms and non-functional effector genes that spread within trial and intervention sites. This is of particular importance for non-localized gene drive projects, as the potential scale of intervention means that monitoring is expected to be more costly than research, development and deployment. Regarding monitoring needs for population replacement systems, lessons may be learned from experiences with Wolbachia-infected mosquitoes, and for population suppression systems, from experiences with releases of genetically sterile male mosquitoes. For population suppression systems, assessing monitoring requirements for tracking population size and detecting rare resistant alleles are priorities, while for population replacement systems, allele frequencies must be tracked, and pressing concerns include detection of gene drive alleles with non-functional effector genes, and resistance of pathogens to functional effector genes. For spread to unintended areas, open questions relate to the optimal density and placement of traps and frequency of sampling in order to detect gene drive alleles, drive-resistant alleles or non-functional effector genes while they can still be effectively managed. Invasive species management programs face similar questions, and lessons may be learned from these experiences. We explore these monitoring needs for gene drive mosquito projects progressing through the phases of pre-release, release and post-release.
A gene drive does not spread easily in populations of the honey bee parasite Varroa destructor
20173N. R. Faber, A. B. Meiborg, G. R. McFarlane, G. Gorjanc and B. A. Harpur, Apidologie, 52:1112-1127. 2022-01-25 09:13:37.
Varroa mites (Varroa destructor) are the most significant threat to beekeeping worldwide. They are directly or indirectly responsible for millions of colony losses each year. Beekeepers are somewhat able to control varroa populations through the use of physical and chemical treatments. However, these methods range in effectiveness, can harm honey bees, can be physically demanding on the beekeeper, and do not always provide complete protection from varroa. More importantly, in some populations varroa mites have developed resistance to available acaricides. Overcoming the varroa mite problem will require novel and targeted treatment options. Here, we explore the potential of gene drive technology to control varroa. We show that spreading a neutral gene drive in varroa is possible but requires specific colony-level management practices to overcome the challenges of both inbreeding and haplodiploidy. Furthermore, continued treatment with acaricides is necessary to give a gene drive time to fix in the varroa population. Unfortunately, a gene drive that impacts female or male fertility does not spread in varroa. Therefore, we suggest that the most promising way forward is to use a gene drive which carries a toxin precursor or removes acaricide resistance alleles. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13592-021-00891-5.
CRISPR Technology Can Eliminate Disease-Spreading Mosquitoes
20133S. Krishana, Now, 2022-01-19 13:10:41.
Scientists have uncovered a new technique they call the “precision-guided sterile insect technique,” or pgSIT. While most CRISPR procedures affect organisms that spread diseases by passing a gene change down generations, this system is more limited. It targets male mosquito genes that are linked to fertility. As a result of changing these genes, any offspring these mosquitoes have would be infertile. “pgSIT is a new scalable genetic control system that uses a CRISPR-based approach to engineer deployable mosquitoes that can suppress populations,” said Omar Akbari, one of the study’s authors. “Males don’t transmit diseases, so the idea is that, as you release more and more sterile males, you can suppress the population without relying on harmful chemicals and insecticides.” But it’s the female population that spreads diseases, so pgSIT targets them, as well. According to the study, the CRISPR technology treatment renders female mosquitoes unable to fly or hold their wings up. It also makes them slower and more lethargic in their movements. Combined, these effects lower the chances that these female mosquitoes will mate or successfully find a blood source and attach to it to spread disease.
The prince, the mayor, and the U.S. fish that ate Japan
20103C. Elliot, National Geographic, 2022-01-11 16:44:32.
When Crown Prince Akihito visited Chicago on October 3, 1960, his sole request was to visit Shedd Aquarium. Then Mayor Richard J. Daley, an avid angler, presented the prince with a gift that he scooped with a net from one of the tanks himself: 18 bluegills, the official Illinois state fish. The 26-year-old future emperor was already a passionate ichthyologist, and he planned to stock the exotic fish in the moat surrounding his palace, according to accounts in the Chicago Tribune at the time. At windy Chicago O’Hare International Airport the next day with Princess Michiko, Akihito bid the city farewell, carrying a gift that he couldn’t have imagined would cause a decades-long ecological crisis in his homeland. In the intervening six decades, the bluegills became an invasive, species-destroying nightmare, crowding Japanese freshwater lakes and rivers and destroying native fish biodiversity, says Kenji Saitoh, a researcher at the country’s Fisheries Resources and Education Agency. Fortunately, science has marched on in 60 years. Now, Japanese geneticists are experimenting with the gene editing wizardry of CRISPR to sterilize the invasive bluegills. If the initiative succeeds, wildlife managers could use the same technique to rid the U.S. of damaging aquatic invasives such as the Asian carp.
An Introduction to Containment Recommendations for Gene Drive Mosquitoes and the Laboratory Rearing of Genetically Engineered Mosquitoes in Africa
20044S. Higgs, Vector-Borne and Zoonotic Diseases, 2022-01-06 10:04:57.
The prospect of using genetically engineered arthropods to reduce the incidence of vector-borne diseases either indirectly by suppressing vector populations or directly by replacing wild-type vector species with less competent ones has long been discussed; however, only in the past few years has this become feasible. The advent of CRISPR/Cas9-based gene drive and its application to mosquitoes have been a critical factor in bringing the dream to reality, but with opportunity also comes responsibility. Safe and secure handling of genetically engineered arthropods under laboratory/insectary conditions was considered in the original and revised ACGs, and under field conditions by Benedict et al. (2008). Although not discussed in these ACGs, hence the need for this addendum, Benedict et al. (2018) discussed containment and management of gene drive arthropods as distinct from genetically modified mosquitoes under laboratory conditions. A prerequisite for the application of engineered mosquitoes for mosquito-borne disease control is the rearing of these mosquitoes in countries where releases will ultimately occur. In 2018, three companion articles were published in VBZ that discussed this very issue (Mumford et al. 2018, Quinlan et al. 2018a, 2018b), with James et al. (2020) discussing efficacy and safety criteria for advancing gene drive-modified mosquitoes to field testing. In this issue of VBZ, we publish two highly relevant articles that coincidentally, although submitted independently, are complementary.
Preparing an Insectary in Burkina Faso to Support Research in Genetic Technologies for Malaria Control
20042C. Guissou, M. M. Quinlan, R. Sanou, R. K. Ouédraogo, M. Namountougou and A. Diabaté, Vector-Borne and Zoonotic Diseases, 2022-01-06 09:53:59.
The Institut de Recherche en Sciences de la Santé (IRSS) of Burkina Faso, West Africa, was the first African institution to import transgenic mosquitoes for research purposes. A shift from the culture of mosquito research to regulated biotechnology research and considerable management capacity is needed to set up and run the first insectary for transgenic insects in a country that applied and adapted the existing biosafety framework, first developed for genetically modified (GM) crops, to this new area of research. The additional demands arise from the separate regulatory framework for biotechnology, referencing the Cartagena Protocol on Biosafety, and the novelty of the research strain, making public understanding and acceptance early in the research pathway important. The IRSS team carried out extensive preparations following recommendations for containment of GM arthropods and invested efforts in local community engagement and training with scientific colleagues throughout the region. Record keeping beyond routine practice was established to maintain evidence related to regulatory requirements and risk assumptions. The National Biosafety Agency of Burkina Faso, Agence Nationale de Biosécurité (ANB), granted the permits for import of the self-limiting transgenic mosquito strain, which took place in November 2016, and for conducting studies in the IRSS facility in Bobo-Dioulasso. Compliance with permit terms and conditions of the permits and study protocols continued until the conclusion of studies, when the transgenic colonies were terminated. All this required close coordination between management and the insectary teams, as well as others. This article outlines the experiences of the IRSS to support others undertaking such studies. The IRSS is contributing to the ongoing development of genetic technologies for malaria control, as a partner of Target Malaria (https://targetmalaria.org). The ultimate objective of the innovation is to reduce malaria transmission by using GM mosquitoes of the same species released to reduce the disease-vectoring native populations of Anopheles gambiae s.l.
Beyond the eye: Kynurenine pathway impairment causes midgut homeostasis dysfunction and survival and reproductive costs in blood-feeding mosquitoes
19915V. Bottino-Rojas, I. Ferreira, R. D. Nunes, X. Feng, T. B. Pham, A. Kelsey, R. Carballar-Lejarazú, V. Gantz, P. L. Oliveira and A. A. James, Insect Biochemistry and Molecular Biology, 103720. 2022-01-06 08:57:05.
Insect ommochrome biosynthesis pathways metabolize tryptophan to generate eye-color pigments and naturally occurring alleles of pathway genes are useful phenotypic markers in transgenesis studies. Pleiotropic effects of mutations in some genes exert a load on both survival and reproductive success in blood-feeding species. Here, we investigated the challenges imposed on mosquitoes by the increase of tryptophan resulting from blood meal digestion and the impact of disruptions of the ommochrome biosynthesis pathway. Female mosquitoes with spontaneous and induced mutations in the orthologs of the genes encoding kynurenine hydroxylase in Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus exhibited impaired survival and reproductive phenotypes that varied in type and severity among the species. A compromised midgut permeability barrier function was also observed in An. stephensi. Surprisingly, mutant mosquitoes displayed an increase in microbiota compared to controls that was not accompanied by a general induction of immune genes. Antibiotic treatment rescued some deleterious traits implicating a role for the kynurenine pathway (KP) in midgut homeostasis. Supplemental xanthurenic acid, a KP end-product, rescued lethality and limited microbiota proliferation in Ae. aegypti. These data implicate the KP in the regulation of the host/microbiota interface. These pleiotropic effects on mosquito physiology are important in the development of genetic strategies targeting vector mosquitoes.
Integrated control of Aedes albopictus in Southwest Germany supported by the Sterile Insect Technique
20046N. Becker, S. M. Langentepe-Kong, A. T. Rodriguez, T. T. Oo, D. Reichle, R. Luhken, J. Schmidt-Chanasit, P. Luthy, A. Puggioli and R. Bellini, Parasites and Vectors, 15:19. 2022-01-05 10:11:20.
Background: The invasive species Aedes albopictus, commonly known as the Asian tiger mosquito, has undergone extreme range expansion by means of steady introductions as blind passengers in vehicles traveling from the Mediterranean to south-west Germany. The more than 25 established populations in the State of Baden-Wurttemberg, Palatine and Hesse (south-west Germany) have become a major nuisance and public health threat. Aedes albopictus deserves special attention as a vector of arboviruses, including dengue, chikungunya and Zika viruses. In Germany, Ae. albopictus control programs are implemented by local communities under the auspices of health departments and regulatory offices. Methods: The control strategy comprised three pillars: (i) community participation (CP) based on the elimination of breeding sites or improved environmental sanitation, using fizzy tablets based on Bacillus thuringiensis israelensis (fizzy Bti tablets; Culinex (R) Tab plus); (ii) door-to-door (DtD) control by trained staff through the application of high doses of a water-dispersible Bti granular formulation (Vectobac (R) WG) aimed at achieving a long-lasting killing effect; and (iii) implementation of the sterile insect technique (SIT) to eliminate remaining Ae. albopictus populations. Prior to initiating large-scale city-wide treatments on a routine basis, the efficacy of the three elements was evaluated in laboratory and semi-field trials. Special emphasis was given to the mass release of sterile Ae. albopictus males. Results: More than 60% of the local residents actively participated in the first pillar (CP) of the large-scale control program. The most effective element of the program was found to be the DtD intervention, including the application of Vectobac (R) WG (3000 ITU/mg) to potential breeding sites (10 g per rainwater container, maximum of 200 I = maximum of approx. 150,000 ITU/I, and 2.5 g per container <50 I) with a persistence of at least 3 weeks. In Ludwigshafen, larval source management resulted in a Container Index for Ae. albopictus of < 1% in 2020 compared to 10.9% in 2019. The mean number of Aedes eggs per ovitrap per 2 weeks was 4.4 in Ludwigshafen, 18.2 in Metzgergrun (Freiburg) (SIT area) and 22.4 in the control area in Gartenstadt (Freiburg). The strong reduction of the Ae. albopictus population by Bti application was followed by weekly releases of 1013 (Ludwigshafen) and 2320 (Freiburg) sterile Ae. albopictus males per hectare from May until October, resulting in a high percentage of sterile eggs. In the trial areas of Ludwigshafen and Frieburg, egg sterility reached 84.7 +/- 12.5% and 62.7 +/- 25.8%, respectively; in comparison, the natural sterility in the control area was 14.6 +/- 7.3%. The field results were in line with data obtained in cage tests under laboratory conditions where sterility rates were 87.5 +/- 9.2% after wild females mated with sterile males; in comparison, the sterility of eggs laid by females mated with unirradiated males was only 3.3 +/- 2.8%. The overall egg sterility of about 84% in Ludwigshafen indicates that our goal to almost eradicate the Ae. albopictus population could be achieved. The time for inspection and treatment of a single property ranged from 19 to 26 min depending on the experience of the team and costs 6-8 euros per property. Conclusions: It is shown that an integrated control program based on a strict monitoring scheme can be most effective when it comprises three components, namely CP, DtD intervention that includes long-lasting Bti-larviciding to strongly reduce Ae. albopictus populations and SIT to reduce the remaining Ae. albopictus population to a minimum or even to eradicate it. The combined use of Bti and SIT is the most effective and selective tool against Ae. albopictus, one of the most dangerous mosquito vector species.
Stakeholder engagement to inform the risk assessment and governance of gene drive technology to manage spotted-wing drosophila
20212A. E. Kokotovich, S. K. Barnhill-Dilling, J. E. Elsensohn, R. Li, J. A. Delborne and H. Burrack, Journal of Environmental Management, 307:114480. 2022-01-04 15:32:08.
Emerging biotechnologies, such as gene drive technology, are increasingly being proposed to manage a variety of pests and invasive species. As one method of genetic biocontrol, gene drive technology is currently being developed to manage the invasive agricultural pest spotted-wing drosophila (Drosophila suzukii, SWD). While there have been calls for stakeholder engagement on gene drive technology, there has been a lack of empirical work, especially concerning stakeholder engagement to inform risk assessment. To help address this gap and inform future risk assessments and governance decisions for SWD gene drive technology, we conducted a survey of 184 SWD stakeholders to explore how they define and prioritize potential benefits and potential adverse effects from proposed SWD gene drive technology. We found that stakeholders considered the most important potential benefits of SWD gene drive technology to be: 1) Decrease in the quantity or toxicity of pesticides used, and 2) Decrease in SWD populations. Stakeholders were most concerned about the potential adverse effects of: 1) Decrease in beneficial insects, 2) Increase in non-SWD secondary pest infestations, and 3) Decrease in grower profits. Notably, we found that even stakeholders who expressed support for the use of SWD gene drive technology expressed concerns about potential adverse effects from the technology, emphasizing the need to move past simplistic, dichotomous views of what it means to support or oppose a technology. These findings suggest that instead of focusing on the binary question of whether stakeholders support or oppose SWD gene drive technology, it is more important to identify and assess the factors that are consequential to stakeholder decision making – including, for example, exploring whether and under what conditions key potential adverse effects and potential benefits would result from the use of SWD gene drive technology.
Intervention of Modern Genetic Tools for Managing Insect Pests of Fruit Crops
25476G. S. Miglani, S. Singh, Z. Li and R. K. Sandhu, Genetic Methods and Tools for Managing Crop Pests, 2022-01-01 09:00:36.
Merits and demerits of select modern genetic tools as sterile insect technique, repressible dominant lethal, engineering insect pests, transgenic crops, primary resistance management, gene silencing RNA interference, genome-editing-based methods, autocidal insect control techniques, and genomics approaches for pest management have been discussed. Application of these methods to manage insect pests of fruit crops have been dealt with. Finally, new vision to pest control and future prospects in the utilization of molecular genetics-based tools for insect pest management has been presented.
Newer Genetic Tools, Techniques, Vectors, Promoters, and Molecular Markers for Genetic Engineering of Herbivorous Insects
25474D. D. Rani, S. Subhash, H. R. Gopalkrishna and A. K. Chakravarthy, Genetic Methods and Tools for Managing Crop Pests, 2022-01-01 08:54:42.
Insects can transmit major infectious diseases to crop plants. Recent advances in insect genomics and transformation technology provide new strategies for the control of insect-borne pathogen transmission and insect pest management. One such strategy is the genetic modification of insects with genes that block pathogen development. Another is to suppress insect populations by releasing either sterile males or males carrying female-specific dominant lethal genes into the environment. Newer genetic tools and methods are described.
Scientists Used CRISPR Gene Editing to Choose the Sex of Mouse Pups
19906S. Fan, Singuarity Hub, 2021-12-23 08:37:01.
“Do you want a boy or a girl?” can be an awkward question.But in certain circles, it’s a question that’s asked every day. Take agriculture. In a perfect world, most cows would only birth females. Chicks would grow up to be all hens. “Sexing” a farm animal when they’re at a young age wouldn’t be a thing—especially when it means male animals, without the ability to produce milk or eggs, are often culled at a young age to preserve resources. There might be a better way. This month, a team tapped into the power of CRISPR to control the sex of the offspring in mice. By splicing CRISPR components into the parents’ genome, the team was able to flip on—or off—a switch that nearly perfectly determined the sex of their litters. Unlike previous attempts, the baby mice could go on to have litters of their own of both sexes. The targeted gene used for the edit is conserved across evolution, suggesting the technique could work in more animals than just mice. But it’s controversial. Essentially, the technique selectively kills off embryos of a certain sex, which immediately raises ethical red flags. For now, scientists aren’t concerned about the technology being used in humans due to its complexity. But the study is the latest to showcase biotech’s increasing ability to manipulate reproduction.
Interaction Between Entomology and Gene Technology: Bt-transgenic and Gene Drives for Pests Control .
20105J. C. Ndayıragıje, T. Özek, H. Çevik and İ. Karaca, Türk Bilim ve Mühendislik Dergisi, 3:108-115. 2021-12-22 17:00:56.
Pest control is the major agricultural activity for increasing crop productivity thus insuring food security. Recent pest management programs are depending too much on chemical pesticides, which are a threat to our health and environment. One of the greatest entomological achievements for the benefits of plant protection is the use of Bacillus thuringiensis to produce transgenic plants resisting pests. However, such organisms comprise inconveniences against human health and biodiversity in terms of genetic pollution. In many countries, the use of Genetically Modified Organisms is prohibited. This study review on integration of growing gene technology with actual scientific achievements can help to determine a sustainable solution to the pest’s problem. In this way, many literatures were referred on to comparatively criticize the effectiveness, safety and sustainability of gene drive over Bt transgenic based on scientific soundness. Gene drive technology is a new technic consisting of gene engineering and on-field monitoring of its transgenes. The case in point is the inappropriateness of Bt-transgenes. Practically, gene drive can be an alternative to Bacillus thuringiensis in pest control for increased safety and environmental protection.
Perspectives into Genetic Manipulations for Control of Dengue Vector (Aedes aegypti Linnaeus, 1762) with Reference to Progress in Indian Experiments
19975R. Chatterjee, S. Bhattacharya and B. K. Tyagi, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 11:46:45.
Vector-borne diseases like malaria, dengue, chikungunya, Japanese encephalitis, Zika and others claim millions of lives across the globe annually, and as such their control has become an ardent necessity. Past attempts over the decades have introduced vector control through chemical, biological and environmental means. However, these measures, already in place, failed to completely bring down the mortality rates from vector-borne diseases, most of which lack a vaccine to prevent epidemics or even a specific antidote to treat patients. The modern development of technologies such as the release of insects carrying a dominant lethal (RIDL) gene system, an example of transgenesis; the Wolbachia-based cytoplasmic incompatibility inducing infertility in female insects, an example of paratransgenesis; and the revolutionary gene drive (CRISPR/Cas9) technology, has their roots in the sterile insect technology (SIT), which worked by creating sterilized males through irradiation to compete with their wild counterparts and subsequently mate with females in nature to produce infertile eggs; a technology meant to gradually and finally exterminate the vector population in nature. These technologies have shown great promise, albeit many imperfections, particularly regarding acceptance by the concerned societies. As far as vector control is concerned, we have attempted to simplify their definitions for the common man so that the intricate scientific jargon about these technologies do not instill any fear or doubts to the end users.
Integrated Management of Malaria Vectors in Africa
19971R. Mbabazi, K. Maredia, B. B. El-Sayed, A. K. Babumba, M. Savadogo and O. Akinbo, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 11:36:56.
Malaria disease is a major public health burden in Africa. The control of malaria vectors is a critical component for prevention, management, and eradication of malaria disease. This chapter presents information on the current status of malaria vector control in Africa with emphasis on integrated vector management (IVM) programs. The chapter highlights innovative and emerging technologies such as sterile insect technique, gene drive, Wolbachia-based biological control, and other technologies for malaria vector control in Africa which can be integrated into IVM programs. The chapter also provides global resources on malaria vector management programs.
Engineering RNA Interference-Based Dengue Virus Resistance in the Mosquito Vector Aedes aegypti: The Current Status and Future Directions
19969S. D. Denipitiyage, Y. I. N. S. Gunawardene, Z. Federico and R. S. Dassanayake, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 11:32:49.
Dengue is an acute, febrile disease caused by the dengue viruses (DENV) comprising four serotypes and transmitted by the mosquito vector Ae. aegypti. DENV are single-stranded, positive-sense RNA viruses of the family Flaviviridae. Dengue is declared as a current significant challenge in the Southeast Asia, imposing growing burden on infected populations. To date, dengue control has mostly relied on vector control strategies which have largely become ineffective. There is, therefore, an urgent need for novel vector control strategies. Development of genetically modified mosquito vectors to manipulate disease-vectoring populations has gathered increased interest in recent time. RNAi-mediated viral resistance contributes to the suppression of viruses, including DENV in the mosquito vector Ae. aegypti. With recent advances in the field of molecular biology, we and other scientists are continuing to engineer genes that confer virus resistance to reduce transmission rates of DENV and introducing these genes into the mosquito genome. Even though scientists successfully generated mosquito refractory to DENV2–4, no mosquito refractory to all four serotypes has been developed to date. This limitation can be overcome by systematic analysis of the molecular mechanisms of RNAi in the mosquito vector Ae. aegypti. An enhanced understanding of RNAi function in the mosquito vector Ae. aegypti will facilitate the application of RNAi to control the transmission of the dengue disease in the future. Here, based on current understanding of the RNAi, we discuss the mechanisms of RNAi in the mosquito vector Ae. aegypti. We also provide guidelines for optimal design of RNAi experiments in Ae. aegypti with the possible risks associated with them along with proposed solutions.
Wolbachia: Biological Control Strategy Against Arboviral Diseases
19967I. Mohanty, A. Rath and R. K. Hazra, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 11:27:44.
Arboviral diseases like dengue, chikungunya, and Zika are among the major causes of mortality and morbidity in human population. The limited control methods together with lack of antiviral therapies and effective vaccines have paved way for new approaches. One such approach to reduce the ever alarming conflagration of vector-borne diseases is based on biological strategy that reduces or blocks pathogen transmission in the vector. In this context, Wolbachia, an endosymbiont in mosquitoes, is explored as a novel and ecofriendly control strategy. Wolbachia seems to confer resistance to diverse RNA viruses protecting lives from virus-induced mortality. This review envisages the deployment of Wolbachia technology in controlling several arboviral diseases.
Measuring Public Attitudes to Releases of Transgenic Mosquitoes for Disease Control, with Special Reference to Dengue and Malaria
19958L. A. De Las Llagas and M. S. T. Gunigundo, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 11:10:05.
Since the advent of DDT in public health and agriculture, science leaped forward with revolutionary technology such as gene drive or editing, thus making it possible to develop alternative approaches to address vector-borne diseases. However, their utilization and sustenance in public life are dependent on public attitude, i.e., societal awareness and social acceptance. In the face of strong skepticism against genetically modified organisms in both developed and developing countries, public acceptance is therefore a requirement (Boete and Beisel 2013, and Bohannon 2002, as cited in De Souza et al. Understanding the requirements and factors necessary for the acceptance of genetically modified mosquitoes as a potential malaria control tool in Ghana: a questionnaire survey, AsPac J Biol Biotechnol 21(3):76–88, 2013).
Experiences and Outcomes from a Worldwide Training Programme on Genetically Modified Vectors (GMVs) Related Biosafety for Human Health and the Environment
19956B. K. Tyagi, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 11:04:33.
Partial to virtual lack of any impact on control of vectors of human diseases, especially mosquitoes, warranted urgent search for new alternate technologies which will be safe, economical and environment-friendly, on one hand, and integrate with other tools and methodologies of the integrated vector management (IVM), on the other. Past few decades have witnessed surge of many effective and sustainable genetically and biotechnologically developed de novo technologies which tend to control mosquito vectors by working either to suppress (transgenesis) or replace (paratransgenesis), besides an array of other physiological interventions, on the vector populations. Several technologies such as, for example, Release of insect carrying Dominant Lethal (RIDL) gene system, Wolbachia (an endocellular symbiotic bacterium naturally present in many arthropods) induced cytoplasmic incompatibility (CI) resulting in unviable egg production and transforming dengue vectors (Aedes spp.) and malaria vectors (e.g., Anopheles stephensi) into resistant to respective pathogens, i.e., viruses and Plasmodium, have offered promise in controlling vector-borne diseases. Notwithstanding unchallengeable significance, these technologies have also raised many questions from both societies and governments of many countries. To alleviate their scepticism and other queries, many international organizations conducted meetings to generate consensus for guidelines, but even this helped marginally to pacify global interrogations. It was, therefore, considered opportune by the Tropical Disease Research (TDR)/WHO to set up a series of multi-regional training workshops in Africa (Bamako, Mali), Asia (Madurai, India) and Latin America (Medellin, Colombia) between 2008 and 2011 (WHO 2015). About 150 trainees were drawn from as diverse disciplines/walks of life as science, health departments, academics, social, legal, non-governmental organization. The outcome, inculcated from the experiences expressed by the trainees themselves post-workshops, has been very encouraging as they all found the training courses highly beneficial to comprehend genetically modified vectors/mosquitoes (GMV/GMM) related biosafety to the human and the environment and thus become a potential ambassador in their areas or countries to strongly communicate and advocate about the lasting benefits of the various genetically evolved technologies in the control of mosquitoes responsible for transmission of dengue and malaria, in particular.
Advances in Aedes Mosquito Vector Control Strategies Using CRISPR/Cas9
19929P. D. S. U. Wickramasinghe, G. N. Silva, Y. I. N. Silva Gunawardene and R. S. Dassanayake, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 09:39:52.
Advancements in genetic engineering have resulted in the development of mosquitoes with impaired vector competence, thereby limiting acquisition and transmission of pathogens. The main dengue (DENV) vector, Aedes aegypti, is an invasive species that have spread unwittingly across the world as a result of human trade and travel. The Ae. aegypti mosquito species has spread across tropical and subtropical regions, with higher presence in urban regions where rapid breeding patterns have shown in artificial containers. Identification of and treating an adequate number of mosquito breeding sites as a control measure have been done for the past couple of years, and yet improvement is far from the expectations, even with well-funded and well-organized initiatives. In order to stop the pathogen transmission, genetically modified mosquitoes (GMM) needs to be created and released. Despite many Aedes-related achievements, GMM creation has been challenging. The spread of particular genetic elements that impair vector competence, trigger deleterious recessive mutations, or skew a population's sex ratio can be used to prevent the spread of vector disease, or eradicate invasive organisms in a species-specific and eco-friendly manner. In recent years, genome editing strategies have evolved to make use of a variety of nucleases, ranging from sequence-specific zinc finger nucleases to modular TALENs (transcription activator-like effector nucleases) and most recently, RNA-guided nucleases adapted from bacterial adaptive immune systems, dubbed CRISPR/Cas (clustered regularly interspaced palindromic repeats/CRISPR associated systems). By combining these methods, a new era in gene editing had emerged. Generally, both of these gene editing technologies utilize sequence-specific nucleases to generate double-stranded DNA breaks (or nicks) in the target sequence, resulting in desired DNA modifications using endogenous DNA repair mechanisms. Since cells with DNA lesions are unable to divide further, the nuclease-generated strand breaks must be rapidly repaired by the cell to maintain the viability. CRISPR/Cas has been widely accepted for use in a variety of organisms, including insect species, with only minor optimization steps needed thus far. CRISPR/Cas9 technology transformed the process of engineering nucleases capable of cleaving complex genomic sequences. A complementary guide RNA (gRNA) directs the Cas9 endonuclease's operation to the specific DNA target site, enabling the editing of virtually any DNA sequence without complex protein engineering and selection procedures. Apart from genome editing, the specificity and flexibility of the CRISPR/Cas9 method enables unprecedented rapid development of genetically modified organisms with mutation systems for disease vector insect control. The stability and expression of the gene construct generated by CRISPR/Cas9 or any other method must be addressed before GMM are released, in order to make sure that pathogen transmission and formulation are interrupted robustly and completely. Spreading foreign antipathogen genes through gene drive strategies among wild mosquito populations strengthens the case for a more streamlined approach. Major fields that must be adequately assessed include risk evaluation and management, conducting studies to ensure human and environmental protection, developing effective control strategies built on comprehensive gene-driving systems, and adequately addressing the ethical, legal, and social consequences of GMM release. Although GMM is theoretically feasible as a disease control method, field releases should be made only when strong scientific evidence of human and environmental protection and effectiveness are presented, and public acceptance is addressed appropriately. This chapter discusses the diverse technological advances in generating Ae. aegypti mosquitoes which are resistant to dengue virus (DENV) and other diseases, as well as the biosafety and risk assessment of these procedures. Additionally, the chapter outlines a convincing path forward for developing successful genetic-based DENV control strategies based on CRISPR/Cas9, which could be expanded to control other arboviruses while maintaining biosafety.
Genetic Improvements to the Sterile Insect Technique (SIT) for the Control of Mosquito Population
19927P. V. D. Dilani, Y. I. N. S. Gunawardene and R. S. Dassanayake, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 09:33:58.
Mosquito-borne diseases are becoming a major health problem worldwide. At present, the principal method of controlling these diseases entirely depends on the mosquito vector control strategies. However, traditional control methods which are focussed on reducing mosquito populations through environmental management and the application of insecticides are largely ineffective. Hence, various control methods, including the release of sterile insect technique (SIT), have been proposed for the reduction of the mosquito population. As a species-specific control strategy, SIT offers considerable environmental benefits and a chemical-free option for insect control. However, the application of the SIT to mosquito control consistently suffered from lack of efficient sexing system, high fitness cost and operational difficulty in ionizing radiation, density-dependent nature of the target mosquito population and various other technical issues. The intervention of genetic engineering has led to several improvements in the operation or security of SIT programmes. The advent of mosquito transgenesis has paved the way for novel approaches in mosquito control. One possibility is a release of insects carrying dominant lethal (RIDL) strategy by engineering self-limiting gene, which offers solutions for many drawbacks of traditional SIT by providing genetic sterilization, genetic sexing, genetic containment and provision of genetic markers while maintaining its environmentally benign and species-specific utility. The success of this strategy often depends on how genetic modification affects the fitness of the mosquitoes. With several improvements and modifications allowing minimum fitness load, RIDL is now available for a wide range of mosquitoes such as Aedes aegypti, Aedes albopictus and Anopheles stephensi with field-testing possibilities. However, with solid epidemiological evidence and community support, widespread implementation of these strategies might reverse the current alarming global mosquito vector-borne diseases.
Arthropods of Medical Importance: Need for Genetic and Other Innovative Vector Control Technologies, with Emphasis on Eco-biosocial and Environmental Considerations.
19923B. K. Tyagi, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 09:22:08.
Among the world’s known vector groups, viz. arthropods, snails and rodents, the most important vectors originate from arthropods, the jointed legs. Arthropods are doubtlessly regarded as the most dominant creatures on the Earth due largely to their remarkable structural and behavioural diversity, besides humongous species preponderance. Of course, some of these arthropods are serious pests and/or vectors of human and animal diseases—deadly, debilitating and economy destructing. According to an estimate, arthropod species make approximately 80% of the global biological diversity. Born some 350–400 million years ago, they have of course achieved, to the utter envy of all other animal forms, a formidable genetic diversity and robustness so much so that they have virtually captivated pivotal human attention for centuries. They serve as a spectacular model of bioprospecting or laboratory experiments mostly because they are found in abundance, breed prodigiously and are exceptionally easier to culture or cultivate. For the aforesaid reasons, arthropods are also the easy target for genetic manipulations such as the transgenesis (using the release of insect carrying dominant lethal (RIDL) gene system or gene drive-based genome editing, e.g. CRISPR/Cas9, to suppress or replace the vector population) or paratransgenesis (e.g. deploying endosymbiont Wolbachia-induced cytoplasmic incompatibility for replacing natural vector population). In particular, the advent of CRISPR technology has excited the potential to engineer new game-changing technologies and innovative systems that can be used to control wild populations of mosquitoes. Two developments of particular interest are a self-limiting system termed precision-guided sterile insect technique (pgSIT) and a homing-based gene drive (HGD). The unique features of these systems can make them valuable tools to control vector mosquitoes in the future. All these biotechnological advancements in vector control are designed to fit well in the multi-methodical integrated vector management (IVM) strategy.
The Effects of Boric Acid Sugar Bait on Wolbachia Trans-Infected Male Aedes albopictus (ZAP Males®) in Laboratory Conditions
19917V. S. Aryaprema, W. A. Qualls, K. L. Dobson, S. L. Dobson and R.-D. Xue, Insects, 13. 2021-12-21 09:06:57.
The field release of Wolbachia trans-infected male mosquitoes, as well as the use of toxic sugar baits, is a novel and promising candidate technique for integrated mosquito management programs. However, the methods of action of the two techniques may not be complementary, because the Wolbachia method releases mosquitoes into the environment expecting a wild population reduction in subsequent generations while the toxic baits are intended to reduce the wild population by killing mosquitoes. This laboratory study was conducted to evaluate the effectiveness of boric acid toxic sugar baits on Wolbachia trans-infected male Aedes albopictus, relative to wild-type Ae. albopictus males. Wolbachia trans-infected (ZAP male®) and the wild-type Ae. albopictus males were exposed separately to 1% boric acid in a 10% sucrose solution in BugDorms. In the control test, the two groups were exposed to 10% sucrose solution without boric acid. Percent mortalities were counted for 24 h, 48 h and 72 h post exposure periods. The results show that 1% boric acid toxic sugar bait can effectively kill ZAP males under laboratory conditions, and the effectiveness was significantly higher after 24 h and 48 h, compared to wild-type male Ae. albopictus. This finding will help in planning and coordinating integrated mosquito management programs, including both Wolbachia trans-infected mosquito releases and the use of toxic sugar baits against Ae. albopictus.
Genetically Modified and other Innovative Vector Control Technologies
19912B. K. Tyagi, SpringerLink, 2021-12-21 08:48:19.
This book comprehensively covers the latest development in developing and deploying the genetically modified vectors, particularly Anopheles and Aedes mosquitoes responsible for transmitting malaria parasites and dengue viruses, the most deadly and/or debilitating among all the vector-borne diseases. It is considered timely and commensurate to bring about a book dealing with the various ecological, biological and social as well as regulatory aspects for the deployment of genetically modified vectors in special context with the biosafety of humans, his associates, and the environment. Written by an array of specialists and experts in various subjects of genetically modified organisms, this book centrally addresses the (i) basic principles of the genetic manipulation of vectors and they are potential impact on human and the environment, (ii) ecological, biological, ethical, legal and social implications of the use of genetically modified vectors, (iii) identification of potential hazards; assessment and management of risks for human and environment; risk/benefit analysis, (iv) principles and practices for the assessment and management of biosecurity and biosafety in laboratories (and in the field), (v) guiding principles for creation and management of institutional or national biosafety review boards and ethics review committees, and (vi) development and application of a biosafety regulatory framework and its related legal principles at national levels for securing the development and use of vector control methods based on genetic modification strategies.
Safe Application of Genetically Modified Mosquito (GMM) to Combat Dengue and Chikungunya Depends on Socioeconomic Status and Social Acceptance in the Developing Countries: A Comprehensive Analysis
19898M. N. Islam, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 08:16:32.
The emerging and re-emerging vector-borne diseases are a serious public health problem throughout the world. It has been observed that more than 100 countries and approximately half of the world’s population are at risk on vector-borne diseases (VBDs). The global burden of the vector-borne diseases is unacceptably high. It alludes toward their functional inappropriateness, untimeliness, and irrelevance in controlling vectors and vector-borne diseases. Modern technologies, coupled with other appropriate ones within the precincts of integrated vector management (IVM), can tide over this situation posed by conventional, mostly insecticide-based, methodologies. A lot of challenges, obstacles, and interruptive factors have warranted urgent deployment of new approaches for the control of VBDs keeping in mind the inbuilt ethical, social, and regulatory issues. Genetically modified mosquito (GMM) technology is a complex and highly sophisticated biotechnological intervention for suppression of vector populations. Wolbachia-associated sterile insect technique (SIT) has been proved highly significant and effective for replacement of mosquito populations. Adopting a highly sophisticated GMM technology to suppress or replace the mosquito populations’ density is a big question in developing countries because their priority is directed to foremost fulfill the basic human rights to sustain. Yet, notwithstanding foreseeable bottlenecks, of paramount importance is the need to deploy GMM technology with due consideration to socioeconomic factors and availability of advanced biotechnological facilities during the application of GMM in the developing countries.
Oxitec wraps mosquito trials for the season
19698T. O'Hara, Keynews.com, 2021-12-15 19:12:16.
The private bio-tech company Oxitec has wrapped up its test release of genetically modified mosquitoes in the Florida Keys
Genetic Control in Historical Perspective: The Legacy of India’s Genetic Control of Mosquitoes Unit
19652R. Wilbanks, Hastings Center Report, 51:S11-S18. 2021-12-14 18:54:15.
Abstract In the early 1970s, a World Health Organization-initiated and United States-funded project released lab-reared mosquitoes outside New Delhi in the first large-scale field trials of the genetic control of mosquitoes. Despite partnering with the Indian Council of Medical Research and investing significantly in outreach to local communities at the release sites, the project was embroiled in controversy and became an object of vehement debate within the Indian parliament and diplomatic contretemps between the United States and India. This early episode of genetic control research demonstrates how a scientific collaboration was entangled in geopolitics and shaped by the legacy of colonialism. This historical case study has implications for public deliberation in the present, pointing to the challenges of shared decision-making in the context of structural inequality, the way that a backdrop of military interest in a technology can impede trust, and the long-term consequences of projects that foster mistrust.
How Israelis help the world fight mosquito-borne diseases
19690A. K. Leichman, ISRAEL21c, 2021-12-14 18:22:37.
Israeli scientists and entrepreneurs understand the problems and risks and have been developing a series of ingenious remedies to this growing problem. Prof. Philippos Aris Papathanos, head of Hebrew University’s Insect Genetics Lab, was awarded a Bill & Melinda Gates Foundation grant to develop new genetic approaches for controlling malaria mosquito populations. “We’re building a modern variant of an old idea that has been around since the 1950s: to control mosquitoes by modifying and manipulating their genetics,” Papathanos tells ISRAEL21c. He explains that sterilizing and releasing individual male mosquitoes theoretically leads to the collapse of the population. But this tactic has proven difficult to upscale to the necessary level of a whole city, country or continent. Instead of sterilization, Papathanos’ lab is using cutting-edge CRISPR technology to modify male malaria mosquitoes’ Y chromosome so that they produce only male babies, and those sons inherit the altered chromosome. Over time, there will be no more females and hence no more disease-transmitting bites.“This method can suppress the population in a stronger way because the genes are designed to spread through the population. We don’t need to upscale if we make the system more efficient with the least number of insects released,” says Papathanos.
No, genetically engineered mosquitoes aren’t about to be released in Berkeley
19619K. D. Rauch, Berkeleyside, 2021-12-13 21:34:24.
Judith Pierce, public outreach coordinator for the Alameda County Mosquito Abatement District, would like to make one thing clear: A release of genetically engineered mosquitoes is not coming to Berkeley — or anywhere in Alameda County — in the near future. Not to her knowledge, anyway, and if it were official, she would know. The Berkeley City Council’s robust discussion of this at a council meeting in early November was based partially on misleading information, said Pierce.The council, at its Nov. 9 meeting, considered whether to send a letter to the Environmental Protection Agency (EPA) opposing a potential California pilot study of mosquitoes engineered to combat Zika, dengue, chikungunya, yellow fever and other diseases.Councilmember Ben Bartlett sponsored the item, sending out an email to constituents ahead of time urging them to take action to prevent the EPA from “releasing billions of genetically engineered mosquitoes across California, specifically in Alameda County.” The sample letter Bartlett presented to the council was focused statewide, but background information he shared, as well as discussion at the meeting, focused on keeping the mosquitoes out of the county.
In Real Life: GMOsquitoes
19544Newsy, 2021-12-06 20:41:41.
The release of genetically modified mosquitoes in Florida gives hope of reducing the spread of disease while causing concerns among some citizens.
Public Perceptions Regarding Genomic Technologies Applied to Breeding Farm Animals: A Qualitative Study
19920F. Z. Naab, D. Coles, E. Goddard and L. J. Frewer, BioTech, 10. 2021-12-03 09:13:38.
The societal acceptability of different applications of genomic technologies to animal production systems will determine whether their innovation trajectories will reach the commercialisation stage. Importantly, technological implementation and commercialisation trajectories, regulation, and policy development need to take account of public priorities and attitudes. More effective co-production practices will ensure the application of genomic technologies to animals aligns with public priorities and are acceptable to society. Consumer rejection of, and limited demand for, animal products developed using novel genomic technologies will determine whether they are integration into the food system. However, little is known about whether genomic technologies that accelerate breeding but do not introduce cross-species genetic changes are more acceptable to consumers than those that do. Five focus groups, held in the north east of England, were used to explore the perceptions of, and attitudes towards, the use of genomic technologies in breeding farm animals for the human food supply chain. Overall, study participants were more positive towards genomic technologies applied to promote animal welfare (e.g., improved disease resistance), environmental sustainability, and human health. Animal “disenhancement” was viewed negatively and increased food production alone was not perceived as a potential benefit. In comparison to gene editing, research participants were most negative about genetic modification and the application of gene drives, independent of the benefits delivered.
Applying functional genomics to the study of lamprey development and sea lamprey population control
19946J. R. York, R. E. Thresher and D. W. McCauley, Journal of Great Lakes Research, 47:S639-S649. 2021-12-01 09:30:24.
Lampreys are one of the few survivors of an ancient lineage of jawless vertebrates and have become an important study organism in numerous disciplines in the biological sciences, including evolutionary biology, embryology, ecology, physiology and biomedicine. At the same time, however, lampreys have created economic and ecological problems due, primarily, to the invasion of parasitic sea lamprey (Petromyzon marinus) into the North American Great Lakes and consequent negative impacts on local fish populations. Barriers, trapping and lampricide treatments have reduced these impacts, but concern for habitat restoration, non-target effects and possible evolution of resistance to lampricides suggests the need to develop additional strategies that supplement current control measures. The advent of functional genomics, and in particular CRISPR/Cas9 genome editing, offers a molecular approach to this on-going problem. Here, we review the successful application of functional genetic, transcriptomic, and CRISPR/Cas9 genome editing technologies in lampreys to address basic research questions in the fields of evolutionary and developmental biology. We then describe how these tools may be repurposed for use by fishery and conservation biologists to approach the problem of invasive sea lamprey from a molecular-genetic perspective.
New molecular genetic techniques: regulatory and societal considerations
19403Nielsen, K. M., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 18:07:46.
A rapidly expanding toolbox of techniques available for genome editing provides the basis for a new continuum in types of modifications that can be introduced into a genome and blur the bimodal GMO vs. non-GMO (genetically modified organism) divide. Site-directed nucleases (SDN) are now used to modify existing nucleotides within genomes instead of adding recombined DNA as transgenes. Moreover, new gene drive approaches are in development based on SDNs. A number of potential drive applications have been reported, but uncertainties in trait stability and limitations in knowledge of the affected system at various temporal and spatial levels slow down their current uses. Adoption of new genome targeted technology takes place in a social context. The context will vary between countries and cultures, expressed in values, ethics, politics and priorities - that are translated into different regulatory approaches. Some developed products using new genome editing techniques clearly fall under internationally negotiated regulations of GMOs. However, other product outcomes of editing techniques challenge our current understanding and definition of GMOs. There is an urgent need for further research, for building international consensus and harmonizing regulatory approaches to facilitate categorization, predictability, transparency, trust and trade.
Genome editing and its applications for insect pest control: Curse or blessing?
19401Hacker, I. , and Schetelig, M. F, AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 18:00:39.
Gene and genome editing are described as cutting-edge research tools with the potential to tackle urgent global challenges in the management of agricultural pests and human disease vectors such as mosquitoes. The field is defined by the chances and challenges to interlink the disciplines of insect genomics, molecular biology, and pest control together with the need for clear risk assessment, policy development and public approval of the application of such novel technologies. The goal is to generate innovative and sustainable pest control solutions applied in the best interest for the environment and human society. Here, starting from available genome editing technologies, the current strategies and applications for insect pest control are discussed, including approaches to overcome the evolution of resistance alleles and other potential pitfalls to be expected from selective pressures resulting from gene drive applications. They are supplemented by views on regulatory, policy and ethical considerations that in our opinion will be necessary to define how the different tools can be used in the future in a safe and responsible way.
Barriers and facilitators of area-wide management including sterile insect technique application: The example of Queensland fruit fly
19365Mankad, A., Loechel, B., and Measham, P. F., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 16:44:16.
The area-wide management (AWM) of highly mobile insect pests such as tephritid fruit flies requires an integrated understanding of technical, social and institutional processes that drive a coordinated approach within a defined area. Furthermore, the success of an AWM programme is dependent upon the coordinated efforts of key stakeholders within the designated area (e.g. growers, community members). Yet, public views regarding AWM may not reflect those views held by scientists or stakeholders. Public considerations for acceptance are likely varied and multidimensional. A series of qualitative (phases 1-2) and quantitative (phase 3) studies examined stakeholder and community attitudes towards AWM to manage Queensland fruit fly Bactrocera tryoni (Froggatt) (Tephritidae) and the novel use of the Sterile Insect Technique (SIT) as a possible component of AWM. Research was conducted over three regions of varying pest prevalence, ranging from zero to endemic; participants included growers, extension officers, industry and government representatives, and members of the general public. Participants in this research were asked to consider potential barriers and facilitators to the widespread uptake of AWM integrating the SIT, including any relevant institutional-level factors. Combined data revealed potential social barriers to AWM and SIT uptake. Most notably, there were perceptions of low efficacy in successfully coordinating key social groups for the purposes of an AW-IPM approach, and a concern for the possibility of 'free-riders' within an areawide system. On the other hand, innovation complexity and observability of outcomes were important factors contributing to acceptance of AWM. Importantly, all participants were influenced by the attitudes and behaviours of important others. Participants also identified key facilitators that could assist in the uptake of AWM using the SIT. These facilitators include the importance of trustworthy information sources and harnessing the persuasive influence of community champions and central packing houses on commercial growers. Overall, there was high stated acceptance for the SIT, both on-farm and in towns, as long as SIT application was found to be economically feasible at individual farm or household level and the community was adequately consulted.
The suppression of the False Codling Moth in South Africa using an AW-IPM approach with a SIT component
25890N. Boersma, AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 10:26:27.
The false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is native to subSaharan Africa, where it infests various commercial, and wild, fruit-bearing plants. This major pest is not present in the Americas, Europe, and Asia, and therefore has phytosanitary implications, which impose severe limitations on potential South African exports. Consequently, this pest represents a severe threat to the fruit industry of South Africa, in terms of socio-economic impacts on both fruit production and job security. Although the pest can be managed to some extent with insecticides, mating disruption, and orchard sanitation, a long-term environment-friendly solution was needed. This became more evident as T. leucotreta developed resistance to available insecticides, while stricter quarantine measures were enforced by importers of African citrus. In 2002, research commenced on an area-wide integrated pest management (AW-IPM) programme in conjunction with the development of the Sterile Insect Technique (SIT) for the false codling moth. Commercial sterile insect releases started in the 2007-2008 season over 1500 ha of citrus orchards in Citrusdal, Western Cape Province, but by 2017-2018 had gradually expanded to almost 19 000 ha in three different citrus producing regions of South Africa. The programme is currently owned by the Citrus Growers Association (CGA) that have contributed to the steady growth of the SIT programme in the citrus industry. Over the past ten years the status of T. leucotreta as a pest threat was systematically reduced in areas where the SIT was practiced on an area-wide basis, compared to non-release areas.
Wolbachia reduces virus infection in a natural population of Drosophila
19437R. Cogni, S. D. Ding, A. C. Pimentel, J. P. Day and F. M. Jiggins, Communications Biology, 4:1327. 2021-11-25 20:42:30.
Wolbachia is a maternally transmitted bacterial symbiont that is estimated to infect approximately half of arthropod species. In the laboratory it can increase the resistance of insects to viral infection, but its effect on viruses in nature is unknown. Here we report that in a natural population of Drosophila melanogaster, individuals that are infected with Wolbachia are less likely to be infected by viruses. By characterising the virome by metagenomic sequencing and then testing individual flies for infection, we found the protective effect of Wolbachia was virus-specific, with the prevalence of infection being up to 15% greater in Wolbachia-free flies. The antiviral effects of Wolbachia may contribute to its extraordinary ecological success, and in nature the symbiont may be an important component of the antiviral defences of insects.
Historical perspective and new avenues to control the myiasis-causing fly Cochliomyia hominivorax in Uruguay.
23386Fresia P, Pimentel S, Iriarte V, Marques L, Durán V, Saravia A, Novas R, Basika T, Ferenczi A, Castells D, Saporiti T, Cuore U, Losiewicz S, Fernández F, Ciappesoni G, Dalla-Rizza M and M. A., Agrociencia Uruguay, 25:e974. 2021-11-18 07:43:36.
Mosca de la bichera’ or simply ‘bichera’ are common names given in Uruguay and the region to the primary myiasis-causing species Cochliomyia hominivorax, the New World Screwworm (NWS) fly (Diptera: Calliphoridae). Myiasis happens when dipteran larvae infest live animals at least during some developmental phase to feed on host’s flesh and fluids. For the NWS fly it is mandatory that all three larvae phases develop on living tissues of warm-blooded vertebrates, including humans. Unsurprisingly, this parasitic behavior causes great profit losses to the livestock industry and is also considered a neglected public health issue. NWS is endemic from the tropics and subtropics of the Americas, but has been eradicated from North and Central America through a Sterile Insect Technique (SIT) based Area Wide – Integrated Pest Management (AW-IPM) program that lasted more than 50 years
Science Has Given Us the Power to Undermine Nature’s Deadliest Creature: Should We Use It?
19304E. Herold, leaps.org, 2021-11-16 13:32:15.
British biotech company Oxitec has engineered male mosquitoes to have a genetic "kill-switch" that could potentially crash the local population of Aedes aegypti, at least in the short-term. The modified males that are being released are intended to mate with wild females. Males don't bite; it's the female that's deadly, always seeking out blood to gorge on to help mature her eggs. After settling her filament-thin legs on her prey, she sinks a needlelike proboscis into the skin and sucks the blood until her translucent belly is bloated and glowing red. The kill-switch will ensure that the female offspring die before they reach maturity and thus, be unable to reproduce. Should a small number of them survive, they will be rendered unable to bite. The genetic modification means the proboscis, the sickle-like needle that pierces the skin, won't form properly. The idea is that the lack of females for the males to mate with, over a few generations, will collapse the local population of Aedes aegypti. The modified mosquitoes are the second genetically engineered insect to be released in the U.S. by Oxitec. The first was a modified diamondback moth, an agricultural pest that doesn't bite humans. But with the mosquitoes, there are many questions about the long-term effects on wild ecosystems, other species in the food chain, and human health. With the Keys initiative, there has been vociferous opposition from environmental groups and some local residents, but some scientists and public health experts say that genetically modified insects pose less of a risk than the diseases they carry and the powerful, indiscriminant pesticides used to combat them.
A Household-Based Survey to Understand Factors Influencing Awareness, Attitudes and Knowledge towards Wolbachia-Aedes Technology
19435L. T. Soh, Z. Ong, K. Vasquez, I. Chen, X. Li, W. Niah, C. Panchapakesan, A. Sheldenkar, S. Sim, L. C. Ng and M. O. Lwin, International Journal of Environmental Research and Public Health, 18. 2021-11-15 20:37:00.
In 2016, Singapore introduced the release of male Wolbachia-Aedes mosquitoes to complement vector control efforts and suppress Aedes aegypti mosquitoes in selected study sites. With ongoing expansion of Project Wolbachia-Singapore to cover larger areas, a household-based survey was conducted between July 2019 to February 2020 in two Project Wolbachia study sites using a structured questionnaire, to evaluate current sentiments and assess the need for enhanced public messaging and engagement. The association of factors that influence awareness, attitudes, and knowledge towards the use of Wolbachia-Aedes technology was analysed using Pearson's Chi-square test and binary logistic regression. Of 500 respondents, 74.8% were aware of Project Wolbachia-Singapore. Comparatively, the level of knowledge on Wolbachia-Aedes technology was lower, suggesting knowledge gaps that require enhanced communication and messaging to address misinformation. Longer exposure to the project predicted greater awareness, whereas higher education levels predicted higher knowledge levels. Younger age groups and higher education levels were associated with high acceptance towards the project. High levels of trust and acceptance towards the project were also observed across the population. The public's positive perception of the project is a testament to the effective public communication undertaken to date and will facilitate programme expansion.
Gene drives in malaria control: what we need to know
19289R. Mudziwapasi, M. C. Changara, A. Ndudzo, T. Kaseke, F. Godobo, F. L. Mtemeli, R. Shoko, F. Songwe, S. Ndlovu and S. Sandra Mlambo, Biotechnology and Biotechnological Equipment, 35:1623-1631. 2021-11-15 13:42:40.
Gene drives are being used to enhance a DNA sequence?s likelihood of passing between generations via sexual reproduction. Gene drives can be deployed to manipulate natural populations. They can be used to suppress populations by reducing the number of individuals in a population or to modify populations. There are more than 3000 mosquito species in the world, some of which are vectors of diseases. Malaria is a typical disease whose vectors are mosquitoes. It affects mostly tropical countries. It kills many people annually, many of whom are children. Interventions currently in use, such as indoor residual spraying and mosquito nets, are proving insufficient to eradicate malaria. Gene drives can be used in different ways to control mosquito populations or to eliminate mosquito species, thereby reducing malaria cases and deaths. This can occur through population replacement or suppression. However, before the elimination of any mosquito species for malaria control, it is necessary to consider the effects of such an action. Additionally, there is a need to review the options available for the control of mosquitoes and to create awareness of the benefits and risks of such an action. This paper, therefore, looks at the role of mosquitoes in the environment, the methods of controlling mosquitoes and malaria and necessary considerations when using gene drives inter alia.
New developments in the field of genomic technologies and their relevance to conservation management
19273G. Segelbacher, M. Bosse, P. Burger, P. Galbusera, J. A. Godoy, P. Helsen, C. Hvilsom, L. Iacolina, A. Kahric, C. Manfrin, M. Nonic, D. Thizy, I. Tsvetkov, N. Veličković, C. Vilà, S. M. Wisely and E. Buzan, Conservation Genetics, 2021-11-11 16:22:03.
Recent technological advances in the field of genomics offer conservation managers and practitioners new tools to explore for conservation applications. Many of these tools are well developed and used by other life science fields, while others are still in development. Considering these technological possibilities, choosing the right tool(s) from the toolbox is crucial and can pose a challenging task. With this in mind, we strive to inspire, inform and illuminate managers and practitioners on how conservation efforts can benefit from the current genomic and biotechnological revolution. With inspirational case studies we show how new technologies can help resolve some of the main conservation challenges, while also informing how implementable the different technologies are. We here focus specifically on small population management, highlight the potential for genetic rescue, and discuss the opportunities in the field of gene editing to help with adaptation to changing environments. In addition, we delineate potential applications of gene drives for controlling invasive species. We illuminate that the genomic toolbox offers added benefit to conservation efforts, but also comes with limitations for the use of these novel emerging techniques.
Genetic control of invasive sea lamprey in the Great Lakes
19270D. Ferreira-Martins, J. Champer, D. W. McCauley, Z. Zhang and M. F. Docker, Journal of Great Lakes Research, 2021-11-08 16:16:20.
The invasive sea lamprey was a significant factor in the collapse of fish stocks in the Great Lakes, and it continues to threaten the multi-billion-dollar fishing industry. Thus, substantial resources are invested annually on sea lamprey control. Current control strategies have reduced sea lamprey populations by up to 90%, but they are expensive and have some limitations, e.g., lamprey-specific biocides applied to larval habitat impact native lampreys, and physical barriers that block adult lamprey access to spawning habitat impede migration of other fishes. Therefore, genetic control options which offer a theoretically powerful and effective pest control tool are being explored, although they have uncertain sociopolitical support, especially given the need to protect sea lamprey in their native range in Atlantic drainages. Here, we present an overview of genetic approaches with potential for application to sea lamprey control in the Great Lakes. We classify these approaches into two major categories: self-limiting (heritable sex ratio ratchet, Trojan gene, split gene drive) and self-sustaining (gene drive-based sex ratio distortion, homing suppression gene drive, toxin-antidote gene drives, and modification-type gene drives to aid suppression). We describe the technical aspects, challenges, and potential application of each method, focusing on gene drives, a fast-evolving research area that was only a distant option for sea lamprey control in previous reviews. We conclude that, given the risk of undesired spread of deleterious alleles from the Great Lakes, self-limiting genetic control options and confined gene drives will likely be preferred over unconfined gene drive options for sea lamprey control.
Malaria modeling and optimal control using sterile insect technique and insecticide-treated net
19230L. Cai, L. Bao, L. Rose, J. Summers and W. Ding, Applicable Analysis, 2021-11-05 21:55:36.
We investigate a malaria transmission model with SEIR (susceptible-exposed-infected-recovered) classes for the human population, SEI (susceptible-exposed-infected) classes for the wild mosquitoes and an additional class for the sterile mosquitoes. The basic reproduction number of the disease transmission is obtained, and a release threshold of the sterile mosquitoes is provided. We formulate an optimal control problem in which the goal is to minimize both the infected human populations and the cost to implement two control strategies: the release of sterile mosquitoes and the usage of insecticide-treated nets to reduce the malaria transmission. Adjoint equations are derived, and the characterization of the optimal controls is established. Finally, we quantify the effectiveness of the two interventions aimed at limiting the spread of malaria transmission. A combination of both strategies leads to more rapid elimination of the wild mosquito population that can suppress malaria transmission. Numerical simulations are provided to illustrate the results.
Will freeing ourselves (forever) from mosquitoes soon be a realizable “dream”? Pros and cons of an epochal turning point – breaking latest news
19160Annonymous, Breaking Latest News, 2021-11-05 14:34:10.
Also true for a dangerous insect like the mosquito: due to the pathologies of which vector, such as the malaria, the dengue o la yellow fever, every year in the world about 800 thousand people die. There are therefore quite a few reasons to want to get rid of it, not just the itchy summer bites, and thanks to the technique developed by Professor Crisanti it would seem possible, in a not too distant future. It starts from a premise: Not that we want to get rid of all mosquitoes. There are around 3,500 species of mosquitoes and fortunately only a few transmit parasitic diseases such as malaria or others that cause diseases such as zika and dengue. So if I want to get rid of malaria I have to attack malaria. Traditionally this has been done with insecticides which have shown all their limits and dangers. These measures, which are apparently simple, require sustainability over time, require resources and political continuity. All this is missing today. Hence biotechnology, the idea of making mosquitoes themselves do this job. If we manage to modify the genetic characteristics of mosquitoes, we can theoretically create mosquitoes that do not reproduce or that do not transmit the infection.
Oxitec Announces Ground-breaking Commercial Launch of Its Friendly™ Aedes aegypti Solution in Brazil
19395Oxitec, COSION, 2021-11-03 17:40:43.
Oxitec, the leading developer of biological solutions to control pests, announced today the landmark commercial launch of its Friendly™ Aedes aegypti solution designed specifically for use by homeowners, businesses, and communities to control the dengue-spreading Aedes aegypti mosquito. This launch represents the first time globally that the benefits of using biologically engineered mosquito control technology that can be purchased directly by consumers. Having received full biosafety commercial approval in 2020 from the Brazilian government's biosafety authority, CTNBio, the company is making its just-add-water solution available for delivery directly to customers' doorsteps starting in the State of São Paulo. Available for purchase online, the product comprises durable outer boxes and Friendly™ male mosquito egg refill packs. Once delivered, customers need only to add water to the Friendly™ box, place it in a garden, patio, or around a home or business, and the boxes will produce Oxitec's non-biting male mosquitoes over time, which disperse to find and mate with invasive, biting Aedes aegypti females. Their female offspring cannot survive, which means fewer biting female mosquitoes in the following generations. While the Friendly™ Aedes aegypti males pursue and mate with female Aedes aegypti, customers need only reactivate the easy-to-use box once per month. This technology controls the pest without harming beneficial species like bees and butterflies and does not persist in the environment.
Fighting Dengue Virus with Biological Weapons
19130Z. Ebrahim, Inter Press Service, 2021-11-02 14:34:03.
For the last 11 years, he has been trying to convince both the provincial and central governments of making “billions of mosquitoes in labs”, which when released in the wild, could reduce the spread of dengue virus, but with little luck. The released genetically engineered male (only) mosquitoes, when they mate with Aedes females (also the carrier of the virus), would produce offspring that would die while still at larvae or pupae stage, explained Ali, the only Pakistani with a doctorate in genetically modified mosquitoes. In addition, genetic modifications, he said, can also shorten the life span, cause sterility and even death of the transformed Aedes species. However, those who can decide have dawdled for too long with the result that the virus has gone out of control, he remarked. He has been trying to draw attention but with little success. “They [government officials] tell me if word gets out the government was fighting the virus by letting loose even more mosquitoes, they will have to confront the wrath of the public!”
Conditional knockdown of transformer in sheep blow fly suggests a role in repression of dosage compensation and potential for population suppression
19004M. E. Williamson, Y. Yan and M. J. Scott, PLOS Genetics, 17:e1009792. 2021-10-18 15:15:17.
In the fruit fly Drosophila melanogaster and in the mosquito Anopheles gambiae, a single gene (Sxl in D. melanogaster, fle in A. gambiae) controls the development of female-specific tissues and X chromosome dosage compensation, which is the equalization of X-linked gene products in males and females. In this study we find evidence that the transformer gene is essential for somatic sex differentiation and repression of X chromosome dosage compensation in female sheep blow fly, Lucilia cuprina. In several of the transgenic strains developed, females are transformed into males on diet that lacks tetracycline. Consequently, these strains could be part of a genetic control program of this major pest of sheep in Australia.
Sterilizing Male Mosquitoes with Gene Editing to Reduce Disease Spread
18938Global Biodefense Staff, Global Biodefense, 2021-10-11 20:42:18.
Researchers at the Army’s Institute for Collaborative Biotechnologies and the University of California Santa Barbara used a gene editing tool known as CRISPR-Cas9 to target a specific gene tied to fertility in male mosquitoes. Researchers experimented with the Aedes aegypti mosquitoes, which are found in tropical, subtropical and temperate regions throughout the world. The study, published in the Proceedings of the National Academy of Sciences, discerned how a mutation can suppress the fertility of female mosquitoes. To manage populations, scientists use a vector-control practice called the sterile insect technique in which they raise a lot of sterile male insects and they then release these males in numbers that overwhelm their wild counterparts. Females that mate with sterile males before finding a fertile one are themselves rendered infertile, thereby decreasing the size of the next generation. Repeating this technique several times has the potential to crash the population because each generation is smaller than the last; releasing a similar number of sterile males has a stronger effect over time.
Trial suppresses mosquitoes using non-GMO approach
18863GM Watch, GM Watch, 2021-10-07 18:51:46.
In a first for the Southern Hemisphere, researchers have shown that a bacterium can successfully suppress populations of the invasive, disease-carrying Aedes aegypti mosquito that is responsible for spreading dengue, yellow fever and Zika. Published in PNAS (see abstract below), the trial involved releasing three million male Aedes aegypti mosquitoes in Northern Queensland, sterilised with a naturally occurring bacterium called Wolbachia, across three trial sites over a 20-week period during the summer of 2018. The sterile male insects search out and mate with wild females, preventing the production of offspring. Scientists returned the following year and found one of the trial sites, Mourilyan in Queensland, was almost devoid of mosquitoes.
Genome engineering in insects for the control of vector borne diseases
18875V. E. Hillary and S. A. Ceasar, Progress in Molecular Biology and Translational Science, 179:197-223. 2021-10-05 19:22:57.
Insects cause many vector-borne infectious diseases and have become a major threat to human health. Although many control measures are undertaken, some insects are resistant to it, exacerbated by environmental changes which is a major challenge for control measures. Genetic studies by targeting the genomes of insects may offer an alternative strategy. Developments with novel genome engineering technologies have stretched our ability to target and modify any genomic sequence in Eukaryotes including insects. Genome engineering tools such as zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and most recently discovered, clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (Cas9) systems hold the potential to control the vector-borne diseases. In this chapter, we review the vector control strategy undertaken by employing three major genome engineering tools (ZFNs, TALENs, and CRISPR/Cas9) and discuss the future prospects of this system to control insect vectors. Finally, we also discuss the CRISPR-based gene drive system and its concerns due to ecological impacts.
Invasive, disease-carrying Aedes aegypti mosquito sterilized with bacteria and eradicated in large-scale trial
18872CSIRO, Phys Org, 2021-10-05 19:15:01.
In a first for the Southern Hemisphere, researchers have shown a bacteria can successfully sterilize and eradicate the invasive, disease carrying Aedes aegypti mosquito which is responsible for spreading dengue, yellow fever and Zika. The breakthrough could support the suppression and potential eradication of Aedes aegypti worldwide. Published today in PNAS, the landmark trial involved releasing 3 million male Aedes aegypti mosquitoes in Northern Queensland sterilized with bacteria called Wolbachia. The trial was conducted across three sites over a 20-week period during the summer of 2018. The sterile male insects search out and mate with wild females, preventing the production of offspring.
Releasing incompatible males drives strong suppression across populations of wild and Wolbachiat-carrying Aedes aegypti in Australia
18844N. W. Beebe, D. Pagendam, B. J. Trewin, A. Boomer, M. Bradford, A. Ford, C. Liddington, A. Bondarenco, P. J. De Barro, J. Gilchrist, C. Paton, K. M. Staunton, B. Johnson, A. J. Maynard, G. J. Devine, L. E. Hugo, G. Rasic, H. Cook, P. Massaro, N. Snoad, J., Proceedings of the National Academy of Sciences, 118:e2106828118. 2021-10-05 11:33:10.
Through replicated treatment and control experiments in northern Australia, regular releases of Aedes aegypti males infected with a Wolbachia from Aedes albopictus was shown to drive strong population suppression in mosaic populations of wild-type (no Wolbachia) and wMel-Wolbachia–carrying Ae. aegypti. In a demonstration of bidirectional incompatibility between different Wolbachia strains in the field, we also demonstrate that one season’s suppression experiment can also show an ongoing effect into the following season.Releasing sterile or incompatible male insects is a proven method of population management in agricultural systems with the potential to revolutionize mosquito control. Through a collaborative venture with the “Debug” Verily Life Sciences team, we assessed the incompatible insect technique (IIT) with the mosquito vector Aedes aegypti in northern Australia in a replicated treatment control field trial. Backcrossing a US strain of Ae. aegypti carrying Wolbachia wAlbB from Aedes albopictus with a local strain, we generated a wAlbB2-F4 strain incompatible with both the wild-type (no Wolbachia) and wMel-Wolbachia Ae. aegypti now extant in North Queensland. The wAlbB2-F4 strain was manually mass reared with males separated from females using Verily sex-sorting technologies to obtain no detectable female contamination in the field. With community consent, we delivered a total of three million IIT males into three isolated landscapes of over 200 houses each, releasing ∼50 males per house three times a week over 20 wk. Detecting initial overflooding ratios of between 5:1 and 10:1, strong population declines well beyond 80% were detected across all treatment landscapes when compared to controls. Monitoring through the following season to observe the ongoing effect saw one treatment landscape devoid of adult Ae. aegypti early in the season. A second landscape showed reduced adults, and the third recovered fully. These encouraging results in suppressing both wild-type and wMel-Ae. aegypti confirms the utility of bidirectional incompatibility in the field setting, show the IIT to be robust, and indicate that the removal of this arbovirus vector from human-occupied landscapes may be achievable
Investigation of Developmental Stage/Age, Gamma Irradiation Dose, and Temperature in Sterilization of Male Aedes aegypti (Diptera: Culicidae) in a Sterile Insect Technique Program
20236B. Ernawan, T. Anggraeni, S. Yusmalinar and I. Ahmad, Journal of Medical Entomology, 59:320-327. 2021-10-01 09:18:43.
The sterilization process using gamma irradiation is a crucial component in a program using sterile insect technique (SIT) to control Aedes aegypti. Unfortunately, there is no efficient standard protocol for sterilizing mosquitoes that can produce a high level of sterility while maintaining mating ability and longevity. Therefore, we conducted a study of the critical factors necessary to develop such a standard protocol. In this study, male Ae. aegypti pupae, as well as adults aged 1 d and 3 d, were irradiated using a Gamma-cell 220 irradiator doses of 0, 20, 40, 60, 70, 80, and 100 Gray (Gy). In addition, male Ae. aegypti in the pupal and adult stage aged 1 d were irradiated at a dose of 70 Gy at various temperatures. Changes in emergence rates, longevity, sterility, and mating competitiveness were recorded for each combination of parameters. Results showed that an in-crease of irradiation dose leads to a rise of induced sterility at all developmental stages, while simultaneously reducing emergence rate, survival, and mating competitiveness. Higher temperatures resulted in increased levels of sterility, reduced longevity, and did not affect the ability to mate. This study found that an irradiation dose of 70 Gy at a temperature between 20.00 and 22.30°C administered in the pupal stage induced a high level of sterility (around 98%), while maintaining mating competitiveness and longevity
Plan for California’s Genetically Modified Mosquitoes Draws Fire
18813T. Baltz, Bloomberg Law, 2021-09-29 15:13:31.
A U.K.-based biotech company’s proposal to release genetically engineered mosquitoes in California as a disease-control measure is prompting criticism that the program could create unnatural consequences. Oxitec says it would unleash safe, non-biting male mosquitoes to reduce the population of mosquitoes that spread dengue, Zika, yellow fever, and other diseases. It applied in August for an Environmental Protection Agency permit to release the genetically modified organisms, or GMOs, for pilot projects in the state. Opponents say the company’s plan lacks rigorous assessments of potentially serious health and environmental impacts, and could have “disastrous consequences” in the U.S. and other countries. ...
Genetically-modified possums and all-in-one trapping machines: funding for new predator-free studies
18787A. Allott, stuff, 2021-09-24 13:32:23.
Research into possum genes and creating an all-in-one predator detecting, luring, and trapping machine are among a handful of projects to receive new funding to help bring them into reality. Predator Free 2050 has awarded $2.4 million in Jobs for Nature funding to six postgraduate and post-doctoral researchers from Otago, Canterbury, Lincoln and Auckland universities. University of Otago researcher Alana Alexander, who is trying to discover which genes are important for possums’ reproduction and survival, is one of them. “Gene drives seem very exciting, but they’re a genie in a bottle. We don’t really want possums in New Zealand, but they are part of the ecosystem in Australia, so making sure it’s contained would be really important.” Alexander said she wants people to understand the risks and benefits, so they can give informed consent when thinking about pest control down the line.
A single mutation weakens symbiont-induced reproductive manipulation through reductions in deubiquitylation efficiency
18742J. F. Beckmann, K. Van Vaerenberghe, D. E. Akwa and B. S. Cooper, Proceedings of the National Academy of Sciences, 118:e2113271118. 2021-09-21 14:01:04.
We show that a single naturally observed mutation weakens CI by reducing deubiquitylation. These discoveries help elucidate the molecular basis of symbiont-induced reproductive manipulations.Animals interact with microbes that affect their performance and fitness, including endosymbionts that reside inside their cells. Maternally transmitted Wolbachia bacteria are the most common known endosymbionts, in large part because of their manipulation of host reproduction. For example, many Wolbachia cause cytoplasmic incompatibility (CI) that reduces host embryonic viability when Wolbachia-modified sperm fertilize uninfected eggs. Operons termed cifs control CI, and a single factor (cifA) rescues it, providing Wolbachia-infected females a fitness advantage. Despite CI’s prevalence in nature, theory indicates that natural selection does not act to maintain CI, which varies widely in strength. Here, we investigate the genetic and functional basis of CI-strength variation observed among sister Wolbachia that infect Drosophila melanogaster subgroup hosts. We cloned, Sanger sequenced, and expressed cif repertoires from weak CI–causing wYak in Drosophila yakuba, revealing mutations suspected to weaken CI relative to model wMel in D. melanogaster. A single valine-to-leucine mutation within the deubiquitylating (DUB) domain of the wYak cifB homolog (cidB) ablates a CI-like phenotype in yeast. The same mutation reduces both DUB efficiency in vitro and transgenic CI strength in the fly, each by about twofold. Our results map hypomorphic transgenic CI to reduced DUB activity and indicate that deubiquitylation is central to CI induction in cid systems. We also characterize effects of other genetic variation distinguishing wMel-like cifs. Importantly, CI strength determines Wolbachia prevalence in natural systems and directly influences the efficacy of Wolbachia biocontrol strategies in transinfected mosquito systems. These approaches rely on strong CI to reduce human disease.All study data are included in the article and/or supporting information.
Discrete dynamical models on Wolbachia infection frequency in mosquito populations with biased release ratios
18717Y. Shi and B. Zheng, Journal of Biological Dynamics, 2021-09-18 14:11:29.
We develop two discrete models to study how supplemental releases affect the Wolbachia spreading dynamics in cage mosquito populations. The first model focuses on the case when only infected males are released at each generation. This release strategy has been proved to be capable of speeding up the Wolbachia persistence by suppressing the compatible matings between uninfected individuals. The second model targets the case when only infected females are released at each generation. For both models, detailed model formulation, enumeration of the positive equilibria and their stability analysis are provided. Theoretical results show that the two models can generate bistable dynamics when there are three positive equilibrium points, semi-stable dynamics for the case of two positive equilibrium points. And when the positive equilibrium point is unique, it is globally asymptotically stable. Some numerical simulations are offered to get helpful implications on the design of the release strategy.
Malaria and the future of mosquito control
18712E. Gonzalez Fernandez, CATALYST, 2021-09-18 14:01:52.
Focusing on mosquito population control, new strategies based on genetic approaches have emerged with the premise of being more eco-friendly. The aim is to not harm the environment or affect other animals since they will only target a specific mosquito species. Genetic control strategies depend on the introduction of an inheritable trait into the wild type population. There are two main outcomes, the suppression, or the replacement of the insect population. In the first one, the new trait leads to a reduction of their population. In the second one, the existing mosquito population is replaced with mosquitoes that have the new characteristic, making the mosquito, for example, unable to transmit the pathogen (refractoriness), the latter doesn’t reduce the number of mosquitoes in the area. The discovery of CRISPR/Cas9, recently awarded the Nobel Prize, has opened an incredible path in genetics and is the fundamental pillar for the new strategies under development for mosquito control. Specifically, the so-called gene drive systems benefit from the CRISPR/Cas9 technology. These gene drive systems aim to spread the new trait into the population in a super-Mendelian way. It means that the gene drive encourages unbalanced inheritance in favour of the new trait, so the new trait is passed on to off-spring so the new would make the ‘old’ disappear in a short period of time. And, as previously mentioned, these could be by reducing or replacing
Symbiotic Interactions Between Mosquitoes and Mosquito Viruses
18715M. Altinli, E. Schnettler and M. Sicard, Front Cell Infect Microbiol, 11:694020. 2021-09-17 14:06:45.
Mosquitoes not only transmit human and veterinary pathogens called arboviruses (arthropod-borne viruses) but also harbor mosquito-associated insect-specific viruses (mosquito viruses) that cannot infect vertebrates. In the past, studies investigating mosquito viruses mainly focused on highly pathogenic interactions that were easier to detect than those without visible symptoms. However, the recent advances in viral metagenomics have highlighted the abundance and diversity of viruses which do not generate mass mortality in host populations. Over the last decade, this has facilitated the rapid growth of virus discovery in mosquitoes. The circumstances around the discovery of mosquito viruses greatly affected how they have been studied so far. While earlier research mainly focused on the pathogenesis caused by DNA and some double-stranded RNA viruses during larval stages, more recently discovered single-stranded RNA mosquito viruses were heavily studied for their putative interference with arboviruses in female adults. Thus, many aspects of mosquito virus interactions with their hosts and host-microbiota are still unknown. In this context, considering mosquito viruses as endosymbionts can help to identify novel research areas, in particular in relation to their long-term interactions with their hosts (e.g. relationships during all life stages, the stability of the associations at evolutionary scales, transmission routes and virulence evolution) and the possible context-dependent range of interactions (i.e. beneficial to antagonistic). Here, we review the symbiotic interactions of mosquito viruses considering different aspects of their ecology, such as transmission, host specificity, host immune system and interactions with other symbionts within the host cellular arena. Finally, we highlight related research gaps in mosquito virus research.
Scientists use gene editing tool to target mosquito-spread disease
18650Medical Research Council, Phys Org, 2021-09-13 20:12:56.
Advances in genome editing have allowed the development of genetic insect control methods, which could be highly effective and are species-specific. The results have been published in Scientific Reports. Scientists showed that a method involving a gene editing tool called CRISPR/Cas9 could be used to successfully introduce a gene for a fluorescent protein into the genome of southern house mosquitoes. The gene could be passed on to the next generation through mating. This is a vital component of generating genetic pest management tools. It will allow the desired traits (such as the inability to spread a disease or produce fertile offspring) to be spread throughout a population. The inserted gene produces red fluorescence proteins so that mosquitoes with one or more edited gene fluoresce red. Scientists targeted an eye color gene for the insertion site of the fluorescence gene so mosquitoes that inherited two edited genes from their parents would have white eyes, not black. Both these traits make it easier for scientists to easily identify mosquitoes whose genomes had been modified.
Mosquitoes Sterilized by CRISPR Powered Precision System
18648A. A. Sarkar, Genetic Engineering & Biotechnology News, 2021-09-13 20:06:53.
Each year millions around the world are infected by dengue, chikungunya, and Zika viruses. The principal culprit behind the transmission of these deadly diseases is the mosquito vector, Aedes aegypti. Conventional methods of pest control have so far fallen short. To curb the spread of A. aegypti, researchers at the University of California, San Diego (UCSD), have now developed a CRISPR-based molecular genetic control system called precision-guided sterile insect technique (pgSIT) that alters insect genes to generate flightless female and sterile male mosquitoes. The pgSIT system can be deployed effectively at any stage in the life cycle of the mosquito. The authors used mathematical models to empirically demonstrate that once released, male A. aegypti mosquitoes sterilized using the pgSIT system can compete, suppress, and eliminate fertile mosquito populations in the wild. The pgSIT system is not limited to restricting mosquito populations, it can be adapted to different vectors to curb transmissible diseases in a safe, confinable, and reversible manner, the authors claim. These findings are reported in the Nature Communications article, “Suppressing mosquito populations with precision guided sterile males.”
To exterminate, or not to: Scientists debate tweaking wild genomes
18529French Press Agency, Daily Sabah, 2021-09-12 16:11:31.
veryone remembers Jeff Goldblum's famous speech in 1993 classic Jurassic Park: “Your scientists were so preoccupied with whether they could, they didn't stop to think if they should.” Well, these scientists are debating whether one should. In the movie, reconstructing and tweaking genetic material had made it possible to bring dinosaurs back to life. Today, a technology that manipulates animal genomes, called gene drive, has become a reality. The goal, however, is not to revive long-gone species, but to eliminate invasive ones. Steven Spielberg's film was set on an imaginary island off the coast of Costa Rica, and it is also on an island that the first open-air experiments in programmed extinction could take place, according to experts gathered at the International Union for the Conservation of Nature (IUCN) Congress in Marseille. It could happen within a decade, they told Agence France-Presse (AFP). That's because fragile island ecosystems are in crisis. Dozens of vertebrate species have vanished in the last century, and dozens more are on a glide path to extinction. The culprits are non-native rats, snakes and mosquitoes – all introduced by humans, for the most part by accident – that eat bird eggs, infect birds with disease, or outcompete indigenous amphibians and mammals. For more than 20 years, Island Conservation has been working to eradicate rodents and other invasive alien species, which are a major threat to biodiversity globally, the organization's Royden Saah told AFP. The conservation NGO has been successful on two Galapagos islands – Seymour North and Mosquera – using traps and poison-delivering drones. But species eradication using these tools is costly and has no guarantee of success. Rat poison is effective, but poses risks to other species.
New precision-guided sterile insect technique designed to control disease-spreading mosquitoes
18674E. Henderson, News Medical Life Sciences, 2021-09-11 19:59:16.
Leveraging advancements in CRISPR-based genetic engineering, researchers at the University of California San Diego have created a new system that restrains populations of mosquitoes that infect millions each year with debilitating diseases. The new precision-guided sterile insect technique, or pgSIT, alters genes linked to male fertility--creating sterile offspring--and female flight in Aedes aegypti, the mosquito species responsible for spreading wide-ranging diseases including dengue fever, chikungunya and Zika.Details of the new pgSIT are described September 10, 2021, in the journal Nature Communications. pgSIT differs from "gene drive" systems that could suppress disease vectors by passing desired genetic alterations indefinitely from one generation to the next. Instead, pgSIT uses CRISPR to sterilize male mosquitoes and render female mosquitoes, which spread disease, as flightless. The system is self-limiting and is not predicted to persist or spread in the environment, two important safety features that should enable acceptance for this technology. Akbari says the envisioned pgSIT system could be implemented by deploying eggs of sterile males and flightless females at target locations where mosquito-borne disease spread is occurring.
Scientists debate promise, peril of tweaking wild genomes
18517J. Zamora, Phys Org, 2021-09-11 14:53:57.
In the movie Jurassic Park, reconstructing and tweaking genetic material makes it possible to bring dinosaurs back to life. Today, a technology that manipulates animal genomes, called gene drive, has become a reality. The goal, however, is not to revive long-gone species, but to eliminate invasive ones. Steven Spielberg's film was set on an imaginary island off the coast of Costa Rica, and it is also on an island that the first open-air experiments in programmed extinction could take place, according to experts gathered at the International Union for the Conservation of Nature (IUCN) Congress in Marseille. It could happen within a decade, they told AFP. That's because fragile island ecosystems are in crisis. Dozens of vertebrate species have vanished in the last century, and dozens more are on a glide path to extinction. The culprits are non-native rats, snakes and mosquitoes—all introduced by humans, for the most part by accident—that eat bird eggs, infect birds with disease, or outcompete indigenous amphibians and mammals.
Genetic engineering tech promises to sterilize disease-spreading mosquitoes
18525B. Hays, UPI, 2021-09-10 16:01:17.
Inspired by improvements in CRISPR-based genetic engineering, scientists have developed a more precise insect sterilization system to curtail, or even eliminate, disease-spreading Aedes aegypti mosquito populations. The so-called "precision-guided sterile insect technique," or pgSIT, relies on gene alterations that disrupt fertility in males and flight in females. Gene-altered males are released into a problematic population to compete with healthy males. "pgSIT is a new scalable genetic control system that uses a CRISPR-based approach to engineer deployable mosquitoes that can suppress populations," corresponding author Omar Akbari said in a press release. Map of malaria parasite's gene activity reveals new targets for drugs, vaccines "Males don't transmit diseases so the idea is that as you release more and more sterile males, you can suppress the population without relying on harmful chemicals and insecticides," said Akbari, a professor of biological sciences at the University of California, San Diego.
Genetic Engineering Technology Promises To Sterilize Disease-Spreading Mosquito Populations
18519D. Gyllhem, VIGOURTIMES, 2021-09-10 15:00:02.
Inspired by improvements in CRISPR-based genetic engineering, scientists have developed a more precise insect sterilization system to curtail, or even eliminate, disease-spreading Aedes aegypti mosquito populations. The so-called “precision-guided sterile insect technique,” or pgSIT, relies on gene alterations that disrupt fertility in males and flight in females. Gene-altered males are released into a problematic population to compete with healthy males. Scientists described the novel method in a new paper, published Friday in the journal Nature Communications. “pgSIT is a new scalable genetic control system that uses a CRISPR-based approach to engineer deployable mosquitoes that can suppress populations,” corresponding author Omar Akbari said in a press release. “Males don’t transmit diseases so the idea is that as you release more and more sterile males, you can suppress the population without relying on harmful chemicals and insecticides,” said Akbari, a professor of biological sciences at the University of California, San Diego.
New Technology Designed to Genetically Control Disease-spreading Mosquitoes
18515M. Aguilera, UC San Diego News Center, 2021-09-10 14:49:00.
Leveraging advancements in CRISPR-based genetic engineering, researchers at the University of California San Diego have created a new system that restrains populations of mosquitoes that infect millions each year with debilitating diseases. An illustration by study coauthor Stephanie Gamez depicts flightless females and sterile male mosquitoes, features of the new precision-guided sterile insect technique, or pgSIT, which is designed to control disease-spreading Aedes aegypti mosquitoes. The new precision-guided sterile insect technique, or pgSIT, alters genes linked to male fertility—creating sterile offspring—and female flight in Aedes aegypti, the mosquito species responsible for spreading wide-ranging diseases including dengue fever, chikungunya and Zika. “pgSIT is a new scalable genetic control system that uses a CRISPR-based approach to engineer deployable mosquitoes that can suppress populations,” said UC San Diego Biological Sciences Professor Omar Akbari. “Males don’t transmit diseases so the idea is that as you release more and more sterile males, you can suppress the population without relying on harmful chemicals and insecticides.”
Suppressing mosquito populations with precision guided sterile males
18513M. Li, T. Yang, M. Bui, S. Gamez, T. Wise, N. P. Kandul, J. Liu, L. Alcantara, H. Lee, J. R. Edula, R. Raban, Y. Zhan, Y. Wang, N. DeBeaubien, J. Chen, H. M. Sánchez C, J. B. Bennett, I. Antoshechkin, C. Montell, J. M. Marshall and O. S. Akbari, Nature Communications, 12:5374. 2021-09-10 14:42:45.
The mosquito Aedes aegypti is the principal vector for arboviruses including dengue/yellow fever, chikungunya, and Zika virus, infecting hundreds of millions of people annually. Unfortunately, traditional control methodologies are insufficient, so innovative control methods are needed. To complement existing measures, here we develop a molecular genetic control system termed precision-guided sterile insect technique (pgSIT) in Aedes aegypti. PgSIT uses a simple CRISPR-based approach to generate flightless females and sterile males that are deployable at any life stage. Supported by mathematical models, we empirically demonstrate that released pgSIT males can compete, suppress, and even eliminate mosquito populations. This platform technology could be used in the field, and adapted to many vectors, for controlling wild populations to curtail disease in a safe, confinable, and reversible manner.
Two newly introduced Wolbachia endosymbionts induce cell host differences in competitiveness and metabolic responses
18510T. P. Li, S. S. Zha, C. Y. Zhou, X. Xia, A. A. Hoffmann and X. Y. Hong, Appl Environ Microbiol, Aem0147921. 2021-09-09 14:34:33.
Wolbachia endosymbionts can induce multiple reproductive manipulations in their hosts, with cytoplasmic incompatibility (CI) being one of the most common manipulations. The important agricultural pests, white-backed planthopper (Sogatella furcifera) and brown planthopper (Nilaparvata lugens), are usually infected with CI-inducing Wolbachia wFur and non-CI-inducing Wolbachia wLug, respectively. The biological effects of these infections when present in a host cell are unknown. Here, we introduced the two Wolbachia strains into an Aedes albopictus cell line to stably establish a wFur-infected cell line (WFI) and a wLug-infected cell line (WLI). In a mixed culture, WFI cells were completely replaced by WLI cells, pointing to a stronger competitiveness of the WLI cell line. We found that infection by both Wolbachia strains reduced cell growth rates, but WLI had a faster cell growth rate than WFI, and this difference in cell growth rate combined with possible Wolbachia differences in diffusivity may have affected cell competitiveness. By examining gene expression and metabolites in the two lines, we found that some genes and key metabolites responded to differences in cell competitiveness. These results point to potential mechanisms that could contribute to the relative performance of hosts infected by these strains and also highlight the substantial impact of a non-CI Wolbachia on metabolism, which may in turn influence fitness of its native host. IMPORTANCE Wolbachia transinfection in insects can be used to suppress pests and block virus transmission. We stably introduced two Wolbachia strains from rice planthoppers into cell lines of an important arbovirus mosquito vector, Aedes albopictus. The competitiveness of host cells from the lines infected by the two Wolbachia strains was different, as were metabolic responses of the cell lines. These results suggest potential metabolic effects of Wolbachia on native hosts which could be exploited when they are transinfected into novel hosts for pest control.
Genetically Modified Mosquitoes — What’s The Real Story?
18289SPW Staff, Southeast Product Weekly, 2021-09-02 14:58:32.
You’ve heard about the genetically modified mutant mosquitoes being released in the Florida Keys — but what exactly is going on, and how, and why? Basically, researchers in parts of the Florida Keys are releasing male mosquitoes that have been genetically modified to produce only male offspring. In a generation or two, there are no more girl mosquitoes to have baby mosquitoes. That’s the simple explanation. t might help to know this experiment was tried once before — successfully — in Brazil.There’s now a new, science-based online information resource about genetically modified mosquitoes from University of Florida scientists at the UF/IFAS Florida Medical Entomology Laboratory. “Genetically Modified Mosquitoes” is the latest publication on Ask IFAS, UF/IFAS’ Electronic Data Information Source (EDIS) peer-reviewed site, that provides relevant information regarding the pilot projects in select areas of the Florida Keys. The experiments, which are a collaboration between the Florida Keys Mosquito Control District and the biotechnology company Oxitec founded in the United Kingdom out of Oxford University, are permitted by the U.S. Environmental Protection Agency (EPA).
UF/IFAS Researchers Explain Science Behind Genetically Modified Mosquitoes
18276PCT Staff, Pest Control Technology, 2021-09-01 14:14:47.
South Florida residents seeking science-based information about genetically modified mosquitoes can access a new, online resource from University of Florida scientists at the UF/IFAS Florida Medical Entomology Laboratory.“ Genetically Modified Mosquitoes” is the latest publication on Ask IFAS, UF/IFAS’ Electronic Data Information Source (EDIS) peer-reviewed site, that provides relevant information regarding the pilot projects in select areas of the Florida Keys. The experiments, which are a collaboration between the Florida Keys Mosquito Control District and the biotechnology company Oxitec founded in the United Kingdom out of Oxford University, are permitted by the U.S. Environmental Protection Agency (EPA). The UF/IFAS publication describes the mosquito species being targeted, what to expect from the pilot projects, why this approach is being used as well as answers to other frequently asked questions about genetically modified mosquitoes. The publication also lists additional linked resources for readers interested in more detailed information on the topic and science. “The rationale for producing this document is to help inform the public and those who are interested or impacted by the current trials run by Oxitec,” said Eric Caragata, an assistant professor at UF/IFAS FMEL. “As scientists who are not directly involved in the project, we wanted to clearly address some of the important questions and concerns.”
Millions of Lab-Grown Mosquitoes Are Being Released in Guangzhou
18219F. Yiying, Sixth Tone, 2021-08-25 15:26:45.
Guangzhou is releasing millions of lab-engineered mosquitoes every day to neuter and prevent preexisting mosquitoes in the environment from spreading vector-borne diseases, local television station reported Saturday.The Guangzhou Wolbaki Biotech Co., Ltd., in partnership with the city’s disease control and prevention bureau, releases about five million lab-grown male mosquitoes daily, which only mate with aedes albopictus mosquitoes to stop them from reproducing disease-carrying offspring, according to the media report. Only female aedes albopictus, also known as tiger mosquitoes, prey on people, potentially transmitting the viruses that cause dengue and chikungunya, among other illnesses.The biotech company’s “mosquito factory” in Guangzhou — where dengue fever is a public health concern — breeds mosquitoes to produce offspring carrying the Wolbachia bacteria, which is commonly found in insects and not harmful to humans, before releasing them to the environment. When mosquitoes carrying Wolbachia mate with aedes albopictus, it reduces the replication of the viruses they carry, making them less likely to transmit it to humans.
New Way to Reduce Diseases Spreading Through Mosquitos
18207Dr Jayashree, Medindia, 2021-08-25 15:01:01.
Using a gene editing tool known as CRISPR-Cas9 that targets specific genes tied to fertility in male mosquitoes, we can slow the spread of potentially deadly diseases such as Zika, dengue fever and yellow fever. This genome editing tool is creating a buzz in the science world, as it is faster, cheaper and more accurate than previous techniques of editing DNA and has a wide range of potential applications.. Researchers at the Army's Institute for Collaborative Biotechnologies and the University of California Santa Barbara experimented with the Aedes aegypti mosquitoes, found in tropical, subtropical and temperate regions throughout the world
Gene Editing Could Render Mosquitos Infertile
18168U.S. Army DEVCOM Army Research Laboratory Public Affairs, U.S. Army, 2021-08-23 14:51:29.
CRISPR/Cas9-based functional characterization of the pigmentation gene ebony in Plutella xylostella
18155X. Xu, T. Harvey-Samuel, J. Yang, M. You and L. Alphey, Insect Molecular Biology, 2021-08-20 17:59:44.
Abstract Body pigmentation is an important character of insects in adapting to biotic and abiotic environmental challenges. Additionally, based on the relative ease of screening, several genes involved in insect melanisation have been used in classic genetic studies or as visual markers in constructing transgenic insects. Here, a homolog of the Bombyx mori melanisation-inhibiting gene ebony, associated with the conversion of dopamine to N-?-alanyl dopamine, was identified in a global pest, Plutella xylostella. The CRISPR/Cas9 system was applied to generate multiple Pxebony knockout alleles which were crossed to produce a Pxebony knockout strain, showing darker pigmentation in larvae, pupae and adults, compared with wildtype. Interestingly, we observed that Pxebony heterozygotes displayed an intermediate darkened phenotype, indicating partial dominance between the knockout and wildtype alleles. The fitness costs of Pxebony-deficiency were also assessed in the mutant strain, indicating that embryo hatchability and larval survival were significantly reduced, while the eclosion rate was not obviously affected. Our work provides a potential target for exploring CRISPR-based genetics-control systems in this economically important pest lepidopteran.
Insect pest management in the age of synthetic biology
18682R. Mateos Fernández, M. Petek, I. Gerasymenko, M. Juteršek, Š. Baebler, K. Kallam, E. Moreno Giménez, J. Gondolf, A. Nordmann, K. Gruden, D. Orzaez and N. J. Patron, Plant Biotechnology Journal, 2021-08-20 13:09:26.
Arthropod crop pests are responsible for 20% of global annual crop losses, a figure predicted to increase in a changing climate where the ranges of numerous species are projected to expand. At the same time, many insect species are beneficial, acting as pollinators and predators of pest species. For thousands of years, humans have used increasingly sophisticated chemical formulations to control insect pests but, as the scale of agriculture expanded to meet the needs of the global population, concerns about the negative impacts of agricultural practices on biodiversity have grown. While biological solutions, such as biological control agents and pheromones, have previously had relatively minor roles in pest management, biotechnology has opened the door to numerous new approaches for controlling insect pests. In this review, we look at how advances in synthetic biology and biotechnology are providing new options for pest control. We discuss emerging technologies for engineering resistant crops and insect populations and examine advances in biomanufacturing that are enabling the production of new products for pest control.
The Complex Lives of Mosquitoes: The Key for Malaria Control
18216F. Okumu, ISGlobal, 2021-08-19 15:19:27.
Mosquitoes spread diseases to millions of people around the world, yet they remain poorly understood by most. Studying their biology and behaviours can help us combat, and eventually eliminate, dangerous diseases such as malaria and dengue fever.There are nearly 3,500 species of mosquitoes. About 400 belong to a family called Anopheles, and of these, only about 50-70 can actually transmit malaria to humans. In Africa, where the malaria burden is highest, the most important are Anopheles gambiae, Anopheles funestus, Anopheles arabiensis and Anopheles colluzzi. Often, only one or two of these dominate malaria transmission in any country. Effective malaria control can therefore be achieved by simply identifying, understanding and then targeting just the one or two dominant Anopheles species instead of trying to kill all mosquitoes.A female Anopheles lays about 500 eggs in her lifetime, usually in standing fresh waters, although some breed along rivers or in brackish waters. The eggs weigh just 4 micrograms each and float like little pontoons on the water surfaces
New mosquito control tools are critical
18148L. Braack, Open Access Government, 2021-08-17 17:38:18.
Globally, we are making slow headway in the fight against malaria, but there has been progress, nonetheless. Since 2000, 39 countries and territories have managed to rid themselves of malaria; the most recent is China. Existing tools can achieve local elimination, but the battle is becoming harder and mosquitoes and parasites are able to change their defences, which is why we too have to constantly adapt and respond with better tools and strategies. We should also be on high alert; malaria has been distracting our attention from what will be our next global public health threat: mosquito-borne arboviruses such as Dengue, Chikungunya, Zika, Yellow Fever, West Nile Virus, Usutu, and a host of others few people have heard of. These arboviruses are spreading across the globe, each year more abundant. The mosquitoes that transmit them pose a different set of challenges, as most of them bite by day, with very different breeding habits. We must increase public awareness of the rising threat and invest much greater research effort to find ways to combat these viruses and mosquitoes.
Why Genes That Make Mosquitoes Glow Can Help Reduce Vector-Borne Disease
18143E. Ricciuti, Entomology Today, 2021-08-17 17:21:36.
Fireflies they are not, but glow they do. Not in the dark, to be sure, but mosquitoes genetically modified in the laboratory for an emerging approach to reducing the threat of vector-borne disease look like miniature neon signs when subjected to ultraviolet light. To produce genetically modified, or transgenic, mosquitoes, scientists stich together a construct of mosquito DNA that endows them with a trait that kills off females before they can reproduce, eventually suppressing the surrounding population. Two genes are inserted together into the modified DNA. One is a self-limiting device that prevents female mosquitoes from maturing to adults. The other is a marker that makes the mosquitoes that possess it glow under certain wavelengths of ultraviolet light, facilitating identification when they are collected in monitoring efforts. Scientists at North Carolina State University (NCSU) are trying to give that glow more pizzazz, according to a new study published in July in the Journal of Medical Entomology.
Genetically Modified Mosquitoes
18286E. P. Caragata, Y. Lee and E. A. Buckner, UF IFAS Extension Service, 2021-08-17 14:49:18.
Genetically modified (GM) mosquitoes are controversial, partly because of misinformation. This publication provides science-based information about GM mosquitoes to the public and anyone involved in mosquito control. It explains what GM mosquitoes are and why they are being investigated as a tool for mosquito control. Describes a GM mosquito pilot project in Florida, and includes FAQs and answers explaining how GM mosquitoes are created and their potential impacts on people and the environment.
A Monte Carlo study to investigate the feasibility to use the Moroccan panoramic irradiator in sterile insect technique programs
18159A. Aknouch, Y. El-ouardi, L. Hamroud, R. Sebihi, M. Mouhib, M. Yjjou, A. Didi and A. Choukri, Radiation and Environmental Biophysics, 2021-08-14 18:10:19.
Mediterranean fly pest (Ceratitis) is one of the most destructive pests of fruit species in Morocco. The sterile insect technique (SIT) is an environmentally friendly strategy that uses ionizing radiation to sterilize adult insects. Morocco has a panoramic gamma irradiator used to irradiate agri-food products. This irradiator is not dedicated to SIT programs due to its geometry that does not allow to obtain a dose uniformity ratio (DUR) recommended for such applications. This article presents a Monte Carlo study to investigate the feasibility of using the panoramic gamma irradiator at the National Institute for Agronomic Research (NIAR) of Tangier, Morocco, to setting up SIT methods and contributing to Ceratitis control programs. The Monte Carlo method was used to simulate the concrete bunker in which the panoramic gamma irradiator is installed. To obtain a recommended DUR required for SIT programs, two cells similar of the Gammacell-220 irradiator, which is mainly used in the SIT programs around the world, were simulated inside the concrete bunker. The simulation and calculations were performed using the MCNPX-2.7e Monte Carlo simulation code. It is demonstrated that at both investigated positions, the spatial distribution of dose rates in the two modeled irradiation cells, which were similar to a gammacell-220 irradiator cell, are uniform enough that the cells can be used for SIT programs. It is concluded that the panoramic irradiator at NIAR can be used to contribute to the control of Mediterranean fly pest and other insect pests in Morocco.
Oxitec mosquito release expands
18082T. Java, Keynews.com, 2021-08-11 17:17:55.
Beginning this week, less than 200,000 genetically modified Aedes aegypti male mosquitoes will emerge from Oxitec’s designer bo…
Oxitec eyes California for its next GM mosquito pilot projec
18075J. Conrow, 2021-08-11 17:09:34.
Buoyed by its success in the Florida Keys, Oxitec Ltd. is now looking to California to test its program for controlling mosquito pests through genetic engineering, rather than insecticides. The field research is intended to show that genetically modified (GM) mosquitoes are a viable alternative to spraying insecticides in a bid to control a disease-carrying species of mosquito. Due to climate change, the invasive Aedes aegypti mosquitoes are spreading into new regions throughout the Western United States, including more than 300 cities and towns across California. Aedes aegypti transmit dengue, Zika, heartworm and other diseases, many of which have no treatments or vaccines.
Oxitec Advances Process to Bring Friendly™ Mosquito Technology to California to Help Government Agencies Protect Public Health
18046Oxitec, Oxitec, 2021-08-09 15:11:08.
Following successful launch of its Friendly™ Aedes aegypti pilot program in the Florida Keys, Oxitec, the leading developer of biological solutions to control pests that transmit disease, destroy crops and harm livestock, has requested approval from the U.S. Environmental Protection Agency (EPA) to pilot its technology in California in partnership with local government agencies that have demonstrated interest in evaluating the technology.
GeneConvene Global Collaborative Webinar Series | Invasive Species Management: Informing Gene Drive Considerations
19307David O'Brochta and Hector Quemada, GeneConvene Global Collaborative, 2021-08-07 13:38:24.
The management, control and elimination of invasive species involves solving problems that have analogs to those anticipating the use of gene drive technologies to control and eliminate malaria in Africa. Avoiding unintended consequences from interventions designed to reduce or remove a species from an ecosystem has parallels in some applications of gene drive technologies. Monitoring and surveilling for the movement of invasive species is critical for making management decisions and methods and approaches that have been devised to deal with challenges such as large geographic areas, low species densities, limited resources to name just a few could inform thinking about monitoring and surveillance of gene drive-containing organisms. This series of webinars by invasive species specialists will feature research into how these challenges are being successfully addressed.
Red queen’s race: rapid evolutionary dynamics of an expanding family of meiotic drive factors and their hpRNA suppressors
17957J. Vedanayagam, C.-J. Lin and E. C. Lai, bioRxiv, 2021.08.05.454923. 2021-08-06 16:51:10.
Meiotic drivers are a class of selfish genetic elements that are widespread across eukaryotes. Their activities are often detrimental to organismal fitness and thus trigger drive suppression to ensure fair segregation during meiosis. Accordingly, their existence is frequently hidden in genomes, and their molecular functions are little known. Here, we trace evolutionary steps that generated the Dox meiotic drive system in Drosophila simulans (Dsim), which distorts male:female balance (sex-ratio) by depleting male progeny. We show that Dox emerged via stepwise mobilization and acquisition of portions of multiple D. melanogaster genes, including the sperm chromatin packaging gene protamine. Moreover, we reveal novel Dox homologs in Dsim and massive, recent, amplification of Dox superfamily genes specifically on X chromosomes of its closest sister species D. mauritiana (Dmau) and D. sechellia (Dsech). The emergence of Dox superfamily genes is tightly associated with 1.688 family satellite repeats that flank de novo genomic copies. In concert, we find coordinated emergence and diversification of autosomal hairpin RNA/siRNAs loci that target subsets of Dox superfamily genes across simulans clade species. Finally, an independent set of protamine amplifications the Y chromosome of D. melanogaster indicates that protamine genes are frequent and recurrent players in sex chromosome dynamics. Overall, we reveal fierce genetic arms races between meiotic drive factors and siRNA suppressors associated with recent speciation.Competing Interest StatementThe authors have declared no competing interest.
Transgenic expression of Nix converts genetic females into males and allows automated sex sorting in Aedes albopictus
17888C. Lutrat, R. P. Olmo, T. Baldet, J. Bouyer and E. Marois, bioRxiv, 2021.07.28.454191. 2021-07-29 12:43:42.
Aedes albopictus is a major vector of arboviruses. Better understanding of its sex determination is crucial for developing mosquito control tools, especially genetic sexing strains. In Aedes aegypti, Nix is the primary gene responsible for masculinization and Nix-expressing genetic females develop into fertile, albeit flightless, males. In Ae. albopictus, Nix has also been implicated in masculinization but its role remains to be further characterized. In this work, we established Ae. albopictus transgenic lines ectopically expressing Nix. Several were composed exclusively of genetic females, with transgenic individuals being phenotypic and functional males due to the expression of the Nix transgene. Their reproductive fitness was marginally impaired, while their flight performance was similar to controls. Overall, our results show that Nix is sufficient for full masculinization in Ae. albopictus. Moreover, the transgene construct contains a fluorescence marker allowing efficient automated sex sorting. Consequently, such strains constitute valuable sexing strains for genetic control.Competing Interest StatementThe authors have declared no competing interest.
Horizontal Transmission of the Symbiont Microsporidia MB in Anopheles arabiensis
17856G. Nattoh, T. Maina, E. E. Makhulu, L. Mbaisi, E. Mararo, F. G. Otieno, T. Bukhari, T. O. Onchuru, E. Teal, J. Paredes, J. L. Bargul, D. M. Mburu, E. A. Onyango, G. Magoma, S. P. Sinkins and J. K. Herren, Frontiers in Microbiology, 12. 2021-07-28 13:43:29.
The recently discovered Anopheles symbiont, Microsporidia MB, has a strong malaria transmission-blocking phenotype in Anopheles arabiensis, the predominant Anopheles gambiae species complex member in many active transmission areas in eastern Africa. The ability of Microsporidia MB to block Plasmodium transmission together with vertical transmission and avirulence makes it a candidate for the development of a symbiont-based malaria transmission blocking strategy. We investigate the characteristics and efficiencies of Microsporidia MB transmission between An. arabiensis mosquitoes. We show that Microsporidia MB is not transmitted between larvae but is effectively transmitted horizontally between adult mosquitoes. Notably, Microsporidia MB was only found to be transmitted between male and female An. arabiensis, suggesting sexual horizontal transmission. In addition, Microsporidia MB cells were observed infecting the An. arabiensis ejaculatory duct. Female An. arabiensis that acquire Microsporidia MB horizontally are able to transmit the symbiont vertically to their offspring. We also investigate the possibility that Microsporidia MB can infect alternate hosts that live in the same habitats as their An. arabiensis hosts, but find no other non-anopheline hosts. Notably, Microsporidia MB infections were found in another primary malaria African vector, Anopheles funestus s.s. The finding that Microsporidia MB can be transmitted horizontally is relevant for the development of dissemination strategies to control malaria that are based on the targeted release of Microsporidia MB infected Anopheles mosquitoes.
Oxitec and MosquitoMate in the United States: lessons for the future of gene drive mosquito control
17890C. E. Schairer, J. Najera, A. A. James, O. S. Akbari and C. S. Bloss, Pathogens and Global Health, 2021-07-27 12:51:01.
ABSTRACTIn response to growing concerns regarding mosquito-borne diseases, scientists are developing novel systems of vector control. Early examples include Oxitec?s OX513A genetically-engineered mosquito and MosquitoMate?s Wolbachia-infected mosquito, and systems using ?gene-drive? are in development. Systems based on genetic engineering are controversial and institutions around the world are grappling with the question of who should have a say in how such technologies are field-tested and used. Based on media coverage and public records, we created comparative timelines of the efforts of Oxitec and MosquitoMate to navigate federal and local governance and bring their products to market in the United States. We analyze these timelines with particular attention to the role of public input in technology governance. These cases illustrate how governance of technology in the US is diverse, complex, and opaque. Further, the public response to proposed field trials of the Oxitec product highlights inconsistencies between public expectations for governance and actual practice. As gene-drive mosquito control products develop, both federal and local agencies will find their legitimacy tested without a better procedure for transparently integrating public input.
Gene drive strategies of pest control in agricultural systems: challenges and opportunities
17836M. Legros, J. M. Marshall, S. Macfadyen, K. R. Hayes, A. Sheppard and L. G. Barrett, Evolutionary Applications, 2021-07-26 14:04:32.
Abstract Recent advances in gene editing technologies have opened new avenues for genetic pest control strategies, in particular around the use of gene drives to suppress or modify pest populations. Significant uncertainty, however, surrounds the applicability of these strategies to novel target species, their efficacy in natural populations, and their eventual safety and acceptability as control methods. In this article we identify issues associated with the potential use of gene drives in agricultural systems, to control pests and diseases that impose a significant cost to agriculture around the world. We first review the need for innovative approaches, and provide an overview of the most relevant biological and ecological traits of agricultural pests that could impact the outcome of gene drive approaches. We then describe the specific challenges associated with using gene drives in agricultural systems, as well as the opportunities that these environments may offer, focusing in particular on the advantages of high-threshold gene drives. Overall we aim to provide a comprehensive view of the potential opportunities and the remaining uncertainties around the use of gene drives in agricultural systems.
The Aedes aegypti (Diptera: Culicidae) hsp83 Gene Promoter Drives Strong Ubiquitous DsRed and ZsGreen Marker Expression in Transgenic Mosquitoes
18145S. H. Webster and M. J. Scott, Journal of Medical Entomology, 2021-07-24 17:29:43.
Transgenic strains of the mosquito disease vector Aedes aegypti (L.) are being developed for population suppression or modification. Transgenic mosquitoes are identified using fluorescent protein genes. Here we describe DsRed and ZsGreen marker genes driven by the constitutive Ae. aegypti heat shock protein 83 (hsp83) promoter in transgenic mosquitoes. Transgenic larvae and pupae show strong full body expression of the red and green fluorescent proteins. This greatly assists in screening for transgenic individuals while making new or maintaining already established lines. Transient marker gene expression after embryo microinjection was readily visible in developing larvae allowing the separation of individuals that are more likely to produce transgenic offspring. The strongly expressed marker genes developed in this study should facilitate the detection of transgenic Ae. aegypti larvae or pupae in the field.
Sex separation of Aedes spp. mosquitoes for sterile insect technique application: a review
17905B. M. Moran-Aceves, C. F. Marina, A. Dor, P. Liedo and J. Toledo, Entomologia Experimentalis Et Applicata, 10. 2021-07-24 15:04:30.
Separation of the sexes is necessary for the application of the sterile insect technique (SIT) in mosquitoes due to the hematophagous habits and disease vector activity of the females. In this review we analyze the history, current status, and future perspectives for the development of genetic sexing strains (GSS) of Aedes mosquitoes (Diptera: Culicidae). Various genetic control methods for mosquitoes are reviewed, as are their need for sex-separation methods. We focus on areas of opportunity where GSS developed with classical genetic methods can be used. Regulatory restrictions and social acceptance of various control methods are analyzed. We conclude that the development of GSS by classical methods represents the most viable option for separation of the sexes and the application of large-scale SIT programs within an area-wide integrated vector management (AW-IVM) approach.
Wolbachia as translational science: controlling mosquito-borne pathogens
17799E. P. Caragata, H. L. C. Dutra, P. H. F. Sucupira, A. G. A. Ferreira and L. A. Moreira, Trends in Parasitology, 2021-07-22 20:54:55.
In this review we examine how exploiting the Wolbachia?mosquito relationship has become an increasingly popular strategy for controlling arbovirus transmission. Field deployments of Wolbachia-infected mosquitoes have led to significant decreases in dengue virus incidence via high levels of mosquito population suppression and replacement, emphasizing the success of Wolbachia approaches. Here, we examine how improved knowledge of Wolbachia?host interactions has provided key insight into the mechanisms of the essential phenotypes of pathogen blocking and cytoplasmic incompatibility. And we discuss recent studies demonstrating that extrinsic factors, such as ambient temperature, can modulate Wolbachia density and maternal transmission. Finally, we assess the prospects of using Wolbachia to control other vectors and agricultural pest species.
CRISPR/Cas-9 mediated knock-in by homology dependent repair in the West Nile Virus vector Culex quinquefasciatus Say
17811D.-K. Purusothaman, L. Shackleford, M. A. E. Anderson, T. Harvey-Samuel and L. Alphey, Scientific Reports, 11:14964. 2021-07-22 14:14:08.
Culex quinquefasciatus Say is a mosquito distributed in both tropical and subtropical regions of the world. It is a night-active, opportunistic blood-feeder and vectors many animal and human diseases, including West Nile Virus and avian malaria. Current vector control methods (e.g. physical/chemical) are increasingly ineffective; use of insecticides also imposes hazards to both human and ecosystem health. Advances in genome editing have allowed the development of genetic insect control methods, which are species-specific and, theoretically, highly effective. CRISPR/Cas9 is a bacteria-derived programmable gene editing tool that is functional in a range of species. We describe the first successful germline gene knock-in by homology dependent repair in C. quinquefasciatus. Using CRISPR/Cas9, we integrated an sgRNA expression cassette and marker gene encoding a fluorescent protein fluorophore (Hr5/IE1-DsRed, Cq7SK-sgRNA) into the kynurenine 3-monooxygenase (kmo) gene. We achieved a minimum transformation rate of 2.8%, similar to rates in other mosquito species. Precise knock-in at the intended locus was confirmed. Insertion homozygotes displayed a white eye phenotype in early-mid larvae and a recessive lethal phenotype by pupation. This work provides an efficient method for engineering C. quinquefasciatus, providing a new tool for developing genetic control tools for this vector.
Using Moderate Transgene Expression to Improve the Genetic Sexing System of the Australian Sheep Blow Fly Lucilia cuprina
17753Y. Yan, M. E. Williamson and M. J. Scott, Insects, 11. 2021-07-19 14:36:16.
The sterile insect technique (SIT) is a promising strategy to control the Australian sheep blow fly Lucilia cuprina, a major pest of sheep. We have previously developed a transgenic embryonic sexing system (TESS) for this pest to facilitate the potential SIT application. TESS carry two transgenes, a tetracycline transactivator (tTA) driver and a tTA-activated pro-apoptotic effector. TESS females die at the embryonic stage unless tetracycline is supplied in the diet. However, undesired female sterility was observed in some TESS strains without tetracycline due to expression of tTA in ovaries. Here we investigate if TESS that combine transgenes with relatively low/moderate expression/activity improves the fertility of TESS females. tTA driver lines were evaluated for tTA expression by quantitative real time PCR and/or by crossing with a tTA-activated RFPex effector line. Fertility and lethality tests showed that a TESS strain containing a driver line with moderate tTA expression and an effector line showing moderate pro-apoptotic activity could recover the fertility of parental females and eliminated all female offspring at the embryonic stage. Consequently, such a strain could be further evaluated for an SIT program for L. cuprina, and such a “moderate strategy” could be considered for the TESS development in other pest species.
Combating mosquito-borne diseases using genetic control technologies
17735G.-H. Wang, S. Gamez, R. R. Raban, J. M. Marshall, L. Alphey, M. Li, J. L. Rasgon and O. S. Akbari, Nature Communications, 12:4388. 2021-07-19 13:06:45.
Mosquito-borne diseases, such as dengue and malaria, pose significant global health burdens. Unfortunately, current control methods based on insecticides and environmental maintenance have fallen short of eliminating the disease burden. Scalable, deployable, genetic-based solutions are sought to reduce the transmission risk of these diseases. Pathogen-blocking Wolbachia bacteria, or genome engineering-based mosquito control strategies including gene drives have been developed to address these problems, both requiring the release of modified mosquitoes into the environment. Here, we review the latest developments, notable similarities, and critical distinctions between these promising technologies and discuss their future applications for mosquito-borne disease control.
The Possible Role of Microorganisms in Mosquito Mass Rearing
17741L. Chersoni, A. Checcucci, M. Malfacini, A. Puggioli, F. Balestrino, M. Carrieri, I. Piunti, M. L. Dindo, P. Mattarelli and R. Bellini, Insects, 12. 2021-07-15 13:10:37.
In Europe, one of the most significant mosquitoes of public health importance is Aedes albopictus (Skuse), an allochthonous species of Asian origin. One of the most promising control methods against Aedes albopictus is the sterile insect technique (SIT), which consists of mass rearing the target species, separation of males from females, and male exposure to sterilizing ionizing radiation. Once released in the environment, the sterile males are expected to search for wild females to mate with. If mating occurs, no offspring is produced. The quality of sterile males is a crucial aspect in SIT programs in order to optimize effectiveness and limit production costs. The integration of probiotic microorganisms in larval and adult mosquito diets could enhance the quality parameters of the released sterile males. In this review, we attempt to give the most representative picture of the present knowledge on the relationships between gut microbiota of mosquitoes and the natural or artificial larval diet. Furthermore, the possible use of probiotic microorganisms for mosquito larvae rearing is explored. Based on the limited amount of data found in the literature, we hypothesize that a better understanding of the interaction between mosquitoes and their microbiota may bring significant improvements in mosquito mass rearing for SIT purposes.
Sterile Insect Technique (SIT) and Its Applications
17733K. Bourtzis and M. J. B. Vreysen, Insects, 12. 2021-07-13 15:57:10.
Although most insect species have a beneficial role in the ecosystems, some of them represent major plant pests and disease vectors for livestock and humans. During the last six–seven decades, the sterile insect technique (SIT) has been used as part of area-wide integrated pest management strategies to suppress, contain, locally eradicate or prevent the (re)invasion of insect pest populations and disease vectors worldwide. This Special Issue on “Sterile insect technique (SIT) and its applications”, which consists of 27 manuscripts (7 reviews and 20 original research articles), provides an update on the research and development efforts in this area. The manuscripts report on all the different components of the SIT package including mass-rearing, development of genetic sexing strains, irradiation, quality control as well as field trials.
Unique effort underway to control deadly mosquitos in Florida Keys
17823K. Corso and L. Aguirre, Local10.com, 2021-07-12 14:48:28.
According to the World Health Organization, more than 50% of the world’s population is under the threat of mosquito borne diseases. In South Florida, the Keys are a hot spot for infection and now the first place in the United States for a novel approach to eradicating these deadly insects. A mosquito control effort in the works for over a decade is now off the ground. The Oxitec Project uses genetically modified Aedes Aegypti male mosquitos to mate with females of the Aedes Aegypti species which carry some of the deadliest diseases “Ades Aegypti themselves are responsible for transmitting Yellow Fever, Dengue Fever, Chikungunya, Zika virus, said Andrea Leal, entomologist and executive director of the Florida Keys Mosquito Control District. Only the female mosquitos bite so the Oxitec Project targets the female population of the species. “So with this project, we’re releasing males only and they’ve been modified with a female lethal gene which means as they go out and they mate with our wild females, all those female offspring will die,” Leal said.
Improvement of the Mass-Rearing Protocols for the South American Fruit Fly for Application of the Sterile Insect Technique
17764T. Mastrangelo, A. Kovaleski, B. Maset, M. D. Costa, C. Barros, L. A. Lopes and C. Caceres, Insects, 12. 2021-07-09 14:59:26.
The existing rearing protocols for Anastrepha fraterculus must be reviewed to make economically viable the production of sterile flies for their area-wide application. Additionally, evidence of sexual incompatibility between a long-term mass-reared Brazilian strain and wild populations has been found. To address these issues, this study aimed to refine rearing protocols and to assess the suitability of an A. fraterculus strain for the mass production of sterile flies. A series of bioassays were carried out to evaluate incubation times for eggs in a bubbling bath and to assess the temporal variation of egg production from ovipositing cages at different adult densities. A novel larval diet containing carrageenan was also evaluated. Egg incubation times higher than 48 h in water at 25 °C showed reduced larval and pupal yields. Based on egg production and hatchability, the density of 0.3 flies/cm2 can be recommended for adult cages. The diet with carrageenan was suitable for mass production at egg-seeding densities between 1.0 and 1.5 mL of eggs/kg of diet, providing higher insect yields than a corn-based diet from Embrapa. Even after two years of being reared under the new rearing protocols, no sexual isolation was found between the bisexual strain and wild flies.
Fighting disease: How are genetically engineered mosquitoes regulated?
17652A. Julie, Global News, 2021-07-08 19:26:36.
Mosquitoes have long been associated with the spread of diseases like malaria, dengue fever and the Zika virus. But scientists around the world have been exploring the possibility that mosquitoes could also be key to slowing the spread of disease. By genetically altering the DNA of mosquitoes, scientists hope to prevent them from passing on pathogens to humans and, therefore, control the spread of vector-borne diseases. To some, it is an exciting opportunity that could open up new possibilities in the fight against endemic diseases. But the practice has also raised questions from some in the scientific and environmental communities about the impact on local ecosystems, and the ripple effects such modifications could have on the mosquito populations themselves.
Comparative response to post-production process of two Anastrepha ludens strains: Application in the sterile insect technique
17725J. Arredondo, J. F. Aguirre-Medina, J. S. Meza, J. Cancino and F. Diaz-Fleischer, Journal of Applied Entomology, 11. 2021-07-07 14:54:23.
The new desiccation-resistant (DR) strain of Anastrepha ludens Loew differs in its life-history traits from the non-selected strain (NS). Given the innate resistance of DR flies to stressors, it is necessary to determine the packing and shipment conditions for their use in the sterile insect technique (SIT). First, we used pupae to evaluate the interaction of hypoxia period (12, 24 and 36 hr) and temperature (15.3 (+/- 0.9), 19.5 (+/- 1.0), 25.5 (+/- 0.6) and 30.1 (+/- 0.5) C-o). Second, adults were exposed to densities of 1.0, 1.3 and 1.5 flies/cm(2) and chilling periods of 0, 3 and 5 hr. We observed a negative relationship of emergence and flight ability with hypoxia period and temperature in both strains especially when flies were exposed to 36 hr of hypoxia and 30celcius. Interestingly, knock-down time decreased as male density increased, but when chilling time increased, recovery time also increased. Both chilling time and male density had negative effects on male weight. Chilling time reduced male survival when exposed to desiccation, while both chilling time and male density decreased male survival under starvation conditions. Negative effects on number of matings were observed only on the first day after chilling but not on the following days. We found that DR flies survive approximately twice as long as flies from the NS strain when exposed to starvation or desiccation stressors. We discuss our results on the basis of the potential use of DR flies in SIT programmes.
Effect of the timing of pupal irradiation on the quality and sterility of oriental fruit flies (Diptera: Tephritidae) for use in Sterile Insect Technique
17781T. J. Fezza, P. A. Follett and T. E. Shelly, Applied Entomology and Zoology, 8. 2021-07-05 17:37:25.
The Sterile Insect Technique (SIT) is a target-specific, biologically based method used to control pestiferous tephritids entailing the release of mass-reared, sterilized males of the target species to achieve sterile male x wild female matings. As documented for several tephritid species, sterilizing irradiation may have adverse effects on various biological parameters, including life span, flight ability, and mating competitiveness. To minimize these impacts and ensure sterility, released flies must be irradiated at a precise dose at a specific and uniform age. The objective of the present study was to determine the impact of pupal age at the time of irradiation on flight ability, male survival, fertility, and mating competitiveness for the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) irradiated at 100 Gy. We concluded that flies irradiated as pupae 4 days before emergence were significantly compromised with respect to flight ability and male survival when compared to flies irradiated 1 or 2 days before emergence. Additionally, we determined that crosses between males irradiated 1 day before emergence with non-irradiated females yielded significantly more pupae than the same cross with males irradiated at 2, 3, and 4 days before emergence. Although rare, the occurrence of pupae and emerged adults suggested low levels of fertility for flies irradiated as pupae 1 day before emergence, but complete sterility at 2, 3, and 4 days before emergence. These findings suggest that SIT programs can potentially irradiate pupae at 2 or 3 days before emergence without compromising the quality of the released flies, which would permit the distribution of flies over greater distances.
Gene drive that results in addiction to a temperature sensitive version of an essential gene triggers population collapse in Drosophila
17609G. Oberhofer, B. Hay and T. Ivy, bioRxiv, 2021.07.03.451005. 2021-07-04 14:38:01.
One strategy for population suppression seeks to use gene drive to spread genes that confer conditional lethality or sterility, providing a way of combining population modification with suppression. Stimuli of potential interest could be introduced by humans, such as an otherwise benign virus or chemical, or occur naturally on a seasonal basis, such as a change in temperature. Cleave and Rescue (ClvR) selfish genetic elements use Cas9 and gRNAs to disrupt endogenous versions of an essential gene, while also including a Rescue version of the essential gene resistant to disruption. ClvR spreads by creating loss-of-function alleles of the essential gene that select against those lacking it, resulting in populations in which the Rescue provides the only source of essential gene function. In consequence, if function of the Rescue, a kind of Trojan horse now omnipresent in a population, is condition-dependent, so too will be the survival of that population. To test this idea we created a ClvR in Drosophila in which Rescue activity of an essential gene, dribble, requires splicing of a temperature-sensitive intein (TS-ClvRdbe). This element spreads to transgene fixation at 23° C, but when populations now dependent on TS-ClvRdbe are shifted to 29° C death and sterility result in a rapid population crash. These results show that conditional population elimination can be achieved. A similar logic, in which Rescue activity is conditional, could also be used in HEG-based drive, and to bring about suppression and/or killing of specific individuals in response to other stimuli.Competing Interest StatementThe authors have filed patent applications on ClvR and related 336 technologies (U.S. Application No. 15/970,728 and No. 16/673,823 ; provisional patent No. 337 CIT-8511-P )
The (Losing) Battle Against Mosquitoes In Texas
17599J. Clayton, Texas Public Radio, 2021-06-26 14:13:20.
Jerry Clayton: Mosquitoes are a fact of life in Texas, and the battle against the pesky biting insects is never ending. But there are some new weapons on the horizon. Zach Adleman is an associate professor of entomology at Texas A&M University. He joins us today. Thanks for being here, Zach.
A transgenic female killing system for the genetic control of Drosophila suzukii
17506M. F. Schetelig, J. Schwirz and Y. Yan, Scientific Reports, 11:12938. 2021-06-24 14:13:24.
The spotted wing Drosophila (Drosophila suzukii) is an invasive pest of soft-skinned fruit crops. It is rapidly transmitted in Europe and North America, causing widespread agricultural losses. Genetic control strategies such as the sterile insect technique (SIT) have been proposed as environment-friendly and species-restricted approaches for this pest. However, females are inefficient agents in SIT programs. Here we report a conditional female-killing (FK) strategy based on the tetracycline-off system. We assembled sixteen genetic constructs for testing in vitro and in vivo. Twenty-four independent transgenic strains of D. suzukii were generated and tested for female-specific lethality. The strongest FK effect in the absence of tetracycline was achieved by the construct containing D. suzukii nullo promoter for early gene expression, D. suzukii pro-apoptotic gene hidAla4 for lethality, and the transformer gene intron from the Mediterranean fruit fly Ceratitis capitata for female-specific splicing. One strain carrying this construct eliminated 100% of the female offspring during embryogenesis and produced only males. However, homozygous females from these FK strains were not viable on a tetracycline-supplemented diet, possibly due to the basal expression of hidAla4. Potential improvements to the gene constructs and the use of such FK strains in an SIT program are discussed.
Manipulated Mosquitoes Cut Dengue by 77%
17513T. Hayes, Healthcare Packaging, 2021-06-22 14:34:21.
Dengue, a mosquito-borne viral disease, wasn’t that common 50 years ago. In fact, only nine countries had severe outbreaks. But since then, it’s been on a steady incline to the point that there are now 400 million infections a year that contribute to 22,000 deaths. Thankfully, we have the World Mosquito Programme, a group that’s fighting the tropical mosquito disease head-on with genetically modified mosquitoes. The insects are infected with Wolbachia, a bacteria that inhibits viruses’ ability to live inside the insects, and also controls reproduction so that offspring are also infected with the bacteria. The result is a new population of insects that can’t transmit viruses like dengue, yellow fever and Zika. The study in Indonesia included 8,000 people, and concluded with protective efficacy of 77.1%.
Why Are Gates and Pentagon Releasing GMO Mosquitoes in Florida Keys?
17516F. W. Engdahl, LewRockwell.com, 2021-06-21 14:40:32.
On April 30 the Florida Keys Mosquito Control District and the Oxitec biotechnology company announced they will begin release of what will ultimately be some 750 million genetically manipulated or gene-edited Aedes Aegypti mosquitos using CRSPR gene editing technology. The Aedes Aegypti makes up only about 4% of the mosquito population in the Keys. The release is bitterly opposed by residents and environmental groups who demanded a referendum in last year’s election ballot, but which the Mosquito Control Board refused, curiously. Oxitec and the Board claim the release is to kill off the presence of the Aedes Aegypti mosquito which is believed to carry dengue fever, Zika and other diseases. The project, which sounds positive in the press statements, is alarming in many respects. First, the refusal to allow a citizen vote on the controversial GMO release. Second, there exists no cost-benefit analysis of the risks versus benefits of releasing millions of mosquitoes whose genetic traits are mutating in often unpredictable ways. Is it worth the risk that an ever more robust variety of mosquito will mutate from the project? No one can say. Traditional mosquito control techniques have worked well until now.
Dengue fever: Upstaged but not outmatched by COVID-19
17490C. E. Baclig, INQUIRER.NET, 2021-06-17 15:17:30.
Science has made gains in the war on dengue and other diseases that mosquitoes carry, like malaria.One of these is the World Mosquito Program (WMP), a non-profit initiative that aims to protect the global community from mosquito-borne viral diseases, by deploying a natural bacteria, called Wolbachia. On its website, WMP said its scientists had discovered that Aedis aegypti mosquitoes carry Wolbachia, a bacteria which competes with viruses like dengue, zika, chikungunya, and the virus that causes yellow fever. Wolbachia, WMP said, was found to make it difficult for viruses to reproduce inside mosquitoes. Mosquitoes carrying Wolbachia, WPS said, “are much less likely to spread viruses from person to person.” Wolbachia is found in 60 percent of insects but is not normally carried by Aedis aegypti mosquitoes. So scientists injected the bacteria into mosquito eggs. Once these hatches and send off grown mosquitoes, they are released to breed with local mosquito populations.
Genetically Modified Mosquitoes; ‘Truth Like Oil’ Novel
17487Here and Now, WBUR, 2021-06-16 15:10:42.
Florida Keys officials are working on a unique experiment: hatching thousands of genetically modified mosquitos and releasing them. Andrea Leal of the Florida Keys Mosquito Control District explains.
Selfish DNA: how new gene technology could stop the advance of mice
17450M. McMillan, Tentenfield Star, 2021-06-15 17:20:08.
It used to be that seeing a mouse in the house was a rare occurrence. Now, it's rarely a day that goes by where we aren't seeing or hearing the little vermin. Current methods of baiting and trapping are struggling to control the plague of mice spreading across regional Australia. But a $1.8 million investment from the NSW government might soon give us a new weapon in the war. The government is investing in research into the use of gene drives, or "selfish DNA" - a genetic tool that can help us to control pests. How? Well, to understand gene drives we first need to understand the normal way in which genes are inherited. Mice, like humans, have two copies of each gene, one inherited from their mother and one from their father. We call these copies alleles, and they can be exactly the same or slightly different from each other. Normally, there is a 50/50 chance as to which allele will be passed on to any offspring. If one allele carries some sort of mutation, there is a 50 per cent chance that it will be passed on.
Dengue Infections Can Be Sharply Reduced With Wolbachia Bacteria
17453J. Stone, Medscape, 2021-06-14 17:25:12.
A modestly titled new study released in the New England Journal of Medicine belies the extraordinary 77% protective efficacy reported for preventing dengue infections with Wolbachia-infected Aedes aegypti mosquitoes. A cluster-randomized clinical trial, the AWED ("Applying Wolbachia to Eliminate Dengue") study was conducted in Yogyakarta, Indonesia and led by professors Adi Utarini, MD, PhD, of Gadjah Mada University and Cameron Simmons, PhD, the World Mosquito Program's Oceana director, in partnership with the Tahija Foundation and Monash University.
Making mosquitoes to fight mosquitoes to prevent dengue
17484A. George, Times of India, 2021-06-14 15:04:01.
In 2017, Delhi Chief Minister Arvind Kejriwal tweeted that the national capitl needed to be made mosquito-free. The same year, his Kerala counterpart, Pinaray Vijayan, called a three-day state-wide cleanliness drive as hospitals filled with genue patients.
Temperature-Inducible Precision Guided Sterile Insect Technique
17447N. P. Kandul, J. Liu and O. S. Akbari, bioRxiv, 2021.06.14.448312. 2021-06-14 13:13:08.
Releases of sterile males are the gold standard for many insect population control programs, and precise sex sorting to remove females prior to male releases is essential to the success of these operations. To advance traditional methods for scaling the generation of sterile males, we previously described a CRISPR-mediated precision-guided sterile insect technique (pgSIT), in which Cas9 and gRNA strains are genetically crossed to generate sterile males for release. While effective at generating F1 sterile males, pgSIT requires a genetic cross between the two parental strains which requires maintenance and sexing of two strains in a factory. Therefore, to further advance pgSIT by removing this crossing step, here we describe a next-generation Temperature-Inducible pgSIT (TI-pgSIT) technology and demonstrate its proof-of-concept in Drosophila melanogaster. Importantly, we were able to develop a true-breeding strain for TI-pgSIT that eliminates the requirement for sex sorting, a feature that may help further automate production at scale.
The First Genetically Modified Mosquitoes Have Just Been Released in The US
17303Admin, Science World, 2021-06-11 11:14:27.
The biotech firm Oxitec has released its genetically modified mosquitoes in the Florida Keys, with the goal of suppressing wild, disease-carrying mosquito populations in the region. This is the first time genetically modified mosquitoes have been released in the US. Oxitec previously released its modified Aedes aegypti mosquitoes in Brazil, the Cayman Islands, Panama, and Malaysia, and the company reported that local A. aegypti populations fell by at least 90 percent in those locations, Live Science previously reported. A. aegypti can carry diseases such as Zika, dengue, chikungunya, and yellow fever, and releasing modified mosquitoes offers a way to control the population without using pesticides. Oxitec's modified mosquitoes, all male, have been engineered to carry a lethal gene; when the modified pests mate with wild female mosquitoes, the lethal gene gets passed on to their offspring.
Using Wolbachia to Eliminate Dengue: Will the Virus Fight Back?
18270M. Edenborough Kathryn, A. Flores Heather, P. Simmons Cameron, E. Fraser Johanna and C. Pierson Ted, Journal of Virology, 95:e02203-20. 2021-06-10 14:06:11.
Recent fieldtrials havedemonstratedthatdengue incidence can besubstantially reduced by introgressing strains of the endosymbiotic bacterium Wolbachia into Aedes aegypti mosquito populations. This strategy relies on Wolbachia reducing the susceptibility of Ae. aegypti to disseminated infection by positive-sense RNA viruses like dengue. However, RNA viruses are well known to adapt to antiviral pressures. Here, we review the viral infection stages where selection for Wolbachia-resistant virus variants could occur. We also consider the genetic constraints imposed on viruses that alternate between vertebrate and invertebrate hosts, and the likely selection pressures to which dengue virus might adapt in order to be effectively transmitted by Ae. aegypti that carry Wolbachia. While there are hurdles to dengue viruses developing resistance to Wolbachia, we suggest that long-term surveillance for resistant viruses should be an integral component of Wolbachia-introgression biocontrol programs.
Dengue Fever Cut Down by 77% With Groundbreaking Bacteria-Armed Mosquitoes
17322M. Davis, The Science Times, 2021-06-10 12:02:22.
Scientists found that dengue fever cases have decreased by 77% in a groundbreaking trial that took place in Yogyakarta City, Indonesia. They used Wolbachia-infected mosquitoes that reduced their ability to spread the dengue fever. The team at the World Mosquito Program said that this could be a solution to dengue fever that is prevalent around the world. Dr. Katie Anders, one of the researchers, described the trial of using Wolbachia-infected mosquitoes in Indonesia as a "naturally miraculous" solution. Wolbachia is a virus-fighting bacteria that has been approved since 2017 by the Environmental Protection Agency (EPA) for use in the United States. Other interventions, like genetically modified mosquitoes, are also used to combat dengue fever and other diseases caused by mosquitoes. According to BBC News, Wolbachia does not harm the mosquito, but it will only be stored in the same parts of the mosquito's body where the dengue virus is kept. It competes for the resources, preventing the dengue virus to replicate, and therefore the mosquito is less likely to cause the infection when it bites. Moreover, Wolbachia bacteria can also manipulate and alter the fertility of their hosts. They make sure that they are passed on to the next generation of mosquitoes, which means they are established and should stick around for a long time to continue their protective abilities against dengue fever.
Mosquito ‘bacteria hack’ nearly eliminates dengue fever and could save millions of lives
17316A. Wilkins, METRO, 2021-06-10 11:50:12.
Mosquitoes infected with a ‘miraculous’ bacteria have been shown to reduce dengue fever cases by 77%, in a groundbreaking new study. Scientists released mosquitoes infected with ‘Wolbachia’ bacteria into the Indonesian city of Yogyakarta – but only in certain zones. In the zones where the modified mosquitoes had been released, cases of dengue fell by 77% and hospitalisations dropped by 86%. The results of the study, carried out by the World Mosquito Programme (WMP), were ‘better than we could have hoped for’, according to researcher Dr. Katie Anders. Cases of dengue fever, a virus that can cause muscle and bone pain, and death, have risen rapidly in the past decades – there are an estimated 400 million cases a year. The Wolbachia bacteria used in the trial were chosen because it hides in the same parts of a mosquito’s body that dengue virus hides in. A bacteria that is benign to humans, the Wolbachia then competes for resources with the dengue virus, which makes it less likely for the mosquito to cause a dengue infection when it bites a human.
‘Miraculous’ mosquito hack cuts dengue by 77%
17311J. Gallagher, BBC, 2021-06-10 11:38:57.
Dengue fever cases have been cut by 77% in a "groundbreaking" trial that manipulates the mosquitoes that spread it, say scientists. They used mosquitoes infected with "miraculous" bacteria that reduce the insect's ability to spread dengue. The trial took place in Yogyakarta city, Indonesia, and is being expanded in the hope of eradicating the virus. The World Mosquito Programme team says it could be a solution to a virus that has gone around the world. Few people had heard of dengue 50 years ago, but it has been a relentless slow-burning pandemic and cases have increased dramatically. In 1970, only nine countries had faced severe dengue outbreaks, now there are up to 400 million infections a year. Dengue is commonly known as "break-bone fever" because it causes severe pain in muscles and bones and explosive outbreaks can overwhelm hospitals.
Modified mosquitoes reduce dengue cases by 77% in Indonesia experiment
17309M. Fox, CNN, 2021-06-10 11:32:59.
An experiment to infect mosquitoes with bacteria that stop them from transmitting viruses appears to have helped reduced the spread of deadly dengue virus in Indonesia, researchers reported Wednesday. The modified mosquitoes thrived for three years, and cases of dengue were reduced by 77% in areas where they were introduced, the researchers reported in the New England Journal of Medicine. The mosquitoes are infected with bacteria called Wolbachia, which not only interfere with the ability of viruses to live in the bodies of the insects, but which also control reproduction so that the mosquitoes only have Wolbachia-infected offspring. The result is a growing population of insects that don't pass on viruses such as dengue, yellow fever and Zika. The study involved more than 8,000 people, about half of whom lived in areas where the modified Aedes aegypti mosquitoes had been living and breeding.
Efficacy of Wolbachia-Infected Mosquito Deployments for the Control of Dengue
17300A. Utarini, C. Indriani, R. A. Ahmad, W. Tantowijoyo, E. Arguni, M. R. Ansari, E. Supriyati, D. S. Wardana, Y. Meitika, I. Ernesia, I. Nurhayati, E. Prabowo, B. Andari, B. R. Green, L. Hodgson, Z. Cutcher, E. Rancès, P. A. Ryan, S. L. O’Neill, S. M. Dufau, New England Journal of Medicine, 384:2177-2186. 2021-06-10 11:05:41.
BACKGROUND Aedes aegypti mosquitoes infected with the wMel strain of Wolbachia pipientis are less susceptible than wild-type A. aegypti to dengue virus infection. METHODS We conducted a cluster-randomized trial involving releases of wMel-infected A. aegypti mosquitoes for the control of dengue in Yogyakarta, Indonesia. We randomly assigned 12 geographic clusters to receive deployments of wMel-infected A. aegypti (intervention clusters) and 12 clusters to receive no deployments (control clusters). All clusters practiced local mosquito-control measures as usual. A test-negative design was used to assess the efficacy of the intervention. Patients with acute undifferentiated fever who presented to local primary care clinics and were 3 to 45 years of age were recruited. Laboratory testing was used to identify participants who had virologically confirmed dengue (VCD) and those who were test-negative controls. The primary end point was symptomatic VCD of any severity caused by any dengue virus serotype. RESULTS After successful introgression of wMel into the intervention clusters, 8144 participants were enrolled; 3721 lived in intervention clusters, and 4423 lived in control clusters. In the intention-to-treat analysis, VCD occurred in 67 of 2905 participants (2.3%) in the intervention clusters and in 318 of 3401 (9.4%) in the control clusters (aggregate odds ratio for VCD, 0.23; 95% confidence interval [CI], 0.15 to 0.35; P=0.004). The protective efficacy of the intervention was 77.1% (95% CI, 65.3 to 84.9) and was similar against the four dengue virus serotypes. The incidence of hospitalization for VCD was lower among participants who lived in intervention clusters (13 of 2905 participants [0.4%]) than among those who lived in control clusters (102 of 3401 [3.0%]) (protective efficacy, 86.2%; 95% CI, 66.2 to 94.3).
How AI and mosquito sex parties can save the world
17660D. Takahashi, Ventura Beat, 2021-06-09 19:43:52.
Jerusalem-based Diptera.ai has figured out a way to use AI to fight the growing threat of mosquitoes, which are spreading malaria and viruses like Zika, dengue, and yellow fever. While the method for fighting mosquitoes has been around for decades, AI can take it to a new level and democratize what was otherwise a very costly and localized abatement effort. We’ll get to the sex parties in a bit. Diptera.ai is using computer vision and eco-friendly technology to make it easier to control mosquito populations using the sterile insect technique, which sends sterilized male mosquitoes to mate with female mosquitoes, said Diptera.ai CEO Vic Levitin, in an interview with VentureBeat. “We think we can disrupt the $100 billion pest control market,” Levitin said, noting that many other pest control methods are toxic to both humans and the environment.
Mosquitoes armed with virus-fighting bacteria sharply curb dengue infections, hospitalizations
17319K. Servick, Science, 2021-06-09 11:55:26.
A strategy for fighting dengue fever with bacteria-armed mosquitoes has passed its most rigorous test yet: a large, randomized, controlled trial. Researchers reported today dramatic reductions in rates of dengue infection and hospitalization in areas of an Indonesian city where the disease-fighting mosquitoes were released. The team expects the World Health Organization (WHO) to formally recommend the approach for broader use. The findings are a “breakthrough” that brings the approach “much closer to … being an official strategy to control dengue,” says Ewa Chrostek, an infection biologist at the University of Liverpool who was not involved with the work. WHO estimates there are 100 million to 400 million infections per year with dengue, which can cause high fever and severe joint pain. The bacterium Wolbachia pipientis naturally inhabits many insects, though not Aedes aegypti mosquitoes, the main transmitter of dengue virus. In A. aegypti cells, the bacterium can block viruses, including dengue, from replicating, making the insects less likely to spread disease when they bite humans. That has made the microbe a promising strategy for fighting dengue. In tropical regions, where mosquito-borne viruses are common, other strategies such as insecticides have failed to fully control the disease.
Study demonstrates ‘exciting potential’ of Wolbachia-infected mosquitoes to control dengue
17313G. Gallagher, Healio, 2021-06-09 11:43:08.
The release of Wolbachia-infected mosquitoes led to a 77% reduction in the incidence of symptomatic dengue in an Indonesian city, according to researchers, who said the same approach could be used to fight other mosquito-borne diseases. The study tested a strain of Wolbachia pipientis called wMel that makes Aedes aegypti mosquitoes less susceptible to dengue virus infection. Wolbachia pipientis occurs naturally in many insects but not A. aegypti, the primary vector of dengue, according to Adi Utarini, PhD, MPH, MSc, and colleagues from the nonprofit World Mosquito Program, which has been releasing Wolbachia-infected mosquitoes in the wild since 2011. A study in Indonesia demonstrated the potential of a natural intervention to significantly reduce the incidence of dengue, the world’s most prevalent mosquito-borne disease. “Wolbachia facilitates its own population introgression by manipulating reproductive outcomes between wild-type and Wolbachia-infected mosquitoes: the only viable mating outcomes are those in which the progeny are infected with Wolbachia,” they wrote in the new report, which was published Wednesday in The New England Journal of Medicine.
‘Nigeria has capacity for safe application of modern biotechnology’
17298M. Adewale, The Guardian, 2021-06-09 11:00:41.
Director-general of the National Biosafety Management Agency (NBMA), Dr. Rufus Ebegba, has declared that Nigeria has the capacity to deploy safe biotechnology products for agricultural development and environmental safety. Ebegba, who gave the assurance at the opening of a two-day retreat on agricultural biotechnology for media practitioners and extension workers yesterday in Kano, explained that Nigeria possessed the institutional capacity and policy framework to ensure the application of modern technology, especially on agricultural production with the potential to accelerate food security and reduce import dependency. He stressed that the establishment of the NBDA, which necessitated the development of national policy on biotechnology in 2001 and the enactment of the agency, mandated to ensure the safety of modern biotechnology products, has positioned the country with the knowledge to deploy Genetically Modified Organisms (GMOs) products. Ebegba stressed that part of the core responsibility of NBDA was to ensure the regulation of biotechnology and the safety of GMO products for human health and the environment.
Gene tech to prevent crossbreeding could safely harness the power of gene drives
17212I. l. Guillou, The Science Advisory Board, 2021-06-04 15:52:06.
A new gene engineering technology could allow scientists to harness the benefits of releasing genetically modified animals into the wild without the risk of uncontrolled spread. The new study, published in the journal Nature Communications on June 2, could help in the battle against the spread of diseases like malaria. The advent of the genetic age offers the tantalizing prospect of being able to genetically alter animals, such as pests and disease vectors, to reduce the harm they cause to society. However, any technology with the ability to make a difference on a significant scale would also have the potential to cause serious damage if it went out of control. Gene drives are one such technology. These genetic modifications are designed to spread through a population quickly and rely on the CRISPR-Cas9 gene editing system to make a duplicate copy of the gene drive on the partner chromosome. This means that all offspring inherit the gene, compared to only 50% through normal genetic inheritance. However, there are concerns about the effect of releasing such gene drives into the wild. Unintended consequences, potentially due to mutations or ecological shifts, could be irreversible. This has led geneticists to search for new versions of gene drives that can prevent unrestricted spread by stopping engineered animals from crossbreeding with the wild population. Approaches previously developed have severe limitations, such as not working in multicellular organisms, causing high fitness costs, or working incompletely.
Australia plots biological warfare to eradicate rampaging ‘mouse plague’
17204J. Smyth, Financial Times, 2021-06-03 15:37:11.
Australia is home to some of the world’s most fearsome creatures. But none is more destructive than the humble house mouse, a plague of which is rampaging across vast swaths of farmland and terrorising countryfolk. Farmers in New South Wales, the worst affected state, warned the furry critters could cost them A$1bn ($765m) in lost crops and poison baits this season. Residents in rural towns have been fighting a six-month battle against the army of wild house mice, which has gnawed through wiring on home appliances, polluted water supplies and even bitten patients in hospital beds. Scientists said the plague was bolstered by favourable weather conditions after years of drought and the nation’s second biggest grain harvest on record. State authorities have proposed “napalming” the mice by allowing farmers to use the poison bromadiolone against the mice, which has ignited a furious debate over its environmental impact.
Mouse plague control hopes raised with funding for genetic biocontrol research
17289Anonymous, From Press, 2021-06-03 10:36:25.
As communities and farmers continue to battle the mouse plague, a funding announcement for genetic biocontrol research could be a potential game changer for future plagues. The New South Wales government has today announced a $50 million mouse control package which includes $1.8 million dollars in funding for genetic control of mice populations. The project aims to fast-track the delivery of next generation "gene drive" technology to control plagues of the future. Researchers have welcomed the announcement, including Australia's lead researcher Professor Paul Thomas from the University of Adelaide. He said the technology is only relatively new, having been developed to some extent for insects and malaria control, but has not yet been applied to mammals. "So effectively it just uses the natural mating processes to spread a gene though a population that will cause, [and] what we are trying to cause, female [mouse] infertility," he said. "We have modelled it already and that should cause the population to crash over time. "This boost of funding will enable us to move much faster on these projects."Another control approach will also be investigated, the "X-shredder" approach, which eliminates sperm carrying the X chromosome, producing more male than female offspring.
Mutant mosquitoes carrying ‘death gene’ released as ‘bio-engineered’ insects terrify
17185J. Caven, Daily Star, 2021-06-02 20:16:02.
Mutant mosquitoes which carry a ‘death gene’ have been released into the skies in a bid to curb diseases from spreading to humans. Tens of thousands of genetically modified male insects will mate with female Aedes aegypti mosquitoes, which transmit illnesses, in Florida Keys, US. Although the males don’t bite, they carry a gene which passes on and kills female offspring in the early larval stages. The pilot project aims to wipe out a generation of potential disease-carriers. Scientists say usual methods to stop the spread of disease from mosquitoes are becoming less effective due to resistance. But critics have slammed the programme and say they are being used as “guinea pigs in a sci-fi experiment”, the Times reported.
‘Death gene’ in genetically modified male mosquitoes
17181J. Goddard, The Times, 2021-06-02 20:10:43.
Tens of thousands of bio-engineered mosquitoes have taken flight in the Florida Keys under a pilot project that aims to breed insects programmed with a “death switch”. Genetically modified males produced by Oxitec — a British-founded biotechnology company — have begun mating with local populations of invasive Aedes aegypti mosquitoes, whose female progeny are programmed to die before they mature, wiping out a generation of potential disease-carriers. “Mosquito-borne disease is a very real issue and conventional controls are losing their effectiveness,” said Dr Nathan Rose, head of regulatory affairs at Oxitec in Milton Park, Oxfordshire.
Synthetic SPECIES developed for use as a confinable gene drive
17179University of California - San Diego, ScienceDaily, 2021-06-02 20:04:29.
CRISPR-based technologies offer enormous potential to benefit human health and safety, from disease eradication to fortified food supplies. As one example, CRISPR-based gene drives, which are engineered to spread specific traits through targeted populations, are being developed to stop the transmission of devastating diseases such as malaria and dengue fever. But many scientists and ethicists have raised concerns over the unchecked spread of gene drives. Once deployed in the wild, how can scientists prevent gene drives from uncontrollably spreading across populations like wildfire? Now, scientists at the University of California San Diego and their colleagues have developed a gene drive with a built-in genetic barrier that is designed to keep the drive under control. Led by molecular geneticist Omar Akbari's lab, the researchers engineered synthetic fly species that, upon release in sufficient numbers, act as gene drives that can spread locally and be reversed if desired.
‘Gene drive’ tech to control mice plagues
17219AAP, Countryman, 2021-06-02 16:11:50.
As western NSW deals with a devastating mouse plague the government is investing in breakthrough genetic biocontrol research that could transform pest management in Australia. Agriculture Minister Adam Marshall said the NSW government would provide $1.8 million to the project to fast-track the delivery of next generation 'gene drive' technology to control future plagues. "The government has invested $50 million in a range of support measures, not only to mitigate the impacts of the mice currently crawling across so much of NSW, but also to create options to ensure we reduce the impact of future population spikes," he said on Thursday. Until now farmers have had to rely on baiting and trapping to control mouse infestations but the government was now "fast-tracking critical research to bring mouse control into the 21st century", he said. The three-year program of genetic biocontrol research will identify fast acting gene drives which are designed to spread an inherited characteristic through a population at higher-than-normal rates. Mr Marshall said it would also investigate the transferability of the technology to other pest species such as black rats, rabbits and feral cats using advanced computer modelling.
Improving mosquito control strategies with population genomics
18781T. L. Schmidt, N. M. Endersby-Harshman and A. A. Hoffmann, Trends in Parasitology, 37:907-921. 2021-05-29 12:41:38.
Mosquito control strategies increasingly apply knowledge from population genomics research. This review highlights recent applications to three research domains: mosquito invasions, insecticide resistance evolution, and rear and release programs. Current research trends follow developments in reference assemblies, either as improvements to existing assemblies (particularly Aedes) or assemblies for new taxa (particularly Anopheles). With improved assemblies, studies of invasive and rear and release target populations are better able to incorporate adaptive as well as demographic hypotheses. New reference assemblies are aiding comparisons of insecticide resistance across sister taxa while helping resolve taxon boundaries amidst frequent introgression. Anopheles gene drive deployments and improved Aedes genome assemblies should lead to a convergence in research aims for Anopheles and Aedes in the coming years.
WHO releases new guidance for deployment of genetically modified mosquitoes
17130E. Henderson, News Medical Life Sciences, 2021-05-28 19:13:57.
The World Health Organization (WHO) has released new guidance for the deployment of genetically modified (GM) mosquitoes to combat vector-borne diseases like malaria and dengue. GM mosquitoes may carry a gene that kills female progeny and the technology can be used against the Aedes aegypti mosquito that carries dengue, chikungunya and Zika viruses. For malaria, genetic modification has focused on reducing the ability of the female Anopheles mosquito to carry the parasite that causes the disease. The WHO guidance, released this month, relates to research and development of GM mosquitoes as well as issues around effectiveness, safety, affordability and ethics. Presently, measures against mosquito vectors include the use of insecticides and elimination of the breeding spots of mosquito larva, said the guidance, developed in partnership with WHO collaborators such as the Special Programme for Research and Training in Tropical Diseases and the GeneConvene Global Collaborative.
Mosquitoes are deadly pests, genetically-modified mosquitoes could help stop disease
17127T. Browne, ClickOrlando, 2021-05-27 19:04:12.
Hearing the words “genetically modified mosquitoes” can sound like the plot for a science-fiction movie but Meredith Fenson, a native Floridian turned biological pest control specialist says, “mosquitoes are the world’s deadliest animal by far” and a study happening right now in the Florida Keys could help change the tide. Fenson works as the head of global public affairs for Oxitec and sat down with News 6 anchors Matt Austin and Ginger Gadsden on Florida’s Fourth Estate podcast to talk about how genetically modified mosquitoes work, concerns surrounding their release and Oxitec’s plans to release more in the future. Aedes Aegypti, the yellow fever mosquito, only makes up about 4% of the population in the Florida Keys but Fenson says they are responsible for virtually all the diseases spread from mosquitoes to humans. She says this includes Zika, dengue fever and Chikungunya.
A Novel Genetic Sexing Strain of Anastrepha Ludens for Cost-Effective Sterile Insect Technique Applications: Improved Genetic Stability and Rearing Efficiency
17125E. Ramírez-Santos, P. Rendon, G. Gouvi, A. Zacharopoulou, K. Bourtzis, C. Cáceres and K. Bloem, Insects, 12. 2021-05-27 19:00:07.
Anastrepha ludens (Loew) is one of the most destructive insect pests damaging several fruits of economic importance. The sterile insect technique (SIT) is used under an area-wide integrated pest management approach, to suppress these pest populations. Mass rearing facilities were initially established to produce sterile males of bi-sexual strains in support of SIT. The first genetic sexing strain (GSS) for A. ludens, Tapachula-7, based on pupal color dimorphism, was a key development since the release of males-only significantly increases the SIT efficiency. In this study, we document the development of a novel pupal color-based GSS. Twelve radiation-induced translocation lines were assessed as potential GSS in terms of recombination rates and rearing efficiency at a small scale. The best one, GUA10, was cytogenetically characterized: it was shown to carry a single translocation between the Y chromosome and chromosome 2, which is known to carry the black pupae marker. This GSS was further evaluated at medium and large scales regarding its genetic stability, productivity and quality versus Tapachula-7. GUA10 presented better genetic stability, fecundity, fertility, production efficiency, flying ability, and male mating, clear indicators that GUA10 GSS can significantly improve the efficacy and cost-effectiveness of SIT applications against this pest species.
Genetic engineering may help control disease-carrying mosquitoes
17123Anonymous, The Economist, 2021-05-26 18:56:02.
EVERY YEAR, hundreds of millions of people catch mosquito-borne diseases like malaria and dengue fever. Hundreds of thousands die. Drug treatments are imperfect. And, despite decades of effort, vaccines have, for many of these diseases, proved tricky to perfect. Better, then, to stop those infections happening in the first place, by exterminating—or at least suppressing—the mosquitoes that carry the diseases. In a paper just published in the Proceedings of the National Academy of Sciences, a team of researchers led by Craig Montell, of the University of California, Santa Barbara, describe how CRISPR-Cas9, a new and powerful genetic-engineering process, could help to do just that. Dr Montell and his colleagues used CRISPR to boost an existing control method called the sterile insect technique (SIT). This involves releasing lots of sterilised males into the wild. Females that mate with these males produce no offspring. Repeated releases can reduce populations dramatically. SIT has been used in North America to eliminate screwworm flies, an agricultural pest, and to suppress several species of crop-munching fruit flies.
Suppression of female fertility in Aedes aegypti with a CRISPR-targeted male-sterile mutation
17112J. Chen, J. Luo, Y. Wang, A. S. Gurav, M. Li, O. S. Akbari and C. Montell, Proceedings of the National Academy of Sciences, 118:e2105075118. 2021-05-26 18:33:06.
We introduced and characterized the impact on female fertility of an Ae. aegypti mutation that disrupts a gene that is specifically expressed in testes. We used CRISPR/Cas9 to generate a null mutation in the Ae. aegypti β2-tubulin (B2t) gene, which eliminates male fertility. When we allowed wild-type females to first mate with B2t mutant males, most of the females did not produce progeny even after being subsequently exposed to wild-type males. We also introduced B2t mutant and wild-type males simultaneously with wild-type females and found that a larger number of B2t mutant males relative to the wild-type males was effective in significantly suppressing female fertility. These results raise the possibility of employing B2t sterile males to improve the efficacy of SIT in suppressing populations of Ae. aegypti through repeated releases and thereby reduce the transmission of viruses by these invasive mosquitoes.All study data are included in the main text.
Oxitec takes on growing cattle tick challenges
17119Annonymous, The Cattle Site, 2021-05-25 18:50:21.
Oxitec Ltd, the leading developer of biological solutions to control pests that transmit disease, destroy crops and harm livestock, announced that the Bill & Melinda Gates Foundation has awarded a grant for a feasibility project to develop an Oxitec self-limiting solution for the disease-spreading cattle tick, Rhipicephalus microplus. As part of this grant, Oxitec will work with Clinglobal, one of the world’s largest science-based animal health service providers, incorporating Clinglobal’s deep and industry-leading expertise in animal vector control practices. As a species-specific approach to controlling pests, Oxitec’s Friendly technology platform offers a safe, environmentally friendly, and sustainable solution, proven to significantly reduce target pest populations to very low levels. A future Friendly cattle tick solution would reduce reliance on pesticides and offer cattle farmers a new way of protecting the health of their animals without the use of chemical pesticides.
Pest reduction with female killers and sterile males
17114L. Mertz, Good Fruit Grower, 2021-05-25 18:40:52.
New ways to fight spotted wing drosophila are in the works, thanks to new genetic engineering tools. These transgenic methods introduce new reproduction-hampering genes into male SWD, so that when they mate with females, the females either don’t have any young, or their female young die early in their development. The approach falls under the umbrella of sterile insect technique (SIT), which has traditionally been done with radiation to sterilize males that are then released to reduce pest reproduction. “SITs are thought of as green technologies, because they are species-specific, they have the advantage that the control agent is the insect itself, and they reduce the dependence on insecticides,” said Max Scott, a professor of entomology at North Carolina State University who is developing one of these approaches. He and his research group have incorporated a female-killing gene into male SWD. In a different approach, the San Diego company Agragene is advancing technology first developed by University of California, San Diego researchers. Here, the project makes use of an advanced gene-editing tool — called CRISPR — to add genes that both kill females and sterilize males. “We really do believe that our technology will bring a sea change to what’s going on out there,” said Gordon Alton, president and CEO of Agragene Inc. If all goes well, he anticipates growers will have access to the technology within two to three years
Genetically modified mosquitoes; WHO issues new guidance for research
17084DTE Staff, Down To Earth, 2021-05-20 15:10:16.
Genetically-modified mosquitoes or GMMs have been used across the world to control mosquitoes. GMMs have been able to bring down the population of the Aedes aegypti by 90 per cent in countries like Brazil, the Cayman Islands, Panama and Malaysia. But there have never been any global protocols or standards on the breeding of GMMs. The World Health Organization has addressed this by setting essential standards for the research and development of GMMs. These standards are mainly about ethics, safety, affordability and effectiveness of GMMS. GMMs are male mosquitoes modified to carry a lethal gene. When they mate, the genes get passed on to their offspring. The gene prevents female offspring from building an essential protein and causes them to die before reaching maturity. GMMs could become a cost-effective and powerful tool to control mosquitoes. Over 40,000 people die from malaria and 100-400 million people get infected with dengue each year. They can reach mosquito populations and mosquito larval breeding sites that are currently expensive and difficult to reach. It can target specific mosquito species and thus avoid the ecological and environmental hazards of usual insecticides.
Burkina Faso Testing Genetically Modified Mosquitoes to Curb Malaria
17082H. Wilkins, Voice of America, 2021-05-20 15:06:44.
The mosquito-borne disease malaria kills more than 400,000 people each year, the vast majority in Africa. Target Malaria, an international group of scientists, is working in Burkina Faso on a genetic solution. Abdoulaye Diabate, with the West African country’s Research Institute for Science and Health, said the objective of Target Malaria is to develop a genetic control tool specifically applied to mosquitoes to be able to drastically reduce or eliminate the density of mosquitoes. The scientists are genetically modifying mosquitoes so their offspring will be only male, and any females they mate with after release will also produce just males. Since only female mosquitoes spread malaria, the disease should drop off quickly along with their population. In village of Bana, where the genetically modified mosquitoes were first tested in 2019, locals were initially worried about the experiment. Kiesiara Sanou, a Bana village elder, said that at the beginning, people thought the survey would release mosquitoes in the village that could cause more diseases. But since working with Target Malaria, they’ve come to understand exactly what the purpose is and now even help them with tasks like collecting the mosquitoes. Genetically modified mosquitoes are just one malaria solution that has been tested in Burkina Faso. The country also pioneered pesticide-infused mosquito nets.
Florida Environmental Group Says GMO Mosquitoes Fall Short on Scientific Rigor
17079C. Drukier, NTD, 2021-05-20 15:01:00.
America’s first genetically modified mosquitoes are now buzzing around six locations in the Florida Keys as part of a pilot project. Developed by UK biotech company Oxitec, the bugs are designed to kill off the wild population of Aedes aegypti mosquitoes that carry diseases like Dengue fever, yellow fever, and the Zika virus. Some people who live in the Keys aren’t happy about being part of a science experiment. Barry Wray, executive director of the Florida Keys Environmental Coalition explains why his organization has been fighting the GMO bugs for the last decade.
WHO issues new guidance for research on genetically modified mosquitoes to fight malaria and other vector-borne diseases
17076WHO, reliefweb, 2021-05-19 14:55:10.
New guidance from the World Health Organization (WHO) sets essential standards to inform future research and development on genetically modified mosquitoes, particularly in addressing issues relating to ethics, safety, affordability and effectiveness. Malaria and other vector-borne diseases, including dengue and Zika, affect millions globally. More than 400 000 people a year die from malaria alone. If proven safe, effective and affordable, genetically modified vector mosquitoes could be a valuable new tool to fight these diseases and eliminate their enormous health, social and economic burden. The guidance framework for testing genetically modified mosquitoes, developed in partnership with TDR, the Special Programme for Research and Training in Tropical Diseases, and the GeneConvene Global Collaborative, an initiative of the Foundation for the National Institutes of Health, describes best practices to ensure that the study and evaluation of genetically modified mosquitoes as public health tools is safe, ethical and rigorous. Current strategies for limiting transmission of mosquito-borne diseases are only partially effective. New, complementary approaches are needed to close the gaps in current vector control interventions, such as effective control of outdoor biting, and to provide alternatives to manage the increasing threat of insecticide resistance. Research suggests genetically modified mosquitoes could be a powerful and cost-effective tool to supplement existing interventions.
Guidance framework for testing of genetically modified mosquitoes, second edition
17049WHO, WHO-TDR, 2021-05-19 10:41:03.
For more than 2 decades, scientists have been working to harness the promise of molecular biology to develop genetically modified mosquitoes (GMMs) for use as public health tools to prevent the transmission of vector-borne diseases. Responding to a need for additional standards and guidance, the WHO Special Programme for Research and Training in Tropical Diseases (WHO-TDR) and the Foundation for the National Institutes of Health (FNIH) published in 2014 the first WHO Guidance framework for testing genetically modified mosquitoes. This revised version takes into account the technical progress made and lessons learned in this rapidly advancing field of research. Like the original guidance framework, it is intended to provide standards that foster quality and consistency in the processes for developing, testing and regulating these new genetic technologies. Best practices recommended in the 2021 guidance framework will further contribute to the comparability of results and credibility of conclusions in order to facilitate decision-making by countries interested in the potential use of GMMs as public health tools for the control of vector-borne diseases.
Small-Cage Laboratory Trials of Genetically-Engineered Anopheline Mosquitoes
17068R. Carballar-Lejarazú, T. B. Pham, V. Bottino-Rojas, A. Adolfi and A. A. James, J Vis Exp, 2021-05-18 14:30:01.
Control of mosquito-borne pathogens using genetically-modified vectors has been proposed as a promising tool to complement conventional control strategies. CRISPR-based homing gene drive systems have made transgenic technologies more accessible within the scientific community. Evaluation of transgenic mosquito performance and comparisons with wild-type counterparts in small laboratory cage trials provide valuable data for the design of subsequent field cage experiments and experimental assessments to refine the strategies for disease prevention. Here, we present three different protocols used in laboratory settings to evaluate transgene spread in anopheline mosquito vectors of malaria. These include inundative releases (no gene-drive system), and gene-drive overlapping and non-overlapping generation trials. The three trials vary in a number of parameters and can be adapted to desired experimental settings. Moreover, insectary studies in small cages are part of the progressive transition of engineered insects from the laboratory to open field releases. Therefore, the protocols described here represent invaluable tools to provide empirical values that will ultimately aid field implementation of new technologies for malaria elimination.
Genetic Technologies for Sustainable Management of Insect Pests and Disease Vectors
17157S. Grilli, R. Galizi and C. Taxiarchi, Sustainability, 13. 2021-05-18 11:00:25.
Recent advancements in genetic and genome editing research, augmented by the discovery of new molecular tools such as CRISPR, have revolutionised the field of genetic engineering by enabling precise site-specific genome modifications with unprecedented ease. These technologies have found a vast range of applications, including the development of novel methods for the control of vector and pest insects. According to their genetic makeup and engineering, these tools can be tuned to impose different grades of impact on the targeted populations. Here, we review some of the most recent genetic control innovations under development, describing their molecular mechanisms and performance, highlighting the sustainability potentials of such interventions.
Sterile Insect Technique: Successful Suppression of an Aedes aegypti Field Population in Cuba
17151R. Gato, Z. Menendez, E. Prieto, R. Argiles, M. Rodriguez, W. Baldoquin, Y. Hernandez, D. Perez, J. Anaya, I. Fuentes, C. Lorenzo, K. Gonzalez, Y. Campo and J. Bouyer, Insects, 12:13. 2021-05-18 10:40:50.
Here, we describe an open field trial to evaluate the effect of the release of irradiated male Ae. aegypti on a wild population. The pilot trial was carried out in a suburb of Havana and compared the mosquito population density before and after the intervention, in both untreated control and release areas. The wild population was monitored by an ovitrap network, recording frequency and density of eggs as well as their hatch rate. A significant amount of sterility was induced in the field population of the release area, as compared with the untreated control area. The ovitrap index and the mean number of eggs/trap declined dramatically after 12 and 5 weeks of releases, respectively. For the last 3 weeks, no eggs were collected in the treatment area, clearly indicating a significant suppression of the wild target population. We conclude that the sterile males released competed successfully and induced enough sterility to suppress the local Ae. aegypti population.
Genetically Modified Mosquitoes Take Flight to Fight Invasive Species in Florid
17073T. Machemer, Smithosonian Magazine, 2021-05-17 14:46:06.
In late April, the biotechnology company Oxitec placed blue-and-white hexagonal boxes on the properties of six private volunteers around the Florida Keys. After pouring in water, the genetically modified mosquito eggs inside activated and hatched. Now the first larvae have developed into full-grown male mosquitoes and taken flight, Susan Millis reports for Science News. About 12,000 of Oxitec’s male mosquitoes will fly out of the boxes each week for the next 12 weeks. Over several mosquito generations, Oxitec’s genetically modified Aedes aegypti could reduce the population of female mosquitoes—which bite and spread disease—and then lower the entire population in the Florida Keys in turn. The current trial marks the first time that genetically modified mosquitoes have been released to fly freely in the United States.
Genetically modified mosquitoes may help scientists swat dreaded midge
17057W. Jean, The Times, 2021-05-16 13:41:37.
Scotland’s bloodthirsty midges may finally meet their match thanks to revolutionary genetic manipulation techniques that could stop the pesky insects biting chunks out of the tourist industry. News that a British biotechnology company has created genetically modified non-biting mosquitoes in Florida to help curb dengue and yellow fever, and ultimately malaria, may give hope in the fight against the annual Scottish scourge. Oxford-based Oxitec and its American partners recently released genetically modified male mosquito larvae into the Florida Keys to control the wild, disease-carrying mosquito population rather than use pesticides. While midges share some characteristics with mosquitoes, Dr Simon Carpenter, a Pirbright Institute entomologist who was part of the team that built the first complete genome of the Highland biting midge, said the gene-editing process
Bliotech firm behind CRISPR mosquitoes is working on other gene-hacked creatures
17217D. Robitzski, Futurism, 2021-05-14 16:08:11.
Brazil’s regulatory agency CTNBio gave Oxitec and Bayer the approval they needed to launch a field test of the gene-hacked armyworm — technically a caterpillar — on commercial crops, so there may be genetically altered bugs crawling across corn farms in the area soon. For years, Brazilian farmers have been trying to control fall armyworms with chemical pesticides. But as the pests grew to resist the sprays — which were already difficult to time in a way that actually impacted the nocturnal insect — they had to spray more and more harmful chemicals in the environment, according to Zenger‘s reporting. If Oxitec’s technology works — there’s reason to doubt that its similar mosquito tech does what the company claims — then that excessive pesticide spraying may be able to stop. “Our technology potentially reduces the need for additional pesticides in the long term,” Oxitec head of agricultural programs Neil Morrison said, according to Zenger. “Besides reducing populations of the pest, it also has the potential to slow the resistance development to insecticides and biotechnology enhanced crops.”
First Genetically Modified Mosquitoes Released in U.S. Are Hatching Now
17046D. Coffey, Scientific American, 2021-05-14 11:50:11.
This week, mosquito eggs placed in the Florida Keys are expected to hatch tens of thousands of genetically modified mosquitoes, a result of the first U.S. release of such insects in the wild. A biotechnology firm called Oxitec delivered the eggs in late April as part of a federally approved experiment to study the use of genetic engineering—rather than insecticides—to control disease-carrying mosquito populations. The move targets an invasive species, called Aedes aegypti, that carries Zika, dengue, chikungunya, yellow fever and other potentially deadly diseases, some of which are on the rise in Florida. The experiment relies on a genetic alteration that will be lethal to a large number of future offspring. In this case, male mosquitoes have been modified to carry a gene that makes their female progeny dependent on the antibiotic tetracycline—and thus fated to die in the wild. As the mating cycle repeats over generations, female numbers are depleted, and the population is suppressed. The modified insects eventually die off, making this approach self-limiting. Oxitec overcame significant regulatory hurdles before getting the go-ahead from the U.S. Food and Drug Administration in 2016 and then the Environmental Protection Agency in 2020. If the current pilot effort is successful, the firm is set to release as many as 20 million more males in the prime of Florida’s mosquito season later this year. The results of the experiment could ultimately help address concerns about releasing genetically modified organisms into the wild.
In a World-First, Genetically Modified Mosquitoes Are Hatching in the US
17044B. Bergan, INTERSTING ENGINEERING, 2021-05-14 11:44:58.
Mosquito eggs placed in the Florida Keys are about to hatch tens of thousands of genetically altered mosquitos, the first such release of "synthetic" insects in the world, according to an initial report from Scientific American. Pilot program for genetically modified mosquitoes could see millions more released this year. The biotechnology firm called Oxitec delivered the modified mosquito eggs late in April as part of a federally-endorsed experiment to study the use of genetic engineering, as opposed to insecticides, to control the populations of illness-spreading mosquitoes. This project targets one specific species of mosquito called Aedes aegypti, known to carry Zika, chikungunya, yellow fever, dengue, and other possibly deadly diseases. And some of these diseases have been on the rise in Florida. The new genetic contribution given to the mosquitoes will be deadly to many future offspring, with males altered to carry a gene causing female offspring to become dependent on the antibiotic called tetracycline — which is a death sentence for the female mosquitoes. After several generations, there won't be enough female mosquitoes of the species to maintain population numbers, putting a ceiling on them. But this is a temporary measure, since the genetically modified male mosquitoes will eventually all die.
The U.S.’s first open-air genetically modified mosquitoes have taken flight
17041S. Milius, Science News, 2021-05-14 11:35:37.
The first genetically modified mosquitoes that will be allowed to fly free outdoors in the United States have started reaching the age for mating in the Florida Keys. In a test of the biotech company Oxitec’s GM male mosquitoes for pest control, these Aedes aegypti started growing from tiny eggs set out in toaster-sized, hexagonal boxes on suburban private properties in late April. On May 12, experiment monitors confirmed that males had matured enough to start flying off on their own to court American female mosquitoes. This short-term Florida experiment marks the first outdoor test in the United States of a strain of GM male mosquitoes as a highly targeted pest control strategy. This strain is engineered to shrink local populations of Ae. aegypti, a mosquito species that spreads dengue and Zika (SN: 7/29/16). That could start happening now that the GM mosquitoes have reached mating age because their genetics makes them such terrible choices as dads.
Use of genetically modifed mosquitoes to minimize the burden of diseases casused by mosquitoes in South Texas.
17016MDN Staff, MegaDoctor News, 2021-05-11 13:00:04.
Of the many species of mosquitoes, female Aedes aegypti is the primary vector that is responsible for transmission of several diseases and has been most extensively studied. The efforts of the World Health Organization and the Center for Disease Control and Prevention to prevent and/or control mosquito-borne illness have yielded success, but it remains a serious global challenge. More recently, several approaches to create transgenic mosquitoes with the ultimate objective of preventing and/or controlling mosquito-borne illness have undergone field studies. Infecting mosquitoes with different strains of Wolbachia resulted in the reduction of egg laying rates, transmission ability and shorter lifespan. Similarly, using genetic technology, a self-limiting strain of male mosquitoes (OX513A) when released in the field have shown an 81%-95% suppression of population of this strain as compared to adjacent no-release control field. These encouraging results prompted the issuance of authorization by the U.S. Environmental Protection Agency for the use of second generation genetically modified mosquitoes (OX5034) in Florida and Texas” said Sohail Rao, MD, MA, DPhil, President and Chief Executive Officer, DHR Health Institute for Research & Development. As the first-ever use of genetically modified mosquitoes in the United States, over 750 million OX5034 will be ultimately released in the Florida Keys an area devastated by mosquito-borne illnesses
Monster Mosquito–Why the Technology of Genetically Modified Mosquitoes is Dangerous and Should Be Stopped Worldwide
17001B. Dogra, counter currents, 2021-05-10 15:32:17.
After sparking controversy in other countries including India, the technology of genetically engineered mosquitoes is now leading to widespread protests in Florida USA. Here the biotechnology giant company Oxitec in collaboration with local officialdom is moving ahead with a pilot project to release millions of genetically engineered mosquitoes in Monroe County over a period of two years or so. The stated aim is to control the population of Aedes aegypti, a species that can carry both the dengue and the yellow fever virus. The idea is for genetically altered male, non-biting mosquitoes to mate with local , biting females , producing offspring that die at larval stage. Pointing out the inherent dangers of such technologies a spokesperson of Florida Key Environmental Coalition said that everyone should be writing to the White House to stop the release, at least until regulations to protect people are in place. Friends of the Earth has commented—scientists have raised concerns that genetically engineered mosquitoes could create hybrid wild mosquitoes which could worsen the spread of mosquito borne diseases and could be more resistant to insecticides than the original wild mosquitoes.
Florida releases genetically modified mosquitoes in hopes to reduce spread of disease
17011A. Fahim, Reuters, 2021-05-10 12:50:27.
Genetically modified mosquitoes have been released for the first time in the United States, taking flight in the Florida Keys in a pilot program intended to reduce the spread of deadly diseases such as dengue, yellow fever and the Zika virus.After an odyssey spanning more than a decade to secure regulatory approval, British-based biotechnology firm Oxitec, along with the Florida Keys Mosquito Control District (FKMCD)launched the project in hope of reducing the Aedes aegypti species that spread the diseases.While Oxitec and local authorities have high hopes for the program, local residents and environmental groups worry that not enough is known about the long-term effects of the new technology.Nevertheless, the Environmental Protection Agency granted an experimental use permit (EUP) to Oxitecon May 1.A half-dozen boxes containing the OX5034 mosquito created by Oxitec have been deployed in the Florida Keys, an archipelago stretching 120 miles (195 km) off the southern tip of the state.Only female Aedes aegypti bite and spread disease, so Oxitec has created males that pass on a gene that kills female offspring before they mature. Their male offspring then continue mating and passing on the altered gene.
Why Florida is releasing genetically modified mosquitoes
16999M. Murphy, The Telegraph, 2021-05-09 15:19:45.
The thousands of lab-grown mosquitoes hatching in humid gardens across Florida’s tropical Key West next week will be blissfully ignorant of the controversy they have caused. Billboards have already begun appearing near busy motorways in protest of their arrival, with one splashed with the words “risky, unnecessary, unwanted” aside a giant picture of the blood-thirsty insect. “The word ‘genetically modified’ scares people,” says Douglas Mader, a local vet and newspaper columnist living in the Lower Keys. “They think oh my god, they’re releasing genetically modified organisms (GMOs) and they are going to bite me and I’m going to turn into a zombie”. The creatures are the creation of Oxitec, a Bill Gates-backed biotechnology company based in Abingdon, Oxfordshire. Grey Frandsen, its chief executive, and around 20 scientists at Oxitec’s labs, have made it their mission to stop the spread of diseases such as dengue, Zika and malaria by controlling mosquitoes’ reproduction.
Genetically Modified Mosquitoes Have Come to the U.S. Will They Work?
16996A. de la Garza, TIME, 2021-05-09 15:13:05.
“Our Mosquito Project Takes Flight,” reads a baby-blue billboard off US-1 in the Florida Keys, alongside an image of an insect tracing a path in the shape of a heart. Sponsored by the local mosquito control board and U.K.-based biotech firm Oxitec, the ad promotes a contentious plan to release millions of genetically modified Aedes aegypti mosquitoes here to test a new method of bioengineered pest control. It’s the first-ever such experiment in the United States, and one that has turned this chain of sun-soaked island communities into a battleground over scientific truth, government authority, and humanity’s right to modify nature. Even this bit of roadside signage is contested. Four months ago, the billboard carried a different ad, paid for by the Coalition Against GMO Mosquitoes, an organization with the mission of stopping releases of the genetically modified insects in the U.S., “WARNING!!!,” it read then, “GENETICALLY MODIFIED MOSQUITOES TO BE RELEASED IN THE KEYS!!” That release began in late April, when, after a decade of planning, regulatory review and debate, Oxitec workers and local mosquito control personnel added water to a dozen plastic boxes containing the company’s “Friendly™” mosquito eggs in six locations around the Keys, triggering their hatching process. Oxitec’s Aedes aegypti mosquitoes—which the U.S. Environmental Protection Agency (EPA) approved for use last year—are genetically modified to include a “self-limiting” gene that produces a fatal protein. The mosquitoes are raised in a laboratory in the presence of tetracycline, an antibiotic that prevents the added gene from activating. The mosquitoes’ eggs are then left to hatch in the wild, without the antibiotic. The gene kills immature egg-laying females—the only ones that bite—but the males reach maturity, mate with wild females, and pass on their faulty gene. Then their female progeny die, causing the bloodsuckers’ population to crash.
Bill Gates finances the creation of transgenic mosquitoes
16992Explica.co, explica, 2021-05-07 15:03:11.
Male mosquitoes (they do not bite. They feed on nectar, not blood) from Oxitec will emerge from release boxes placed in six locations in the Florida Keys to mate with local female mosquitoes (they do bite. They do feed on blood). The female offspring from these encounters cannot survive, and the Aedes aegypti population will be controlled in this way.. The Aedes aegypti mosquito makes up about four percent of the mosquito population in the Keys. The project has the approval of the Environmental Protection Agency (EPA) and the Florida Department of Agriculture and Consumer Services (FDACS) and the collaboration of the Florida Keys Mosquito Control District (FKMCD). In 2021, the United States expects the release of 750 million transgenic mosquitoes. “An important part of the FKMCD’s mission is to protect the residents of the Florida Keys from the disease-transmitting mosquito, Aedes aegypti. As we are seeing the development of resistance to some of our current control methods, we need new tools to fight this mosquito. And given the unique ecosystem we live in, those tools must be safe, environmentally friendly and specific. That’s why we collaborate with Oxitec on this project. With the full approval of the US EPA and from the Florida Department of Agriculture and Consumer Services, and with the support of the US Centers for Disease Control and an independent advisory board, we are pleased to announce that this project will be underway soon, ”says Andrea Leal, executive director of the FKMCD.
Genetically Modified Mosquitoes Released In US For First Time To Combat Disease
16985J. Van Zijl, IFL Science, 2021-05-06 16:11:16.
A landmark project, spearheaded by the biotechnology company, Oxitec, has released genetically modified mosquitos in the Florida Keys. This marks the first time that genetically modified mosquitos have been released into the wild in the US. The reason: to combat the Aedes aegypti mosquito species responsible for spreading mosquito-borne diseases such as dengue and Zika in the region. Aedes aegypti only accounts for about 4 percent of the total mosquito population in Florida keys – however, it is responsible for almost all mosquito-borne diseases to humans. Current methods to control the species, such as spraying or fogging chemical insecticides, have failed due to the species becoming resistant. So an alternative solution was needed.
Cloning wildlife and editing their genes to protect them and us.
16982H. Thomasy, NEO-LIFE, 2021-05-06 16:06:20.
In December 10, 2020, Elizabeth Ann made history just by being born. She isn’t a British royal, an American married to a British royal, a movie star’s daughter, or even human for that matter. Elizabeth Ann is a ferret—but perhaps the most famous ferret of all time. More specifically, she is the clone of a black-footed ferret named Willa who has been dead for more than 30 years. Elizabeth Ann’s momentous birth marks the first successful cloning of an endangered species native to North America (endangered species like the gaur, or Indian bison, and the mouflon, a wild sheep originally found in Corsica and Sardinia, have been cloned previously). If she can breed successfully, Elizabeth Ann will add valuable genetic diversity to the very small estimated population of around 600 remaining black-footed ferrets, which are all descended from just seven animals. But low genetic diversity isn’t the only thing standing in the way of these ferrets making a comeback. The other major threat is disease. Diseases are a huge problem for many endangered species, but, as the previous year has emphasized all too well, diseases that circulate in animals can also have disastrous consequences if they jump to humans. Genetic engineering of animals in the wild might offer us a way to protect not only our furry friends and feathered compadres, but ourselves as well. Although still in the early stages of research, scientists around the world are working on numerous projects to engineer animals to be resistant to diseases that can impact humans as well, including plague, Lyme disease, dengue fever, and Zika.
Genetically Modified Mosquitoes Released In Florida ‘Jurassic Park Experiment’
16978D. Richardson, UNILAD, 2021-05-06 15:58:18.
Mosquitos are not only annoying but they can carry disease in their bites. In response to this, a company called Oxitec has genetically modified male mosquitos to pass on a killswitch to females. It is hoped that these genetically modified pests will help stop the transmission of deadly diseases, including yellow fever, dengue and Zika virus. The Florida Keys project, which was greenlit by the US Environment Protection Agency in May 2020, has approved the release of 750 million modified mosquitos. However, at the moment only 144,000 will be released during a three-month trial period. Nonetheless, some people in the trial areas are concerned.
Gravitas: Genetically modified mosquitoes arrive in Florida
16962P. Sharma, WION, 2021-05-06 15:03:25.
Genetically engineered mosquitoes have arrived in U.S. 20 million 'modified mosquitoes' will be released in Florida to help prevent Dengue. But, Florida residents fear a 'mosquito apocalypse'
Reengineered mosquitoes released in Florida pilot program
17021S. W. Tan, The Washington Times, 2021-05-06 13:12:32.
Genetically engineered mosquitoes have been released in the U.S. for the first time in the Florida Keys, with hopes of quelling wild, disease-carrying mosquito populations in the region. British-based biotech firm Oxitec genetically engineered Aedes aegypti non-biting male mosquitoes to carry a lethal gene that gets passed onto their offspring when they mate with wild biting female mosquitoes. The offspring are unable to survive, hence controlling the population of disease-carrying species, according to the Florida Keys Mosquito Control District (FKMCD), one of the entities that approved the firm’s project. Release boxes containing the genetically engineered male mosquitoes were placed in six locations last week — two on Cudjoe Key, one on Ramrod Key and three on Vaca Key — with thousands starting to emerge this month. Around 12,000 mosquitoes are expected to emerge each week for about 12 weeks.
A natural symbiotic bacterium drives mosquito refractoriness to Plasmodium infection via secretion of an antimalarial lipase
17027H. Gao, L. Bai, Y. M. Jiang, W. Huang, L. L. Wang, S. G. Li, G. D. Zhu, D. Q. Wang, Z. H. Huang, X. S. Li, J. Cao, L. B. Jiang, M. Jacobs-Lorena, S. Zhan and S. B. Wang, Nature Microbiology, 25. 2021-05-06 11:00:53.
The stalling global progress in the fight against malaria prompts the urgent need to develop new intervention strategies. Whilst engineered symbiotic bacteria have been shown to confer mosquito resistance to parasite infection, a major challenge for field implementation is to address regulatory concerns. Here, we report the identification of a Plasmodium-blocking symbiotic bacterium, Serratia ureilytica Su_YN1, isolated from the midgut of wild Anopheles sinensis in China that inhibits malaria parasites via secretion of an antimalarial lipase. Analysis of Plasmodium vivax epidemic data indicates that local malaria cases in Tengchong (Yunnan province, China) are significantly lower than imported cases and importantly, that the local vector A. sinensis is more resistant to infection by P. vivax than A. sinensis from other regions. Analysis of the gut symbiotic bacteria of mosquitoes from Yunnan province led to the identification of S. ureilytica Su_YN1. This bacterium renders mosquitoes resistant to infection by the human parasite Plasmodium falciparum or the rodent parasite Plasmodium berghei via secretion of a lipase that selectively kills parasites at various stages. Importantly, Su_YN1 rapidly disseminates through mosquito populations by vertical and horizontal transmission, providing a potential tool for blocking malaria transmission in the field. The symbiotic bacterium Serratia ureilytica can disseminate through mosquito populations and render mosquitoes resistant to Plasmodium infection by secreting an antimalarial lipase.
First genetically modified mosquitoes released in US
16972N. Lanese, LiveScience, 2021-05-05 15:42:05.
The biotech firm Oxitec has released its genetically modified mosquitoes in the Florida Keys, with the goal of suppressing wild, disease-carrying mosquito populations in the region. This is the first time genetically modified mosquitoes have been released in the U.S. Oxitec previously released its modified Aedes aegypti mosquitoes in Brazil, the Cayman Islands, Panama and Malaysia, and the company reported that local A. aegypti populations fell by at least 90% in those locations, Live Science previously reported. A. aegypti can carry diseases such as Zika, dengue, chikungunya and yellow fever, and releasing modified mosquitoes offers a way to control the population without using pesticides. Oxitec's modified mosquitoes, all male, have been engineered to carry a lethal gene; when the modified pests mate with wild female mosquitoes, the lethal gene gets passed on to their offspring. Though the gene does not affect the males' survival, it prevents female offspring from building an essential protein and thus causes them to die before reaching maturity. Only female mosquitoes bite people (male mosquitoes exclusively drink nectar), so the modified mosquitoes and their surviving male offspring can't pass diseases to humans.
Bill Gates-backed startup releases millions of genetically modified mosquitoes
16952ENTREPRENEUR STAFF, Entrepreneur, 2021-05-04 20:35:48.
The British company Oxitec released a cloud of hundreds of millions of genetically modified mosquitoes to study how to control their reproduction and thus stop the spread of dengue, Zika, malaria, etc. As reported by Axios , the company, which is funded by the Bill and Melinda Gates Foundation , released the mosquitoes a week ago from the Florida Keys. In a statement, Oxitec explained that this experiment seeks to study ways to stop the reproduction of Aedes aegypti , the main transmitters of potentially fatal diseases. Why are Oxitec mosquitoes different? According to the company , the males in their insect cloud have a modified gene, called OX5034, that restricts the survival of the females they mate with. Thus, mosquitoes will not grow large enough to bite humans (only females consume blood; males feed on nectar). Oxitec noted that this species only represents 4% of the mosquito population in Florida, but it is the most disease-transmitting species. The startup has already released millions of modified insects around the world, including in Brazil and the Cayman Islands.
First US Field Test of GM Mosquitoes Begins in Florida
16950C. Wilcox, The Scientist, 2021-05-04 20:30:49.
he first US field test of genetically modified mosquitoes for population control has begun in Florida. Approximately 144,000 mosquitoes engineered by the UK-based biotech firm Oxitec are to be expected to be set free over the next three months, the first of up to 750 million approved for release over the next two years by the US Environmental Protection Agency. The trial aims to test whether the mosquitoes are effective at reducing populations of invasive Aedes aegypti, a species that can transmit dangerous diseases to people. The Florida Keys Mosquito Control District, which has partnered with Oxitec, has said this species makes up only 4 percent of the mosquito community in the Keys but is responsible for nearly all disease transmission and has become increasingly resistant to available pesticides, Nature reports. According to Oxitec, the modified mosquitoes are all male and carry a gene that makes female mosquitoes dependent on an antibiotic not available in the animals’ environment, thereby killing all of the male’s female offspring. Adult mosquitoes only live for a few weeks, and just the females bite, so the firm expects its modified males can spread the female-killing insert through the population and drastically reduce the number of potential disease vectors in the region. If successful, the mosquitoes could be used in place of pesticides in control efforts. A small but vocal group of Florida residents that has opposed the “mutant mosquitoes” from the get-go are continuing to seek legal action to stop it, CNN reports. Key Largo resident Mara Daly tells CNN she hopes “civil unrest happens,” and suggests residents could have their communities sprayed with pesticides in an effort to “opt out” of the trial.
The first transgenic mosquitoes were releaseed in the United States.
16947D. Davis, Prudent Press Agency, 2021-05-04 20:19:07.
After a decade of fighting for regulatory approval and public acceptance, the biotech company has released GMO mosquitoes outdoors in the United States for the first time. The experiment, which began this week in the Florida Keys, despite objections from some local critics, is testing a method for suppressing populations of wild Aedes aegypti mosquitoes, which can transmit diseases such as Zika, dengue fever, chikungunya and yellow fever mosquitoes. Oxitec, the UK-based company Abingdon that developed mosquitoes, has previously tested the insects in the field in Brazil, Panama, the Cayman Islands and Malaysia. But so far, due to a tortuous series of regulatory decisions and Florida residents’ disapproval (see “Long Road”), no GM mosquitoes have been tested in the United States, although the country had previously allowed evidence of a GM diamond. Moth (Plutella xylostella) in New York and pink worm (Pectinophora gossypiella) in Arizona, both developed by Oxitec. “When something new and revolutionary comes along, people’s immediate reaction is to say, ‘Wait,’” says Anthony James, a molecular biologist specializing in mosquito bioengineers at the University of California, Irvine. [Oxitec] Was able to conduct a trial on the ground in the United States a big problem. “
The Bill Gates Corporation, Backed by Bill Gates, Releases Thousands of Genetically Modified Mosquitoes
16975T. Meeks, Aviation Analysis, 2021-05-04 15:50:15.
British company Oxitec has launched transgenic mosquitoes in the Florida Keys, in the United States, to study how to control their reproduction and thus limit the spread of chronic diseases transmitted by insects such as dengue fever and the Zika virus. The company, funded by the Bill & Melinda Gates Foundation, announced the placement of its confined release funds, non-release funds, and quality control funds this week in six locations: two in Cudjoe Key, one in Ramrod Key, and three in Vaca Key. Why is the Oxitec mosquito different? According to the company, the males in its insect cloud carry a modified gene called OX5034, which restricts the survival of the females they mate with. As of early next month, fewer than 12,000 mosquitoes are expected to appear per week for about 12 weeks. Untreated comparison sites will be controlled with mosquito traps at Key Colony Beach, Little Torch Key, and Summerland Key. “We started looking at this a decade ago because we were in the middle of an outbreak of dengue fever in the Florida Keys,” Andrea Lyell, executive director of the Florida Keys area for mosquito control, said during a videoconference. “So we are very excited to further this partnership, and work with both Oxitec and members of the community.” Last year the Keys authorities approved the pilot project with mosquitoes Aedes aegyptiShe is not a Florida native. This insect transmits many diseases to humans, especially in the Keys island chain, where dozens of dengue cases were recorded last year.
Sterile Insect Technique Programme against Mediterranean Fruit Fly in the Valencian Community (Spain)
16965I. Plá, J. García de Oteyza, C. Tur, M. Á. Martínez, M. C. Laurín, E. Alonso, M. Martínez, Á. Martín, R. Sanchis, M. C. Navarro, M. T. Navarro, R. Argilés, M. Briasco, Ó. Dembilio and V. Dalmau, Insects, 12. 2021-05-04 15:09:26.
The Mediterranean fruit fly, Ceratitis capitata (Wied.), is an endemic pest in fruit-growing areas of the Spanish Mediterranean coast. In the Valencian Community, it represents a serious problem in the cultivation of citrus and numerous species of fruit, such as peach, cherry, apricot, persimmon, etc. For over 50 years, the Department of Agriculture of Valencia has led, promoted, and carried out a C. capitata control programme to protect crops, especially citrus fruits, because this community is the largest national producer and the leading region for fresh citrus exports in the world. Traditionally, pest control has been based on the use of insecticides. However, a reduction of more than 90% of a target wild population was achieved in the frame of a pilot integrated pest management (IPM) project based on the sterile insect technique (SIT), which was implemented from 2003 to 2006. Based on this successful result, in 2007 the Department of Agriculture of Valencia initiated an area-wide integrated pest management (AW-IPM) programme for the suppression of C. capitata, using the SIT as the primary control method. Complementary activities are implemented periodically in hotspots and during different time periods depending on the pest population dynamics. As a result, there has been a reduction of more than 90% in the use of insecticides by aerial means to control C. capitata, as well as a growth trend in exports of citrus and fresh fruits from the Valencian Community in recent years. This paper provides a historical review of the Valencian programme and briefly describes how technological innovations and decision-making tools have contributed to programme efficiency.
Next gen insect control
16960E. Unglesbee, Progressive Farmer, 2021-05-04 14:58:12.
Dubbed "self-limiting" insects by their makers, a UK-based biotechnology company called Oxitec, these insects are genetically modified (GM) with an inserted gene that permits only male offspring to survive. Once released into a pest community, the GM insects gradually lower the population, accomplishing a new type of pest control. Then, rather politely, they die off themselves. "After we stop releasing the self-limiting males, the gene declines in a population over a short period of time and within a few generations, disappears," Neil Morrison, head of agriculture programs for Oxitec, told DTN. "It's a gene that prevents survival of half its carriers -- the females -- so it's essentially programmed to decline and disappear quite rapidly." Sound too sci-fi to be real? It's actually happening right now, in the Florida Keys. After gaining EPA and state regulatory approval for the project last year, Oxitec is working with the Florida Keys Mosquito Control District to deploy the country's first largescale release of Oxitec's self-limiting Aedes aegypti mosquitoes.
Stable isotopes for reliable identification of wild and mass-reared Queensland fruit flies in sterile insect technique programs
17031B. Mainali, A. S. Andrew, P. W. Taylor and P. Rempoulakis, Journal of Pest Science, 14. 2021-05-04 11:12:25.
Queensland fruit fly is one of the most economically important horticultural pests in Australia. Sterile insect technique (SIT) is now being reconsidered and upscaled to combat this pest so reliable discrimination of released sterile Q-flies from wild flies in monitoring traps is important for effective SIT operations. Stable isotopes provide a permanent chemical marker to discriminate sterile and wild flies when dye marking is unclear. In this study, we compared the isotopic ratios of carbon and nitrogen between Q-flies reared on different larval diets and wild flies collected from diverse locations in Australia and New Caledonia. Finally, we conducted a release-recapture study to corroborate differences in stable isotope C and N ratios in laboratory-reared and wild Q-flies. The delta N-15 values obtained from wild and laboratory Q-flies showed high variability that is likely related to the food source of the larval and/or adult stage and do not offer an effective means to discriminate between sterile and wild Q-flies. The delta C-13 values of examined wild Q-flies ranged from - 27.46 to - 24.37 parts per thousand VPDB, whereas those from laboratory-reared, released and recaptured Q-flies ranged from - 25.73 to - 19.26 parts per thousand VPDB. Differences in delta C-13 values resulted in 100% correct classification of wild flies and 96.88% correct classification of released flies. Measurements of intrinsic delta C-13 values offer a precise tool to discriminate between sterile and wild Q-flies in SIT programs, regardless of the composition of the larval or adult pre-release diets.
Living in the endosymbiotic world of Wolbachia: A centennial review
17794R. Kaur, J. D. Shropshire, K. L. Cross, B. Leigh, A. J. Mansueto, V. Stewart, S. R. Bordenstein and S. R. Bordenstein, Cell Host and Microbe, 29:879-893. 2021-05-03 20:31:30.
The most widespread intracellular bacteria in the animal kingdom are maternally inherited endosymbionts of the genus Wolbachia. Their prevalence in arthropods and nematodes worldwide and stunning arsenal of parasitic and mutualistic adaptations make these bacteria a biological archetype for basic studies of symbiosis and applied outcomes for curbing human and agricultural diseases. Here, we conduct a summative, centennial analysis of living in the Wolbachia world. We synthesize literature on Wolbachia's host range, phylogenetic diversity, genomics, cell biology, and applications to filarial, arboviral, and agricultural diseases. We also review the mobilome of Wolbachia including phage WO and its essentiality to hallmark reproductive phenotypes in arthropods. Finally, the Wolbachia system is an exemplar for discovery-based science education using biodiversity, biotechnology, and bioinformatics lessons. As we approach a century of Wolbachia research, the interdisciplinary science of this symbiosis stands as a model for consolidating and teaching the integrative rules of endosymbiotic life.
Genetically modified mosquitos: Biohacking for disease prevention.
16941D. Maloney, HACKADAY, 2021-05-03 15:02:07.
Mosquito control is basically a numbers game, stacked in their favor. Since each female lays 100 to 200 eggs in a clutch, in wet climates, mosquitos are simply too prolific to get ahead of using standard means. Coupled with collateral damage to the environment — draining wetlands carries potentially huge impacts on a wide range of species, as does the indiscriminate use of pesticides — the search for new control methods with less harmful ecological side-effects has led to research into genetic methods of reducing mosquito populations. The idea of genetically engineering insects is nothing new. The fruit fly Drosophila melanogaster has had its genome extensively modified for over 100 years, first using standard mating and crossing techniques and later using transgenic methods to insert, delete, and edit genes. The result has been a wealth of knowledge about how the genetics of higher organisms work, as well as models for human diseases ranging from diabetes to Parkinson’s. But in general, transgenic fruit flies are simply model organisms destined to live and die in the lab. The concept of building a genetically modified insect for release into the wild is fairly new. Oxitec, the company behind the planned releases of transgenic mosquitos in Florida, has been working on the genetic control of a range of pest insect species since it was founded in 2002. They are currently on their second generation of genetically modified Aedes aegypti mosquitos, which is the insect that will soon be tested in Florida. The mosquito, dubbed OX5034, has been genetically engineered to be self-limiting. Both male and female OX5034 mosquitos carry a synthetic gene that is lethal only to females. The plan is to release OX5034 male mosquitos into a wild population where they’ll breed with unmodified females. These females will take a blood meal and lay eggs that carry the synthetic gene. Only the male eggs in the clutch will develop into adulthood; the females will all die during the larval and pupal stage, which will eventually reduce the number of blood meals taken and the potential for disease spread.
First genetically modified mosquitoes released in the United States
16939E. Waltz, Nature, 2021-05-03 14:56:33.
After a decade of fighting for regulatory approval and public acceptance, a biotechnology firm has released genetically engineered mosquitoes into the open air in the United States for the first time. The experiment, launched this week in the Florida Keys — over the objections of some local critics — tests a method for suppressing populations of wild Aedes aegypti mosquitoes, which can carry diseases such as Zika, dengue, chikungunya and yellow fever. Oxitec, the firm based in Abingdon, UK, that developed the mosquitoes, has previously field-tested the insects in Brazil, Panama, the Cayman Islands and Malaysia. But until now, owing to a circuitous series of regulatory decisions and pushback from Florida residents (see ‘A long road’), no genetically engineered mosquito had been trialled in the United States — even though the country previously allowed tests of a genetically engineered diamondback moth (Plutella xylostella) in New York and an engineered pink bollworm (Pectinophora gossypiella) in Arizona, both developed by Oxitec. “When something new and revolutionary comes along, the immediate reaction of a lot of people is to say: ‘Wait.’,” says Anthony James, a molecular biologist focused on bioengineered mosquitoes at the University of California, Irvine. “So the fact that [Oxitec] was able to get the trial on the ground in the United States is a big deal.”
Oxitec releases first genetically modified mosquitoes in U.S.
16928J. Knutson, Axios, 2021-05-01 15:46:09.
Oxitec, a British startup determined to prevent instances of mosquito-borne disease, released thousands of genetically modified mosquito eggs in the Florida Keys this week as part of a test approved by the Environmental Protection Agency and Florida's agriculture department. Why it matters: It marks the first release of genetically modified mosquitoes in the U.S. and has some locals worried about how this will impact the broader ecosystem, according to CNN. How it works: Oxitec expects to target Aedes aegypti, an invasive species of mosquito that carries several dangerous diseases like yellow fever, dengue and Zika virus.
Armyworm meets Friendly moth
17066M. Francisco, Nature Biotechnology, 39:532-532. 2021-05-01 14:11:25.
The fall armyworm moth, a pest so named for its caterpillar’s invasive and destructive behavior, may now have to contend with a ‘Friendly’ foe. UK-based Oxitec and agbiotech giant Bayer have jointly developed a genetically modified variety to combat the fall armyworm (Spodoptera frugiperda), an insect pest causing severe destruction to corn, rice and sorghum crops in more than 100 countries. Brazil has approved field trials of the GM ‘Friendly’ fall armyworm moths. The technology, originally developed at Oxford University, uses male self-limiting fall armyworm moths. When males are released into infested areas, the moths mate with wild females, but as they produce no female offspring in the next generation, this reduces the population of crop-eating caterpillars. The approach is species specific, is self-limiting in the environment, and has no impact on beneficial insects such as bees. Oxitec has successfully used the technology with mosquitoes to control dengue and Zika in Brazil, and is currently releasing Friendly mosquitoes in the Florida Keys as part of a US Environmental Protection Agency trial. Though some groups remain opposed to the technology, most experts agree that GMOs must be part of an integrated pest management solution, in addition to rotating crops, encouraging the growth of a pest’s natural predators, and using pesticides selectively to mitigate resistance buildup.
Genetically modified mosquitoes have landed in the Keys. Here’s what you need to know
16918G. Filosa, Miami Herald, 2021-05-01 13:54:49.
More than 20 million genetically modified mosquitoes are coming to the Florida Keys this year, in a landmark project by British biotech company Oxitec and Monroe County’s Mosquito Control District. This mosquito control method hasn’t been used in the U.S. before. It’s a pilot program and the first trial began over the past week. The project is aimed at reducing the population of the invasive Aedes aegypti, which carries diseases like Zika. This is the first time in the country that the U.S. Environmental Protection Agency has issued the “experimental use permit” for this method.
What Are GMO Mosquitoes and What Is Their Purpose?
17038A. Krosofsky, GREENMATTERS, 2021-05-01 11:29:18.
Scientists have made GMO corn, strawberries, even many types of farm animals. Now, it seems, they have managed to genetically modify mosquitoes as well. But what is the purpose of GMO mosquitoes, and why would scientists go out of their way to create something that is already a problem for a huge portion of the planet’s population? As it turns out, GMO mosquitoes are a way to fight fire with fire. By creating and releasing their own genetically modified mosquitoes into existing populations, a few clever scientists have managed to curb the spread of dangerous mosquito-borne diseases like the Zika virus. According to the CDC, GMO mosquitoes are modified from the Aedes aegypti mosquito species. Aedes aegypti mosquitoes are commonly found in many parts of the U.S., including Florida and Texas. They are well known for spreading and carrying viruses like Zika, dengue, and chikungunya, but the GMO versions of these insects are designed to stop the spread of those diseases right at the source: the carriers themselves.
Genetically modified mosquitoes | Connect the Dots
16905thv11, THV11, 2021-04-30 17:56:23.
This is a local TV story from Arkansas of the Oxitec trial being conducted in Florida.
‘Home to GMO Mosquitoes?!’ Florida Unleashes a Billion Lab Grown Mosquitoes
16925Anonymous, B and T MAGAZINE, 2021-04-30 15:40:06.
Up to a billion genetically engineered mosquitoes are going to be released in the Florida Keys—but locals are having none of it, with billboards erected saying ‘no!’ to the damned blood suckers. The genetically-modified mosquitoes, known as the OX5034, were made in a laboratory in London by British biotech firm Oxitec, in a bid to kill-off a species in the Florida Keys that carries dengue fever, Zika virus, and yellow fever. It comes after more than 7,300 dengue cases were reported in the US in the past decade, Vice reports. While most were contracted outside America, 71 were transmitted in Florida, according to the CDC.
The Release of 1 Billion Exterminator Mosquitoes Has Begun
16922D. Noor, Gizmodo, 2021-04-30 15:32:45.
Tens of thousands of male mosquitoes are descending on the Florida Keys. But these are no ordinary mosquitoes: They’re genetically modified, and they were planted around the state on purpose. It’s part of a plan to curb disease by releasing 1 billion mosquitoes across two states—but it’s giving some folks the heeby jeebies. Workers placed boxes of mosquitoes’ eggs—two on Cudjoe Key, one on Ramrod Key and three on Vaca Key—on Thursday, and expect them to hatch in about a week. They’ll repeat the process over the coming months, releasing 12,000 of the bugs per week for 12 weeks. That’s 144,000 mosquitoes overall—gross. The project marks the first time GMO mosquitoes have ever been released in the U.S., was launched by the Florida Keys Mosquito Control District (FKMCD) with the private British firm biotech Oxitec. It’s an attempt to curb the spread of dengue, Zika and yellow fever.
First-ever US release of genetically modified mosquitoes begins in Florida Keys
16920S. LaMotte, CNN, 2021-04-30 15:27:44.
The first release of genetically modified mosquitoes in the United States began this week in the Florida Keys -- the culmination of a decade-long effort by local mosquito control authorities to see if a genetically modified organism is a viable alternative to spraying insecticides in the region.For the first 12-week phase, blue-and-white boxes containing about 12,000 GMO eggs developed by a US-owned, British-based company called Oxitec have been placed in six small areas of Ramrod Key, Cudjoe Key and Vaca Key. When water is added, the mosquitoes hatch, mature and enter the environment over the next week or so. A small, vocal group of Florida Key residents have fought the release of what they call "mutant mosquitoes" since the project was announced -- and they are incensed. "Our opposition has been long and strong," said Barry Wray, the executive director of the Florida Keys Environmental Coalition. "We live here, this our home, and they're forcing this down people's throats." "The only thing you can do legally at this point is stand in your yard with an insect fogger," said Mara Daly, a resident of Key Largo, Florida, who has fought the release for eight years. "You can't touch a box, but you can fog the s**t out of your own yard if you don't want to be a part of the trial."
The first genetically modified mosquitoes released in the U.S. to buzz in the Florida Keys
16897K. Weintraub, USA Today, 2021-04-29 17:37:24.
On Thursday morning, workers from a British company placed basketball-sized cardboard boxes into six yards in the Florida Keys. Then they added water. In a week or so, 12,000 male Aedes aegypti mosquitoes will – one by one – begin buzzing out of each box, the first genetically modified mosquitoes to be released in the United States. Local officials argue the trial is necessary at a time when pesticides are increasingly ineffective against these dangerous pests. A 2016 vote on the project claimed a solid majority of support in most of the surrounding counties. "At the end of the day, our hope is to be able to control this mosquito more efficiently and keep our population below any sort of disease transmission threshold," said Andrea Leal, executive director of the Florida Keys Mosquito District. "Our toolbox for Aedes aegypti control is shrinking, unfortunately, and that's making us think outside of the box."
A Billion Lab-Grown Mosquitos Are Being Released and People Are Freaking Out
16895V. Kipnis, Vice, 2021-04-29 17:08:03.
On Thursday afternoon, six Florida Keys residents will walk out into their yards and set out aquamarine cardboard boxes filled with mosquito larvae. Then, water will be poured into the containers. For the next ten days, as the mosquitoes grow into adults, their neighbors will be waiting to see what happens next. That’s because these aren’t just any mosquitoes: These are genetically-modified organisms, known as the OX5034, and they were made in a laboratory in London. Under a two-year Experimental Use Permit approved by the EPA, the British biotech firm Oxitec has been green-lit to release over 1 billion genetically modified mosquitoes across 6,600 acres in Florida and Texas. For their pilot project, they’re focusing on the lower Florida Keys, where in the coming 12 weeks, they plan to release 144,000 non-biting male mosquitoes from six different locations—making this the first time ever that a genetically-engineered mosquito will be let out into an open ecosystem in the United States.
The mosquito-bite fight begins
16883F. Billingsley, Click2Houston, 2021-04-29 15:10:43.
Anyone who thought February’s freeze would kill all the mosquitos is biting up the wrong leg. They are back and, seemingly so, with a vengeance (did surviving just make them stronger, one wonders?). In Florida this week, an interesting and controversial fight against the bite begins after more than a decade of getting there. The company Oxitec will be releasing 144,000 Genetically Modified Mosquitoes in the Florida Keys designed to fight the mosquito population. Did you ever take the antibiotic tetracycline? I took it to fight acne as a kid but it treats lots of other bacterial infections. Oxitec has engineered all their mosquitoes with a gene that makes only the females depend on tetracycline. Without it, the females die and it’s the females that bite. So all the eggs from the engineered mosquitoes will be shipped to Florida and when they hatch, the engineered female mosquitoes won’t have any tetracycline and they are toast.
Modeling and analysis of the implementation of the Wolbachia incompatible and sterile insect technique for mosquito population suppression.
17098B. Zheng, J. S. Yu and J. Li, Siam Journal on Applied Mathematics, 81:718-740. 2021-04-29 13:06:06.
Mathematical analysis may offer guidance in designing effective mass release strategies for the area-wide application of this Wolbachia incompatible and sterile insect technique in the future. The two most crucial concerns in designing release strategies are how often and in what amount should Wolbachia-infected mosquitoes be released in order to guarantee population suppression. Motivated by the experimental data from the Guangzhou mosquito factory and the release strategy implemented on two islands, we formulate and analyze a mosquito population suppression model considering the situation for the release period T less than the sexual lifespan of Wolbachia-infected males. We define release amount thresholds g(1)* and g(2)* with g(1)* < g(2)*. When the release amount c satisfies c >= g(2)*, population suppression is always achievable, as is mathematically manifested by the global asymptotic stability of the origin. However, when c is an element of (0, g(1)*], we find that suppression can be achieved only if the initial wild mosquito population is small enough. This is mathematically proved by the local asymptotic stability of the origin, together with the existence of exactly two T-periodic solutions, one of which is asymptotically stable and the other of which is unstable, with T being the waiting period between two consecutive releases. For c is an element of (g(1)*, g(2)*), we find sufficient conditions on the nonexistence of T-periodic solution, and the existence of at most two T-periodic solutions.
Nearly 144K GMO Mosquitoes to be Released in South Florida: What We Know
16902J. Prigeon, 6 South Florida, 2021-04-28 17:46:54.
Nearly 144,000 genetically modified mosquitoes will be released in South Florida this week as part of an effort to reduce the population disease-carrying mosquitoes. The landmark release of GMO insects marks the beginning of the U.S.-approved program to control the number of Aedes aegypti mosquitoes in the area. The project will place boxes loaded with Oxitec’s non-biting male mosquitoes in six areas around the Florida Keys to mate with biting female mosquitoes. As a result of the encounters, the female offspring will not survive and – hopefully – will reduce the dangerous mosquito's population in the area.
Nation’s first trial of genetically modified mosquitoes starts in Florida Keys
16889S. Brock, TODAY, 2021-04-28 15:15:04.
To control the population of potentially disease-spreading mosquitoes, a controversial project is getting underway in the Florida Keys, highlighted by the release of even more mosquitoes that have been genetically modified. NBC’s Sam Brock reports for TODAY from Miami.
Florida Unleashing Thousands of Mosquitoes
16886Anonymous, The Weather Channel, 2021-04-28 15:11:10.
Florida will begin releasing thousands of genetically modified mosquitoes in the Keys this week to combat diseases like Zika and dengue. But the government’s green light has some residents seeing red.
GMO mosquitoes to be released in Florida Keys
16880NBC News, WRCBtv, 2021-04-28 15:02:40.
Florida will begin releasing genetically modified mosquitoes this week as part of its efforts to control one of the disease-spreading species of the biting insect. The state will release almost 144,000 nonbiting male mosquitoes in the coming weeks engineered by the British firm Oxitec that are meant to mate with biting females, with any resulting female offspring unable to survive. The project was approved after years of public comment and official review. "As we are seeing development of resistance to some of our current control methods, we are in need of new tools to combat this mosquito," Andrea Leal, executive director of the Florida Keys Mosquito Control District said in a press release. The project is meant to control the population of the Aedes aegypti mosquito, which can spread dengue fever, Zika virus and yellow fever, as well as heartworm to pets and animals.
Nearly 150,000 Gene-Hacked Mosquitoes to Be Unleashed in Florida
16878S. Kim, Newsweek, 2021-04-28 14:58:55.
Nearly 150,000 mosquitoes that have been genetically modified by Oxitec, a biotechnology company based in the U.K., will be released across parts of Monroe County's Florida Keys region starting this week. The release is part of an experiment to help combat a disease-transmitting local mosquito population (the Aedes aegypti mosquito species) that is responsible for "virtually all mosquito-borne diseases transmitted to humans" such as dengue, Zika and yellow fever, the company says. Speaking to Newsweek, a spokesperson for Oxitec said: "We are releasing 12,000 [mosquitoes] per week for 12 weeks," which equates to a total of 144,000 mosquitoes, the spokesperson added. The experiment—a collaboration between the Florida Keys Mosquito Control District (FKMCD) and Oxitec—received approval from the U.S. Environmental Protection Agency (EPA) and the Florida Department of Agriculture and Consumer Services (FDACS). It is also supported by the U.S. Centers for Disease Control and Prevention as well as an independent advisory board, Oxitec says.
Genetically modified mosquito larvae to be released in Florida Keys
16869E. Helmore, The Guardian, 2021-04-28 14:13:40.
The Florida Keys will this week see the release of genetically modified, non-biting male mosquito larvae as part of a controversial program designed to curb the spread of insect-borne diseases such as dengue, Zika and yellow fever. The Florida Keys Mosquito Control District and British firm biotech Oxitec announced last week that 12,000 of the invasive Aedes aegypti mosquito species are expected to emerge each week for twelve weeks from six locations: two on Cudjoe Key, one on Ramrod Key and three on Vaca Key. US researchers seek citizen scientists as billions of Brood X cicadas set to emerge Eventually it is planned that hundreds of millions of the mosquitoes might be released. Oxitec’s non-biting male mosquitoes will mate with the local biting female mosquitoes and since the female offspring cannot themselves survive to reproduce, the population of Aedes aegypti is subsequently controlled. According to the CDC, the genetically modified mosquitoes carry two types of genes: a fluorescent marker gene that glows under a special red light, and a self-limiting gene that prevents female mosquito offspring from surviving to adulthood.
Florida set to release swarms of GMO mosquitoes as residents decry ‘criminal experiment’ by Bill Gates-backed biotech
16866rt com, rt com, 2021-04-28 14:04:30.
A plan to release thousands of genetically modified mosquitoes in an effort to combat disease in the Florida Keys has triggered dire concerns among locals, some saying the “criminal” experiment will turn them into guinea pigs. Spearheaded by the Florida Keys Mosquito Control District (FKMCD) and Oxitec, a British biotech firm that’s received backing from the Bill and Melinda Gates Foundation, the project aims to turn the first swarms of gene-edited bugs loose into the Keys starting sometime this week, the two bodies announced in a joint statement. For the first leg of the plan, set to be expanded later, mosquito boxes will be placed at six locations, which over 12 weeks will release around 144,000 Aedes aegypti mosquitoes, a species most closely linked with transmitting illnesses such as dengue, Zika and yellow fever. If all goes according to plan, the male, non-biting bugs will mate with local biting females, whose female offspring are programmed to die off, helping to control the Aedes aegypti population and reduce the spread of disease. While the particular species makes up only about 4% of the overall population in the Keys, it is behind “virtually all” mosquito-borne diseases passed to humans, as well as some that are transmitted to animals, such as heartworm, according to Oxitec.
“Maskandi experience”: exploring the use of a cultural song for community engagement in preparation for a pilot Sterile Insect Technique release programme for malaria vector control in KwaZulu-Natal Province, South Africa 2019
17029P. N. Manana, S. Jewett, J. Zikhali, D. Dlamini, N. Mabaso, Z. Mlambo, R. Ngobese and G. Munhenga, Malaria Journal, 20:11. 2021-04-28 11:06:19.
Background An assessment of the Sterile Insect Technique (SIT) as a complementary malaria vector control tool, is at an advanced stage in South Africa. The technique involves the release of laboratory-reared sterilized male mosquitoes of the major malaria vector Anopheles arabiensis, raising social, ethical and regulatory concerns. Therefore, its implementation largely depends on community participation and acceptance. Against this background, it is critical that robust and effective community strategies are developed. This study describes the development of a cultural song to engage the community and increase awareness on SIT and malaria control in KwaZulu-Natal, South Africa. Methods An exploratory concurrent mixed-methods study was conducted to get opinions about the effectiveness of a cultural song developed to engage communities and increase acceptability of the SIT technology. Two self-administered surveys (expert and community) were conducted. Additionally, more in depth opinions of the song and its effectiveness in conveying the intended information were investigated through three community dialogue sessions with community members in the study area. Results A total of 40 experts and 54 community members participated in the survey. Four themes were identified in relation to the appropriateness and effectiveness of the song, with a fifth theme focused on recommendations for adaptations. Overall, the song was well received with the audience finding it entertaining and informative. Responses to unstructured questions posed after the song showed an increase in the knowledge on malaria transmission and SIT technology. In particular, the explanation that male mosquitoes do not bite allayed anxiety and fears about the SIT technology. Conclusion The song was deemed both culturally appropriate and informative in engaging community members about the SIT technology. It proved useful in promoting health messages and conveying SIT technology as a complementary malaria vector control tool. With minor adaptations, the song has potential as an area-wide community engagement tool in areas targeted for sterile male releases.
BUZZ OFF Florida residents blast pest control ‘TERRORISTS’ over plans to unleash a BILLION mutant mosquitoes in the Keys
16857J. Bentley-York, The SUN, 2021-04-27 20:46:15.
The areas Mosquito Control District (FKMCD) are set to release the gene hacked ‘fraken-squitoes' in a bid to fight insect-borne viruses like yellow fever. A BILLION mutant mosquitoes are set to be released in the Keys to fight insect-borne viruses like yellow fever Florida pest control chiefs have been branded “terrorists” over the plans. The trial is set to begin this week, seeing a first phase of up to 144,000 modified mosquitoes released over the next 12 weeks. The project aims to reduce the numbers of Aedes aegypti species which are known for carrying diseases including dengue, chikungunya, zika and yellow fever. The male mosquitoes, developed by British biotech company Oxitect, do not bite, and will be introduced in small areas in a select number of neighborhoods in the Monroe area. However, Florida residents are calling on the US Environmental Protection Agency (EPA) to end "this live experiment" as they blasted the organisation as “terrorists.” Barry Wray of the Florida Keys Environmental Coalition said: “People here in Florida do not consent to the genetically engineered mosquitoes or to being human experiments.”
Florida to release a billion genetically modified mosquitoes and people are worried
16871B. Robinson, indy100, 2021-04-27 14:19:58.
It sounds like the pitch for a horror movie, but Florida’s about to release up to a billion genetically modified mosquitoes in the Keys. What could go wrong? Florida residents and environmentalists are already voicing their concerns after state officials and Oxitec, a biotechnology a UK-based biotechnology company, announced plans to release the critters over a two year period in Monroe County, in the Florida Keys section of the state. But why? In a press release from Friends of the Earth, they state that the project attempts to reduce the number of Aedes aegypti, one of the many species of mosquitoes that carry infectious diseases such as Yellow Fever and Zika.
Thousands of genetically modified mosquitoes being released in Florida
16863T. Lapin, New York Post, 2021-04-27 13:58:39.
Thousands of genetically modified mosquitoes have begun to be released in Florida this week as part of an effort to combat a disease-spreading species of the insect. The buzzy project, from British biotech company Oxitec, aims to curb the population of Aedes aegypti mosquitoes, which can spread diseases such as Zika and dengue fever, The Miami Herald reported. The project aims to have genetically modified male mosquitoes mate with non-modified females, which are the ones that bite. A so-called “death mechanism” would then act to prevent any resulting female offspring from surviving.
Halt This Nightmare’: Alarm as Florida Set to Begin Release of Genetically Engineered Mosquitoes
16861J. Johnson, Common Dreams, 2021-04-26 20:59:02.
Environmentalists and Florida residents voiced concern and outrage Monday as state government officials and the biotechnology giant Oxitec announced plans to move ahead this week with a pilot project that involves releasing up to a billion genetically engineered mosquitoes in Monroe County over a two-year period. Presented by local authorities as an effort to control the population of Aedes aegypti—a mosquito species that can carry both the dengue and yellow fever virus—critics warn that the effort's supposed benefits and its potential negative consequences have not been sufficiently studied. Responding to news that the first boxes of genetically modified mosquitos are set to be placed in six locations in Monroe County this week, Friends of the Earth noted in a press release that "scientists have raised concerns that GE mosquitoes could create hybrid wild mosquitoes which could worsen the spread of mosquito-borne diseases and could be more resistant to insecticides than the original wild mosquitoes."
Florida residents claim ‘pest control trial’ that will release up to a BILLION genetically engineered mosquitos in the Keys to reduce species carrying diseases is ‘TERRORISM’
16859S. Liberatore, Daily Mail, 2021-04-26 20:54:47.
The Florida Keys will soon be buzzing with close to a billion 'fraken-squitoes' – gene-hacked mosquitoes aimed at eradicating a disease carrying mosquito. The Florida Keys Mosquito Control District (FKMCD) and Oxitec, a British biotech company, are starting the first-ever U.S. release of genetically engineered (GE) Aedes aegypti mosquitoes this week, which will see up to a billion over a two-year period. The project aims to reduce the numbers of Aedes aegypti, one of several mosquito species that can carry diseases including dengue, chikungunya, Zika and yellow fever. Floridians, however, are calling on the US Environmental Protection Agency (EPA) to end 'this live experiment' saying they are being subjected to terrorism by the FKMCD.
Coalition Against GMO Mosquito Condemns Release of Genetically Engineered Mosquitoes
16853GMO Free USA, 3BL CSRwire, 2021-04-26 20:40:26.
Despite a decade of community opposition, the experimental release of genetically engineered mosquitoes begins today in the Florida Keys. British biotech corporation, Oxitec, in collaboration with the Florida Keys Mosquito Control District, plans to release up to a billion genetically engineered mosquitoes in two phases. GMO Free USA and the Coalition Against GMO Mosquitoes condemn the uncontrolled release and are airing radio spots to educate Florida Keys residents about the health and environmental risks. This unprecedented mass release of a genetically engineered insect is the first of its kind in the United States and many Florida Keys residents remain unaware. The Coalition Against GMO Mosquitoes recently launched an educational website, StopGMM.com, and sponsored a local billboard to increase public awareness and galvanize opposition. The new radio spot will run daily on multiple stations. Oxitec and the FKMCD have failed to provide sufficient answers to the most pressing questions posed by concerned residents. Some residents have reached out to government officials at the EPA, in Congress and the White House to request intervention to halt the experiment until thorough research is conducted.
Nation’s First Trial Of Genetically Modified Mosquitoes Starts In Florida Keys
16851N. Klingener, WLRN, 2021-04-26 20:35:50.
Boxes containing the eggs of genetically modified Aedes aegypti mosquitoes, water and a little food are being placed in six locations in the Lower and Middle Keys this week — in a trial that will be the first of its kind in the United States. The genetic modification is intended so that female offspring won't survive. Female mosquitoes are the ones that bite and can transmit diseases like dengue and zika. The genetically modified males are supposed to breed with wild females — and then their female offspring won't survive, either. Andrea Leal is in charge of the Florida Keys Mosquito Control District. The district has been working with the British firm Oxitec for more than a decade, since a 2009-10 outbreak of dengue fever in Key West.
Genetically-engineered mosquitoes set for release in Florida Keys: Science offers tool to fight Zika, dengue, malaria but critics claim it’s unnecessary and potentially dangerous
16808J. Musto, Genetic Literacy Project, 2021-04-22 16:02:53.
U.K.-based biotechnology company Oxitec has partnered with the Florida Keys Mosquito Control District in an effort to control the invasive and disease-spreading female Aedes aegypti mosquitoes in the region. Oxitec’s [genetically modified] male mosquitoes — which don’t bite, unlike the recently-discovered yellow fever-carrying Aedes scapularis mosquitoes — will be introduced in small areas in a select number of neighborhoods between mile markers 10 and 93 in the Keys. In recent reporting from Undark, the non-profit digital science magazine notes that Oxitec had been proposing an experimental release in the Keys for years and that it had been rejected before in both Key Haven and Key West — though some residents in surrounding areas voted in support of the release.
Development of Sterile Insect Technique for Control of the European Grapevine Moth, Lobesia botrana, in Urban Areas of Chile
16849G. S. Simmons, M. C. Salazar Sepulveda, E. A. Fuentes Barrios, M. Idalsoaga Villegas, R. E. Medina Jimenez, A. R. Garrido Jerez, R. Henderson and H. Donoso Riffo, Insects, 12. 2021-04-22 13:20:22.
The European grapevine moth, a Palearctic pest, was first detected in the Americas in 2008. Its establishment in Chile presented production and export issues for grapes and other fruits, and a national control campaign was launched. Urban areas next to agricultural production areas were recognized as a challenge for effective control. In 2015, a SIT laboratory was established in Arica, Chile to evaluate its potential for urban control. Progress included the development and evaluation of artificial diets, a mass-rearing of 75,000 moths/week, confirmation of 150 Gy as an operational dose for inherited sterility, and releases of sterile moths in a 25 ha urban area next to fruit production areas. Season-long releases demonstrated that high overflooding ratios were achieved early in the season but decreased with a large increase in the wild moth population. Sterile moth quality was consistently high, and moths were observed living in the field up to 10 days and dispersing up to 800 m. Recommendations for further development of the SIT include conducting cage and field studies to evaluate overflooding ratios and mating competitiveness, measuring of infestation densities in release and no-release areas, and conducting trials to evaluate combining SIT with compatible integrated pest management (IPM) tactics such as fruit stripping and use of mating disruption.
UK biotech firm’s 750 mn GM mosquitoes will mate with females off Florida, sow a deadly gene
16819S. Ramesh, The Print, 2021-04-20 16:27:48.
Oxitec, a UK-based biotechnology company, plans to release genetically modified mosquitoes in the Florida Keys islands off the US this month as part of a trial to curb mosquito-borne diseases like dengue and the one caused by the Zika virus. This is the latest genetic engineering experiment targeting mosquitoes that is aimed at tackling diseases that continue to kill thousands every year — an approach that has critics as well as backers. Only females of mosquitoes bite, while males feed on all nectar. The mosquitoes Oxitec plans to release will all be male, carrying a protein that will kill all their female offspring. The exact locations where the mosquitoes will be released have not been made public. The objective over time is to reduce the population of the Aedes aegypti mosquito, which spreads both the above-mentioned diseases as well as chikungunya and yellow fever. Mosquito populations in Florida are believed to have grown resistant to a common group of insecticides, prompting worries.
Estimates of the population size and dispersal range of Anopheles arabiensis in Northern KwaZulu-Natal, South Africa: implications for a planned pilot programme to release sterile male mosquitoes
17062M. L. Kaiser, O. R. Wood, D. Damiens, B. D. Brooke, L. L. Koekemoer and G. Munhenga, Parasites and Vectors, 14:18. 2021-04-19 13:57:18.
The Anopheles gambiae complex and An. funestus group species made up the majority of wild collections along with other anophelines. The An. arabiensis population size was estimated to be between 550 and 9500 males per hectare depending on time of year, weather conditions and method used. Average dispersal distance of marked males ranged from 58 to 86 m. Marked males were found in swarms with wild males, indicating that laboratory-reared males are able to locate and participate in mating swarms. Conclusions It was logistically feasible to conduct mark-release-recapture studies at the current scale. The population size estimates obtained may provide a guideline for the initial number of males to use for a pending SIT pilot trial. It is promising for future SIT trials that laboratory-reared marked males participated in natural swarms, appearing at the right place at the right time.
Florida to release genetically modified mosquitoes to fight disease
16812K. Jones, WND, 2021-04-17 16:07:26.
A biotechnology company will soon release genetically modified mosquitoes in certain areas of the Florida Keys in order to combat infectious diseases spread by the parasitic insects.The findings could lead to a new method for combating the spread of diseases such as the Zika virus and dengue fever, according to experts. Both diseases are commonly attributed to mosquito bites in humans.Fox News reported that a strain of mosquitoes developed by a United Kingdom-based company called Oxitec -- partnered with the Keys' Mosquito Control District -- will soon be released into a select number of neighborhoods in Florida. The aim of the experimental program is to control the population of the female Aedes aegypti mosquitoes which make life insufferable for many residents of the Keys.
Dengue fever and Zika The first genetically modified mosquitoes are released in Florida to fight disease
16805M. Woolridge, The Daily Guardian, 2021-04-17 15:46:01.
Biotechnology Corporation Oxitec Planning to release transgenic mosquitoes in Florida Keys. The company says its technology aims to combat dengue fever, a deadly disease transmitted by mosquitoes Aedes aegyptiIn addition to other diseases such as Zika.According to Who is the And the Centers for Disease Control and Prevention in the United States. However, some neighbors are against releasing this transgenic mosquito because they fear that they will become so Guinea pigs. Oxitec Attempts to release genetically modified mosquitoes from 2011But it was always getting delayed due to discussions of places and some scholars. Despite this, the Florida Keys Mosquito Control District agreed to Exam, Which will take place at various locations at Keys.
Scientists are now playing god with mosquitoes
16794M. Wehner, BGR, 2021-04-15 13:13:24.
Preventing illnesses in humans is a high priority for scientists that devote their lives to finding cures and techniques that keep people healthy, but sometimes a plan comes along that is so wild it can cause even the most devoted science fans to furrow their brow. In Florida, dengue fever regularly sickens over 100 people per year, and many of those individuals that contracted the virus are believed to have received it locally via mosquitos. Now, in what can only be described as the real-life equivalent of a made-for-TV sci-fi movie, scientists in Florida are prepared to unleash a swarm of genetically modified mosquitoes that will hopefully cut down on the number of the biting insects and, as a result, lower the numbers of mosquito-borne illnesses. The company behind the “OX5034” modified mosquitos is called Oxitec, and while it’s gained approval from the Environmental Protection Agency, there are still plenty of critics that fear unforeseen consequences.
First GMO mosquitoes to be released in the Florida Keys
16688T. White, UNDARK, 2021-04-12 15:18:49.
Oxitec says its technology will combat dengue fever, a potentially life-threatening disease, and other mosquito-borne viruses — such as Zika — mainly transmitted by the Aedes aegypti mosquito. While there have been more than 7,300 dengue cases reported in the United States between 2010 and 2020, a majority are contracted in Asia and the Caribbean, according to the U.S. Centers for Disease Control and Prevention. In Florida, however, there were 41 travel-related cases in 2020, compared with 71 cases that were transmitted locally. Native mosquitoes in Florida are increasingly resistant to the most common form of control — insecticide — and scientists say they need new and better techniques to control the insects and the diseases they carry. “There aren’t any other tools that we have. Mosquito nets don’t work. Vaccines are under development but need to be fully efficacious,” says Michael Bonsall, a mathematical biologist at the University of Oxford, who is not affiliated with Oxitec but has collaborated with the company in the past, and who worked with the World Health Organization to produce a GM mosquito-testing framework.
Introduction of a cold sensitivity-conferring mutation into the RTA-Bddsx hybrid system of Bactrocera dorsalis for establishment of a thermally controllable homozygous line
17327S. M. Dai, C. Y. Huang and C. Chang, Pest Management Science, 7. 2021-04-10 14:40:01.
BACKGROUND For efficient control of the economically important fruit pest Bactrocera dorsalis, a hybrid system combining ricin toxicity and sex-related alternative splicing of the doublesex gene has been developed. This system exhibits the expected female-specific lethal effect; however, the transgenic females do not survive, making it difficult to raise stable homozygous lines. Since modification of ricin toxin A chain (RTA) through a single-residue change (Gly(212) > Arg(212)) leads to cold-sensitive posttranslational repression of its toxicity, we utilized this unique property to obtain RTA-Bddsx females that survive at low temperature for line maintenance. RESULTS In transient expression experiments using embryonic injection, two groups treated with RTAcs-derived DNA (LERQcs and RTAcs) exhibited temperature-dependent effects. The toxicity was higher at 29 degrees C than at 18 degrees C. The proportion of males was close to 50% at 18 degrees C in all the tested groups except LERQcs-treated flies, which exhibited a high proportion of males (over 70%) at 29 degrees C. The results indicate the cold-sensitive responses of RTA and further suggest a female-specific lethal effect. Subsequently, 14 putative RTAcs-Bddsx transgenic Ds-Red(+) G(1) males were identified, and female-specific lethal effects were observed in Ds-Red(+) G(2) and G(3) lines under cultivation at 29 degrees C but not at 18 degrees C. The male ratio can be increased to up to 95% in G(3) line 001, indicating that RTAcs functions well in B. dorsalis. CONCLUSION The improved RTAcs-Bddsx system with conditional toxicity represents a novel and promising step toward the practical control of B. dorsalis.
Evidence for natural hybridization and novel Wolbachia strain superinfections in the Anopheles gambiae complex from Guinea
16990C. L. Jeffries, C. Cansado-Utrilla, A. H. Beavogui, C. Stica, E. K. Lama, M. Kristan, S. R. Irish and T. Walker, Royal Society Open Science, 8:18. 2021-04-07 14:55:09.
Wolbachia, a widespread bacterium which can influence mosquito-borne pathogen transmission, has recently been detected within Anopheles (An.) species that are malaria vectors in Sub-Saharan Africa. Although studies have reported Wolbachia strains in the An. gambiae complex, apparent low density and prevalence rates require confirmation. In this study, wild Anopheles mosquitoes collected from two regions of Guinea were investigated. In contrast with previous studies, RNA was extracted from adult females (n = 516) to increase the chances for the detection of actively expressed Wolbachia genes, determine Wolbachia prevalence rates and estimate relative strain densities. Molecular confirmation of mosquito species and Wolbachia multilocus sequence typing (MLST) were carried out to analyse phylogenetic relationships of mosquito hosts and newly discovered Wolbachia strains. Strains were detected in An. melas (prevalence rate of 11.6%-16/138) and hybrids between An. melas and An. gambiae sensu stricto (prevalence rate of 40.0%-6/15) from Senguelen in the Maferinyah region. Furthermore, a novel high-density strain, termed wAnsX, was found in an unclassified Anopheles species. The discovery of novel Wolbachia strains (particularly in members, and hybrids, of the An. gambiae complex) provides further candidate strains that could be used for future Wolbachia-based malaria biocontrol strategies.
Determining the Sterilization Doses under Hypoxia for the Novel Black Pupae Genetic Sexing Strain of Anastrepha fraterculus (Diptera, Tephritidae)
16672P. D. Giustina, T. Mastrangelo, S. Ahmad, G. Mascarin and C. Caceres, Insects, 12. 2021-03-30 13:38:24.
Our study reports for the first time the dose-sterility response under hypoxia for two different A. fraterculus strains. The pupae were derived from a bisexual strain (a Brazilian-1 population) and a recently developed genetic sexing strain (GSS-89). Two hours prior to irradiation, pupae were transferred to sealed glass bottles and irradiated when oxygen concentration was below 3%. Four types of crosses with nonirradiated flies of the bisexual strain were set to assess sterility for each radiation dose. For males from both strains, Weibull dose–response curves between radiation doses and the proportion of egg hatch, egg-to-pupa recovery, and recovery of adults were determined. The GSS males revealed high sterility/mortality levels compared to males from the bisexual strain at doses < 40 Gy, but a dose of 74 Gy reduced egg hatch by 99% regardless of the male strain and was considered the sterilizing dose. The fertility of irradiated females was severely affected even at low doses under hypoxia.
Village hears from experts as genetic-mosquito release experiment nears.
16678J. McCarthy, KEYSWEEKLY, 2021-03-26 14:56:47.
On March 18, Islamorada Village Council heard from several independent scientists who discussed information and issues behind the genetically modified mosquitoes for population and disease suppression. The scientists collectively said they’re neither for nor against the release. A representative from the Florida Keys Mosquito Control District and one from Oxitec responded following the presentation. Fred Gould, professor of North Carolina State’s Department of Entomology and Plant Pathology, briefly explained the strain of mosquitoes (OX5034) set for release. He said he was involved with another strain of genetically modified mosquitoes in development in 2010 when a field case study was conducted in Mexico. “In the laboratory, it turned out the male mosquitoes flew fine and mated well. But in the real environment, they weren’t as strong as the wild type mosquitoes and they basically had 3% of the matings. Instead of having half the matings, they had very few,” he said. Gould went on to say that this is also shown in work by Oxitec in Brazil, where it turns out that the genetic mosquitoes “are not very fit.” “It would take 30 of them, at least, to be equal to an individual wild type in terms of how many matings you have,” he said. “When you’re thinking about that, you have to recognize you have to release a lot of mosquitoes in order to have any activity. I just want to bring that home to you that it goes up and down as to what that percent fitness is, and we don’t know what that’ll look like in Florida. “Will it work? I want to say it might work just fine,” he continued. “There’s a chance that they’ll be doing these releases and it won’t be a simple thing.”
Evaluating unintended consequences of intentional species introductions and eradications for improved conservation management
16631D. E. Pearson, T. J. Clark and P. G. Hahn, Conserv Biol, 2021-03-19 14:52:01.
We conducted a global literature review of these conservation actions to quantify how often unintended outcomes occur and to elucidate their underlying causes. We found that studies reported intended outcomes in 51% of cases, a combination of intended outcomes and unintended outcomes in 26% of cases, and strictly unintended outcomes in 10% of cases. Hence, unintended outcomes were reported in 36% of all cases evaluated. In evaluating overall conservations outcomes (weighing intended vs unintended effects), some unintended effects are fairly innocuous relative to successful conservation objectives whereas others result in serious unintended consequences in recipient communities. Importantly, we also found that studies that assessed a greater number of community interactions with the target species were more likely to report unintended outcomes, suggesting that unintended consequences may be under-reported due to insufficient vetting.
Meiotic Cas9 expression mediates genotype conversion in the male and female mouse germline.
16618A. J. Weitzel, H. A. Grunwald, R. Levina, V. M. Gantz, S. M. Hedrick, E. Bier and K. L. Cooper, 2021.03.16.435716, 2021-03-17 17:52:21.
We previously showed that such a system of genotype conversion from heterozygous to homozygous after a sequence targeted CRISPR/Cas9 double strand DNA break is feasible in the female mouse germline. In the male germline, however, all double strand breaks were instead repaired by end joining mechanisms to form an 'insertion/deletion' (indel) mutation. These observations suggested that timing Cas9 expression to coincide with meiosis I is critical to favor conditions when homologous chromosomes are aligned and interchromosomal homology directed repair (HDR) mechanisms predominate. Here, using a Cas9 knock-in allele at the Spo11 locus, we show that meiotic expression of Cas9 does indeed mediate genotype conversion in the male as well as in the female germline. However, the low frequency of both HDR and indel mutation in both male and female germlines suggests that Cas9 may be expressed from the Spo11 locus at levels too low for efficient double strand DNA break formation. We suggest that more robust Cas9 expression initiated during early meiosis I may improve the efficiency of genotype conversion and further increase the rate of 'super-Mendelian' inheritance from both male and female mice.Competing Interest StatementVMG, SMH, EB, and KLC hold advisory board positions with Synbal, Inc. All other authors declare that they have no competing interests.
When More is Less: Mosquito Population Suppression Using Sterile, Incompatible and Genetically Modified Male Mosquitoes
18708S. L. Dobson, Journal of Medical Entomology, 58:1980-1986. 2021-03-11 13:50:08.
The current review of the Sterile Insect Technique (SIT) is motivated by new technologies and the recent renaissance of male release field trials, which is driving an evolution in mosquito control and regulation. Practitioners that are releasing male mosquitoes would do well to learn from past successes and failures, including political and public engagement complications. With examples that include nuanced integrations of the different technologies, e.g., combinations of Wolbachia and irradiation, it is critical that scientists understand and communicate accurately about the technologies, including their evolving management by different regulatory agencies in the USA. Some male release approaches are considered ‘pesticides’ and regulated by federal and state agencies, while other male release approaches are unregulated. It is important to consider how the new technologies fit with the more ‘traditional’ chemical applications of adulticides and larvicides. The economics of male release programs are substantially different from traditional control costs, which can be a challenge to their adoption by abatement districts. However, there is substantial need to overcome these complications and challenges, because the problem with invasive mosquitoes grows ever worse with factors that include insecticide resistance, globalization and climate change.
Mosquito anxiety prompts query from congressman
16592T. Java, Keynews.com, 2021-03-10 20:09:26.
Anxiety among some residents over the pending release of hundreds of millions of genetically modified mosquitoes next month in undisclosed locations throughout the Florida Keys has prompted Congressman Carlos Gimenez to seek answers from the U.S. Environmental Protection Agency. The Florida Keys Mosquito Control District and Oxitec, a British-based biotech company, plan to release genetically modified Aedes aegypti mosquitoes in selected neighborhoods between mile markers 10 and 93 as a way to control the wild population of the disease-carrying pest. This is the first experiment of its kind in the U.S.
New Pesticides Will Modify Insect Genes: What Could Go Wrong?
16587Food Tank, EcoWatch, 2021-03-09 19:44:05.
Farmers across the U.S. could soon fill their pesticide spray tanks with a substance known as interfering RNA (RNAi). (RNA is a molecule similar to DNA.) Insects that are exposed to it — either by eating crops sprayed with the substance or by landing on a crop and absorbing it through their bodies — would be genetically modified right there in the field. The pesticide would trigger a process inside the insects' cells to switch off or "silence" genes that are essential for survival — like those needed to make new, healthy cells — thus killing them.
Thirteenth meeting of the WHO Vector Control Advisory Group
17109Vector Control Advisory Group, WHO, 2021-03-08 18:23:57.
VCAG experts met virtually with product developers, innovators and researchers from 7 to 10 December 2020 for the 13th VCAG meeting. This report details the proceedings and outcomes of the meeting, including advice provided to the following applicants: bait stations; lethal house lures; reduced pathogen transmission induced by Wolbachia; spatial repellents; and treatment of humans and/or livestock with an endectocide
femaleless Controls Sex Determination and Dosage Compensation Pathways in Females of Anopheles Mosquitoes
16910E. Krzywinska, L. Ferretti, J. Li, J.-C. Li, C.-H. Chen and J. Krzywinski, Current Biology, 31:1084-1091.e4. 2021-03-08 18:07:47.
Here we show that in the African malaria mosquito Anopheles gambiae, a gene, which likely arose in the Anopheles lineage and which we call femaleless (fle), controls sex determination in females by regulating splicing of dsx and fruitless (fru; another terminal gene within a branch of the sex determination pathway). Moreover, fle represents a novel molecular link between the sex determination and dosage compensation pathways. It is necessary to suppress activation of dosage compensation in females, as demonstrated by the significant upregulation of the female X chromosome genes and a correlated female-specific lethality, but no negative effect on males, in response to fle knockdown. This unexpected property, combined with a high level of conservation in sequence and function in anopheline mosquitoes, makes fle an excellent target for genetic control of all major vectors of human malaria.
Sex Determination and Dosage Compensation: femaleless Is the Link in Anopheles Mosquitoes
16908M. Scott, Current Biology, 31:R260-R263. 2021-03-08 18:03:44.
A new study finds that the femaleless gene is essential for sexual development and repression of X-chromosome dosage compensation in the malaria vector Anopheles gambiae. This could provide the basis for a new genetic approach to control this pest.
Hybrid mosquitoes? Evidence from rural Tanzania on how local communities conceptualize and respond to modified mosquitoes as a tool for malaria control
16567M. F. Finda, F. O. Okumu, E. Minja, R. Njalambaha, W. Mponzi, B. B. Tarimo, P. Chaki, J. Lezaun, A. H. Kelly and N. Christofides, Malaria Journal, 20:134. 2021-03-06 14:11:52.
Different forms of mosquito modifications are being considered as potential high-impact and low-cost tools for future malaria control in Africa. Although still under evaluation, the eventual success of these technologies will require high-level public acceptance. Understanding prevailing community perceptions of mosquito modification is, therefore, crucial for effective design and implementation of these interventions. This study investigated community perceptions regarding genetically-modified mosquitoes (GMMs) and their potential for malaria control in Tanzanian villages where no research or campaign for such technologies has yet been undertaken.
Genetically modified mosquitoes for better health
16527D. Devis, COSMOS, 2021-03-04 18:24:41.
One method of preventing these mosquito-born diseases is to use insecticides to kill the mozzies and remove them, but sometimes this only works as a short term solution, or has unintended devasting effects on the ecosystem. Another method for decreasing the number of disease-carrying mozzies is to introduce disease resistant, genetically modified mozzies. These transgenic mozzies could be part of a gene drive system where they have a newly introduced disease-resistant gene, linked up with CRISPR mechanisms that help the gene dominate in the population by continuing to copy itself through the genome. All of this requires very thorough risk assessment.
Engineered expression of the invertebrate-specific scorpion toxin AaHIT reduces adult longevity and female fecundity in the diamondback moth Plutella xylostella
16653T. Harvey-Samuel, X. Xu, E. Lovett, T. Dafa'alla, A. Walker, V. C. Norman, R. Carter, J. Teal, L. Akilan, P. T. Leftwich, C. M. Reitmayer, H. A. Siddiqui and L. Alphey, Pest Management Science, 2021-03-04 17:21:00.
To increase the flexibility of future genetic pest management systems in the diamondback moth, we aimed to assess the use of a non-cell-autonomous, invertebrate-specific, neurotoxic effector ? the scorpion toxin AaHIT. This AaHIT effector was designed to be secreted by expressing cells, potentially leading to effects on distant cells, specifically neuromuscular junctions. We demonstrated the feasibility of using non-cell-autonomous effectors within a GPM context for the first time in Lepidoptera, one of the most economically damaging orders of insects. These findings provide a framework for extending this system to other pest Lepidoptera and to other secreted effectors.
Tensions rise as GM mosquito release nears in Florida Keys
16520T. O'Hara, Keynews.com, 2021-03-03 20:29:44.
Tensions seem to be rising as a planned release of genetically modified mosquitoes nears. The British-based biotech company Oxitec plans to release genetically modified Aedes aegypti mosquitoes in the Florida Keys sometime after April, but has yet to disclose exact locations in the Keys or a date.
Quantifying the risk of vector-borne disease transmission attributable to genetically modified vectors
16530G. R. Hosack, A. Ickowicz and K. R. Hayes, Royal Society Open Science, 8:201525. 2021-03-03 18:28:51.
The relative risk of disease transmission caused by the potential release of transgenic vectors, such as through sterile insect technique or gene drive systems, is assessed with comparison with wild-type vectors. The probabilistic risk framework is demonstrated with an assessment of the relative risk of lymphatic filariasis, malaria and o'nyong'nyong arbovirus transmission by mosquito vectors to human hosts given a released transgenic strain of Anopheles coluzzii carrying a dominant sterile male gene construct. Harm is quantified by a logarithmic loss function that depends on the causal risk ratio, which is a quotient of basic reproduction numbers derived from mathematical models of disease transmission. The basic reproduction numbers are predicted to depend on the number of generations in an insectary colony and the number of backcrosses between the transgenic and wild-type lineages. Analogous causal risk ratios for short-term exposure to a single cohort release are also derived. These causal risk ratios were parametrized by probabilistic elicitations, and updated with experimental data for adult vector mortality. For the wild-type, high numbers of insectary generations were predicted to reduce the number of infectious human cases compared with uncolonized wild-type. Transgenic strains were predicted to produce fewer infectious cases compared with the uncolonized wild-type.
Florida Keys moves forward with genetically modified mosquitoes
16524H. Vela, local10.com, 2021-03-03 18:08:13.
The feared GMO mosquitoes are not going away. Opponents of the technology fear the date of the release in the Florida Keys is getting closer, and they are not ready for the possible repercussions of the experiment. The fight over whether or not to release genetically modified mosquitoes in Monroe County has been going on for almost a decade. Barry Wray said the mosquito control team’s contractor wants to deliver the first batch in April. Wray, the executive director of the Florida Keys Environmental Coalition, said he doesn’t believe there is enough evidence to prove that the technology is safe. He said there is a need for independent scientific investigation. “You don’t really know what the long-term outcomes could be or how to quantify those risks, and if you can’t do that scientifically, then you don’t know how to responsibly mitigate it or detect if something is going awry,” Wray said.
Demographic and psychographic drivers of public acceptance of novel invasive pest control technologies
17086F. Eppink, P. J. Walsh and E. MacDonald, Ecology and Society, 26. 2021-03-01 15:15:26.
Invasive mammals are a primary threat to New Zealand's endemic species. In remote areas, aerial delivery of poison is the preferred method of pest management, although it faces some public backlash. Novel pest control technologies are currently being investigated as alternatives but may face similar concerns. To investigate potential social and demographic determinants of public perceptions of new methods for pest control, we conducted a national choice experiment, focused on several novel technologies: gene drives, Trojan females, and species-specific poisons. We found that preferences strongly depend on the type of technology, with Trojan female technology strictly preferred to the other two. Although several characteristics affected preferences in predictable ways education, trust in science, and liberal political leaning increased acceptance ;the same did not hold with preferences for aerial delivery. Our results are useful for targeting future engagement campaigns and leveraging existing efforts.
When and where will millions of mosquitoes be released? Here are details for Florida Keys
16485D. Goodhue, Miami Herald, 2021-02-25 21:09:17.
The Florida Keys Mosquito Control District announced this week a wide and vague planned range of deployment for the lab-designed mosquitoes — neighborhoods from mile marker 10 to 93. The trial is being conducted by British biotech company Oxitec. It’s a method approved by the U.S. Environmental Protection Agency, the state of Florida, and the mosquito control district’s five-member board, to try to eradicate or significantly reduce the local population of Aedes aegypti mosquitoes.
Sterile Insect Technique: Lessons From the Past
18706M. Q. Benedict, Journal of Medical Entomology, 58:1974-1979. 2021-02-25 13:35:08.
When E.F. Knipling conceived of the release of sexually sterile insects to suppress wild populations, he laid down several fundamental qualities that characterized suitable target species—some of which mosquitoes generally violate—including high reproductive rates and large population numbers. Regardless of this, their global importance in public health has led numerous research teams to attempt to use the mosquito sterile insect technique against several species. Because of the degree of financial commitment required for suppression programs, most releases have consisted of preliminary investigations of male performance, population characteristics, and production methods. Those that have accomplished suppression provide important insights regarding the challenges of production, dispersal, and immigration. Insights gained from these studies remain relevant today, regardless of the genetic control technology being applied. In this article, I highlight studies that were notable for the insights that were gained, the intrinsic difficulties that mosquitoes present, and synthesize these into recommendations for successful applications of the sterile insect technique and newer technologies to mosquitoes.
Company uses engineered mosquitoes to prevent diseases
16514N. Herzog and D. Niesel, The Daily News, 2021-02-24 21:47:32.
It’s amazing how many serious infectious diseases are transmitted by insects like ticks, fleas and mosquitoes. These are called vector-borne diseases, which are responsible for significant human suffering and economic disruption. Mosquitoes are responsible for the spread of many viral diseases including Zika, malaria, West Nile virus, Eastern Equine Encephalitis virus and many others. For the majority of these diseases, we don’t have effective therapeutics or vaccines to treat those that get sick. One approach to control these diseases is to eliminate or reduce the arthropod or insect vector populations using broad spectrum pesticides. These pesticides can cause health problems in humans, and the vectors can become resistant to these chemicals. A new strategy has emerged that involves genetically modifying mosquitoes to disrupt their ability to reproduce. This limits the mosquito population, reducing the possibility of disease spread.
Mosquito trial will begin in April, but Keys locations won’t be disclosed
16483S. Matthis, KEYSWEEKLY, 2021-02-23 20:54:42.
FKMCD spokesman Chad Huff wrote in an email, “The physical location of each box is still being finalized. Since most will be situated on private property at owner request, FKMCD-Oxitec will NOT be providing specific addresses due to privacy concerns and protection of project integrity.” Phil Goodman, chairman of the FKMCD said the decision to keep addresses confidential was an operations decision, not a decision by the elected board. “Right now, we don’t have any specific sites that are 100 percent selected,” said Andrea Leal, executive director of the FKMCD. “We are just narrowing down areas with potential.”
Locals protest over genetically modified mosquito plan in Florida Keys
16479D. Goodhue, Miami Herald, 2021-02-23 14:11:23.
Sometime this year, somewhere in the Florida Keys, a British biotech company is expected to release millions of genetically modified male mosquitoes in an effort to breed out of existence an invasive species of bug responsible for the transmittal of deadly diseases like dengue fever, chikungunya and Zika. But, the pilot project remains controversial, and a large segment of people who live in the island chain are trying to stop it. About two dozen people gathered Sunday morning outside the Murray Nelson Government and Cultural Arts Center in Key Largo to protest the planned release of the lab-designed bugs.
Population genomics of invasive rodents on islands: Genetic consequences of colonization and prospects for localized synthetic gene drive
16657K. P. Oh, A. B. Shiels, L. Shiels, D. V. Blondel, K. J. Campbell, J. R. Saah, A. L. Lloyd, P. Q. Thomas, F. Gould, Z. Abdo, J. R. Godwin and A. J. Piaggio, Evolutionary Applications, 2021-02-22 17:41:41.
Here we used pooled whole-genome sequencing of invasive mouse (Mus musculus) populations on four islands along with paired putative source populations to test genetic predictions of island colonization and characterize locally fixed Cas9 genomic targets. Patterns of variation across the genome reflected marked reductions in allelic diversity in island populations and moderate to high degrees of differentiation from nearby source populations despite relatively recent colonization. Locally fixed Cas9 sites in female fertility genes were observed in all island populations, including a small number with multiplexing potential. In practice, rigorous sampling of presumptive LFA will be essential to fully assess risk of resistance alleles. These results should serve to guide development of improved, spatially limited gene drive design in future applications.
ReMOT Control Delivery of CRISPR-Cas9 Ribonucleoprotein Complex to Induce Germline Mutagenesis in the Disease Vector Mosquitoes Culex pipiens pallens (Diptera: Culicidae)
17482X. X. Li, Y. Xu, H. B. Zhang, H. T. Yin, D. Zhou, Y. Sun, L. Ma, B. Shen and C. L. Zhu, Journal of Medical Entomology, 58. 2021-02-16 14:57:35.
The wide distribution of Culex (Cx.) pipiens complex mosquitoes makes it difficult to prevent the transmission of mosquito-borne diseases in humans. Gene editing using CRISPR/Cas9 is an effective technique with the potential to solve the growing problem of mosquito-borne diseases. This study uses the ReMOT Control technique in Culex pipiens pallens (L.) to produce genetically modified mosquitoes. A microinjection system was established by injecting 60 adult female mosquitoes-14 mu l injection mixture was required, and no precipitation occurred with <= 1 mu l of endosomal release reagents (chloroquine or saponin). The efficiency of delivery of the P2C-enhanced green fluorescent protein-Cas9 (P2C-EGFP-Cas9) ribonucleoprotein complex into the ovary was 100% when injected at 24 h post-bloodmeal (the peak of vitellogenesis). Using this method for KMO knockout, we found that gene editing in the ovary could also occur when P2C-Cas9 RNP complex was injected into the hemolymph of adult Cx. pipiens pallens by ReMOT Control. In the chloroquine group, of the 2,251 G(0) progeny screened, 9 individuals showed with white and mosaic eye phenotypes. In the saponin group, of the 2,462 G(0) progeny screened, 8 mutant individuals were observed. Sequencing results showed 13 bp deletions, further confirming the fact that gene editing occurred. In conclusion, the successful application of ReMOT Control in Cx. pipiens pallens not only provides the basic parameters (injection parameters and injection time) for this method but also facilitates the study of mosquito biology and control.
Optimized CRISPR tools and site-directed transgenesis in Culex quinquefasciatus mosquitoes for gene drive development
16372X. Feng, V. Lopez Del Amo, E. Mameli, M. Lee, A. L. Bishop, N. Perrimon and V. M. Gantz, bioRxiv, 2021.02.10.430702. 2021-02-11 20:33:00.
Here, we developed a Culex-specific Cas9/gRNA expression toolkit and used site-directed homology-based transgenesis to generate and validate a Culex quinquefasciatus Cas9-expressing line. We showed that gRNA scaffold variants improve transgenesis efficiency in both Culex and Drosophila and boost gene-drive performance in the fruit fly. These findings support future technology development to control Culex mosquitoes and provide valuable insight for improving these tools in other species.
Projects to target a range of pest control solutions
16366K. McCormack, The Chronicle, 2021-02-10 20:19:28.
With the annual national cost of established vertebrate pest animals estimated to be around $800 million, and over $4 billion for weeds, it’s in Australia’s best interest to try and tackle these pesky problems at their root causes. 19 projects will be funded following a competitive grant process to research and advance breakthrough solutions to control some of Australia’s worst established pest animals and weeds, including fall armyworm and prickly acacia. Minister for Agriculture, Drought and Emergency Management, David Littleproud, said he was delighted with the high calibre and diversity of projects coming from the popular grant round.
Oxitec gears up for test releases
16386T. O'Hara, Keynews.com, 2021-02-10 15:10:19.
The United Kingdom-based biotech company Oxitec will soon announce the test locations and timetable for releasing its genetically modified mosquitoes in the Florida Keys.
Number of Project Wolbachia mosquitoes released is constantly reviewed to maintain suppression of dengue: NEA
16388N. L. Ching, today, 2021-02-09 15:12:34.
Project Wolbachia – Singapore has yielded promising results so far.Releases of non-biting male Wolbachia-Aedes mosquitoes have suppressed the urban Aedes aegypti mosquito populations in study sites at Tampines and Yishun by up to 90 per cent, and we have observed 58 to 74 per cent less dengue cases in 2020 in areas where releases have been ongoing for at least a year compared to areas without releases. However, this does not mean that there will be no dengue cases in the study sites, especially in the initial period, because it takes several months for the releases to bring down the dengue mosquito population.While some residents at the release sites have noticed more non-biting mosquitoes around their homes, the released male mosquitoes do not bite, and the overall data shows a clear benefit — fewer dengue cases.
Public attitudes towards synthetic biology
16363CSIRO, Synthetic Biology Future Science Platform, 2021-02-08 20:06:39.
A national survey has been conducted by CSIRO’s Synthetic Biology Future Science Platform as an important first step in measuring public attitudes towards synthetic biology. The survey draws on the views of more than 8,000 Australians, and researchers are examining the data to determine current attitudes to these emerging technologies
GeneConvene Global Collaborative Webinar Series | Genetic Biocontrol 2021
16249David O'Brochta and Hector Quemada, GeneConvene Global Collaborative, 2021-02-05 21:53:11.
In the mid 20th century various ideas emerged concerning how genetics and genetic principles could be directly applied to age-old problems of managing insects that threaten food security and public health. This series of webinars will explore the current state-of-the-art of what has been termed genetic control, genetic pest management and genetic biocontrol. It will cover the use of sterility, conditional dominant lethality and Wolbachia-induced cytoplasmic incompatibility. Gene drive, another type of genetic biocontrol, will not be covered in this series; it was recently the focus of webinar series dedicated to the topic.
How to engage communities on a large scale? Lessons from World Mosquito Program in Rio de Janeiro, Brazil [version 2; peer review: 1 approved, 2 approved with reservations]
16361G. B. Costa, R. Smithyman, S. L. O'Neill and L. A. Moreira, Gates Open Research, 2021-02-04 19:26:09.
Here we discuss and analyse the framework for community engagement implemented by the WMP in Brazil, during the large-scale deployment of the method in the municipalities of Niterói and Rio de Janeiro, Brazil. Our experience indicates that the community engagement work for arboviruses control should be understood as an opportunity for local development. It is necessary, based on an integrated analysis of the territory, to understand that the actions for arboviruses control could be a catalyst for the necessary socioenvironmental, cultural and public health changes. Furthermore, it is essential to understand that community engagement goes beyond informing or asking for population consent, but it constitutes a possibility for dialogue and exchange between the various stakeholders present in the territories, to build on cooperation for mosquito-borne disease control.
Reply to: Issues with combining incompatible and sterile insect techniques
16265Y. Li, L. A. Baton, D. Zhang, J. Bouyer, A. G. Parker, A. A. Hoffmann, L. C. Ng, C. H. Tan and Z. Xi, Nature, 590:E3-E5. 2021-02-04 16:31:29.
When the aim is elimination of the target population, Uni-CI and Bi-CI do not have appreciably different risks of population replacement. The small-scale field trial8 cited by Moretti and Calvitti in their Comment1 does not provide evidence that Bi-CI protects against population replacement during IIT, as the occurrence of the released Wolbachia strain in the field was not determined and the level of population suppression was insufficient to facilitate surpassing of the invasion threshold.
The complete mitogenome sequence of the agricultural pest, clover root weevil: the key to its own demise?
18799R. A. Al-Jiab, J. Gillum, A. Alexander, D. M. Tompkins, C. B. Phillips, P. K. Dearden and N. J. Gemmell, Mitochondrial DNA Part B, 4:878-879. 2021-02-03 18:44:34.
AbstractWe report the complete mitogenome of Sitona obsoletus, an agricultural pest in New Zealand and some European countries. Like other Sitona mitogenomes, the 6 tRNA gene box is ordered RNSAEF, supporting the hypothesis that this signature is common to, and potentially diagnostic, of this genus. The Trojan Female Technique (TFT) is a genetic pest control strategy that exploits mitochondrial DNA alleles that affect male, but not female fertility and fitness. The complete mitogenome is an essential first step in exploring the utility of TFT for the control of S. obsoletus.
Grey squirrels: is birth control the solution to Britain’s invasive species problem?
16275J. Gilchrist, The Conversation, 2021-02-03 17:03:29.
As with the UK’s other invasive species, such as rabbits, signal crayfish and Japanese knotweed, introducing the grey squirrel has proved to be an expensive mistake. Not only do grey squirrels displace red squirrels, they strip bark from trees. A recent report estimated that this could cost commercial forestry and native woodlands £1.1 billion (US$1.5 billion) over the next 40 years, including revenue lost to damaged timber, reduced carbon storage, tree replacement costs and squirrel control. Despite efforts to kill grey squirrels over several decades, their populations remain large and widespread.
Issues with combining incompatible and sterile insect techniques
16261R. Moretti and M. Calvitti, Nature, 590:E1-E2. 2021-02-03 16:00:45.
In a recent paper, Zheng at al.1 performed field experiments that tested a strategy of mosquito suppression based on the release of functionally sterile males produced by the combination of reproductive unidirectional cytoplasmic incompatibility (which is induced by the bacterium Wolbachia) and a sterilization treatment caused by X-rays. In our opinion, the authors do not present an exhaustive description of the current status in this field, and their results highlight several practical weaknesses in this strategy.
Mosquitoes genetically modified to be resistant to Zika
16259Staff, Lab+Life Scientist, 2021-02-02 15:55:50.
Researchers have wrestled with different strategies for controlling the spread of Zika virus, which is transmitted to humans from female mosquito bites. One approach, which has been approved by the US Environmental Protection Agency, will see more than 750 million genetically modified mosquitoes released into the Florida Keys in 2021 and 2022. These ‘suicide mosquitoes’ are genetically altered to produce offspring that die before emerging into adults and therefore cannot bite humans and spread disease.
Improving the Phenotypic Properties of the Ceratitis capitata (Diptera: Tephritidae) Temperature-Sensitive Lethal Genetic Sexing Strain in Support of Sterile Insect Technique Applications
16226M. F. Porras, J. S. Meza, E. G. Rajotte, K. Bourtzis and C. Caceres, Journal of Economic Entomology, 113:2688-2694. 2021-01-31 16:33:01.
We present the first evidence that this slower development is due to a different gene, here namely slow development (sd), which is closely linked to the tsl gene. Taking advantage of recombination phenomena between the two loci, we report the isolation of a novel temperature sensitivity lethal strain using the wp mutation as a morphological marker, which showed faster development (wp tsl FD) during the larval stage and increased in its temperature sensitivity compared with the normal tsl strain. Moreover, the introgression of this novel wp tsl FD combined trait into the Vienna 8(D53-) GSS, resulted in a novel Vienna 8(D53-) FD GSS, where females showed differences in the thermal sensibility, larval development speed, and productivity profiles. The modification of these traits and their impact on the mass rearing of the GSS for sterile insect technique applications are discussed.
Project Wolbachia: Residents are killing the ‘helpful’ mosquitoes, which can be a nuisance
16228T. J. Cheng, today, 2021-01-29 16:33:12.
In 2019, Dr Amy Khor, then Senior Minister of State for the Environment and Water Resources, said that there was a 90 per cent suppression rate at study sites in Tampines and Yishun from February to November that year. However, certain public housing estates under the project were still dengue hot zones last year.The idea of the project is to have the male Aedes mosquitoes, which are injected with the Wolbachia bacteria, mate with female Aedes aegypti mosquitoes. The females then go on to lay eggs that do not hatch, effectively suppressing their numbers.
Demographic feedbacks can hamper the spatial spread of a gene drive
16203L. Girardin and F. Débarre, arXiv, 2021-01-27 15:32:53.
Our results indicate that taking into account the interplay between population dynamics and population genetics might actually be crucial, as it can effectively reverse the direction of the invasion and lead to failure. Our findings can be extended to other bistable systems, such as the spread of cytoplasmic incompatibilities caused by Wolbachia.
Playing God and tampering with nature: popular labels for real concerns in synthetic biology
16201L. Carter, A. Mankad, E. V. Hobman and N. B. Porter, Transgenic Research, 2021-01-27 15:26:41.
We present the findings from a large Australian study (N = 4593) which suggests ‘playing God’ objections and their variants can be multilayered and, at times, accompanied by meaningful information about risk perceptions. We use qualitative analysis of ope
RNAi-based products: A sustainable alternative to hazardous pesticides
16211Ghent University, Phys Org, 2021-01-27 13:59:48.
RNAi-based biocontrol is a great alternative to hazardous pesticides and can contribute towards reversing the alarming decline in farmland birds and beneficial insects (especially pollinating ones). RNAi is a well-known natural biological process in most
Genetically-modified mosquitoes key to stopping Zika virus spread
16208University of Missouri, Medical Xpress, 2021-01-26 13:52:44.
Alexander Franz, an associate professor in the MU College of Veterinary Medicine, collaborated with researchers at Colorado State University by using CRISPR gene-editing technology to produce mosquitoes that are unable to replicate Zika virus and therefore cannot infect a human through biting. "We genetically manipulated these mosquitoes by inserting an artificial gene into their genome that triggers one of the immune pathways in the midgut to recognize and destroy the RNA genome of Zika virus," Franz said. "By developing these mosquitoes that are resistant to the virus, the disease cycle is interrupted so transmission to humans can no longer take place." Franz added that the genetic modification is inheritable, so future generations of the altered mosquitoes would be resistant to Zika virus as well.
Drivers of mosquito mating
16110N. C. Manoukis, Science, 371:340. 2021-01-22 15:54:49.
Gene drive systems are based on the release of organisms whose genomes have been modified or engineered to spread a desired allele or trait (such as resistance to the parasites that cause malaria) through a population. Success will depend on the release of genetically modified males that will be able to mate with wild females. Beyond gene drive strategies, in mosquitoes it is understood that only males can be released as part of any genetic pest control (GPC) program (7); females feed on blood to lay eggs, and releasing insects that will feed on humans is widely unacceptable.
Clock genes and environmental cues coordinate Anopheles pheromone synthesis, swarming, and mating
16108G. Wang, J. Vega-Rodríguez, A. Diabate, J. Liu, C. Cui, C. Nignan, L. Dong, F. Li, C. O. Ouedrago, A. M. Bandaogo, P. S. Sawadogo, H. Maiga, T. L. Alves e Silva, T. V. Pascini, S. Wang and M. Jacobs-Lorena, Science, 371:411. 2021-01-22 15:35:30.
Knockdown of per and tim expression affects Anopheles gambiae s.s. and Anopheles stephensi male mating in the laboratory, and it reduces male An. coluzzii swarming and mating under semifield conditions. Light and temperature affect mosquito mating, possibly by modulating per and/or tim expression. Moreover, the desaturase gene desat1 is up-regulated and rhythmically expressed in the heads of swarming males and regulates the production of cuticular hydrocarbons, including heptacosane, which stimulates mating activity.
The Promises and Realities of Integration in Synthetic Biology: A View From Social Science
16287L. Carter and A. Mankad, Frontiers in Bioengineering and Biotechnology, 8. 2021-01-21 17:25:32.
We take stock of thepromises and realities of science integration by sharing our experiences of embarking onthis very challenge in Australia. We conclude by offering suggestions for bringing aboutthe enabling conditions for improved integration across the natural and social sciences.Four key actions are articulated to help pivot synthetic biology toward a more integratedscientific endeavor: (a) formalizing inclusivity from inception to project conclusion; (b)valuing differing philosophical positions as a strength rather than a barrier; (c) acceptingthat integration takes persistence and communication but is immensely rewarding; and(d) promoting meaningful interactions, such as pursuing joint opportunities, co-designingand co-publishing research. We argue that these actions arekey enablers for realizingscience integration in synthetic biology.
Co‐developing a common glossary with stakeholders for engagement on new genetic approaches for malaria control in a local African setting
16104E. Chemonges Wanyama, B. Dicko, L. Pare Toe, M. B. Coulibaly, N. Barry, K. Bayala Traore, A. Diabate, M. Drabo, J. K. Kayondo, S. Kekele, S. Kodio, A. D. Ky, R. R. Linga, E. Magala, W. I. Meda, S. Mukwaya, A. Namukwaya, B. Robinson, H. Samoura, K. Sanogo, Malaria Journal, 20:53. 2021-01-21 14:51:47.
Scientific terminologies are mainly lacking in local languages, yet when research activities involve international partnership, the question of technical jargon and its translation is crucial for effective and meaningful communication with stakeholders. Target Malaria, a not-for-profit research consortium developing innovative genetic approaches to malaria vector control, carried out a linguistic exercise in Mali, Burkina Faso and Uganda to establish the appropriate translation of its key terminology to local languages of sites where the teams operate.
Combining refuges with transgenic insect releases for the management of an insect pest with non-recessive resistance to Bt crops in agricultural landscapes
17006T. R. Brewer and M. B. Bonsall, Journal of Theoretical Biology, 509:11. 2021-01-21 12:35:03.
Reinforcing the high-dose/refuge strategy with releases of transgenic insects has been suggested as a method for simultaneously managing agricultural pest populations and resistance to transgenic crops. Theoretical and empirical studies have shown that these approaches can work when deployed against closed populations and the assumptions of the HDR strategy are met. However, field-evolved resistance is often linked to non-recessive resistance or refuge non-compliance, and pest management regimes are likely to take place at the landscape-level. It is therefore important to understand how effective such strategies are when resistance is non-recessive, and how they could be employed in agricultural landscapes. We developed a spatially-explicit model to investigate the efficacy of strategies combining refuges with transgenic insect releases to manage a pest with non-recessive resistance in agricultural landscapes. We compared two release strategies, area-wide releases and localised releases targeted at population hotspots, and analysed the effects of refuge and release parameters on population and resistance dynamics. Area-wide releases reliably achieved landscape-level pest eradication. Localised releases also eradicated the pest when low release thresholds were combined with high release ratios, and maintained the pest at low densities when insufficient to achieve extinction. Reinforcing refuges with localised releases also greatly enhanced the probability of resistance extinction. However, when resistance remained in the population, localised releases prevented resistance from reaching fixation rather than greatly delaying or reversing resistance evolution. Our work indicates that combining refuges with simple release policies is effective for landscape-level pest suppression when the HDR assumptions are violated, but more nuanced release strategies may be required to enhance the benefits to resistance management. (C) 2020 Elsevier Ltd. All rights reserved.
Manipulation of Gut Symbionts for Improving the Sterile Insect Technique: Quality Parameters of Bactrocera dorsalis (Diptera: Tephritidae) Genetic Sexing Strain Males After Feeding on Bacteria-Enriched Diets
17222Q. Zhang, P. Cai, B. Wang, X. Liu, J. Lin, R. Hua, H. Zhang, C. Yi, X. Song, Q. Ji, J. Yang and S. Chen, Journal of Economic Entomology, 114:560-570. 2021-01-18 16:16:41.
One environmentally friendly method used to manage Bactrocera dorsalis (Hendel), a key agricultural pest of substantial economic importance, is the sterile insect technique (SIT). Nevertheless, several deficiencies related to this strategy impair the success of the SIT, including the inferior performance of released sterile males compared with wild males, which could be partly solved by the utilization of gut symbionts as probiotic dietary components. In this study, a culture-dependent method was used to isolate and characterize gut-associated bacterial species in adult B. dorsalis genetic sexing strain (GSS) males. In addition, three bacterial isolates from the Enterobacteriaceae family, namely, Enterobacter sp., Morganella morganii, and Moellerella wisconsensis, were used as supplements in larval and adult diets to assess their effects on the life-history traits of irradiated males. Consistent with many previous studies, Enterobacter spp. was shown to be beneficial, with some quality control indices, such as adult size, pupal weight, survival rate under stress and nutritionally rich conditions, and mating competitiveness, being significantly increased, while slight nonsignificant increases in emergence rate and flight ability were observed. Conversely, the M. morganii and M. wisconsensis strains both had negative effects on irradiated male fitness and mating competitiveness. Our results, in combination with those of earlier studies, can contribute to improving the effectiveness of SIT application by enhancing the different aspects of augmentative rearing and biological traits of pests under laboratory rearing conditions.
Responsibly Developing Gene Drives: The GeneConvene Global Collaborative
15969J. Toomey, Bill of Health, 2021-01-13 19:18:06.
The GeneConvene Global Collaborative, a project of the Foundation for the National Institutes of Health, was started this past July to promote the responsible development and regulation of gene drive technologies. It brings together researchers, regulators and stakeholders around the world to develop best practices for gene drive research and implementation. Because of my prior writing on this topic, I participated in GeneConvene’s fall webinar series and spoke with scientists there about the project. Debates about the regulation of gene drives are unique in several respects, because the technology is unique in several respects.
‘Clever Approach’: Scientists Create GM-Free Organisms Using Genetic Engineering
15955A. Paleja, The WIRE, 2021-01-11 17:07:06.
Farther to the north, researchers at the University of Minnesota have developed a novel way to resolve this problem. They used genetic engineering to create organisms for release that are not genetically modified. Maciej Maselko was a postdoctoral associate at the university when he was part of the study. “Slow and expensive regulatory approvals for GM insect release” inspired the team’s work, he told The Wire Science. “We looked for a way to get the benefits achieved with GM insect release but without needing to release GM insects.” He conceptualised the experiment with PhD scholar Siba Das and molecular biology professor Michael Smanski. The results were published in November 2020. In a typical control intervention, researchers release sterile male mosquitoes into the environment. These compete with wild males to mate with wild females. Mosquitoes mate only once in their lifetime. Since mating with sterile mosquitoes produces no offspring, the local mosquito population begins to fall. The methods to select these male mosquitoes to subsequently release are either labour intensive or need specialised equipment. The colony that scientists rear is also often three times larger than the number of males released. Third, a mosquito lives typically for 8-10 days. So scientists must select the males to release close to the site of intervention.
Population Dynamics of Aedes aegypti and Aedes albopictus in Two Rural Villages in Southern Mexico: Baseline Data for an Evaluation of the Sterile Insect Technique
17758C. F. Marina, J. G. Bond, K. Hernández-Arriaga, J. Valle, A. Ulloa, I. Fernández-Salas, D. O. Carvalho, K. Bourtzis, A. Dor, T. Williams and P. Liedo, Insects, 12. 2021-01-11 14:36:35.
Indoor and outdoor ovitraps were placed in 15 randomly selected houses in two rural villages in Chiapas, southern Mexico. In addition, ovitraps were placed in five transects surrounding each village, with three traps per transect, one at the edge, one at 50 m, and another at 100 m from the edge of the village. All traps were inspected weekly. A transect with eight traps along a road between the two villages was also included. Population fluctuations of Aedes aegypti and Ae. albopictus were examined during 2016–2018 by counting egg numbers. A higher number of Aedes spp. eggs was recorded at Hidalgo village with 257,712 eggs (60.9%), of which 58.1% were present in outdoor ovitraps and 41.9% in indoor ovitraps, compared with 165,623 eggs (39.1%) collected in the village of Río Florido, 49.0% in outdoor and 51.0% in indoor ovitraps. A total of 84,047 eggs was collected from ovitraps placed along transects around Río Florido, compared to 67,542 eggs recorded from transects around Hidalgo. Fluctuations in egg counts were associated with annual variation in precipitation, with 2.3 to 3.2-fold more eggs collected from ovitraps placed in houses and 4.8 to 5.1-fold more eggs in ovitraps from the surrounding transects during the rainy season than in the dry season, respectively. Aedes aegypti was the dominant species during the dry season and at the start of the rainy season in both villages. Aedes albopictus populations were lower for most of the dry season, but increased during the rainy season and predominated at the end of the rainy season in both villages. Aedes albopictus was also the dominant species in the zones surrounding both villages. The numbers of eggs collected from intradomiciliary ovitraps were strongly correlated with the numbers of eggs in peridomiciliary ovitraps in both Río Florido (R2adj = 0.92) and Hidalgo (R2adj = 0.94), suggesting that peridomiciliary sampling could provide an accurate estimate of intradomiciliary oviposition by Aedes spp. in future studies in these villages. We conclude that the feasibility of sterile insect technique (SIT)-based program of vector control could be evaluated in the isolated Ae. aegypti populations in the rural villages of our baseline study.
CRISPR and the splice to survive: New gene-editing technology could be used to save species from extinction—or to eliminate them.
16011E. Kolbert, New Yorker, 2021-01-11 14:25:59.
About a year ago, not long before the pandemic began, I paid a visit to the center, which is an hour southwest of Melbourne. The draw was an experiment on a species of giant toad known familiarly as the cane toad. The toad was introduced to Australia as an agent of pest control, but it promptly got out of control itself, producing an ecological disaster. Researchers at the A.C.D.P. were hoping to put the toad back in the bottle, as it were, using crispr.
Next-generation tools to control biting midge populations and reduce pathogen transmission
15940P. Shults, L. W. Cohnstaedt, Z. N. Adelman and C. Brelsfoard, Parasites and Vectors, 14:31. 2021-01-07 14:52:23.
Biting midges of the genus Culicoides transmit disease-causing agents resulting in a significant economic impact on livestock industries in many parts of the world. Localized control efforts, such as removal of larval habitat or pesticide application, can be logistically difficult, expensive and ineffective if not instituted and maintained properly. With these limitations, a population-level approach to the management of Culicoides midges should be investigated as a means to replace or supplement existing control strategies. Next-generation control methods such as Wolbachia- and genetic-based population suppression and replacement are being investigated in several vector species. Here we assess the feasibility and applicability of these approaches for use against biting midges. We also discuss the technical and logistical hurdles needing to be addressed for each method to be successful, as well as emphasize the importance of addressing community engagement and involving stakeholders in the investigation and development of these approaches.
Mosquito Sexual Selection and Reproductive Control Programs
15921L. J. Cator, C. A. S. Wyer and L. C. Harrington, Trends in Parasitology, 2021-01-06 18:45:40.
Recent work has generated many key insights about specific aspects of mating behavior and physiology. Here, we synthesize these findings and classify swarming mosquito systems as polygynous. Male mating success is highly variable in swarms and evidence suggests that it is likely determined by both scramble competition between males and female choice. Incorporating this new understanding will improve both implementation and long-term stability of reproductive control tools.
ARS Science Key to Stopping ‘Man-Eating’ Parasite
15973S. Elliott, Tellus, 2021-01-04 19:30:15.
Screwworm infestations were once prevalent in the United States, with 230,000 cases reported in 1935 alone. ARS scientists Edward Knipling and Raymond Bushland conceived and developed the sterile insect technique (SIT) to control and eradicate screwworms. With SIT, sterilized male blow flies were released to breed with wild flies. Since female blow flies mate only once, the coupling effectively removed that female and her potential offspring from the population.
Conservation pest control with new technologies: public perceptions
15913E. A. MacDonald, M. B. Neff, E. Edwards, F. Medvecky and J. Balanovic, Journal of the Royal Society of New Zealand, 2021-01-04 13:45:38.
We conducted eleven focus groups in New Zealand to explore three questions about novel technologies (gene drive and two others for comparison of pest control tools): (1) what are the risks/benefits? (2) how do they compare to current methods? and (3) who should be represented on a panel that evaluates the tools and what factors should they consider?
His Passion Was Contagious
15928D. C. McCool, Notre Dame Magazine, 2021-01-01 19:03:35.
Craig was an entomologist and vector biologist whose interest in mosquitoes and the diseases they transmit to people was as contagious as the pathogens themselves. Hesburgh could not have chosen a more driven faculty member. In his 38 years at Notre Dame, before he died in 1995 at an Entomology Society of America conference in Las Vegas, Craig cultivated a legacy in a field that was in its infancy. His personality attracted even more people dedicated to eliminating mosquito-borne diseases, and the circle widened in unexpected ways. The Chicago native directed more than 40 doctoral students and mentored 38 postdoctoral researchers. He created Notre Dame’s Vector Biology Laboratory — vectors pass diseases from one organism to another — with a focus on the Aedes genus of mosquitoes. He became Notre Dame’s first member of the prestigious National Academy of Sciences (NAS). And he developed a program that has turned out hundreds of new field biologists who have gone onto careers in academia and public health.
Transgenic cotton and sterile insect releases synergize eradication of pink bollworm a century after it invaded the United States
15697B. E. Tabashnik, L. R. Liesner, P. C. Ellsworth, G. C. Unnithan, J. A. Fabrick, S. E. Naranjo, X. Li, T. J. Dennehy, L. Antilla, R. T. Staten and Y. Carrière, Proceedings of the National Academy of Sciences, 118:e2019115118. 2020-12-28 18:26:42.
The program included releases of billions of sterile pink bollworm moths from airplanes and planting of cotton engineered to produce insect-killing proteins from the bacterium Bacillus thuringiensis. Analysis of computer simulations and 21 y of field data from Arizona indicate these two tactics interacted synergistically to suppress the pest. By eradicating the pink bollworm, the program ended the damage it caused to cotton and the insecticide sprays used to control it, yielding economic, environmental, and social benefits.Invasive organisms pose a global threat and are exceptionally difficult to eradicate after they become abundant in their new habitats.
Genetic pest management and the background genetics of release strains
15695P. T. Leftwich, L. G. Spurgin, T. Harvey-Samuel, C. J. E. Thomas, L. C. Paladino, M. P. Edgington and L. Alphey, Philosophical Transactions of the Royal Society B: Biological Sciences, 376:20190805. 2020-12-28 15:35:20.
We discuss issues around strain selection and the potential consequences of such introgression. We conclude that such introgression is probably harmless in almost all circumstances, and could, in theory, provide specific additional benefits to the release programme. We outline population monitoring approaches that could be used, going forward, to determine how background genetics may affect GPM. This article is part of the theme issue ‘Novel control strategies for mosquito-borne diseases’.
Genetic sexing strains for the population suppression of the mosquito vector Aedes aegypti
15691P. Koskinioti, A. A. Augustinos, D. O. Carvalho, M. Misbah-ul-Haq, G. Pillwax, L. D. d. l. Fuente, G. Salvador-Herranz, R. A. Herrero and K. Bourtzis, Philosophical Transactions of the Royal Society B: Biological Sciences, 376:20190808. 2020-12-28 15:27:53.
Here, we report on the construction of two genetic sexing strains using red- and white-eye colour mutations as selectable markers. Quality control analysis showed that the Red-eye genetic sexing strains (GSS) is better and more genetically stable than the White-eye GSS. The introduction of an irradiation-induced inversion (Inv35) increases genetic stability and reduces the probability of female contamination of the male release batches. Bi-weekly releases of irradiated males of both the Red-eye GSS and the Red-eye GSS/Inv35 fully suppressed target laboratory cage populations within six and nine weeks, respectively
Wolbachia strain wAlbB maintains high density and dengue inhibition following introduction into a field population of Aedes aegypti
15689N. A. Ahmad, M.-V. Mancini, T. H. Ant, J. Martinez, G. M. R. Kamarul, W. A. Nazni, A. A. Hoffmann and S. P. Sinkins, Philosophical Transactions of the Royal Society B: Biological Sciences, 376:20190809. 2020-12-28 15:06:28.
Here, wAlbB-carrying Ae. aegypti collected from the field 20 months after the cessation of releases showed no reduction in Wolbachia density or tissue distribution changes compared to a wAlbB laboratory colony. The wAlbB strain continued to induce complete unidirectional cytoplasmic incompatibility, showed perfect maternal transmission under laboratory conditions, and retained its capacity to inhibit dengue. Additionally, a field-collected wAlbB line was challenged with Malaysian dengue patient blood, and showed significant blocking of virus dissemination to the salivary glands.
CRISPR/Cas9 knockout of female-biased genes AeAct-4 or myo-fem in Ae. aegypti results in a flightless phenotype in female, but not male mosquitoes
15617S. O’Leary and Z. N. Adelman, PLOS Neglected Tropical Diseases, 14:e0008971. 2020-12-18 16:05:35.
Author summary Ae. aegypti is the most important vector of arboviruses throughout the world, and new strategies are urgently needed to add to our existing arsenal of control methods to prevent or halt disease transmission. Importantly, only female Ae. aegypti mosquitoes transmit arboviruses due to their need for vertebrate blood to support egg production. Here, we identify several genes that are critical only for female mosquito flight; genetic ablation of each gene resulted in flightless females, but flying males. Importantly, the female flightless phenotype was completely penetrant (100%), and the use of sex-biased flight muscle proteins appeared to be conserved throughout mosquito evolution. These data could be used to support the development of novel genetic control approaches to reduce the number of biting females across a wide range of disease vector species.
Precise single base substitution in the shibire gene by CRISPR/Cas9-mediated homology directed repair in Bactrocera tryoni
16693A. Choo, E. Fung, I. Y. Chen, R. Saint, P. Crisp and S. W. Baxter, BMC Genetics, 21. 2020-12-18 15:58:10.
Here we introduce a known Drosophila melanogaster temperature sensitive embryonic lethal mutation into Bactrocera tryoni, a serious horticultural pest in Australia. A non-synonymous point mutation in the D. melanogaster gene shibire causes embryonic lethality at 29 degrees C and we successfully used CRISPR/Cas9 technology to recreate the orthologous shibire temperature sensitive-1 (shi(ts1)) mutation in B. tryoni. Genotypic analyses over three generations revealed that a high fitness cost was associated with the shi(ts1) mutant allele and shi(ts1) homozygotes were not viable at 21 degrees C, which is a more severe phenotype than that documented in D. melanogaster.ConclusionsWe have demonstrated the first successful use of CRISPR/Cas9 to introduce precise single base substitutions in an endogenous gene via homology-directed repair in an agricultural pest insect and this technology can be used to trial other conditional mutations for the ultimate aim of generating genetic sexing strains for SIT.
Converting female mosquitoes to non-biting males with implications for mosquito control
15614M. V. Candy, Vet Candy, 2020-12-18 15:57:05.
Virginia Tech researchers have proven that a single gene can convert female Aedes aegypti mosquitoes into fertile male mosquitoes and identified a gene needed for male mosquito flight. Male mosquitoes do not bite and are unable to transmit pathogens to humans. Female mosquitoes, on the other hand, are able to bite. Female Aedes aegypti mosquitoes require blood to produce eggs, making them the prime carriers of the pathogens that cause Zika and dengue fever in humans. "The presence of a male-determining locus (M locus) establishes the male sex in Aedes aegypti and the M locus is only inherited by the male offspring, much like the human Y chromosome," said Zhijian Tu, a professor in the Department of Biochemistry in the College of Agriculture and Life Sciences. "By inserting Nix, a previously discovered male-determining gene in the M locus of Aedes aegypti, into a chromosomal region that can be inherited by females, we showed that Nix alone was sufficient to convert females to fertile males. This may have implications for developing future mosquito control techniques." These findings were published in the Proceedings of the National Academy of Sciences.
New insect species made via genetic engineering
15610L. Leffer, SCIENCELINE, 2020-12-18 15:47:16.
A biotech fast-forward button for evolution is on the horizon. Researchers say they have used a novel genetic engineering method to create several new species of fruit fly in the lab for the first time — an achievement which might help put a future without malaria and other insect-borne diseases within reach. The approach, called synthetic speciation, could prove useful in creating safer pest-control technologies, says Maciej Maselko, a postdoctoral fellow studying synthetic biology at Macquarie University. In one far-off scenario, according to Maselko, synthetic speciation might even be applied to generate designer organisms that could pollinate plants or even detect landmines. Maselko and his team published their findings September 8 in Nature Communications. “Speciation has occurred billions of times on the planet, but hasn’t been engineerable [before],” says Michael Smanski, a molecular biologist at the University of Minnesota and member of the research team. Maselko, Smanski and their colleagues have previously used a similar method to engineer “species like” differences in yeast in 2018, but their more recent results are the first time the concept has been proven possible in a multicellular animal. This method could produce untold numbers of new animal varieties within months rather than millennia, Smanski says.
FKMCD – Oxitec | Mosquito Project Webinar Series
15564Oxitec Ltd, FKMCD and Oxitec, 2020-12-18 15:43:23.
This FKMCD - Oxitec Public Educational Webinar, our ninth, shows how Oxitec's just-add-water technology helps control the Aedes aegypti mosquito population. The second half of the webinar includes questions and answers with attendees.
Fear of Oxitec mosquito release grows
15541T. Java, Florida Keys Free Press, 2020-12-16 20:11:11.
A local effort has emerged to exclude Key Largo from a test release of genetically modified Aedes aegypti mosquitoes planned for the spring. The U.S. Environmental Protection Agency and the Florida Keys Mosquito Control District have approved a release of United Kingdom-based biotech company Oxitec’s GMO insects in an effort to battle the disease-carrying wild mosquito population by effectively breeding it out of existence.
A patent review on strategies for biological control of mosquito vector
15377K. Parihar, M. Telang and A. Ovhal, World Journal of Microbiology and Biotechnology, 36:23. 2020-12-09 20:28:33.
This paper presents a comprehensive technology overview of patent documents disclosing biological agents for mosquito control. The patent analysis revealed that comparable number of patent documents were filed in two technology categories: non-recombinant agents and genetically modified (GM) agents. In the category of non-recombinant agents, toxic peptides from microbes and biological consortia seemed to be the earliest technology noted right from the year 1965 whereas the patent filings for suppression of mosquito population using genetic modification techniques have emerged from the year 2000 onwards. The United States of America is the leading patent filing jurisdiction followed by China and the Great Britain. Academic institutes have filed higher number of patent applications as compared to private companies. University of Florida was found to be the leading patent filing entity and its patents were focused on suppression of vector population using techniques such as release of insects with dominant lethal (RIDL) and RNA interference (RNAi).
Targeting female flight for genetic control of mosquitoes
15310D. Navarro-Payá, I. Flis, M. A. E. Anderson, P. Hawes, M. Li, O. S. Akbari, S. Basu and L. Alphey, PLOS Neglected Tropical Diseases, 14:e0008876. 2020-12-03 20:11:01.
The yellow fever mosquito and the Southern house mosquito are important vectors of infectious diseases. Given their widespread presence across tropical and subtropical regions of the world and the increased risk of spread due to global warming there is a growing need for population control. Gene drives aim to spread a genetic element within target genes required for mosquito reproduction to disrupt their function and crash a population. Female-specific genes provide interesting candidates for population control since female mosquitoes determine the reproductive capacity of a population as well as being the actual vectors of disease. Here we describe a study on Actin-4 loss in both Aedes aegypti and Culex quinquefasciatus, where we observe female-specific disruption of flight ability and propose it as a candidate for genetic methods of population suppression.
Engineered Gene Drives and their Value in the Control of Vector-Borne Diseases, Weeds, Pests, and Invasive Species
15294K. Hefferon and R. Herring, GMOs: Implications for Biodiversity Conservation and Ecological Processes, 2020-12-02 17:10:55.
Genetic engineering has created potential for moving medical and agricultural research and application frontiers forward in unprecedented ways. Despite its accepted use as a powerful tool in medical research, genetic modification and genome editing technologies remain controversial in large-scale ecological intervention and open-field agriculture. Gene drive is a technology based on genome editing that enables a trait to be pushed through a given population at a greater than expected rate. While gene drives show enormous promise as a way to address a number of challenges, such as the reduction of populations of disease-spreading pests and invasive species, they also incite great social unease because of unknown risks. The following chapter describes the mechanics of gene drives and how they could be utilized to control vector-borne diseases, weeds, and crop pests and even protect populations of endangered species. Limitations and risks associated with gene drive technologies, such as containment strategies and potential resistance, are discussed. Finally, the social impacts of gene drives with respect to international governance and public acceptance are considered.
Genetically Engineered Fish: Potential Impacts on Aquaculture, Biodiversity, and the Environment
15290R. A. Dunham and B. Su, GMOs: Implications for Biodiversity Conservation and Ecological Processes, 2020-12-02 17:03:48.
Studies on transgenic fish for the aquaculture industry have focused on improving growth rates, enhancing disease resistance, altering body composition, acting as biological factories for medical proteins, and even altering temperature tolerance and coloration. The future impact of transgenesis will likely be quite large. Growth hormone-transgenic salmon has been approved for human consumption and has been introduced to the market in Canada and soon to the USA. This is the first human consumption of approved transgenic meat. Transgene insertion has many pleiotropic effects. Several studies have projected the fitness of transgenic fish to be low, in general, compared to non-transgenic and wild fish; thus, their environmental risk is likely low and they would have minimal, if any, long-term impact on ecosystems or biodiversity. However, there have been no actual escapements; thus, only projections of risk are available based on small-scale experiments and the characteristics of transgenic fish compared to controls. An active area of research is repressible transgenic sterilization and sterilization using gene editing, both of which would allow application of transgenic fish with only short-term consequences for ecosystems in the worst-case scenario. Transgenic technology could also be potentially used to reduce or eliminate populations of nuisance species.
Invasive Species Control and Resolution of Wildlife Damage Conflicts: A Framework for Chemical and Genetically Based Management Methods
15286L. Clark, J. Eisemann, J. Godwin, K. E. Horak, K. Oh, J. O’Hare, A. Piaggio, K. Pepin and E. Ruell, GMOs: Implications for Biodiversity Conservation and Ecological Processes, 2020-12-02 16:52:40.
Vertebrate wildlife damage management relates to developing and employing methods to mitigate against damage caused by wildlife in the areas of food production, property damage, and animal or human health and safety. Of the many management tools available
Strategic Approach, Advances, and Challenges in the Development and Application of the SIT for Area-Wide Control of Aedes albopictus Mosquitoes in Reunion Island
15267L. C. Gouagna, D. Damiens, C. F. Oliva, S. Boyer, G. Le Goff, C. Brengues, J.-S. Dehecq, J. Raude, F. Simard and D. Fontenille, Insects, 11:770. 2020-11-30 19:17:02.
Reply to: “Enhancement of Aedes aegypti susceptibility to dengue by Wolbachia is not supported”
15264C. Souto-Maior, J. G. King, L. M. Sartori, R. Maciel-de-Freitas and M. G. M. Gomes, Nature Communications, 11:6113. 2020-11-30 19:09:46.
Ant et al.4 claim that concerns with the data and broader analysis make our conclusions misleading. We herein respond to their comments by demonstrating the robustness of our results to different treatments of the data, and expand our arguments for replacing currently adopted methods by those introduced in our paper.
Enhancement of Aedes aegypti susceptibility to dengue by Wolbachia is not supported
15258T. H. Ant, M.-V. Mancini, J. Martinez and S. P. Sinkins, Nature Communications, 11:6111. 2020-11-30 18:48:33.
King et al.3 used DENV infection and transmission modelling to reinterpret experimental data from two previous studies4,5. The authors claimed that wMel Wolbachia increase the mean susceptibility of Ae. aegypti to DENV, contradicting various other studies6,7,8,9,10,11,12. Here, we raise concerns with the experimental approaches used to generate one of the primary datasets on which the modelling is based, and we discuss how these limitations could make some of the original conclusions misleading.
Combined Effects of Mating Disruption, Insecticides, and the Sterile Insect Technique on Cydia pomonella in New Zealand
15958R. M. Horner, P. L. Lo, D. J. Rogers, J. T. S. Walker and D. M. Suckling, Insects, 11:23. 2020-11-27 18:11:55.
We aimed to supplement these tactics with the sterile insect technique (SIT) to further suppress the codling moth on orchards. SIT involves mass rearing and sterilizing codling moth and then releasing them onto orchards where they mate with wild insects resulting in no offspring. We released sterile insects onto seven orchards using unmanned aerial vehicles and ground releases. Six years of the program saw significant drops (90-99%) in wild moth populations. The SIT is an excellent tactic for reducing moth populations in export apple orchards.
Split drive killer-rescue provides a novel threshold-dependent gene drive
15254M. P. Edgington, T. Harvey-Samuel and L. Alphey, Scientific Reports, 10. 2020-11-25 18:32:01.
Population genetics mathematical models are developed here to demonstrate the threshold-dependent nature of the proposed system and its robustness to imperfect homing, incomplete penetrance of toxins and transgene fitness costs, each of which are of practical significance given that real-world components inevitably have such imperfections. We show that although end-joining repair mechanisms may cause the system to break down, under certain conditions, it should persist over time scales relevant for genetic control programs. The potential of such a system to provide localised population suppression via sex ratio distortion or female-specific lethality is also explored. Additionally, we investigate the effect on introduction thresholds of adding an extra CRISPR base element, showing that this may either increase or decrease dependent on parameter context
Field Competitiveness of Aedes albopictus (Diptera: Culicidae) Irradiated Males in Pilot Sterile Insect Technique Trials in Northern Italy
16988R. Bellini, M. Carrieri, F. Balestrino, A. Puggioli, M. Malfacini and J. Bouyer, Journal of Medical Entomology, 58:807-813. 2020-11-20 14:50:15.
Vector-borne diseases account for 17% of infectious diseases, leading to more than one million deaths each year. Mosquitoes are responsible for 90% of the casualties and alternative control methods to insecticides are urgently needed, especially against Aedes vectors. Aedes albopictus is a particularly important species, causing major public health problems because it is a vector of several arboviruses and has a strong invasive behavior. Various genetic control methods have been proposed to be integrated into the management strategies of Aedes species, among which the sterile insect technique (SIT), which proved efficient against various insect pests and vectors. However, the ability of released irradiated sterile male mosquitoes to compete with their wild counterparts and induce sterility in wild females, which is critical to the success of this strategy, remained poorly defined. Here, we assessed the field competitiveness of Ae. albopictus irradiated male using data from eight release trials implemented in Northern Italy for 3 yr. Sterile males were capable of inducing a good level of sterility in the wild female population, however, with high variability in time and space. The field competitiveness of the released males was strongly negatively correlated with the ratio of sterile to wild males.This should be taken into consideration when designing future programs to suppress field populations of Aedes mosquitoes.
‘A plague to be reckoned with’: UMN research creates a buzz with invasive fruit fly research
15238B. Most, The Minnesota Daily, 2020-11-18 13:26:31.
n early November, assistant professor Mike Smanski published an article about a new breakthrough in this research, demonstrating for the first time this kind of genetic engineering was possible in the common fruit fly. This shows that researchers could engineer this work into spotted wing drosophila in the future. The University’s Smanski Lab has also studied this technique in mosquitoes, zebra fish and carp, but never with this type of fruit fly, he said. “These are all a new class of genetic pesticide, basically, that allow you to engineer the pest organism itself and convert that pest organism into the pesticide,” Smanski said. Through this work the researchers can create a pest that is biologically the same, but when the females mate with these genetically modified males, they will not produce viable offspring, he said. This sterile insect technique can be helpful not only in reducing the population of insects, but in reducing the impacts of insecticides on surrounding species and nearby ecosystems, said Feltman, a second-year biochemistry, molecular biology and biophysics graduate student.
Engineering biological diversity: the international governance of synthetic biology, gene drives, and de-extinction for conservation
15251J. L. Reynolds, Current Opinion in Environmental Sustainability, 49:1-6. 2020-11-17 18:23:24.
In the face of insufficient progress in conserving and restoring biodiversity, the in situ use of advanced genetic modification, gene drives, and other biotechnologies for conservation purposes are being considered, researched, and developed. This paper introduces the methods, applications, environmental risks, and social challenges of ‘conservationist synthetic biology’; reviews existing governance, with an emphasis on international instruments, institutions, and processes; and offers observations of the politics of developing further governance. The most important multilateral environmental agreement is the Convention on Biological Diversity. Governance of such conservationist synthetic biology is vital but gaps remain. The further development of governance is a political process, and conservationist synthetic biology has a political landscape that is atypical for emerging technologies.
Assessment of a Novel Adult Mass-Rearing Cage for Aedes albopictus (Skuse) and Anopheles arabiensis (Patton).
15562H. Maïga, W. Mamai, N. S. Bimbilé Somda, T. Wallner, B. S. Poda, G. Salvador-Herranz, R. Argiles-Herrero, H. Yamada and J. Bouyer, Insects, 11:801. 2020-11-13 15:09:03.
Successful implementation of the sterile insect technique (SIT) against Aedes albopictus and Anopheles arabiensis relies on a continuous supply of sterile males. To meet this requirement, optimization of the mass-rearing techniques is needed. This study, therefore, aims to assess a new mass-rearing cage (MRC) in terms of egg production efficiency and egg hatch rate (quality). In addition, adult survival was evaluated based on a cage adult-index for Ae. albopictus. Moreover, the cage’s suitability for use in mass An. arabiensis egg production was compared to that of the FAO/IAEA Anopheles reference cage. In Ae. albopictus rearing, the new MRC produced 1,112,110 eggs per cage following six blood meals, with minimum loss of eggs in the egging water. Furthermore, the adult index gave a good proxy of daily mortality rates in Ae. albopictus. In An. arabiensis rearing, about 130,000 eggs per egg batch were collected both from the new and the reference MRC. These findings suggest that the new MRC prototype is efficient in terms of egg production and can be used for mass-rearing in SIT programs targeting Ae. albopictus as well as An. arabiensis. The adult index was also positively validated for the detection of unusual mortality rates in Ae. albopictus mass-rearing facilities. Overall, the new MRC has shown several advantages; however, further improvements are necessary to minimize escapes during the egg collection processes
Gene drive blocks malaria transmission in mosquitoes
15035labonline, labonline, 2020-11-09 15:46:59.
Employing a strategy known as ‘population modification’, which involves using a CRISPR-Cas9 gene drive system to introduce genes preventing parasite transmission into mosquito chromosomes, University of California (UC) researchers have made a major advance in the use of genetic technologies to control the transmission of malaria parasites. Their work has been published in the journal Nature Communications.
Expert advises farmers to adopt gene drive-based pest control technology
15029S. Thompson, naija247news, 2020-11-09 15:36:25.
Dr Rose Gidado, County Coordinator, Open Forum on Agricultural Biotechnology(OFAB), has advised farmers to adopt the gene drive-based pest control technology. Gidado, also Deputy Director, National Biotechnology Development Agency (NABDA), said the adoption would significantly help to restore Nigeria’s food crop industry. According to her, Nigerian agricultural system is dominated by the application of synthetic pesticides which have resulted in environmental pollution. Gidado said that it had contributed greatly to climate change, with lethal consequences like increased pest attack, decreased crop yield and extreme heat stress in plants. The scientist said the application of gene drive in Nigeria’s agricultural system, would help greatly in the control of deadly insect pests which cause damages to crops and reduction in food production.
Advances in genetic engineering test democracy’s capacity for good decision-making
15027N. Kofler and R. Taitingfong, Boston Globe, 2020-11-09 15:31:50.
New advances in genetic engineering and their application for environmental conservation and public health are further testing our democracy’s capacity for good decision-making. With minimal public input, the Environmental Protection Agency recently approved the release of genetically modified mosquitoes in Florida and Texas. An application for the planting of GM American Chestnut trees, engineered to reproduce and spread in the wild, is currently under review by the US Department of Agriculture. And even more complex and powerful genetic technologies intended for environmental release are in the research pipeline.
Fighting Mosquito With GMO Mosquito: The Battle Brewing in the Florida Keys
15005S. MacLaughlin, NBC 6 South Florida, 2020-11-06 15:32:04.
Scientists are a few months into an experiment to stop the invasive Aedes aegypti mosquito. Their weapon of choice? A genetically modified mosquito. But some environment advocates question the strategy. This year, the Florida Keys had an outbreak of Dengue fever, which was the first time that had happened in 10 years. It gives new urgency to the controversial effort to get rid of the Aedes aegypti, which has become harder to fight.
Florida will release 750 million genetically modified mosquitoes
14998S. McGlaun, Slash Gear, 2020-11-05 15:14:43.
Local officials in Florida have announced that they have approved 750 million genetically modified mosquitoes to be released into the environment to reduce local populations of the bloodsucking creatures. The goal of releasing genetically modified mosquitoes is to help reduce the number of mosquitoes carrying diseases like dengue or the Zika virus. Approval to release the bugs came after environmental groups warned of unintended consequences.
A gene-drive rescue system for the modification of malaria mosquito populations
14901A. Adolfi, Nature Research Bioengineering Community, 2020-11-03 18:48:29.
Mosquito populations can now be reliably modified using 1) antimalarial molecules that block parasite development and 2) a CRISPR-based gene drive system that mediates their rapid spreading across the vector population.
UC researchers pioneer more effective method of blocking malaria transmission in mosquitoes
14898UCI, UCI News, 2020-11-03 14:11:01.
University of California, Irvine postdoctoral researcher Adriana Adolfi, in collaboration with colleagues at UCI, UC Berkeley and UC San Diego, followed up on the group’s pioneering effort to develop CRISPR-based gene drive systems for making mosquito vectors resistant to transmitting malaria parasites by increasing gene drive effectiveness in female mosquito progeny.The second-generation gene drive system described in this paper can be applied to any of the several thousand genes that are essential for insects to survive or reproduce,” said UC San Diego Distinguished Professor Ethan Bier, a co-author of the study and science director at the Tata Institute for Genetics and Society. “While it was developed in fruit flies, this system is readily transportable to a broad selection of insect species that serve as vectors for devastating disorders such as Chagas disease, sleeping disease, leishmaniasis and arboviral diseases.”
Genetic engineering of sex chromosomes for batch cultivation of non-transgenic, sex-sorted males
19246S. R. Das, M. Maselko, A. Upadhyay and M. J. Smanski, PloS Genetics, 16:11. 2020-11-02 22:13:55.
The field performance of Sterile Insect Technique (SIT) is improved by sex-sorting and releasing only sterile males. This can be accomplished by resource-intensive separation of males from females by morphology. Alternatively, sex-ratio biasing genetic constructs can be used to selectively remove one sex without the need for manual or automated sorting, but the resulting genetically engineered (GE) control agents would be subject to additional governmental regulation. Here we describe and demonstrate a genetic method for the batch production of non-GE males. This method could be applied to generate the heterogametic sex (XY, or WZ) in any organism with chromosomal sex determination. We observed up to 100% sex-selection with batch cultures of more than 10(3) individuals. Using a stringent transgene detection assay, we demonstrate the potential of mass production of transgene free males. Author summary In this manuscript, we describe and demonstrate in a model system a new genetic engineering approach for producing sex-sorted, non-transgenic batches of an organism with genetic sex determination. This approach could impact pest control programs using Sterile Insect Technique.
The Sterile Insect Technique: Success and Perspectives in the Neotropics
15185D. Perez-Staples, F. Diaz-Fleischer and P. Montoya, Neotropical Entomology, 14. 2020-10-28 15:12:56.
Here, we review SIT in the Neotropics and focus on particular recent successful cases of eradication of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), as well as effective programs used against the Mexican fruit fly Anastrepha ludens (Loew), the New World screwworm fly Cochliomyia hominivorax (Coquerel)), and the Cactus moth Cactoblastis cactorum (Berg). We examine when SIT does not work and innovations that have made SIT more efficient and also highlight complimentary techniques that can be used in conjunction. We address potential candidate species that could be controlled through SIT, for example Philornis downsi Dodge & Aitken. Finally, we consider the impact of climate change in the context of the use of the SIT against these pests. Given the recent dramatic decline in insect biodiversity, investing in environmentally friendly means of pest control should be a priority. We conclude that SIT should be promoted in the region, and leadership and political will is needed for continued success of SIT in the Neotropics.
Researchers help complete world first wasp genome project
14798Staff, The National Tribune, 2020-10-21 15:12:01.
In a world first, New Zealand researchers have sequenced the genome of three wasps, two of which are invasive wasps in New Zealand, paving the way for new methods of control for these significant pests.
Researchers complete world first wasp genome project
14796University of Otago, Phys Org, 2020-10-21 15:07:20.
In a world first, New Zealand researchers have sequenced the genome of three wasps, two of which are invasive wasps in New Zealand, paving the way for new methods of control for these significant pests.
Cellular mechanisms regulating synthetic sex ratio distortion in the Anopheles gambiae germline
14790R. E. Haghighat-Khah, A. Sharma, M. R. Wunderlich, G. Morselli, L. A. Marston, C. Bamikole, A. Hall, N. Kranjc, C. Taxiarchi, I. Sharakhov and R. Galizi, Pathogens and Global Health, 114:370-378. 2020-10-20 20:24:19.
Meiotic cleavage of rDNA repeats, located in the sex chromosomes of A. gambiae SD males, affects the competitiveness of mature sperm to fertilize the female oocyte.
Vector-Focused Approaches to Curb Malaria Transmission in the Brazilian Amazon: An Overview of Current and Future Challenges and Strategies
15960E. M. Rocha, R. D. Katak, J. C. de Oliveira, M. D. Araujo, B. C. Carlos, R. Galizi, F. Tripet, O. Marinotti and J. A. Souza, Tropical Medicine and Infectious Disease, 5. 2020-10-20 18:16:39.
Here we present an overview on both conventional and novel promising vector-focused tools to curb malaria transmission in the Brazilian Amazon. If well designed and employed, vector-based approaches may improve the implementation of malaria-control programs, particularly in remote or difficult-to-access areas and in regions where existing interventions have been unable to eliminate disease transmission. However, much effort still has to be put into research expanding the knowledge of neotropical malaria vectors to set the steppingstones for the optimization of conventional and development of innovative vector-control tools.
WHO Releases a Position Statement on Genetically Modified Mosquitoes for the Control of Vector-Borne Diseases
14793E. R. Fletcher, Health Policy Watch, 2020-10-19 14:56:43.
WHO announced their support for the continued investigation into genetically modified mosquitoes as an alternative to existing interventions to reduce or prevent vector-borne diseases.
Genetic engineering and bacterial pathogenesis against the vectorial capacity of mosquitoes
14721M. Qasim, H. M. Xiao, K. He, M. A. A. Omar, F. L. Liu, S. Ahmed and F. Li, Microbial Pathogenesis, 147:8. 2020-10-16 18:16:01.
Here we aimed to focus on the role of bacterial pathogenesis and molecular tactics for the management of mosquitoes and their vectorial capacity.
FKMCD-OXITEC Mosquito Project
14718FKMCD and OXITEC, Website, 2020-10-16 18:11:37.
The Florida Keys Mosquito Control District (FKMCD) Board of Commissioners approved the FKMCD-Oxitec Investigational Agreement for the release of Oxitec’s Aedes aegypti mosquitoes. This project will be overseen by FKMCD, the EPA and the Florida Department of Agriculture and Consumer Services (FDACS). Independent evaluation of the project will be provided by the U.S. CDC, University of Florida, Monroe County Department of Health, and local leaders, forming a broad and diverse coalition to support this effort.
Ethics and vector-borne diseases
14904Geneva: World Health Organization, WHO Guidance, 2020-10-14 18:57:10.
The guidance was developed by an international group of experts in vector control, infectious disease ethics, maternal and child health, ecology and climate change, research and vaccine development, and public health communication. It examines a broad range of ethical considerations related to VBD prevention and control, including the social and environmental determinants of health; vector control methods, including emerging technologies; screening, surveillance and research; vaccine campaigns; and mass drug administration.
Driven to Exterminate
14724Z. Moloo and J. Thomas, etc group, 2020-10-14 18:16:08.
Gates’s ‘let’s deploy it’ response may not seem out of character, but it was an unusually gung ho response given how risky the technology is widely acknowledged to be.
Florida to Release 750 Million GMO Mosquitoes in 2021
14703Seeker, Seeker, 2020-10-13 18:11:21.
The U.S. EPA gave the green light to release millions of genetically modified mosquitoes in the Florida Keys in 2021 — here’s what we know.
Evaluation of genetically modified mosquitoes for the control of vector-borne diseases
14661Global Malaria Programme, WHO - Position Statement, 2020-10-13 15:58:38.
In the spirit of fostering innovation, WHO takes the position that all potentially beneficial new technologies, including GMMs, should be investigated to determine whether they could be useful in the continued fight against diseases of public health concern. Such research should be conducted in steps and be supported by clear governance mechanisms to evaluate the health, environmental and ecological implications
Towards rangatiratanga in pest management? Maori perspectives and frameworks on novel biotechnologies in conservation
14653S. Palmer, O. R. Mercier and A. King-Hunt, Pacific Conservation Biology, 11. 2020-10-09 13:58:04.
We gathered Maori perspectives on novel biotechnological controls for pest wasps through three distinct studies. Study participants included tertiary students, businesses, and spiritual or religiously affiliated groups. All participants drew from their identities as Maori people to help identify their position on these issues.
Yes, Irradiated Sterile Male Mosquitoes Can Be Sexually Competitive!
14645J. Bouyer and M. J. B. Vreysen, Trends in Parasitology, 2020-10-06 13:28:30.
Here, we argue that a reduction in quality of the produced sterile male insects is mostly related to the mass-rearing, handling, marking, and release processes, rather than radiation per se.
Standardizing the definition of gene drive
319582020-10-01 13:25:21.
Do Africans Want Genetically Modified Mosquitoes?
14591U. Effiong, The Pursuit, 2020-09-30 13:38:38.
The recent publication by fellow Nigerian scientists—Patricia Okorie and colleagues—originally drew my attention to the issue of GMMs.
You should be excited that scientists are releasing 750 million genetically modified mosquitoes this year
14568L. Westreich, Massive Science, 2020-09-27 19:27:28.
GM mosquitoes are successful in reducing mosquito populations, and reducing disease spread
The Con Job at Mosquito Control Board
14571E. Russo and B. Wray, keysnews.com, 2020-09-26 19:32:07.
Shouldn’t there be a consensus among scholars, scientists, experts and the public that this new technology is safe?
Can a Genetically Modified Bug Combat a Global Farm Plague?
14470E. Nitler, Wired, 2020-09-24 17:24:48.
Executives from the US-owned, but UK-based, firm Oxitec and its multinational partner Bayer announced today that they have developed a fall armyworm that has a self-limiting gene introduced into the male of the species.
Dynamics of Wild and Sterile Mosquito Population Models with Delayed Releasing
14817L. M. Cai, International Journal of Bifurcation and Chaos, 30:15. 2020-09-15 17:16:03.
We extend the previous ODE models to the delayed releasing models in two different ways of releasing sterile mosquitos, where both constant and exponentially distributed delays are considered, respectively. By applying the theory and methods of delay differential equations, the effect of time delays on the stability of equilibria in the system is rigorously analyzed.
The Evolving Arsenal Against Mosquito-Born Diseases
14369J. Smith, Labiotech.eu, 2020-09-10 16:01:02.
As the global climate continues to warm, disease-spreading mosquitoes such as Aedes aegypti are expected to establish themselves in the US and Europe.
Engineering speciation events in insects may be used to control harmful pests
14328University of Minnesota, Phys Org, 2020-09-08 17:55:45.
A team of scientists led by Mike Smanski, Ph.D., in the College of Biological Sciences (CBS) has generated speciation events in fruit flies so that engineered strains can reproduce normally with each other, but mating with unmodified flies results in non-viable offspring.
Prospects and Pitfalls: Next-Generation Tools to Control Mosquito-Transmitted Disease
14366E. P. Caragata, S. Dong, Y. Dong, M. L. Simões, C. V. Tikhe and G. Dimopoulos, Annual Review of Microbiology, 74:455-475. 2020-09-08 15:57:19.
A diverse array of next-generation tools has been designed to eliminate mosquito populations or to replace them with mosquitoes that are less capable of transmitting key pathogens.
How to fight the deadly dengue virus? Make your own mosquitoes
14320J. Emont, Wall Street Journal, 2020-09-07 15:13:25.
When the bacteria-laden male mosquitoes are released into the open and mate with naturally-born females, the resultant eggs won’t hatch.
GMOs make war on mosquitoes
14323Staff, Kenosha News, 2020-09-05 15:13:38.
Given that recent record, we were a bit surprised to read that there was a ruckus over genetically modified mosquitoes going on in the Florida Keys.
Why Genetically Modified Mosquitoes Won’t Come to Texas Anytime Soon
14317C. Adams, RA News, 2020-09-04 15:03:04.
Talks about releasing genetically modified mosquitoes in Houston began in 2018 between Harris County and Oxitec, a United Kingdom-based company that produces sustainable technologies or transgenic methodologies to stem the impact of disease-spreading insects. Talk also began about a similar action in Monroe County, Fla.
Non-GMO approach reduces cases of mosquito-borne dengue by 77%
14239GM Watch, GM Watch, 2020-08-31 13:55:39.
A randomized field trial found that mosquitoes infected with a natural bacterium called Wolbachia reduced cases of dengue by an "extraordinary" 77%.
An accident waiting to happen: Tech company to release 750 MILLION GMO mosquitoes in Florida to fight dengue fever
14232Z. Sky, NEWSTARGET, 2020-08-30 20:31:13.
Oxitec plans to release 750 million OX5034s into the Florida Keys, something that sounds like the beginning of a doomed science-fiction movie. But the most shocking thing here is the fact that Oxitec received the EPA’s approval in May.
Genetically-modified mosquito plan offers hope for Keys, world
14256P. Goodman, keynews.com, 2020-08-29 14:25:12.
The Florida Keys Mosquito Control District Board of Commissioners voted 4-to-1 to approve a trial using Oxitec’s second-generation genetically modified mosquitoes. I
Bacteria-Laced Mosquitoes Limit Spread of Dengue
14244A. Heidt, The Scientist, 2020-08-29 14:05:32.
Researchers have infected Aedes aegypti mosquitoes—the species responsible for passing on many diseases—with bacteria called Wolbachia with the intent of reducing the insects’ ability to pass on dengue to people.
The good mosquito versus the bad
14240D. Datta, Business Standard, 2020-08-29 14:01:00.
Starting 2021, around 750 million genetically modified (GM) Aedes Aegypti mosquitoes will be released in batches into the Florida Keys.
Gene Drive Dynamics in Natural Populations: The Importance of Density Dependence, Space, and Sex
15277S. Dhole, A. L. Lloyd and F. Gould, Annual Review of Ecology, Evolution, and Systematics, 51:505-531. 2020-08-28 21:09:09.
The spread of synthetic gene drives is often discussed in the context of panmictic populations connected by gene flow and described with simple deterministic models. Under such assumptions, an entire species could be altered by releasing a single individual carrying an invasive gene drive, such as a standard homing drive. While this remains a theoretical possibility, gene drive spread in natural populations is more complex and merits a more realistic assessment. The fate of any gene drive released in a population would be inextricably linked to the population’s ecology. Given the uncertainty often involved in ecological assessment of natural populations, understanding the sensitivity of gene drive spread to important ecological factors is critical. Here we review how different forms of density dependence, spatial heterogeneity, and mating behaviors can impact the spread of self-sustaining gene drives. We highlight specific aspects of gene drive dynamics and the target populations that need further research.
Florida Will Release 750 Genetically Modified Mosquitoes to Stop Disease Spread
14177A. Fahmy, verywell health, 2020-08-28 14:36:32.
The hope is to prevent the spread of Dengue fever, a painful virus acquired only by mosquito bite which made a reappearance in the Florida Keys in 2009.
Scientists infect mosquitoes with bacteria to stop the transmission of dengue fever in Indonesia, dropping infection rates by 77 percent
14250D. Avery, Daily Mail, 2020-08-28 14:15:52.
The team found that dengue infections were 77 percent lower in treated neighborhoods, compared to areas not exposed to the infected insects.
The mosquito strategy that could eliminate dengue
14170E. Callaway, Nature, 2020-08-27 14:19:52.
The study, conducted in an Indonesia city, showed that releasing mosquitoes modified to carry a bacterium called Wolbachia, which stops the insects from transmitting some viruses, led to a steep drop in cases of dengue fever.
Researchers Find New Approach To Control Dengue, Zika By Genetically Modifying Mosquitoes
14247N. Sharma, R. Republicworld.com, 2020-08-27 14:11:56.
A new study carried out in Indonesia has shown that dengue infection rates decreased in regions where the genetically modified mosquitoes were introduced.
Australian research takes aim at dengue, another killer virus
14226E. Connors, Finanacial Review, 2020-08-26 20:22:39.
Australian researchers have teamed up with Indonesian philanthropists to strike a blow against dengue fever, the deadly disease that was a growing scourge in south-east Asia and South America long before COVID-19.
Australian scientists slash dengue fever in Indonesia by infecting mosquitoes with bacteria
14224A. Barker, ABC News, 2020-08-26 20:17:56.
Australian scientists may have found the secret to eradicating dengue fever, with a lengthy trial in Indonesia drastically reducing the incidence of the mosquito-borne virus.
Deep dive: Florida’s GM mosquito experiment aims to rewrite rules of vector-borne diseases
14084S. Kannan, India Today, 2020-08-26 14:33:36.
A pathbreaking bioengineering experiment on mosquito populations that could have massive implications for tropical malaria-affected countries like India has got underway in Florida, US.
Fighting mosquito-borne diseases… with mosquitoes
14156N. Gubert and A. Baubeau, Phys Org, 2020-08-26 13:13:41.
For decades, researchers have scratched their heads over how to combat deadly mosquito-borne diseases such as dengue fever.
Bug board OKs release of genetically modified mosquitoes
14151T. O'Hara, keynews.com, 2020-08-26 13:08:07.
After nearly 10 years of debate, the Florida Keys Mosquito Control District board has approved an agreement with biotech company Oxitec to conduct a test release of genetically modified mosquitoes in Monroe County as part of a mosquito limiting or eradication plan.
Genetically modified mosquitoes to be released in the Florida Keys to combat dengue, zika, and yellow fever.
14148Yucatan Times, Yucatan Times, 2020-08-26 13:04:27.
The Florida Keys will be the scene of the first test in the United States with genetically modified Aedes aegypti mosquitoes, an alternative to insecticides and larvicides to end the transmission of diseases such as dengue, zika and yellow fever that has always been surrounded by controversy.
Transgenic moths released to end one of the worst pests on the planet
14099B. Mandalia, Pledge Times, 2020-08-25 14:49:50.
Today the results of the first open field experiment with another of the creations of this biotechnology company are published. It is a variant of the moth Plutella xylostella which is one of the worst agricultural pests in the world.
750 million genetically modified mosquitoes soon released in the wild!
14093explica, explica, 2020-08-25 14:42:52.
Rather frightening mosquitoes will be released on an archipelago in Florida. The goal? Reduce the population of their more dangerous congeners who can transmit certain diseases.
US to Use Genetically Modified Mosquitoes to Fight Dengue Fever
14090H. Badr, Asharq Al-Awsat, 2020-08-25 14:39:32.
After a decade of discussions, officials in Florida have voted to allow the first test in the United States of free-flying, genetically modified mosquitoes that kill any female offspring, as a way to fight the pests and the diseases they spread.
Florida Keys to Use Genetically Modified Mosquitoes to Fight Disease
14087B. Lynn, Voice of America, 2020-08-25 14:33:57.
Officials in the Florida Keys plan to release genetically modified mosquitoes next year in an effort to fight insect-borne diseases.
Florida Approves Controversial Plan to Release 750 Million Genetically Modified Mosquitoes
14096D. Rakshit, Swaddle, 2020-08-24 14:46:17.
Authorities in Florida have approved a pilot project that will release 750 million genetically modified mosquitoes locally, in a bid to reduce the populations of mosquitoes that cause that cause dengue, Zika, chikungunya, and yellow fever
Mutant bugs released to fight disease
14081The Day, The Day, 2020-08-24 14:20:37.
Authorities have approved the scheme in Florida but environmental groups are furious, calling it a “Jurassic Park experiment” that will unleash a “mutant bug” into the ecosystem.
More than 750 million GMO mosquitoes to be released over Florida Keys – what could go wrong?
14145E. Huff, Natural News, 2020-08-24 12:59:20.
The Florida Keys Mosquito Control District (FKMCD) has given Oxitec, a corporation we have reported on in the past, permission to unleash some 750 million GMO mosquitos in Monroe County, Florida, over the next two years.
Florida to release genetically modified mosquitoes to prevent diseases like Zika
14009The West News, The West News, 2020-08-23 17:50:16.
Local authorities on Tuesday gave final approval to release 750 million genetically modified mosquitoes in the Florida Keys over a two-year period, starting in 2021.
Genetically modified mosquitoes have been OK’d for a first U.S. test flight
14003S. Milius, ScienceNews, 2020-08-22 17:44:31.
After a decade of fits and starts, officials in the Florida Keys have voted to allow the first test in the United States of free-flying, genetically modified mosquitoes as a way to fight the pests and the diseases they spread.
Florida Will Release Genetically Modified Mosquitoes to Fight Disease in the Keys
14000S. Harrell, Spectrum News, 2020-08-21 17:40:14.
Following lengthy federal and state procedures, the Florida Keys Mosquito Control District this week approved a plan to release more than 750 million genetically modified mosquitoes in the Keys region to combat an invasive, disease-carrying species of the insect.
Florida is releasing 750 million genetically modified mosquitoes into the world. Here’s why
13992H. Schriber, Deseret News, 2020-08-21 17:35:50.
Florida officials plan to release 750 million genetically modified mosquitoes into the Florida Keys over the next two years as a way to prevent diseases like the Zika virus. The project will begin in 2021. The Environment Protection Agency approved the idea in May. The project will test if one of these mosquitoes can work better than spraying insecticides to stop these insects from spreading potentially fatal viruses, according to CNN.
Genetically Modified Mosquitoes To Be Released In Florida Keys
13989A. Snow, The Daily Wire, 2020-08-21 17:33:00.
CNN reported that the genetically modified bugs, called OX5034, have been “altered to produce female offspring that die in the larval stage, well before hatching and growing large enough to bite and spread disease.” Since it’s the female of the species that bite, they are the ones that carry diseases. Males, the outlet reported, eat nectar.
Release 750 Million Genetically Modified Mosquitoes Into the Wild, They Said
13986C. Delbert, Popular Mechanics, 2020-08-21 17:31:14.
Corporate scientists have received final approval from the Environmental Protection Agency (EPA) to release hundreds of millions of genetically altered mosquitoes into the Florida Keys. The goal? To begin reining in the mosquito population, which is only expected to increase as climate change continues to warm and flood the low-lying, tropical Keys. But some environmental groups object strongly to the move.
Florida releasing genetically modified mosquitoes to prevent diseases like Zika
13984N. Lanese, LiveScience, 2020-08-21 17:29:18.
Hundreds of millions of genetically modified mosquitoes will soon be released in the Florida Keys island chain to wipe out local populations of disease-carrying mosquitoes, according to news reports.
750 Million GM Mosquitoes Will Be Released in the Florida Keys
13982L. Winter, The Scientist, 2020-08-21 17:27:30.
With the aim of reducing rates of the mosquito-borne illnesses yellow fever and dengue, a pilot program will release 750 million genetically modified mosquitoes into the Florida Keys in 2021, thanks to approval by the barrier islands’ Mosquito Control District Board of Commissioners at a meeting on Tuesday (August 18)
Hundreds Of Millions Of Genetically Modified Mosquitoes Approved For Release In US
13996J. Vibes, Anonymous News, 2020-08-20 17:37:24.
A Biotech company called Oxitec has received permission from the government to release hundreds of millions of genetically modified male mosquitoes in the Florida Keys.
Why Hundreds of Millions of Genetically Engineered Mosquitoes Will Soon Be Released in Florida
13979K. Gander, Newsweek, 2020-08-20 17:22:07.
Hundreds of millions of genetically engineered mosquitoes will soon be released in Florida, in a first for the U.S. On Tuesday, the Florida Keys Mosquito Control District (FKMCD) approved plans to release the insects, who do not bite, as part of a pilot project launching next yea
Florida to release genetically modified mosquitoes, detractors blast ‘Jurassic Park’ experiment
13969D. Aaro, Fox News, 2020-08-20 15:49:28.
Local authorities on Tuesday gave final approval to release 750 million genetically modified mosquitoes in the Florida Keys over a two-year period, starting in 2021, with the hope of preventing diseases such as the Zika virus but has faced blowback and comparisons to a Steven Spielberg thriller.
750 million genetically modified mosquitoes to be released across Florida Keys
13966A. Zahid, Sky News, 2020-08-20 15:47:05.
Authorities have approved plans for genetically modified mosquitoes to be released across the Florida Keys from next year. British-based firm Oxitec has designed the project to test whether the altered mosquitoes are a viable alternative to pesticides to control and prevent the spread of diseases, including Zika and dengue.
750 million GM mosquitos set for release in Florida Keys.
13961Editorial Staff, E&T, 2020-08-20 15:43:13.
Local authorities have approved proposals to release hundreds of millions of genetically modified (GM) modified mosquitos in Florida, in an effort to control populations of diseases spread by the organism.
Florida Plans to Fix Its Mosquito Problem With 750 Million More Mosquitoes
13959D. Noor, Gizmodo, 2020-08-20 15:40:34.
Hundreds of millions of mosquitos will soon be released in Florida. On purpose. The mosquitoes are being released as a form of pest control, but they could wreak havoc on local ecosystems.
Florida mosquitoes: 750 million genetically modified insects to be released
13955BBC, BBC, 2020-08-20 15:37:01.
Local officials in Florida have approved the release of 750 million mosquitoes that have been genetically modified to reduce local populations. The aim is to reduce the number of mosquitoes that carry diseases like dengue or the Zika virus.
Florida OKs release of genetically modified mosquitoes in Keys to slow insect disease spread
13952S. Mann, Just the News, 2020-08-20 15:34:23.
Florida officials are authorizing a biotech company to release hundreds of millions of genetically-modified male mosquitoes into the Florida Keys to reduce future mosquito populations that spread diseases including yellow fever and malaria.
Florida Keys to release modified mosqutioes to fight illness
13949C. Anderson, Associated Press, 2020-08-20 15:30:15.
Sometime next year, genetically modified mosquitoes will be released in the Florida Keys in an effort to combat persistent insect-borne diseases such as Dengue fever and the Zika virus. The plan approved this week by the Florida Keys Mosquito Control District calls for a pilot project in 2021 involving the striped-legged Aedes aegypti mosquito, which is not native to Florida.
Florida to Release Millions of Genetically Modified Mosquitoes Against Local Residents’ Wishes
13946N. Rice, People, 2020-08-20 15:27:38.
A plan to release over 750 million genetically modified mosquitoes in the Florida Keys has received final approval. According to CNN, on Tuesday, local authorities approved a plan to release the genetically modified mosquitoes in the Sunshine State's string of islands, with the hope of preventing a string of diseases that the insects can carry.
Plan to Release 750M GMO Mosquitoes Gets Go Ahead
13944R. Quinn, newser, 2020-08-20 15:23:41.
The plan to release the genetically modified Aedes aegypti mosquitoes received final approval from local authorities Tuesday, causing an outcry from groups opposed to what they call a "Jurassic Park experiment," CNN reports.
‘A Jurassic Park Experiment’: Watchdog Groups Denounce Decision to Release Genetically Modified Mosquitoes in Florida
13975L. Newcomb, Common Dreams, 2020-08-19 15:54:09.
Food safety and environmental groups Wednesday condemned a decision by officials in Florida to approve the release of 750 million genetically modified mosquitoes, a pilot project aimed at reducing the spread of mosquito-borne diseases.
Florida Keys to release 750M genetically modified mosquitoes
13972D. Haynes, UPI, 2020-08-19 15:51:58.
Local authorities in the Florida Keys gave their approval Wednesday to a plan to release genetically modified mosquitoes to prevent the spread of dengue fever and other diseases. The Monroe County Mosquito Control District signed off on the project, which would release about 750 million mosquitoes engineered to produce dead offspring.
FKMCD Board Approves Oxitec Pilot
14929C. Huff, FKMCD in the News, 2020-08-19 15:48:10.
The Florida Keys Mosquito Control District’s (FKMCD) five member board has APPROVED a proposal by Oxitec to utilize non-biting male, genetically modified mosquitoes as part of a trial to determine their effectiveness in controlling the wild population of Aedes aegypti, the mosquito which is responsible for spreading diseases such as dengue fever. FKMCD and Oxitec have both said that the pilot project will not take place until 2021. The FKMCD board’s four to one vote in FAVOR comes after Federal and State approvals of an ‘Experimental Use Permit’ issued earlier this summer by the Environmental Protection Agency and The Florida Department of Agriculture and Consumer Services. F
To combat disease-spreading mosquitoes in the Keys, leaders vote to unleash lab bugs
13964D. Goodhue, Miami Herald, 2020-08-19 15:44:52.
Florida Keys officials have voted to allow the experimental release of millions of genetically modified mosquitoes into a yet-to-be-decided area of the island chain.
Genetically Modified Mosquitoes Cleared for Florida Keys Release
13901J. Kay, Bloomber Law, 2020-08-18 13:36:35.
Genetically engineered mosquitoes will be released in the Florida Keys in 2021 to try to reduce the population of a biting insect pest that spreads Zika, dengue fever, and yellow fever, local officials said Tuesday.
Researchers’ Plan To Release Genetically Engineered American Chestnut Trees in Forests Will Set Dangerous Precedents If Approved
13890Global Justice Ecology Project, Common Dreams, 2020-08-18 13:20:50.
Researchers are working with the United States Department of Agriculture (USDA) to finalize a petition requesting the unprecedented approval of a genetically engineered (GE or genetically modified) tree designed to be planted in our forests and spread freely in the wild. Once the internal petition process is complete, the USDA will release it for public comment. This is expected to occur at any time.
Keys Mosquito Control Board Approves First U.S. Trial Of Genetically Modified Mosquitoes
13887N. Klingener, WLRN, 2020-08-18 13:16:55.
The Florida Keys Mosquito Control Board approved a trial Tuesday of genetically modified mosquitoes on the island chain. This would be the first U.S. trial of the genetically modified Aedes aegypti mosquito, which can transmit diseases like Zika and dengue.
Modeling the suppression dynamics of Aedes mosquitoes with mating inhomogeneity
13847M. Huang and L. Hu, Journal of Biological Dynamics, 14:656-678. 2020-08-04 13:51:41.
In this work, we introduce a delay differential equation model with mating inhomogeneity to discuss mosquito population suppression based on Wolbachia. Our analyses show that the wild mosquitoes could be eliminated if either the adult mortality rate exceeds the threshold δ∗A or the release amount exceeds the threshold r∗ uniformly. Our simulations suggest that the releasing should be started at least 5 weeks before the peak dengue season, taking into account both the release amount and the suppression speed.
Genomic analyses of a livestock pest, the New World screwworm, find potential targets for genetic control programs
13618M. J. Scott, J. B. Benoit, R. J. Davis, S. T. Bailey, V. Varga, E. O. Martinson, P. V. Hickner, Z. Syed, G. A. Cardoso, T. T. Torres, M. T. Weirauch, E. H. Scholl, A. M. Phillippy, A. Sagel, M. Vasquez, G. Quintero and S. R. Skoda, Nature Communications, 3:424. 2020-08-04 12:56:38.
We identify and analyze the expression of genes that are likely important for host-seeking behavior (chemosensory), development of larvae in open wounds in warm-blooded animals (heat shock protein, immune response) and for building transgenic strains for genetic control programs including gene drive (sex determination, germline). This study will underpin future experiments aimed at understanding the parasitic lifestyle of the screwworm fly and greatly facilitate future development of strains for efficient systems for genetic control of screwworm.
Exploring gene drive’s role in fight against malaria
13536J. Conrow, Genetic Literacy Project, 2020-08-02 17:02:28.
J. Conrow (2020) Genetic Literacy Project. An international initiative has formed to ensure that gene drive technology gets a chance to prove its mettle in the quest to control malaria.
Efficient population modification gene-drive rescue system in the malaria mosquito Anopheles stephensi
13593A. Adolfi, V. M. Gantz, N. Jasinskiene, H.-F. Lee, K. Hwang, E. A. Bulger, A. Ramaiah, J. B. Bennett, G. Terradas, J. J. Emerson, J. M. Marshall, E. Bier and A. A. James, bioRxiv, 2020.08.02.233056. 2020-08-02 12:59:26.
We developed the first recoded gene-drive rescue system for population modification in the malaria vector, Anopheles stephensi, that relieves the load in females caused by integration of the drive into the kynurenine hydroxylase gene by rescuing its function. Non-functional resistant alleles are eliminated via a dominantly-acting maternal effect combined with slower-acting standard negative selection, and a functional resistant allele does not prevent drive invasion.
Biotechnologies in pest wasp control: taking the sting out of pest management for Māori businesses?
14710S. Palmer and O. R. Mercier, New Genetics and Society, 2020-07-31 19:13:18.
A Maori-centered mixed-method study gauged the perceptions of eight Maori businesses about the potential use of five specific new biotechnological controls in pest management.
Nix alone is sufficient to convert female Aedes aegypti into fertile males and myo-sex is needed for male flight
13780A. Aryan, M. A. E. Anderson, J. K. Biedler, Y. M. Qi, J. M. Overcash, A. N. Naumenko, M. V. Sharakhova, C. H. Mao, Z. N. Adelman and Z. J. Tu, Proceedings of the National Academy of Sciences of the United States of America, 117:17702-17709. 2020-07-28 13:17:04.
Here, we report the generation of multiple transgenic lines that express Nix under the control of its own promoter. Genetic and molecular analyses of these lines provided insights unattainable from previous transient experiments. We show that the Nix transgene alone, in the absence of the M-locus, was sufficient to convert females into males with all male-specific sexually dimorphic features and male-like gene expression.
Why are scientists creating genetically modified mosquitoes?
13503The Week Staff, The Week, 2020-07-27 11:35:19.
The Week Staff. The Week (2020). Scientists plan to release altered mosquitoes designed to sabotage the species' ability to reproduce. Is this safe? Here's everything you need to know:
Tackling Dengue fever by turning female mosquitoes into males
13482T. Sandle, DIGTAL JOURNAL, 2020-07-22 21:00:41.
T. Sandle (2020). DIGTAL JOURNAL Genetic engineering appears to be the key for delivering mosquito control, according to new research. Scientists have successfully converted female mosquitoes into non-biting males.
Florida Keys delays vote on release of 750 million genetically engineered mosquitoes after public outcry
13506D. Dukule, Friends of the Earth, 2020-07-22 12:41:45.
The Florida Keys Mosquito Control District (FKMCD) today delayed its vote on the proposed release of genetically engineered (GE) mosquitoes due to concerns over COVID-19. The decision to delay the vote follows public outcry and scientific dispute over the risks posed to public health and the environment by this experimental release. The approval would have permitted the British company Oxitec to release 750 million GE mosquitoes over a two-year period in Monroe County, Florida, starting as soon as this summer.
Release of genetically modified mosquitoes in the Florida Keys put on hold
13355D. Goodhue, Miami Herald, 2020-07-21 19:27:08.
Opponents of a plan to release millions of genetically modified mosquitoes in the Florida Keys landed a temporary win on Tuesday.
Researchers convert female mosquitoes to nonbiting males with implications for mosquito control
13194Virginia Tech, ScienceDaily, 2020-07-14 18:12:22.
Researchers convert female mosquitoes to nonbiting males with implications for mosquito control Virginia Tech researchers have proven that a single gene can convert female Aedes aegypti mosquitoes into fertile male mosquitoes and identified a gene needed for male mosquito flight
On Nonlinear Pest/Vector Control via the Sterile Insect Technique: Impact of Residual Fertility
14291M. S. Aronna and Y. Dumont, Bulletin of Mathematical Biology, 82:29. 2020-07-09 14:09:49.
We consider a minimalist model for the Sterile Insect Technique (SIT), assuming that residual fertility can occur in the sterile male population.
Beyone the buzz
13166C. Watson, The Journal Gazette, 2020-07-07 14:45:26.
Lately I have found I need to force myself to follow science stories about something besides the pandemic. A story I consider hopeful involves genetically modified mosquitoes; we are developing a new tool that can reduce disease and save lives. The goal is to dramatically reduce the mosquito population. Mosquitoes, by biting people and injecting some of their saliva, spread diseases such as yellow fever, dengue fever and malaria. Malaria kills about 600,000 people a year, mostly outside the U.S. The new tool being developed involves modifying the genes of male mosquitoes. The goal is to design a male mosquito that will behave typically, but whose female offspring die almost immediately.
GMO Mosquitoes to be launched in Florida
13162Administration, Editorials 360, 2020-07-01 14:38:18.
In June 2020, the Florida Division of Agriculture and Shopper Providers gave the go-ahead to a plan to launch thousands and thousands of genetically engineered mosquitoes within the Florida Keys this summer time to battle mosquito-borne diseases.1 The plan follows the EPA’s current granting of an experimental use allow (EUP) for the GMO (genetically modified organism) mosquitoes to allow them to be launched in Florida in 2020 and in Texas in 2021.2 The mosquitoes, engineered from the Aedes aegypti mosquito species,3 have been created by the U.S.-owned, Britain-based firm Oxitec, which originated as a spin-off firm from Oxford College and subsidiary of Intrexon.4 The corporate has additionally created genetically modified pink bollworm moths and GMO cabbage moths.
Who is afraid of genetically modified mosquitoes?
12738G. Odogwu, The PUNCH, 2020-06-25 13:27:54.
Genetically Modified Organisms have raised concerns in our clime, the same way they have in other countries of the world – where a clear line is drawn between the pro and the anti-GMO citizens. Nonetheless, this modern biotechnological technique is still at its infancy here. As of the moment, we can only boast of the development of the PBR cowpea as the only genetically modified food crop to be approved by the Nigerian government.
Mosquito district workshop focuses on Keys trials
12732S. Matthis, KEYSWEEKLY, 2020-06-25 13:21:52.
Now that the Oxitec “Friendly Mosquito” trials have been approved by the federal and state governments, it’s up to the Florida Keys Mosquito Control District to decide if, when and where to embrace the technology said to decrease the chances of mosquito-borne diseases such as dengue fever (there are two new cases in the Keys; see sidebar) and zika.
Genetically modified mosquitoes to be released in Florida and Texas
12735O. Ron, The Jerusalem Post, 2020-06-24 13:24:12.
A plan to release 750 million genetically modified mosquitoes in Florida and Texas has been approved, The Guardian reported. According to the plan, the Aedes aegypti mosquitoes will be released into the wild, as they contain a special protein that would kill female offspring, which are the ones who bite, and thus preventing the spread of such illnesses as dengue fever and Zika.
Before genetically modified mosquitoes are released, we need a better EPA
12720N. Kofler and J. Kuzma, The Boston Globe, 2020-06-22 13:07:55.
While the attention of the American public has rightfully been focused on the COVID-19 pandemic, its associated racial disparities, and broader issues of structural racism, the US government made a serious public health decision — one that could affect our health and our environment for generations to come. Last month, the US Environmental Protection Agency approved the release of genetically modified mosquitoes. Under a 2-year Experimental Use Permit, a company called Oxitec has been granted permission to release over 1 billion genetically modified mosquitoes across 6,600 acres in Florida and Texas.
Florida gives approval to the plan of releasing genetically modified mosquitoes.
12716V. Dalmia, The Andoverleader, 2020-06-20 21:01:10.
Mosquitoes have always been a huge problem for Florida residents. They are even more problematic in the Florida Key Region. It has even a dedicated mosquito department that is assigned with the task of controlling over 40 species of mosquitoes. But as technology progresses, we get new and newer methods to fight our problems. Gone are the days of pesticides.
Are Genetically Modified Mosquitoes Coming To Florida?
12726M. Taylor, Y100, 2020-06-19 13:13:35.
I'm not even going to lie, mosquitoes should be classified under domestic terrorism. The flying, biting bugs you can barely see wreak havoc on my life every single summer. I'm not sure if I'm allergic to them, but whenever I'm bit by them, that area of my skin swells up. It's the most annoying feeling in the world.
The Florida Keys are one step closer to getting genetically modified mosquitoes
12723D. Goodhue, Miami Herald, 2020-06-19 13:10:57.
An international biotech company is one step closer to being able to release genetically modified mosquitoes in the Florida Keys. The Florida Department of Agriculture and Consumer Services this week granted Oxitec an experimental use permit to release potentially millions of lab-made male Aedes aegypti mosquitoes throughout Monroe County. The goal is to wipe out the Keys population of the invasive bugs, which carry diseases like dengue fever, Zika and yellow fever. The Florida Department of Health reported a case of dengue fever in the Keys in March.
Genetically Modified Mosquitoes Approved For Insect Population Control In The U.S.
12705J. Blum, HUFFPOST, 2020-06-18 20:45:30.
Genetically modified mosquitoes with the ability to prevent other mosquitoes from spreading deadly diseases may be making their way to Florida backyards in the near future. British biotech group Oxitec announced on Tuesday that the company had won both federal and state approval to release its so-called “Friendly” mosquitoes in the U.S. on an experimental trial basis, expected to last until 2022, according to documents provided by the Environmental Protection Agency. The insects will first be released in Monroe County, Florida, and Oxitec has plans to also bring them tT Harris County, Texas.
Florida says ‘this is fine’ to release of genetically modified mosquitoes
12703J. K. Elliot, Global News, 2020-06-18 20:43:23.
That’s the question hanging over a recent decision by state regulators in Florida, which would allow the biotech company Oxitec to unleash hundreds of millions of genetically modified male mosquitoes in the Florida Keys. The lab-altered, patented insects are members of Aedes aegypti, the species of mosquito that spreads diseases such as yellow fever, malaria and chikungunya. However, they’ve been genetically altered to artificially reduce future mosquito populations.
Plan to Release GMO Mosquitoes Moves Ahead
12700A. Dier, newser, 2020-06-18 20:40:30.
A plan to set loose 750 million genetically modified mosquitoes in Florida and Texas will move forward despite concerns from environmentalists who liken it to a "Jurassic Park experiment." The non-biting male Aedes aegypti mosquitoes developed by British biotechnology company Oxitec contain a protein, passed to biting female offspring, that is designed to reduce the insect's chance of surviving into adulthood and therefore prevent the spread of mosquito-borne diseases including Zika and West Nile, reports the Guardian. The EPA has approved two trials, in which the mosquitoes are to be released in Florida's Monroe County this summer and in Texas' Harris County in 2021, though it's facing a lawsuit over its alleged failure to investigate the environmental impact, per the Hill. Facing similar complaints, Florida nonetheless approved its trial on Tuesday.
Genetically engineered mosquitoes get EPA approval for Florida release despite objections from environmental groups
12697S. LaMotte, CNN Health, 2020-06-18 20:37:52.
A genetically modified male mosquito named OX5034 has received both state and federal approval to be released into the Florida Keys now through 2022, against the objection of many local residents and a coalition of environmental advocacy groups. "The administration has used tax dollars and government resources for a Jurassic Park experiment, except without the island," said Jaydee Hanson, policy director at the International Center for Technology Assessment and Center for Food Safety, in a statement.
Florida Keys plans killer insect attack on disease-carrying mosquitoes
12693P. Brinkmann, UPI, 2020-06-18 20:33:39.
The Florida Keys is close to adding a new weapon to help control a mosquito-borne disease -- genetically modified mosquitoes that produce dead offspring. Outbreaks of dengue fever in the Keys in recent years prompted local authorities to consider the genetically modified bugs because the Aedes aegypti mosquito, which spreads that and other diseases, has shown resistance to pesticides.
Genetic breakdown of a Tet-off conditional lethality system for insect population control
13152Y. Zhao, M. F. Schetelig and A. M. Handler, Nature Communications, 11:3095. 2020-06-18 14:12:25.
Genetically modified conditional lethal strains have been created to improve the control of insect pest populations damaging to human health and agriculture. However, understanding the potential for the genetic breakdown of lethality systems by rare spontaneous mutations, or selection for inherent suppressors, is critical since field release studies are in progress. This knowledge gap was addressed in a Drosophila tetracycline-suppressible embryonic lethality system by analyzing the frequency and structure of primary-site spontaneous mutations and second-site suppressors resulting in heritable survivors from 1.2 million zygotes. Here we report that F1 survivors due to primary-site deletions and indels occur at a 5.8 × 10−6 frequency, while survival due to second-site maternal-effect suppressors occur at a ~10−5 frequency. Survivors due to inherent lethal effector suppressors could result in a resistant field population, and we suggest that this risk may be mitigated by the use of dual redundant, albeit functionally unrelated, lethality systems.
Plan to release genetically modified mosquitoes in Florida gets go-ahead
12695O. Milman, The Guardian, 2020-06-17 20:35:58.
A plan to release a horde of 750 million genetically modified mosqutioes in Florida and Texas is a step closer to fruition after a state regulator approved the idea, over the objections of many environmentalists.
EPA faces suit over plan to release genetically engineered mosquitoes
12457R. Frazin, The Hill, 2020-06-15 20:36:28.
The Environmental Protection Agency (EPA) is facing a lawsuit over its approval of a plan to release genetically modified mosquitoes in Florida and Texas
Fact check: Genetically modified mosquitoes are cleared for release in the US
12443A. Staver, USA Today, 2020-06-13 20:24:44.
The Environmental Protection Agency approved an experimental use permit May 1 that allows Oxitec to release genetically modified mosquitoes in the Florida Keys and Harris County, Texas, where Houston is located.
Gene Drive: Can this be the Future of Agricultural Pest Management?
13156P. Mondal, U. Mohapatra and M. Ganguly, International Journal of Current Microbiology and Applied Sciences, 9. 2020-06-10 14:25:16.
A world free of hunger may be possible when the agricultural production exceeds the global demand for the food. In the era of increasing population, the need for increased food production can be attainable by managing the destructive pests of the agricultural and horticultural crops. The detrimental effects of the pesticides and the attitudes of society towards transgenic crops indicate the researchers to catch out Gene Drive as the substitute method for former methods of crop pest management. In this context, the present narration describes how the self-sustaining CRISPR-based gene drive technology will be the leading technique in the near future for agriculture pest management.
Scientists hope to release genetically-modified mosquitoes
12437Fox 13, Fox 13, 2020-06-09 20:18:09.
Apparently, scientists are interested in releasing genetically-modified mosquitoes in Florida in order to help battle the spread of certain diseases.
Scientist fight plant to release gene-hacked mosquitoes in TX, FL.
12429D. Robitzski, Futurism, 2020-06-09 20:11:41.
Over the next two years, the biotech company Oxitec plans to release millions of genetically modified mosquitoes in Florida and Texas in an attempt to stop the spread of diseases like dengue and Zika. The U.S. Environmental Protection Agency (EPA) has already approved the plan — but a group of biologists, ecologists, bioethicists, and sustainability researchers writes in an article for The Conversation that they’re concerned about the lack of oversight for the effort to effectively hack the ecosystem.
Company Receives Permit To Release Swarm Of Genetically Modified Mosquitoes In Florida
12446I. Monzon, International Business Times, 2020-06-08 20:26:29.
A federal agency has provided a biotech company with the proper permit to release a swarm of genetically altered mosquitoes in Florida as a way to curb the spread of diseases in the area. If the company receives the additional approvals, it might begin releasing the mosquitoes this summer. The mosquitoes were bred inside the laboratories of Oxitec, a British biotech firm. The company mainly focuses on transgenically modifying mosquitoes to carry lethal genes designed to be passed onto their offspring.
What else could 2020 bring to Florida? Genetically altered, lab bred mosquitoes
12426J. Haughey, The Center Square, 2020-06-08 20:10:06.
A British biotech company has received an experimental use permit from the U.S. Environmental Protection Agency to release millions of genetically modified mosquitoes in the Florida Keys this summer. The Florida Department of Agriculture and Consumer Services and the Florida Keys Mosquito Control District (FKMCD) board must approve the permit before Oxitec can proceed. The EPA approved Oxitec’s permit May 1 despite 31,174 people objecting to it and 56 people supporting it during a 30-day comment period that expired in mid-October
BUZZ OFF! Swarm of MILLIONS of gene-hacked mosquitoes will be unleashed across USA – to wipe out malaria with ‘death sex’
12423H. Pettit, The Sun, 2020-06-08 20:08:02.
MUTANT mosquitoes created in a lab to stop the spread of deadly diseases like malaria will be unleashed across the US this summer. The gene-hacked bugs, crafted by UK biotech company Oxitec, are designed to kill off or reduce local populations of mosquitoes by mating with them.
Genetically Modified Mosquitoes Cleared For Release In The US
12432M. Horowitz, Anonymous News, 2020-06-06 20:13:38.
A company called Oxitec has received an experimental use permit from the US Environmental Protection Agency (EPA), to release genetically modified mosquitos into the wild. This would be the first time that such an experiment was attempted within the borders of the US, and the permit would allow for the release of millions of genetically modified mosquitos each week over the next two years. The genetically modified insects will be released in Florida and Texas, but they will easily be able to travel throughout the country from there.
Genetically modified mosquitoes could be released in Florida and Texas beginning this summer – silver bullet or jumping the gun?
12409B. Allan, C. Stone, H. Tuten, J. Kuzma and N. Kofler, The Conversation, 2020-06-03 18:53:50.
On May 1, 2020, the company Oxitec received an experimental use permit from the U.S. Environmental Protection Agency to release millions of GM mosquitoes (labeled by Oxitec as OX5034) every week over the next two years in Florida and Texas. Females of this mosquito species, Aedes aegypti, transmit dengue, chikungunya, yellow fever and Zika viruses. When these lab-bred GM males are released and mate with wild females, their female offspring die. Continual, large-scale releases of these OX5034 GM males should eventually cause the temporary collapse of a wild population. However, as vector biologists, geneticists, policy experts and bioethicists, we are concerned that current government oversight and scientific evaluation of GM mosquitoes do not ensure their responsible deployment.
Engineered Gene Drives for Pest Management
25478G. Miglani, Biotechnology for Plant Disease Diagnosis and Management, 2020-06-01 09:06:32.
Genes in sexually reproducing organisms normally have, on average, a 50% chance of being inherited, but some genes have a higher chance of being inherited. These genes can increase in relative frequency in a population even if they reduce the odds that each organism will reproduce. Aided by technological advances, scientists are investigating how populations might be altered by adding, disrupting, or editing genes or suppressed by propagating traits that reduce reproductive capacity. Due to the discovery of gene-drive systems in insects and with the development of gene-drive technology using engineered site-specific nucleases, the last couple of years have seen a profound rise in excitement about the many possible uses of gene drive systems (GDSs). GDSs are capable of altering the traits of wild populations and associated ecosystems. A gene drive biases the transmission of a particular allele of a gene such that it is inherited at a greater frequency than by random assortment. A consequence of gene drives is an increased frequency of specific genetic elements or alleles and their accelerated spread throughout populations over successive generations. Here we will first describe the discovery, characteristics, types and mechanisms of GDSs. Next we will deal with development of gene-drive technology and its applications with special reference to their use in pest management and progresses that have so far been made to apply gene-drive systems in this area of research followed by limitations, safety and regulatory aspects of this technology. Finally, we will take up some key questions and future prospects of this important but still under-refinement technology.
‘Just Add Water’ GM Mosquitoes Suppress Wild Population by 95%
12404H. Alber, 2020-05-27 18:49:43.
In order to reduce the spread of dengue, Oxitec releases genetically modified male Aedes mosquitoes into the environment. Once in the wild, these insects breed with local female mosquitoes and pass on a gene that causes female offspring to die at an early age. This method was reported to suppress the Aedes aegypti population by up to 96% in Brazil last year.
Genetic Biocontrol for Invasive Species
11964J. L. Teem, L. Alphey, S. Descamps, M. P. Edgington, O. Edwards, N. Gemmell, T. Harvey-Samuel, R. L. Melnick, K. P. Oh, A. J. Piaggio, J. R. Saah, D. Schill, P. Thomas, T. Smith and A. Roberts, Frontiers in Bioengineering and Biotechnology, 8:452. 2020-05-25 18:12:26.
Invasive species are increasingly affecting agriculture, food, fisheries, and forestry resources throughout the world. As a result of global trade, invasive species are often introduced into new environments where they become established and cause harm to human health, agriculture, and the environment. Prevention of new introductions is a high priority for addressing the harm caused by invasive species, but unfortunately efforts to prevent new introductions do not address the economic harm that is presently manifested where invasive species have already become established. Genetic biocontrol can be defined as the release of organisms with genetic methods designed to disrupt the reproduction of invasive populations. While these methods offer the potential to control or even eradicate invasive species, there is a need to ensure that genetic biocontrol methods can be deployed in a way that minimizes potential harm to the environment. This review provides an overview of the state of genetic biocontrol, focusing on several approaches that were the subject of presentations at the Genetic Biocontrol for Invasive Species Workshop in Tarragona, Spain, March 31st, 2019, a workshop sponsored by the OECD’s Co-operative Research Program on Biological Resource Management for Sustainable Agricultural Systems. The review considers four different approaches to genetic biocontrol for invasive species; sterile-release, YY Males, Trojan Female Technique, and gene drive. The different approaches will be compared with respect to the efficiency each affords as a genetic biocontrol tool, the practical utility and cost/benefits associated with implementation of the approach, and the regulatory considerations that will need to be addressed for each. The opinions expressed and arguments employed in this publication are the sole responsibility of the authors and do not necessarily reflect those of the OECD or of the governments of its Member countries.
RNAi: Applications in Vertebrate Pest Management
14854K. E. Horak, Trends in Biotechnology, 38:1200-1202. 2020-05-25 17:42:08.
the development of novel control technologies must be focused on species specificity and low environmental impact. Sequence-specific gene silencing via RNAi holds promise for effective management of pest wildlife.
Converting endogenous genes of the malaria mosquito into simple non-autonomous gene drives for population replacement
11465A. Hoermann, S. Tapanelli, P. Capriotti, E. K. G. Masters, T. Habtewold, G. K. Christophides and N. Windbichler, bioRxiv, 2020-05-10 15:19:12.
Here we explore how minimal genetic modifications of endogenous mosquito genes can convert them directly into non-autonomous gene drives without disrupting their expression.
Mutant mosquitoes one step closer to release in Florida, Texas this summer. Why?
11596K. Camero, The Charlotte Observer, 2020-05-07 15:45:03.
The U.S. Environmental Protection Agency (EPA) approved an experimental use permit for the British biotech company Oxitec to test the modified mosquitoes in the U.S. for the first time, according to a statement from the agency
US EPA OKs release of GM mosquitoes
11600A. Beer, Agrow Agribusiness, 2020-05-06 15:57:35.
he US EPA has granted an experimental use permit to US synthetic biology company Intrexon’s UK subsidiary, Oxitec, to test its genetically modified OX5034 Aedes aegypti mosquitoes.
Genetically Engineered Male Mosquitos to be Released in Florida and Other Parts of US to Curb Zika and Dengue Spread
11598Staff Reporter, The Science Times, 2020-05-06 15:47:02.
The Environmental Protection Agency has recently approved a new and controversial field test aimed at reducing their population.
Swarms of genetically modified mosquitoes could soon be descending on Florida
11594A. J. Dellinger, Mic, 2020-05-06 15:42:53.
Mosquitoes are a pain in the ass, so much so that the Environmental Protection Agency has approved a new and controversial field test aimed at curbing their population.
Genetic Biocontrol – An Overview (video 13.13 min)
11398GeneConvene Global Collaborative, 2020-04-25 12:41:00.
This video explains what genetic biocontrol is and surveys various technologies that can be consider genetic biocontrol technologies. It offers a conceptual organization of the various technologies based on the potential of genetic biocontrol organisms to persist and spread in an environment. This video was produced by the GeneConvene Global Colaborative.
Guidance Framework for Testing the Sterile Insect Technique as a Vector Control Tool against Aedes-Borne Diseases
12451WHO & IAEA, WHO & IAEA, 2020-04-23 20:31:06.
This document is intended to be a comprehensive guide for programme managers tasked with recommending a “go/no-go” decision on testing, full deployment and scale-up of the sterile insect technique (SIT) in regions of the world affected by diseases transmitted by Aedes mosquitoes. However, the authors hope that the material presented herein will be used more widely—by scientists, decision makers, review groups and others.
Pest control with genetically modified insects
11238myScience, myScience, 2020-04-21 17:18:07.
To control pests without pesticides, genetically modified organisms of the same species could be used. The latter carry a gene that is passed on with above-average frequency via sexual reproduction. This gene possesses traits that directly weaken the pest, or prevent pathogens from being transmitted. But how can the environmental impact of such gene-drive elements be recorded and assessed? Experts from Agroscope have authored a concept study on this topic.
Can we kill the dreaded mosquito? Do we even want to?
11228Stacey McKenna, Sierra, 2020-04-19 15:40:08.
As a major vector for disease, the mosquito has harmed more human beings than just about any other animal, and a changing climate is only boosting those numbers. As the range of disease-carrying species of mosquitoes expands, so does their ability to transmit the parasites and viruses that result in malaria, chikungunya, Zika, yellow fever, West Nile, and dengue fever. In 2018, the continental United States saw a 25 percent increase in severe, neuroinvasive cases of West Nile virus compared with a decade earlier. And over the past three decades, the CDC reports, the worldwide incidence of dengue fever has risen 30-fold.
Underdominance
11410GeneConvene Global Collaborative, 2020-04-01 13:58:43.
This video graphically explains the genetic concept of underdominance and illustrates how it can result in one allele replacing another allele in a population. While 'gene drive', underdominance is a genetic phenomenon that can be recreated using genetic technologies and might have applications as a genetic biocontrol strategy under some circumstances.
Development of control and sterilization technology for bluegill by genome editing
20100M. A. Madsen, Nippon Suisan Gakkaishi, 86:100-100. 2020-03-31 09:55:36.
This article is in Japanese
Editorial Expression of Concern: Transgenic Aedes aegypti Mosquitoes Transfer Genes into a Natural Population
16199B. R. Evans, P. Kotsakiozi, A. L. Costa-Da-Silva, R. S. Ioshino, L. Garziera, M. C. Pedrosa, A. Malavasi, J. F. Virginio, M. L. Capurro and J. R. Powell, Scientific Reports, 10:2. 2020-03-24 15:17:41.
Shortly after publication of this Article in September 2019, the Editors were alerted to concerns regarding the interpretation of the data and some of the conclusions.
Simulating effects of fitness and dispersal on the use of Trojan sex chromosomes for the management of invasive species
11488C. C. Day, E. L. Landguth, R. K. Simmons, W. P. Baker, A. R. Whiteley, P. M. Lukacs and A. Bearlin, Journal of Applied Ecology, 2020-03-19 20:15:27.
The use of Trojan Y chromosomes (TYC) for controlling invasive species involves manipulating the sex chromosomes of captive-raised individuals. Following release, the offspring of these individuals consist of only one sex, thereby skewing the sex ratio of the invasive population and potentially leading to eradication. Simulation models are needed that can inform managers about how to maximize the likelihood of invasive species eradication, since implementation of this novel management approach in the field is still rare. Here, we present the first spatially explicit, mechanistic simulation model of a real-world TYC program for invasive species eradication. Using a brook trout Salvelinus fontinalis system model, we investigated the effects of competitive and reproductive fitness of the captive-raised YY males, dispersal behaviour upon their release and landscape heterogeneity on eradication success. Likelihood of eradication was dependent on both the competitive and reproductive fitness of the Trojan individuals. Competitive fitness (i.e. survival) had a higher threshold for eradication, below which the invasive populations were not eradicated. Movement ecology of both the wild and YY male populations was important for eradication. Under a restricted dispersal scenario for YY males following their release, the wild population was not extirpated but maintained a stable, yet reduced, population size. Analysis of landscape configuration indicated that time to eradication of local patches increased with greater connectivity within the stream network. In addition to sex ratio distortion, density-dependent mortality resulting from outplantings made an important contribution to population decline and therefore may also affect native competitors. Synthesis and applications. The use of Trojan sex chromosomes to skew population sex ratios is a novel method for the suppression and eradication of aquatic invasive species. Results from our modelling work indicate that while eradication is possible, maximizing its likelihood requires an understanding of the fitness and movement ecology of both the wild and YY male populations of the invasive species. Both our model and the principles derived from this study related to fitness and behavioural landscape ecology can be broadly applied to other invaded species and systems.
The Buzz About Genetically Modified Mosquitoes – a podcast
7932The Scientist Creative Services Team, The Scientist, podcast. 2020-02-26 18:17:44.
Mosquito-borne diseases afflict a large portion of the world. In this month’s episode, we consider genetic methods to eradicate diseases such as Zika fever, Dengue fever, and malaria. We spoke with Omar Akbari, professor of Cell and Developmental Biology at the University of California, San Diego, to learn more.
Understanding the Science of Gene Drive and the Potential for an Improved Crop Pest Control System in Nigeria
14882A. Isah and R. S. M. Gidado, OFAB Nigeria, 2020-02-26 15:52:39.
Several studies have shown that the Cas9-mediated gene drive technology is cheaper and will be easily affordable by the efficient Nigerian scientists to explore. The application of the gene drive technologies have many more controls over several other devastating insects in Nigeria and may be very necessary to adopt it to rescue our ailing food crop industry from the attack by destructive insect pest of crops.
Genetically engineered moths may save kale chips
7357C. Poku, BIOtechNOW, 2020-02-07 21:49:10.
Sea salt kale chips, bacon brussels sprouts, and buffalo cauliflower wings are under threat. Environmental activists will have you believe the biggest threat to our food system is pesticides. That’s not true, in fact, it’s insects—the very reason most pesticides are necessary. Insects are such a dangerous issue that Somalia recently declared a state of emergency as an “unprecedented” swarm of locusts is raising alarms about famine. Climate change has led to a rampant increase in bugs like locusts and moths, that threaten our food, and mosquitoes and ticks, that threaten people. A recent CNN article explains that diamondback moths are one of the most damaging insects because of their high reproduction rate and resistance to most insecticides.
Genetically engineered moths have been released into the wild to wipe out pests
7360K. Rogers, CNN, 2020-02-03 21:55:17.
Genetically modified diamondback moths designed to wipe out wild pest populations were released in fields for the first time in New York state. Diamondback moths are migratory pests found in the Americas, Europe, New Zealand and Southeast Asia, but especially in areas where crops can be grown yearround. In these parts -- where it's not too hot nor too cold -- are where diamondback moths cause the greatest problems, including billions of dollars in damages to cruciferous crops such as cabbage, broccoli, cauliflower and canola. They're one of the most damaging insects because of their high reproduction rate and resistance to most insecticides.
Genetically modified butterflies could herald a new era in crop protection
7245Science News,, Science News, 2020-02-01 16:02:30.
New study highlights successful test including field release of genetically modified butterflies. Scientists believe this success could pave the way for an effective and sustainable approach to pest control in crops. The butterfly in question is the cruciferous moth ( Plutella xylostella ), or cabbage moth, a species of moth (butterfly) of the family Plutellidae. The agricultural industry has been trying for decades to find organic and environmentally friendly ways to fight the cruciferous moth, a species largely resistant to insecticides.
Engineered symbionts activate honey bee immunity and limit pathogens
19387P. Leonard Sean, J. E. Powell, J. Perutka, P. Geng, C. Heckmann Luke, D. Horak Richard, W. Davies Bryan, D. Ellington Andrew, E. Barrick Jeffrey and A. Moran Nancy, Science, 367:573-576. 2020-01-31 17:14:03.
Honey bees are essential pollinators threatened by colony losses linked to the spread of parasites and pathogens. Here, we report a new approach for manipulating bee gene expression and protecting bee health. We engineered a symbiotic bee gut bacterium, Snodgrassella alvi, to induce eukaryotic RNA interference (RNAi) immune responses. We show that engineered S. alvi can stably recolonize bees and produce double-stranded RNA to activate RNAi and repress host gene expression, thereby altering bee physiology, behavior, and growth. We used this approach to improve bee survival after a viral challenge, and we show that engineered S. alvi can kill parasitic Varroa mites by triggering the mite RNAi response. This symbiont-mediated RNAi approach is a tool for studying bee functional genomics and potentially for safeguarding bee health.
World’s First Genetically Modified Moths Released to Nature
7248M. Cage, SOMAG News, 2020-01-30 16:07:06.
There are many insect species that harm agricultural products in the world. One of them is diamond moths. Genetically modified moths were used to control these moths, which are harmful to many plants. Plutella xylostella or also known as diamond moths; One of the most harmful and destructive insects for plants such as cauliflower, cabbage, broccoli and canola. This creature, which is also very resistant to pesticides, causes great damage to the plants it dips. Especially in China, this insect seriously undermines the growing of cabbage, one of the country’s most important crops.
GMO diamondback moth shows promise as sustainable pest control tool in first ever open-field release
7262Cornell University, Genetic Literacy Project, 2020-01-29 16:35:41.
A newly published study reports a successful, first-ever open-field release of a self-limiting, genetically engineered diamondback moth, stating that it paves the way for an effective and sustainable approach to pest control. The diamondback moth, also known as Plutella xylostella, is highly damaging to brassica crops such as cabbage, broccoli, cauliflower and canola. This new strain of diamondback moth, developed by Oxitec Ltd, is modified to control pest diamondback moth in a targeted manner. The study showed the engineered strain had similar field behaviors to unmodified diamondback moths, with results offering promise for future protection of farmers’ brassica crops.
Scientists have released genetically modified moths
7259N. Kumar, The Times Hub, 2020-01-29 16:32:32.
In the US, the researchers decided to test emerging from genetic modification Diamondback moth, placing it in field conditions. The work was conducted by experts from new York, representing Cornell University.
GM Insects on the Horizon
7256E. Unglesbee, Progressive Farmer, 2020-01-29 16:22:18.
Diamondback moths would do well to be wary of potential mates in the years to come. Scientists recently completed the first successful field testing of a genetically modified (GM) "self-limiting" insect in the U.S., using this species. When the GM male diamondback moths are released and mate with wild female moths, they pass on a gene that causes all female offspring from the match to die in the early larval stages.
Male moths genetically modified to kill females released in the wild
7253M. Le Page, New Scientist, 2020-01-29 16:14:01.
Genetically modified male diamondback moths designed to wipe out pest populations have been released in New York state. The field trial shows that these GM moths, whose female offspring die soon after hatching, could help control this major crop pest. Oxitec, the British biotechnology company behind the trial, has already carried out field trials of this method for controlling mosquitoes that spread diseases such as dengue. However, the moth field trial is the first for a crop pest, the company says.
First Field Release of a Genetically Engineered, Self-Limiting Agricultural Pest Insect: Evaluating Its Potential for Future Crop Protection
7251A. M. Shelton, S. J. Long, A. S. Walker, M. Bolton, H. L. Collins, L. Revuelta, L. M. Johnson and N. I. Morrison, Frontiers in Bioengineering and Biotechnology, 7:1-15. 2020-01-29 16:10:21.
Alternative, biologically-based approaches for pest management are sorely needed and one approach is to use genetically engineered insects. Herein we describe a series of integrated field, laboratory and modeling studies with the diamondback moth, Plutella xylostella, a serious global pest of crucifers. A “self-limiting” strain of Plutella xylostella (OX4319L), genetically engineered to allow the production of male-only cohorts of moths for field releases, was developed as a novel approach to protect crucifer crops. Wild-type females that mate with these self-limiting males will not produce viable female progeny. Our previous greenhouse studies demonstrated that releases of OX4319L males lead to suppression of the target pest population and dilution of insecticide-resistance genes. We report results of the first open-field release of a non-irradiated, genetically engineered self-limiting strain of an agricultural pest insect. In a series of mark-release-recapture field studies with co-releases of adult OX4319L males and wild-type counterparts, the dispersal, persistence and field survival of each strain were measured in a 2.83 ha cabbage field. In most cases, no differences were detected in these parameters. Overall, 97.8% of the wild-type males and 95.4% of the OX4319L males recaptured dispersed <35 m from the release point. The predicted persistence did not differ between strains regardless of release rate. With 95% confidence, 75% of OX4319L males released at a rate of 1,500 could be expected to live between 3.5 and 5.4 days and 95% of these males could be expected to be detected within 25.8–34.9 m from the release point. Moth strain had no effect on field survival but release rate did. Collectively, these results suggest similar field behavior of OX4319L males compared to its wild-type counterpart. Laboratory studies revealed no differences in mating competitiveness or intrinsic growth rates between the strains and small differences in longevity. Using results from these studies, mathematical models were developed that indicate release of OX4319L males should offer efficacious pest management of P. xylostella. Further field studies are recommended to demonstrate the potential for this self-limiting P. xylostella to provide pest suppression and resistance management benefits, as was previously demonstrated in greenhouse studies.
Public Opinion Towards Gene Drive as a Pest Control Approach for Biodiversity Conservation and the Association of Underlying Worldviews
7348E. A. MacDonald, J. Balanovic, E. D. Edwards, W. Abrahamse, B. Frame, A. Greenaway, R. Kannemeyer, N. Kirk, F. Medvecky, T. L. Milfont, J. C. Russell and D. M. Tompkins, Environmental Communication-a Journal of Nature and Culture, 15:1-16. 2020-01-27 21:27:11.
Synthetic gene drive approaches are nascent technologies with potential applicability for pest control for conservation purposes. Responsible science mandates that society be engaged in a dialogue over new technology, particularly where there exist global ramifications as with gene drive. We hypothesize that public attitudes towards gene drive are not formed on scientific knowledge or demographics alone, but are heavily influenced by underlying worldviews, which encapsulate a broad and interactive system of attitudes, beliefs, and values. To test this, we conducted a national survey in New Zealand (n = 8199) and found that respondents clustered into four distinct segments with underlying worldviews, better able to explain attitudes toward gene drive than either the participants' scientific knowledge or other explanatory factors such demographics, political ideology or religiosity. We found that the use of gene drive for biodiversity conservation currently has moderate (32%) levels of support in New Zealand but that varied substantially across the four segments. Should gene drive become a technically viable approach for pest control, understanding the worldviews that shape public decision-making can guide a more empathetic engagement process and empower society to participate in informed decision-making about if and how gene drive should be used for conservation purposes.
The potential cost-effectiveness of controlling dengue in Indonesia using wMel Wolbachia released at scale: a modelling study
14326O. J. Brady, D. D. Kharisma, N. N. Wilastonegoro, K. M. Reilly, E. Hendricx, L. S. Bastos, L. Yakob and D. S. Shepard, medRxiv, 2020.01.11.20017186. 2020-01-16 17:55:32.
Wolbachia releases in high density urban areas is expected to be highly cost-effective and could potentially be the first cost saving intervention for dengue. Sites with strong public health infrastructure, fiscal capacity, and community support should be prioritized.
Optimal control and analysis of a modified trojan Y-Chromosome strategy
11491M. A. Beauregard, R. D. Parshad, S. Boon, H. Conaway, T. Griffin and J. J. Lyu, Ecological Modelling, 416. 2020-01-15 20:19:52.
The Trojan Y Chromosome (TYC) strategy is a promising eradication method that attempts to manipulate the female to male ratio to promote the reduction of the population of an invasive species. The manipulation stems from an introduction of sex-reversed males, called supermales, into an ecosystem. The offspring of the supermales is guaranteed to be male. Mathematical models have shown that the population can be driven to extinction with a continuous supply of supermales. In this paper, a new model of the TYC strategy is introduced and analyzed that includes two important modeling characteristics, that are neglected in all previous models. First, the new model includes intraspecies competition for mates. Second, a strong Allee effect is included. Several conclusions about the strategy via optimal control are established. These results have large scale implications for the biological control of invasive species.
A typology of community and stakeholder engagement based on documented examples in the field of novel vector control
6032C. E. Schairer, R. Taitingfong, O. S. Akbari and C. S. Bloss, PLoS Neglected Tropical Diseases, 13:e0007863. 2019-12-30 20:46:44.
Background Despite broad consensus on the importance of community and stakeholder engagement (CSE) for guiding the development, regulation, field testing, and deployment of emerging vector control technologies (such as genetically engineered insects), the types of activities pursued have varied widely, as have the outcomes. We looked to previous CSE efforts for clarity about appropriate methods and goals. Our analysis yielded a typology of CSE, and related vocabulary, that describes distinctions that funders, organizers, and scholars should make when proposing or evaluating CSE. Methods We compiled available formal documentation of CSE projects, starting with projects mentioned in interviews with 17 key informants. Major features of these examples, including the initiators, target groups, timing, goals, and methods were identified using qualitative coding. Based on these examples, subcategories were developed for a subset of features and applied to the identified cases of CSE in the documents. Co-occurrence of subcategorized features was examined for patterns. Results We identified 14 documented examples CSE projects, which were comprised of 28 distinct CSE activities. We found no clear patterns with respect to timing. However, we found that grouping examples according to whether initiators or targets could enact the immediate desired outcome could help to clarify relationships between goals, methods, and targets.
The potential for a released autosomal X-shredder becoming a driving-Y chromosome and invasively suppressing wild populations of malaria mosquitoes
5648Alcalay, Y., S. Fuchs, R. Galizi, F. Bernardini, R. E. Haghighat-Khah, D. B. Rusch, J. R. Adrion, M. W. Hahn, P. Tortosa and P. A. Papathanos, bioRxiv, 2019:860551. 2019-12-17 17:51:02.
Synthetic sex-ratio distorters based on X-chromosome shredding are predicted to be more efficient than sterile males for population suppression of malaria mosquitoes using genetic control. X chromosome shredding operates through the targeted elimination of X-chromosome-bearing gametes during male spermatogenesis, resulting in males that have a high fraction of male offspring. Strains harboring autosomal constructs containing a modified endonuclease I-PpoI have now been developed in the malaria mosquito Anopheles gambiae, resulting in strong sex-ratio distortion towards males. Data are being gathered for these strains for submission of regulatory dossiers for contained use and subsequent field release in West Africa. Since autosomal X shredders are transmitted in a Mendelian fashion and can be selected against their frequency in the population is expected to decline once releases are halted. However, any unintended transfer of the X-shredder to the Y-chromosome could theoretically change these dynamics: This could lead to 100% transmission of the newly Y-linked X-shredder to the predominant male-biased offspring and its insulation from negative selection in females, resulting in its potential spread in the population and ultimately to suppression. Here, we analyze plausible mechanisms whereby an autosomal X-shredder could become linked to the Y-chromosome after release and provide data regarding its potential for activity should it become linked to the Y-chromosome. Our results strongly suggest that Y-chromosome linkage through remobilization of the transposon used for the initial genetic transformation is unlikely, and that, in the unexpected event that the X-shredder becomes linked to the Y-chromosome, expression and activity of the X-shredder would likely be inhibited by meiotic sex chromosome inactivation. We conclude that a functioning X-shredding based Y-drive resulting from a naturally induced transposition or translocation of the transgene onto the Y-chromosome is unlikely.
Mass-Rearing of Drosophila suzukii for Sterile Insect Technique Application: Evaluation of Two Oviposition Systems
17766F. Sassù, K. Nikolouli, S. Caravantes, G. Taret, R. Pereira, M. J. B. Vreysen, C. Stauffer and C. Cáceres, Insects, 10. 2019-12-12 15:07:36.
Drosophila suzukii (Diptera: Drosophilidae) is an invasive pest of a wide range of commercial soft-skinned fruits. To date, most management tactics are based on spraying of conventional and/or organic insecticides, baited traps, and netting exclusion. Interest has been expressed in using the sterile insect technique (SIT) as part of area-wide integrated pest management (AW-IPM) programs to control D. suzukii infestations. Mass-rearing protocols are one of the prerequisites for successful implementation of the SIT. To establish mass-rearing methods for this species, two different egg-collection systems were developed and compared with respect to the number of eggs produced, egg viability, pupa and adult recovery, adult emergence rate, and flight ability. Female flies kept in cages equipped with a wax panel produced significantly more eggs with higher viability and adult emergence rate, as compared to the netted oviposition system. The wax panel system was also more practical and less laborious regarding the collection of eggs. Furthermore, the wax panel oviposition system can be adapted to any size or design of an adult cage. In conclusion, this system bears great promise as an effective system for the mass production of D. suzukii for SIT.
An Initial Framework for the Environmental Risk Assessment of Synthetic Biology-Derived Organisms with a Focus on Gene Drives.
16281W. G. Landis, E. A. Brown and S. Eikenbary, Synthetic Biology 2020: Frontiers in Risk Analysis and Governance. Risk, Systems and Decisions., 2019-11-29 17:16:37.
We apply the structure of source-stressor-habitat-effect-impact pathway derived from the relative risk model (Landis and Wiegers 2005) and as was demonstrated to be applicable in the National Academy of Sciences, Engineering and Medicine (NASEM) 2016 report Gene Drives on the Horizon. This relative risk model is now calculated employing Bayesian networks and has been applied to forestry management (Ayre and Landis 2012), infectious disease (Ayre et al. 2014), invasive species (Herring et al. 2015), contaminated sites (Landis et al. 2017a; Johns et al. 2017), and watershed management (Hines and Landis 2014; Graham et al. 2019).
Malaysia Wolbachia trials: Battling dengue and other mosquito-borne viruses
170592019-11-22 13:47:09.
Establishment of Wolbachia Strain wAlbB in Malaysian Populations of Aedes aegypti for Dengue Control
17089W. A. Nazni, A. A. Hoffmann, A. NoorAfizah, Y. L. Cheong, M. V. Mancini, N. Golding, G. M. R. Kamarul, M. A. K. Arif, H. Thohir, H. NurSyamimi, M. Z. ZatilAqmar, M. NurRuqqayah, A. NorSyazwani, A. Faiz, F.-R. M. N. Irfan, S. Rubaaini, N. Nuradila, N. M. N, Current Biology, 29:4241-4248.e5. 2019-11-21 15:20:44.
Dengue has enormous health impacts globally. A novel approach to decrease dengue incidence involves the introduction of Wolbachia endosymbionts that block dengue virus transmission into populations of the primary vector mosquito, Aedes aegypti. The wMel Wolbachia strain has previously been trialed in open releases of Ae. aegypti; however, the wAlbB strain has been shown to maintain higher density than wMel at high larval rearing temperatures. Releases of Ae. aegypti mosquitoes carrying wAlbB were carried out in 6 diverse sites in greater Kuala Lumpur, Malaysia, with high endemic dengue transmission. The strain was successfully established and maintained at very high population frequency at some sites or persisted with additional releases following fluctuations at other sites. Based on passive case monitoring, reduced human dengue incidence was observed in the release sites when compared to control sites. The wAlbB strain of Wolbachia provides a promising option as a tool for dengue control, particularly in very hot climates.
Genetic control of Invasive carp
13941MAISRC, Minnesota Aquatic Invasive Species Research Center, 2019-10-16 15:08:53.
This project focuses on a novel method of biocontrol for common carp which will complement existing technologies by introducing a synthetic species-like barrier to reproduction. Researchers will use programmable transcription activators to drive lethal embryonic overexpression of endogenous genes in hybrid embryos.
Peri-Urban Community Attitudes towards Codling Moth Trapping and Suppression Using the Sterile Insect Technique in New Zealand
17774G. Paterson, G. L. W. Perry, J. T. S. Walker and D. M. Suckling, Insects, 10. 2019-10-09 15:21:37.
New, more socially-acceptable technologies are being developed to suppress horticultural pests, because suppression is technically difficult with current technologies, especially in urban areas. One technique involves the release of sterile insects to prevent offspring in the next generation. This technology involves aerial or ground release systems, but this could also create issues for the public. This study investigated community perceptions of a recently-introduced response to codling moth control in New Zealand—Sterile Insect Technique (SIT). Community attitudes to SIT were examined in Hastings, New Zealand, in April, 2018. Eighty-six detailed interviews were undertaken with a random sample of households. This community was very willing (98% agreement) to host a sex pheromone trap in their gardens, and condoned regular visits to monitor traps. Attitudes to SIT were very positive (98% in favor). Once explained, the concept of using unmanned aerial vehicles to deliver sterile insects was also acceptable (98%) to the community. Use of unmanned aerial vehicles to release sterile insects during a hypothetical incursion response of an exotic fruit fly was also supported at 98% by respondent householders. Investigation of community attitudes can be valuable to guide practitioners in determining suitable technologies before an area-wide programme is launched.
Transgenic Aedes aegypti Mosquitoes Transfer Genes into a Natural Population
16197B. R. Evans, P. Kotsakiozi, A. L. Costa-da-Silva, R. S. Ioshino, L. Garziera, M. C. Pedrosa, A. Malavasi, J. F. Virginio, M. L. Capurro and J. R. Powell, Scientific Reports, 9:6. 2019-09-10 15:09:04.
We genotyped the release strain and the target Jacobina population before releases began for >21,000 single nucleotide polymorphisms (SNPs). Genetic sampling from the target population six, 12, and 27-30 months after releases commenced provides clear evidence that portions of the transgenic strain genome have been incorporated into the target population. Evidently, rare viable hybrid offspring between the release strain and the Jacobina population are sufficiently robust to be able to reproduce in nature. The release strain was developed using a strain originally from Cuba, then outcrossed to a Mexican population. Thus, Jacobina Ae. aegypti are now a mix of three populations. It is unclear how this may affect disease transmission or affect other efforts to control these dangerous vectors. These results highlight the importance of having in place a genetic monitoring program during such releases to detect un-anticipated outcomes.
Engineered action at a distance: Blood-meal-inducible paralysis in Aedes aegypti
16651R. E. Haghighat-Khah, T. Harvey-Samuel, S. Basu, O. StJohn, S. Scaife, S. Verkuijl, E. Lovett and L. Alphey, PLOS Neglected Tropical Diseases, 13:e0007579. 2019-09-03 20:37:29.
Here we demonstrate that it is possible to engineer ‘non-cell autonomous’ effectors–that is where the effect (e.g. the action of a toxic protein) can act on cells distant from the tissues in which they are originally expressed. To achieve this we utilised the endogenous cell secretory pathway to engineer a novel control phenotype–blood-meal inducible (i.e. late-acting, female-specific) reversible paralysis. The logic behind engineering such ‘action at a distance’ phenotypes will extend to a variety of other pest insects and control phenotypes.
Incompatible and sterile insect techniques combined eliminate mosquitoes
16263X. Zheng, D. Zhang, Y. Li, C. Yang, Y. Wu, X. Liang, Y. Liang, X. Pan, L. Hu, Q. Sun, X. Wang, Y. Wei, J. Zhu, W. Qian, Z. Yan, A. G. Parker, J. R. L. Gilles, K. Bourtzis, J. Bouyer, M. Tang, B. Zheng, J. Yu, J. Liu, J. Zhuang, Z. Hu, M. Zhang, J.-T. Gon, 572, 56-61. 2019-07-17 16:15:33.
Here we show that combining incompatible and sterile insect techniques (IIT–SIT) enables near elimination of field populations of the world’s most invasive mosquito species, Aedes albopictus. Millions of factory-reared adult males with an artificial triple-Wolbachia infection were released, with prior pupal irradiation of the released mosquitoes to prevent unintentionally released triply infected females from successfully reproducing in the field. This successful field trial demonstrates the feasibility of area-wide application of combined IIT–SIT for mosquito vector control.
Sex Sorting for Pest Control: It’s Raining Men!
17064C. Lutrat, D. Giesbrecht, E. Marois, S. Whyard, T. Baldet and J. Bouyer, Trends in Parasitology, 35:649-662. 2019-06-26 14:04:15.
In the pursuit of better pest- and vector-control strategies, attention returns to an old proven technology, the sterile insect technique (SIT) and related insect population-suppression methods. A major obstacle for any of these approaches that involves the release of sterile males is the separation of males from females during the mass rearing stage, in order to improve the cost-efficiency of these methods and to prevent the release of biting and disease-vectoring females. This review describes recent sex-sorting developments in dipteran flies with an emphasis on assessing the suitability of these methods for large-scale rearing of male vectors for mass release.
Biological control of pests and a social model of animal welfare
16284A. Mankad, U. Kennedy and L. Carter, Journal of Environmental Management, 247:313-322. 2019-06-25 17:21:12.
We consider the role of perceived humaneness or, more accurately, animal welfare as it relates to managing invasive species from a scientific and social perspective. In order to highlight and articulate particular nuances and standards across different pest control contexts, we use three case examples (feral cats, wild rabbits, and invasive cane toads) and explore where biological pest control and animal welfare interests intersect.
The association between mitochondrial genetic variation and reduced colony fitness in an invasive wasp
13731J. Dobelmann, A. Alexander, J. W. Baty, N. J. Gemmell, M. A. M. Gruber, O. Quinn, T. Wenseleers and P. J. Lester, Molecular Ecology, 28:3324-3338. 2019-06-24 19:25:29.
Despite the mitochondrion's long-recognized role in energy production, mitochondrial DNA (mtDNA) variation commonly found in natural populations was assumed to be effectively neutral. However, variation in mtDNA has now been increasingly linked to phenotypic variation in life history traits and fitness. We examined whether the relative fitness in native and invasive common wasp (Vespula vulgaris) populations in Belgium and New Zealand (NZ), respectively, can be linked to mtDNA variation.
A synthetic male-specific sterilization system using the mammalian pro-apoptotic factor in a malaria vector mosquito
16645D. S. Yamamoto, M. Sumitani, K. Kasashima, H. Sezutsu, H. Matsuoka and H. Kato, Scientific Reports, 9:11. 2019-06-03 19:52:01.
We produced a transgenic mosquito line that expresses mouse Bax under the control of this testis-specific promoter. Transgenic mosquito males exhibited aberrant testes without functional sperm and complete sterility, whereas transgenic females maintained normal fecundity. Despite their abnormal testes, the transgenic males maintained normal function of male accessory glands and typical mating behaviour. As a result of mating with these males, females showed refractoriness to further mating. These results suggest that transgenic males induce female sterility via mating. The mosquito is one of the most important disease vectors, and the control of their population benefits global public health.
Genetic pest management technologies to control invasive rodents
11576D. Kanavy and D. Threadgill, Island invasives: scaling up to meet the challenge, 2019-03-05 15:20:05.
Many strategies exist to manage invasive pests on islands, ranging from poison to trapping, with varying degrees of success. Genetic technologies are increasingly being applied to insect pests, but so far, not to vertebrates. We are implementing a genetic strategy to eradicate invasive mouse populations as another tool for pest control. Mus musculus, the common house mouse, is one of the most widespread invasive species. Mice threaten human health, agriculture, and biodiversity on many islands, particularly seabirds. Seabirds are endangered indirectly through competition for resources or predators being attracted by the mice or directly with mice attacking chicks and eggs. Rodenticides are the most common method of eradicating mice, but their use leads to poisoning of non-target species and has limited efficacy against mice. An approach that could eliminate non-target species impact would be to engineer daughterless mice linked to a gene drive system for self-sustained propagation. For this project, we have investigated exploiting a naturally occurring gene drive, the t-complex. Using the t w2 haplotype of the t-complex, we observed the t w2 haplotype being transmitted to offspring with a transmission distortion ratio of 95.3%. The daughterless phenotype is being accomplished by inserting the Sry gene (male sex-determining gene) into an autosome containing the tw2 haplotype via CRISPR/Cas9 gene editing. The presence of Sry will induce testis formation, regardless of the sex chromosomes naturally inherited. When Sry is inserted into the t-complex, the desired gene will spread through the population, eliminating female offspring. This model system will support studies to evaluate the effectiveness of crashing an invasive population without adversely affecting other
Trialling gene drives to control invasive species: what, where and how?
11573T. Harvey-Samuel, K. J. Campbell, M. Edgington and L. Alphey, Island invasives: scaling up to meet the challenge, 2019-03-05 15:16:48.
The control of invasive species would be enhanced through the addition of novel, more effective and sustainable pest management methods. One control option yet to be trialled in the field is to deploy transgene-based ‘Gene Drives’: technologies which force the inheritance of a genetic construct through the gene pool of a wild population, suppressing it or replacing it with a less harmful form. There is considerable interest in applying gene drives to currently intractable invasives across a broad taxonomic range. However, not all species will make efficient or safe targets for these technologies. Additionally, the safety and efficacy of these systems will vary according to where they are deployed, the specific molecular design chosen, and how these factors interact with the ecology of the target pest. Given the transformative but also controversial nature of gene drives, it is imperative that their first field trials are able to successfully demonstrate that they can be used safely and efficiently. Here, we discuss how to maximise the probability of this outcome through considering three important questions: What types of invasive species should we use to trial gene drives? Where should we be trialling them? and How should these trials be conducted? In particular, we focus on the ecological, genetic and geographic features of small, isolated islands which make them ideal locations for these initial trials. A case study of an island invasive that is deemed highly appropriate for gene drive intervention, and for which gene drive development is currently underway (Mus musculus), is used to further explore these concepts
Towards a genetic approach to invasive rodent eradications: assessing reproductive competitiveness between wild and laboratory mice
11570M. Serr, N. Heard and J. Godwin, Island invasives: scaling up to meet the challenge, 2019-03-05 15:10:12.
House mice are significant invasive pests, particularly on islands without native mammalian predators. As part of a multi-institutional project aimed at suppressing invasive mouse populations on islands, we aim to create heavily male-biased sex ratios with the goal of causing the populations to crash. Effective implementation of this approach will depend on engineered F1 wild-lab males being effective secondary invaders that can mate successfully. As a first step in assessing this possibility, we are characterising genetic and behavioural differences between Mus musculus strains in terms of mating and fecundity using wild house mice derived from an invasive population on the Farallon Islands (MmF), a laboratory strain C57BL/6/129 (tw2), and F1 wild-lab off spring. Mice with the ‘t allele’ (tw2) have a naturally occurring gene drive system. To assess fertility in F1 wild-lab crosses, tw2 males were paired with wild-derived females from the Farallon Islands (MmF). Results of these matings indicate litter sizes are comparable but that weaned pup and adult wild-lab mice are heavier in mass. Next, we initiated tests of male competitiveness using larger (3 m2 ) enclosures with enrichment. We introduced both an MmF and a tw2-bearing male to two MmF females to assess mating outcomes. Preliminary results of these experiments show none of the offspring carried the t-allele. However, performing the same experiment with F1 wildlab males instead of a full lab background resulted in 70% of off spring carrying the t w2 allele. This indicates that F1 wildlab males may be able to successfully compete and secondarily invade. It will be important in subsequent experiments to determine what characteristics contribute to secondary invasion success. More generally, a better understanding of characteristics contributing to overall success in increasingly complex and naturalistic environments will be critical in determining the potential of a gene drive-based eradication approach for invasive mice on islands
A potential new tool for the toolbox: assessing gene drives for eradicating invasive rodent populations
11550K. J. Campbell, J. R. Saah, P. R. Brown, J. Godwin, F. Gould, G. R. Howald, A. Piaggio, P. Thomas, D. M. Tompkins, D. Threadgill, J. Delborne, D. Kanavy, T. Kuiken, H. Packard, M. Serr and A. Shiels, Island invasives: scaling up to meet the challenge, 2019-03-05 14:59:34.
Invasive rodents have significant negative impacts on island biodiversity. All but the smallest of rodent eradications currently rely on island-wide rodenticide applications. Although signifi cant advances have been made in mitigating unintended impacts, rodent eradication on inhabited islands remains extremely challenging. Current tools restrict eradication eff orts to fewer than 15% of islands with critically endangered or endangered species threatened by invasive rodents. The Genetic Biocontrol of Invasive Rodents partnership is an interdisciplinary collaboration to develop and evaluate gene drive technology for eradicating invasive rodent populations on islands. Technological approaches currently being investigated include the production of multiple strains of Mus musculus with a modifi ed form of the native t-complex, or a CRISPR gene drive, carrying genes or mechanisms that determine sex. These systems have the potential to skew the sex ratio of off spring to approach 100% single-sex, which could result in population collapse. One goal proposed is to test the ability of constructs to spread and increase in frequency in M. musculus populations in biosecure, captive settings and undertake modelling to inform development and potential deployment of these systems. Structured ecologically-based risk assessments are proposed, along with social and cultural engagement to assess the acceptability of releasing a gene drive system. Work will be guided by an external ethics advisory board. Partners are from three countries with significant regulatory capacity (USA, Australia, New Zealand). Thus, we will seek data sharing agreements so that results from experiments may be used within all three countries and treat regulatory requirements as a minimum. Species-specific, scalable, and socially acceptable new eradication tools could produce substantial biodiversity benefits not possible with current technologies. Gene drive innovation may provide such a tool for invasive species management and be potentially transformative and worthy of exploring in an inclusive, responsible, and ethical manner.
Ecological effects on underdominance threshold drives for vector control
16267D. Khamis, C. El Mouden, K. Kura and M. B. Bonsall, Journal of Theoretical Biology, 456:1-15. 2018-11-07 16:39:27.
Here, ecological and epidemiological dynamics are coupled to a model of mosquito genetics to investigate theoretically the impact of different types of underdominance gene drive on disease prevalence. We model systems with two engineered alleles carried either on the same pair of chromosomes at the same locus or homozygously on different pairs at different loci, genetic lethality that affects both sexes or only females, and bi-sex or male-only releases.
Population Consequences of Releasing Sex-Reversed Fish: Applications and Concerns
11500C. Wederkind, Sex Control in Aquaculture, Chp 8:179-188. 2018-11-02 20:38:44.
Sex differentiation is generally more labile in gonochoristic fish than it is, for example, in birds and mammals. Environmentally induced sex reversal is, therefore, often possible, and creates genotype‐phenotype mismatches that can be useful in population management. Interestingly, sex chromosomes of fish are typically not significantly decayed (i.e., all types of offspring of sex‐reversed individuals may be viable, including YY and WW individuals that can then often be sex reversed again). Releasing sex‐reversed fish, or releasing untreated YY and WW offspring of sex‐reversed fish, into natural populations can, therefore, affect the sex ratio of the population in the following generations and, hence, affect population growth.
Invasion Success and Management Strategies for Social Vespula Wasps
13740P. J. Lester and J. R. Beggs, Annual Review of Entomology, 64:51-71. 2018-09-26 19:38:03.
Three species of Vespula have become invasive in Australia, Hawai'i, New Zealand, and North and South America and continue to spread. Economically, their main negative effect is associated with pollination and the apicultural industry. Climate change is likely to exacerbate their impacts in many regions. Although investigated extensively, no effective biological control agents have yet been found. Emerging technologies such as gene drives are under consideration.
A spatially discrete, integral projection model and its application to invasive carp
11503R. A. Erickson, E. A. Eager, P. M. Kocovsky, D. C. Glover, J. L. Kallis and K. R. Long, Ecological Modelling, 387:163-171. 2018-09-21 20:46:26.
Natural resource managers and ecologists often desire an understanding of spatial dynamics such as migration, dispersion, and meta-population dynamics. Network-node models can capture these salient features. Additionally, the state-variable used with many species may be appropriately modeled as a continuous variable (e.g., length) and management activities sometimes can only target individuals of certain sizes. Integral projection models (IPMs) can capture this life history characteristic and allow for the examination of size-specific management. We combined an IPM with a network-node model to capture both of these salient features. We then demonstrated how this model could be used to understand and manage populations of invasive species focusing on grass carp as an example. Grass carp disrupt ecosystems outside of their native range and have spread around much of the world, including North America. The impacts of grass carp include adversely changing aquatic plant communities, which in turn affect a wide range of endpoints ranging from water quality to waterfowl recruitment. We specifically examined two theoretical systems using parameters from the literature. First, we modeled a lake with two tributaries and examined how modified sterile males could be used as a control tool. We found that modified sterile males may be a feasible control tool to limit population growth. Second, we modeled a series of river pools and examined how harvest and deterrents could be used to decrease the risk of expanding grass carp's range within a river system. Within this system, we also compared the impacts of size specific harvest and uniform harvest across all sizes. We found that targeting the largest, spawning populations may be more important than targeting the populations close to the invasion front for reducing the risk of spreading grass carp. We also demonstrate that size of harvested fish was important for controlling populations.
Pest demography critically determines the viability of synthetic gene drives for population control
11505K. E. Wilkins, T. A. A. Prowse, P. Cassey, P. Q. Thomas and J. V. Ross, Mathematical Biosciences, 305:160-169. 2018-09-13 20:48:39.
Synthetic gene drives offer a novel solution for the control of invasive alien species. CRISPR-based gene drives can positively bias their own inheritance, and comprise a DNA sequence that is replicated by homologous recombination. Since gene drives can be positioned to silence fertility or developmental genes, they could be used for population suppression. However, the production of resistant alleles following self-replication errors threatens the technology's viability for pest eradication in real-world applications. Further, a robust assessment of how pest demography impacts the expected progression of gene drives through populations is currently lacking. We used a deterministic, two-sex, birth-death model to investigate how demographic assumptions affect the efficiency of suppression drives for controlling invasive rodents on islands, for two different gene-drive strategies. We show that mass-action reproduction results in overly optimistic eradication outcomes when compared to the more realistic assumption of polygynous breeding. When polygyny was assumed, both gene-strategies failed due to the evolution of resistance unless a reproductive Allee effect (reduced reproductive rates at low population density) was also included; although model outcomes were highly sensitive to the strength of this effect. Increasing the size of the initial gene-drive introduction (up to 10% of carrying capacity) had little impact on population outcomes. Understanding the demography of a population targeted for eradication is critical before the viability of gene-drive suppression can be adequately assessed.
Sex determination in Neotropical fish: Implications ranging from aquaculture technology to ecological assessment
11495J. I. Fernandino and R. S. Hattori, General and Comparative Endocrinology, 273:172-183. 2018-07-07 20:24:06.
The high biodiversity of fish in the Neotropical region contrasts with scarce or biased studies on the mechanisms involved in the sex determination in members of this fauna. In this review, we attempted to compile the information available on determination, differentiation, and manipulation of sex for Neotropical species, with special focus on silversides and other two speciose groups, known as characins (Characiformes) and catfishes (Siluriformes). Currently, there is plenty of information available on chromosomal sex determination systems, which includes both male and female heterogamety with many variations, and sex chromosomes evolution at the macro chromosomal level. However, there is hitherto a blank in information at micro, gene/molecule levels and in research related to the effects of environmental cues on sex determination; most of reported studies are limited to silversides and guppies. In view of such a high diversity, it is critically necessary to establish key model species for relevant Neotropical fish taxa and also multi-disciplinary research groups in order to uncover the main patterns and trends that dictate the mechanisms of sex determination and gonadal differentiation in this icthyofauna. By increasing our knowledge on sex determination/differentiation with the identification of sex chromosome-linked markers or sex-determining genes, characterization of the onset timing of morphological gonadal differentiation, and determination of the environmental-hormonal labile period of gonadal sex determination in reference species, it will be possible to use those information as guidelines for application in other related groups. Overall, the strategic advance in this research field will be crucial for the development of biotechnological tools for aquaculture industry and for conservation of fish fauna from the Neotropical Region.
Genetics-based methods for agricultural insect pest management
18687N. Alphey and M. B. Bonsall, Agricultural and Forest Entomology, 20:131-140. 2018-05-01 13:30:37.
Abstract The sterile insect technique is an area-wide pest control method that reduces agricultural pest populations by releasing mass-reared sterile insects, which then compete for mates with wild insects. Contemporary genetics-based technologies use insects that are homozygous for a repressible dominant lethal genetic construct rather than being sterilized by irradiation. Engineered strains of agricultural pest species, including moths such as the diamondback moth Plutella xylostella and fruit flies such as the Mediterranean fruit fly Ceratitis capitata, have been developed with lethality that only operates on females. Transgenic crops expressing insecticidal toxins are widely used; the economic benefits of these crops would be lost if toxin resistance spread through the pest population. The primary resistance management method is a high-dose/refuge strategy, requiring toxin-free crops as refuges near the insecticidal crops, as well as toxin doses sufficiently high to kill wild-type insects and insects heterozygous for a resistance allele. Mass-release of toxin-sensitive engineered males (carrying female-lethal genes), as well as suppressing populations, could substantially delay or reverse the spread of resistance. These transgenic insect technologies could form an effective resistance management strategy. We outline some policy considerations for taking genetic insect control systems through to field implementation.
Agricultural production: assessment of the potential use of Cas9-mediated gene drive systems for agricultural pest control
13796M. J. Scott, F. Gould, M. Lorenzen, N. Grubbs, O. Edwards and D. O’Brochta, Journal of Responsible Innovation, 5:S98-S120. 2018-01-24 15:43:20.
To highlight how gene drives could be useful for control of agricultural insect pests, we selected species that are pests of animals (New World screwworm), plants (spotted wing Drosophila, diamondback moth, Bemisia tabaci whitefly), or stored grains (red flour beetle). We provide examples of gene drives that target specific genes including female-essential genes. Further, we discuss issues related to containment in the laboratory and eventual field testing of strains harboring a Cas9-mediated gene drive system.
Production of YY Supermale and XY Physiological Female Common Carp for Potential Eradication of this Invasive Species
11508M. Y. Jiang, X. X. Wu, K. X. Chen, H. R. Luo, W. Yu, S. T. Jia, Y. M. Li, Y. F. Wang, P. H. Yang, Z. Y. Zhu and W. Hu, Journal of the World Aquaculture Society, 49:315-327. 2018-01-03 15:22:53.
The common carp, Cyprinus carpio, is the third most cultivated freshwater species worldwide, but is also considered an invasive species. The Trojan Y chromosome strategy is one of the most promising methods to eradicate this invasive species. However, obtaining fertile YY supermale (MYY) and YY physiological female (FYY) common carp was thought to be very difficult. The present study focused on the production of androgenetic MYY and XY physiological female (FXY) common carp. We first optimized the conditions for artificially induced androgenesis. The results indicated that the optimum ultraviolet (UV) exposure time was 4min at an irradiation distance of 26cm and the optimum initiation time with heat shock (40 +/- 0.5C for 2min) was 30min after fertilization. Then, we produced androgenetic MYY Yellow River carp with only paternal inheritance, which were viable and identified by paternity testing and test crossing. Finally, we successfully produced FXY Yellow River carp by feeding 60-d-old MXY with commercially available feed mixed with 17-estradiol (200mg/kg) and Flutamide (200mg/kg) for 3mo. In conclusion, by combining artificially induced androgenesis with an artificially induced sex reversal technique, we could cost-effectively produce MYY and FXY common carp.
Trojan Females and Judas Goats: Evolutionary Traps as Tools in Wildlife Management
13743B. A. Robertson, R. S. Ostfeld and F. Keesing, Bioscience, 67:982-993. 2017-11-01 19:42:43.
Here, we bring together science from the pest-control, eco-evolutionary, and conservation communities to outline how evolutionary traps can be repurposed to eliminate or control pest species. We highlight case studies and devise strategies for the selection of appropriate cues to manipulate, traits to target, and mechanisms to use in setting evolutionary traps that will most rapidly reduce animal abundance while preventing evolutionary escape. We find that evolutionary traps are demonstrably effective and unique tools with high target-species specificity that are deployable in concert with more traditional approaches.
The potential for the use of gene drives for pest control in New Zealand: a perspective
14253P. K. Dearden, N. J. Gemmell, O. R. Mercier, P. J. Lester, M. J. Scott, R. D. Newcomb, T. R. Buckley, J. M. E. Jacobs, S. G. Goldson and D. R. Penman, Journal of the Royal Society of New Zealand, 48:225-244. 2017-10-25 14:20:45.
Here we describe the current state of gene drive technologies and present a series of examples to examine the potential benefits and problems arising from gene drive approaches for pest control in New Zealand.
The sterile male release approach as a method to control invasive amphibian populations: a preliminary study on Lithobates catesbeianus
13727S. Descamps and A. De Vocht, Management of Biological Invasions, 8:361-370. 2017-09-14 18:55:55.
Widespread populations of the invasive species Lithobates catesbeianus (American bullfrog) are present in different parts of the world and are difficult to control. This study investigated the possibility to sterilize male individuals of this species in order to use the sterile male release technique in controlling these invasive populations.
The optimal implementation of the Trojan Y chromosome eradication strategy of invasive species
11510M. R. Kelly and X. Y. Wang, Journal of Biological Systems, 25:399-418. 2017-08-02 15:25:17.
Invasive aquatic species continue to be a persistent problem around the world. The Trojan Y Chromosome (TYC) eradication strategy has recently been developed to help fight the problem in aquatic systems by targeting only the invasive species, sparing native marine stock. It involves rearing genetically modified samples of the invasive species and introducing them into the environment to alter the sex ratio of the invasive population. The paper is devoted to finding the optimal implementation of the TYC eradication strategy of an invasive species as well as a modified, potentially more cost-effective strategy. The modified TYC strategy (MTYC) eliminates one round of exposure to sex hormones compared to the TYC strategy. After introducing both strategies, the optimal control problems for each are formulated. The two strategies are compared through numerical simulations. Our results illustrate that the MTYC strategy, with lower implementation costs, is a better strategy option when trying to minimize the overall effective cost in most scenarios.
Illinois study advances possibility of genetic control for major agricultural weeds
11589L. Quinn, ACES News, 2017-07-17 15:35:43.
Waterhemp and Palmer amaranth, two aggressive weeds that threaten the food supply in North America, are increasingly hard to kill with commercially available herbicides. A novel approach known as genetic control could one day reduce the need for these chemicals. Now, scientists are one step closer.
A secret weapon against Zika and other mosquito-borne diseases
6372Nina Federoff, TEDxMidAtlantic, 2017-07-15 15:37:47.
Where did Zika come from, and what can we do about it? Molecular biologist Nina Fedoroff takes us around the world to understand Zika's origins and how it spread, proposing a controversial way to stop the virus -- and other deadly diseases -- by preventing infected mosquitoes from multiplying.
What’s the story with genetic pest management (GPM)?
11584K. Guthrie, Predator Free NZ, 2017-07-13 15:30:50.
Breakthrough genetic technologies are likely to play a key role in achieving a predator-free future. But it’s important that we understand what the various technologies are now – as they’re being developed – not when they’re about to be implemented. We need to debate the issues and become as informed as possible; to know if there are risks involved in particular techniques and what safeguards will be in place. We need to be able to make informed choices, once such choices become possible. Not all genetic techniques, for example, involve ‘genetic engineering’.
Current vector control challenges in the fight against malaria
16269G. Benelli and J. C. Beier, Acta Tropica, 174:91-96. 2017-07-07 16:47:31.
The majority of National Malaria Control Programs in Africa still rely on indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs). These methods reduce malaria incidence but generally have little impact on malaria prevalence. In addition to outdoor transmission, growing levels of insecticide resistance in targeted vectors threaten the efficacy of LLINs and IRS.
Trends in the development of mammalian pest control technology in New Zealand
13735C. T. Eason, L. Shapiro, S. Ogilvie, C. King and M. Clout, New Zealand Journal of Zoology, 44:267-304. 2017-06-19 19:31:49.
The use of new toxins with advantages in specific settings should be complemented by improvements in resetting trap technology, barrier approaches, and novel biocontrol and genetic concepts. Sodium fluoroacetate (1080) and other important tools have been retained; we have the ingredients for transformational change, and new tools are emerging from a research and development pipeline. However, there has been limited practical experience with emerging technologies compared with traditional or 1080 baits.
SCIENTIFIC OPINION: In response to the referral of 12 October 2015 concerning use of genetically modified mosquitoes for vector control
16065High Council for Biotechnology, High Council for Biotechnology (France), 2017-05-31 13:46:03.
The Scientific Committee’s opinion describes emerging vector control techniques using GM mosquitoes, the current state of research into and development of these techniques and the outcomes of initial experiments worldwide. To date, only one technique has been developed to an operational level: Oxitec’s RIDL technique, which sets out to reduce a mosquito population by repeated mass releases of sterilising transgenic males. Two other techniques at an earlier stage of research and development are based on gene drive, seeking to spread a genetic trait in a wild population, either to make the mosquitoes incapable of transmitting pathogens (gene drive for population modification) or to eliminate the population by spreading sterility (gene drive for population elimination).
Area-wide Integrated Pest Management
13603Food and Agriculture Organization of the United Nations (FAO), International Atomic Energy Agency, 2017-05-22 13:34:46.
Throughout history, people have had to fight insect pests to reduce diseases, minimize food losses, protect agricultural trade or simply to avoid the nuisance of stinging, biting and buzzing bugs. Insect pest control is usually implemented locally in individual fields or properties. These uncoordinated efforts often prove inefficient since they only suppress a proportion of the targeted pest population. Pests from nearby untreated areas remain unscathed and can re-enter the treated areas, the damage continues, and people have little choice but to apply the control measures again and again to protect their livelihoods. Area-wide pest management provides a more cost-effective and sustainable approach by proactively targeting entire pest populations. In this way, pest populations can be contained at low levels for longer periods and pest management methods can be integrated that are less reliant on pesticides and that better address ecological and environmental concerns.
Towards the genetic control of invasive species
4047Harvey-Samuel, TA, T.; Alphey, L., Biological Invasions, 19:1683-1703. 2017-01-05 00:00:00.
Invasive species remain one of the greatest threats to global biodiversity. Their control would be enhanced through the development of more effective and sustainable pest management strategies. Recently, a novel form of genetic pest management (GPM) has been developed in which the mating behaviour of insect pests is exploited to introduce genetically engineered DNA sequences into wild conspecific populations. These 'transgenes' work in one or more ways to reduce the damage caused by a particular pest, for example reducing its density, or its ability to vector disease. Although currently being developed for use against economically important insect pests, these technologies would be highly appropriate for application against invasive species that threaten biodiversity. Importantly, these technologies have begun to advance in scope beyond insects to vertebrates, which include some of the world's worst invasives. Here we review the current state of this rapidly progressing field and, using an established set of eradication criteria, discuss the characteristics which make GPM technologies suitable for application against invasive pests.
Concept and history of genetic control
6014Scott, M. J. and Benedict, M. Q., Genetic Control of Malaria and Dengue, 2:31-54. 2016-12-30 20:16:45.
Genetic control of insects is an established method, mainly for insects that are important crop and veterinary pests such as medflies and screwworm. Efforts to use the same technologies against insects of medical importance, especially mosquitoes, have had limited success. The successes against mosquitoes have been accomplished using forms of both conventional and modern methods, both of which are promising. In this chapter, we provide highlights of the development of genetic control of agricultural pests and describe how the development of methods against mosquitoes reflects those advances. While admiring successful genetic control programs is motivating, we suggest that much can also be learned from both past successful and failed efforts, as doing so will increase our ability to improve future activities.
Invertebrate Biosecurity Challenges in High-Productivity Grassland: The New Zealand Example
13738S. L. Goldson, B. I. P. Barratt and K. F. Armstrong, Frontiers in Plant Science, 7. 2016-11-15 19:35:24.
This review explores the unique challenges faced by pasture biosecurity and what may be done to confront existing difficulties. While there is no silver bullet, and limited opportunity pre and at for improving pasture biosecurity, advancement may include increased and informed vigilance by farmers, pheromone traps and resistant plants to slow invasion. Increasingly, there is also the potential for more use of improved population dispersal models and surveillance strategies including unmanned aerial vehicles, as well as emerging techniques to determine invasive pest genomes and their geographical origins.
Mitonuclear interactions, mtDNA-mediated thermal plasticity, and implications for the Trojan Female Technique for pest control
13745J. N. Wolff, D. M. Tompkins, N. J. Gemmell and D. K. Dowling, Scientific Reports, 6. 2016-07-21 19:45:17.
Here we test whether the male-sterilizing effects previously associated with the mt: Cyt-b mutation are consistent across three thermal and three nuclear genomic contexts. The effects of this mutation were indeed moderated by the nuclear background and thermal environment, but crucially the fertility of males carrying the mutation was invariably reduced relative to controls. This mutation thus constitutes a promising candidate for the further development of the TFT.
Genetically Modified Mosquitoes Probably Headed to Florida Keys to Fight Zika
23519T. Elfrink, Miami New Times, 2016-04-11 05:12:57.
The bad news: Zika is coming to Florida. This past Friday, two new cases of the virus linked to serious birth defects were reported in the state, and scientists believe it could spread rapidly come summer as mosquito populations explode. And we're still a long way away from a vaccine for the virus. The good news: Scientists still might have a way to stop its spread — by releasing a swarm of genetically modified mosquitoes across the Florida Keys. Yes, it sounds like the premise of pulpy Michael Crichton novel that ends with a zombie horde infected with GMO mosquito viruses. But it's looking ever more likely to happen. The U.S. Food and Drug Administration (FDA) has given tentative approval to the plan, and the New York Times published a lengthy op-ed this weekend arguing in favor of the plan. And several new polls show that most of the public supports giving it a sho
Production of a YY Male Brook Trout Broodstock for Potential Eradication of Undesired Brook Trout Populations
11516D. J. Schill, J. A. Heindel, M. R. Campbell, K. A. Meyer and E. Mamer, North American Journal of Aquaculture, 78:72-83. 2015-12-31 15:35:45.
Brook Trout Salvelinus fontinalis introduced outside of their native range often negatively impact native aquatic fauna or provide marginal fisheries and are frequently targeted for manual or piscicide removal in lakes and streams. Unfortunately, complete eradication of exotic Brook Trout populations via these methods is rarely achieved; new approaches are needed. A potential alternative is a Trojan Y Chromosome (TYC) program in which hatchery-produced genetically YY male fish would be regularly released into an undesired population over time, skewing the population towards 100% males, theoretically resulting in wild population extirpation. We developed two genetic sex markers for Brook Trout and employed juvenile sex reversal methods commonly used in commercial aquaculture to develop a YY broodstock that can produce offspring for possible future use as biological control agents. Our search for genetic sex markers proved successful, with genotypic sex determination for two assays matching the observed phenotype for 90 out of 90 individuals. In the first phase of the program, estradiol-infused feed readily feminized genetic XY males into neofemales (FXY fish) at a high rate (99.6%; n = 224). Survival of progeny from such egg-laying FXY fish averaged 88% to eye-up and 91% from eye-up to ponding, values similar to untreated Brook Trout reared at the same facility. In the second program phase, we cultured both sperm-and egg-producing supermales (YY fish), a vital step towards development of TYC technology on a large aquaculture scale. Results showed that, in the hatchery, estradiol treatment does not reduce Brook Trout growth. This study demonstrates that hatchery production of a YY Brook Trout broodstock is feasible, modest in cost (less than US$10,000), and can be completed in 4 years. Although several hurdles remain before a full-scale stocking program could occur, we believe that future work on the TYC strategy for Brook Trout is warranted.
Science and Technology Committee Genetically Modified Insects
16058UK Parliament, UK Parliament, 2015-12-17 21:18:14.
The UK is a world leader in the development of this technology. The European Union’s regulatory process, however, is likely to hold back progress. There is a moral duty to test the potential of the technology. We therefore support further research and call for action to test the efficiency of the EU process via a trial which should also be used to drive public engagement. GM insect technology has already been trialled for dengue transmitting mosquitoes.
Stochastic models for the Trojan Y-Chromosome eradication strategy of an invasive species
11514X. Y. Wang, J. R. Walton and R. D. Parshad, Journal of Biological Dynamics, 10:179-199. 2015-12-16 15:32:37.
The Trojan Y-Chromosome (TYC) strategy, an autocidal genetic bio-control method, has been proposed to eliminate invasive alien species. In this work, we develop a Markov jump process model for this strategy, and we verify that there is a positive probability for wild-type females going extinct within a finite time. Moreover, when sex-reversed Trojan females are introduced at a constant population size, we formulate a stochastic differential equation (SDE) model as an approximation to the proposed Markov jump process model. Using the SDE model, we investigate the probability distribution and expectation of the extinction time of wild-type females by solving Kolmogorov equations associated with these statistics. The results indicate how the probability distribution and expectation of the extinction time are shaped by the initial conditions and the model parameters.
The Trojan Female Technique for pest control: a candidate mitochondrial mutation confers low male fertility across diverse nuclear backgrounds in Drosophila melanogaster
13733D. K. Dowling, D. M. Tompkins and N. J. Gemmell, Evolutionary Applications, 8:8710880. 2015-07-15 19:28:56.
The Trojan Female Technique (TFT) was recently proposed as a prospective approach to biological pest control. However, applicability of the TFT relies on mitochondrial mutations whose male-sterilizing effects are general across nuclear genomic contexts. We test this assumption, expressing the candidate TFT-mutation bearing haplotype alongside a range of nuclear backgrounds and comparing its fertility in males, relative to that of control haplotypes
Ecological and evolutionary applications for environmental sex reversal of fish
11518A. McNair, P. M. Lokman, G. P. Closs and S. Nakagawa, Quarterly Review of Biology, 90:23-44. 2015-03-01 15:38:29.
Environmental sex reversal (ESR), which results in a mismatch between genotypic and phenotypic sex, is well documented in numerous fish species and may be induced by chemical exposure. Historically, research involving piscine ESR has been carried out with a view to improving profitability in aquaculture or to elucidate the processes governing sex determination and sexual differentiation. However, recent studies in evolution and ecology suggest research on ESR now has much wider applications and ramifications. We begin with an overview of ESR in fish and a brief review of the traditional applications thereof We then discuss ESR and its potential demographic consequences in wild populations. Theory even suggests sex-reversed fish may be purposefully released to manipulate population dynamics. We suggest new research directions that may prove fruitful in understanding how ESR at the individual level translates to population-level processes. In the latter portion of the review we focus on evolutionary applications of ESR Sex-reversal studies from the aquaculture literature provide insight in to the evolvability of determinants of sexual phenotype. Additionally, induced sex reversal can provide information about the evolution of sex chromosomes and sex-linked traits. Recently, naturally occurring ESR has been implicated as a mechanism contributing to the evolution of sex chromosomes.
Genetic control of invasive fish: technological options and its role in integrated pest management
4158Thresher, REH, K.; Bax, N. J.; Teem, J.; Benfey, T. J.; Gould, F., Biological Invasions, 16:1201-1216. 2014-01-16 00:00:00.
Genetic options for the control of invasive fishes were recently reviewed and synthesized at a 2010 international symposium, held in Minneapolis/St. Paul, MN, USA. The only option currently available "off-the-shelf'' is triploidy, which can be used to produce sterile males for a release program analogous to those widely and successfully used for biological control of insect pests. However, the Trojan Y and several recombinant options that heritably distort pest population sex ratios are technologically feasible, are at or are close to proof-of-concept stage and are potentially much more effective than sterile male release programs. All genetic options at this stage require prolonged stocking programs to be effective, though gene drive systems are a potential for recombinant approaches. They are also likely to differ in their current degree of social acceptability, with chromosomal approaches (triploidy and Trojan Y) likely to be the most readily acceptable to the public and least likely to require changes in legislative or policy settings to be implemented. Modelling also suggests that the efficacy of any of these genetic techniques is enhanced by, and in turn non-additively enhance, conventional methods of pest fish control.
Regulatory experience and challenges for the release of GM insects
4135Beech, C, Journal Fur Verbraucherschutz Und Lebensmittelsicherheit-Journal of Consumer Protection and Food Safety, 9:S71-S76. 2014-01-13 00:00:00.
Genetically modified (GM) insects are a potentially valuable new tool for the biological control of insect pests of humans, animals and plants. Considerable progress has been made recently in transfer of GM insects from the laboratory to release and evaluation in the environment. As with other new genetic technologies, regulatory agencies have often found it challenging to determine the regulatory regime under which they should be evaluated, and have either adapted existing regulatory frameworks or adopted new ones. No country has legislation specifically for GM insects. However, irrespective of the regulatory regime under which they are evaluated, the purpose of their regulation remains the same; to protect human health and the environment. Consequently there are evaluation themes common to their regulatory scrutiny, which are elucidated here. There have also been some challenges and issues encountered during the risk evaluation for field release of GM insects, and this paper will highlight some of these to assist others when considering policy, regulation and assessment of GM insects. Useful regulatory and policy precedents also exist from the regulation of biological control agents and the global protection of plants from pests under the International Standards for Phytosanitary Measures (ISPM) framework. Where countries do not have existing regulations, these evaluation instruments could have the potential to be adapted to form a suitable framework for the assessment of risk for GM insects. Finally, some considerations for future policy and regulation in this area are discussed.
Global existence and asymptotic behavior of a model for biological control of invasive species via supermale introduction
11530R. D. Parshad, S. Kouachi and J. B. Gutierrez, Communications in Mathematical Sciences, 11:971-992. 2013-06-15 16:00:28.
The purpose of this manuscript is to propose a model for the biological control of invasive species, via introduction of phenotypically modified organisms into a target population. We are inspired by the earlier Trojan Y Chromosome model [J.B. Gutierrez, J.L. Teem, J. Theo. Bio., 241(22), 333-341, 2006]. However, in the current work, we remove the assumption of logistic growth rate, and do not consider the addition of sex-reversed supermales. Also the constant birth and death coefficients, considered earlier, are replaced by functionally dependent ones. In this case the nonlinearities present serious difficulties since they change sign, and the components of the solution are not a priori bounded, in some LP-space for p large, to permit the application of the well known regularizing effect principle. Thus functional methods to deduce the global existence in time, for the system in question, are not applicable. Our techniques are based on the Lyapunov functional method. We prove global existence of solutions, as well as existence of a finite dimensional global attractor, that supports states of extinction. Our analytical finding are in accordance with numerical simulations, which we also present.
Demographic effects on the use of genetic options for the control of mosquitofish, Gambusia holbrooki
11528R. E. Thresher, M. Canning and N. J. Bax, Ecological Applications, 23:801-814. 2013-06-01 15:57:26.
This study tests the sensitivity of genetically based pest control options based on sex ratio distortion to intra-and intersexual aggressive interactions that affect male and female survival and fitness. Data on these interactions and their impacts were gathered for the mosquitofish Gambusia holbrooki (Poeciliidae), a promiscuous species with a strongly male-biased operational sex ratio and well-documented male harassment of females. The experimental design consisted of an orthogonal combination of two population densities and three sex ratios, ranging from strongly male-biased to strongly female-biased, and long-term observations of laboratory populations. Contrary to expectations, the number of males in a population had little evident effect on population demographics. Rather, the density of adult females determined population fecundity (as a result of a stock-recruitment relationship involving females, but not males), constrained male densities (apparently as a result of cannibalism or intersexual aggression), and regulated itself (most likely through effects of intrasexual aggression on female recruitment). The principal effect of males was to constrain their own densities via effects of male-male aggression on adult male mortality rates. Through use of a realistically parameterized genetic/demographic model, we show that of three different genetic options applied to control G. holbrooki, one based on recombinant sex ratio distortion (release of Female Lethal carriers) is marginally more efficient than a sterile male release program, and both outperform an option based on chromosomal sex ratio distortion (Trojan W). Nonlinear dependence of reproductive rate on female density reduces the efficacy of all three approaches. The major effect of intra-and intersexual aggression is mediated through females, whose interactions reduce female numbers and increase the efficacy of a control program based on sex ratio. Socially mediated male mortality has a small impact on control programs due to operational sex ratios that are heavily male-biased. The sensitivity of sex ratio-based control options to social factors will depend on the mating system of the targeted pest, but evidence of widespread density-dependent population regulation suggests that, for most species, the effects of elevated adult mortality (due to intra-and intersexual aggression) on control programs are likely to be slight.
Analysis of the Trojan Y-Chromosome eradication strategy for an invasive species
11524X. Y. Wang, J. R. Walton, R. D. Parshad, K. Storey and M. Boggess, Journal of Mathematical Biology, 68:1731-1756. 2013-05-24 15:52:53.
The Trojan Y-Chromosome (TYC) strategy, an autocidal genetic biocontrol method, has been proposed to eliminate invasive alien species. In this work, we analyze the dynamical system model of the TYC strategy, with the aim of studying the viability of the TYC eradication and control strategy of an invasive species. In particular, because the constant introduction of sex-reversed trojan females for all time is not possible in practice, there arises the question: What happens if this injection is stopped after some time? Can the invasive species recover? To answer that question, we perform a rigorous bifurcation analysis and study the basin of attraction of the recovery state and the extinction state in both the full model and a certain reduced model. In particular, we find a theoretical condition for the eradication strategy to work. Additionally, the consideration of an Allee effect and the possibility of a Turing instability are also studied in this work. Our results show that: (1) with the inclusion of an Allee effect, the number of the invasive females is not required to be very low when the introduction of the sex-reversed trojan females is stopped, and the remaining Trojan Y-Chromosome population is sufficient to induce extinction of the invasive females; (2) incorporating diffusive spatial spread does not produce a Turing instability, which would have suggested that the TYC eradication strategy might be only partially effective, leaving a patchy distribution of the invasive species.
Combining the Trojan Y chromosome and daughterless carp eradication strategies
11522J. L. Teem and J. B. Gutierrez, Biological Invasions, 16:1231-1240. 2013-05-17 15:50:22.
The Trojan Y chromosome (TYC) strategy and the daughterless carp (DC) strategy represent two autocidal genetic biocontrol methods for eliminating invasive fish by changing the sex ratio of the population. Each strategy is designed to reduce the number of females in a target population, ultimately leading to local extinction of the population. In the DC approach, the proportion of males in the population is increased as a result of introducing an autocidal fish containing a transgenic aromatase gene insertion into multiple autosome sites. In the TYC approach, matings of an autocidal fish containing two Y sex chromosomes results in an increased proportion of males in the population. A mathematical model based upon coupled ordinary differential equations was constructed to observe the effect of an autocidal fish with the combined genetic features of both strategies (TYCDC) on a target population. The model incorporated a fitness parameter associated with fish bearing aromatase inhibitor genes and for fish bearing two Y chromosomes. Under conditions where the fitness penalty of the autocidal fish was negligible, modeling results showed that a combined strategy produced a modest reduction in the time required for female eradication, and that fewer autocidal fish were required to achieve extinction. However, increasing the fitness penalty associated with the autocidal fish neutralized the benefits of the TYCDC strategy, and suggested that the effort and expense of a combined strategy may not be warranted if the fitness cost of the TYCDC autocidal fish is significant.
A comparison of the Trojan Y Chromosome and daughterless carp eradication strategies
11520J. L. Teem, J. B. Gutierrez and R. D. Parshad, 16, 16:1217-1230. 2013-05-08 15:46:59.
Two autocidal genetic biocontrol methods have been proposed as a means to eliminate invasive fish by changing the sex ratio of the population: the Trojan Y Chromosome (TYC) strategy and the Daughterless Carp (DC) strategy. Both strategies were modeled using ordinary differential equations that allow the kinetics of female decline to be assessed under identical modeling conditions. When compared directly in an ordinary differential equation (ODE) model, the TYC strategy was found to result in female extinction more rapidly than a DC strategy (in each of three models tested in which the Daughterless autocidal fish contained an aromatase inhibitor gene in either two or eight copies). The TYC strategy additionally required the introduction of fewer autocidal fish to the target population to achieve local extinction of females as compared to the DC approach. The results suggest that the relatively lower efficiency of female reduction associated with the DC approach is a consequence of a greater capacity to produce females and also a reduced capacity to produce males as compared to the TYC system.
Existence of global attractor for the Trojan Y Chromosome model
11534X. P. Zhao, B. Liu and N. Duan, Electronic Journal of Qualitative Theory of Differential Equations, 2011-07-11 17:09:12.
This paper is concerned with the long time behavior of solution for the equation derived by the Trojan Y Chromosome (TYC) model with spatial spread. Based on the regularity estimates for the semigroups and the classical existence theorem of global attractors, we prove that this equations possesses a global attractor in H-k(Omega)(4) (k >= 0) space.
A Theoretical Strategy for Eradication of Asian Carps Using a Trojan Y Chromosome to Shift the Sex Ratio of the Population
11538J.L. teem and J.B. Gutierrez, Invasive Asian Carps in North America, 74:227-238. 2011-06-01 17:13:22.
The directed extinction of an exotic fish population is proposed using a genetic approach to drastically reduce the ratio of females to males within the population. In the proposed strategy, sex-reversed female fish containing two Y chromosomes (Fyy) are introduced into a normal fish population. The frequencies of each of the four expected genotypes of fish in the simulated population (Fxx, Fyy, Mxy, and Myy) were modeled with a set of coupled ordinary differential equations. The equations take into account birth rate, death rate, and a fixed carrying capacity of the system. Using computer-generated simulations, it was determined that the continuous introduction of a relatively small proportion of Fyy females to the normal population leads to extinction of the exotic fish over time. The proposed eradication strategy is relevant to fish species with an XY sex-determination system that tolerate a YY genotype. Published literature suggests that Asian carps are likely to fulfill these criteria. However, technical barriers associated with sex reversal in Asian carps presently exist and must be overcome before implementation of a YY eradication strategy for Asian carps can be considered in practice. An idealized theoretical model for the eradication of Asian carps is thus presented.
Analysis of the Trojan Y chromosome model for eradication of invasive species in a dendritic riverine system
11532J. B. Gutierrez, M. K. Hurdal, R. D. Parshad and J. L. Teem, Journal of Mathematical Biology, 64:319-340. 2011-03-04 17:07:15.
The use of Trojan Y chromosomes has been proposed as a genetic strategy for the eradication of invasive species. The strategy is particularly relevant to invasive fish species that have XY sex determination system and are amenable to sex-reversal. In this paper we study the dynamics of an invasive fish population occupying a dendritic domain in which Trojan individuals bearing multiple Y chromosomes have been released as a means of eradication. We demonstrate the existence of a bounded absorbing set that represents extinction of the invasive species irrespective of the dendritic configuration. The method of analysis used to obtain global estimates could be applied to other population problems and other geometries.
On the Well Posedness and Refined Estimates for the Global Attractor of the TYC Model
11541R. D. Parshad and J. B. Gutierrez, Boundary Value Problems, 2010-11-22 17:23:35.
The Trojan Y Chromosome strategy (TYC) is a theoretical method for eradication of invasive species. It requires constant introduction of artificial individuals into a target population, causing a shift in the sex ratio that ultimately leads to local extinction. In this work we demonstrate the existence of a unique weak solution to the infinite dimensional TYC system. Furthermore, we obtain improved estimates on the upper bounds for the Hausdorff and fractal dimensions of the global attractor of the TYC system, via the use of weighted Sobolev spaces. These results confirm that the TYC eradication strategy is a sound theoretical method of eradication of invasive species in a spatial setting. It also provides a solid ground for experiments in silico and validates the use of the TYC strategy in vivo.
Progress and prospects for the use of genetically modified mosquitoes to inhibit disease transmission
16052A. A. James, J. D. Mumford, S. L. James and Y. T. Touré, WHO/TDR, 2010-04-01 20:29:20.
The use of genetically modified mosquitoes (GMMs) for disease control has social, economic and ethical implications, so it is important that the World Health Organization (WHO) and its partners provide guidance to countries on these issues. In collaboration with the Foundation for the National Institutes of Health (FNIH), TDR has developed a series of planning meetings on Progress and prospects for the use of genetically modified mosquitoes to inhibit disease transmission. These technical and public consultations will focus on current status and planning for future development.
On the global attractor of the Trojan Y chromosome model.
11536R. D. Parshad and J. B. Gutierrez, Communications on Pure and Applied Analysis, 10:339-359. 2010-01-01 17:11:02.
We consider the Trojan Y Chromosome (TYC) model for eradication of invasive species in population dynamics. We present global estimates for the TYC system in a spatial domain. In this work we prove the existence of a global attractor for the system. We derive uniform estimates to tackle the question of asymptotic compactness of the semi-group for the TYC model in H(2)(Omega). This along with the existence of a bounded absorbing set, which we also derive, demonstrates the existence of a global attractor for the TYC model. The present analysis reveals that extinction of an invasive species is always possible to achieve irrespective of geometric considerations of the domain. This result is valid for TYC systems in which advection is negligible. This theoretical work lays the foundation for experimental studies of the application of the TYC eradication strategy in spatial ecology, since the outcome is in principle guaranteed.
Genetic control of invasive plants species using selfish genetic elements
13612K. A. Hodgins, L. Rieseberg and S. P. Otto, Evolutionary Applications, 2:555-569. 2009-10-30 13:00:19.
Invasive plants cause substantial environmental damage and economic loss. Here, we explore the possibility that a selfish genetic element found in plants called cytoplasmic male sterility (CMS) could be exploited for weed control. We developed an analytical model and a spatial simulation to assess the use of CMS alleles to manage weed populations.
Use of Genetically Engineered Fruit Fly and Pink Bollworm in APHIS Plant Pest Control Programs: Final Environmental Impact Statement—October 2008
16049USDA/APHIS, USDA/APHIS, 2008-10-01 20:18:57.
The U.S. Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), in cooperation with several States and foreign countries, is proposing further development of genetically engineered fruit fly species and pink bollworm for use in various applications of the sterile insect technique (SIT) applied to agency invasive plant pest control programs. There have been laboratory and confined field studies to test the efficacy of certain genetic engineering applications that could provide benefits to these programs, but these techniques have not been applied in agency eradication actions or preventive release program (PRP) strategies.
The Impact of Dissociation on Transposon-Mediated Disease Control Strategies
23831J. M. Marshall, Genetics, 178:1673-1682. 2008-03-01 23:54:22.
Vector-borne diseases such as malaria and dengue fever continue to be a major health concern through much of the world. The emergence of chloroquine-resistant strains of malaria and insecticide-resistant mosquitoes emphasize the need for novel methods of disease control. Recently, there has been much interest in the use of transposable elements to drive resistance genes into vector populations as a means of disease control. One concern that must be addressed before a release is performed is the potential loss of linkage between a transposable element and a resistance gene. Transposable elements such as P and hobo have been shown to produce internal deletion derivatives at a significant rate, and there is concern that a similar process could lead to loss of the resistance gene from the drive system following a transgenic release. Additionally, transposable elements such as Himar1 have been shown to transpose significantly more frequently when free of exogenous DNA. Here, we show that any transposon-mediated gene drive strategy must have an exceptionally low rate of dissociation if it is to be effective. Additionally, the resistance gene must confer a large selective advantage to the vector to surmount the effects of a moderate dissociation rate and transpositional handicap.
Control of introduced species using Trojan sex chromosomes
11543S. Cotton and C. Wedekind, Trends in Ecology & Evolution, 22:441-443. 2007-07-20 17:25:46.
To control introduced exotic species that have predominantly genetic, but environmentally reversible, sex determination (e.g. many species of fish), Gutierrez and Teem recently modeled the use of carriers of Trojan Y chromosomes - individuals who are phenotypically sex reversed from their genotype. Repeated introduction of YY females into wild populations should produce extreme male-biased sex ratios and eventual elimination of XX females, thus leading to population extinction. Analogous dynamics are expected in systems in which sex determination is influenced by one or a few major genes on autosomes.
Radiation-induced sterility for pupal and adult stages of the malaria mosquito Anopheles arabiensis
25750M. E. H. Helinski, A. G. Parker and B. G. J. Knols, Malaria Journal, 5:10. 2006-05-16 15:23:31.
The optimal dose for male insects to be released in an SIT programme depends on their level of sterility and competitiveness. The use of semi-sterilizing doses to produce more competitive insects is discussed. The most convenient developmental stage for mosquito irradiation on a mass-scale are pupae, but pupal irradiation resulted in a lower insemination rate at the highest dose compared to adult irradiation. On the basis of this study, a suitable dose range that includes semi-sterilizing doses is identified to initiate competitiveness experiments for males irradiated at both developmental stages.
Genetic strategies for controlling mosquito-borne diseases
6191F. Gould, K. Magori and Y. Huang, American Scientist, 94:238. 2006-05-03 19:19:14.
Malaria kills more than a million people each year, primarily children under the age of six. Dengue fever is less deadly, but an outbreak can debilitate millions of people and easily overwhelm doctors and hospitals in tropical cities
A model describing the effect of sex-reversed YY fish in an established wild population: The use of a Trojan Y chromosome to cause extinction of an introduced exotic species
11545J. B. Gutierrez and J. L. Teem, Journal of Theoretical Biology, 241:333-341. 2006-01-06 17:28:07.
A novel means of inducing extinction of an exotic fish population is proposed using a genetic approach to shift the ratio of male to females within a population. In the proposed strategy, sex-reversed fish containing two Y chromosomes are introduced into a normal fish population. These YY fish result in the production of a disproportionate number of male fish in subsequent generations. Mathematical modeling of the system following introduction of YY fish at a constant rate reveals that female fish decline in numbers over time, leading to eventual extinction of the population. (c) 2005 Elsevier Ltd. All rights reserved.
An Anopheles transgenic sexing strain for vector control
16647F. Catteruccia, J. P. Benton and A. Crisanti, Nature Biotechnology, 23:1414-1417. 2005-10-09 20:04:20.
Here we report on the development of transgenic sexing lines for the mosquito Anopheles stephensi, the principal vector of human malaria in Asia. Male mosquitoes, expressing enhanced green fluorescent protein (EGFP) under the control of the beta 2-tubulin promoter, are identified by their fluorescent gonads in as early as their 3(rd) instar larval stage, and can be efficiently separated from females using both manual methods and automated sorting machines. Importantly, beta 2-EGFP males are not impaired in their mating ability and viable fluorescent spermatozoa are also detected in spermathecae of wild-type females mated with transgenic males. The transgenic mosquito lines described here combine most of the features desired and required for a safe application of transgenic methodologies to malariacontrol programs.
TSETSE GENETICS: Contributions to Biology, Systematics, and Control of Tsetse Flies
26199R. H. Gooding and E. S. Krafsur, Annual Review of Entomology, 50:101-123. 2005-01-01 14:04:26.
Tsetse flies (Diptera: Glossinidae) constitute a small, ancient taxon of exclusively hematophagous insects that reproduce slowly and viviparously. Because tsetse flies are the only vectors of pathogenic African trypanosomes, they are a potent and constant threat to humans and livestock over much of sub-Saharan Africa. Despite their low fecundity, tsetse flies demonstrate great resilience, which makes population suppression expensive, transient, and beyond the capacities of private and public sectors to accomplish, except over small areas. Nevertheless, control measures that include genetic methods are under consideration at national and supranational levels. There is a pressing need for sufficient laboratory cultures of tsetse flies and financial support to carry out genetic research. Here we review tsetse genetics from organismal and population points of view and identify some research needs.
Malaria Control with Genetically Manipulated Insect Vectors
16035L. Alphey, C. B. Beard, P. Billingsley, M. Coetzee, A. Crisanti, C. Curtis, P. Eggleston, C. Godfray, J. Hemingway, M. Jacobs-Lorena, A. A. James, F. C. Kafatos, L. G. Mukwaya, M. Paton, J. R. Powell, W. Schneider, T. W. Scott, B. Sina, R. Sinden, S. Sink, Science, 298:119. 2002-10-04 19:49:32.
At a recent workshop, experts discussed the benefits, risks, and research priorities associated with using genetically manipulated insects in the control of vector-borne diseases.
Sterility introduced by release of genetically altered males to a domestic population of Aedes aegypti at the Kenya coast
25875P. T. McDonald, W. Hausermann and N. Lorimer, Am J Trop Med Hyg, 26:553-61. 1977-05-06 07:09:31.
The release of males heterozygous for one or two sex-linked translocations was effective in introducing a high level of sterility into a domestic population of Aedes aegypti at a Rabai village. The effect of the releases continued for several weeks after the release period. Male mosquitoes, Aedes aegypti, were released at the Kenya coast to test the effectiveness of laboratory engineered mosquitoes in introducing a genetic mechanism and the ability of the mechanism to establish itself under field conditions. A triplicate of Rabai villages was selected for the experiment. In the 1st village nottreatment was made. In the 2nd village the domestic water containers were cleaned twice a week to remove larvae and pupae. Translocation males were released in the 3rd village. A mixture of 2 types of males was introduced: the single heteroxygote male selected from 78 translocations induced by irradiation in the African strains, and the double heterozygote male. Genetic analysis of the content of release samples determined quality control of released males. Fertility was also determined with females of a strain collected at Chibarani before releases began. Hatchability of eggs in all villages was counted to assay sterility in all villages. Before the releases population fluctuations in the 3 villages were monitored for 20 weeks. The release mixture had a fertility of 37% and the single heterozygote of 50%. A daily survival rate of .63 was shown for the dusted release males. There was close agreement between the monitoring for sterility for both the egg collections and the oviposition of the LB catch females. The sterility introduced into the Chibarani population was extensive.
Genetic control of insect populations: I. Cage studies of chromosome replacement by compound autosomes in Drosophila melanogaste
6297M. Fitz-Earle, D. G. Holm and D. T. Suzuki, Genetics, 74:461-475. 1973-07-08 19:53:27.
A genetic method for insect control was evaluated using the test organism, Drosophila melanogaster. The technique involved the displacement under a system of continuous reproduction, of standard strains by those carrying compound autosomes. The eradication of the replacements could subsequently be achieved through the use of temperature-sensitive lethal mutations.—While certain compound autosome strains failed to displace standards in population cages, even at the initial release ratio of 25:1, others were highly successful. Indeed, for some strains when the ratio of compounds to standards was as low as 9:1, the population rapidly went to fixation in favor of the compound line.—Hatchability was found to be an insufficient index of fitness to estimate the initial ratios of compounds to standards that would guarantee fixation of the former. Differences in other fitness components, such as development time, were detected that could seriously modify displacement, especially with continuous overlapping generations. The importance of examining the fitness of various compound lines and selecting the most competitive in cages, prior to field tests, cannot be overemphasized.
Changing population structure through the use of compound chromosomes
6295D. Childress, Genetics, 72:183-186. 1972-09-08 19:50:49.
Theoretical calculations and population cage data are presented to illustrate the use of compound chromosomes to change the genetic structure of insect populations.
Chromosome rearrangements for the control of insect pests
6293G. G. Foster, M. J. Whitten, T. Prout and R. Gill, Science, 176:875-880. 1972-05-26 19:48:27.
Over several years some biologists have been interested in the possibilities of employing genetic techniques in the control of insect pests. One idea has been to introduce in the natural population genotypes which could subsequently facilitate control, or which might render the pest innocuous. An- other idea that followed from the success of the .'sterile male" technique was to release genotypes with chromosomal aberrations whose subsequent segregation would result in sterility effects damaging to the population. Whitten (I) suggested combining these two ideas in one operation: in its simplest form the desired genotype would be obtained by incorporating the required genes in a chromosomal translocation. This would then be released as a homozygote in excess of the intrinsic unstable equilibrium which would result from the semisterility of the translocation heterozygote. The translocation producing the desired genotype would then autonomously become fixed while the genotype at the same time would produce sterile progeny in the early stages of the process. Thus we have the concept of a genetic transporting mechanism and a desired genotype to be transported, with the additional benefit of a transport device that might itself have transient damaging effects.
Applications of genetic technology to mosquito rearing
6098G. B. Craig, Bulletin of the World Health Organization, 29:89-97. 1963-01-02 16:40:36.
Since the development of insecticide-resistance and the consequent partial failure of the chemical approach to the control of disease vectors, interest in the biological approach has re-awakened. An aspect of the latter approach that is of great current interest is " autocidal control "-that is, the use of insects for their own destruction. This paper discusses the various ways in which genetic mechanisms can be used to bring about the destruction of harmful insects, with special reference to those of medical importance. The author considers that the prospects for the genetic control of vector species are good, but stresses that before genetic methods can be applied on a field scale certain requirements must be met. For example, genetic technology must be expanded, a firm background of genetic knowledge of vector species must be built up, a great deal more information about vector ecology, particularly population dynamics, must be acquired, and techniques for the mass production of vector insects under controlled conditions must be developed.
Screw-worm control through release of sterilized flies
6107A. H. Baumhover, A. J. Graham, B. A. Bitter, D. E. Hopkins, W. D. New, F. H. Dudley and R. C. Bushland, Journal of Economic Entomology, 48:462-466. 1955-08-03 17:00:44.
Screw-worms, Callitroga hominivorax (Cqrl.), did not exist in the southeastern United States until about 20 years ago, and it is probable that, if the present infestation could be eradicated, the area might be kept free of infestation through inspection of livestock shipments originating in infested areas
Possibilities of Insect Control or Eradication Through the Use of Sexually Sterile Males
6006E. F. Knipling, Journal of Economic Entomology, 48:459-462. 1955-08-01 19:58:21.
The purpose of this paper is to consider the possibility of controlling insects by releasing sexually sterile males among the existing natural population. The principles involved will be described and the potentialities as well as the limitations of the method as we know them at present, will be discussed.
Eradication of screw-worms through release of sterilized males
6091R. C. Bushland, A. W. Lindquist and E. F. Knipling, Science, 122:287-288. 1955-01-02 14:50:36.
Although the sterilizing effect of ionizing radiations has been known for years, it is only recently that entomologists have attempted to take advantage of the phenomenon for insect control. Knipling (1) has theorized on the effects of releasing sterilized males among a normal insect population. In 1947, on a visit to the Kerrville, Tex., laboratory, he proposed investigations on the mating habits of the screw-worm, Callitroga hominivorax (Cqrl.), and experiments with sterilized males. In such experiments Bushland and Hopkins (2) found that screw-worms were easily sterilized by exposing pupae to x-rays or gamma rays. They showed that under laboratory conditions male screw-worms mated repeatedly but fe males only once. If a female mated with a sterilized male it did not mate again and laid eggs that did not hatch. When mixed populations of normal and sterilized insects were observed in cages, the sterilized and normal males competed about equally for mates.
On the possibility of a new method for the control of insect pests.
6157A. S. Serebrovskii, Zoologicheskiĭ zhurnal, 19:618-630 (in Russian). 1940-01-03 16:43:28.
ON THE POSSIBILITY OF A NEW METHOD FOR THE CONTROL OF INSECT PESTS. The new principle of insect control consists in disturbing the propagation of the pest population by means of translocations. It is well known that individuals heterozygous for some translocations usually form a portion of aneuploid gametes and give a more or less inviable aneuploid progeny. On releasing, therefore, a sufficient number of individuals with a chromosome set altered by. translocations into a wild population (with allogamous propagation), there will arise heterozygotes for translocations yielding a certain percentage of inviable offspring. Crosses inside this population will be similar to those between species with resulting sterility of hybrids. The theoretical analysis reveals that if a wild population is mixed in proportion 1:1 with some race containing only one translocation viable in homozygous condition and giving in heterozygotes 50% of aneuploid gametes, the reproduction of the population will be reduced by 43%. If several races with different allelic translocations are released the reduction of reproduction in the population can reach 75%, and if races with 4-5 independent translocations are used the reduction can attain 95%-99% and even more. A population consisting of races with different translocations cannot remain in balance. Those types of chromosomes which happened to be in minority are subjected to elimination. Yet this process of elimination will go on during many generations and thus the disturbance of reproduction will be protracted. By an additional releasing of eliminating race, this disturbance can be maintained permanently. Diverse variants of this method are possible, depending upon the biology and economic importance of injurious insects, the cost of breeding translocated races in laboratories, the difficulties of obtaining viable translocations, etc. It is possible, for instance, to release only males, a method in which there is evidently no danger at all. The present investigation is a purely theoretical one. For the purpose of verifying experimentally this idea work has been started with Musca domestica and Calandra granaria - two insects widely differing in their cytogenetics, ecology and the kind of damage caused.
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