Keywords: Aedes
Modelling Aedes albopictus management, incorporating immigration and bi-directional Wolbachia interactions
35520Ryan, M., Mendiolar, M., Pagendam, D. et al., J Pest Sci, 99. 2026-03-10 09:16:51.
Aedes albopictus mosquitoes are competent vectors for the spread of at least 24 different arboviruses, including dengue, Ross River, and Japanese encephalitis viruses. However, they remain less studied than their more urban cousins, Aedes aegypti. We model an incompatible insect technique (IIT) strategy for mosquito control, with bi-directional incompatibility between two strains of Wolbachia (wAlbA/wAlbB ARwP) and age-based cytoplasmic incompatibility decay in a well-mixed population. We include mosquito immigration to explore potential reversibility, an important consideration in bi-directional IIT control programs. We also explore the establishment probability after female contamination of an artificially-infected Wolbachia mosquito strain, consider the suppression dynamics and probability of mosquito management success for different release strategies, and determine a corresponding cost proxy for release (numbers of mosquitoes released). We found an establishment probability threshold of 40% in the absence of mating preferences, though this threshold needs validation in future field and laboratory experiments. We found differences in suppression success between release cessation and 6 months later for different immigration rates. There are similar short-term costs with differences in medium- and longer-term costs between release strategies. Our model suggests bi-directional IIT control programs are reversible with low amounts of wild-type immigration. This work demonstrates opportunities to optimise the suppression of these medically important mosquitoes.
Mark–release–recapture study of irradiated male Aedes albopictus under stressful field conditions
35492Qingdeng Feng, Ming Li, Jeremy Bouyer, et al., Pest Management Science, 2026-03-09 10:33:54.
The sterile insect technique (SIT) suppresses mosquito populations by releasing sterile males. Its success mainly depends on the performance of sterile males. Mark–Release–Recapture (MRR) experiments are used to evaluate male performance in the field, yet most previous experiments were conducted under mild conditions (e.g. 25–28 °C) in which mosquitoes could easily adapt. Male mosquito performance under stressful field conditions remains poorly understood. This study evaluated the field performance of irradiated Aedes albopictus males under high-temperature conditions (>30 °C in average) in southern China, Foshan City, located in a sub-tropical area. Two MRR experiments were conducted in a 5-ha village during July–August of 2023 and 2024. Lifespan and dispersal of postreleased males were examined using BG-Sentinel mosquito traps, human landing catches, and ovitraps. A total of 54 546 and 58 440 sterile males were released in 2023 and 2024, respectively, with recapture rates of 8.53% and 5.64%. The mean dispersal distances ranged from 58.88–77.19 m (2023) to 81.82–90.86 m (2024). Daily survival probabilities were 0.15–0.28 in 2023 and 0.45–0.62 in 2024, corresponding to average expected lifespans of 0.53–0.78 days and 1.26–2.13 days, respectively. Estimated wild male densities ranged from 302–986 males ha−1 in 2023 to 416–3785 males ha−1 in 2024. Stressful field conditions severely reduced sterile male survival and dispersal, highlighting the need to optimize release protocols in challenging climates. These findings provide critical baseline data for advancing Ae. albopictus SIT programmes in southern China.
Wolbachia wMel and wAlbB strains differentially impact the vector competence of Aedes aegypti with a Brazilian genetic background for DENV-1 virus
35484Martins, C.B., David, M.R., Couto-Lima, D. et al., Parasites Vectors, 2026-03-05 08:32:23.
Aedes aegypti mosquitoes infected with the endosymbiotic bacterium Wolbachia pipientis have been released as a sustainable strategy to mitigate arbovirus transmission. Among the strains successfully deployed, wMel and wAlbB have shown promising blocking effects against dengue virus (DENV). However, the strength of viral inhibition depends on Wolbachia density within mosquito tissues, the genetic backgrounds of both host and virus, and the viral dose. In this study, we aimed to investigate the vector competence for DENV-1 of Ae. aegypti with Brazilian genetic background infected with wMel or wAlbB. A total of 493 wild and wMel- and wAlbB-infected mosquitoes were orally challenged with low (5 × 104 FFU/mL) and high (5 × 105) titers of DENV-1. Relative Wolbachia density was measured by quantitative polymerase chain reaction (qPCR), and viral infection in mosquito bodies and saliva was assessed by qPCR with reverse transcription (RT-qPCR). Transmission potential was tested through saliva microinjection into susceptible mosquitoes. The infection prevalence and viral loads in mosquito bodies were analyzed at 7, 14, and 21 days post infection (dpi).Both Ae. aegypti groups infected with wMel and wAlbB had reduced (albeit distinct) DENV-1 infection and transmission relative to wild type mosquitoes. wMel-infected mosquitoes exhibited less abundant bacteria in their bodies but a greater degree of DENV-1 inhibition compared with those carrying wAlbB, indicating that DENV-1 blocking is strain specific rather than Wolbachia density-driven. Moreover, we observed that Wolbachia had a protective effect on mosquitoes by decreasing the DENV-1 loads in their bodies, but with a constant presence of virus. Viral transmission rates in the saliva were similar among wild and wMel- and wAlbB-infected mosquitoes at 7 and 14 dpi but lower in wMel and wAlbB mosquitoes at 21 dpi. The similar DENV-1 loads in mosquito bodies over time (7, 14, and 21 dpi) infected with either the wMel or wAlbB strain, regardless of the viral titer of the infectious blood meal, suggest that Wolbachia may have a maximum pathogen-blocking capacity beyond which additional virus suppression cannot be achieved. The viral suppression only after 21 dpi in the saliva raises concerns and warrants further investigation, as females may transmit before Wolbachia blockage becomes effective. While wAlbB may exhibit comparable DENV-1 blocking to wMel, its enhanced thermal tolerance makes it epidemiologically relevant in tropical regions. Continuous monitoring of Wolbachia dynamics and DENV genomic variation in the field remains essential to evaluate long-term effectiveness and detect potential adaptive viral responses.
Evaluation of local larval diets for mass rearing of Aedes aegypti to support sterile insect technique programs in Burkina Faso Get
35466Bouraïma Vincent Séré, Simon P Sawadogo, Prisca S L Paré, et al., Journal of Medical Entomology, 63. 2026-02-16 14:16:30.
Aedes aegypti Linnaeus 1762 is the primary vector of several viruses that cause arboviral diseases. Control strategies, such as SIT, require large-scale mosquito (Diptera: Culicidae) production, which depends critically on larval nutrition. However, the high cost and limited availability of conventional feed components hinder SIT implementation, particularly in resource-limited settings. Faced with this situation, it is imperative to find locally produced food sources. Here, we assessed six locally derived diets for their suitability in mass rearing Aedes aegypti. The diets include: (B) African Clarias gariepinus Burchell 1822 (Siluriformes: Clariidae) dried without additives; (C) Cirina butyrospermi Vuillet 1911 (Lepidoptera: Saturniidae) dried without additives; (D) Glycine max (L.) Merr., 1917 without additives; (E) a 1:1 mixture of Clarias gariepinus and Cirina butyrospermi; (F) a 1:1 mixture of Clarias gariepinus and Glycine max; and a mixture of 50% Clarias gariepinus, (G) 25% Glycine max and 25% Cirina butyrospermi. (A) Commercial fish food formulation (TetraMin® Baby) served as the control. Diets C and D were associated with significantly delayed while diets C, D, and E yielded fewer adults than the control. In contrast, diets B and G provided the most favorable balance of development time, adult emergence, and survival, comparable to the control group. Diets D and F produced the lowest fecundity and hatch rates, whereas diet G generated large, fertile adults. Collectively, these findings indicate that diets B and G are suitable for mass rearing, with diet G emerging as a cost-effective alternative for SIT programs targeting Aedes aegypti in Burkina Faso.
Mathematical modelling of Wolbachia replacement in Aedes aegypti for dengue control: a scoping review
35445Katie Tiley, Laith Yakob, Kathleen O'Reilly, Oliver Brady, Proc Biol Sci, 293. 2026-02-12 17:52:03.
Wolbachia replacement in dengue virus vectors is a promising tool for controlling transmission, and models can explore its potential in novel and complex scenarios. We analyse how research questions in Wolbachia replacement modelling have developed over time and in response to empirical findings. A scoping review was conducted of Wolbachia replacement models. For each study, we extracted research questions, key findings and modelling methodology and thematically categorized research questions. From 726 search results, 115 studies met inclusion criteria. Four themes were identified: identifying key Wolbachia characteristics (n = 61, 53.0%), investigating effects of environmental heterogeneity (n = 21, 18.3%), estimating epidemiological impact (n = 25, 21.7%) and exploring Wolbachia replacement in combination with other arboviral control measures (n = 8, 7.0%). Models identify cytoplasmic incompatibility (CI) and maternal transmission (MT) as key for fixation success. However, less than 20% (n = 6) of studies parameterize CI and MT using empirical sources. Although models agree outbreaks may occur with fixation, few explore epidemiological outcomes of heterogeneous Wolbachia fixation or combined vector control. These findings highlight the need for empirical parameterization and incorporating environmental complexity for models to remain insightful for decision-making. Policymakers would benefit from future models exploring heterogeneous coverage and combined control strategies, given evidence of context-specific outcomes and diverse control tools.
Spatial Dynamics and Sterilization Range of Incompatible Aedes albopictus Males: Advancing Toward an Optimized IIT Approach
35474Lampazzi, E., Virgillito, C., Caputo, B., et al., Tropical Medicine and Infectious Disease, 11. 2026-02-06 18:17:05.
The Incompatible Insect Technique (IIT) is a species-specific, eco-friendly mosquito control method that relies on releasing Wolbachia-infected males, which induce cytoplasmic incompatibility (CI), rendering eggs inviable when mating with wild females. Aiming at optimizing IIT protocols in terms of cost-effectiveness, data on incompatible male dispersal and survival and the distance- and time-related impact of induced sterility are fundamental. This study plans to fill this gap and reports findings from a two-year field trial (2022–2023) at the ENEA-Casaccia Research Center, based on single-spot releases of incompatible Aedes albopictus males (ARwP strain). Male releases were carried out in late September 2022 (~15,000 released males) and the early Ae. albopictus season (at the end of June 2023; ~24,000 released males). Fifty-eight ovitraps were located at a 20–900 m distance from the ARwP release spot and were monitored weekly from May to November to assess egg hatching rates and measure CI effects in relation to both distance and time. Following the 2023 release, samples of adults were collected at increasing distances from the release site and at multiple post-release time points to assess, individually, wild female fertility and ARwP male dispersal and survival using Wolbachia as a genetic marker. Statistical analyses revealed that: (a) the highest reduction in the egg hatching was found within 100 m from the release spot (46.5% and 19.9%, respectively, in 2022 and 2023) but remained significant even at greater distances (29.9% and 7.7% at 300 m, respectively, in 2022 and 2023); (b) accordingly, the highest reduction in the wild female fertility occurred within 100 m from the release spot (47.3%), but similar effects were recognizable up to 600 m; (c) the overflooding ratio of the ARwP males did not significantly differ between 3 and 11 days after the release, with ARwP males remaining active up to 18 days and dispersing as far as 400 m. These results demonstrate the potential of localized, non-inundative IIT trials to furnish clues for the setup of spatially optimized release strategies, especially in scaled-up applications. The study also emphasizes the need for standardized assessment tools and further research regarding environmental and behavioral factors influencing long-term suppression outcomes.
Field implementation of the sterile insect technique against Aedes aegypti in Recife, Brazil: operational challenges and impact of release frequency on vector dynamics
35418Macedo, A.T., Carvalho, D.O., Gomez, M. et al., Infectious Diseases of Poverty, 15. 2026-02-02 16:59:43.
The sterile insect technique (SIT) is an environmentally friendly tool for suppressing Aedes aegypti populations. While promising in controlled settings, its application in large urban environments presents logistical and biological challenges. This trial focused on releasing sterile males, sent from a long-distance production facility to suppress the local mosquito population. Sterile males of Ae. aegypti were mass-reared, irradiated, and transported 712.2 km from a central facility to Recife, Brazil. Releases were performed once (SIT 1 ×) or twice per week (SIT 2 ×). Entomological indices—including eggs/trap per day (ETD), hatch rate, induced sterility, and adult female abundance—were monitored through ovitraps and BG-Sentinel traps. Data were analyzed using generalized linear mixed models (GLMMs) and Bayesian time-series modeling (CausalImpact). Dose–response experiments established that pupae required 35 Gy and adults 65 Gy to achieve > 99% sterility, with no difference between gamma and X-ray sources. Adult sterilization was effective across 24–96 h post-emergence, facilitating operational flexibility. Handling and transport reduced flight ability by up to 35 percentage points, highlighting cumulative stress effects. In field trials, SIT 1 × yielded limited suppression, with ETD values remaining similar to or higher than those of the control. In contrast, SIT 2 × produced consistent suppression, reducing ETD by 39%, hatch rate by 33%, and female abundance by 51%. In this study, increasing the release frequency was essential to achieve significant model outcomes, representing varying degrees of mild suppression of Ae. aegypti in a complex urban setting. In Addition, male handling, chilling, and transport emphasize the need to reduce the exposure to these parameters by improving the protocols. These results highlight key areas for scaling SIT within integrated vector management strategies in tropical urban settings.
Wolbachia mosquito release cuts dengue cases 50–80 percent
35437Mohamad Al As, Zaf Seraj, New Straits Times, 2026-01-27 18:26:15.
The release of Wolbachia-infected Aedes mosquitoes has led to a 50 to 80 per cent drop in dengue cases in several outbreak areas in Selangor, the Dewan Rakyat was told. Health Minister Datuk Seri Dr Dzulkefly Ahmad said public health studies conducted during the early phase of the programme showed encouraging results. "During the early phase of implementation, the results of public health studies in six dengue outbreak localities in Selangor showed a reduction in dengue cases between 50 per cent and 80 per cent compared with control localities," he said in a written parliamentary reply last night. He was responding to Mohd Hasnizan Harun (PN-Hulu Selangor), who asked whether the ministry has conducted comprehensive environmental and public health impact studies related to the release of Wolbachia-infected mosquitoes. Hasnizan also asked about continuous monitoring mechanisms to ensure long-term safety. Dzulkefly said the early assessments also examined the interaction between Wolbachia-infected Aedes mosquitoes and the existing mosquito population in the environment.
Microhomology-mediated end joining is the predominant form of DNA repair in the mosquito Aedes aegypti with implications for gene editing, gene drive, and transgene removal
35375Joseph S Romanowski, Kevin M Myles, Zach N Adelman, Nucleic Acids Research, 54. 2026-01-20 16:30:25.
Programmable site-specific nucleases have revolutionized the field of genetics, and in the field of mosquito vector control, gene editing by these tools has inspired a new wave of population control approaches that aim to prevent disease transmission. Little is known of how DNA repair is prioritized in mosquitoes, which diverged from the nearest model system (Drosophila) by >200 million years, despite site-specific gene editing now being commonplace. Here, we report a scalable, high-throughput platform for studying DNA double-stranded DNA break (DSB) repair in mosquitoes by delivering CRISPR/Cas9, I-SceI, or other nucleases to Aedes aegypti embryos, capable of measuring single-strand annealing (SSA), non-homologous end joining, and microhomology-mediated end-joining (MMEJ) repair outcomes. We find CRISPR/Cas9 can induce deletions of up to 8.6 kb through SSA repair and is tolerant of resection distances of 3.5 kb. Indel events were insensitive to lig4 knockouts, and across 20 synthetic guide RNAs (sgRNAs) representing 5 locations in 2 transgenic strains were almost exclusively attributed to MMEJ repair, establishing MMEJ as the dominant form of repair in A. aegypti at CRISPR/Cas9 DSBs. This information is critical to our understanding of how DNA repair shapes processes required for genetic control strategies involving gene drive action/resistance as well as transgene stability.
Color-coded mosquitoes safely enables male-only releases to combat Dengue and Zika
35369Joshua Shavit, The Brighter Side of News, 2026-01-16 11:13:48.
Across much of the world, a tiny striped insect shapes whether families stay healthy or get sick. The Asian tiger mosquito carries Dengue, Zika and Chikungunya, and traditional control efforts often struggle to keep up. A new genetic trick that literally changes how these mosquitoes look could help tip the balance in your favor. Only female mosquitoes bite and pass on viruses. Males drink nectar, not blood. Many modern control programs release large numbers of males that are sterile or carry a trait that reduces survival in the next generation. When those males mate with wild females, fewer disease-carrying offspring survive. There is one big catch. These programs must release only males. If too many females slip through, they will still bite, still spread disease and may even weaken the program. Today, most facilities separate sexes by size during the pupal stage. That work is tedious, hard to automate and far from perfect. Researchers led by Doron Zaada and Prof. Philippos Papathanos at the Hebrew University of Jerusalem set out to remove that bottleneck. Their idea was simple and bold. Make male and female mosquitoes so visually different that machines, or even the human eye, can sort them at a glance. The team focused on Aedes albopictus, also known as the Asian tiger mosquito. It is aggressive, invasive and a major target for control programs worldwide. In their study, the scientists describe a “Genetic Sexing Strain” that turns sex into a visible trait. They used CRISPR gene editing to break a gene called yellow that controls dark pigment in the mosquito body. When this gene is disrupted, the insects turn pale, almost albino. The group then restored normal dark pigmentation only in males by linking a working copy of the yellow gene to nix, a sex-determining gene. Nix acts like a master switch. When it turns on in a mosquito, the insect develops as a fertile male, even if it started out genetically female. By tying yellow to nix, the team created a line in which all males are dark and all females remain pale. “This produces an engineered sex-linked trait in mosquitoes that uses the insect’s own genes,” said Prof. Papathanos. “By understanding and controlling the sex determination pathway, we were able to create a system were males and females are visually different at the genetic level.”
Researchers Use Gene Editing to Separate Male and Female Mosquitoes
35367ISAAA Inc., 2026-01-14 11:04:44.
Researchers from the Hebrew University of Jerusalem have developed a new genetic method to separate male and female mosquitoes, which is highly beneficial for large-scale mosquito control programs. Led by Doron Zaada and Prof. Philippos Papathanos, the study aims to improve existing separation strategies that are labor-intensive, difficult to scale, and rely on releasing only male mosquitoes. The study focused on the Asian Tiger mosquito (Aedes albopictus), a major carrier of diseases such as dengue, chikungunya, and Zika. Using CRISPR, the researchers developed a genetically engineered “Genetic Sexing Strain” by disrupting the mosquito's yellow pigmentation gene, then restored dark pigmentation only in males by linking the gene to nix, a “master switch” that converts females into fertile males. This resulted in a stable strain in which males are dark-colored, and females are yellow. The study also found that the yellow females lay eggs that cannot survive dry conditions, unlike wild mosquito eggs that can survive for months. The genetically converted males were shown to behave and reproduce like natural males, indicating their effectiveness for vector control programs. The researchers said that the next step is to improve the female mosquitoes' ability to survive high temperatures or specific additives used in mosquito mass-rearing biofactories.
Florida releases millions of genetically modified mosquitoes from Oxitec in the Florida Keys to try to reduce dengue and Zika by up to 95%, in a real-world experiment that divides residents and ushers in a new era of ecosystem editing.
35351Carla Teles, Click Petróleo e Gás, 2026-01-10 09:57:25.
In a quiet Florida neighborhood, things began with something that seemed mundane. Gray boxes started appearing in backyards and along the edges of mangrove swamps, accompanied by a simple instruction: fill with water and leave. Nobody saw anything special about them, just discreet containers scattered around the neighborhood. What almost nobody realized was that those boxes were capsules for a global experiment: from inside them would emerge millions of mosquitoes. Created in a laboratory, carrying a genetic code designed to attack their own species. In the following months, these boxes became the starting point for waves of millions of mosquitoes A laboratory experiment over the Florida Keys. For some residents, it looked like the beginning of an apocalyptic movie. For others, it was a desperate gamble to contain dengue and Zika outbreaks that had been approaching year after year. And behind it all was Oxitec, a British biotechnology company that transformed a common mosquito into a small flying genetic saboteur.
Analysis of a household-scale model for the invasion of Wolbachia into a resident mosquito population
35327Barlow, A., Penington, S. & Adams, B., Journal of Mathematical Biology, 92. 2025-12-22 12:18:25.
In areas infested with Aedes aegypti mosquitoes it may be possible to control dengue, and some other vector-borne diseases, by introducing Wolbachia-infected mosquitoes into the wildtype population. Thus far, empirical and theoretical studies of Wolbachia release have tended to focus on the dynamics at the community scale. However, Ae. aegypti mosquitoes typically dwell in and around the same houses as the people they bite and it can be insightful to explore what happens at the household scale where small population sizes lead to inherently stochastic dynamics. Here we use a continuous-time Markov framework to develop a stochastic household model for small populations of wildtype and Wolbachia-infected mosquitoes. We investigate the transient and long term dynamics of the system, in particular examining the impact of stochasticity on the Wolbachia invasion threshold and bistability between the wildtype-only and Wolbachia-only steady states previously observed in deterministic models. We focus on the influence of key parameters which determine the fitness cost of Wolbachia infection and the probability of Wolbachia vertical transmission. Using Markov and matrix population theory, we derive salient characteristics of the system including the probability of successful Wolbachia invasion, the expected time until invasion and the probability that a Wolbachia-infected population reverts to a wildtype population. These attributes can inform strategies for the release of Wolbachia-infected mosquitoes. In addition, we find that releasing the minimum number of Wolbachia-infected mosquitoes required to displace a resident wildtype population according to the deterministic model, only results in that outcome about 20% of the time in the stochastic model; a significantly larger release is required to reach a steady state composed entirely of Wolbachia-infected mosquitoes 90% of the time.
Improving Wolbachia-based control programs in urban settings: Insights from spatial modeling
35335Florez D, Cortez R, Hyman JM, Qu Z, PLoS Neglected Tropical Diseases, 19. 2025-12-12 11:08:20.
Arboviral diseases remain a major public health concern, particularly in tropical and subtropical regions where mosquito populations thrive. One promising strategy to curb transmission is the release of Aedes aegypti mosquitoes infected with Wolbachia, a bacterium that reduces their ability to spread viruses. However, past large-scale releases have not always been successful, especially in complex urban settings, where restricted access to certain areas often leads to infection establishment failures and wasted resources. To address this, we developed a spatial model that simulates how Wolbachia-infected mosquitoes are established in different urban environments. We also explored strategies to improve their success under constraints on release size and the efficacy level of insecticide used for pre-release interventions. Our findings suggest that targeted releases are most effective in areas with limited mosquito movement without additional insecticide use. In higher-dispersal areas, reducing at least 35% of wild mosquitoes before release significantly improves establishment within nine months. Additionally, distributing releases over 2-5 weekly batches enhances success more than a single large release, even without other interventions. These findings offer practical insights for designing cost-effective and efficient Wolbachia-based mosquito control programs, reducing the burden of mosquito-borne diseases on vulnerable communities.
This scientist is breeding billions of mosquitoes to fight disease in Brazil
35301Mariana Lenharo, Nature, 2025-12-08 17:09:18.
nside a massive factory in the industrial district of Curitiba, Brazil, millions of Aedes aegypti mosquitoes are breeding in a climate-controlled room filled with mesh cages. Every week, the facility produces more than 80 million mosquito eggs. At the heart of this effort is Luciano Moreira, a soft-spoken agricultural engineer and entomologist, who opened the factory in July as part of an effort to fight mosquito-borne illnesses in the country. At the Curitiba facility, mosquitoes are infected with a bacterium called Wolbachia, which curbs the transmission of harmful human pathogens. Their offspring are being released in Brazilian cities to help to control dengue, a deadly viral disease transmitted mainly by A. aegypti. Until recently, Wolbachia-carrying mosquitoes were released only as part of small-scale research projects. The new factory marks a shift towards nationwide adoption of the method after Brazil’s federal government recognized it as an official public-health measure to combat dengue and other mosquito-borne diseases. People credit Moreira for making the case. “He has succeeded not only in carrying out the academic work, running experiments to demonstrate the model’s effectiveness, but also in convincing political decision-makers to implement the technology,” says Pedro Lagerblad de Oliveira, a molecular entomologist at Brazil’s Federal University of Rio de Janeiro. “This is a skill that not all scientists have.”
Suitability of a chilled environmental box of the Precision X-RAD 320 cabinet style irradiator for the irradiation of mosquitoes and tsetse in the context of the sterile insect technique
35276Hanano Yamada, Bénéwendé Aristide Kaboré, Samar Eisa, et al., Journal of Economic Entomology, 2025-11-03 11:17:02.
A cabinet-style small animal X-irradiator outfitted with an environmental chamber which can provide a consistent, chilled environment during irradiation was tested to sterilize the human and animal disease vectors Aedes aegypti Linnaeus (Diptera: Culicidae), Anopheles arabiensis Patton (Diptera: Culicidae), Glossina palpalis gambiensis Vanderplank (Diptera: Glossinidae) in the frame of the sterile insect technique (SIT). The environmental chamber enables the irradiation of immobilized, compacted adult insects avoiding mechanical damage incurred by movement and, thereby, maintaining better insect quality. For the species tested, there was no significant difference in dose response when irradiating late-stage pupae or adults, and chilling at 7 °C did not affect irradiation outcome in terms of sterility induced. The X-irradiator was shown to be effective and suitable for the sterilization of these important target species of the SIT and offers a practical means to sterilize insects at the adult stage which require chilling for immobilization.
Successful suppression of Aedes aegypti (Diptera: Culicidae) with the sterile insect technique also results in larger female mosquitoes
35257Katherine G Evans, Rachel Morreale, Steven Stenhouse, et al., Journal of Medical Entomology, 2025-10-27 11:04:27.
Sterile insect technique (SIT) is an effective method for controlling pests and has been increasing in popularity to control Aedes mosquitoes. SIT involves inundating an area with sterilized male mosquitoes to reduce egg hatch by reducing the number of fertile matings and ultimately the number of wild adults. Enacting mortality early in the larval life of Aedes mosquitoes can result in counter-productive effects due to reduced competition among developing larvae. SIT projects targeting mosquitoes have historically assessed effectiveness by monitoring egg or adult numbers, leaving out crucial information on what occurs at the larval stage. Our experiments involved collecting and hatching eggs from ovitraps in an SIT-treatment zone and 2 nearby non-SIT zones. We reared the resulting larvae in density and resource conditions similar to those in the field and compared numbers of emerging adults and sizes of emerging adult females from SIT and non-SIT zones. We hypothesize that the effectiveness of SIT in reducing adult populations is modified by density dependent mortality and density dependent growth among larvae. Our results indicate that SIT effectively suppressed the production of adult Aedes aegypti (L) in the SIT zone compared to non-SIT zones. Additionally, female Ae. aegypti, collected as eggs and reared in laboratory-simulated field conditions were significantly larger from the SIT zone than those from the non-SIT zones. Larger SIT-zone females are consistent with reduced intraspecific competition among larvae. Suppression of adult production in the SIT zone resulted in reduced predicted vectorial capacity, despite the increase in female size.
Wolbachia-Based biocontrol of Aedes aegypti: Current Progress, Challenges, and future prospects
35217Ashif Ahamed, Safdar Ali, Mehboob Hoque, Journal of Invertebrate Pathology, 2025-10-05 13:03:30.
Wolbachia is used as potential bio-control tool to reduce the dengue mosquitoes and also to reduce dengue virus (DENV) load in transinfected Aedes aegypti. Different field trials including the ones by the World Mosquito Program (WMP) have deployed Wolbachia carrying DENV primary vectors at different target sites worldwide. Field trials suggest that through the Population Replacement Strategy (PRS) and Incompatible Insect Technique (IIT), Wolbachia can introgress into the local Ae. aegypti population or reduce the population size of the Aedes aegypti by cytoplasmic incompatibility phenomenon and subsequent reduction in dengue incidences at target sites. Challenges for this strategy are to establish and maintain the transinfected mosquito population, choosing the appropriate strain of the bacteria, long term establishment of transinfected dengue mosquitoes for several subsequent generations, selecting the appropriate approach of mosquito field release, operational challenges, and the viral evolution. Moreover, the outcome of Wolbachia mediated biological control of Aedes aegypti in a broad scale is yet to be seen and the long-term stability of Wolbachia in transinfected mosquitoes remains unconfirmed. Significant success has been recorded in a broad scale deployment of wAlbB-carrying Aedes aegypti through the ongoing Wolbachia Malaysia project, resulting in a reduction in dengue fever cases. Successful large-deployment of this strategy has also been performed in Colombia and Indonesia (1.7 to 3.3 million people and 135–540 km2 area). Similar investigations on broad scale for longer period across different environmental conditions using transinfected mosquito deployment and associated risk analysis are imperative before adopting this biological control approach as a potent dengue control strategy worldwide.
Impact of larval diet on fitness outcomes of Aedes aegypti mosquitoes infected with wAlbB and wMelM
35213Md Yatim, M.F., Ross, P.A., Gu, X. et al., Parasites Vectors, 18. 2025-10-02 15:06:04.
Releases of Wolbachia-infected Aedes aegypti are being used to effectively control diseases caused by arboviruses, such as dengue. A well-balanced larval diet is essential for producing Wolbachia-infected mosquitoes with optimal fitness for release. In this study, four diets with varying protein-to-carbohydrate ratios were tested with three Ae. aegypti lines (carrying the wAlbB, wMelM Wolbachia infections or uninfected) to identify optimal diets for larval rearing on the basis of diet allocations ranging from 0.4 to 3.2 mg/larva/day. The diets were selected on the basis of a review of existing literature and are characterized by progressively increasing protein and decreasing carbohydrate content: diet 1 (Pd) was based on plant-based protein (low protein and high carbohydrate), diet 2 (Kd) was based on animal-based protein (moderate protein and high carbohydrate), diet 3 (Fd) involved Hikari fish food (high protein and moderate carbohydrate), and diet 4 (IAEA) followed a widely used very-high-protein and low-carbohydrate diet developed by the International Atomic Energy Agency (IAEA). The optimal concentration for each diet was determined using a fitness index that incorporated pupation success, fecundity, hatch proportion and development time. The optimal dietary allocations for diets 1–4 were 1.6, 1.2, 1.2 and 0.8 mg/larva/day, respectively, regardless of Wolbachia status. There was a consistent significant positive relationship between female wing length and fecundity in wAlbB (r2 = 0.881), wMelM (r2 = 0.329), and uninfected (r2 = 0.886) mosquitoes. Diet 3 (Fd) at optimal food allocation reduced a fitness cost commonly associated with the wAlbB line compared with the uninfected line when provided at the optimal concentration. The wMelM line showed a persistently low fecundity regardless of diet and concentration. These findings highlight the importance of an appropriate larval diet and dietary allocations in optimizing mosquito fitness for Wolbachia-based vector control programs. Further research into dietary composition, gut microbial interactions and Wolbachia associations could refine larval nutrition strategies, enhancing the effectiveness of mass-rearing for release programs.
Effect of egg irradiation on development and sterility of wild-type and Wolbachia trans-infected Aedes aegypti mosquito vectors
35170Kittayapong P, Ninphanomchai S, Thayanukul P, Limohpasmanee W, PLoS One, 20. 2025-09-26 13:56:46.
Sterile Insect Technique (SIT), Incompatible Insect Technique (IIT) or a combination of the two has become alternative promising vector control approaches. In order to apply these approaches, the targeted mosquitoes need to be sterilized and released. So far, the irradiation of mosquitoes has been conducted at the pupae or adult stages. In this study, we investigated the possibility of applying X-ray irradiation at the egg stage and also assessed the effect on the development and sterility of both wild-type and Wolbachia trans-infected Aedes aegypti mosquito vectors. The eggs of both wild-type and Wolbachia trans-infected lines were irradiated using X-ray at the doses of 1, 3, 5 and 7 Gy. Development of immature stages was observed. For wild-type Ae. aegypti, X-ray irradiation at the doses from 3 Gy decreased the development of the first-instar larvae and increased the development of the third-instar larvae but there was no effect on pupae. For Wolbachia trans-infected ones, a irradiation dose as low as 1 Gy could increase the development of the forth-instar larvae while an irradiation dose of 7 Gy induced significantly high mortality to the pupae (p < 0.05). To assess sterility, males and females that emerged from irradiated eggs were mated with the non-irradiated ones. Our results showed that an irradiation dose of 7 Gy significantly caused more than 90% sterility in both wild-type males and females (p < 0.05). However, this irradiation dose could be reduced to 5 Gy to sterilize both males and females infected with Wolbachia. Our findings revealed, for the first time, that applying a low-dose X-ray irradiation at the egg stage could sterilize both wild-type and Wolbachia trans-infected Ae. aegypti when they become adults. Egg irradiation could make the implementation of SIT, IIT or combined SIT/IIT for vector control much more feasible as the sterile eggs are easier to distribute and operate when compared to other developmental stages of mosquitoes.
SELECTING A LARVAL DIET FOR SCALABLE MASS-REARING OF AEDES AEGYPTI IN STERILE INSECT TECHNIQUE APPLICATIONS
35168Aryaprema VS, Blore K, Sypes O, et al., Journal of the American Mosquito Control Association, 2025-09-26 13:51:54.
Controlling Aedes aegypti populations through traditional methods is increasingly difficult due to the development of insecticide resistance and their use of cryptic breeding habitats. The sterile insect technique has emerged as an effective tool for integrated vector management. Still, its success depends on the ability to mass-rear large numbers of high-quality mosquitoes. Choosing an appropriate larval diet is crucial for scalable mass-rearing, as it directly influences mosquito development, survival, and overall production efficiency. This study compared the effects of 3 larval diets: 1) TetraMin® Tropical Flakes, 2) Ziegler® Tropical Pro-Start45 Meal, and 3) bovine liver powder delivered in cellulose capsules, on the growth and performance of male Ae. aegypti under simulated mass-rearing conditions. Ziegler-reared mosquitoes had significantly larger pupal and adult sizes than those reared on Tetramin or liver powder. The Tetramin diet produced smaller adults, but with longevity comparable to that of the Ziegler diet, whereas the liver powder diet resulted in mosquitoes of similar size to those of the Tetramin diet, but with reduced longevity. While all 3 diets demonstrated viability for mass-rearing, their suitability depends on program-specific goals and constraints. The liver powder diet offered a good balance of biological performance and operational efficiency, but at a substantially higher economic cost. With further optimization of feeding regimens, the Ziegler diet shows the most significant potential to deliver high biological quality at the lowest price, making it a strong candidate for scalable mass-rearing programs.
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.
Reprogramming Sex for Vector Control: Maleness-Associated Transgenes in Aedes albopictus
35151Doron Shalom Yishai Zaada, Philippos Aris Papathanos, Eric Marois, Current Opinion in Insect Science, 2025-09-22 10:21:15.
Among other challenges, the world currently faces the expansion of pest insects such as the tiger mosquito Aedes albopictus, a growing threat to public health due to the pathogens it can transmit. Current control approaches based on insecticides or elimination of mosquito larval breeding sites are insufficient to suppress this highly invasive species. The discovery of Nix, a gene necessary and sufficient to determine the male sex in this mosquito, opens new prospects for genetic control strategies, in particular those based on transgenes that convert females into males, or that reduce female fitness. Such forms of genetic control could be effective on larger spatial and time scales compared to classical control approaches. This overview of current and emerging genetic control strategies targeting Aedes mosquitoes emphasizes the unique characteristics of Ae. albopictus, that make it particularly amenable to masculinization-based genetic control.
The Urgent Need for More Research on Wolbachia-Based Mosquito Interventions in Public Health
35133Osvaldo Marinotti, Acta Tropica, 2025-09-15 15:36:56.
The release of Wolbachia pipientis-infected Aedes aegypti mosquitoes has emerged as a novel strategy to reduce the transmission of arboviruses such as dengue, chikungunya, and Zika. Wolbachia-based approaches to dengue control include population replacement, which reduces vector competence by establishing Wolbachia in wild populations of Aedes aegypti, and population suppression, which lowers mosquito densities through cytoplasmic incompatibility. Field trials of the population replacement strategy, based on wMel Wolbachia-infected mosquitoes, have shown variable success and concerns persist about long-term efficacy, safety and ecological impact. Uncertainties arise from an incomplete understanding of the mechanisms underlying pathogen blocking, possible bacteria and vector strain-specific effects, and the influence of environmental, host, and viral factors on the success of such a strategy. Moreover, some Wolbachia strains may enhance mosquito susceptibility to certain pathogens. Additionally, large-scale deployment raises the possibility of biodiversity disruption and the emergence of viral resistance. Given these unresolved concerns, it is premature and potentially irresponsible to expand the program to new areas without first rigorously assessing its safety, efficacy and sustainability.
Application of Sterile Insect Technique (SIT) for Aedes albopictus (Skuse, 1895) in Sri Lanka: Dose optimization, mating competitiveness and release ratios
35114Harishchandra J, Abeyewickreme W, Premaratne R, Hapugoda M, PLoS One, 20. 2025-09-05 08:04:10.
Sri Lanka has experienced severe dengue epidemics in recent years, despite the extensive vector control measures taken. Therefore, it is necessary to find sustainable vector control strategies against dengue. Novel vector control tools need to be tested for the feasibility of applying them against local vectors. Sterile Insect Technique (SIT) is an increasingly popular vector control technique which has been adopted by many countries to suppress insect pest populations and is being tested for dengue vectors. In this study, SIT was developed for Aedes albopictus (Skuse, 1895), one of the 2 dengue vectors present in Sri Lanka. The optimum radiation dose for sterilizing male pupae (age 24–48 hours) using a Co 60 source was determined based on the post-irradiation pupal and adult survival in males and induced sterility in females at different doses. Further, the effect of irradiation on mating competitiveness of the selected mosquito strain was assessed under laboratory and semi-field conditions. The optimum release ratio of irradiated males to wild males was assessed in laboratory and semi-field settings. The optimum radiation dose was 50 Gy among the series of doses (25, 30, 40, 50, 60, and 70 Gy) tested. When pupae were exposed to the optimal radiation dose, 100% pupal survival, 19-day median adult survival time and 99% induced sterility resulted. A 5:1 ratio of irradiated males to non-irradiated laboratory-reared or wild males in laboratory cages resulted in induced sterility of 75% and 62%, respectively. The respective values were 74% and 61% in large semi-field cages. Fried Competitiveness Index (FCI) of irradiated males against wild males of laboratory and wild origin were 0.63 and 0.43 in laboratory cages and 0.57 and 0.55 in large semi-field cages. The males of Ae. albopictus irradiated at 50 Gy are adequately sterile and are competitive against the wild males. The release ratio of 5:1 irradiated males to wild males is a suitable ratio for the field application of SIT. The findings of the study will be important for the development of a protocol for future application of SIT for Ae. albopictus in Sri Lanka.
This is the world’s largest ‘mosquito factory’: its goal is to stop dengue
35109Mariana Lenharo, Nature, 2025-09-03 09:20:02.
When biologist Antonio Brandão tells people that he works at a mosquito factory, they are often baffled. Why would you make more mosquitoes?, he recalls people asking. “We have enough of them.” But once he explains that the laboratory-raised insects can help to stop the spread of dengue — which strikes hundreds of thousands in Brazil each year with fever, headache and bone pain — they come around. Brandão is the production manager, not at just any mosquito factory, but at the world’s largest, located in the southern Brazilian city of Curitiba. Launched in July, the facility is expected to produce 100 million eggs a week from the mosquito Aedes aegypti. However, unlike wild A. aegypti, the main transmitter of dengue virus, those churned out by the factory carry a harmless Wolbachia bacterium that curbs the insects’ ability to spread viruses including dengue and Zika. The idea is to release the modified mosquitoes, which researchers call wolbitos, into cities in Brazil, where they will mate with their wild counterparts and the females will pass the bacterium on to their offspring, gradually converting the local population. The wolbito strategy, which is being spearheaded by the non-profit World Mosquito Program (WMP), has already shown success in Colombia, Indonesia and at home: in the Brazilian city of Niterói in the southeast, dengue cases dropped by 69% in areas where Wolbachia-carrying mosquitoes were released, compared with areas where they weren’t1. Brazil’s federal government has adopted the approach to fight dengue infections — which surged to a record 6.5 million confirmed cases in the country last year — alongside other preventive measures such as vaccines.
Long-Term Durability and Public Health Impact of City-Wide wMel Wolbachia Mosquito Releases in Niterói, Brazil, During a Dengue Epidemic Surge
35107Anders, Katherine L., Gabriel Sylvestre Ribeiro, Renato da Silva Lopes, Pilar Amadeu, Thiago Rodrigues da Costa, Thais Irene Souza Riback, Karlos Diogo de Melo Chalegre, Wesley Pimentel de Oliveira, Cátia Cabral da Silva, Marcos Vinicius Ferreira Mendes B, Tropical Medicine and Infectious Disease, 10. 2025-09-02 18:57:03.
In 2024, the Americas experienced the largest dengue outbreak on record and Brazil was among the worst affected countries, reporting 6.6 million cases and 6200 deaths. We report the long-term entomological and epidemiological effectiveness of city-wide deployment of wMel-strain Wolbachia-infected Aedes aegypti in Niterói, a city of half a million people in Rio de Janeiro state, where Wolbachia releases across three-quarters of the urban population in 2017–2019 were expanded to remaining populated areas in 2023. wMel was durably established at ≥95% prevalence in Ae. aegypti populations throughout Niterói four years post-release, and up to seven years in the earliest release sites. Notified dengue case incidence in Niterói was 89% lower following Wolbachia releases, compared to the 10-year pre-intervention period of 2007–2016. Dengue incidence in Niterói in 2024, during a period of record high incidence in Brazil and the region, was 374 per 100,000 population, substantially lower than overall in Rio de Janeiro state (1884 per 100,000) and nationwide in Brazil (3157 per 100,000). Our findings show that city-wide Wolbachia coverage in Niterói provided sustained population-level reduction in dengue incidence throughout the five years post-intervention, including during the 2024 epidemic surge, averting an estimated three-quarters of the dengue case burden that may otherwise have been expected in Niterói in 2024.
Comparison of the standard and boosted sterile insect techniques for the suppression of Aedes albopictus populations under semi-field conditions
35085Marlène Dupraz, Renaud Lancelot, Gorgui Diouf, et al., Parasite, 32. 2025-08-28 18:38:54.
Innovative control tools are needed against Aedes mosquitoes. The boosted sterile insect technique (bSIT) consists of treating sterile males with a biocide prior to their release to contaminate larval habitats. We compared the efficacy of SIT and boosted SIT to prevent the emergence of adult Aedes albopictus in large cages. We tested two sterile-to-fertile male ratios: 5:1 (SIT5) and 1:1 (SIT1), with and without pyriproxyfen enhancement (bSIT or SIT). The eggs were collected in ovitraps and the immature stages were monitored until adult emergence or up to 15 days after hatching to estimate the relative risk (RR) of adult emergence compared to the control category. The concentration of pyriproxyfen in the ovitrap water did not change when sterile males were released with females or alone (χ2 = 0.99, df = 1, p = 0.547). This concentration was higher when the sterile-to-fertile male ratio was increased from 1:1 to 5:1: χ2 = 18.8, df = 1, p = 0.006. All four treatment categories were effective in suppressing mosquito populations. With a relative risk RR = 0.194 95% CI [0.128; 0.275], SIT5 was the most effective. Boosted SIT was not as effective as SIT. However, bSIT1 (RR = 0.418 [0.351; 0.492]) and bSIT5 (RR = 0.512 [0.431; 0.596]) were equally effective. Boosted males directly vectored pyriproxyfen to breeding sites. Boosted SIT was more effective than SIT alone with a low sterile-to-fertile male ratio. Under operational conditions, it could be initially deployed to suppress the target population and then switched to standard SIT.
Effectiveness of the sterile insect technique in controlling Aedes albopictus as part of an integrated control measure: evidence from a first small-scale field trial in Switzerland
35042Parrondo Monton, D., Ravasi, D., Campana, V. et al., Infect Dis Poverty, 14. 2025-08-24 16:54:24.
The invasive Asian tiger mosquito (Aedes albopictus) poses growing health risks across Europe. In Switzerland, a preliminary field trial was conducted to assess the feasibility of integrating the sterile insect technique (SIT) into existing integrated vector management (IVM), which includes breeding site removal and application of biological larvicides. SIT involves repeated releases of irradiated sterile males, which mate with wild females, producing non-viable eggs and leading to population decline. Following a preliminary release test in 2022, a small-scale SIT trial took place in 2023 in Morcote, Switzerland. Approximately 150,000 sterile males were released weekly over a 45-hectare area throughout the entire mosquito activity season, from May to September. This SIT area also received routine IVM. Population dynamics were compared with a control area where only IVM was applied. Monitoring included egg counts, hatch rates, and adult female densities. Generalized additive mixed-effects models (GAMM) and generalized additive models (GAM) accounted for spatial, temporal, and random effects. Model selection used AIC, BIC, and Chi-square tests (significance at 5%). The SIT-treated area showed a significant mosquito population reduction. Egg counts dropped by 57% (GAMM regression coefficient: − 0.8513, P < 0.001), with temporal patterns differing between SIT-treated and control areas (P < 0.001). Egg hatch rates were also lower in the SIT area, with odds of hatching reduced by 1.24 log-odds units (P < 0.001). Adult female densities declined by 66% (regression coefficient: − 1.0818, P < 0.001). Spatial GAMs revealed heterogeneous effects: up to 90% egg reduction in the western release area, while the eastern edge, bordering untreated zones, showed up to 300% higher egg counts. Similar spatial trends were observed for hatch rates and adult females (P < 0.01). These findings highlight both the overall effectiveness of SIT and the influence of mosquito immigration on spatial patterns. This trial demonstrated the potential of SIT as a complementary tool in Swiss vector control. Public interest and acceptance were high. To improve cost-effectiveness, further optimization of male production, sterilization, transport, and release processes is needed. Continued implementation over multiple seasons is recommended to enhance long-term effectiveness.
How biotech helps Florida Keys prevent mosquito-borne diseases
35029Janine Stanwood, Local 10, 2025-08-17 19:49:34.
Biologists with the Florida Keys Mosquito Control District (FKMCD) are releasing lab-modified mosquitoes twice a week in the Middle Keys. It’s part of a pilot program to reduce the population and help stop people from getting bitten. “They’re male Aedes aegypti,” said Dr. Larry Hribar, FKMCD Director of Research. “They’re infected with a mosquito parasite that’s in the genus Wolbachia.” There are dozens of species of blood suckers in South Florida, including the nuisance salt marsh mosquito found in mangroves and in the Everglades. But it’s the Aedes aegypti that carries diseases like Zika and dengue. “That’s the one that vector the diseases we worry about,” said FKMCD spokesperson Chad Huff. The males, shipped from a company called MosquitoMate, have been infected with the Wolbachia bacteria before mating with females after being released. “They’ll find a local female, they’ll mate, but the eggs she produces are not going to be viable,” Hribar said. According to the Centers for Disease Control, the lab-infected mosquitoes can’t make people or animals sick.
Millions of genetically modified insects have been released in Brazil, but why didn’t anyone tell you about this before?
35003Noel Budeguer, Click Petroleo e Gas, 2025-08-04 08:29:56.
Few people realize, but Brazil is one of the most advanced countries in the world when it comes to biological pest control. Instead of relying solely on poisons and traps, Brazilian researchers are investing in technological solutions that, at first glance, seem like the stuff of science fiction: releasing modified mosquitoes and flies into the environment to prevent disease outbreaks and agricultural losses. The initiative may sound controversial, but it has already yielded impressive results—and, in some cases, may have prevented entire epidemics without anyone noticing. The logic behind these techniques is simple yet powerful. By releasing sterile or genetically modified males into the environment, they compete with natural males for females. When they win this contest and mate, the offspring born don't survive—or even hatch at all. The result is a drastic decline in the target pest's population. Two main approaches are used: the Sterile Insect Technique (SIT), which uses radiation to sterilize males, and genetic modification, which prevents reproduction through DNA alterations. Both methods eliminate the use of pesticides and have gained traction as sustainable and highly effective alternatives.
Threshold-dependent improvement in sex separation efficiency by NaCl pretreatment of larval–pupal mixtures in mass-reared Aedes albopictus
34996Yan Sun, Junyan Zhang, Keqing Zheng, et al., Pest Science Management, 2025-07-30 12:54:37.
The removal of female mosquitoes is a critical requirement in sterile insect technique (SIT) for mosquito control. Improving the efficiency and accuracy of sex sorting is therefore vital. Previous studies have demonstrated that treating larval–pupal mixtures with a 15% sodium chloride (NaCl) solution prior to the sex sorting process reduces female contamination in Aedes mosquitoes. However, the effects of NaCl on Aedes albopictus mosquito biology and its practical application in production facilities remain insufficiently explored and warrant further investigation. Exposure of larval–pupal mixtures to 15% NaCl for 60 min led to 100% larval mortality via osmotic imbalance and intestinal tissue damage, while pupae remained unaffected due to their impermeable cuticle. Males emerging from treated pupae exhibited comparable emergence, longevity, and flight ability to controls, indicating no adverse effect on male quality. NaCl pretreatment significantly improved sorting efficiency and reduced female contamination in manual sorting, achieving a 3.9-fold reduction in adult-stage contamination. Although automatic sorters increased throughput, reductions in female contamination were not statistically significant. Importantly, the sorting benefits of NaCl treatment were threshold-dependent and most evident at larger processing scales. NaCl pretreatment is a simple, scalable, and biologically safe strategy to enhance sex separation in Ae. albopictus mass production. It is particularly advantageous under high-throughput conditions and preserves male fitness, supporting the stringent quality standards required for successful SIT-based mosquito control.
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.
Implications of successive blood feeding on Wolbachia-mediated dengue virus inhibition in Aedes aegypti mosquitoes
34989Johnson, R.M., Breban, M.I., Nolan, B.L. et al., Nat Commun, 16. 2025-07-30 10:55:57.
Wolbachia is a promising strategy to inhibit dengue virus (DENV) transmission by Ae. aegypti mosquitoes. Laboratory studies assessing DENV inhibition by Wolbachia typically have not considered natural frequent mosquito blood feeding behavior. Here, we determine the impact of successive feeding on DENV-2 transmission by Ae. aegypti in the presence or absence of Wolbachia (wAlbB and wMelM strains). We show that successive feeding shortens the extrinsic incubation period (EIP) in wildtype (WT; without Wolbachia) and wAlbB mosquitoes through enhanced dissemination. Feeding empirical data into models showed that successive feeding increases the probability of WT and wAlbB mosquitoes surviving beyond the EIP. Importantly, the more epidemiologically relevant comparison of the odds of wAlbB mosquitoes surviving beyond the EIP relative to WT, reveals a larger impact of successive feeding on WT than wAlbB. This indicates a strong inhibitory effect of Wolbachia even in the context of natural frequent mosquito blood feeding behavior.
Vector Control District Plans Experimental Mosquito Control Program
34982Contributing Editor, MyNewsLA.com, 2025-07-24 09:51:29.
Batches of irradiated male mosquitoes are slated for release Wednesday in Lake Elsinore with the goal of pairing the modified insects with as many females as possible to kill off the overall mosquito population, under an experimental program that apparently hasn’t generated concerns among public officials. The “Sterile Insect Technique Pilot Program” is being managed by the Northwest Mosquito & Vector Control District, which serves segments of western Riverside County. The district is believed to be the first countywide to inaugurate an SIT mosquito control program. Questions regarding when it was authorized, the estimated number of modified mosquitoes that will be released and any potential public health risks were not answered by the agency as of Tuesday afternoon. Lake Elsinore officials also did not respond to requests for comment. The West Valley Mosquito & Vector Control District, which encompasses Ontario, Montclair and neighboring municipalities in San Bernardino County, was the first district in California to receive authorization from state regulators to initiate mosquito SIT releases last year, under a pilot program similar to that of the Northwest Mosquito & Vector Control District. It’s still unknown whether West Valley’s experimental program has netted any benefits. “Sterile male mosquitoes are released to mate with local females, and the resulting eggs are unable to hatch,” NMVCD said in a statement regarding the Lake Elsinore program. “The release of adult male mosquitoes will not increase local bite pressure, as only female mosquitoes bite.”
Integrated vector management with the sterile insect technique component for the suppression of Aedes aegypti in an urban setting in Indonesia
34954Sasmita HI, Neoh K-B, Ernawan B, Indarwatmi M, Nasution IA, Fitrianto N, et al., PLoS Neglected Tropical Diseases, 2025-07-08 13:14:26.
The sterile insect technique (SIT) involves subjecting laboratory-bred male mosquitoes to radiation, typically gamma rays, X-rays, or electrons, that render them sterile. These sterile male mosquitoes are then released into the field to mate with wild female mosquitoes. From that mating, no viable eggs are produced. The SIT is a mosquito population control strategy that prevents the spread of the dengue virus through Aedes aegypti female mosquitoes. Considerable progress has been made regarding the SIT, and its effectiveness has been tested in numerous regions for managing local mosquito populations. In the present study, the field performance of sterile male mosquitoes was evaluated through a mark–release–recapture study, which was followed by an SIT trial. In an SIT pilot trial, pre-release control measures, including insecticide application and mosquito breeding site removal, were applied within the framework of integrated vector management. Community engagement activities were designed to ensure community acceptance and support for the SIT. The trial led to substantial reductions in the egg hatching, numbers of eggs and female mosquitoes despite challenges related to sterile male production and population isolation. This study revealed the key factors contributing to the success of an SIT trial to be the field performance of sterile male mosquitoes, complementary vector control methods, population isolation, and support from local residents.
Evaluating the performance of three packing methods for long-distance transport of sterile adult Aedes albopictus males
34893Mamai, W., Puggioli, A., Wallner, T. et al., Scientific Reports, 15. 2025-06-06 08:21:38.
This study evaluated the performance of three packing methods for long distance transport of sterile adult Aedes albopictus males, considering the specific effects of pupal vs. adult irradiation and two compaction methods. The results indicated that while transportation significantly impacted the quality of sterile males, all the three packing methods (IAEA V.1.0, IAEA V.2.0, and CAA) tested under simulated transportation durations of 25–48 h resulted in average mortality rates below 12%, with male escape rates ranging between 30 and 50% after a 24-h recovery period. The transported males were able to survive for about 2 days under stress conditions. Additionally, adult irradiation led to higher male survival and escape rates than pupal irradiation, for both before and after transportation. The study also found that stacked cups were more effective as compaction method than the square plastic boxes, despite having a reduced maximum transport capacity. Providing sterile males with 10% sugar for a 24-h recovery period after transportation, also played a role in enhancing escape rate and survival. Although Ae. albopictus prove to be more sensitive to packaging and shipping procedures compared to Aedes aegypti, this study provides valuable insights for developing and improving handling packing and shipping guidelines.
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.
Suppression of Aedes mosquito populations with the boosted sterile insect technique in tropical and Mediterranean urban areas
34854Bouyer, J., Gil, D.A., Mora, I.P. et al., Scientific Reports, 15. 2025-05-26 20:31:16.
Aedes mosquitoes are the vectors of dengue viruses and other arboviruses, which threaten billions of people all over the world. The boosted sterile insect technique (boosted SIT) is a version of SIT in which irradiated sterile males also transmit a biocide to immature stages. We describe three field trials that were run in 2021: one against Aedes aegypti in La Reunion and two against Aedes albopictus in Spain, each using pyriproxyfen as a biocide. The relative density of adults (compared to their density in control sites: without sterile male release) decreased from 1.00 to 0.09, 95% credible interval [0.06, 0.15] (La Reunion, July) and to 0.02 [0.01, 0.03] and 0.11 [0.08, 0.16] (Spain, July and October). The success rate, corresponding to the proportion of traps with suppression greater than 80%, ranged from 0.43 to 0.71 in La Reunion, from 0.26 to 1.00, and from 0.50 to 0.70 in Spain. In Spain, suppression with boosted SIT was higher than with non-boosted SIT, in 2020 and 2022. This work is in line with the predictions of the model of a better efficacy of boosted SIT compared to SIT, together with partial protection from invasion of treated areas by fertile females, paving the way for larger-scale field trials.
Overview of the sterile insect technique for Aedes aegypti in Lee County, Florida, USA
34841Morreale, R., Stenhouse, S., Bajonero, J. et al., Infectious Diseases of Poverty, 14. 2025-05-12 20:10:08.
Lee County Mosquito Control District (LCMCD) is an independent taxing district that works to protect human health and improve quality of life in Lee County, Florida, USA. With local dengue transmission in southern Florida, LCMCD prioritized the control of Aedes aegypti. Due to the cryptic larval habitats of Ae. aegypti and insecticide resistance, effective control using conventional methods is difficult. Thus, the sterile insect technique (SIT) program, using X-ray irradiated male mosquitoes, was created to target Ae. aegypti. The goal of this program was to suppress Ae. aegypti through establishing a robust SIT program and performing a pilot study in the field to assess the impacts of SIT releases. The SIT program at LCMCD released sterile male Ae. aegypti from 2020 to 2022 in Captiva Island, Florida. The SIT program works within a larger Integrated Mosquito Management (IMM) framework and is not a standalone tool. The SIT program consists of nine employees, one of which is dedicated to quality assurance. Quality assurance assessments are performed routinely and periodically. Due to widespread destruction throughout Captiva and Sanibel Islands from Hurricane Ian in September 2022, the SIT pilot in Captiva Island was concluded and moved to Fort Myers, Florida. During the pilot study on Captiva Island, various lessons were learned and this knowledge has been applied to efforts in Fort Myers. LCMCD has established a successful SIT program to suppress populations of Ae. aegypti. Through connections with the International Atomic Energy Agency (IAEA) and the University of Florida, LCMCD received guidance from experts in the field to help ensure the program’s success. Stable funding through taxes levied specifically for mosquito control provided essential consistency, allowing the program to grow and evolve. Consistent trapping routines provided immense amounts of entomological data. Thoughtful and intentional community engagement was essential in ensuring acceptance of the SIT program in Lee County. Following the phased conditional approach suggested by IAEA, LCMCD has built an effective and resilient SIT program. The integration of the SIT as a tool of an area-wide mosquito control program is a feature that distinguishes LCMCD’s SIT program from others.
Differential elimination of marked sex chromosomes enables production of nontransgenic male mosquitoes in a single strain
34839A. Compton, A. Sharma, M. Hempel, A. Aryan, J.K. Biedler,M.B. Potters, K. Chandrasegaran, C. Vinauger, & Z. Tu, Proceedings of the National Academy of Sciences, 122. 2025-05-12 20:01:30.
Diverse genetic strategies are being pursued to control mosquito-borne infectious diseases. These strategies often rely on the release of nonbiting males to either reduce the target mosquito population or render them resistant to pathogens. Male-only releases are important as any contaminating females can bite and potentially transmit pathogens. Despite significant efforts, it remains a major bottleneck to reliably and efficiently separate males from females, especially when nontransgenic males are preferred. In the yellow fever mosquito Aedes aegypti, sex is determined by a pair of homomorphic sex chromosomes, with the dominant male-determining locus (the M locus) and its counterpart (the m locus) embedded in an M-bearing and an m-bearing chromosome 1, respectively. We utilized both naturally occurring and engineered sex-linked recessive lethal alleles (RLAs) to create sex separation strains for Ae. aegypti on the basis of differential elimination of marked sex chromosomes (DeMark). DeMark strains are self-sustaining and produce nontransgenic males that are readily separated from individuals carrying RLA- and transgene-marked m chromosomes. For example, the marked m chromosome in the heterozygous mother in some strains was only inherited by her female progeny due to RLA-mediated incompatibility with the M-bearing chromosome in the father, producing nontransgenic males and transgenic females, generation after generation. We further explore strategies to conditionally eliminate females that contain marked sex chromosomes. We also discuss DeMark designs that are applicable for efficient sex separation in organisms with well-differentiated X and Y chromosomes, such as the Anopheles mosquitoes.
Mosquito Miracle: Breakthrough Brings Hope for Bangladesh in Dengue Fight
34837Staff Correspondent, Digi Bangla Tech, 2025-05-10 19:42:52.
A major scientific breakthrough is offering new hope for Bangladesh in its battle against dengue. An international team of researchers has successfully developed a strain of Aedes aegypti mosquitoes infected with Wolbachia bacteria, which are capable of adapting to the local environment of Dhaka city. Dubbed as “good mosquitoes,” this innovation opens a new, safe, and biological pathway for controlling the spread of dengue and other mosquito-borne arboviral diseases in the country, according to the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b). The research team includes scientists from QIMR Berghofer Medical Research Institute in Australia, the University of Queensland, icddr,b, and the United States Centers for Disease Control and Prevention. The findings were recently published in the journal Nature’s Scientific Reports. According to icddr,b, dengue has emerged as a severe public health threat in Bangladesh. In 2023 alone, a record 321,000 people were infected, with more than 1,700 deaths—making it the deadliest year on record. Rapid urbanization, erratic rainfall, and rising temperatures have contributed to the spread of Aedes mosquitoes, the primary vector of dengue. Simultaneously, the effectiveness of conventional insecticide-based mosquito control methods is declining due to growing resistance among mosquito populations. This has prompted scientists worldwide to seek more sustainable solutions, with the use of "good mosquitoes" being one of the most promising. Researchers explained that Wolbachia was chosen because it prevents Aedes mosquitoes from transmitting dengue, chikungunya, and Zika viruses, without harming humans or the environment. Wolbachia is a naturally occurring bacterium found in butterflies, fruit flies, and some mosquito species, though not in Aedes aegypti. This bacterium cannot infect humans or animals, nor is it transmissible through bites or contact.
Impact of sterile Aedes aegypti males releases on vector dynamics: insights from Malaysian field trials
34815Nazni, W.A., Teoh, GN., Nuradila, M.A. et al., Infectious Diseases of Poverty, 14. 2025-05-04 16:00:48.
The Sterile insect technique (SIT) has been successfully used in agricultural pest control, leading to interest in its application for public health, particularly in controlling Aedes mosquitoes in the USA, Italy, Cuba, and Greece. Malaysia has conducted a small-scale SIT pilot trial since 2019 for dengue control. This study evaluates mosquito populations in treated and untreated sites through three objectives: (1) comparing mean larvae per trap (MLT) and dengue cases for Ae. aegypti and Aedes albopictus; (2) estimating survival rates and wild populations using mark-release-recapture (MRR); and (3) analysing spatial distribution in treated and untreated sites. Ae. aegypti males, irradiated at 55 Gray, were released in three locations: Pangsapuri Kota Laksamana (KT), Malacca (19 months), Pangsapuri Taman Tasik Utama (TTU), Malacca (8 months), and the Customs, Immigration, and Quarantine Complex (CIQ), Johor (7 months). Statistical analyses assessed SIT effectiveness, including T-tests for larval density and ovitrap indices, Mulla’s formula and relative variance (RV) for population reduction, and the Lincoln Index for estimating wild male populations and probability of daily survival. Weekly releases of sterile Ae. aegypti males at doses of 1278–7942 males/ha achieved a sterile-to-wild male ratio of 5.85 and a mean daily survival rate of 0.61, leading to significant reductions in larval densities: 76.25% in Kota Laksamana (KT), 96.74% in Taman Tasik Utama (TTU), and 89.00% in CIQ Gelang Patah, thereby supporting dengue control efforts. In KT, the MLT was initially low but increased, although with suppression < 90%, there was a reduce of dengue cases throughout the release period. The MRR’s mean survival rate (± standard deviation) in KT was 0.61 (± 0.08). The spatial clustering of Ae. aegypti was observed in central blocks during the high MLT period. However, larval densities rebounded after releases ceased. Spatial clustering revealed no initial clustering, though clustering patterns emerged over time in KT. SIT effectively suppressed Ae. aegypti populations and supported dengue control. Optimizing sterile-to-wild male ratios, spatial distribution, and monitoring strategies is essential for sustainable vector control. These findings provide insights for scaling up SIT field trials, with future efforts focusing on refining release and monitoring strategies to enhance SIT as an effective dengue control tool. Trial registration NMRR-17–2652-39,099 “Field evaluation of Sterile Insect for Aedes aegypti Suppression.”
Optimizing Cost-Effective Larval Diets for Mass Rearing of Aedes Mosquitoes in Vector Control Programs
34810Li, Q., Wei, T., Sun, Y., Khan, J., & Zhang, D., Insects, 16. 2025-05-04 15:43:50.
Larval diet composition significantly influences the developmental, physiological, and reproductive traits of Ae. albopictus and Ae. aegypti, major arbovirus vectors. Optimizing larval nutrition is essential for mass-rearing programs supporting the sterile insect technique and incompatible insect technique. This study evaluated the effects of three larval diets on key fitness traits, including pupation rate, male flight ability, adult longevity, female fecundity, pupal size, and wing length, which are critical for the success of SIT and IIT programs. (2) Methods: Ae. albopictus (GT strain) and Ae. aegypti (AEG strain) were reared on three diets with varying protein sources: diet 1 (≈1.23 dollars/kg; porcine liver/shrimp/yeast = 6:3:1), the IAEA-recommended diet; diet 2 (≈1.78 dollars/kg; bovine liver/shrimp/yeast = 6:3:1), a modified IAEA diet; and diet 3 (≈0.55 dollars/kg; tortoise food), a low-cost laboratory formulation. Life history traits were assessed using standardized protocols, and data were analyzed with ANOVA and Tukey’s post hoc test. (3) Results: Diet 3 consistently improved pupation rates, adult longevity, and male flight ability compared with diet 2. Mosquitoes reared on diets 1 and 3 exhibited significantly larger pupae and longer wings, while diet 2 performed sub-optimally. Adult eclosion rates (~100%) remained high across all diets. Male flight ability varied by species, with Ae. albopictus performing best on diet 1 and Ae. aegypti on diet 3. Female fecundity was diet-dependent, with diet 1 favoring Ae. albopictus and diet 3 benefitting Ae. aegypti. Longevity was highest in mosquitoes reared on diet 3, with a median survival of 19.5 days for GT males and 37.5 days for GT females. (4) Conclusions: Diet 3 emerged as the most cost-effective option, enhancing key fitness traits essential for SIT and IIT. Future studies should refine nutrient formulations and validate findings under field conditions to optimize mass-rearing efficiency in vector control.
Synthetic Homing Endonuclease Gene Drives to Revolutionise Aedes aegypti Biocontrol – Game Changer or Pipe Dream?
34756Joshua X.D. Ang, Sebald A.N. Verkuijl, Michelle A.E. Anderson, Luke Alphey, Current Opinion in Insect Science, 2025-04-10 09:10:46.
The increasing burden of Aedes aegypti-borne diseases, particularly dengue, is a growing global concern, further exacerbated by climate change. Current control strategies have proven insufficient, necessitating novel approaches. Synthetic homing endonuclease gene (sHEG) drives represent one of the few emerging technologies with the potential to offer a cost-effective and equitable solution to this escalating public health challenge. However, despite multiple attempts, the homing efficiencies of Ae. aegypti sHEG systems lag behind those achieved in Anopheles mosquitoes. We discuss key insights from efforts to develop sHEGs in Ae. aegypti and highlight critical factors that may unlock further advances in this species.
Comparison of oviposition and adult trapping to monitor wMel introgression for Wolbachia-based vector control
34738Nelson, E., Pereira, T.N., Ribeiro E., et al., bioRxiv, 2025-04-03 17:36:42.
Wolbachia introgression into Aedes aegypti mosquito populations has been shown to be effective in preventing dengue and is being evaluated for WHO prequalification. Monitoring the long-term introgression of Wolbachia (wMel)-positive Aedes aegypti mosquitoes, however, requires labor-intensive and costly BG-Sentinel traps (BG-traps). More affordable alternatives, such as using oviposition traps (ovitraps), have not been fully evaluated. Ae. aegypti eggs and adults were collected from 124 ovitraps and 237 BG-traps, respectively, across 12 clusters in Belo Horizonte, Brazil from March to May 2023 as part of the EVITA Dengue trial. We used a qPCR assay to detect wMel in a sample of L3-L4 stage larvae (up to 29) that were reared from eggs in ovitraps and adults from BG-traps (up to 10 per BG-trap). We used mixed effects models to compare estimates of cluster-level wMel introgression from ovitrap and BG-trap data over time. Among 3,675 larvae reared from ovitraps, wMel prevalence was 0.50 (95% CI: 0.48-0.51). Among 1,244 adult Ae. aegypti tested from BG-traps, wMel prevalence was 0.45 (95% CI: 0.42-0.48). Cluster-level wMel introgression in larvae and adults was highly correlated (Spearman’s r = 0.70, p = 6.71e-06). Multivariate analysis found that ovitrap estimates of introgression were associated with BG-trap estimates in the same month when models incorporated the previous month’s ovitrap wMel-positive count, the proportion of wMel in ovitraps in the current and previous month, and Ae. aegypti abundance. Leveraging this model, predicted wMel introgression from ovitrap data were highly correlated with observed introgression from BG-trap data (rs,counts=0.98, p=1.53e-14; rs,prevalences=0.82, p=0.11e-05) and provided greater precision than crude ovitrap-based estimates.
Mosquito Sex Separation using Complementation of Selectable Traits and Engineered Neo-Sex Chromosomes
34736Zaada, D.S.Y., Toren, O., Krsticevic, F., et al., bioRxiv, 2025-04-03 17:26:54.
Effective and scalable sex separation remains a critical challenge for mosquito genetic control strategies. Genetic sexing strains (GSS) address this by genetically linking maleness with selectable traits, enabling efficient removal of females before release. Here, we describe a robust platform for the development of GSSs in the invasive Aedes albopictus mosquito by integrating a CRISPR-engineered selectable phenotype with sex conversion via nix, the male-determining factor. As a proof-of-concept, we disrupt the yellow gene to generate a vivid pigmentation marker, then rescue its function in males using nix-containing transgenes, creating a stable strain where all females are yellow and all engineered males are dark. The resulting GSS males are fertile, robust, and despite lacking the ancestral M locus, exhibit gene expression profiles closely resembling wild-type males. We benchmark sex separation based on pigmentation and discover that yellow mutant females exhibit slower larval development, enhancing protandry-based sorting. The GSS strain is compatible with existing size-based sex sorting systems, allowing for improved separation accuracy through the integration of natural and engineered sexually dimorphic traits. Additionally, we find that GSS females lay desiccation-sensitive eggs, reducing the risk of accidental female releases. Our approach is the first to engineer a sex-linked selectable trait by precisely targeting an endogenous gene and restoring its function in males, establishing a versatile platform for GSS development in Aedes mosquitoes.
Genetically modified mosquitoes released in the US: How they can prevent disease outbreaks
34732TOI Lifestyle Desk, Times of India, 2025-04-02 16:42:21.
The menace of mosquito-borne illnesses is growing in the US and the contributing factors range from climate change to their expanding habitats. The solution could lie in genetically modified mosquitoes that hold the capability to effectively control mosquito populations. Recently, genetically modified mosquitoes were released in Florida, US, following the successful trials in Brazil, the Cayman Islands, Panama, and Malaysia, where populations of aedes aegypti dropped by at least 90%. A significant step forward in preventing the deadly mosquito-borne illnesses, the bioengineered male aedes aegypti mosquitoes were introduced into the environment. While these deadly species make up for 4% of the total local mosquito population, they are enough to wreak havoc. It is to be noted that female aedes aegypti mosquitoes are the primary vectors that can transmit dengue, Zika, yellow fever, and chikungunya viruses to humans.
Mark-Release-Recapture of Packed and Shipped Aedes aegypti with Wolbachia: Implications for Conducting Remote Incompatible Insect Technique Programs
34640Ohm, J. R., Lynd, A., McGowan, A., et al., The American Journal of Tropical Medicine and Hygiene, 2025-03-21 14:44:30.
Male mosquitoes containing the endosymbiont Wolbachia (Wb+) can be used as a tool to suppress wild mosquito populations through a technique termed incompatible insect technique (IIT). IIT programs reduce wild mosquitoes via incompatible matings between released males and wild females to reduce the number of viable offspring produced in the next generation. Successful programs rely on regular release of incompatible males to outcompete wild males for female mates. Past IIT programs have relied on local production of Wb+ males to support regular releases of incompatible males. Here, we evaluated the survival and dispersal of packed and shipped Wb+ Aedes aegypti males in mark-release-recapture studies at a release site in the British Virgin Islands (BVI), separated by over 3,600 miles from the centralized production facility. Released mosquitoes were recaptured using BG-Sentinel 2 traps collected daily for up to 7 days after release. Wb+ male mosquitoes packed and shipped from a centralized production facility performed similarly to males that were locally reared in the BVI in survival, dispersal, and recapture rates. Our results support the conclusion that packing and shipping live Wb+ male mosquitoes does not impact their ability to survive and disperse in release sites and suggests that IIT mosquito control programs can feasibly be conducted nearly anywhere in the world without the need for local mosquito production facilities.
3 reasons why the release of GM mosquitoes in Queensland is risky
34554Dr. Perran Stott-Ross, University of Melbourne, 2025-03-04 11:14:23.
The British company Oxitec, in partnership with Australia's CSIRO, has announced plans to release genetically modified (GM) mosquitoes in Queensland. The initiative aims to reduce transmission of the dengue virus, as well as other pathogens spread by the Aedes aegypti mosquito by reducing the size of the mosquito population. The announcement has received significant attention from the public – there's even a petition to the Queensland Parliament to block the release. While these mosquitoes are unlikely to cause adverse health impacts as some have suggested, there are still legitimate reasons for concern. Here is why we should be wary of releasing GM mosquitoes in Australia. Only female mosquitoes drink blood to feed their eggs, meaning only female mosquitoes spread disease to humans. The mosquitoes developed by Oxitec are a Mexican strain of Aedes aegypti, genetically engineered to express a gene that's lethal to females. This means only male mosquitoes can survive and reproduce in the wild. Male mosquitoes don’t bite so they can’t spread disease, but they can still mate with wild Australian female mosquitoes and pass on their genes – both the lethal gene and other genes naturally occur in the Mexican strain of Aedes aegypti. This technique has advantages over similar technologies because it is effective across multiple generations, making the population reduction last longer. It will also only target Aedes aegypti and won’t affect other mosquito species directly. The mosquitoes will also carry a fluorescent gene making them easy to identify. The GM mosquitoes will be sold to businesses and the public, allowing anyone in Queensland to release them on their own property. They can be raised by adding water to a container and placing it outside. Eventually, male mosquitoes will emerge to mate with the wild population. The technology is already used overseas with trials showing drastic reductions in mosquito populations, but the situation in Australia is markedly different and so carries different risks.
Exploiting venom toxins in paratransgenesis to prevent mosquito-borne disease
34533French, S., Da Silva, R., Storm, J. et al., Parasites & Vectors, 18. 2025-02-21 11:33:53.
Mosquitoes are responsible for the transmission of numerous pathogens, including Plasmodium parasites, arboviruses and filarial worms. They pose a significant risk to public health with over 200 million cases of malaria per annum and approximately 4 billion people at risk of arthropod-borne viruses (arboviruses). Mosquito populations are geographically expanding into temperate regions and their distribution is predicted to continue increasing. Mosquito symbionts, including fungi, bacteria and viruses, have desirable traits for mosquito disease control including spreading horizontally and vertically through mosquito populations and potentially colonising multiple important vector species. Paratransgenesis, genetic modification of mosquito symbionts with effectors to target the pathogen rather than the vector, is a promising strategy to prevent the spread of mosquito-borne diseases. A variety of effectors can be expressed but venom toxins are excellent effector candidates because they are target specific, potent and stable. However, the only toxins to be explored in mosquito paratransgenesis to date are scorpine and mutated phospholipase A2. To enhance the scope, effectiveness and durability of paratransgenesis, an expanded arsenal of effectors is required. This review discusses other potential toxin effectors for future paratransgenesis studies based on prior in vitro and in vivo antiparasitic and antiviral studies and highlights the need for further research and investment in this area. In terms of mosquito-borne diseases, paratransgenesis strategies have been developed to target Plasmodium. We postulate the potential to apply this principle to target arboviruses using antiviral toxin effectors.
Implications of successive blood feeding on Wolbachia-mediated dengue virus inhibition in Aedes aegypti mosquitoes
34529Rebecca M. Johnson, Mallery I. Breban, Braiya L. Nolan, et al., bioRxiv, 2025-02-21 10:22:32.
Dengue virus (DENV) is a mosquito-borne virus that poses a continued and increasing threat to public health. A promising strategy to mitigate the burden of DENV is introgression of the virus-inhibiting Wolbachia pipientis bacterium into Aedes aegypti populations in the field. While previous studies on Wolbachia-mediated virus inhibition have typically assessed viral replication following a single bloodmeal, the main vector of DENV, Ae. aegypti, feeds frequently, often biting multiple hosts per gonotrophic cycle and promptly attempting to refeed following egg laying. Previously, we demonstrated that successive blood feeding reduces the extrinsic incubation period (EIP) and shortens the time it takes for a mosquito to be able to transmit viruses to a new host. With this in mind, we investigated the impact of successive blood meals on DENV serotype 2 (DENV-2) in Ae. aegypti in the presence or absence of Wolbachia (wAlbB and wMelM). We found that both WT and Wolbachia transinfected had increased DENV-2 dissemination 7 days post-infection as well as higher body titers of DENV-2 in the double-fed groups. Using these empirical data in a binomial regression model, we estimated that successive feeding increased the probability of WT and Wolbachia transinfected mosquitoes surviving the EIP. When we estimated the odds of surviving the EIP for mosquitoes with Wolbachia relative to WT mosquitoes, successive feeding increased the chances of WT mosquitoes surviving the EIP more than in mosquitoes with Wolbachia, indicating a strong inhibitory effect of Wolbachia even in the context of natural frequent blood feeding behavior. Our work shows that mosquito feeding behavior should be considered when assessing the inhibitory effects of Wolbachia on DENV.
Suppression of Aedes aegypti may not affect sympatric Aedes albopictus populations: findings from two years of entomological surveillance in Singapore
34497Wong, W.J., Tan, C.H., Verkaik, M.G. et al., Scientific Reports, 15:2253. 2025-02-04 19:28:45.
Globally, multiple trials have successfully demonstrated the effectiveness of novel tools, such as the sterile and incompatible insect techniques, in suppressing Aedes aegypti populations. However, there is concern that Aedes albopictus, another arbovirus-competent vector, may occupy the niches vacated by Ae. aegypti in areas where these species occur in sympatry. Here we investigate these concerns within the context of a Wolbachia-based Ae. aegypti suppression programme in highly urban Singapore, where general mosquito management is sustained through environmental management. Using nationally representative and longitudinal Aedes surveillance data, we show (1) no consistent association of increase in Ae. albopictus abundance with Ae. aegypti population suppression within Wolbachia-Aedes release sites, and (2) no significant change in the vertical spatial distribution of Ae. albopictus in high-rise residential apartment blocks even after two years of Ae. aegypti suppression. Finally, we report that dengue viruses were less prevalent in field Ae. albopictus than in Ae. aegypti, which is consistent with previous findings that Ae. albopictus is a lesser vector than Ae. aegypti in Singapore. Together, these results indicate that suppression of Ae. aegypti in the community may not be directly associated with any increase of Ae. albopictus population or capacity. Nonetheless, the risk of increase in Ae. albopictus population is anticipated if the reduction in disease transmission leads to less aggressive source reduction efforts and environmental management for mosquito control.
Assessing Radiation-Induced Enzyme Activation in Aedes aegypti: Potential Challenges for SIT-Based Vector Management
34370Edvane Borges da Silva, Sloana Giesta Lemos Florêncio, Ademir Amaral, et al., Acta Tropica, 261. 2025-01-28 14:35:08.
This study characterizes the Aedes aegypti population from Fernando de Noronha Island, Pernambuco, Brazil, prior to implementing the Sterile Insect Technique (SIT). The main objective was to assess changes in glutathione S-transferase (GST) enzyme activity, previously linked to cypermethrin resistance in this population, in 2010. GST activity was measured in both male and female mosquitoes, mass-produced in the lab, after exposure to ionizing radiation. The population evaluation after six years showed complete susceptibility to cypermethrin, deltamethrin, and lambda-cyhalothrin, although GST activity remained altered, increasing further following irradiation (50% higher in irradiated males and 31% higher in irradiated females compared to non-irradiated controls). This stress response to gamma radiation suggests implications for the effectiveness and viability of sterile males, particularly when SIT is combined with chemical insecticides. These findings enhance our understanding of radiation's impact on metabolic responses of the sterile males and provide valuable insights for refining integrated control strategies in vector management programs.
Assessment of drive efficiency and resistance allele formation of a homing gene drive in the mosquito Aedes aegypti
34261Yang, X., Xu, X., Chen, Y. et al., Journal of Pest Science, 2025-01-14 09:57:33.
Aedes aegypti, known for transmitting viruses such as dengue, Zika and yellow fever, poses a significant public health threat. Conventional insecticides give rise to a range of issues, including ecological contamination and insect resistance. Hence, there is a pressing demand for environmentally-friendly, safer and more efficacious strategies for mosquito control. With the rapid advancement of the CRISPR/Cas9 system in gene function exploration and pest population control, substantial progress has been achieved in utilizing CRISPR/Cas9-based gene drive systems across various mosquito species. Only a few studies on gene drive technology have been conducted in Ae. aegypti. In this study, we constructed two complete drives for Ae. aegypti with different Cas9 promoters, each targeting kmo. Our drive based on PubCas9 had limited activity, but one with ExuCas9 exhibited super-Mendelian inheritance rates of approximately 60%. We observed low but detectable somatic activity of the drive and no evidence of maternally deposited Cas9. Germline resistance allele formation rates were similar to drive conversion rates, but most wild-type alleles in the germline remained uncut. Injections into the ExuCas9 drive line had 100% knockout efficiency among surviving offspring at three separate target genes. These results support the development and application of novel genetic pest control technologies aimed at combating Ae. aegypti.
Recommendations for Implementing Innovative Technologies to Control Aedes aegypti: Population Suppression Using a Combination of the Incompatible and Sterile Insect Techniques (IIT-SIT), Based on the Mexican Experience/Initiative
34247Martín-Park, A., Contreras-Perera, Y., et al., Insects, 15:987. 2025-01-13 11:41:22.
The future of Aedes aegypti control emphasizes the transition from traditional insecticides toward more sustainable and multisectoral integrated strategies, like using Wolbachia-carrying mosquitoes for population suppression or replacement. We reviewed the integration of the successful Mexican initiative, “Mosquitos Buenos”, with the key challenges outlined in the PAHO guidelines for incorporating innovative approaches into vector control programs. These challenges include establishing essential infrastructure, training personnel, managing field operations, and fostering community support. Our experience provides critical evidence to support the strategic National Plan for implementing and integrating IIT-SIT technologies to control Ae. aegypti and dengue. Furthermore, this experience serves as a foundation for other countries in the region interested in adopting these technologies. It underscores the importance of strategic planning, multisectoral collaboration, continuous evaluation, and scaling up innovative tools to ensure their long-term effectiveness and sustainability in urban areas where Aedes vectors and the diseases they transmit are endemic.
Variable effects of transient Wolbachia infections on alphaviruses in Aedes aegypti
33429Brittany L. Dodson, Sujit Pujhari, et al., PLoS Neglected Tropical Diseases, 2024-11-05 11:32:58.
Wolbachia pipientis (= Wolbachia) has promise as a tool to suppress virus transmission by Aedes aegypti mosquitoes. However, Wolbachia can have variable effects on mosquito-borne viruses. This variation remains poorly characterized, yet the multimodal effects of Wolbachia on diverse pathogens could have important implications for public health. Here, we examine the effects of transient somatic infection with two strains of Wolbachia (wAlbB and wMel) on the alphaviruses Sindbis virus (SINV), O’nyong-nyong virus (ONNV), and Mayaro virus (MAYV) in Ae. aegypti. We found variable effects of Wolbachia including enhancement and suppression of viral infections, with some effects depending on Wolbachia strain. Both wAlbB- and wMel-infected mosquitoes showed enhancement of SINV infection rates one week post-infection, with wAlbB-infected mosquitoes also having higher viral titers than controls. Infection rates with ONNV were low across all treatments and no significant effects of Wolbachia were observed. The effects of Wolbachia on MAYV infections were strikingly strain-specific; wMel strongly blocked MAYV infections and suppressed viral titers, while wAlbB had more modest effects. The variable effects of Wolbachia on vector competence underscore the importance of further research into how this bacterium impacts the virome of wild mosquitoes including the emergent human pathogens they transmit.
Evaluation of Wolbachia infection in Aedes aegypti suggests low prevalence and highly heterogeneous distribution in Medellín, Colombia
32509rley Calle-Tobón, Raúl Rojo-Ospina, et al., Acta Tropica, 260. 2024-10-08 09:19:14.
Dengue virus, transmitted mainly by Aedes aegypti mosquitoes, is a significant public health challenge in tropical and subtropical countries, with an incidence that is growing at an alarming rate. The release of Wolbachia-carrying mosquitoes has been suggested as a strategy to reduce the incidence of multiple arboviruses. In Medellín, Colombia, large-scale releases of Wolbachia-infected Ae. aegypti mosquitoes were performed between 2017 and 2022 by the World Mosquito Program to facilitate population replacement. In this study, we evaluated the prevalence and distribution of Wolbachia-infected Ae. aegypti two years after completion of these releases. We conducted the sampling across 19 communes in Medellín, using 416 ovitraps to collect Ae. aegypti eggs from epidemiological weeks 26 to 41 in 2023. Upon hatching the collected eggs, we identified and pooled adult female Ae. aegypti for DNA extraction. Subsequently, we conducted PCR assays for the detection of Wolbachia infection in these mosquitoes. We used maximum likelihood estimation (MLE) and Bayesian methods to estimate the prevalence of Wolbachia infection, while using QGIS to analyze spatial distribution of infection in the region. A total of 774 female Ae. aegypti mosquitoes from 182 pools were evaluated. We detected Wolbachia in 33.5 % of pools, with an estimated individual minimum infection rate of 9.5 % and a maximum of 33.2 %. The prevalence varied significantly across communes, with the highest rates observed in the northeastern and southwestern areas. Spatial analysis revealed a highly heterogeneous island-like distribution of Wolbachia across Medellín with a few hotspots. The observed Wolbachia prevalence in this work was lower than previously reported. We suspect a decline in the prevalence of Wolbachia-infected Ae. aegypti mosquitoes in Medellín following the completion of their release.
Assessment of drive efficiency and resistance allele formation of a homing gene drive in the mosquito Aedes aegypti
32128Xiaozhen Yang, Xuejiao Xu, et al., bioRxiv, 2024-10-03 09:34:32.
Aedes aegypti, known for transmitting viruses such as dengue, zika, and yellow fever, poses a significant public health threat. Conventional insecticides give rise to a range of issues, including ecological contamination and insect resistance. Hence, there is a pressing demand for environmentally friendly, safer, and more efficacious strategies for mosquito control. With the rapid advancement of the CRISPR/Cas9 system in gene function exploration and pest population control, substantial progress has been achieved in utilizing CRISPR/Cas9-based gene drive systems across various mosquito species. Only a few studies on gene drive technology have been conducted in A. aegypti. In this study, we constructed two complete drives for A. aegypti with different Cas9 promoters, each targeting kmo. Our drive based on Pub-Cas9 had limited activity, but one with exu-Cas9 exhibited super-Mendelian inheritance rates of approximately 60%. We observed low but detectable somatic activity of the drive and no evidence of maternally deposited Cas9. Germline resistance allele formation rates were similar to drive conversion rates, but most wild-type alleles in the germline remained uncut. Injections into the exu-Cas9 drive line had 100% knockout efficiency among surviving offspring at three separate target genes. These results support the development and application of novel genetic pest control technologies aimed at combating A. aegypti.
Wolbachia infection in Aedes aegypti does not affect its vectorial capacity for Dirofilaria immitis
32124Shirozu, T., Regilme, M.A.F., Ote, M. et al., Scientific Reports, 14. 2024-10-03 09:25:30.
Mosquito-borne diseases such as dengue and filariasis are a growing public health concern in endemic countries. Biological approaches, such as the trans-infection of Wolbachia pipientis in mosquitoes, are an alternative vector control strategy, especially for arthropod-borne viruses such as dengue. In the present study, the effect of Wolbachia (wMel strain) on the vectorial capacity of Aedes aegypti for Dirofilaria immitis was studied. Our results showed that Wolbachia does not affect the phenotype of mosquito survival or the prevalence, number, and molting rate of third-stage larvae in both susceptible and resistant strains of Ae. aegypti. RNA-seq analysis of Malpighian tubules at 2 days post-infection with D. immitis showed the differentially expressed genes (DEGs) with and without wMel infection. No characteristic immune-related gene expression patterns were observed among the DEGs. No significant change in the amount of Wolbachia was observed in the Ae. aegypti after D. immitis infection. Our results suggest that infection of D. immitis in Ae. aegypti populations will not interfere with Wolbachia-based vector control strategies in dengue-endemic areas where cases of D. immitis are present. This study demonstrated the veterinary medical validity of a dengue control program using Wolbachia.
Current status of the sterile insect technique for the suppression of mosquito populations on a global scale
32019Bouyer, J., Infectious Diseases of Poverty, 13. 2024-10-01 16:03:32.
The World Health Organization (WHO) has emphasized the urgent need for alternative strategies to chemical insecticides for controlling mosquito populations, particularly the invasive Aedes species, which are known vectors of arboviruses. Among these alternative approaches, the sterile insect technique (SIT) is experiencing rapid development, with numerous pilot trials being conducted worldwide. This review aims to elucidate the principles of SIT and highlight the significant recent advancements that have facilitated its scalability. I also employ a phased conditional approach to categorize the progression of 39 projects, drawing on peer reviewed studies, press releases and direct communication with project managers. This review indicates that a substantial number of projects illustrate the efficacy of SIT in suppressing Aedes populations, with one project even demonstrating a reduction in dengue incidence. I offer several recommendations to mitigate potential failures and address the challenges of compensation and overcompensation when implementing SIT field trials. Furthermore, I examine the potential implications of male mating harassment on the effectiveness of SIT in reducing disease transmission. This comprehensive assessment underscores the promise of SIT as a viable strategy for mosquito control. The insights gained from these trials not only contribute to the understanding of SIT’s effectiveness but also highlight the importance of careful project management and ecological considerations in the pursuit of public health objectives.
10 myths and misconceptions around modified mosquitoes
31627Milliam Murigi, k24, 2024-09-23 21:32:42.
In the fight against mosquito-borne diseases, scientists have turned to groundbreaking genetic technologies to reduce disease transmission. However, Genetically Modified (GM) mosquitoes have raised concerns and sparked myths and misconceptions around it. Abraham Isah, OFAB Project officer, Nigeria demystifies them. There have been allegations that scientists have secret agendas, and that is why they’re pushing for the release of Genetically Modified (GM) mosquitoes. However, the truth, releasing GM is intended to control populations of disease-carrying mosquitoes, such as Aedes aegypti, which spread malaria, dengue, and Zika virus. These mosquitoes are engineered to either reduce the population or make it less capable of transmitting diseases. This approach has been thoroughly tested and regulated by authorities like the Environmental Protection Agency (EPA) and the World Health Organisation (WHO) to ensure safety and efficacy. The primary goal is to reduce disease burden and improve public health, not to impose a hidden agenda.
Mark–Release–Recapture Trial with Aedes albopictus (Diptera, Culicidae) Irradiated Males: Population Parameters and Climatic Factors
31590Amaro FIF, Soares P, Velo E, et al, Insects, 15. 2024-09-17 12:23:28.
Aedes albopictus mosquitoes spread arboviruses like dengue, Zika, or chikungunya. The Sterile Insect Technique (SIT) can be used as a prevention and control tool against Ae. albopictus populations. Mark–release–recapture (MRR) trials are fundamental to estimate the size of the wild population in target areas and to determine the dispersal capacity and survival of sterile males in open field conditions. Environmental conditions can affect the MRR trial’s results; thus, the influence of climatic factors on the first MRR trial with Ae. albopictus marked sterile males conducted in Portugal was analyzed. In October 2022, for three consecutive weeks at two different release points, 84,000 sterile males were released over 50 ha of the study area, in the municipality of Faro, Southern Portugal, and mosquitoes were recaptured by human landing collection (HLC) one, two, four, and six days after release. Distance travelled, daily survival, and life expectancy in the field were estimated for the released sterile males and the influence of climatic factors was analyzed. Despite no statistically significant association being found with humidity, temperature, and precipitation, it is crucial to plan MRRs, considering weather conditions for a more efficient application of the SIT in an integrated vector management program.
Effectiveness of Wolbachia-mediated sterility coupled with sterile insect technique to suppress adult Aedes aegypti populations in Singapore: a synthetic control study
31580Bansal, Somya, et al., The Lancet Planetary Health, 8:617-628. 2024-09-17 10:04:54.
In this synthetic control study, we conducted a large-scale, field trial of IIT-SIT targeting Aedes aegypti among high-rise public housing estates in Singapore, an equatorial city state. Routinely collected data from a large, nationwide surveillance system of 57 990 unique mosquito traps, combined with a high-dimensional set of anthropogenic and environmental confounders were collected to ascertain mosquito abundance and its key drivers. Four townships were selected as the intervention groups (approximate population size of 607 872 residents as of 2022), wherein interventions that combined ITT with SIT over the course of the study period were conducted. Townships were subject to releases of wAlbB-SG male A aegypti mosquitoes twice a week. Data were assessed over the course of epidemiological weeks (EWs), which provide the finest temporal resolution of recorded Wolbachia release schedule and mosquito abundance data. A novel synthetic control framework was then developed to account for the non-randomised and staggered adoption setting of the intervention across trial sectors to identify the direct suppressive effectiveness of IIT-SIT on female A aegypti populations, the spillover effects in non-release areas, and the effect of the intervention on other mosquito populations such as Aedes albopictus. Furthermore, we recalculated effectiveness in terms of calendar time, time since intervention, and over multiple sites to examine heterogeneities in IIT-SIT effectiveness. Between EW27 2018 and EW26 2022, Wolbachia releases were conducted across 117 sectors, of which 97 had sufficient trap data, which were collected between EW8 2019 and EW26 2022. We found that Wolbachia-based IIT-SIT reduced wild-type female A aegypti populations by a mean of 62·01% (95% CI 60·68 to 63·26) by 3 months, 78·40% (77·56 to 79·18) by 6 months, and 91·32% (90·95 to 91·66) by at least 18 months of releases. We also found a smaller but non-negligible spillover suppression effect that gradually increased over time (mean spillover intervention effectiveness 61·02% [95% CI 57·89 to 63·72] in adjacent, non-intervention sectors). Although no consistent change in A albopictus populations was seen across the four intervention townships after Wolbachia releases, the average intervention effectiveness on the A albopictus population across all release sectors was –25·80% (95% CI –30·93 to –21·05), which was driven by increases in two towns.
Bunyamwera Virus Infection of Wolbachia-Carrying Aedes aegypti Mosquitoes Reduces Wolbachia Density
31318Lefteri, D.A.; Rainey, S.M.; Murdochy, S.M.; Sinkins, S.P., Viruses, 16. 2024-09-03 15:42:46.
Wolbachia symbionts introduced into Aedes mosquitoes provide a highly effective dengue virus transmission control strategy, increasingly utilised in many countries in an attempt to reduce disease burden. Whilst highly effective against dengue and other positive-sense RNA viruses, it remains unclear how effective Wolbachia is against negative-sense RNA viruses. Therefore, the effect of Wolbachia on Bunyamwera virus (BUNV) infection in Aedes aegypti was investigated using wMel and wAlbB, two strains currently used in Wolbachia releases for dengue control, as well as wAu, a strain that typically persists at a high density and is an extremely efficient blocker of positive-sense viruses. Wolbachia was found to reduce BUNV infection in vitro but not in vivo. Instead, BUNV caused significant impacts on density of all three Wolbachia strains following infection of Ae. aegypti mosquitoes. The ability of Wolbachia to successfully persist within the mosquito and block virus transmission is partially dependent on its intracellular density. However, reduction in Wolbachia density was not observed in offspring of infected mothers. This could be due in part to a lack of transovarial transmission of BUNV observed. The results highlight the importance of understanding the complex interactions between multiple arboviruses, mosquitoes and Wolbachia in natural environments, the impact this can have on maintaining protection against diseases, and the necessity for monitoring Wolbachia prevalence at release sites.
Excess Lipids Keep Dengue at Bay
31315Shelby Bradford, The Scientist, 2024-09-03 15:36:36.
The Aedes aegypti mosquito can transmit dengue virus; however, infection with endosymbiotic bacteria from the Wolbachia genus reduces viral transmission from these insects. Consequently, Wolbachia-infected mosquitos are one biocontrol agent used in areas with endemic dengue cases. “We are trying to go backwards now, because the intervention works, but we don’t know how,” said Robson Loterio, a microbiologist at the Burnet Institute and author of a paper published in mBio exploring the mechanism of Wolbachia’s antiviral activity. The findings can help researchers prevent viral escape from this biocontrol method. Loterio and his team infected A. aegypti cells with antiviral Wolbachia strains. Using transmission electron microscopy and confocal microscopy, they showed that these bacteria predominantly clustered at the cell’s endoplasmic reticulum (ER). The ER produces molecules used in lipid droplet synthesis. Since both Wolbachia and dengue rely on lipid metabolism, the team investigated the effect of Wolbachia on droplet formation during viral infection by comparing antiviral Wolbachia-infected cells to Wolbachia-free cells. Lipid droplets accumulated in both types of cells, but cells with the bacteria had more lipid accumulation.
Optimizing and synchronizing Aedes aegypti colony for Sterile Insect Technique application: Egg hatching, larval development, and adult emergence rate
31193Jennifer Thieme Castellon, Solomon Kibret Birhanie, Ale Macias, Rubi Casas, Jacob Hans, Michelle Q. Brown, Acta Tropica, 259. 2024-08-27 08:24:10.
Mosquito Sterile Insect Technique (SIT) programs can be developed in smaller agencies through synchronization of the colony development to take advantage of the natural male early emergence. This paper examined key aspects of Ae. aegypti colony synchronization work, including egg hatching, larval development, and adult emergence to produce sufficient numbers of adult male mosquitoes within a specific timeframe for irradiation and release. Our data indicated that a relatively low percentage of males are required for colony propagation. Additional results highlighted that fresher Ae. aegypti eggs could yield as high as a 93 % hatching success than older eggs when placed under vacuum pressure in yeast infused water for 1.5 h. Eggs that were one-month old hatched (93 %) better than older eggs (0–32 %). A higher egg density in the hatching flask was correlated to a lower hatch rate, and higher larval density was related to unsynchronized pupae and delayed adult emergence. By keeping Ae. aegypti larvae at reasonable density, over 95 % of adults emerged on the first two days of emergence – indicating a high synchronicity. A standardized colony maintenance protocol therefore renders a synchronized larval development and adult male emergence which are critical in SIT programs.
A comprehensive review of Wolbachia-mediated mechanisms to control dengue virus transmission in Aedes aegypti through innate immune pathways
31172Iqra Mushtaq, Muhammad Sajjad Sarwar, Iqra Munzoor, Viral Immunology, 15. 2024-08-25 20:04:21.
The Dengue virus (DENV), primarily spread by Aedes aegypti and also by Aedes albopictus in some regions, poses significant global health risks. Alternative techniques are urgently needed because the current control mechanisms are insufficient to reduce the transmission of DENV. Introducing Wolbachia pipientis into Ae. aegypti inhibits DENV transmission, however, the underlying mechanisms are still poorly understood. Innate immune effector upregulation, the regulation of autophagy, and intracellular competition between Wolbachia and DENV for lipids are among the theories for the mechanism of inhibition. Furthermore, mainly three immune pathways Toll, IMD, and JAK/STAT are involved in the host for the suppression of the virus. These pathways are activated by Wolbachia and DENV in the host and are responsible for the upregulation and downregulation of many genes in mosquitoes, which ultimately reduces the titer of the DENV in the host. The functioning of these immune pathways depends upon the Wolbachia, host, and virus interaction. Here, we summarize the current understanding of DENV recognition by the Ae. aegypti’s immune system, aiming to create a comprehensive picture of our knowledge. Additionally, we investigated how Wolbachia regulates the activation of multiple genes associated with immune priming for the reduction of DENV.
Revisiting Wolbachia detections: Old and new issues in Aedes aegypti mosquitoes and other insects
30882Perran A. Ross, Ary A. Hoffmann, Ecology and Evolution, 14. 2024-07-07 21:12:05.
Wolbachia continue to be reported in species previously thought to lack them, particularly Aedes aegypti mosquitoes. The presence of Wolbachia in this arbovirus vector is considered important because releases of mosquitoes with transinfected Wolbachia are being used around the world to suppress pathogen transmission and these efforts depend on a lack of Wolbachia in natural populations of this species. We previously assessed papers reporting Wolbachia in natural populations of Ae. aegypti and found little evidence that seemed convincing. However, since our review, more and more papers are emerging on Wolbachia detections in this species. Our purpose here is to evaluate these papers within the context of criteria we previously established but also new criteria that include the absence of releases of transinfections within the local areas being sampled which has contaminated natural populations in at least one case where novel detections have been reported. We also address the broader issue of Wolbachia detection in other insects where similar issues may arise which can affect overall estimates of this endosymbiont more generally. We note continuing shortcomings in papers purporting to find natural Wolbachia in Ae. aegypti which are applicable to other insects as well.
The race against time to defeat mosquito-borne diseases
30858Michael Peel, Financial Times, 2024-06-28 15:51:06.
Deep in the bowels of Imperial College London’s main campus is a facility known as the insectary. The journey to it, via basement corridors and an entrance that sounds an alarm upon opening, feels like something out of a horror film. Beyond two sets of double doors lies the reason for the security: thousands of the Anopheles mosquito that has long been humanity’s deadliest animal threat. The insects in these temperature-controlled chambers are central to pioneering efforts to use genetic engineering to stop them passing on life-threatening malaria. Federica Bernardini, a research associate, places a hand close to the white mesh sides of a box housing the biting bugs. “I am not going to put it there for long,” Bernardini says, quickly pulling back from the tiny creatures. The Imperial work is part of a global struggle against the intensifying threat of mosquitoes and the destructive pathogens they carry. The first malaria vaccination campaign is being rolled out this year, while researchers are exploring ways to stem disease that are both ingenious and — in the case of genetic engineering — controversial to some. It is part of a wider public health battle against various infectious diseases that have surged in recent years due to environmental change, the Covid-19 pandemic and other factors. The mosquito campaign is a race against the clock. The insects are becoming more resistant to traditional prevention methods, while the climate crisis has opened up new regions where they can thrive.
Comparing the long-term persistence of different Wolbachia strains after the release of bacteria-carrying mosquitoes
29563Jose L. Orozco-Gonzales, Antone dos Santos Benedito, Daiver Cardona-Salgado et al., Mathematical Biosciences, 372. 2024-04-25 17:59:21.
This paper proposes a bidimensional modeling framework for Wolbachia invasion, assuming imperfect maternal transmission, incomplete cytoplasmic incompatibility, and direct infection loss due to thermal stress. Our model adapts to various Wolbachia strains and retains all properties of higher-dimensional models. The conditions for the durable coexistence of Wolbachia-carrying and wild mosquitoes are expressed using the model’s parameters in a compact closed form. When the Wolbachia bacterium is locally established, the size of the remanent wild population can be assessed by a direct formula derived from the model. The model was tested for four Wolbachia strains undergoing laboratory and field trials to control mosquito-borne diseases: wMel, wMelPop, wAlbB, and wAu. As all these bacterial strains affect the individual fitness of mosquito hosts differently and exhibit different levels of resistance to temperature variations, the model helped to conclude that: (1) the wMel strain spreads faster in wild mosquito populations; (2) the wMelPop exhibits lower resilience but also guarantees the smallest size of the remanent wild population; (3) the wAlbB strain performs better at higher ambient temperatures than others; (4) the wAu strain is not sustainable and cannot persist in the wild mosquito population despite its resistance to high temperatures.
A naturally isolated symbiotic bacterium suppresses flavivirus transmission by Aedes mosquitoes
29561Liming Zhang et al., Science, 384. 2024-04-25 17:51:54.
Flavivirus diseases are increasing in incidence and prevalence owing to the urban proclivities of its Aedes mosquito vector species. Extirpation of mosquitoes is considered key for the control of several human diseases but often involves toxic chemicals that prompt mosquito resistance. As some biocontrol alternatives look promising in malaria campaigns, Zhang et al. examined the microbiota of Aedes mosquitoes for potential agents to control dengue and Zika virus transmission. The authors isolated a bacterium called Rosenbergiella_YN46 in Aedes albopictus mosquitos. The bacterium was fed to caged mosquitoes to establish stable gut infections, and it was found to prevent the insects from being infected by viruses and blocked viral transmission to mice.
Economic optimization of Wolbachia-infected Aedes aegypti release to prevent dengue
29104Hollingsworth BD, Cho C, Vella M, Roh H, Sass J, Lloyd AL, Brown ZS., Pest Management Science, 2024-04-16 09:30:09.
Dengue virus, primarily transmitted by the Aedes aegypti mosquito, is a major public health concern affecting ≈3.83 billion people worldwide. Recent releases of Wolbachia-transinfected Ae. aegypti in several cities worldwide have shown that it can reduce dengue transmission. However, these releases are costly, and, to date, no framework has been proposed for determining economically optimal release strategies that account for both costs associated with disease risk and releases. We present a flexible stochastic dynamic programming framework for determining optimal release schedules for Wolbachia-transinfected mosquitoes that balances the cost of dengue infection with the costs of rearing and releasing transinfected mosquitoes. Using an ordinary differential equation model of Wolbachia and dengue in a hypothetical city loosely describing areas at risk of new dengue epidemics, we determined that an all-or-nothing release strategy that quickly brings Wolbachia to fixation is often the optimal solution. Based on this, we examined the optimal facility size, finding that it was inelastic with respect to the mosquito population size, with a 100% increase in population size resulting in a 50-67% increase in optimal facility size. Furthermore, we found that these results are robust to mosquito life-history parameters and are mostly determined by the mosquito population size and the fitness costs associated with Wolbachia. These results reinforce that Wolbachia-transinfected mosquitoes can reduce the cost of dengue epidemics. Furthermore, they emphasize the importance of determining the size of the target population and fitness costs associated with Wolbachia before releases occur.
The Perpetual Vector Mosquito Threat and Its Eco-Friendly Nemeses
29088Miranda, L.S.; Rudd, S.R.; Mena, O.; Hudspeth, P.E.; Barboza-Corona, J.E.; Park, H.-W.; Bideshi, D.K., Biology, 13:182. 2024-04-04 09:42:02.
Aedes, Culex, and Anopheles mosquitoes are the most prolific arthropod vectors of viral and parasitic agents of debilitating and lethal diseases in humans and animals. Despite some success in integrated pest management programs to control vectors, mosquito-borne diseases, such as dengue and dengue hemorrhagic fever, yellow fever, chikungunya, West Nile, and Zika, and parasitic diseases, such as malaria, lymphatic filariasis, and river blindness, continue to threaten the health and well-being of half the world’s population, many of whom live in economically and medically challenged societies. The perpetual problem inflicted by vector-borne diseases is compounded by the selection for resistance to synthetic pesticides, globalization, and climate change. The latter appears to be the most significant factor implicated in the geographic expansion of mosquitoes. Here, we present a review of these challenges and highlight traditional vector control strategies that employ synthetic pesticides, and “green” eco-friendly technologies that include SIT, IIT, RIDL, CRISPR/Cas9/Cas13 gene drive systems, and biological control, with an emphasis on Lysinibacillus sphaericus and Bacillus thuringiensis subsp. israelensis (Bti).
Detection and quantification of natural Wolbachia in Aedes aegypti in Metropolitan Manila, Philippines using locally designed primers
29084Reyes JIL, Suzuki T, Suzuki Y, Watanabe K., Frontiers in Cellular and Infection Microbiology, 2024-04-04 09:23:33.
The Philippines bears health and economic burden caused by high dengue cases annually. Presently, the Philippines still lack an effective and sustainable vector management. The use of Wolbachia, a maternally transmitted bacterium, that mitigate arbovirus transmission has been recommended. Cytoplasmic incompatibility and viral blocking, two characteristics that make Wolbachia suitable for vector control, depend on infection prevalence and density. There are no current Wolbachia release programs in the Philippines, and studies regarding the safety of this intervention. Here, we screened for Wolbachia in Aedes aegypti collected from Metropolitan Manila, Philippines. We designed location-specific primers for qPCR to test whether this improved Wolbachia detection in Ae. aegypti. We explored if host sex and Wolbachia strain could be potential factors affecting Wolbachia density.
Monitoring Aedes populations for arboviruses, Wolbachia, insecticide resistance and its mechanisms in various agroecosystems in Benin
29064S. Ateutchia-Ngouanet, F. Nanfack-Minkeu, K. Mavridis, S. Wanji, M. Demanou, J. Vontas, R. Djouaka, Acta Tropica, 253. 2024-04-02 11:34:55.
The susceptibility of arbovirus vectors to insecticides and the microbiome of Aedes species are understudied in Benin.
Wolbachia strain wAlbB shows favourable characteristics for dengue control use in Aedes aegypti from Burkina Faso
29041Maria Vittoria Mancini, Shivan M. Murdochy, Etienne Bilgo, Thomas H. Ant, Daniel Gingell, Edounou Jacques Gnambani, Anna-Bella Failloux, Abdoulaye Diabate, Steven P. Sinkins, Environmental Microbiology, 26. 2024-03-19 16:46:34.
Dengue represents an increasing public health burden worldwide.
Alpha-mannosidase-2 modulates arbovirus infection in a pathogen- and Wolbachia-specific manner in Aedes aegypti mosquitoes
29035Nadya Urakova, Renuka E. Joseph, Allyn Huntsinger, Vanessa M. Macias, Matthew J. Jones, Leah T. Sigle, Ming Li, Omar S. Akbari, Zhiyong Xi, Konstantinos Lymperopoulos, Richard T. Sayre, Elizabeth A. McGraw, Jason L. Rasgon, Insect Molecular Biology, 2024-03-19 15:50:02.
Multiple Wolbachia strains can block pathogen infection, replication and/or transmission in Aedes aegypti mosquitoes under both laboratory and field conditions.
Brazil’s record dengue surge: why a vaccine campaign is unlikely to stop it
29023Mariana Lenharo, Nature, 2024-03-19 12:55:41.
A vaccine shortage and persistent sanitation problems threaten the success of the world’s first public vaccination campaign against dengue virus.
Acceptability of emergent Aedes aegypti vector control methods in Ponce, Puerto Rico: A qualitative assessment
29010Pérez-Guerra CL, Rosado-Santiago C, Ramos SA, Marrero-Santos KM, González-Zeno G, Partridge SK, et al., PLoS Global Public Health, 2024-03-11 13:41:04.
Aedes aegypti control has been fraught with challenges in Puerto Rico. The government has implemented commonly used vector control methods, but arboviral epidemics still occur. It is necessary to explore new Ae. aegypti control methods. This study aimed to understand the perceptions of community members in Ponce, Puerto Rico about emergent and traditional Ae. aegypti vector control methods and determine their acceptability and support for these methods. We identified the type of information needed to increase support for emergent vector control methods, and the preferred strategies to disseminate this information. Four group discussions were conducted with a total of 32 participants representing eight of the 14 clusters participating in the Communities Organized for the Prevention of Arboviruses (COPA), a project designed to mobilize communities in Ponce, Puerto Rico to prevent diseases transmitted by mosquitoes. Group discussions began with an overview of different methods used for controlling Ae. aegypti mosquitoes. These overviews facilitated participant understanding of the mosquito control methods presented. Use of source reduction, autocidal gravid ovitraps (AGO), and manual application of larvicide for arboviral mosquito control received support from almost all participants. Vector control methods that use more familiar techniques in Puerto Rico such as truck-mounted larvicide spraying (TMLS) and insecticide residual spraying received support from most participants. More than half of participants supported the use of emergent mosquito control methods including Wolbachia suppression, Wolbachia replacement, or genetically modified mosquitoes (GMM). Participants preferred to receive vector control information through house-to-house visits with the distribution of written materials, followed by dissemination of information through traditional (i.e., radio, television) and social media. The detailed information resulting from this study was used to develop messages for a communications campaign to garner future community support. Community acceptance and support are critical for the success of vector control programs using emergent mosquito control methods.
Efficacy of Wolbachia-based mosquito control: Predictions of a spatially discrete mathematical model
29008David Dye, John W. Cain, PLoS One, 19. 2024-03-11 12:43:55.
Wolbachia is an endosymbiont bacterium present in many insect species. When Wolbachia-carrying male Aedes aegypti mosquitoes mate with non-carrier females, their embryos are not viable due to cytoplasmic incompatibility. This phenomenon has been exploited successfully for the purpose of controlling mosquito populations and the spread of mosquito-borne illnesses: Wolbachia carriers are bred and released into the environment. Because Wolbachia is not harmful to humans, this method of mosquito control is regarded as a safer alternative to pesticide spraying. In this article, we introduce a mathematical framework for exploring (i) whether a one-time release of Wolbachia carriers can elicit a sustained presence of carriers near the release site, and (ii) the extent to which spatial propagation of carriers may allow them to establish fixation in other territories. While some prior studies have formulated mosquito dispersal models using advection-reaction-diffusion PDEs, the predictive power of such models requires careful ecological mapping: advection and diffusion coefficients exhibit significant spatial dependence due to heterogeneity of resources and topography. Here, we adopt a courser-grained view, regarding the environment as a network of discrete, diffusively-coupled “habitats”—distinct zones of high mosquito density such as stagnant ponds. We extend two previously published single-habitat mosquito models to multiple habitats, and calculate rates of migration between pairs of habitats using dispersal kernels. Our primary results are quantitative estimates regarding how the success of carrier fixation in one or more habitats is determined by: the number of carriers released, sizes of habitats, distances between habitats, and the rate of migration between habitats. Besides yielding sensible and potentially useful predictions regarding the success of Wolbachia-based control, our framework applies to other approaches (e.g., gene drives) and contexts beyond the realm of insect pest control.
Aedes aegypti Controls Ae. aegypti: SIT and IIT—An Overview
29003Robert L. Aldridge; Seth Gibson; Kenneth J. Linthicum, Journal of the American Mosquito Control Association, 20:32-49. 2024-03-11 12:34:19.
The sterile insect technique (SIT) and the incompatible insect technique (IIT) are emerging and potentially revolutionary tools for controlling Aedes aegypti (L.), a prominent worldwide mosquito vector threat to humans that is notoriously difficult to reduce or eliminate in intervention areas using traditional integrated vector management (IVM) approaches. Here we provide an overview of the discovery, development, and application of SIT and IIT to Ae. aegypti control, and innovations and advances in technology, including transgenics, that could elevate these techniques to a worldwide sustainable solution to Ae. aegypti when combined with other IVM practices.
DENV-1 Titer Impacts Viral Blocking in wMel Aedes aegypti with Brazilian Genetic Background
28991Corrêa-Antônio, Jessica, Mariana R. David, Dinair Couto-Lima, Gabriela Azambuja Garcia, Milan S. G. Keirsebelik, Rafael Maciel-de-Freitas, and Márcio Galvão Pavan., Viruses, 16. 2024-03-11 10:08:24.
Several countries have been using Wolbachia deployments to replace highly competent native Aedes aegypti populations with Wolbachia-carrying mosquitoes with lower susceptibility to arboviruses such as dengue, Zika, and chikungunya. In Rio de Janeiro, Wolbachia deployments started in 2015 and still present a moderate introgression with a modest reduction in dengue cases in humans (38%). Here, we evaluated the vector competence of wild-type and wMel-infected Ae. aegypti with a Brazilian genetic background to investigate whether virus leakage could contribute to the observed outcomes in Brazil. We collected the specimens in three areas of Rio de Janeiro with distinct frequencies of mosquitoes with wMel strain and two areas with wild Ae. aegypti. The mosquitoes were orally exposed to two titers of DENV-1 and the saliva of DENV-1-infected Ae. aegypti was microinjected into wMel-free mosquitoes to check their infectivity. When infected with the high DENV-1 titer, the presence of wMel did not avoid viral infection in mosquitoes’ bodies and saliva but DENV-1-infected wMel mosquitoes produced lower viral loads than wMel-free mosquitoes. On the other hand, wMel mosquitoes infected with the low DENV-1 titer were less susceptible to virus infection than wMel-free mosquitoes, although once infected, wMel and wMel-free mosquitoes exhibited similar viral loads in the body and the saliva. Our results showed viral leakage in 60% of the saliva of wMel mosquitoes with Brazilian background; thus, sustained surveillance is imperative to monitor the presence of other circulating DENV-1 strains capable of overcoming the Wolbachia blocking phenotype, enabling timely implementation of action plans.
Mosquito Control releases over 100K sterile male mosquitos to combat Aedes aegypti population
28978NBC2 News, 2024-03-05 14:41:50.
Mosquito Control releases over 100K sterile male mosquitos to combat Aedes aegypti population
Gene Drive Systems To Control Aedes Aegypti Mosquitoes Make Headway
28966Joshua Ang, Outreach Network for Gene Drive Research, 2024-03-05 13:15:42.
Aedes aegypti mosquitoes are known vectors of several diseases, including dengue, chikungunya, yellow fever, and Zika, which impact millions of people worldwide each year. The effectiveness of existing insecticide-based methods to control this mosquito is threatened by growing insecticide resistance, underscoring the need to develop new approaches. The advent of CRISPR/Cas9 genome editing has reshaped the research and development landscape of new potential vector control tools, leading researchers to explore novel approaches, such as gene drive technologies. In the past few years, gene drive technologies have gained remarkable traction, particularly for their success in controlling major malaria mosquito vectors in laboratory settings. A gene drive is able to bias its own inheritance, facilitating the spread of a specific trait through a target population. This super-Mendelian pattern of propagation makes gene drive technology an efficient and cost-effective potential new method to control mosquitoes that transmit disease.
Introduction of Aedes aegypti mosquitoes carrying wAlbB Wolbachia sharply decreases dengue incidence in disease hotspots
28927AA Hoffmann, NW Ahmad, WM Keong, CY Ling, NA Ahmad, N. Golding, N. Tierney, J. Jelip, PW Putit, N Mohktar, SS Sandhu, LS Ming, et al., iScience, 2024-02-27 16:48:03.
Partial replacement of resident Aedes aegypti mosquitoes with introduced mosquitoes carrying certain strains of inherited Wolbachia symbionts can result in transmission blocking of dengue and other viruses of public health importance. Wolbachia strain wAlbB is an effective transmission blocker and stable at high temperatures, making it particularly suitable for hot tropical climates. Following trial field releases in Malaysia, releases using wAlbB Ae. aegypti have become operationalized by the Malaysian health authorities. We report here on an average reduction in dengue fever of 62.4% (confidence intervals 50–71%) in 20 releases sites when compared to 76 control sites in high-rise residential areas. Importantly the level of dengue reduction increased with Wolbachia frequency, with 75.8% reduction (61–87%) estimated at 100% Wolbachia frequency. These findings indicate large impacts of wAlbB Wolbachia invasions on dengue fever incidence in an operational setting, with incidence expected to further decrease as wider areas are invaded.
New gene-editing tools may help wipe out mosquito-borne diseases
28859Greg Allen, NPR, 2024-01-30 17:05:14.
In the age-old war of human versus mosquitoes, the bugs have been winning. At least 700,000 people die every year from mosquito-borne diseases such as malaria, dengue, West Nile and yellow fever. Global trade and climate change have helped disease-carrying species become established in places like Florida, California, and Texas. In parts of the U.S., dengue is now a persistent problem. Last year, for the first time in decades, Florida and Texas reported locally-acquired malaria cases. Maryland also had a case. But by using bioengineering, scientists have developed tools they believe may help control and possibly eradicate mosquitoes that carry dengue, malaria and other diseases. Andrea Leal, the head of mosquito control in the Florida Keys says, "The good news is we've got these emerging technologies that show great promise in reducing Aedes aegypti mosquitoes."
A multiplexed, confinable CRISPR/Cas9 gene drive can propagate in caged Aedes aegypti populations
28857Anderson, M.A.E., Gonzalez, E., Edgington, M.P. et al., Nature Communications, 15. 2024-01-30 16:38:51.
Aedes aegypti is the main vector of several major pathogens including dengue, Zika and chikungunya viruses. Classical mosquito control strategies utilizing insecticides are threatened by rising resistance. This has stimulated interest in new genetic systems such as gene drivesHere, we test the regulatory sequences from the Ae. aegypti benign gonial cell neoplasm (bgcn) homolog to express Cas9 and a separate multiplexing sgRNA-expressing cassette inserted into the Ae. aegypti kynurenine 3-monooxygenase (kmo) gene. When combined, these two elements provide highly effective germline cutting at the kmo locus and act as a gene drive. Our target genetic element drives through a cage trial population such that carrier frequency of the element increases from 50% to up to 89% of the population despite significant fitness costs to kmo insertions. Deep sequencing suggests that the multiplexing design could mitigate resistance allele formation in our gene drive system.
Maxizyme-mediated suppression of chikungunya virus replication and transmission in transgenic Aedes aegypti mosquitoes
28819Mishra P, Balaraman V, Fraser Jr. M, Frontiers in Microbiology, 14. 2024-01-23 14:40:52.
Chikungunya virus (CHIKV) is an emerging mosquito-borne pathogen of significant public health importance. There are currently no prophylactic vaccines or therapeutics available to control CHIKV. One approach to arbovirus control that has been proposed is the replacement of transmission-competent mosquitoes with those that are refractory to virus infection. Several transgene effectors are being examined as potentially useful for this population replacement approach. We previously demonstrated the successful use of hammerhead ribozymes (hRzs) as an antiviral effector transgene to control CHIKV infection of, and transmission by, Aedes mosquitoes. In this report we examine a maxizyme approach to enhance the catalytic activity and prevent virus mutants from escaping these ribozymes. We designed a maxizyme containing minimized (monomer) versions of two hRzs we previously demonstrated to be the most effective in CHIKV suppression. Three versions of CHIKV maxizyme were designed: Active (Mz), inactive (ΔMz), and a connected CHIKV maxizyme (cMz). The maxizymes with their expression units (Ae-tRNA val promoter and its termination signal) were incorporated into lentivirus vectors with selection and visualization markers. Following transformation, selection, and single-cell sorting of Vero cells, clonal cell populations were infected with CHIKV at 0.05 and 0.5 MOI, and virus suppression was assessed using TCID50-IFA, RT-qPCR, and caspase-3 assays. Five transgenic mosquito lines expressing cMz were generated and transgene insertion sites were confirmed by splinkerette PCR. Our results demonstrate that Vero cell clones expressing Mz exhibited complete inhibition of CHIKV replication compared to their respective inactive control version or the two parent hRzs. Upon oral challenge of transgenic mosquitoes with CHIKV, three out of the five lines were completely refractory to CHIKV infection, and all five lines tested negative for salivary transmission. Altogether, this study demonstrates that maxizymes can provide a higher catalytic activity and viral suppression than hRzs.
Mosquito makeover: Tahiti’s groundbreaking solution to disease
28823Atutahi Potaka-Dewes, Pacific Media Network, 2024-01-19 14:49:43.
Mosquitoes are responsible for transmitting such diseases as dengue, malaria, zika, chikungunya, or filariosis, causing millions of deaths worldwide. French Polynesia is taking a groundbreaking initiative to address public health concerns and demonstrate a commitment to finding environmentally friendly solutions to curb disease spread. Building on a successful decade-long pilot project on the atoll Teti’aroa, the innovative method involves the strategic release of sterilised male Aedes Aegypti mosquitoes. The process sees the release of sterile males that will "contaminate" females, rendering them sterile and thereby naturally reducing the proliferation of the disease-bearing insect population. The Louis Malardé Institute's entomology laboratory says they have now developed an X-ray device that can mass-sterilise the males.
Antiviral Wolbachia strains associate with Aedes aegypti endoplasmic reticulum membranes and induce lipid droplet formation to restrict dengue virus replication
28757Robson K. Loterio, Ebony A. Monson, Rachel Templin, Jyotika T. de Bruyne, Heather A. Flores, Jason M. Mackenzie, Georg Ramm, Karla J. Helbig, Cameron P. Simmons, Johanna E. Fraser, Applied and Environmental Microbiology, 2023-12-22 16:16:14.
Wolbachia are a genus of insect endosymbiotic bacteria which includes strains wMel and wAlbB that are being utilized as a biocontrol tool to reduce the incidence of Aedes aegypti-transmitted viral diseases like dengue. However, the precise mechanisms underpinning the antiviral activity of these Wolbachia strains are not well defined. Here, we generated a panel of Ae. aegypti-derived cell lines infected with antiviral strains wMel and wAlbB or the non-antiviral Wolbachia strain wPip to understand host cell morphological changes specifically induced by antiviral strains. Antiviral strains were frequently found to be entirely wrapped by the host endoplasmic reticulum (ER) membrane, while wPip bacteria clustered separately in the host cell cytoplasm. ER-derived lipid droplets (LDs) increased in volume in wMel- and wAlbB-infected cell lines and mosquito tissues compared to cells infected with wPip or Wolbachia-free controls. Inhibition of fatty acid synthase (required for triacylglycerol biosynthesis) reduced LD formation and significantly restored ER-associated dengue virus replication in cells occupied by wMel. Together, this suggests that antiviral Wolbachia strains may specifically alter the lipid composition of the ER to preclude the establishment of dengue virus (DENV) replication complexes. Defining Wolbachia’s antiviral mechanisms will support the application and longevity of this effective biocontrol tool that is already being used at scale.
Rapid turnover of pathogen-blocking Wolbachia and their incompatibility loci
28733Shropshire JD, Conner WR, Vanderpool D, Hoffmann AA, Turelli M, Cooper BS., bioRxiv, 2023-12-19 16:02:29.
At least half of all insect species carry maternally inherited Wolbachia alphaproteobacteria, making Wolbachia the most common endosymbionts in nature. Wolbachia spread to high frequencies is often due to cytoplasmic incompatibility (CI), a Wolbachia -induced sperm modification that kills embryos without Wolbachia . Several CI-causing Wolbachia variants, including w Mel from Drosophila melanogaster , also block viruses. Establishing pathogen-blocking w Mel in natural Aedes aegypti mosquito populations has reduced dengue disease incidence, with one study reporting about 85% reduction when w Mel frequency is high. However, w Mel transinfection establishment is challenging in many environments, highlighting the importance of identifying CI-causing Wolbachia variants that stably persist in diverse hosts and habitats. We demonstrate that w Mel-like variants have naturally established in widely distributed holometabolous dipteran and hymenopteran insects that diverged approximately 350 million years ago, with w Mel variants spreading rapidly among these hosts over only the last 100,000 years. Wolbachia genomes contain prophages that encode CI-causing operons ( cifs ). These cifs move among Wolbachia genomes - with and without prophages - even more rapidly than Wolbachia move among insect hosts. Our results shed light on how rapid host switching and horizontal gene transfer contribute to Wolbachia and cif diversity in nature. The diverse w Mel variants we report here from hosts present in different climates offer many new options for broadening Wolbachia -based biocontrol of diseases and pests.
Procesos celulares modificados en Aedes aegypti infectados con Wolbachia y la susceptibilidad al virus dengue
28696López-Ordóñez T, Díaz-Rodarte KI, Torres-Monzón JA, Casas-Martínez M, Danis-Lozano R, Mosso-González C., Salud Pública de México, 2023-12-12 14:35:34.
Objetivo: Analizar la expresión diferencial de proteínas de Aedes aegypti infectados con Wolbachia y su asociación con el ciclo viral del virus dengue (DENV). Material y métodos. Se revisó una base de datos de proteínas de Ae. aegypti infec-tados y no infectados con Wolbachia, cepa wMel y se buscaron estas en revistas indizadas, que hablaran de la proteína y el ciclo viral de DENV. Resultados: La expresión diferencial de proteínas de los mosquitos durante la infección con Wolbachia intervienen en los procesos de entrada, replicación y salida del DENV. Conclusiones: Existen cambios en la expresión de proteínas de células infectadas con Wolbachia, que son necesarias para el ciclo de replicación de DENV, explicando porque algunos mosquitos infectados con Wolbachia son refractarios a la infección por DENV.
Aerial release of Aedes aegypti male mosquitoes using an unmanned aerial vehicle: a novel control strategy
28690Valdez-Delgado KM, Ríos-Delgado JC, Nettel-Cruz JA, Angulo-Kladt R, Villarreal-Treviño C., Salud Pública de México, 65. 2023-12-12 14:17:22.
Objective. To development of a methodology for the chilling, handling, transport, and release of male Aedes aegypti mosquitoes, reared in insectary conditions to release in the field with unmanned vehicles to compete sexually with wild males in the field. Materials and methods. A population of Ae. aegypti from different areas in Tapachula, Chiapas, was used. Laboratory tests were conducted: Effect of temperature and cooling time on the knockdown, recovery of males, and copulatory success. Results. The chilling temperature of 3 ± 1ºC for 30 min, was used as a knockdown temperature before handling, packing, transportation, and aerial release. The males subjected to the entire process, including the semi-field aerial release test, showed normal sexual behavior activity, obtaining 100% of females inseminated. Conclusion. These results present the feasibility of applying a new control methodology using unmanned aerial vehicle (UAV) as support for the sterile insect release technique (SIT), use of Wolbachia or both, in male Ae. aegypti, for the design of strategies to control their populations.
Reduced dengue incidence following city-wide wMel Wolbachia mosquito releases throughout three Colombian cities: Interrupted time series analysis and a prospective case-control study
28647Velez ID, Tanamas SK, Arbelaez MP, Kutcher SC, Duque SL, Uribe A, et al., PLoS Neglected Tropical Diseases, 2023-12-05 10:26:43.
The introduction of Wolbachia (wMel strain) into Aedes aegypti mosquitoes reduces their capacity to transmit dengue and other arboviruses. Randomised and non-randomised studies in multiple countries have shown significant reductions in dengue incidence following field releases of wMel-infected Ae. aegypti. Stable introduction of wMel into local Ae. aegypti populations was associated with a significant and sustained reduction in dengue incidence across three Colombian cities. These results from the largest contiguous Wolbachia releases to-date demonstrate the real-world effectiveness of the method across large urban populations and, alongside previously published results, support the reproducibility of this effectiveness across different ecological settings.
Large-scale releases and establishment of wMel Wolbachia in Aedes aegypti mosquitoes throughout the Cities of Bello, Medellín and Itagüí, Colombia
28645Velez ID, Uribe A, Barajas J, Uribe S, Ángel S, Suaza-Vasco JD, et al., PLoS Neglected Tropical Diseases, 2023-12-05 10:11:27.
The wMel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and has been shown to reduce the transmission of dengue and other Aedes-borne viruses. Here we report the entomological results from phased, large-scale releases of Wolbachia infected Ae. aegypti mosquitoes throughout three contiguous cities located in the Aburrá Valley, Colombia. These results, from the largest contiguous releases of wMel Wolbachia mosquitoes to date, highlight the operational feasibility of implementing the method in large urban settings. Based on results from previous studies, we expect that Wolbachia establishment will be sustained long term. Ongoing monitoring will confirm Wolbachia persistence in local mosquito populations and track its establishment in the remaining areas.
Wolbachia Transinfection Via Embryonic Microinjection
28593Zhang, M., Xi, Z., Methods in Molecular Biology, 2739. 2023-11-29 16:22:25.
The process of transferring Wolbachia from one species to another to establish a stable, maternally inherited infection in the target species is known as transinfection. The success of transinfection is primarily achieved through embryonic microinjection, which is the most direct and efficient means of delivering Wolbachia into the germline of the target species and establishing stable maternal transmission. For the fundamental studies, transinfection is often used to characterize Wolbachia-host interactions, including Wolbachia host range, the role of host or bacterial factors in symbiosis, and evolution of Wolbachia-host associations. For the applied studies, use of transinfection to generate a novel infection in the target species is the first step to build the weapon for both population replacement and population suppression for controlling insect pests or their transmitted diseases. For the primary dengue vector Aedes aegypti and Anopheles vectors of malaria, which either do not naturally carry Wolbachia or are infected with strains that lack necessary features for implementation, transinfection can be established by introducing a novel strain capable of inducing both cytoplasmic incompatibility (CI) and pathogen blocking. For A. albopictus and Culex mosquito species, which naturally harbor CI-inducing Wolbachia, transinfection can be achieved by either introducing a novel strain to generate superinfection or replacing the native infection with a different Wolbachia strain in a symbiont-free line, which is derived from antibiotic treatment of the wild type. Here, we use A. aegypti as an example to describe the Wolbachia transinfection method, which can be adapted to other insect species, such as planthoppers, according to their specific developmental requirements.
Different mechanisms of X-ray irradiation-induced male and female sterility in Aedes aegypti
28570Zhang, H., Trueman, E., Hou, X. et al., BMC Biology, 21. 2023-11-29 14:14:21.
Aedes aegypti (Ae. aegypti) is the major vector that transmits many diseases including dengue, Zika, and filariasis in tropical and subtropical regions. Due to the growing resistance to chemical-based insecticides, biological control methods have become an emerging direction to control mosquito populations. The sterile insect technique (SIT) deploys high doses of ionizing radiation to sterilize male mosquitoes before the release. The Wolbachia-based population suppression method of the incompatible insect technique (IIT) involves the release of Wolbachia-infected males to sterilize uninfected field females. Due to the lack of perfect sex separation tools, a low percentage of female contamination is detected in the male population. To prevent the unintentional release of these Wolbachia-infected females which might result in population replacement, a low dose of X-ray irradiation is deployed to sterilize any female escapees. However, it remains unclear whether these irradiation-induced male and female sterilizations share common mechanisms.
Efficient sex separation by exploiting differential alternative splicing of a dominant marker in Aedes aegypti
28568Shih-Che Weng, Igor Antoshechkin, Eric Marois, Omar S. Akbari, PLoS Genetics, 2023-11-29 14:02:53.
Only female mosquitoes consume blood giving them the opportunity to transmit deadly human pathogens. Therefore, it is critical to remove females before conducting releases for genetic biocontrol interventions. Here we describe a robust sex-sorting approach termed SEPARATOR (Sexing Element Produced by Alternative RNA-splicing of A Transgenic Observable Reporter) that exploits sex-specific alternative splicing of an innocuous reporter to ensure exclusive dominant male-specific expression. Using SEPARATOR, we demonstrate reliable sex selection from early larval and pupal stages in Aedes aegypti, and use a Complex Object Parametric Analyzer and Sorter (COPAS) to demonstrate scalable high-throughput sex-selection of first instar larvae. Additionally, we use this approach to sequence the transcriptomes of early larval males and females and find several genes that are sex-specifically expressed. SEPARATOR can simplify mass production of males for release programs and is designed to be cross-species portable and should be instrumental for genetic biocontrol interventions.
Utility of surveillance data for planning for dengue elimination in Yogyakarta, Indonesia: a scenario-tree modelling approach
28536Melanie Bannister-Tyrrell, Alison Hillman, Citra Indrian, Riris Andono Ahmad, Adi Utarini, Cameron P Simmons, Katherine L Anders, Evan Sergeant, BMJ Global Health, 8. 2023-11-28 10:54:45.
Field trials and modelling studies suggest that elimination of dengue transmission may be possible through widespread release of Aedes aegypti mosquitoes infected with the insect bacterium Wolbachia pipientis (wMel strain), in conjunction with routine dengue control activities. This study aimed to develop a modelling framework to guide planning for the potential elimination of locally acquired dengue in Yogyakarta, a city of almost 400 000 people in Java, Indonesia. A scenario-tree modelling approach was used to estimate the sensitivity of the dengue surveillance system (including routine hospital-based reporting and primary-care-based enhanced surveillance), and time required to demonstrate elimination of locally acquired dengue in Yogyakarta city, assuming the detected incidence of dengue decreases to zero in the future. Age and gender were included as risk factors for dengue, and detection nodes included the probability of seeking care, probability of sample collection and testing, diagnostic test sensitivity and probability of case notification. Parameter distributions were derived from health system data or estimated by expert opinion. Alternative simulations were defined based on changes to key parameter values, separately and in combination. For the default simulation, median surveillance system sensitivity was 0.131 (95% PI 0.111 to 0.152) per month. Median confidence in dengue elimination reached 80% after a minimum of 13 months of zero detected dengue cases and 90% confidence after 25 months, across different scenarios. The alternative simulations investigated produced relatively small changes in median system sensitivity and time to elimination. This study suggests that with a combination of hospital-based surveillance and enhanced clinic-based surveillance for dengue, an acceptable level of confidence (80% probability) in the elimination of locally acquired dengue can be reached within 2 years. Increasing the surveillance system sensitivity could shorten the time to first ascertainment of elimination of dengue and increase the level of confidence in elimination.
Symbiotic Wolbachia in mosquitoes and its role in reducing the transmission of mosquito-borne diseases: updates and prospects
28311A. Minwuyelet, G. P. Petronio, D. Yewhalaw, A. Sciarretta, I. Magnifico, D. Nicolosi, R. Di Marco and G. Atenafu, Frontiers in Microbiology, 14. 2023-11-08 08:20:47.
Mosquito-borne diseases such as malaria, dengue fever, West Nile virus, chikungunya, Zika fever, and filariasis have the greatest health and economic impact. These mosquito-borne diseases are a major cause of morbidity and mortality in tropical and sub-tropical areas. Due to the lack of effective vector containment strategies, the prevalence and severity of these diseases are increasing in endemic regions. Nowadays, mosquito infection by the endosymbiotic Wolbachia represents a promising new bio-control strategy. Wild-infected mosquitoes had been developing cytoplasmic incompatibility (CI), phenotypic alterations, and nutrition competition with pathogens. These reduce adult vector lifespan, interfere with reproduction, inhibit other pathogen growth in the vector, and increase insecticide susceptibility of the vector. Wild, uninfected mosquitoes can also establish stable infections through trans-infection and have the advantage of adaptability through pathogen defense, thereby selectively infecting uninfected mosquitoes and spreading to the entire population. This review aimed to evaluate the role of the Wolbachia symbiont with the mosquitoes (Aedes, Anopheles, and Culex) in reducing mosquito-borne diseases. Global databases such as PubMed, Web of Sciences, Scopus, and pro-Quest were accessed to search for potentially relevant articles. We used keywords: Wolbachia, Anopheles, Aedes, Culex, and mosquito were used alone or in combination during the literature search. Data were extracted from 56 articles’ texts, figures, and tables of the included article.
Success of Wolbachia-infected mosquitoes in fighting dengue may be underestimated
28353B. Wampler, Notre Dame News, 2023-11-06 11:04:57.
Now, researchers at the University of Notre Dame have conducted an analysis of the World Mosquito Program’s randomized control trial of Wolbachia-infected mosquitoes in Indonesia, looking at how excluding transmission dynamics impacted the original interpretation of the trial’s results. “Randomized controlled trials are the gold standard for evaluating the efficacy of any medical or public health intervention. That is very difficult for vector interventions against dengue because incidence of the disease can be somewhat unpredictable and sporadic, requiring very large-scale trials,” said Alex Perkins, associate professor of biological sciences at Notre Dame and senior author on the study. The study published in BMJ Global Health used mathematical models to analyze dengue virus transmission during the Indonesia trial. They explored three biases, or sources of potential error, that the trial is subject to: human movement, mosquito movement and the combined transmission dynamics between human and mosquito movement.
The double-edged sword effect of expanding Wolbachia deployment in dengue endemic settings
28137M. G. Pavan, G. A. Garcia, M. R. David and R. Maciel-de-Freitas, The Lancet Regional Health - Americas, 27:100610. 2023-10-02 10:16:37.
We can use Brazil as a showcase to foresee and avoid a double-edged sword effect associated with Wolbachia releases. Insecticide resistance of native Ae. aegypti populations is spread worldwide (http://aedes.irmapper.com), and positive results should boost Wolbachia deployment in other dengue endemic settings around the world. Aedes aegypti populations are heterogeneous and nationwide releases of a Wolbachia strain whose genetic backcross belong to a specific locality would produce an unsought homogenization of vector populations. Aedes aegypti homogenisation at large geographic scales could impose additional undesirable consequences in the long-term by promoting genetic hitchhiking of traits such as higher vector competence, lower susceptibility to repellents and insecticides, or more avid host-seeking and biting behaviour. Available data has shown that ensuring adherence to local characteristics, specially a matching genetic between native and released mosquitoes, is critical to enhance the likelihood of achieving a faster introgression in the field, realizing cost and time savings over the globe. Probably there are a myriad of yet undiscovered traits beyond insecticide resistance that may influence vector local adaptation and would affect the success of released strains. Therefore, neglecting the genetic diversity in favour of centralising the rearing of mosquitoes with Wolbachia for nationwide releases could represent a drawback for future releases. Long-term studies regarding the consequences of releasing mosquitoes with homogenous genotypes in diverse ecological and epidemiological scenarios remain a critical research priority, essential for informed decision-making and sustainable management of mosquito-borne diseases.
Unleashing a New Weapon on the Mosquito: A Mosquito
27987S. Nolen and E. Lutz, New York Times, 2023-09-29 08:05:43.
Five decades ago, entomologists confronting the many kinds of suffering that mosquitoes inflict on humans began to consider a new idea: What if, instead of killing the mosquitoes (a losing proposition in most places), you could disarm them? Even if you couldn’t keep them from biting people, what if you could block them from passing on disease? What if, in fact, you could use one infectious microbe to stop another? These scientists began to consider a parasitic bacteria called Wolbachia, which lives quietly in all kinds of insect species. A female mosquito with Wolbachia passes it on in her eggs to all of her offspring, who eventually pass it on to the next generation. But Wolbachia isn’t naturally found in the mosquito species that cause humans the most problems — the Aedes aegypti, the virus carrier, and the Anopheles subspecies, which carry malaria. If it were, it might eventually render those species essentially harmless. So how do you infect a mosquito with Wolbachia?
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.
Mimicking superinfection exclusion disrupts alphavirus infection and transmission in the yellow fever mosquito Aedes aegypti
27839Reitmayer, Christine M. Levitt, Emily Basu, Sanjay Atkinson, Barry Fragkoudis, Rennos Merits, Andres Lumley, Sarah Larner, Will Diaz, Adriana V. Rooney, Sara Thomas, Callum J. E. von Wyschetzki, Katharina Rausalu, Kai Alphey, Luk, Proceedings of the National Academy of Sciences, 120:e2303080120. 2023-09-12 09:18:45.
Multiple viruses, including pathogenic viruses, bacteriophages, and even plant viruses, cause a phenomenon termed superinfection exclusion whereby a currently infected cell is resistant to secondary infection by the same or a closely related virus. In alphaviruses, this process is thought to be mediated, at least in part, by the viral protease (nsP2) which is responsible for processing the nonstructural polyproteins (P123 and P1234) into individual proteins (nsP1?nsP4), forming the viral replication complex. Taking a synthetic biology approach, we mimicked this naturally occurring phenomenon by generating a superinfection exclusion-like state in Aedes aegypti mosquitoes, rendering them refractory to alphavirus infection. By artificially expressing Sindbis virus (SINV) and chikungunya virus (CHIKV) nsP2 in mosquito cells and transgenic mosquitoes, we demonstrated a reduction in both SINV and CHIKV viral replication rates in cells following viral infection as well as reduced infection prevalence, viral titers, and transmission potential in mosquitoes.
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.
Molecular Evidence of Wolbachia Species in Wild-Caught Aedes albopictus and Aedes aegypti Mosquitoes in Four States of Northeast India
27843Vinayagam, S. Nirmolia, T. Chetry, S. Kumar, N. P. Saini, P. Bhattacharyya, D. R. Bhowmick, I. P. Sattu, K. Patgiri, S. J., Journal of Tropical Medicine, 2023-09-05 09:37:52.
Wolbachia, a Gram-negative intracellular bacterium, naturally infects many arthropods, including mosquito vectors responsible for the spread of arboviral diseases such as Zika, chikungunya, and dengue fever. Certain Wolbachia strains are involved in inhibiting arbovirus replication in mosquitoes, and this phenomenon is currently being studied to combat disease vectors. A study was conducted in four states in north-eastern India to investigate the presence of natural Wolbachia infection in wild-caught Aedes albopictus and Aedes aegypti mosquitoes, the established vectors of dengue. The detection of a Wolbachia infection was confirmed by nested PCR and sequencing in the two mosquito species Ae. aegypti and Ae. albopictus. Positivity rates observed in Ae. aegypti and Ae. albopictus pools were 38% (44 of 115) and 85% (41 of 48), respectively, and the difference was significant (chi-square = 28.3174, p = 0.00000010). Sequencing revealed that all detected Wolbachia strains belonged to supergroup B. Although Wolbachia infection in Ae. aegypti has been previously reported from India, no such reports are available from north-eastern India. Data on naturally occurring Wolbachia strains are essential for selecting the optimal strain for the development of Wolbachia-based control measures. This information will be helpful for the future application of Wolbachia-based vector control measures in this part of the country.
Jamestown Canyon virus is transmissible by Aedes aegypti and is only moderately blocked by Wolbachia co-infection
27755M. J. Lau, H. L. C. Dutra, M. J. Jones, B. P. McNulty, A. M. Diaz, F. Ware-Gilmore and E. A. McGraw, PLOS Neglected Tropical Diseases, 17. 2023-09-05 07:50:16.
Jamestown Canyon virus (JCV), a negative-sense arbovirus, is increasingly common in the upper Midwest of the USA. Transmitted by a range of mosquito genera, JCV's primary amplifying host is white-tailed deer. Aedes aegypti is responsible for transmitting various positive-sense viruses globally including dengue (DENV), Zika, chikungunya, and Yellow Fever. Ae. aegypti's distribution, once confined to the tropics, is expanding, in part due to climate change. Wolbachia, an insect endosymbiont, limits the replication of co-infecting viruses inside insects. The release and spread of the symbiont into Ae. aegypti populations have been effective in reducing transmission of DENV to humans, although the mechanism of Wolbachia-mediated viral blocking is still poorly understood. Here we explored JCV infection potential in Ae. aegypti, the nature of the vector's immune response, and interactions with Wolbachia infection. We show that Ae. aegypti is highly competent for JCV, which grows to high loads and rapidly reaches the saliva after an infectious blood meal. The mosquito immune system responds with strong induction of RNAi and JAK/STAT. Neither the direct effect of viral infection nor the energetic investment in immunity appears to affect mosquito longevity. Wolbachia infection blocked JCV only in the early stages of infection. Wolbachia-induced immunity was small compared to that of JCV, suggesting innate immune priming does not likely explain blocking. We propose two models to explain why Wolbachia's blocking of negative-sense viruses like JCV may be less than that of positive-sense viruses, relating to the slowdown of host protein synthesis and the triggering of interferon-like factors like Vago. In conclusion, we highlight the risk for increased human disease with the predicted future overlap of Ae. aegypti and JCV ranges. We suggest that with moderate Wolbachia-mediated blocking and distinct biology, negative-sense viruses represent a fruitful comparator model to other viruses for understanding blocking mechanisms in mosquitoes.
A synthetic biology approach to transgene expression
27699P. Leftwich, T. , J. Purcell, C. , M. Anderson, A. E. , R. Fragkoudis, S. Basu, G. Lycett, T. and L. Alphey, bioRxiv, 2023.08.31.555539. 2023-08-31 09:13:32.
The ability to control gene expression is pivotal in genetic engineering and synthetic biology. However, in most non-model and pest insect species, empirical evidence for predictable modulation of gene expression levels is lacking. This knowledge gap is critical for genetic control systems, particularly in mosquitoes, where transgenic methods offer novel routes for pest control. Commonly, the choice of RNA polymerase II promoter (Pol II) is the primary method for controlling gene expression, but the options are limited. To address this, we developed a systematic approach to characterize modifications in translation initiation sequences (TIS) and 3' untranslated regions (UTR) of transgenes, enabling the creation of a toolbox for gene expression modulation in mosquitoes and potentially other insects. The approach demonstrated highly predictable gene expression changes across various cell lines and promoter sequences, representing a significant advancement in mosquito synthetic biology gene expression.Competing Interest StatementThe authors have declared no competing interest.
Wolbachia wMel strain-mediated effects on dengue virus vertical transmission from Aedes aegypti to their offspring
27693K. Duong Thi Hue, D. da Silva Goncalves, V. Tran Thuy, L. Thi Vo, D. Le Thi, N. Vu Tuyet, G. Nguyen Thi, T. Huynh Thi Xuan, N. Nguyen Minh, P. Nguyen Thanh, S. Yacoub and C. P. Simmons, Parasites and Vectors, 16:308. 2023-08-31 08:53:50.
Background Dengue virus serotypes (DENV-1 to -4) can be transmitted vertically in Aedes aegpti mosquitoes. Whether infection with the wMel strain of the endosymbiont Wolbachia can reduce the incidence of vertical transmission of DENV from infected females to their offspring is not well understood. Methods A laboratory colony of Vietnamese Ae. aegypti, both with and without wMel infection, were infected with DENV-1 by intrathoracic injection (IT) to estimate the rate of vertical transmission (VT) of the virus. VT in the DENV-infected mosquitoes was calculated via the infection rate estimation from mosquito pool data using maximum likelihood estimation (MLE). Results In 6047 F1 Vietnamese wild-type Ae. aegypti, the MLE of DENV-1 infection was 1.49 per 1000 mosquitoes (95% confidence interval [CI] 0.73–2.74). In 5500 wMel-infected Ae. aegypti, the MLE infection rate was 0 (95% CI 0–0.69). The VT rates between mosquito lines showed a statistically significant difference. Conclusions The results reinforce the view that VT is a rare event in wild-type mosquitoes and that infection with wMel is effective in reducing VT.
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.
wMel Wolbachia alters female post-mating behaviors and physiology in the dengue vector mosquito Aedes aegypti
27649J. Osorio, S. Villa-Arias, C. Camargo, L. F. Ramírez-Sánchez, L. M. Barrientos, C. Bedoya, G. Rúa-Uribe, S. Dorus, C. Alfonso-Parra and F. W. Avila, Communications Biology, 6:865. 2023-08-21 06:53:59.
Globally invasive Aedes aegypti disseminate numerous arboviruses that impact human health. One promising method to control Ae. aegypti populations is transinfection with Wolbachia pipientis, which naturally infects ~40–52% of insects but not Ae. aegypti. Transinfection of Ae. aegypti with the wMel Wolbachia strain induces cytoplasmic incompatibility (CI), allows infected individuals to invade native populations, and inhibits transmission of medically relevant arboviruses by females. Female insects undergo post-mating physiological and behavioral changes—referred to as the female post-mating response (PMR)—required for optimal fertility. PMRs are typically elicited by male seminal fluid proteins (SFPs) transferred with sperm during mating but can be modified by other factors, including microbiome composition. Wolbachia has modest effects on Ae. aegypti fertility, but its influence on other PMRs is unknown. Here, we show that Wolbachia influences female fecundity, fertility, and re-mating incidence and significantly extends the longevity of virgin females. Using proteomic methods to examine the seminal proteome of infected males, we found that Wolbachia moderately affects SFP composition. However, we identified 125 paternally transferred Wolbachia proteins, but the CI factor proteins (Cifs) were not among them. Our findings indicate that Wolbachia infection of Ae. aegypti alters female PMRs, potentially influencing control programs that utilize Wolbachia-infected individuals.
British super mosquitoes being deployed to wipe out malaria from the planet
27622J. Lawton, Daily Star, 2023-08-15 10:00:16.
The Brit-made mosquitoes are all male and carry a special gene to prevent female offspring from surviving into adulthood.Only females bite and spread malaria. Released into the wild Oxitec’s genetically-modified males mate with wild females. All the female offspring then die. Males - which do not bite or spread the disease - survive and go on to mate with other wild females `dramatically’ reducing the world’s mosquito population and the "spread of malaria". according to Gates. Tests have shown the super mozzies pose no risk to the environment or humans. More than one billion have so far been released worldwide with "no negative impacts", Bill wrote in an online blog. In Brazil the Brit buzzers are helping eliminate dengue fever - another mosquito-transmitted disease which kills up to 40,000-a-year. They will be introduced to Djibouti in east Africa next year to stop a rise in the number of malaria cases from 27 in 2012 to 73,000 in 2020.
EPA Authorized Release Of 2 Billion More GMO Mosquitos
27606T. Mateescu, Health Thoroughfare, 2023-08-09 07:34:11.
A biotechnology company called Oxitec has produced genetically modified mosquitoes named GE mosquitoes. These mosquitoes are being released in the U.S. for a real-world experiment. Oxitec is using Aedes aegypti (A. aegypti) mosquitoes for this experiment. This species is known to carry diseases like yellow fever, dengue fever, chikungunya, Zika, West Nile, and Mayaro, a dengue-like disease. Oxitec genetically engineered the males of this species to carry a “genetic kill switch.” When they mate with wild female mosquitoes, their offspring inherit the lethal gene, and they cannot survive or reproduce in the wild. Oxitec is marketing these insects as “Oxitec Friendly” mosquitoes in the U.S.
Modeling shows emerging mosquito control approach might be largely resistant to warming temperatures
27595B. Yirka, Phys Org, 2023-08-07 06:48:13.
A team of epidemiologists and engineers at the University of California, working with a colleague from QIMR Berghofer Medical Research Institute, in Australia, has found via modeling that the use of the Wolbachia approach to slowing the spread of mosquito-borne diseases (MBDs) is likely to survive climate change—at least in the near term. In their study, reported in the journal Nature Climate Change, the group used population dynamic models using data on mosquitos and Wolbachia bacteria along with temperature increases due to climate change. Eric Caragata, with the University of Florida, has published a News & Views piece in the same journal issue, outlining the work done by the team on this new effort.
Scientists are releasing disease-resistant mosquitoes. But heat waves could kill them.
27586C. Harvey, Politico, 2023-08-04 08:21:30.
A new study, published Thursday in the journal Nature Climate Change, suggests that the disease-quashing bugs will likely survive for at least the next couple of decades. Their fate is less certain further into the future. The study focuses on a special insect-borne bacterium called Wolbachia, which has natural virus-blocking properties and is carried in different insect populations, including some mosquito species. It’s not typically found in Aedes aegypti, or the “yellow fever mosquito,” one of the most significant disease-carrying species on the planet. But scientists have figured out ways to introduce the bacteria into Aedes aegypti populations — and potentially slow the transmission of diseases including yellow fever and dengue fever and the Zika and chikungunya viruses.
Suppression Trial through an Integrated Vector Management of Aedes albopictus (Skuse) Based on the Sterile Insect Technique in a Non-Isolated Area in Spain
27563C. Tur, D. Almenar, M. Zacarés, S. Benlloch-Navarro, I. Pla and V. Dalmau, Insects, 14. 2023-08-03 07:16:56.
In recent years, Aedes albopictus (Skuse, 1984) has expanded its distribution globally due to its high ecological plasticity. This expansion has increased the population’s susceptibility to contracting diseases such as dengue, Zika, and chikungunya, among others, which are transmitted by this mosquito species. In the absence of effective control methods, the application of the sterile insect technique (SIT) is proposed as part of an integrated vector management (IVM) program. From 2007 to 2020, this strategy has been tested in a non-isolated mosquito population urban area of 45 ha, representative of the municipalities of the Valencian region (Spain). The population levels of adult females and eggs collected in the traps have been reduced by 70–80% compared to the control area, demonstrating its efficacy in reducing mosquito populations. This work analyzes the impact of the migration of the wild mosquito population from the peri-urban area to the urban core.
wMel replacement of dengue-competent mosquitoes is robust to near-term change
27584V. N. Vásquez, L. M. Kueppers, G. Rašić and J. M. Marshall, Nature Climate Change, 13:848-855. 2023-08-01 08:16:33.
Rising temperatures are impacting the range and prevalence of mosquito-borne diseases. A promising biocontrol technology replaces wild mosquitoes with those carrying the virus-blocking Wolbachia bacterium. Because the most widely used strain, wMel, is adversely affected by heat stress, we examined how global warming may influence wMel-based replacement. We simulated interventions in two locations with successful field trials using Coupled Model Intercomparison Project Phase 5 climate projections and historical temperature records, integrating empirical data on wMel’s thermal sensitivity into a model of Aedes aegypti population dynamics to evaluate introgression and persistence over one year. We show that in Cairns, Australia, climatic futures necessitate operational adaptations for heatwaves exceeding two weeks. In Nha Trang, Vietnam, projected heatwaves of three weeks and longer eliminate wMel under the most stringent assumptions of that symbiont’s thermal limits. We conclude that this technology is generally robust to near-term (2030s) climate change. Accelerated warming may challenge this in the 2050s and beyond.
Susceptibility of Wolbachia mosquito control to temperature shifts
27579E. P. Caragata, Nature Climate Change, 13:767-768. 2023-08-01 08:10:19.
Vásquez and colleagues consider the potential impacts of increasing and variable temperatures on Wolbachia-based population-replacement interventions. Previous laboratory experiments have highlighted the temperature-sensitive nature of Wolbachia, with high average daily temperatures and prolonged heatwaves potentially decreasing Wolbachia titre, leading to weakening or loss of maternal transmission, cytoplasmic incompatibility and virus blocking . In nature, this could potentially hinder or thwart interventions. Vásquez and colleagues use Coupled Model Intercomparison Project Phase 5 climate projections to model the efficacy of population-replacement interventions utilizing the wMel Wolbachia strain in Ae. aegypti in Cairns, Australia, and in Nha Trang, Vietnam, two current intervention sites. Their mechanistic models compare population-replacement efficiency under current temperature regimes, and those projected for the 2030s (2024–2039) and 2050s (2044–2059). These models also incorporate loss of wMel infection at an average daily temperature threshold of 35 °C (based on laboratory data ), or more stringently, at 33 °C or 31.5 °C.
New Study Improves Sterile Insect Technique for Mosquitoes
26600E. Ricciuti, Entomology Today, 2023-07-12 12:59:23.
As Florida health authorities work to respond to an ever-growing cadre of invasive tropical mosquitoes, a research team has sharpened an environmentally friendly tool increasingly deployed against a dangerous species that invaded the state two centuries ago. The mosquito is Aedes aegypti, vector of yellow fever, dengue fever, chikungunya, and Zika fever. It is one of the mosquitoes increasingly targeted with the sterile insect technique (SIT), in which male insects reared en masse are sterilized by gamma-ray or x-ray ionization and released to mate with wild females, which then produce non-viable eggs. Besides being environmentally innocuous, SIT is not hindered by insecticide resistance, a huge plus for pest managers. Long used against flies and other agricultural insect pests, SIT has shown promise against disease vectors such as mosquitoes, but a few wrinkles have kept it from reaching full potential. Research on Aedes aegypti described in a new study published in June in the Journal of Medical Entomology has smoothed the process, showing that the success of SIT can be measurably enhanced if male mosquitoes are sterilized when they emerge as adults, rather than as pupae, the approach now in use.
Estimating mosquito abundance and population suppression in an incompatible insect technique study
26901L. Griffin, D. Pagendam, C. Drovandi, B. Trewin and N. W. Beebe, Journal of Applied Ecology, 2023-07-10 10:53:08.
Our model can provide valuable insights that can shape decision support systems in sterile insect technique and incompatible insect technique programmes operating over large geographical scales. The model helps determine how many sterile/incompatible insects should be released over time and how population control is progressing (via use of counterfactual scenarios). These outcomes are achieved because the model provides estimates of wild-type populations over time, even when there has been no differentiation between sterile/incompatible and wild-type insects caught in trap
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.
Wolbachia -mediated resistance to Zika virus infection in Aedes aegypti is dominated by diverse transcriptional regulation and weak evolutionary pressures
26604E. C. Boehm, A. S. Jaeger, H. J. Ries, D. Castañeda, A. M. Weiler, C. C. Valencia, J. Weger-Lucarelli, G. D. Ebel, S. L. O'Connor, T. C. Friedrich, M. Zamanian and M. T. Aliota, bioRxiv, 2023-06-26 13:09:35.
A promising candidate for arbovirus control and prevention relies on replacing arbovirus-susceptible Aedes aegypti populations with mosquitoes that have been colonized by the intracellular bacterium Wolbachia and thus have a reduced capacity to transmit arboviruses. This reduced capacity to transmit arboviruses is mediated through a phenomenon referred to as pathogen blocking. Pathogen blocking has primarily been proposed as a tool to control dengue virus (DENV) transmission, however it works against a range of viruses, including Zika virus (ZIKV). Despite years of research, the molecular mechanisms underlying pathogen blocking still need to be better understood. Here, we used RNA-seq to characterize mosquito gene transcription dynamics in Ae. aegypti infected with the w Mel strain of Wolbachia that are being released by the World Mosquito Program in Medellín, Colombia. Comparative analyses using ZIKV-infected, uninfected tissues, and mosquitoes without Wolbachia revealed that the influence of w Mel on mosquito gene transcription is multifactorial. Importantly, because Wolbachia limits, but does not completely prevent, replication of ZIKV and other viruses in coinfected mosquitoes, there is a possibility that these viruses could evolve resistance to pathogen blocking. Therefore, to understand the influence of Wolbachia on within-host ZIKV evolution, we characterized the genetic diversity of molecularly barcoded ZIKV virus populations replicating in Wolbachia -infected mosquitoes and found that within-host ZIKV evolution was subject to weak purifying selection and, unexpectedly, loose anatomical bottlenecks in the presence and absence of Wolbachia . Together, these findings suggest that there is no clear transcriptional profile associated with Wolbachia -mediated ZIKV restriction, and that there is no evidence for ZIKV escape from this restriction in our system. AUTHOR SUMMARY: When Wolbachia bacteria infect Aedes aegypti mosquitoes, they dramatically reduce the mosquitoes' susceptibility to infection with a range of arthropod-borne viruses, including Zika virus (ZIKV). Although this pathogen-blocking effect has been widely recognized, its mechanisms remain unclear. Furthermore, because Wolbachia limits, but does not completely prevent, replication of ZIKV and other viruses in coinfected mosquitoes, there is a possibility that these viruses could evolve resistance to Wolbachia -mediated blocking. Here, we use host transcriptomics and viral genome sequencing to examine the mechanisms of ZIKV pathogen blocking by Wolbachia and viral evolutionary dynamics in Ae. aegypti mosquitoes. We find complex transcriptome patterns that do not suggest a single clear mechanism for pathogen blocking. We also find no evidence that Wolbachia exerts detectable selective pressures on ZIKV in coinfected mosquitoes. Together our data suggest that it may be difficult for ZIKV to evolve Wolbachia resistance, perhaps due to the complexity of the pathogen blockade mechanism.
Developing methods for chilling, compacting, and sterilizing adult Aedes aegypti (Diptera: Culicidae) and comparing mating competitiveness between males sterilized as adults versus pupae for sterile male release
26602D. A. Tussey, R. Morreale, D. O. Carvalho, S. Stenhouse, A. M. Lloyd, D. F. Hoel and D. A. Hahn, Journal of Medical Entomology, 2023-06-21 13:03:55.
The yellow fever mosquito, Aedes aegypti L., can transmit several pathogens responsible for human diseases. With insecticide resistance development becoming a concern, alternative control strategies are needed for Ae. aegypti. Sterile insect technique (SIT) is an increasingly popular option being explored. However, logistical issues in mass production and sterilization make it difficult to maintain a SIT program. Male mosquitoes are typically irradiated as pupae because this is the earliest developmental point at which females can be separated from males, but asynchrony in pupation and high variability in pupal responses to irradiation based on pupal age make it difficult to sterilize mass quantities of pupae on a regular schedule in a rearing facility. Young adult mosquitoes have wider windows for irradiation sterilization than pupae, which can allow facilities to have fixed schedules for irradiation. We produced a workflow for adult Ae. aegypti irradiation in a mosquito control district with an operational SIT program that currently irradiates pupae. The impacts of chilling, compaction, and radiation dose on survival were all assessed before combining them into a complete adult irradiation protocol. Males chilled up to 16 h prior to compaction and compacted to 100 males/cm3 during radiation resulted in low mortality. Males irradiated as adults had increased longevity and similar sterility compared to males irradiated as pupae. Additionally, males sterilized as adults were more sexually competitive than males sterilized as pupae. Thus, we have shown that irradiating adult males can be a viable option to increase the efficiency of this operational mosquito SIT program.
Effects of radiation on the fitness, sterility and arbovirus susceptibility of a Wolbachia-free Aedes albopictus strain for use in the Sterile Insect Technique
25867D. J. Zhang, S. Yan, H. Yamada, Y. Wu, G. Wang, Q. D. Feng, D. Paerhande, H. Maiga, J. Bouyer, J. Qian, Z. D. Wu and X. Y. Zheng, Pest Management Science, 2023-06-15 08:49:29.
BACKGROUND: The sterile insect technique (SIT) is a green and species-specific insect pest control technique that suppresses target populations by releasing factory-reared, radio-sterilized males into the wild. Once released, it is important to be able to distinguish the released males from the wild males for monitoring purposes. Several methods to mark the sterile males exist. However, most have limitations due to monetary, process efficiency, or insect quality. Aedes albopictus is naturally infected with Wolbachia at a high prevalence. Therefore, the elimination of Wolbachia can serve as a biomarker to distinguish the factory-reared male mosquitoes from wild conspecifics. RESULTS: In this study, a Wolbachia-free Ae. albopictus GT strain was developed and its fitness evaluated, which was found to be comparable to the wild GUA strain. In addition, GT male mosquitoes were irradiated at the adult stage and a dose of 20 Gy or more induced over 99% sterility. Moreover, a dose of 30 Gy (almost completely sterilizing male and female mosquitoes) had limited effects on the mating competitiveness of GT males and vector competence of GT females, respectively. However, radiation reduced mosquito longevity, regardless of its sex. CONCLUSION: Our results indicated that the Ae. albopictus GT strain can be distinguished from the wild mosquitoes based on Wolbachia status and shows similar fitness, radio-sensitivity and arbovirus susceptibility to the GUA strain, indicating that it is feasible to use the GT strain to suppress Ae. albopictus populations for SIT programmes. This article is protected by copyright. All rights reserved.
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.
Scientists in Tahiti prepare to release sterilized mosquitoes to control dengue
26192F. Fouque, WHO TDR, 2023-05-16 12:42:52.
Scientists in Tahiti have launched a research project to test the Sterile Insect Technique (SIT) in French Polynesia, where the impact of the technology on dengue transmission will be measured for the first time. This is part of a global research initiative supported by TDR, (the Special Programme for Research and Training in Tropical Diseases), the International Atomic Energy Agency (IAEA), the World Health Organization (WHO), and the U.S. Centers for Disease Control and Prevention (CDC), to trial innovative, environmentally friendly solutions to disease control.
Genetically Engineered Mosquito experiment in California’s Central Valley halted
25147H. Bourque, Friends of the Earth, 2023-05-12 14:52:46.
In a victory for environmentalists, scientists and vulnerable agricultural communities across California, the California Department of Pesticide Regulation (DPR) announced yesterday the withdrawal of a permit request for a mass release of experimental genetically engineered mosquitoes in the Central Valley. The withdrawal of the biotech corporation Oxitec’s request halts the controversial proposed release of billions of genetically engineered insects. Scientists and other experts in the field have raised concerns about Oxitec’s proposal to release genetically engineered mosquitoes due to inadequate scientific review and lack of appropriate and relevant regulations, pressuring the company to disclose data critical to assessing potential public health and environmental impacts.
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.
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.
Massive mosquito factory in Brazil aims to halt dengue
24984M. Lenharo, Nature, 2023-04-14 09:48:56.
The non-profit World Mosquito Program (WMP) has announced that it will release modified mosquitoes in many of Brazil’s urban areas over the next 10 years, with the aim of protecting up to 70 million people from diseases such as dengue. Researchers have tested the release of this type of mosquito — which carries a Wolbachia bacterium that stops the insect from transmitting viruses — in select cities in countries such as Australia, Brazil, Colombia, Indonesia and Vietnam. But this will be the first time that the technology is dispersed nationwide. A mosquito factory will be built in a location yet to be determined in Brazil to supply the WMP’s ambitious initiative, in partnership with the Oswaldo Cruz Foundation (Fiocruz), a Brazilian public science institution in Rio de Janeiro. The facility should begin operating in 2024 and will produce up to five billion mosquitoes per year. “This will be the biggest facility in the world” to produce Wolbachia-infected mosquitoes, says Scott O’Neill, a microbiologist at Monash University in Melbourne, Australia, and head of the WMP. “And it will allow us in a short period of time to cover more people than in any other country.” Brazil has one of the highest rates of dengue infection in the world, reporting more than two million cases in 2022.Despite the positive results from past mosquito releases, researchers expect that it will be challenging to operate the technology at such a massive scale.
Dengue Exposure and Wolbachia wMel Strain Affects the Fertility of Quiescent Eggs of Aedes aegypti
25102M. T. Petersen, D. Couto-Lima, G. A. Garcia, M. G. Pavan, M. R. David and R. Maciel-de-Freitas, Viruses, 15. 2023-04-12 10:20:54.
(1) Background: The deployment of the bacterium Wolbachia to reduce arbovirus transmission is ongoing in several countries worldwide. When Wolbachia-carrying Aedes aegypti are released and established in the field, females may feed on dengue-infected hosts. The effects of simultaneous exposure on life-history traits of Ae. aegypti to Wolbachia wMel strain and dengue-1 virus DENV-1 remain unclear. (2) Methods: We monitored 4 groups (mosquitoes with either DENV-1 or Wolbachia, coinfected with DENV-1 and Wolbachia, as well as negative controls) to estimate Ae. aegypti survival, oviposition success, fecundity, collapsing and fertility of quiescent eggs for 12 weeks. (3) Results: Neither DENV-1 nor Wolbachia had a significant impact on mosquito survival nor on mosquito fecundity, although the last parameter showed a tendency to decrease with ageing. There was a significant decrease in oviposition success in individuals carrying Wolbachia. Wolbachia infection and storage time significantly increased egg collapse parameter on the egg viability assay, while DENV-1 had a slight protective effect on the first four weeks of storage. (4) Conclusions: Despite limitations, our results contribute to better understanding of the tripartite interaction of virus, bacteria and mosquito that may take place in field conditions and aid in guaranteeing the Wolbachia strategy success.
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.
DIPA-CRISPR gene editing in the yellow fever mosquito <em>Aedes aegypti</em> (Diptera: Culicidae)
24960S. Yu, T. Momoyo, O. Manabu, K. Hirotaka and D. Takaaki, bioRxiv, 2023.04.07.535996. 2023-04-07 10:28:04.
Current methods for gene editing in insects rely on embryonic microinjection, which can be challenging for non-specialist laboratories. Recently, an alternative method known as direct parental CRISPR (DIPA-CRISPR) was developed. This method involves injecting commercial Cas9 protein and single-guide RNA into adult females, which can efficiently introduce mutations into developing oocytes. However, its versatility has not been fully explored, particularly in insects that have the most derived, polytrophic meroistic ovaries. In this study, we successfully applied DIPA-CRISPR to the yellow fever mosquito Aedes aegypti, which has polytrophic meroistic ovaries. Following adult injection of Cas9 ribonucleoproteins (Cas9 RNPs) targeting the kynurenine 3-monooxygenase gene, we recovered gene-edited G0 individuals. Injection at 24 h after blood-feeding resulted in the highest gene editing efficiency (3.5%), confirming that a key parameter of DIPA-CRISPR is the stage in which the adult females are injected. Together with our previous study, we demonstrated that DIPA-CRISPR is applicable to all three types of insect ovaries (i.e., panoistic, telotrophic, and polytrophic), which indicates that DIPA-CRISPR is a generalizable approach for insect gene editing.Competing Interest StatementThe authors have declared no competing interest.
A bacterium against the tiger: further evidence of the potential of non-inundative releases of males with manipulated Wolbachia infection in reducing fertility of Aedes albopictus field populations in Italy
24966B. Caputo, R. Moretti, C. Virgillito, M. Manica, E. Lampazzi, G. Lombardi, P. Serini, V. Pichler, N. W. Beebe, A. Della Torre and M. Calvitti, Pest Management Science, 2023-04-06 10:42:30.
BACKGROUND: Incompatible Insect Technique (IIT) is a population suppression approach based on the release of males with manipulated Wolbachia infection inducing egg inviability in wild females. We here present results of multiple field releases of incompatible ARwP males carried out in 2019 in a 2.7-ha green area within urban Rome (Italy) to assess the effect on Ae. albopictus egg viability. Data are compared with results obtained in 2018, when the approach was tested for the first time in Europe. RESULTS: An average of 4,674 ARwP males were released weekly for 7 weeks, resulting in a mean ARwP/wild male ratio of 1.1:1 (versus 0.7:1 in 2018). Egg-viability dynamics in ovitraps significantly varied between Treated and Control Sites, with an estimated overall reduction of 35% (versus 15% in 2018). The estimated proportion of females classified as mated with ARwP males was 41.8% and the viability rate of eggs laid by these females (9.5%) was on average significantly lower than that of females only mated with wild males (87.8%); however, high variability in fertility was observed. Values of ARwP male competitiveness were 0.36 and 0.73 based on the overall viability rate of eggs in ovitraps and on female fertility, respectively, i.e. well above the conventional 0.2 threshold for an effective suppressive impact in the field. CONCLUSIONS: Results further support the potential of IIT as a tool to contribute to Ae. albopictus control in the urban context, stressing the need of larger field trials to evaluate the cost-efficacy of the approach in temperate regions.
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'.
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.
The sex pheromone heptacosane enhances the mating competitiveness of sterile Aedes aegypti males
24861L.-M. Wang, N. Li, M. Zhang, Q. Tang, H.-Z. Lu, Q.-Y. Zhou, J.-X. Niu, L. Xiao, Z.-Y. Peng, C. Zhang, M. Liu, D.-Q. Wang and S.-Q. Deng, Parasites and Vectors, 16:102. 2023-03-15 15:04:09.
Aedes aegypti is a vector that transmits various viral diseases, including dengue and Zika. The radiation-based sterile insect technique (SIT) has a limited effect on mosquito control because of the difficulty in irradiating males without reducing their mating competitiveness. In this study, the insect sex pheromone heptacosane was applied to Ae. aegypti males to investigate whether it could enhance the mating competitiveness of irradiated males. Heptacosane was smeared on the abdomens of Ae. aegypti males that were allowed to mate with untreated virgin females. The insemination rate was used to assess the attractiveness of heptacosane‑treated males to females. The pupae were irradiated with different doses of X‑rays and γ‑rays, and the emergence, survival time, egg number, and hatch rate were detected to find the optimal dose of X‑ray and γ‑ray radiation. The males irradiated at the optimal dose were smeared with heptacosane, released in different ratios with untreated males, and mated with females. The effect of heptacosane on the mating competitiveness of irradiated mosquitoes was then evaluated by the hatch rate, induced sterility, and mating competitiveness index. Results Applying heptacosane to Ae. aegypti males significantly increased the insemination rate of females by 20%. Pupal radiation did not affect egg number but significantly reduced survival time and hatch rate. The emergence of the pupae was not affected by X‑ray radiation but was affected by γ‑ray radiation. Pupae exposed to 60 Gy X‑rays and 40 Gy γ‑rays were selected for subsequent experiments. After 60 Gy X‑ray irradiation or 40 Gy γ‑ray irradiation, the average hatch rate was less than 0.1%, and the average survival time was more than 15 days. Moreover, at the same release ratio, the hatch rate of the irradiated group perfumed with heptacosane was lower than that of the group without heptacosane. Conversely, the male sterility and male mating competitiveness index were significantly increased due to the use of heptacosane.
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.
Galapagos to receive male mosquitoes for vector control in Ecuador
24835A. R. Martin, Prensa Latina, 2023-03-07 08:39:27.
The Galapagos Islands will receive 100,000 sterile male mosquitoes as part of a new vector control strategy in Ecuador, the Center for Research in Infectious and Vector Diseases (CIREV) announced. Reducing the Aedes aegypti in Ecuador is in charge of the National Institute for Public Health Research (INSPI), and will start off the experimental phase coming Friday, March 10. The research, which started in 2017, is co-financed by the Technical Cooperation Program of the International Atomic Energy Agency
Analysing inhibition of dengue virus in Wolbachia-infected mosquito cells following the removal of Wolbachia
24822M. Hussain, K. Etebari and S. Asgari, Virology, 581:48-55. 2023-03-03 10:30:05.
Wolbachia pipientis is known to block replication of positive sense RNA viruses. Previously, we created an Aedes aegypti Aag2 cell line (Aag2.wAlbB) transinfected with the wAlbB strain of Wolbachia and a matching tetracycline-cured Aag2.tet cell line. While dengue virus (DENV) was blocked in Aag2.wAlbB cells, we found significant inhibition of DENV in Aag2.tet cells. RNA-Seq analysis of the cells confirmed removal of Wolbachia and lack of expression of Wolbachia genes that could have been due to lateral gene transfer in Aag2.tet cells. However, we noticed a substantial increase in the abundance of phasi charoen-like virus (PCLV) in Aag2.tet cells. When RNAi was used to reduce the PCLV levels, DENV replication was significantly increased. Further, we found significant changes in the expression of antiviral and proviral genes in Aag2.tet cells. Overall, the results reveal an antagonistic interaction between DENV and PCLV and how PCLV-induced changes could contribute to DENV inhibition.
Genome evolution of dengue virus serotype 1 under selection by Wolbachia pipientis in Aedes aegypti mosquitoes
27978D. Thi Hue Kien, K. Edenborough, D. da Silva Goncalves, T. Thuy Vi, E. Casagrande, H. Thi Le Duyen, V. Thi Long, L. Thi Dui, V. Thi Tuyet Nhu, N. Thi Giang, H. Thi Xuan Trang, E. Lee, I. a. Donovan-Banfield, H. Thi Thuy Van, N. Minh Nguyet, N. Thanh Phong, Virus Evolution, 9:vead016. 2023-03-03 07:47:19.
The introgression of antiviral strains of Wolbachia into Aedes aegypti mosquito populations is a public health intervention for the control of dengue. Plausibly, dengue virus (DENV) could evolve to bypass the antiviral effects of Wolbachia and undermine this approach. Here, we established a serial-passage system to investigate the evolution of DENV in Ae. aegypti mosquitoes infected with the wMel strain of Wolbachia. Using this system, we report on virus genetic outcomes after twenty passages of serotype 1 of DENV (DENV-1). An amino acid substitution, E203K, in the DENV-1 envelope protein was more frequently detected in the consensus sequence of virus populations passaged in wMel-infected Ae. aegypti than wild-type counterparts. Positive selection at residue 203 was reproducible; it occurred in passaged virus populations from independent DENV-1-infected patients and also in a second, independent experimental system. In wild-type mosquitoes and human cells, the 203K variant was rapidly replaced by the progenitor sequence. These findings provide proof of concept that wMel-associated selection of virus populations can occur in experimental conditions. Field-based studies are needed to explore whether wMel imparts selective pressure on DENV evolution in locations where wMel is established.
Wolbachia pipientis infections in populations of Aedes albopictus in the city of València (Spain): implications for mosquito control
24830R. Bueno-Marí, R. Domínguez-Santos, M. Trelis, E. Garrote-Sánchez, M. Cholvi, F. Quero de Lera, M. Khoubbane, A. Marcilla and R. Gi, Revista Española de Salud Pública, 97. 2023-03-02 16:20:52.
OBJECTIVE: The presence of Aedes albopictus, of high sanitary and social impact, was first reported in Valencia (Eastern Spain) in 2015. Innovative tools for its control include the use of the endosymbiotic bacterium Wolbachia pipientis. The release of mosquito males infected with the wPip strain, has proven very promising for large-scale Incompatible Insect Technique (IIT) applications. Before this strategy can be implemented in Valencia, it is important to know whether the natural local mosquito populations are Wolbachia-infected and, if so, identifying the infecting strains/supergroups, these being the objectives of the present work. METHODS: Eggs were collected from the 19 districts of the València city between May and October 2019. A total of 50 lab-reared adult Ae. albopictus individuals were processed and analyzed for Wolbachia detection and molecular characterization. These actions took place within the framework of a collaboration established with the Department of Health and Consumer Affairs of the city council of Valencia. Fisher's exact test was used to detect the statistical significance of the differences between groups. RESULTS: Our study revealed that 94% of the analyzed samples were naturally infected with Wolbachia. Both wAlbA and wAlbB supergroups were identified, with most samples (72% of the infected ones) carrying co-infections. CONCLUSIONS: These data provide the first characterization of the Wolbachia presence in natural populations of Ae. albopictus in the Mediterranean area of Spain. This information is relevant to evaluate the potential use of Wolbachia strains in order to achieve the suppression of the Asian tiger mosquito populations through massive release of artificially-infected males.
Satellite Rearing of Aedes Mosquito Eggs: Synchronized Empirical Test of a Novel Mass Rearing Model
24981K. L. Dobson, K. Blore, J. A. Henke, K. Y. Hung, T. Morgan, T. Posey, S. Sun, O. Sypes, N. P. Tremblay and S. L. Dobson, J Am Mosq Control Assoc, 39:12-17. 2023-03-01 09:41:35.
Mosquito suppression strategies based on "rear and release" of male mosquitoes are attracting renewed interest from governments, municipalities, and private businesses. These include irradiation-based sterile insect technique, Wolbachia-based technologies, and genetic modification. Each of these approaches requires the mass rearing and release of adult male mosquitoes, which typically is accomplished via a rearing facility near the release site. Although some release programs have relied on centralized rearing and shipment of adult males, adult male mosquitoes are relatively fragile, and their fitness can be diminished by temperature fluctuations, humidity, nutritional deficiencies, and other stresses that occur during shipment. Furthermore, expensive, expedited shipment is typically used to maximize the amount of adult lifetime in the field following the release. In contrast, Aedes aegypti and Ae. albopictus eggs can be desiccated and stored for long periods. They are small, and many millions of eggs can be shipped without specialized environmental conditions and using less expensive means. Here we examine a model in which mosquito eggs are centrally produced and then mailed to satellite rearing facilities. As a control, a replicate set of eggs was reared at the factory of origin. At each of the rearing sites, cloud-based software was used to track and compare rearing at the different locations. The results demonstrate similar rearing outcomes (i.e., egg hatch, immature development, and number of adult males) at each of the different sites for both species. We discuss the outcome in relation to downstream applications and potential future studies.
From the Lab to the Field: Long-Distance Transport of Sterile Aedes Mosquitoes
24750H. Maïga, M. T. Bakhoum, W. Mamai, G. Diouf, N. S. Bimbilé Somda, T. Wallner, C. Martina, S. S. Kotla, O. B. Masso, H. Yamada, B. B. D. Sow, A. G. Fall and J. Bouyer, Insects, 14. 2023-02-18 19:03:39.
Pilot programs of the sterile insect technique (SIT) against Aedes aegypti may rely on importing significant and consistent numbers of high-quality sterile males from a distant mass rearing factory. As such, long-distance mass transport of sterile males may contribute to meet this requirement if their survival and quality are not compromised. This study therefore aimed to develop and assess a novel method for long-distance shipments of sterile male mosquitoes from the laboratory to the field. Different types of mosquito compaction boxes in addition to a simulation of the transport of marked and unmarked sterile males were assessed in terms of survival rates/recovery rates, flight ability and morphological damage to the mosquitoes. The novel mass transport protocol allowed long-distance shipments of sterile male mosquitoes for up to four days with a nonsignificant impact on survival (>90% for 48 h of transport and between 50 and 70% for 96 h depending on the type of mosquito compaction box), flight ability, and damage. In addition, a one-day recovery period for transported mosquitoes post-transport increased the escaping ability of sterile males by more than 20%. This novel system for the long-distance mass transport of mosquitoes may therefore be used to ship sterile males worldwide for journeys of two to four days. This study demonstrated that the protocol can be used for the standard mass transport of marked or unmarked chilled Aedes mosquitoes required for the SIT or other related genetic control programs.
Evaluating the mating competency of genetically modified male mosquitoes in laboratory conditions
28160B. Contreras, Z. N. Adelman and K. Chae, Frontiers in Tropical Diseases, 4. 2023-02-13 12:01:23.
Efforts to eradicate mosquito-borne diseases have increased the demand for genetic control strategies, many of which involve the release of genetically modified (GM) mosquito males into natural populations. The first hurdle for GM males is to compete with their wild-type counterparts for access to females. Here, we introduce an eye color-based mating assay, in which both Lvp wild-type and kynurenine 3-monooxygenase (kmo)-null males compete for access to kmo-null females, and therefore the eye color phenotype (black or white) of the progeny is dependent on the parental mating pair. A series of tests addressed that male mating competitiveness between the two strains can significantly be influenced by adult density, light intensity, and mating duration. Interestingly, the mating competitiveness of males was not correlated with body size, which was negatively influenced by a high larval density. Lastly, this eye color-associated assay was applied to characterize GM mosquitoes in their mating competitiveness, establishing this method as a fast and precise way of benchmarking this fitness parameter for laboratory-raised males.
When less is more: accounting for overcompensation in mosquito SIT projects
24717J. Bouyer, Trends in Parasitology, 2023-02-08 10:14:35.
Compensation and overcompensation under field conditions are confirmed in Aedes mosquitoes recently by Evans et al.: equal or increased densities of emerging adults may thus result from reduced larval densities. Here the consequences when applying the sterile insect technique and provide recommendations to avoid counterproductive effects are discussed.
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.
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.
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.
Impact of randomised wmel Wolbachia deployments on notified dengue cases and insecticide fogging for dengue control in Yogyakarta City
24619C. Indriani, S. K. Tanamas, U. Khasanah, M. R. Ansari, Rubangi, W. Tantowijoyo, R. A. Ahmad, S. M. Dufault, N. P. Jewell, A. Utarini, C. P. Simmons and K. L. Anders, Glob Health Action, 16:2166650. 2023-01-26 09:27:00.
BACKGROUND: Releases of Wolbachia (wMel)-infected Aedes aegypti mosquitoes significantly reduced the incidence of virologically confirmed dengue in a previous cluster randomised trial in Yogyakarta City, Indonesia. Following the trial, wMel releases were extended to the untreated control areas, to achieve city-wide coverage of Wolbachia. OBJECTIVE: In this predefined analysis, we evaluated the impact of the wMel deployments in Yogyakarta on dengue hemorrhagic fever (DHF) case notifications and on the frequency of perifocal insecticide spraying by public health teams. METHODS: Monthly counts of DHF cases notified to the Yogyakarta District Health Office between January 2006 and May 2022 were modelled as a function of time-varying local wMel treatment status (fully- and partially-treated vs untreated, and by quintile of wMel prevalence). The frequency of insecticide fogging in wMel-treated and untreated areas was analysed using negative binomial regression. RESULTS: Notified DHF incidence was 83% lower in fully treated vs untreated periods (IRR 0.17 [95% CI 0.14, 0.20]), and 78% lower in areas with 80-100% wMel prevalence compared to areas with 0-20% wMel (IRR 0.23 [0.17, 0.30]). A similar intervention effect was observed at 60-80% wMel prevalence as at 80-100% prevalence (76% vs 78% efficacy, respectively). Pre-intervention, insecticide fogging occurred at similar frequencies in areas later randomised to wMel-treated and untreated arms of the trial. After wMel deployment, fogging occurred significantly less frequently in treated areas (IRR 0.17 [0.10, 0.30]). CONCLUSIONS: Deployments of wMel-infected Aedes aegypti mosquitoes resulted in an 83% reduction in the application of perifocal insecticide spraying, consistent with lower dengue case notifications in wMel-treated areas. These results show that the Wolbachia intervention effect demonstrated previously in a cluster randomised trial was also measurable from routine surveillance data.
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].
Wolbachia RNase HI contributes to virus blocking in the mosquito Aedes aegypti
24468M. Hussain, G. Zhang, M. Leitner, L. M. Hedges and S. Asgari, iScience, 26:105836. 2023-01-15 08:41:00.
The endosymbiotic bacterium Wolbachia pipientis blocks replication of several arboviruses in transinfected Aedes aegypti mosquitoes. However, the mechanism of virus blocking remains poorly understood. Here, we characterized an RNase HI gene from Wolbachia, which is rapidly induced in response to dengue virus (DENV) infection. Knocking down w RNase HI using antisense RNA in Wolbachia-transinfected mosquito cell lines and A. aegypti mosquitoes led to increased DENV replication. Furthermore, overexpression of wRNase HI, in the absence of Wolbachia, led to reduced replication of a positive sense RNA virus, but had no effect on a negative sense RNA virus, a familiar scenario in Wolbachia-infected cells. Altogether, our results provide compelling evidence for the missing link between early Wolbachia-mediated virus blocking and degradation of viral RNA. These findings and the successful pioneered knockdown of Wolbachia genes using antisense RNA in cell line and mosquitoes enable new ways to manipulate and study the complex endosymbiont-host interactions.
Dynamics of an impulsive reaction-diffusion mosquitoes model with multiple control measures
24571Y. Li, H. Zhao and K. Wang, Mathematical Biosciences and Engineering, 20:775-806. 2023-01-14 08:34:08.
It is well-known that mosquito control is one of the effective methods to reduce and prevent the transmission of mosquito-borne diseases. In this paper, we formulate a reaction-diffusion impulsive hybrid model incorporating Wolbachia, impulsively spraying of insecticides, spatial heterogeneity, and seasonality to investigate the control of mosquito population. The sufficient conditions for mosquito extinction or successful Wolbachia persistence in a population of natural mosquitoes are derived. More importantly, we give the estimations of the spraying times of insecticides during a period for achieving the mosquito extinction and population replacement in a special case. A global attractivity of the positive periodic solution is analyzed under appropriate conditions. Numerical simulations disclose that spatial heterogeneity and seasonality have significant impacts on the design of mosquitoes control strategies. It is suggested to combine biological control and chemical pulse control under certain situations to reduce the natural mosquitoes. Further, our results reveal that the establishment of a higher level of population replacement depends on the strain type of the Wolbachia and the high initial occupancy of the Wolbachia-infected mosquitoes.
Effects of gamma radiation on the vector competence of Aedes aegypti (diptera: Culicidae) to transmit Zika virus
24462E. B. da Silva, C. M. de Mendonça, D. R. D. Guedes, M. H. S. Paiva, J. d. A. Mendonça, E. S. F. Dias, S. G. L. Florêncio, A. Amaral, A. M. Netto, C. F. J. A. Lopes and M. A. V. de Melo-Santos, Acta Tropica, 239:106831. 2023-01-11 08:27:34.
One of the limitations of the Sterile Insect Technique (SIT), conventionally performed by ionizing radiation, regards separating males from females, which is not 100% effective. Some irradiated females may be released together with males in the field at SIT. The present study aimed to evaluate the influence of ionizing radiation on the ability of Aedes aegypti mosquitoes to transmit the Zika virus after exposing female pupae to a 40 Gy of gamma radiation. The results suggest that the genetic damage induced by exposure of females to this dose level promotes their total sterility, but it does not influence their vector competence. However, our data point out that ionizing radiation may decrease the proportion of infective mosquitoes.
Sterility of Aedes albopictus by X-ray Irradiation as an Alternative to γ-ray Irradiation for the Sterile Insect Technique
24424L.-M. Wang, N. Li, C.-P. Ren, Z.-Y. Peng, H.-Z. Lu, D. Li, X.-Y. Wu, Z.-X. Zhou, J.-Y. Deng, Z.-H. Zheng, R.-Q. Wang, Y.-N. Du, D.-Q. Wang and S.-Q. Deng, Pathogens, 12. 2023-01-06 10:18:19.
The mosquito Aedes albopictus can transmit various arboviral diseases, posing a severe threat to human health. As an environmentally friendly method, sterile insect technology (SIT) is considered an alternative to traditional methods such as chemical pesticides to control Ae. albopictus. In SIT, the sterility of male mosquitoes can be achieved by γ-ray or X-ray radiation. Compared with γ-rays, X-rays are easier to obtain, cheaper, and less harmful. However, there is a lack of comparative assessment of these two types of radiation for SIT under the same controlled conditions. Here, we compared the effects of X-ray and γ-ray radiation on the sterility of Ae. albopictus males under laboratory-controlled conditions. Neither type of radiation affected the number of eggs but significantly reduced the survival time and hatch rate. The same dose of γ-rays caused a higher sterility effect on males than X-rays but had a more significant impact on survival. However, X-rays could achieve the same sterility effect as γ-rays by increasing the radiation dose. For example, X-rays of 60 Gy induced 99% sterility, similar to γ-rays of 40 Gy. In the test of male mating competitiveness, the induced sterility and the male mating competitiveness index were also identical at the same release ratio (sterile males/fertile males). At a release ratio of 7:1, nearly 80% of eggs failed to hatch. Sterile males produced by X-ray and γ-ray radiation had similar male competitiveness in competition with field males. In conclusion, a higher dose of X-rays is required to achieve the same sterility effect, compared to γ-rays. When γ-rays are not readily available, high-dose X-rays can be used instead. This study provides data supporting the selection of more suitable radiation for the field release of sterile male mosquitoes.
Survival-Larval Density Relationships in the Field and Their Implications for Control of Container-Dwelling Aedes Mosquitoes
24714K. G. Evans, Z. R. Neale, B. Holly, C. C. Canizela and S. A. Juliano, Insects, 14. 2022-12-23 10:10:37.
Population density can affect survival, growth, development time, and adult size and fecundity, which are collectively known as density-dependent effects. Container Aedes larvae often attain high densities in nature, and those densities may be reduced when larval control is applied. We tested the hypothesis that density-dependent effects on survival are common and strong in nature and could result in maximal adult production at intermediate densities for Aedes aegypti, Aedes albopictus, and Aedes triseriatus. We surveyed naturally occurring densities in field containers, then introduced larvae at a similar range of densities, and censused the containers for survivors. We analyzed the survival-density relationships by nonlinear regressions, which showed that survival-density relationships vary among seasons, sites, and species. For each Aedes species, some sites and times yielded predictions that larval density reduction would yield the same (compensation), or more (overcompensation), adults than no larval density reduction. Thus, larval control targeting these Aedes species cannot always be assumed to yield a reduction in the number of adult mosquitoes. We suggest that mosquito control targeting larvae may be made more effective by: Imposing maximum mortality; targeting populations when larval abundances are low; and knowing the shape of the survival-density response of the target population.
Assessing the efficacy of male Wolbachia-infected mosquito deployments to reduce dengue incidence in Singapore: study protocol for a cluster-randomized controlled trial
24268J. Ong, S. H. Ho, S. X. H. Soh, Y. Wong, Y. Ng, K. Vasquez, Y. L. Lai, Y. X. Setoh, C. S. Chong, V. Lee, J. C. C. Wong, C. H. Tan, S. Sim, L. C. Ng and J. T. Lim, Trials, 23:1023. 2022-12-17 13:57:59.
The study is designed as a parallel, two-arm, non-blinded cluster-randomized (CR) controlled trial to be conducted in high-rise public housing estates in Singapore, an equatorial city-state. The aim is to determine whether large-scale deployment of male Wolbachia-infected Ae. aegypti mosquitoes can significantly reduce dengue incidence in intervention clusters. We will use the CR design, with the study area comprising 15 clusters with a total area of 10.9 km(2), covering approximately 722,204 residents in 1713 apartment blocks. Eight clusters will be randomly selected to receive the intervention, while the other seven will serve as non-intervention clusters. Intervention efficacy will be estimated through two primary endpoints:
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.
Oxitec’s mosquitoes are getting “friendly” with California
24109L. Patrick, The Sun Gazette, 2022-12-01 09:34:07.
Biotech company Oxitec is buzzing around Visalia, with the hopes of releasing their genetically engineered mosquitoes in Tulare County. Oxitec has one more hurdle to jump over in order to release their “friendly” Aedes aegypti mosquitoes in Tulare County, and that’s to gain the approval of the California Department of Pesticide Regulation (DPR). Though their attempts to release their GE mosquitoes in California have been met with both supportive and hesitant reactions from different state agencies and environmental groups, Oxitec’s Dr. Kevin Gorman said the technology has been researched and reviewed with “much scrutiny,” despite claims that the mosquitoes are ineffective or hazardous. “We have a biological approach to managing pest insects, and the biological approach is a mating-based technology. It’s very targeted, it only affects the species that [they’re] mating with,” Gorman said. “Not only is it environmentally safe, it’s effective.” The male GE mosquitoes from Oxitec have been engineered with a self-limiting gene, and this gene infects wild female mosquitoes to prevent them from reproducing female offspring. This leaves only male mosquitoes in the gene pool, according to Gorman. Female mosquitoes are targeted since they are the only ones that bite, and therefore capable of transmitting diseases. The engineered males will only mate with Aedes aegypti females, and do not leave an environmental footprint, according to Gorman. The release of these mosquitoes is supposed to reduce the natural population of the invasive mosquito, which are known to carry diseases such as dengue, chikungunya, Zika, yellow fever and others.
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.
Developing radiation-based sterile insect technique (SIT) for controlling Aedes aegypti: identification of a sterilizing dose
24028C. Chen, R. L. Aldridge, S. Gibson, J. Kline, V. Aryaprema, W. Qualls, R.-d. Xue, L. Boardman, K. J. Linthicum and D. A. Hahn, Pest Management Science, 2022-11-24 09:37:31.
Abstract Background The sterile insect technique (SIT) is emerging as a tool to supplement traditional pesticide-based control of Aedes aegypti, a prominent mosquito vector of microbes that have increased the global burden of human morbidity and mortality over the past 50?years. SIT relies on rearing, sterilizing, and releasing large numbers of male mosquitoes that will mate with fertile wild females, thus reducing production of offspring from the target population. In this study, we investigated the effects of ionizing radiation (gamma) on male and female survival, longevity, mating behavior, and sterility of Ae. aegypti in a dose-response design. This work is a first step towards developing an operational SIT field suppression program against Ae. aegypti in St. Augustine, Florida, USA. Results Exposing late-stage pupae to 50 Gy of radiation yielded 99% male sterility while maintaining similar survival of pupae to adult emergence, adult longevity, and male mating competitiveness compared to unirradiated males. Females were completely sterilized at 30 Gy, and when females were dosed with 50 Gy, they had a lower incidence of blood feeding than unirradiated females. Conclusion Our work suggests that an ionizing radiation dose of 50 Gy should be used for future development of operational SIT in our program area because at this dose males are 99% sterile while maintaining mating competitiveness against unirradiated males. Furthermore, females that might be accidentally released with sterile males due to errors in sex sorting are also sterile and less likely to blood feed than unirradiated females at our 50 Gy dose.
A CRISPR endonuclease gene drive reveals distinct mechanisms of inheritance bias
24021S. A. N. Verkuijl, E. Gonzalez, M. Li, J. X. D. Ang, N. P. Kandul, M. A. E. Anderson, O. S. Akbari, M. B. Bonsall and L. Alphey, Nature Communications, 13:7145. 2022-11-21 09:45:13.
CRISPR/Cas gene drives can bias transgene inheritance through different mechanisms. Homing drives are designed to replace a wild-type allele with a copy of a drive element on the homologous chromosome. In Aedes aegypti, the sex-determining locus is closely linked to the white gene, which was previously used as a target for a homing drive element (wGDe). Here, through an analysis using this linkage we show that in males inheritance bias of wGDe did not occur by homing, rather through increased propagation of the donor drive element. We test the same wGDe drive element with transgenes expressing Cas9 with germline regulatory elements sds3, bgcn, and nup50. We only find inheritance bias through homing, even with the identical nup50-Cas9 transgene. We propose that DNA repair outcomes may be more context dependent than anticipated and that other previously reported homing drives may, in fact, bias their inheritance through other mechanisms.
Independent evaluation of Wolbachia infected male mosquito releases for control of Aedes aegypti in Harris County, Texas, using a Bayesian abundance estimator
23969S. Lozano, K. Pritts, D. Duguma, C. Fredregill and R. Connelly, PLOS Neglected Tropical Diseases, 16:e0010907. 2022-11-14 12:37:36.
Among disease vectors, Aedes aegypti (L.) (Diptera: Culicidae) is one of the most insidious species in the world. The disease burden created by this species has dramatically increased in the past 50 years, and during this time countries have relied on pesticides for control and prevention of viruses borne by Ae. aegypti. The small number of available insecticides with different modes of action had led to increases in insecticide resistance, thus, strategies, like the “Incompatible Insect Technique” using Wolbachia’s cytoplasmic incompatibility are desirable. We evaluated the effect of releases of Wolbachia infected Ae. aegypti males on populations of wild Ae. aegypti in the metropolitan area of Houston, TX. Releases were conducted by the company MosquitoMate, Inc. To estimate mosquito population reduction, we used a mosquito abundance Bayesian hierarchical estimator that accounted for inefficient trapping. MosquitoMate previously reported a reduction of 78% for an intervention conducted in Miami, FL. In this experiment we found a reduction of 93% with 95% credibility intervals of 86% and 96% after six weeks of continual releases. A similar result was reported by Verily Life Sciences, 96% [94%, 97%], in releases made in Fresno, CA.
Influence of public hesitancy and receptivity on reactive behaviours towards releases of male Wolbachia-Aedes mosquitoes for dengue control
23860M. O. Lwin, Z. Ong, C. Panchapakesan, A. Sheldenkar, L. T. Soh, I. Chen, X. Li, W. Niah, K. Vasquez, S. Sim and L.-C. Ng, PLOS Neglected Tropical Diseases, 16:e0010910. 2022-11-11 10:06:20.
Singapore, a highly urbanized Asian tropical country that experiences periodic dengue outbreaks, is piloting field releases of male Wolbachia-carrying Aedes aegyptimosquitoes with the aim of suppressing urban populations of the primary dengue vector Aedes aegypti. This study proposes and assesses a model to explain the roles of hesitancy and receptivity towards Project Wolbachia–Singapore in influencing reactive mosquito prevention behaviors (reactive behaviors) towards the release of Wolbachia-Aedes mosquitoes for residents living in the release sites. Interestingly, both hesitancy and receptivity predicted greater instances of reactive behaviors. The model also examines the roles of general knowledge about Wolbachia technology, perceived severity of mosquito bites, perceived density of mosquitoes, and social responsibility as predictors of hesitancy, receptivity, and reactive behaviors towards the release of Wolbachia-Aedes mosquitoes. Hesitancy towards the project mediated the effects of general knowledge, perceived severity of mosquito bites, and perceived density of mosquitoes on reactive behaviors towards the releases, although receptivity towards the project did not. Having less knowledge about Project Wolbachia–Singapore was associated with higher hesitancy towards the project and higher likelihood of performing reactive behaviors towards the releases. Individuals who perceive mosquito bites to be more severe and think that there are more mosquitoes in their living environments were also more likely to be hesitant about the project and practice reactive behaviors. However, both hesitancy and receptivity towards the project mediated the effect of social responsibility on reactive behaviors. Receptivity towards the project was driven by social responsibility, which was also associated with reduced hesitancy towards the project. Our findings suggest that, to address the hesitancy reported by a minority of participants, future outreach efforts should focus on strengthening the public’s sense of social responsibility
Wolbachia inhibits ovarian formation and increases blood feeding rate in female Aedes aegypti
23858M.-J. Lau, P. A. Ross, N. M. Endersby-Harshman, Q. Yang and A. A. Hoffmann, PLOS Neglected Tropical Diseases, 16:e0010913. 2022-11-11 09:59:48.
Author summary Wolbachia bacteria reduce the transmission of dengue and other arboviruses transmitted by their mosquito hosts once they have invaded host populations. This invasion process is being undertaken in Aedes aegypti mosquito populations throughout the world but can be slowed by deleterious fitness costs that the Wolbachia bacteria have on their mosquito hosts. Here we investigate in detail a recently identified cost where one of the Wolbachia strains being used in invasions causes infertility in females when the females develop from eggs that have been stored for a period. We show that slowed larval development (through food reduction) can cause the same phenomenon and that the emerged females lack functional ovaries. These infertile females also take blood meals more often. The results have implications for the successful invasion of Wolbachia under ecological circumstances where the mosquito eggs have to persist in the absence of water for a period and where larval food is limiting.
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.
Monotonicity properties arising in a simple model of Wolbachia invasion for wild mosquito populations
24568D. Vicencio, O. Vasilieva and P. Gajardo, Mathematical Biosciences and Engineering, 20:1148-1175. 2022-10-25 08:23:57.
Using tools borrowed from monotone dynamical system theory, in the proposed model, we prove the existence of an invariant threshold manifold that allows us to provide practical recommendations for performing single and periodic releases of Wolbachia-carrying mosquitoes, seeking the eventual elimination of wild insects that are capable of transmitting infections to humans. We illustrate these findings with numerical simulations using parameter values corresponding to the wMelPop strain of Wolbachia that is considered the best virus blocker but induces fitness loss in its carriers. In these tests, we considered multiple scenarios contrasting a periodic release strategy against a strategy with a single inundative release, comparing their effectiveness. Our study is presented as an expository and mathematically accessible tool to study the use of Wolbachia-based biocontrol versus more complex models.
New self-sexing Aedes aegypti strain eliminates barriers to scalable and sustainable vector control for governments and communities in dengue-prone environments
23796S. A. M. Spinner, Z. H. Barnes, A. M. Puinean, P. Gray, T. Dafa’alla, C. E. Phillips, C. Nascimento de Souza, T. F. Frazon, K. Ercit, A. Collado, N. Naish, E. Sulston, G. C. Ll. Phillips, K. K. Greene, M. Poletto, B. D. Sperry, S. A. Warner, N. R. Rose, G, Frontiers in Bioengineering and Biotechnology, 10. 2022-10-25 07:35:02.
For more than 60 years, efforts to develop mating-based mosquito control technologies have largely failed to produce solutions that are both effective and scalable, keeping them out of reach of most governments and communities in disease-impacted regions globally. High pest suppression levels in trials have yet to fully translate into broad and effective Aedes aegypti control solutions. Two primary challenges to date–the need for complex sex-sorting to prevent female releases, and cumbersome processes for rearing and releasing male adult mosquitoes–present significant barriers for existing methods. As the host range of Aedes aegypti continues to advance into new geographies due to increasing globalisation and climate change, traditional chemical-based approaches are under mounting pressure from both more stringent regulatory processes and the ongoing development of insecticide resistance. It is no exaggeration to state that new tools, which are equal parts effective and scalable, are needed now more than ever. This paper describes the development and field evaluation of a new self-sexing strain of Aedes aegypti that has been designed to combine targeted vector suppression, operational simplicity, and cost-effectiveness for use in disease-prone regions. This conditional, self-limiting trait uses the sex-determination gene doublesex linked to the tetracycline-off genetic switch to cause complete female lethality in early larval development. With no female progeny survival, sex sorting is no longer required, eliminating the need for large-scale mosquito production facilities or physical sex-separation. In deployment operations, this translates to the ability to generate multiple generations of suppression for each mosquito released, while being entirely self-limiting. To evaluate these potential benefits, a field trial was carried out in densely-populated urban, dengue-prone neighbourhoods in Brazil, wherein the strain was able to suppress wild mosquito populations by up to 96%, demonstrating the utility of this self-sexing approach for biological vector control. In doing so, it has shown that such strains offer the critical components necessary to make these tools highly accessible, and thus they harbour the potential to transition mating-based approaches to effective and sustainable vector control tools that are within reach of governments and at-risk communities who may have only limited resources.
Assessing single-locus CRISPR/Cas9-based gene drive variants in the mosquito Aedes aegypti via single generation crosses and modeling
23756W. Reid, A. E. Williams, I. Sanchez-Vargas, J. Lin, R. Juncu, K. E. Olson and A. W. E. Franz, G3 Genes|Genomes|Genetics, 2022-10-17 06:25:18.
Critical to the design of a single-locus autonomous GD is that the selected genomic locus is amenable to both GD and appropriate expression of the antiviral effector. In our study, we used reverse engineering to target two intergenic genomic loci, which had previously shown to be highly permissive for antiviral effector gene expression, and we further investigated the use of three promoters (nanos, β2-tubulin, or zpg) for Cas9 expression. We then quantified the accrual of insertions or deletions (indels) after single generation crossings, measured maternal effects, and assessed fitness costs associated with the various transgenic lines to model the rate of GD fixation. Overall, MGDrivE modeling suggested that when an autonomous GD is placed into an intergenic locus, the GD system will eventually be blocked by the accrual of GD blocking resistance alleles and ultimately be lost in the population. Moreover, while genomic locus and promoter selection were critically important for the initial establishment of the autonomous GD, it was the fitness of the GD line that most strongly influenced the persistence of the GD in the simulated population. As such, we propose that when autonomous CRISPR/Cas9 based GD systems are anchored in an intergenic locus, they temporarily result in a strong population replacement effect, but as GD-blocking indels accrue, the GD becomes exhausted due to the fixation of CRISPR resistance alleles.
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.
Wolbachia wAlbB inhibit dengue and Zika infection in the mosquito Aedes aegypti with an Australian background
23714L. E. Hugo, G. Rašić, A. J. Maynard, L. Ambrose, C. Liddington, C. J. E. Thomas, N. S. Nath, M. Graham, C. Winterford, B. M. C. R. Wimalasiri-Yapa, Z. Xi, N. W. Beebe and G. J. Devine, PLOS Neglected Tropical Diseases, 16:e0010786. 2022-10-13 06:27:20.
Biological control of mosquito vectors using the endosymbiotic bacteria Wolbachia is an emerging strategy for the management of human arboviral diseases. We recently described the development of a strain of Aedes aegypti infected with the Wolbachia strain wAlbB (referred to as the wAlbB2-F4 strain) through simple backcrossing of wild type Australian mosquitoes with a wAlbB infected Ae. aegypti strain from the USA. Field releases of male wAlbB2-F4 mosquitoes resulted in the successful suppression of wild populations of mosquitoes in the trial sites by exploiting the strain’s Wolbachia-induced cytoplasmic incompatibility. We now demonstrate that the strain is resistant to infection by dengue and Zika viruses and is genetically similar to endemic Queensland populations. There was a fourfold reduction in the proportion of wAlbB2-F4 mosquitoes that became infected following a blood meal containing dengue 2 virus (16.7%) compared to wild type mosquitoes (69.2%) and a 6–7 fold reduction in the proportion of wAlbB2-F4 mosquitoes producing virus in saliva following a blood meal containing an epidemic strain of Zika virus (8.7% in comparison to 58.3% in wild type mosquitoes). Restriction-site Associated DNA (RAD) sequencing revealed that wAlbB2-F4 mosquitoes have > 98% Australian ancestry, confirming the successful introduction of the wAlbB2 infection into the Australian genomic background through backcrossing. Genotypic and phenotypic analyses showed the wAlbB2-F4 strain retains the insecticide susceptible phenotype and genotype of native Australian mosquitoes. We demonstrate that the Wolbachia wAlbB2-F4, in addition to being suitable for population suppression programs, can also be effective in population replacement programs given its inhibition of virus infection in mosquitoes. The ease at which a target mosquito population can be transfected with wAlbB2, while retaining the genotypes and phenotypes of the target population, shows the utility of this strain for controlling the Ae. aegypti mosquitoes and the pathogens they transmit.
Risk Assessment on the Release of Wolbachia-Infected Aedes aegypti in Yogyakarta, Indonesia
23707D. Buchori, A. Mawan, I. Nurhayati, A. Aryati, H. Kusnanto and U. K. Hadi, Insects, 13. 2022-10-12 08:16:52.
Wolbachia-infected Aedes aegypti is the latest technology that was developed to eliminate dengue fever. The Ministry of Research and Technology of the Republic of Indonesia (Kemenristekdikti) established an expert group to identify future potential risks that may occur over a period of 30 years associated with the release of Wolbachia-infected Ae. aegypti. The risk assessment consisted of identifying different hazards that may have impacts on humans and the environment. From the consensus among the experts, there were 56 hazards identified and categorized into 4 components, namely, ecological matters, efficacy in mosquito management, economic and sociocultural issues, and public health standards. There were 19 hazards in the ecological group. The overall likelihood in the ecology of the mosquito is very low (0.05), with moderate consequence (0.74), which resulted in negligible risk. For the efficacy in mosquito management group, there were 12 hazards that resulted in very low likelihood (0.11) with high consequence (0.85). The overall risk for mosquito management efficacy was very low (0.09). There were 14 hazards identified in the public health standard with very low likelihood (0.07), moderate consequence (0.50) and negligible risk (0.04). Lastly, 13 hazards were identified in the economic and sociocultural group with low likelihood (0.01) but of moderate consequence (0.5), which resulted in a very low risk (0.09). The risk severity level of the four components leading to the endpoint risk of “cause more harm” due to releasing Wolbachia-infected Ae. aegypti is negligible (0.01).
Wolbachia-Virus interactions and arbovirus control through population replacement in mosquitoes
23675T. H. Ant, M. V. Mancini, C. J. McNamara, S. M. Rainey and S. P. Sinkins, Pathogens and Global Health, 2022-10-07 08:27:10.
Following transfer into the primary arbovirus vector Aedes aegypti, several strains of the intracellular bacterium Wolbachia have been shown to inhibit the transmission of dengue, Zika, and chikungunya viruses, important human pathogens that cause significant morbidity and mortality worldwide. In addition to pathogen inhibition, many Wolbachia strains manipulate host reproduction, resulting in an invasive capacity of the bacterium in insect populations. This has led to the deployment of Wolbachia as a dengue control tool, and trials have reported significant reductions in transmission in release areas. Here, we discuss the possible mechanisms of Wolbachia-virus inhibition and the implications for long-term success of dengue control. We also consider the evidence presented in several reports that Wolbachia may cause an enhancement of replication of certain viruses under particular conditions, and conclude that these should not cause any concerns with respect to the application of Wolbachia to arbovirus control.
Fitness costs of Wolbachia shift in locally-adapted Aedes aegypti mosquitoes
23703P. A. Ross and A. A. Hoffmann, Environmental Microbiology, 2022-10-06 08:10:07.
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 found that the cost of wMel infection differed consistently between mosquitoes collected from different locations and became weaker across laboratory generations, suggesting environment-specific adaptation of mosquitoes to the wMel infection. Reciprocal crossing experiments show that differences in the cost of wMel to quiescent egg viability were mainly due to mosquito genetic background and not Wolbachia origin. 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 mosquito genetic backgrounds. The unexpected changes in fitness costs observed here suggest potential tradeoffs with undescribed fitness benefits of the wMel infection.
How We’re Reducing Disease With Genetically Modified Mosquitoes
23667V. Wise, HealthMatch, 2022-09-29 08:07:21.
We all know mosquitoes as those annoying insects we swat away from our faces. They carry diseases, so we don’t want them anywhere near us. There are over 200 types of wild mosquitoes bugging us across America and the U.S. territories. Approximately 12 types can spread disease, but most are “nuisance” mosquitoes, which don’t spread germs. Obviously, it’s hard to identify a tiny flying creature, so we need to keep them all away from us just in case. Aedes aegypti¹ is one of the most common mosquitoes in the U.S. that can spread disease. One of the best-known mosquito-borne diseases is malaria, but Aedes aegypti is associated with 54 viruses². West Nile virus, Zika, and dengue are just three diseases these mosquitoes transmit around the U.S With 1 in 150 people becoming seriously ill due to West Nile virus, sometimes fatally, what can we do to prevent mosquito bites?
Externalities modulate the effectiveness of the Wolbachia release programme
23611E. E. Ooi and A. Wilder-Smith, The Lancet Infectious Diseases, 2022-09-28 09:16:47.
Despite the remarkable outcome in Yogyakarta, the wMel approach also has some challenges. In particular, the extent to which ecological, weather, and other external factors influence the dissemination and establishment of wMel in complex urban environments remains unclear. Whether the high and sustained penetration rate of wMel and the efficacy in preventing dengue that was observed in Yogyakarta are readily reproducible in other regions of the world that are vulnerable to repeated outbreaks of such viral diseases is also unclear. We therefore welcome the study into the real-world effectiveness of large-scale wMel release in the urban setting of Rio de Janeiro.3 The study assessed the rate of wMel introgression at the neighbourhood level and its effect on the localised incidence of dengue and chikungunya. Mosquitoes were released over a 2·5-year period starting in August, 2017.
Estimating the effect of the wMel release programme on the incidence of dengue and chikungunya in Rio de Janeiro, Brazil: a spatiotemporal modelling study
23608G. Ribeiro dos Santos, B. Durovni, V. Saraceni, T. I. Souza Riback, S. B. Pinto, K. L. Anders, et al., The Lancet Infectious Diseases, 2022-09-28 09:07:02.
Summary Background Introgression of genetic material from species of the insect bacteria Wolbachia into populations of Aedes aegypti mosquitoes has been shown in randomised and non-randomised trials to reduce the incidence of dengue; however, evidence for the real-world effectiveness of large-scale deployments of Wolbachia-infected mosquitoes for arboviral disease control in endemic settings is still scarce. A large Wolbachia (wMel strain) release programme was implemented in 2017 in Rio de Janeiro, Brazil. We aimed to assess the effect of this programme on the incidence of dengue and chikungunya in the city. Methods 67 million wMel-infected mosquitoes were released across 28 489 locations over an area of 86·8 km2 in Rio de Janeiro between Aug 29, 2017 and Dec 27, 2019. Following releases, mosquitoes were trapped and the presence of wMel was recorded. In this spatiotemporal modelling study, we assessed the effect of the release programme on the incidence of dengue and chikungunya. We used spatiotemporally explicit mathematical models applied to geocoded dengue cases (N=283 270) from 2010 to 2019 and chikungunya cases (N=57 705) from 2016 to 2019. Findings On average, 32% of mosquitoes collected from the release zones between 1 month and 29 months after the initial release tested positive for wMel. Reduced wMel introgression occurred in locations and seasonal periods in which cases of dengue and chikungunya were historically high, with a decrease to 25% of mosquitoes testing positive for wMel during months in which disease incidence was at its highest. Despite incomplete introgression, we found that the releases were associated with a 38% (95% CI 32–44) reduction in the incidence of dengue and a 10% (4–16) reduction in the incidence of chikungunya. Interpretation Stable establishment of wMel in the geographically diverse, urban setting of Rio de Janeiro seems to be more complicated than has been observed elsewhere. However, even intermediate levels of wMel seem to reduce the incidence of disease caused by two arboviruses. These findings will help to guide future release programmes. Funding Bill & Melinda Gates Foundation and the European Research Council.
The Involvement of Atlastin in Dengue Virus and Wolbachia Infection in Aedes aegypti and Its Regulation by aae-miR-989
23637M. Hussain, T. Bradshaw, M. Lee and S. Asgari, Microbiology Spectrum, 2022-09-27 06:48:46.
Endoplasmic reticulum (ER)-shaping atlastin proteins (ATLs) have been demonstrated to play a functional role during flavivirus replication in mammalian cells. For dengue virus (DENV), atlastin is required in the formation of the replication organelles and RNA replication, virion assembly, production of the infectious virus particles, and trafficking or directing the association of vesicle packets with furin. Here, we investigated the involvement of atlastin in DENV replication in the mosquito Aedes aegypti and explored the possibility of its manipulation by the endosymbiotic bacterium Wolbachia to interfere with DENV replication. Results showed the expression of Ae. aegypti atlastin gene (AaATL) was upregulated in DENV-infected Aag2 cells, and its silencing led to reduced DENV replication. Contrary to our assumption that AaATL could be downregulated by Wolbachia, we did not find evidence for that in Wolbachia-infected cell lines, but this was the case in mosquitoes. Further, silencing AaATL did not have any effect on Wolbachia density. Our results also suggest that aae-miR-989 miRNA negatively regulates AaATL. The oversupply of the miRNA mimic led to reduced DENV replication consistent with the positive role of AaATL in DENV replication. Overall, the results favor AaATL’s involvement in DENV replication; however, there is no support that the protein is involved in Wolbachia-mediated DENV inhibition. In addition, the results contribute to discerning further possible overlapping functions of ATLs in mosquitoes and mammalian cells.
Analysis of Aedes aegypti microRNAs in response to Wolbachia wAlbB infection and their potential role in mosquito longevity
23564C. Bishop, M. Hussain, L. E. Hugo and S. Asgari, Scientific Reports, 12:15245. 2022-09-09 14:56:37.
The mosquito Aedes aegypti is the primary vector of a range of medically important viruses including dengue, Zika, West Nile, yellow fever, and chikungunya viruses. The endosymbiotic bacterium Wolbachia pipientis wAlbB strain is a promising biocontrol agent for blocking viral transmission by Ae. aegypti. To predict the long-term efficacy of field applications, a thorough understanding of the interactions between symbiont, host, and pathogen is required. Wolbachia influences host physiology in a variety of ways including reproduction, immunity, metabolism, and longevity. MicroRNAs (miRNAs) are highly conserved small non-coding RNAs that regulate gene expression in eukaryotes and viruses. Several miRNAs are known to regulate biological processes in Drosophila and mosquitoes, including facilitating Wolbachia maintenance. We generated the first chromosomal map of Ae. aegypti miRNAs, and compared miRNA expression profiles between a wAlbB-transinfected Ae. aegypti mosquito line and a tetracycline cleared derivative, using deep small RNA-sequencing. We found limited modulation of miRNAs in response to wAlbB infection. Several miRNAs were modulated in response to age, some of which showed greater upregulation in wAlbB-infected mosquitoes than in tetracycline cleared ones. By selectively inhibiting some differentially expressed miRNAs, we identified miR-2946-3p and miR-317-3p as effecting mosquito longevity in Wolbachia-infected mosquitoes.
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.
Modified mosquito releases to fight dengue fever, chikungunya or yellow fever
23555Sewell, Tammy, OICANADIAN, 2022-09-05 14:35:46.
To date, only one technique based on genetically modified mosquitoes has been developed at an operational level, it is the RIDL technique (release of insects carrying a dominant lethal gene, or release of insects carrying a dominant lethality gene). Male mosquitoes which, unlike females, do not bite, are genetically modified. Their offspring die before reaching adulthood. This technique has received authorization from the US Environmental Protection Agency. Last spring, the private company Oxitec began a trial in Florida consisting in disseminating mosquito eggs Aedes aegypti (known to carry many viruses such as dengue fever, yellow fever, chikungunya and Zika) genetically modified in nature for three months.
Call for public consultation ̶ Development of Target Product Profiles (TPPs) for Wolbachia infected Aedes aegypti population replacement intervention
23511World Health Organization, WHO, 2022-08-31 19:42:27.
WHO aims to reduce the global burden of dengue by 25% by 2030. To reach this goal, it is imperative to provide control programmes with sustainable vector control tools. Wolbachia, a symbiotic bacterium that occurs naturally in many insects, has been successfully transferred into the Aedes aegypti mosquito and has been found to reduce the transmission of the dengue virus. Some studies have also shown that this intervention could be sustained for more extended periods. The WHO Vector Control Advisory Group has assessed this intervention and confirmed its public health value for dengue control. WHO has identified a need to develop the Target Product Profiles (TPPs) of current and emerging vector control products to support their optimization. Consequently, a Technical Advisory Group (TAG) was established by WHO to define optimal and minimally acceptable characteristics for developing the TPPs. The TAG is being supported by the WHO secretariat.
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.
A multiplexed, confinable CRISPR/Cas9 gene drive propagates in caged Aedes aegypti populations
23429M. A. E. Anderson, E. Gonzalez, M. P. Edgington, J. X. D. Ang, D.-K. Purusothaman, L. Shackleford, K. Nevard, S. A. N. Verkuijl, T. Harvey-Samuel, P. T. Leftwich, K. Esvelt and L. Alphey, bioRxiv, 2022.08.12.503466. 2022-08-12 07:19:58.
Here, we test the regulatory sequences from the Ae. aegypti benign gonial cell neoplasm (bgcn) homolog to express Cas9 in the germline to find an expression timing more conducive to homing. We also created a separate multiplexing (targeting multiple different sites within the target gene) sgRNA-expressing homing cassette inserted into the Ae. aegypti kynurenine 3-monooxygenase (kmo) gene to limit the consequences of resistance alleles. This creates a ‘split’ gene drive such that one part does not drive, allowing control over geographic spread and temporal persistence. When combined, these two elements provide highly effective germline cutting at the kmo locus and act as a gene drive. Our target genetic element was driven through a cage trial population such that carrier frequency of the element increased from 50% to up to 89% of the population despite significant fitness costs to kmo insertions. Deep sequencing suggests that the multiplexing design could mitigate resistance allele formation in our gene drive system.Significance statement Mosquito-borne diseases affect millions of people worldwide, with the yellow fever mosquito (Aedes aegypti) being the principal vector of many viral diseases. Effective measures for controlling this mosquito are sorely needed. Gene drive systems have arisen as a potential tool for mosquito control due to their ability of biasing inheritance of a trait into a target population. Here, we assess a split gene drive, based on CRISPR/Cas9 endonuclease technology driving a target element into the mosquito population. Evaluated over successive generations in a replicated cage trial, the drive successfully biased its inheritance, increasing in frequency from 50% to up to 89%. Our results are encouraging for the potential use of this type of contained gene drive system for mosquito control in endemic areas.Competing Interest StatementThe authors have declared no competing interest.
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.
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.
Wolbachia Dynamics in Mosquitoes with Incomplete CI and Imperfect Maternal Transmission by a DDE System
23393Y. Su, B. Zheng and X. Zou, Bulletin of Mathematical Biology, 84:95. 2022-08-01 08:09:11.
In this paper, we propose a delay differential equation model to describe the Wolbachia infection dynamics in mosquitoes in which the key factor of cytoplasmic incompactibility (CI) is incorporated in a more natural way than those in the literature. By analyzing the dynamics of the model, we are able to obtain some information on the impact of four important parameters: the competition capabilities of the wild mosquitoes and infected mosquitoes, the maternal transmission level and the CI level. The analytic results show that there are ranges of parameters that support competition exclusion principle, and there are also ranges of parameters that allow co-persistence for both wild and infected mosquitoes. These ranges account for the scenarios of failure of invasion, invasion and suppressing the wild mosquitoes, and invasion and replacing the wild mosquitoes. We also discuss some possible future problems both in mathematics and in modeling.
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.
Wolbachia wPip Blocks Zika Virus Transovarial Transmission in Aedes albopictus
23333Y. Guo, J. Guo, Y. Li, X. Zheng and Y. Wu, Microbiol Spectrum, e0263321. 2022-07-27 08:36:55.
Area-wide application of Wolbachia to suppress mosquito populations and their transmitted viruses has achieved success in multiple countries. However, the mass release of Wolbachia-infected male mosquitoes involves a potential risk of accidentally releasing fertile females. In this study, we employed ovarian cells of the Ae. albopictus GUA, HC, and GT lines, which exhibit key traits, and compared them to better understand how Wolbachia inhibits ZIKV transovarial transmission. Our results showed an almost complete blockade of ZIKV transmission in HC female mosquitoes. Wolbachia in natively infected GUA mosquitoes negative affected ZIKV, and this interference was shown by slightly lower loads than those in HC mosquitoes. Overall, our work helps show how Wolbachia blocks ZIKV expansion and maintenance in the ovaries of Ae. albopictus and aids in understanding Wolbachia-ZIKV interactions in mosquitoes.
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.
Attempts to use breeding approaches in Aedes aegypti to create lines with distinct and stable relative Wolbachia densities
23279A. J. Mejia, L. Jimenez, H. L. C. Dutra, R. Perera and E. A. McGraw, Heredity, 2022-07-22 10:12:25.
Wolbachia is an insect endosymbiont being used for biological control in the mosquito Aedes aegypti because it causes cytoplasmic incompatibility (CI) and limits viral replication of dengue, chikungunya, and Zika viruses. While the genetic mechanism of pathogen blocking (PB) is not fully understood, the strength of both CI and PB are positively correlated with Wolbachia densities in the host. Wolbachia densities are determined by a combination of Wolbachia strain and insect genotype, as well as interactions with the environment. We employed both artificial selection and inbreeding with the goal of creating lines of Ae. aegypti with heritable and distinct Wolbachia densities so that we might better dissect the mechanism underlying PB. We were unable to shift the mean relative Wolbachia density in Ae. aegypti lines by either strategy, with relative densities instead tending to cycle over a narrow range. In lieu of this, we used Wolbachia densities in mosquito legs as predictors of relative densities in the remaining individual’s carcass. Because we worked with outbred mosquitoes, our findings indicate either a lack of genetic variation in the mosquito for controlling relative density, natural selection against extreme densities, or a predominance of environmental factors affecting densities. Our study reveals that there are moderating forces acting on relative Wolbachia densities that may help to stabilize density phenotypes post field release. We also show a means to accurately bin vector carcasses into high and low categories for non-DNA omics-based studies of Wolbachia-mediated traits.
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.
CRISPR-Mediated Genome Engineering in Aedes aegypti
23209R. Sun, M. Li, C. J. McMeniman and O. S. Akbari, piRNA: Methods and Protocols, 2022-07-01 06:21:38.
CRISPR-mediated genome engineering technologies have been adapted to a wide variety of organisms with high efficiency and specificity. The yellow fever mosquito, Aedes aegyptiAedes aegypti, is one such organism. It is also responsible for transmitting a wide variety of deadly viruses including Dengue, Zika, Yellow fever, and Chikungunya. The key to successful CRISPR-mediated gene editingGene editing applications is the delivery of both Cas9 ribonuclease and single-guide RNA (sgRNASingle guide RNA (sgRNA)) to the nucleus of desired cells. Various methods have been developed for supplying the Cas9 endonuclease, sgRNASingle guide RNA (sgRNA), and donor DNA to Ae. aegypti. In this chapter, we focus on methods of direct embryoEmbryosdelivery of editing components, presenting detailed step-by-step CRISPR/Cas9-based genome-editing protocols for inducing desired heritable edits in mosquitoes as well as insights into successful application of these protocols. We also highlight potential opportunities for customizing these protocols to manipulate the mosquito genome for innovative in vivoIn vivo gene function studies.
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.
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.
Sensitivity of wMel and wAlbB Wolbachia infections in Aedes aegypti Puducherry (Indian) strains to heat stress during larval development
23056K. Gunasekaran, C. Sadanandane, D. Panneer, A. Kumar, M. Rahi, S. Dinesh, B. Vijayakumar, M. Krishnaraja, S. K. Subbarao and P. Jambulingam, Parasites and Vectors, 15:221. 2022-06-21 15:19:54.
BACKGROUND: ICMR-Vector Control Research Centre, Puducherry, India, developed two colonies of Aedes aegypti infected with wMel and wAlbB Wolbacia strains called Ae. aegypti (Pud) lines for dengue control. The sensitivity of wMel and wAlbB strains in Ae. aegypti (Pud) lines to heat stress was studied. METHODS: wMel and wAlbB infected and uninfected Ae. aegypti larvae (first to fourth instars) were reared in the laboratory to adults at 26 °C, 30 °C, 36 °C and 40 °C constant temperatures and also 26-30 °C, 26-36 °C and 26-40 °C diurnal cyclic temperatures. The adults were tested for Wolbachia infection. Experiments were also carried out rearing the larvae under simulated field conditions in summer (April and June) under sunlight using fully open and half open bowls and also under sunlight and natural shade. RESULTS: At 36 °C and 40 °C constant temperatures, complete larval mortality was observed. At 30 °C and 26 °C, no larval mortality occurred, but Wolbachia density was relatively low in wMel infected males compared to control (maintained at 26 ± 1 °C). At diurnal cyclic temperature of 26-40 °C, Wolbachia density was reduced in males of both the (Pud) lines, but not in females. At 26-36 °C, reduction in Wolbachia density was observed in wMel males but not in wAlbB males. At 26-30 °C, no significant reduction in Wolbachia density was observed with wMel and wAlbB strains. In simulated field conditions (April), under sunlight, the daytime water temperature reached a maximum of 35.7 °C in both full and half open bowls. No larval mortality occurred. Wolbachia frequency and density was reduced in wMel-infected Ae. aegypti (Pud) males from both type of bowls and in females from full open bowls, and in wAlbB males from half open bowls. In June, rearing of larvae under sunlight, the first-instar larvae experienced a maximum daytime water temperature of > 38 °C that caused complete mortality. No larval mortality was observed in bowls kept under shade (< 32 °C). CONCLUSIONS: Exposure of larvae to higher rearing temperatures in the laboratory and simulated-field conditions reduced the densities of wMel and wAlbB strains particularly in males, but the impact was more pronounced for wMel strain. The actual effect of heat stress on the stability of these two Wolbachia strains needs to be tested under natural field conditions.
Current Status of Mosquito Handling, Transporting and Releasing in Frame of the Sterile Insect Technique
22868J. Guo, X. Zheng, D. Zhang and Y. Wu, Insects, 13. 2022-06-10 07:44:12.
The sterile insect technique (SIT) and its related technologies are considered to be a powerful weapon for fighting against mosquitoes. As an important part of the area-wide integrated pest management (AW-IPM) programs, SIT can help reduce the use of chemical pesticides for mosquito control, and consequently, the occurrence of insecticide resistance. The mosquito SIT involves several important steps, including mass rearing, sex separation, irradiation, packing, transportation, release and monitoring. To enable the application of SIT against mosquitoes to reduce vector populations, the Joint Food and Agriculture Organization of the United Nations (FAO) and the International Atomic Energy Agency (IAEA) Centre (previously called Division) of Nuclear Techniques in Food and Agriculture (hereinafter called Joint FAO/IAEA Centre) and its Insects Pest Control sub-program promoted a coordinated research project (CRP) entitled “Mosquito handling, transport, release and male trapping methods” to enhance the success of SIT. This article summarizes the existing explorations that are critical to the handling and transporting of male mosquitoes, offers an overview of detailed steps in SIT and discusses new emerging methods for mosquito releases, covering most processes of SIT.
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.
Reply to: Assessing the efficiency of Verily’s automated process for production and release of male Wolbachia-infected mosquitoes
22643J. E. Crawford, K. C. Hopkins, A. Buchman, T. Zha, P. Howell, E. Kakani, J. R. Ohm, N. Snoad, L. Upson, J. Holeman, P. Massaro, S. L. Dobson, F. S. Mulligan and B. J. White, Nature Biotechnology, 2022-05-26 06:34:15.
We appreciate the comments from Bouyer et al. under their mandate as a United Nations agency program (‘to promote the safe and appropriate use of nuclear techniques and related technologies in food and agriculture’) on our paper1 . The centuries-old fight against mosquito-borne disease has entered a new phase that is both exciting and fast-moving. Many promising technologies and techniques have been developed in the past 2 decades, including mosquito colonies stably infected with Wolbachia2 mosquitoes3,4, a CRISPR–Cas9-based gene drive5 nations of these techniques with older approaches (that is, irradiated Wolbachia releases6,7 , genetically modified sterile and even combi). In a world where more than half of all humans are at risk of contracting mosquito-borne diseases across a range of economic and geographic landscapes, we think that an array of tools will be needed to turn the tide against the massive public health burden of these diseases.
Assessing the efficiency of Verily’s automated process for production and release of male Wolbachia-infected mosquitoes
22641J. Bouyer, H. Maiga and M. J. B. Vreysen, Nature Biotechnology, 2022-05-26 06:27:58.
A paper by Crawford et al.1 titled ‘Efficient production of male Wolbachia-infected Aedes aegypti mosquitoes enables large-scale suppression of wild populations’ reports a mosquito control suppression trial carried out from2017 to 2018 in Fresco Country, California, USA1 . Between 7.5 million and 14.4 million Wolbachia-infected male mosquitoes were released during the study, which achieved suppression rates of 69% and 95%, respectively. Although the work provided important insights for future Aedes genetic control programs—particularly the information on the immigration of fertile females into release areas—the paper contains several omissions and errors. Below, we discuss how these relate to three main areas: regulatory oversight, entomological efficiency and, finally, cost efficiency.
Elimination of a closed population of the yellow fever mosquito, Aedes aegypti, through releases of self-limiting male mosquitoes
22519P. B. Patil, S. K. Dasgupta, K. Gorman, A. Pickl-Herk, M. Puinean, A. McKemey, B. Char, U. B. Zehr and S. R. Barwale, PLOS Neglected Tropical Diseases, 16:e0010315. 2022-05-16 09:19:04.
Author summary Aedes aegypti L. species is the primary vector responsible for transmission of the dengue virus worldwide including chikungunya, yellow fever and Zika virus. The experiment presented in the manuscript represents a study undertaken to demonstrate suppression of the wild type Ae. aegypti population in large outdoor field cages with natural exposure to the environment (physically-contained field cage facility) by sustained releases of male adults of OX513A Ae. aegypti strain. This investigation is a phase-2 contained study as per the World Health Organization guidelines for evaluation of genetically modified organisms and was recommended by the Indian regulatory board. This experiment demonstrates suppression of wild type Ae. aegypti population by sustained releases of OX513A male adults in a contained facility. The prospect of the project is to demonstrate and implement the technology for controlling/suppression of the Ae. aegypti vector in the open field environment.
Simple, sensitive, and cost-effective detection of wAlbB Wolbachia in Aedes mosquitoes, using loop mediated isothermal amplification combined with the electrochemical biosensing method
22480P. Thayanukul, B. Lertanantawong, W. Sirawaraporn, S. Charasmongkolcharoen, T. Chaibun, R. Jittungdee and P. Kittayapong, PLOS Neglected Tropical Diseases, 16:e0009600. 2022-05-13 07:05:35.
Author summary Mosquito-borne diseases such as dengue, chikungunya, zika, and yellow fever are transmitted to humans mainly by the bites of Aedes aegypti mosquitoes. Controlling the vectors of these diseases relies mostly on the use of insecticides. However, the efficiency has been reduced through the development of insecticide resistance in mosquitoes. Wolbachia is an endosymbiotic bacterium that is naturally found in 40% of insects, including mosquitoes. The bacterium can protect its insect hosts from viral infections and can also cause sterility in insect host populations, therefore, providing an opportunity to use it for human disease control. Application of a Wolbachia trans-infected mosquitoes needs simple, rapid and sensitive methods for detecting the bacteria in released mosquitoes. In this paper, we develop the methods of LAMP and BIOSENSORS for detecting wAlbB Wolbachia in mosquitoes. Our positive LAMP reaction can be visualized by color change from violet to blue at a sensitivity of ≥ 10 pg of genomic DNA. When used in combination with the BIOSENSOR method, the sensitivity increases a millionfold without losing specificity. Our study suggests that both developed methods, either used in combination or stand-alone, are efficient and cost-effective, hence, they could be applied for routine surveys of Wolbachia in mosquito control programs that use Wolbachia-based approaches.
Self-Deleting Genes Could Control Mosquitoes And Prevent Vector-Borne Diseases
22493A. Russell, Texas AM TODAY, 2022-05-11 07:33:02.
Texas A&M AgriLife Research scientists are testing a technology to make temporary genetic modifications in mosquitoes that self-delete over time. The mechanism to make temporary genetic changes could be important for scientists hoping to modify mosquitoes in ways that help manage populations and prevent vector-borne diseases like West Nile virus without permanently altering wild populations’ genetic makeup. An article detailing their test results is published in Proceedings of the National Academy of Sciences’ PNAS Nexus. The authors, Zach Adelman and Kevin Myles, both professors in the Texas A&M University College of Agriculture and Life Sciences Department of Entomology, describe a method for programming the removal of edited genes within populations of mosquitoes over multiple generations. The method is a first step toward building safeguards for genetic modifications developed to control populations of mosquitoes and the vector-borne diseases they carry. The idea is to test proposed changes without making the changes permanent and without the risk of transmitting them to wild populations, Adelman said.
Mosquitoes Genetically Modified to Stop Disease Pass Early Test
22448L. Rapaport, WebMD, 2022-05-09 08:57:53.
Genetically modified mosquitoes released in the U.S. appear to have passed an early test that suggests they might one day help reduce the population of insects that transmit infectious diseases. As part of the test, scientists released nearly 5 million genetically engineered male Aedes aegypti mosquitoes over the course of 7 months in the Florida Keys. Male mosquitoes don’t bite people, and these were also modified so they would transmit a gene to female offspring that causes them to die before they can reproduce. In theory, this means the population of Aedes aegypti mosquitoes would die off over time, so they wouldn’t spread diseases any more. The goal of this pilot project in Florida was to see if these genetically modified male mosquitoes could successfully mate with females in the wild, and to confirm whether their female offspring would indeed die before they could reproduce. On both counts, the experiment was a success, Oxitec, the biotechnology company developing these engineered Aedes aegypti mosquitoes, said in a webina
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.
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.”
Transient Introgression of Wolbachia into Aedes aegypti Populations Does Not Elicit an Antibody Response to Wolbachia Surface Protein in Community Members
22655E. Lee, T. Hien Nguyen, T. Yen Nguyen, S. Nam Vu, N. Duong Tran, L. Trung Nghia, Q. Mai Vien, T. Dong Nguyen, R. Kriiger Loterio, I. Iturbe-Ormaetxe, H. A. Flores, S. L. O'Neill, D. Anh Dang, C. P. Simmons and J. E. Fraser, Pathogens, 11. 2022-05-03 06:41:58.
Wolbachia is an endosymbiotic bacterium that can restrict the transmission of human pathogenic viruses by Aedes aegypti mosquitoes. Recent field trials have shown that dengue incidence is significantly reduced when Wolbachia is introgressed into the local Ae. aegypti population. Female Ae. aegypti are anautogenous and feed on human blood to produce viable eggs. Herein, we tested whether people who reside on Tri Nguyen Island (TNI), Vietnam developed antibodies to Wolbachia Surface Protein (WSP) following release of Wolbachia-infected Ae. aegypti, as a measure of exposure to Wolbachia. Paired blood samples were collected from 105 participants before and after mosquito releases and anti-WSP titres were measured by ELISA. We determined no change in anti-WSP titres after ~30 weeks of high levels of Wolbachia-Ae. aegypti on TNI. These data suggest that humans are not exposed to the major Wolbachia surface antigen, WSP, following introgression of Wolbachia-infected Ae. aegypti mosquitoes.
International shipments of Wolbachia-infected mosquito eggs: towards the scaling-up of World Mosquito Program operations
23390J. A. Denton, D. A. Joubert, A. A. Goundar and J. R. L. Gilles, Scientific and Technical Review, 41:91-99. 2022-05-01 08:01:14.
The Wolbachia insect control method, employed by the World Mosquito Program (WMP), relies on introgressing Wolbachia through target Aedes aegypti populations to reduce the incidence of dengue. Since 2010, the WMP has been producing Wolbachia-infected mosquitoes at numerous sites across the globe for release in 11 countries. As the technology has matured, greater focus has been placed on mosquito production at larger central facilities for transport to remote release sites, both domestically and internationally. Of particular note is the production of Wolbachia-infected mosquitoes at the WMP's Australian production facility for successful international deployments in Fiji, Vanuatu, Kiribati and Sri Lanka. This requires careful management of both production and supply-chain processes to ensure that the quality of the mosquito eggs, specifically the hatch rate and Wolbachia infection rate, is maintained. To ensure the cost-effectiveness and scalability of the Wolbachia method, these processes will be further refined to facilitate deployment from large centralised production facilities.
Engineering a self-eliminating transgene in the yellow fever mosquito, Aedes aegypti
21920K. Chae, C. Dawson, C. Valentin, B. Contreras, J. Zapletal, K. M. Myles and Z. N. Adelman, PNAS Nexus, 2022-04-28 08:54:37.
Promising genetics-based approaches are being developed to reduce or prevent the transmission of mosquito-vectored diseases. Less clear is how such transgenes can be removed from the environment, a concern that is particularly relevant for highly invasive gene drive transgenes. Here, we lay the groundwork for a transgene removal system based on single-strand annealing (SSA), a eukaryotic DNA repair mechanism. An SSA-based rescuer strain (kmoRG) was engineered to have direct repeat sequences (DRs) in the Ae. aegypti kynurenine 3-monooxygenase (kmo) gene flanking the intervening transgenic cargo genes, DsRED and EGFP. Targeted induction of DNA double-strand breaks (DSBs) in the DsRED transgene successfully triggered complete elimination of the entire cargo from the kmoRG strain, restoring the wild-type kmo gene and thereby normal eye pigmentation. Our work establishes the framework for strategies to remove transgene sequences during the evaluation and testing of modified strains for genetics-based mosquito control.
Self-eliminating genes tested on mosquitoes
21924A. Russell, AGRILIFE Today, 2022-04-27 09:13:46.
Texas A&M AgriLife Research scientists have tested a technology to make temporary genetic modifications in mosquitoes. The modifications self-delete over time. Texas A&M AgriLife Research scientists published an article detailing a mechanism to make temporary genetic alterations to mosquitoes. The mechanism to make temporary genetic changes could be important for scientists hoping to modify mosquitoes in ways that help manage populations and prevent vector-borne diseases like West Nile virus without permanently altering wild populations’ genetic makeup.
Pilot trial using mass field-releases of sterile males produced with the incompatible and sterile insect techniques as part of integrated Aedes aegypti control in Mexico
22224A. Martín-Park, A. Che-Mendoza, Y. Contreras-Perera, S. Pérez-Carrillo, H. Puerta-Guardo, J. Villegas-Chim, G. Guillermo-May, A. Medina-Barreiro, H. Delfín-González, R. Méndez-Vales, S. Vázquez-Narvaez, J. Palacio-Vargas, F. Correa-Morales, G. Ayora-Tal, PLoS Negl Trop Dis, 16:e0010324. 2022-04-26 15:46:43.
We implemented a controlled before-and-after quasi-experimental study in two suburban localities of Yucatan (Mexico): San Pedro Chimay (SPC), which received IIT-SIT, and San Antonio Tahdzibichén used as control. Release of wAlbB Ae. aegypti males at SPC extended for 6 months (July-December 2019), covering the period of higher Ae. aegypti abundance. Entomological indicators included egg hatching rates and outdoor/indoor adult females collected at the release and control sites. Approximately 1,270,000 lab-produced wAlbB-infected Ae. aegypti males were released in the 50-ha treatment area (2,000 wAlbB Ae. aegypti males per hectare twice a week in two different release days, totaling 200,000 male mosquitoes per week). The efficacy of IIT-SIT in suppressing indoor female Ae. aegypti density (quantified from a generalized linear mixed model showing a statistically significant reduction in treatment versus control areas) was 90.9% a month after initiation of the suppression phase, 47.7% two months after (when number of released males was reduced in 50% to match local abundance), 61.4% four months after (when initial number of released males was re-established), 88.4% five months after and 89.4% at six months after the initiation of the suppression phase. A proportional, but lower, reduction in outdoor female Ae. aegypti was also quantified (range, 50.0-75.2% suppression). CONCLUSIONS/SIGNIFICANCE: Our study, the first open-field pilot implementation of Wolbachia IIT-SIT in Mexico and Latin-America, confirms that inundative male releases can significantly reduce natural populations of Ae. aegypti. More importantly, we present successful pilot results of the integration of Wolbachia IIT-SIT within a IVM plan implemented by Ministry of Health personnel.
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.
Aedes aegypti abundance and insecticide resistance profiles in the applying Wolbachia to eliminate dengue trial
21790W. Tantowijoyo, S. K. Tanamas, I. Nurhayati, S. Setyawan, N. Budiwati, I. Fitriana, I. Ernesia, D. S. Wardana, E. Supriyati, E. Arguni, Y. Meitika, E. Prabowo, B. Andari, B. R. Green, L. Hodgson, E. Rancès, P. A. Ryan, S. L. O'Neill, K. L. Anders, M. R. A, PLOS Neglected Tropical Diseases, 16:e0010284. 2022-04-20 07:01:27.
The Applying Wolbachia to Eliminate Dengue (AWED) trial was a parallel cluster randomised trial that demonstrated Wolbachia (wMel) introgression into Ae. aegypti populations reduced dengue incidence. In this predefined substudy, we compared between treatment arms, the relative abundance of Ae. aegypti and Ae. albopictus before, during and after wMel-introgression. Between March 2015 and March 2020, 60,084 BG trap collections yielded 478,254 Ae. aegypti and 17,623 Ae. albopictus. Between treatment arms there was no measurable difference in Ae. aegypti relative abundance before or after wMel-deployments, with a count ratio of 0.96 (95% CI 0.76, 1.21) and 1.00 (95% CI 0.85, 1.17) respectively. More Ae. aegypti were caught per trap per week in the wMel-intervention arm compared to the control arm during wMel deployments (count ratio 1.23 (95% CI 1.03, 1.46)). Between treatment arms there was no measurable difference in the Ae. albopictus population size before, during or after wMel-deployment (overall count ratio 1.10 (95% CI 0.89, 1.35)). We also compared insecticide resistance phenotypes of Ae. aegypti in the first and second years after wMel-deployments. Ae. aegypti field populations from wMel-treated and untreated arms were similarly resistant to malathion (0.8%), permethrin (1.25%) and cyfluthrin (0.15%) in year 1 and year 2 of the trial. In summary, we found no between-arm differences in the relative abundance of Ae. aegypti or Ae. albopictus prior to or after wMel introgression, and no between-arm difference in Ae. aegypti insecticide resistance phenotypes. These data suggest neither Aedes abundance, nor insecticide resistance, confounded the epidemiological outcomes of the AWED trial.
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.”
A metapopulation approach to identify targets for Wolbachia-based dengue control
22221A. Reyna-Lara, D. Soriano-Paños, J. H. Arias-Castro, H. J. Martínez and J. Gómez-Gardeñes, Chaos, 32:041105. 2022-04-18 15:42:29.
Over the last decade, the release of Wolbachia-infected Aedes aegypti into the natural habitat of this mosquito species has become the most sustainable and long-lasting technique to prevent and control vector-borne diseases, such as dengue, zika, or chikungunya. However, the limited resources to generate such mosquitoes and their effective distribution in large areas dominated by the Aedes aegypti vector represent a challenge for policymakers. Here, we introduce a mathematical framework for the spread of dengue in which competition between wild and Wolbachia-infected mosquitoes, the cross-contagion patterns between humans and vectors, the heterogeneous distribution of the human population in different areas, and the mobility flows between them are combined. Our framework allows us to identify the most effective areas for the release of Wolbachia-infected mosquitoes to achieve a large decrease in the global dengue prevalence.
Environmental factors influence the local establishment of Wolbachia in Aedes aegypti mosquitoes in two small communities in central Vietnam [version 2]
21728N. T. Hien, D. D. Anh, N. H. Le, N. T. Yen, T. V. Phong, V. S. Nam, T. N. Duong, N. B. Nguyen, D. T. T. Huong, L. Q. Hung, C. N. T. Trinh, N. V. Hoang, V. Q. Mai, L. T. Nghia, N. T. Dong, L. H. Tho, S. Kutcher, T. P. Hurst, J. L. Montgomery, M. Woolfit, E, Gates Open Research, 5:147. 2022-04-18 09:54:42.
Background: The wMel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown to reduce transmission of dengue and other pathogens, under both laboratory and field conditions. Here we describe the entomological outcomes of wMel Wolbachia mosquito releases in two small communities in Nha Trang City in central Vietnam. Methods: The wMel strain of Wolbachia was backcrossed into local Aedes aegypti genotype and mosquito releases were undertaken by community members or by staff. Field monitoring was undertaken to track Wolbachia establishment in local Ae. aegypti mosquito populations. Ecological studies were undertaken to assess relationships between environmental factors and the spatial and temporal variability in Wolbachia infection prevalence in mosquitoes. Results: Releases of wMel Wolbachia Ae. aegypti mosquitoes in two small communities in Nha Trang City resulted in the initial establishment of Wolbachia in the local Ae. aegypti mosquitopopulations, followed by seasonal fluctuations in Wolbachia prevalence. There was significant small-scale spatial heterogeneity in Wolbachia infection prevalence in the Tri Nguyen Village site, resulting in the loss of wMel Wolbachia infection in mosquitoes in north and center areas, despite Wolbachia prevalence remaining high in mosquitoes in the south area. In the second site, Vinh Luong Ward, Wolbachia has persisted at a high level in mosquitoes throughout this site despite similar seasonal fluctuations in wMel Wolbachia prevalence. Conclusion: Seasonal variation in Wolbachia infection prevalence in mosquitoes was associated with elevated temperature conditions, and was possibly due to imperfect maternal transmission of Wolbachia. Heterogeneity in Wolbachia infection prevalence was found throughout one site, and indicates additional factors may influence Wolbachia establishment.
Potential Adverse Effects of GE Mosquitoes Unknown
21773B. Giuffre, The Epoch Times, 2022-04-17 08:04:34.
“Safe and sustainable.” That’s what Oxitec, a British biological pest control company, calls its genetically modified (GM) or genetically engineered (GE) mosquito pesticide product. The company claims its product is nontoxic to humans and animals and won’t harm beneficial insects such as bees and butterflies. The experiment’s goal is to test the use of GE mosquitoes for reducing the transmission of diseases such as dengue, Zika, chikungunya, and yellow fever. The method of action is post-CRISPR, but uses similar gene engineering technology—inserting a double whammy into the Aedes aegypti male mosquito: a lethal gene and a fluorescent gene (for tracking). “The goal here is not to kill mosquitoes,” said epidemiologist Thomas Scott of the GE mosquito projects in Science magazine, “It’s to prevent people from getting infected and sick and dying.”
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.
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
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.
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.
Genetic Stability and Fitness of Aedes aegypti Red-Eye Genetic Sexing Strains With Pakistani Genomic Background for Sterile Insect Technique Applications
22452M. Misbah-ul-Haq, D. O. Carvalho, L. D. de la Fuente, A. A. Augustinos and K. Bourtzis, Frontiers in Bioengineering and Biotechnology, 10. 2022-03-31 09:37:56.
The mosquito species Aedes aegypti is the primary transmitter of viruses that cause endemic diseases like dengue in Pakistan. It is also a cause of other vector-borne diseases like yellow fever, Zika fever, and chikungunya, which significantly impact human health worldwide. In the absence of efficient vaccines (except for yellow fever) or drugs, vector control methods, such as the sterile insect technique (SIT), have been proposed as additional tools for the management of these diseases. Mosquito SIT programs are based on the release of sterile males and it is important female releases to be ideally zero or to be kept at a minimum, since females are the ones that bite, blood-feed and transmit pathogens. Recently, an Ae. aegypti genetic sexing strain (GSS), with and without a recombination-suppressing inversion (Inv35), was developed using the eye color as a selectable marker, with males having black eyes and females red eyes. In the present study, we introgressed the sexing features and the Inv35 of the Ae. aegypti red-eye GSS into the Pakistani genomic background aiming to their future use for SIT applications in the country. Both introgressed strains, the Red-eye GSS-PAK and the Red-eye GSS/Inv35-PAK, were evaluated in respect to their genetic stability and biological quality by assessing parameters like recombination rate, fecundity, fertility, pupal and adult recovery, time of development, pupal weight, survival, and flight ability in comparison with a wild Pakistani population (PAK). The results suggest that the sexing features and the recombination suppression properties of Inv35 were not affected after their introgression into the local genomic background; however, some biological traits of the two newly constructed strains were affected, positively or negatively, suggesting that a thorough quality control analysis should be performed after the introgression of a GSS into a new genomic background prior to its use in SIT field trials or applications. The importance of using GSS with local genomic background for SIT applications against Aedes aegypti is also discussed.
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.”
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.
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.
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.
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.
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.
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.
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.
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.
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.
Wolbachia in Aedes koreicus: Rare Detections and Possible Implications
20475C. Damiani, A. Cappelli, F. Comandatore, F. Montarsi, A. Serrao, A. Michelutti, M. Bertola, M. V. Mancini, I. Ricci, C. Bandi and G. Favia, Insects, 13. 2022-02-21 08:21:51.
The emerging distribution of new alien mosquito species was recently described in Europe. In addition to the invasion of Aedes albopictus, several studies have focused on monitoring and controlling other invasive Aedes species, as Aedes koreicus and Aedes japonicus. Considering the increasing development of insecticide resistance in Aedes mosquitoes, new control strategies, including the use of bacterial host symbionts, are proposed. However, little is known about the bacterial communities associated with these species, thus the identification of possible candidates for Symbiotic Control is currently limited. The characterization of the natural microbiota of field-collected Ae. koreicus mosquitoes from North-East Italy through PCR screening, identified native infections of Wolbachia in this species that is also largely colonized by Asaia bacteria. Since Asaia and Wolbachia are proposed as novel tools for Symbiotic Control, our study supports their use for innovative control strategies against new invasive species. Although the presence of Asaia was previously characterized in Ae. koreicus, our study characterized this Wolbachia strain, also inferring its phylogenetic position. The co-presence of Wolbachia and Asaia may provide additional information about microbial competition in mosquito, and to select suitable phenotypes for the suppression of pathogen transmission and for the manipulation of host reproduction in Ae. koreicus.
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.
Adult mosquito predation and potential impact on the sterile insect technique
21014N. S. Bimbilé Somda, H. Maïga, W. Mamai, T. Bakhoum, T. Wallner, S. B. Poda, H. Yamada and J. Bouyer, Scientific Reports, 12:2561. 2022-02-15 06:32:02.
The sterile insect technique is a promising environmentally friendly method for mosquito control. This technique involves releasing laboratory-produced sterile males into a target field site, and its effectiveness may be affected by the extent of adult mosquito predation. Sterile males undergo several treatments. Therefore, it is vital to understand which treatments are essential in minimizing risks to predation once released. The present study investigates the predation propensity of four mantis species (Phyllocrania paradoxa, Hymenopus coronatus, Blepharopsis mendica, Deroplatys desiccata) and two gecko species (Phelsuma standingi, P. laticauda) on adult Aedes aegypti, Ae. albopictus and Anopheles arabiensis mosquitoes in a laboratory setting. First, any inherent predation preferences regarding mosquito species and sex were evaluated. Subsequently, the effects of chilling, marking, and irradiation, on predation rates were assessed. The selected predators effectively preyed on all mosquito species regardless of the treatment. Predation propensity varied over days for the same individuals and between predator individuals. Overall, there was no impact of laboratory treatments of sterile males on the relative risk of predation by the test predators, unless purposely exposed to double the required sterilizing irradiation dose. Further investigations on standardized predation trials may lead to additional quality control tools for irradiated mosquitoes.
Quality Control Methods for Aedes albopictus Sterile Male Transportation
20392G. D. Mastronikolos, A. Kapranas, G. K. Balatsos, C. Ioannou, D. P. Papachristos, P. G. Milonas, A. Puggioli, I. Pajović, D. Petrić, R. Bellini, A. Michaelakis and N. T. Papadopoulos, Insects, 2022-02-09 09:27:23.
Genetic based mosquito control methods have been gaining ground in recent years for their potential to achieve effective suppression or replacement of vector populations without hampering environments or causing any public health risk. These methods require the mass rearing of the target species in large facilities sized to produce millions of sterile males, as already well established for a number of insects of agricultural importance. Assessing the performance of released males in Sterile Insect Technique (SIT) control programs is of the utmost importance for the success of the operation. Besides the negative effects of mass rearing and sterilization, the handling of sterilized insects and shipment to distant areas may also negatively impact the quality of sterilized males. The aim of the current study was to design and executive quality control (QC) tests for sterilized Aedes albopictus (Asian tiger mosquito) males delivered by air shipment from the mass production facility located in Italy to Greece and Montenegro field release sites. Mass reared mosquito strains were based on biological materials received from Italy, Greece and Montenegro. Tests conducted at the mass rearing facility before transportation revealed a rather high residual female contamination following mechanical sex separation (approximately 1.5% females, regardless of the mosquito strain). Irradiated males of all three mosquito strains induced high levels of sterility to females. Shipment lasting approximately 24 h resulted in approximately 15% mortality, while when shipment lasted nearly two days this increased to almost 40%. The flight ability of sterilized males following one day transportation time was satisfactory (over 60%). The response of sterile males to food and water starvation was comparable and slightly lower than that of wild non-transported males. Longevity of sterile males was shorter than that of wild counterparts and it seems it was not affected by mating to wild females. Both mating propensity and mating competitiveness for wild virgin females was higher for the wild, control males compared to the sterile, transported ones. Overall, the performance of sterile male Ae. albopictus delivered from the mass rearing facility of Italy to Greece in approximately 24 h was satisfactory. Transportation lasting two days or longer incurred detrimental effects on males, which called into question the outcome of the SIT release programs. In conclusion, our results demonstrate the need of quality control procedures, especially when sterile male production facilities are not near to the releasing point. Transportation could be a serious drawback for the implementation of Sterile Insect Releases and, consequently, it is important to establish an efficient and fast transportation of sterilized males in advance.
Assessing Aedes aegypti candidate genes during viral infection and Wolbachia-mediated pathogen blocking
20315L. T. Sigle, M. Jones, M. Novelo, S. A. Ford, N. Urakova, K. Lymperopoulos, R. T. Sayre, Z. Xi, J. L. Rasgon and E. A. McGraw, Insect Molecular Biology, 2022-02-03 09:03:09.
Abstract One approach to control dengue virus transmission is the symbiont Wolbachia, that limits viral infection in mosquitoes. Despite plans for its widespread use in Aedes aegypti, Wolbachia's mode of action remains poorly understood. Many studies suggest that the mechanism is likely multifaceted, involving aspects of immunity, cellular stress, and nutritional competition. A previous study from our group used artificial selection to identify a new mosquito candidate gene related to viral blocking; alpha-mannosidase-2a (alpha-Mann-2a) with a predicted role in protein glycosylation. Protein glycosylation pathways tend to be involved in complex host-viral interactions; however, the function of alpha-mannosidases has not been described in mosquito-virus interactions. We examined alpha-Mann-2a expression in response to virus and Wolbachia infections and whether reduced gene expression, caused by RNA interference (RNAi), affected viral loads. We show that dengue virus (DENV) infection affects the expression of alpha-Mann-2a in a tissue- and time-dependent manner, whereas Wolbachia infection had no effect. In the midgut, DENV prevalence increased following knockdown of alpha-Mann-2a expression in Wolbachia-free mosquitoes, suggesting that alpha-Mann-2a interferes with infection. Expression knockdown had the same effect on the togavirus chikungunya virus (CHIKV), indicating that alpha-Mann-2a may have broad antivirus effects in the midgut. Interestingly, we were unable to knockdown the expression in Wolbachia-infected mosquitoes. We also provide evidence that alpha-Mann-2a may affect the transcriptional level of another gene predicted to be involved in viral blocking and cell adhesion; cadherin87a. These data support the hypothesis that glycosylation and adhesion pathways may broadly be involved in viral infection in Ae. aegypti. This article is protected by copyright. All rights reserved.
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.
Could Sterile Aedes albopictus Male Releases Interfere with Aedes aegypti Population in Reunion Island?
20229H. F. Andrianjakarivony, D. Damiens, L. Marquereau, B. Gaudillat, N. Habchi-Hanriot and L.-C. Gouagna, Insects, 13. 2022-01-29 08:58:23.
In Reunion Island, the feasibility of an Aedes albopictus control program using the Sterile Insect Technique (SIT) is studied. Because, in some regions, Ae. albopictus is living in sympatry with Aedes aegypti, the impact of releasing millions of sterile male Ae. albopictus on female Ae. aegypti reproduction needs to be assessed. Thus, to study the potential heterospecific matings, a marking technique using rhodamine B has been used. Rhodamine is given in solution to male mosquitoes to be incorporated into the male body and seminal fluid and transferred during mating into the bursa inseminalis and spermathecae of females. The presence of rhodamine in females occurred in 15% of cases when Ae. aegypti females were offered non-irradiated Ae. albopictus males, 5% when offered irradiated Ae. albopictus males and 18% of cases in the inverse heterospecific matings. Moreover, our results also showed that these matings gave few eggs but were not viable. Finally, the results showed that whatever the type of mating crosses, females in cages previously crossed with males of another species can re-mate with males of their species and produce an equivalent amount of egg compared to females only mated with conspecific males. Despite the promiscuity of the males and females in small cages for three days, heterospecific mating between sterile male Ae. albopictus and female Ae aegypti, 95% of the females have not been inseminated suggesting that in the field the frequency satyrization would be very low.
Effects of Sterile Males and Fertility of Infected Mosquitoes on Mosquito-Borne Disease Dynamics
20097X. L. Sun, S. Q. Liu, Y. F. Lv and Y. Z. Pei, Bulletin of Mathematical Biology, 84:33. 2022-01-13 09:37:31.
By studying an infection-age structured model, we consider the effects of releasing sterile males and the fertility of infected mosquitoes on the mosquito-borne diseases transmission including the extinction of mosquitoes, the elimination and persistence of diseases. Firstly, equivalent integral equations are established to prove the well-posedness of solutions. Then, the main results of disease dynamics are given. By taking chikungunya as a numerical simulation example, an optimal releasing threshold is given according to our presupposed control standard. When the fertility disturbance of infected mosquitoes is small, the high releasing amount plays a main role on the control of the disease; however, when the fertility disturbance is large, the initial distributions and the fertility of infected mosquitoes are the key factors to control the disease. Mathematically, the fertility of infected mosquitoes makes the system have complex dynamics with multiple positive equilibria and bistability.
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.
Introgression of the Aedes aegypti red-eye genetic sexing strains into different genomic backgrounds for sterile insect technique applications
20137A. A. Augustinos , K. Nikolouli , L. D. De La Fuente , M. Misbah-Ul-Haq, D. O. Carvalho and K. Bourtzis, Frontiers in Bioengineering and Biotechnology, 2022-01-11 13:16:31.
Aedes aegypti is an invasive mosquito species and major vector of human arboviruses. A wide variety of control methods have been employed to combat mosquito populations. One of them is the sterile insect technique (SIT) that has recently attracted considerable research efforts due to its proven record of success and the absence of harmful environmental footprints. The efficiency and cost-effectiveness of SIT is significantly enhanced by male-only releases. For mosquito SIT, male-only releases are ideally needed since females bite, blood-feed, and transmit the pathogens. Ae. aegypti genetic sexing strains (GSS) have recently become available and are based on eye color mutations that were chosen as selectable markers. These genetic sexing strains were developed through classical genetics and it was shown to be subjected to genetic recombination, a phenomenon that is not suppressed in males as is the case in many Diptera. The genetic stability of these GSS was strengthened by the induction and isolation of radiation-induced inversions. In this study, we used the red eye mutation and the inversion Inv35 line of the Ae. aegypti red-eye GSS s and introgressed them in six different genomic backgrounds to develop GSS with the respective local genomic backgrounds. Our goal was to assess whether the recombination frequencies in the strains with and without the inversion are affected by the different genomic backgrounds. In all cases the recombination events were suppressed in all Inv35 GSS strains, thus indicating that the genomic background does not negatively affect the inversion result. The absence of any effect that could be ascribed to genetic differences, enables the introgression of the key elements of the GSS into the local genomic background prior to release to the target areas. Maintaining the local background increases the chances for successful matings between released males and wild females and addresses potential regulatory concerns regarding biosafety and biosecurity.
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.
Determinants of stakeholders’ attitudes and intentions toward supporting the use of Wolbachia-infected Aedes mosquitoes for dengue control
19744A. F. Arham, L. Amin, M. A. C. Mustapa, Z. Mahadi, M. Yaacob and M. Ibrahim, BMC Public Health, 21:2314. 2021-12-23 13:22:08.
BACKGROUND: A recent approach in controlling dengue is by using the Wolbachia-infected Aedes mosquito (WiAM). The approach has been reported to be more effective than traditional methods, such as fogging. Therefore, it is imperative to assess the factors predicting its acceptance among stakeholders before implementing this technology more widely in Malaysia. METHODS: The survey data were collected from two primary stakeholder groups using a stratified random sampling technique. The two primary stakeholder groups were scientists (n = 202) and the public (n = 197) in the Klang Valley region of Malaysia, a hot spot area known for the high rate of dengue cases. The respondents answered questions on a seven-point Likert scale survey regarding trust in key players, attitudes toward nature versus materialism, religiosity, perceived benefits, perceived risks, attitudes, and intentions. The data were analyzed using Smart Partial Least Square (SmartPLS) software (version 3.2.6) to determine the predictors influencing attitudes and intentions to support the use of WiAM technology. RESULTS: The results indicated a strong positive relationship between attitudes and intentions to support the use of WiAM (β = 0.676, p < 0.001). The most important significant predictor for attitudes was perceived benefits (β = 0.493, p < 0.001), followed by perceived risks (β = - 0.080, p = 0.048). Trust in key players, attitudes toward nature versus material, and religiosity had indirect relationships with attitudes through the perceived benefits and risks. CONCLUSIONS: The identified predictors can serve as indicators for the decision-making process regarding WiAM implementation in Malaysia and other developing countries with similar demographics and cultures.
Temporal Viability of Aedes aegypti and Aedes albopictus Eggs Using Two Hygroscopic Substances as Preservatives under a Sterile Insect Technique (SIT) Program in Southern Mexico
19721E. N. Martínez-García, E. E. Díaz-González, C. F. Marina, J. G. Bond, J. J. Rodríguez-Rojas, G. Ponce-García, R. M. Sánchez-Casas and I. Fernández-Salas, Insects, 13. 2021-12-21 12:31:48.
Dengue and other Aedes-borne diseases have dramatically increased over the last decades. The Sterile Insect Technique (SIT) has been successfully used as part of integrated pest strategies to control populations of insect-plant and livestock pests and is currently being tested as a potential method to reduce mosquito populations in an environmentally friendly approach. However, during the mass rearing steps needed to produce millions of mosquitoes, egg storage and preservation are essential for a certain amount of time. Eggs of Aedes aegypti have a chorionic pad that functions as a sticky substance to glue them onto the inner walls of larval breeding sites. The chorionic pad is chemically made of hyaluronic acid, a hygroscopic compound, responsible to protect them from desiccation over time. Two commercial products with hygroscopic properties, hydrolyzed collagen, and Hyalurosmooth®, both were tested to assess their ability to prolong egg life storage for A. aegypti and A. albopictus. Results showed that 85–95% of Ae. aegypti eggs were able to hatch up to week 8 after being treated with both hydrophilic compounds, compared with the control 66.3%. These two substances showed promising effects for keeping Ae. aegypti eggs viable during prolonged storage in mass rearing insect production focused on vector control SIT programs.
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.
Aedes Control Using Sterile Insect Technique (SIT) in Malaysia
19973W. A. Nazni, G.-N. Teoh, S. I. Shaikh Norman Hakimi, M. A. Muhammad Arif, M. Tanusshni, M. A. Nuradila, A. Nurfarahin Hanini, I. A. Shazia, A.-M. Tan, H. Rabizah, M. D. Ahmad Zainuri, A. Hasnor Hadi, Y.-L. Cheong, A. Norazah, H. Maiga, R. S. Lees and L. H, Genetically Modified and other Innovative Vector Control Technologies, 2021-12-21 11:41:43.
The continued occurrence of massive outbreaks of Aedes-borne viral diseases of dengue, chikungunya, Zika and yellow fever, in spite of intensive and extensive application of conventional control measures, necessitates application of new tools, such as sterile insect technique (SIT), to stem the tide. Sterile insect technique is a form of biological control method, whereby sterile male insects are released in overwhelming numbers in the wild. These sterile males compete with the wild males to mate with the wild females. The females mated with sterile males will produce sterile eggs that will not hatch. Sustained release of sterile males over a period of time will lead to suppression or elimination of the natural population. Sterility is induced by gamma ray from the radioisotope of cobalt-60 and cesium-137 or X-ray. SIT is safe, cost-effective and environmentally non-polluting, and insects are unable to develop resistance to this method. SIT has a strong track record of success in elimination of agricultural pests, and this led to increased interest in using SIT against mosquitoes of public health importance. Studies and trials against Aedes were conducted in the 1960s and, more recently, against Ae. albopictus with promising results. Attempts were also made to apply SIT for the control of Aedes in several countries. Malaysia’s first experience with SIT was in the 1990s, when the Malaysian Nuclear Agency teamed with the MARDI and local universities to sterilise an agricultural pest, the diamondback moth. To prepare for the possible threat of introducing the Old World screw worm (Chrysomya bezziana) into Australia from neighbouring countries, from 1995 to 2000, Australia and Malaysia undertook a collaborative myiasis control research project located at the Institut Haiwan, Kluang, Malaysia. The project assisted in suppression trials of the screw worm in Malaysia and supported research that developed and evaluated improved Old World screw worm suppression and eradication techniques. In 2014, in collaboration with the Malaysian Nuclear Agency, the IMR conducted preliminary studies to determine the optimum sterilising dose of gamma irradiation against Ae. aegypti. In addition, the impact of sterilisation on the biological parameters of Ae. aegypti was also determined. The most effective sterilising dose that did not adversely affect the male was determined to be 55 Gy. Subsequently, a new initiative of field release of sterile Aedes aegypti males for the control of dengue was initiated in 2019. This 2-year programme will aim to release gamma ray-sterilised Ae. aegypti males in three trial sites to reduce the natural mosquito population to a level below the threshold required for dengue transmission. To ensure public acceptance, public engagement, a prerequisite for a successful release programme, will be conducted intensively prior to the release.
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.
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.
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
Genomic insertion locus and Cas9 expression in the germline affect CRISPR/Cas9-based gene drive performance in the yellow fever mosquito Aedes aegypti
19603W. R. Reid, J. Lin, A. E. Williams, R. Juncu, K. E. Olson and A. W. E. Franz, bioRxiv, 2021.12.08.471839. 2021-12-08 18:56:04.
The yellow fever mosquito Aedes aegypti is a major vector of arthropod-borne viruses, including dengue, chikungunya, and Zika. A novel approach to mitigate arboviral infections is to generate mosquitoes refractory to infection by overexpressing antiviral effector molecules. Such an approach requires a mechanism to spread these antiviral effectors through a population, for example, by using CRISPR/Cas9-based gene drive systems. Here we report an autonomous single-component gene drive system in Ae. aegypti that is designed for persistent population replacement. Critical to the design of a single-locus autonomous gene drive is that the selected genomic locus be amenable to both gene drive and the appropriate expression of the antiviral effector. In our study, we took a reverse engineering approach to target two genomic loci ideal for the expression of antiviral effectors and further investigated the use of three promoters for Cas9 expression (nanos, β2-tubulin, or zpg) for the gene drive. We found that both promoter selection and genomic target site strongly influenced the efficiency of the drive, resulting in 100% inheritance in some crosses. We also observed the formation of inheritable gene drive blocking indels (GDBI) in the genomic locus with the highest levels of gene drive. Overall, our drive system forms a platform for the further testing of driving antipathogen effector genes through Ae. aegypti populations.Competing Interest StatementThe authors have declared no competing interest.
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.
Combined sterile insect technique and incompatible insect technique: concept, study design, experience and lessons learned from a pilot suppression trial in Thailand
19367Kittayapong, P., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 16:50:12.
Climate change, rapid global transport and land use change leading to urbanization and agricultural intensification have facilitated disease emergence in vulnerable regions like Southeast Asia, and also the global expansion of vectors and vector-borne diseases into other regions like the Americas and Europe. Important vector-borne diseases, i.e. dengue, chikungunya, yellow fever, and Zika are transmitted by the major mosquito vector species, Aedes aegypti (L.) and Aedes albopictus (Skuse). Management of Ae. aegypti populations in countries endemic to these diseases, especially in Southeast Asia, is not sufficiently effective, resulting in high morbidity and mortality in the region. Insecticide resistance has become an important issue, causing failure in insecticide-based vector control. Innovative or alternative tools/approaches are needed to effectively reduce mosquito vector populations and consequently reduce the diseases they transmit. A trial integrating the environment-friendly Sterile Insect Technique (SIT) and the insect incompatible technique (IIT) was successfully carried out on a small-scale in a semi-rural setting in Thailand. In this chapter, we report on the design and methodology, as well as the experience and lessons learned from the baseline preparation and implementation of the pilot trial.
Ecology, behaviour and area-wide control of the floodwater mosquito Aedes sticticus, with potential of future integration of the sterile insect technique
19361Lundstrom, J. O. Schafer, M. L. Kittayapong, P., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 16:33:24.
The strategy of aerial control of the floodwater mosquito Aedes sticticus (Meigen) in the floodplains of River Dalalven, central Sweden, was developed to directly address specific larval breeding areas in temporary flooded wet meadows and swamps. Using the Bti-based larvicide VectoBac G (R), a very strong reduction of larval abundance is achieved, resulting in a massive decrease of blood-seeking females that could otherwise spread from the wetlands to feast on blood from humans and animals within 5 km or more from the larval biotopes. However, there is also a political demand to reduce the usage of the control agent through hypothetical alternatives, such as cattle grazing and mowing of the meadows, as well as hydrological changes of the River Dalalven. An evaluation of these measures showed that they are either insufficient or unrealistic in reducing floodwater mosquito abundance. Thus, we searched for other potential population suppression methods. Using the criteria of efficacy, environmental neutrality and compatibility within an integrated suppression approach, we conclude that Sterile Insect Technique (SIT) and the Incompatibility Insect Technique (IIT) would qualify for a pilot-scale test of their feasibility for the integrated control of the floodwater mosquito Ae. sticticus. The SIT and the IIT are similar strategies involving the release of sterile males which mate with local fertile females and result in infertile eggs. Prerequisites for a sterile male strategy to control Ae. sticticus include: a laboratory colony of the species, a facility for mass-rearing of mosquitoes, the sterilisation of males, a transport strategy, a dispersal system, assay systems for several life stages, and a method capable of reducing the population of this superabundant species before commencing the sterile male release. One factor in favour of implementing the SIT or IIT against Ae. sticticus is that mating occurs in or near well-defined larval breeding areas with specific relation to flood events. Another factor in favour of the SIT or the IIT is the availability of existing methods to measure gender, larvae and egg abundance. Also, existing Bti-treatments can substantially lower the population size before sterile male release. Other prerequisites, like the successful colonization of Ae. sticticus will require more tests and adaptations of existing mosquito rearing protocols. A pilot study is suggested for an isolated study area, protected from reinvasion by Ae. sticticus-females and included in routine Bti-treatments.
Major phase of Florida Keys GMO mosquito release complete, company says
19393D. Goodhue, Miami Herald, 2021-11-23 17:29:49.
A British biotechnology company and the Florida Keys Mosquito Control District on Tuesday announced they have “successfully concluded” a major phase in a controversial trial project aimed at wiping out an invasive species of mosquito known to spread dangerous diseases like dengue fever, Zika and chikungunya. In April, the company, Oxitec, placed up to 130 boxes, each filled with millions of genetically altered male Aedes aegypti mosquito larvae, in several locations in the Middle and Lower Keys — hoping they would fly away after hatching and breeding with the naturally occurring local females in the area. Scientists designed a “death mechanism” in the males meant to ensure no viable female offspring would result from the mating. The male offspring, according to Oxitec, will pass on a “self-limiting gene” to half of their young, with the goal of Aedes aegypti breeding themselves out of existence in the Keys, according to the company.
Evaluation of Transgenic Aedes aegypti L. Strain in India: A Friendly Mosquito
19979P. B. Patil, K. K. Yadav, S. K. Dasgupta, U. B. Zehr, S. R. Barwale and B. Char, Genetically Modified and other Innovative Vector Control Technologies, 2021-11-21 11:56:31.
Aedes aegypti L. is a primary vector of dengue and is also responsible for transmission of other arboviral diseases including chikungunya, yellow fever, and Zika virus worldwide. India is attributed with as much as 34% of the global burden of dengue infection as per the recent reports. It is generally acknowledged controlling the vector population in the environment is the key to effectively curb the transmission of vector-borne diseases. Existing conventional methods for controlling the vector populations are not alone sufficient for reducing populations below disease transmission thresholds and would need integration of innovative strategies. With the advancement in modern biotechnology, scientists have been trying to explore the use of genetically engineered insects for their potential use in area-wide method for vector control. One among such strains being widely tested is OX513A Ae. aegypti strain termed as Friendly™ mosquitoes, a genetically engineered strain with a repressible dominant homozygous lethal gene construct and DsRed2 fluorescent marker gene. Male adults of OX513A strain are intended to suppress the wild population of Ae. aegypti in the released environment by population suppression strategy. The lethal gene renders mating events between OX513A males and wild-type females unsuccessful by passing a copy of gene to all the progeny of mated female adults leading to the death of the progeny during development stages in the absence of repressor antidote tetracycline. This OX513A strain was reviewed and recommended for carefully planned pilot deployment and randomized control trials with epidemiological outcomes to build evidence for routine programmatic use against Ae. aegypti-borne diseases by World Health Organization’s Vector Control Advisory Group in the year 2016. The strain is being tested globally in different countries including India for its efficacy and has been deregulated in Brazil for its use in vector control program. This chapter reviews our research investigations conducted on transgenic OX513A Ae. aegypti strain and its potential for use in dengue vector control in India.
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.
High Temperature Cycles Result in Maternal Transmission and Dengue Infection Differences Between Wolbachia Strains in Aedes aegypti
19221M. V. Mancini, T. H. Ant, C. S. Herd, J. Martinez, S. M. Murdochy, D. D. Gingell, E. Mararo, P. C. D. Johnson and S. P. Sinkins, mBio, e0025021. 2021-11-10 21:39:39.
Environmental factors play a crucial role in the population dynamics of arthropod endosymbionts, and therefore in the deployment of Wolbachia symbionts for the control of dengue arboviruses. The potential of Wolbachia to invade, persist, and block virus transmission depends in part on its intracellular density. Several recent studies have highlighted the importance of larval rearing temperature in modulating Wolbachia densities in adults, suggesting that elevated temperatures can severely impact some strains, while having little effect on others. The effect of a replicated tropical heat cycle on Wolbachia density and levels of virus blocking was assessed using Aedes aegypti lines carrying strains wMel and wAlbB, two Wolbachia strains currently used for dengue control. Impacts on intracellular density, maternal transmission fidelity, and dengue inhibition capacity were observed for wMel. In contrast, wAlbB-carrying Ae. aegypti maintained a relatively constant intracellular density at high temperatures and conserved its capacity to inhibit dengue. Following larval heat treatment, wMel showed a degree of density recovery in aging adults, although this was compromised by elevated air temperatures. IMPORTANCE In the past decades, dengue incidence has dramatically increased all over the world. An emerging dengue control strategy utilizes Aedes aegypti mosquitoes artificially transinfected with the bacterial symbiont Wolbachia, with the ultimate aim of replacing wild mosquito populations. However, the rearing temperature of mosquito larvae is known to impact on some Wolbachia strains. In this study, we compared the effects of a temperature cycle mimicking natural breeding sites in tropical climates on two Wolbachia strains, currently used for open field trials. When choosing the Wolbachia strain to be used in a dengue control program it is important to consider the effects of environmental temperatures on invasiveness and virus inhibition. These results underline the significance of understanding the impact of environmental factors on released mosquitoes, in order to ensure the most efficient strategy for dengue control.
The drone, the tool of the future to combat its spread
19234T. Thompson, Your Decommissioning News, 2021-11-09 22:01:19.
Drones could become a promising tool in the fight against the tiger mosquito, according to a study published Tuesday by French researchers. French researchers said on Tuesday that drones could, within a few years, integrate into the arsenal of the fight against the tiger mosquito, an invasive species that appeared on mainland France about fifteen years ago, revealing the results of an experiment conducted in Montpellier. The tiger mosquito, Aedes albopictus, now detected in 65 French departments, grows at 80% in individuals, mainly in standing water in gardens. It is more harmful because it stings constantly during the day and can transmit viral diseases such as dengue, chikungunya or Zika if it has been stung by a previous patient. Therefore the first preventive measure against this insect, whose reproduction is preferred by high temperatures, is to systematically empty and overturn containers that may contain water, such as a simple ashtray. But additional methods have emerged in recent years, including the so-called “sterile insect technique” (TIS), which consists of raising male mosquitoes in laboratories, sterilizing them, and then releasing them into the field, where wild females are sterilized. which will not have offspring.
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!”
Prevalence and molecular characterization of Wolbachia in field-collected Aedes albopictus, Anopheles sinensis, Armigeres subalbatus, Culex pipiens and Cx. tritaeniorhynchus in China
19078Y. Yang, Y. He, G. Zhu, J. Zhang, Z. Gong, S. Huang, G. Lu, Y. Peng, Y. Meng, X. Hao, C. Wang, J. Sun and S. Shang, PLOS Neglected Tropical Diseases, 15:e0009911. 2021-10-29 20:41:21.
Wolbachia are maternally transmitted intracellular bacteria that can naturally and artificially infect arthropods and nematodes. Recently, they were applied to control the spread of mosquito-borne pathogens by causing cytoplasmic incompatibility (CI) between germ cells of females and males. The ability of Wolbachia to induce CI is based on the prevalence and polymorphism of Wolbachia in natural populations of mosquitoes. In this study, we screened the natural infection level and diversity of Wolbachia in field-collected mosquitoes from 25 provinces of China based on partial sequence of Wolbachia surface protein (wsp) gene and multilocus sequence typing (MLST). Among the samples, 2489 mosquitoes were captured from 24 provinces between July and September, 2014 and the remaining 1025 mosquitoes were collected month-by-month in Yangzhou, Jiangsu province between September 2013 and August 2014. Our results showed that the presence of Wolbachia was observed in mosquitoes of Aedes albopictus (97.1%, 331/341), Armigeres subalbatus (95.8%, 481/502), Culex pipiens (87.0%, 1525/1752), Cx. tritaeniorhynchus (17.1%, 14/82), but not Anopheles sinensis (n = 88). Phylogenetic analysis indicated that high polymorphism of wsp and MLST loci was observed in Ae. albopictus mosquitoes, while no or low polymorphisms were in Ar. subalbatus and Cx. pipiens mosquitoes. A total of 12 unique mutations of deduced amino acid were identified in the wsp sequences obtained in this study, including four mutations in Wolbachia supergroup A and eight mutations in supergroup B. This study revealed the prevalence and polymorphism of Wolbachia in mosquitoes in large-scale regions of China and will provide some useful information when performing Wolbachia-based mosquito biocontrol strategies in China.
Wolbachia goes to work in the war on mosquitoes
19076S. Ong, Nature, 598:S32-s34. 2021-10-29 20:37:48.
There are two approaches to tackling dengue with Wolbachia. The first involves releasing only modified male mosquitoes. Since 2015, this strategy has been successfully adopted in Singapore and Guangzhou, China, and in parts of the United States, such as Miami, Texas and California. Because eggs produced from unmodified females that mate with modified males do not hatch, the number of mosquitoes in the community is greatly reduced. The second approach, used by some cities in Vietnam, Indonesia, Malaysia, Brazil and Australia, among others, involves releasing modified mosquitoes of both sexes. The infected females pass the bacteria to their offspring. Over time (several months to years, depending on characteristics of the release site), the modified mosquitoes replace the native population.
Novel Symbiotic Genome-Scale Model Reveals Wolbachia’s Arboviral Pathogen Blocking Mechanism in Aedes aegypti
18936N. E. Jiménez, Z. P. Gerdtzen, Á. Olivera-Nappa, J. C. Salgado and C. Conca, mBio, e0156321. 2021-10-13 20:29:16.
Arboviral diseases such as Zika and Dengue have been on the rise mainly due to climate change, and the development of new treatments and strategies to limit their spreading is needed. The use of Wolbachia as an approach for disease control has motivated new research related to the characterization of the mechanisms that underlie its pathogen-blocking properties. In this work, we propose a new approach for studying the metabolic interactions between Aedes aegypti and Wolbachia using genome-scale models, finding that pathogen blocking is mainly influenced by competition for the resources required for Wolbachia and viral replication.
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.
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. ...
Novel Sterile Insect Technology Program Results in Suppression of a Field Mosquito Population and Subsequently to Reduced Incidence of Dengue
30892Lisiane de Castro Poncio, Filipe Apolinário dos Anjos, Deborah A de Oliveira, Débora Rebechi, et al., The Journal of Infectious Diseases, 224:1005-1014. 2021-09-15 08:29:17.
There is a steady rise in the global incidence of Aedes-borne arbovirus disease. It has become urgent to develop alternative solutions for mosquito vector control. We developed a new method of sterilization of male mosquitoes with the goal to suppress a local Aedes aegypti population and to prevent the spread of dengue. Sterile male mosquitoes were produced from a locally acquired Ae. aegypti colony by using a treatment that includes double-stranded RNA and thiotepa. A field study was conducted with sterile mosquito releases being performed on a weekly basis in predefined areas. There were 2 intervention periods (INT1 and INT2), with treatment and control areas reversed between INT1 and INT2. During INT1, releases in the treated area resulted in up to 91.4% reduction of live progeny of field Ae. aegypti mosquitoes recorded over time, while the control neighborhoods (no releases of sterile male mosquitoes) remained highly infested. The successful implementations of the program during INT1 and INT2 were associated with 15.9-fold and 13.7-fold lower incidences of dengue in the treated area compared to the control areas, respectively. Our data show the success of this new sterile insect technology-based program in preventing the spread of dengue.
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.”
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.
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.
Assessment of fitness and vector competence of a New Caledonia wMel Aedes aegypti strain before field-release
18360N. Pocquet, O. O’Connor, H. A. Flores, J. Tutagata, M. Pol, D. J. Hooker, C. Inizan, S. Russet, J. M. Duyvestyn, E. C. Pacidônio, D. Girault, D. da Silva Gonçalves, M. Minier, F. Touzain, E. Chalus, K. Lucien, F. Cheilan, T. Derycke, S. Laumond, C. P. Sim, PLOS Neglected Tropical Diseases, 15:e0009752. 2021-09-07 14:13:26.
Dengue represents a risk for almost half of the world’s population, especially throughout the tropics. In New Caledonia, dengue outbreaks have become more frequent in the past decade along with the recent circulation of chikungunya and Zika viruses. The opportunity to use the biocontrol method involving the release of Wolbachia-infected Ae. aegypti mosquitoes has been investigated as an alternative solution to the traditional control methods, like elimination of larval habitats and pyrethroid insecticide application to kill adults, which are becoming insufficient. A local strain of Ae. aegypti carrying Wolbachia (NC-wMel) has been generated and tested to evaluate its pathogen blocking capacity for the four dengue virus serotypes as well as chikungunya and Zika viruses. The fitness of NC-wMel strain has also been assessed to estimate its ability to compete with the wild-type strain in the field. Noumea city, where a third of the population of New Caledonia resides, has been chosen as the first site to implement the method in New Caledonia. As Ae. aegypti is the only proven vector in New Caledonia, we expect a significant impact on dengue outbreaks occurring in Noumea as soon as a high frequency of NC-wMel is established in the population.
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).
wMel Wolbachia genome remains stable after 7 years in Australian Aedes aegypti field populations
18281K. R. Dainty, J. Hawkey, L. M. Judd, E. C. Pacidônio, J. M. Duyvestyn, D. S. Gonçalves, S. Y. Lin, T. B. O'Donnell, S. L. O'Neill, C. P. Simmons, K. E. Holt and H. A. Flores, Microbial Genomics, 7. 2021-09-02 14:23:53.
Infection of wMel Wolbachia in Aedes aegypti imparts two signature features that enable its application for biocontrol of dengue. First, the susceptibility of mosquitoes to viruses such as dengue and Zika is reduced. Second, a reproductive manipulation is caused that enables wMel introgression into wild-type mosquito populations. The long-term success of this method relies, in part, on evolution of the wMel genome not compromising the critical features that make it an attractive biocontrol tool. This study compared the wMel Wolbachia genome at the time of initial releases and 1-7 years post-release in Cairns, Australia. Our results show the wMel genome remains highly conserved up to 7 years post-release in gene sequence, content, synteny and structure. This work suggests the wMel genome is stable in its new mosquito host and, therefore, provides reassurance on the potential for wMel to deliver long-term public-health impacts.
EPA Seeks Public Comment on Proposed Amendment to Experimental Use Permit for Genetically Engineered Mosquitoes
18279PCT Staff, Pest Control Technology, 2021-09-01 14:19:37.
EPA is seeking public comment on a proposed amendment to extend and expand an approved Experimental Use Permit (EUP). The EUP currently allows Oxitec Ltd. to field test the use of genetically engineered Aedes aegypti mosquitoes as a way to reduce mosquito populations in Florida and Texas through April 2022. The proposed amendment would extend field testing in Florida by another 24 months on up to 6,240 acres and expand testing to California on up 84,600 acres. This amendment is still being reviewed by EPA and has not yet been approved. Once EPA finishes reviewing the proposed amendment and public comments, EPA will make a decision about whether to extend and expand the EUP. In May 2020, EPA granted Oxitec’s EUP after extensive evaluation of the best available science, consideration of public input, and consultation with technical experts at the U.S. Centers for Disease Control and Prevention (CDC). Starting in late April 2021, Oxitec has been measuring how effective OX5034 genetically engineered mosquitoes are in suppressing Aedes aegypti mosquito populations in Florida. They release genetically engineered male mosquitoes that have a gene that makes a specific protein. This protein, as produced in female mosquitoes, prevents female offspring from surviving. The absence of female mosquito emergence in the release area results in mosquito population decline, and potentially, the reduction of vector pathogens that cause mosquito-borne illnesses such as the dengue, Zika and chikungunya viruses.
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.
Mobilizing Mutant Mosquitoes to Fight Malaria
18227D. Mclaughlin and J. Recht, United Nations Foundation, 2021-08-18 15:49:29.
World Mosquito Day today marks the 1897 discovery by Sir Ronald Ross that female Anopheles mosquitoes spread malaria. Since that breakthrough, the world has fought this deadly disease through scientific research and new technology. While astounding progress has been made against the ancient disease, more than 400,000 people died from malaria in 2019, two-thirds of them children under 5, the vast majority in Africa.Existing malaria controls such as spraying insecticides indoors or sleeping beneath long-lasting insecticidal bed nets work by blocking mosquitoes from biting people and transmitting malaria. Such tools have helped halve malaria in many countries throughout sub-Saharan Africa. Yet this remarkable progress is in jeopardy as mosquitoes develop resistance to these insecticides. As the dangerous mosquito continues to adapt, health interventions must continue evolving to protect families from this disease and move us closer to a malaria-free world. Now, there is a promising new tool, seemingly ripped from the pages of a science fiction novel, to stop malaria’s spread: genetically modified 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.
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.
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.
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.
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.
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.
A wAlbB Wolbachia< transinfection displays stable phenotypic effects across divergent Aedes aegypti mosquito backgrounds
17592P. A. Ross, X. Gu, K. L. Robinson, Q. Yang, E. Cottingham, Y. Zhang, H. L. Yeap, X. Xu, N. M. Endersby-Harshman and A. A. Hoffmann, bioRxiv, 2021.06.25.450002. 2021-06-26 14:00:37.
Aedes mosquitoes harboring intracellular Wolbachia bacteria are being released in arbovirus and mosquito control programs. With releases taking place around the world, understanding the contribution of host variation to Wolbachia phenotype is crucial. We generated a Wolbachia transinfection (wAlbBQ) in Aedes aegypti and performed backcrossing to introduce the infection into Australian or Malaysian nuclear backgrounds. Whole Wolbachia genome sequencing shows that the wAlbBQ transinfection is near-identical to the reference wAlbB genome, suggesting few changes since the infection was first introduced to Ae. aegypti over 15 years ago. However, these sequences were distinct from other available wAlbB genome sequences, highlighting the potential diversity of wAlbB in natural Ae. albopictus populations. Phenotypic comparisons demonstrate effects of wAlbB infection on egg hatch and nuclear background on fecundity and body size, but no interactions between wAlbB infection and nuclear background for any trait. The wAlbB infection was stable at high temperatures and showed perfect maternal transmission and cytoplasmic incompatibility regardless of host background. Our results demonstrate the stability of wAlbB across host backgrounds and point to its long-term effectiveness for controlling arbovirus transmission and mosquito populations.Competing Interest StatementThe authors have declared no competing interest.
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%.
Wolbachia-mediated sterility suppresses Aedes aegypti populations in the urban tropics
19443Project Wolbachia-Singapore Consortium, medRxiv, 2021-06-17 21:07:26.
Incompatible insect technique (IIT) via releases of male Wolbachiainfected mosquitoes is a promising tool for dengue control. In a three-year trial in Singaporean high-rise housing estates, we demonstrated that Wolbachia-based IIT dramatically reduces both wildtype Aedes aegypti populations [reductions of 92.7% (95% CI: 84.7%–95.8%) and 98.3% (97.7%–99.8%)] and dengue incidence [reductions of 71% (43%-87%) to 88% (57%-99%)] in the targeted areas. The study highlights the need to ensure adequate vertical distribution of released males in high-rise buildings, address immigration of wildtype females from neighboring areas, and prevent and mitigate stable establishment of Wolbachia in field mosquito populations. Our results demonstrate the potential of Wolbachia-based IIT (supplemented with irradiation, in Singapore’s context) for strengthening dengue control in tropical cities, where dengue burden is the greatest.
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.
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.
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.
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.
Genetically Altered Mosquitoes Target Deadly Dengue Fever and Zika
17174R. L. Hotz, Wall Street Journal, 2021-05-31 19:52:20.
Across the Florida Keys this week, newly hatched mosquitoes are swarming from damp flowerpots, waterlogged spare tires, trash cans and drainage ditches. In six neighborhoods, however, a change is buzzing in the air. Scientists have genetically modified thousands of these mosquitoes and, for the first time in the U.S., set them free to breed. These genetically engineered insects, known by their model number as OX5034, are a laboratory offshoot of the Aedes aegypti mosquito that transmits dengue, Zika and other infectious ills. After a decade of public debate and regulatory delays, these insects are being released by a U.K. biotechnology company called Oxitec. Using genetic-engineering techniques, the company altered the male mosquitoes to pass down a gene that makes females need a dash of the antibiotic tetracycline to survive. Without it, females that spread the disease die as larvae. Altered males, which don’t bite, seek out wild females to mate and spread the lethal trait to future generations. Gradually, more females die. The swarms dwindle and disappear, with no need for chemical insecticides.
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.
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.
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.
Genetically Modified Mosquitoes: What to Know
17138N. Pathak, WebMD, 2021-05-25 13:11:47.
It sounds like something out of a movie: a biotech company releases genetically modified mosquitoes into the wild. But this is the real deal, a test that’s been done in a handful of countries around the world and that is underway in the U.S. Scientists hope these bugs can help them stop the spread of some dangerous viruses over time. What Is a Genetically Modified Mosquito? There are more than 200 types of wild mosquitoes buzzing around America and the U.S. territories. One type that’s common in many parts of the country, Aedes aegypti, can spread diseases like dengue, Zika, yellow fever, and chikungunya through its bite.Aedes aegypti mosquitoes that have had their genes changed in a lab are intended to control the disease-carrying wild ones. It’s a possible alternative to insecticides, which are used so much in the U.S. that some mosquitoes have become resistant to them, meaning they shrug off the deadly effects. And certain insecticides can be toxic to beneficial bugs like bees.
Sterilizing skeeters using CRISPR/Cas9
17117H. Tasoff, Phy Org, 2021-05-24 18:45:33.
Mosquitoes are one of humanity's greatest nemeses, estimated to spread infections to nearly 700 million people per year and cause more than one million deaths. UC Santa Barbara Distinguished Professor Craig Montell has made a breakthrough in one technique for controlling populations of Aedes aegypti, a mosquito that transmits dengue, yellow fever, Zika and other viruses. The study, published in the Proceedings of the National Academy of Sciences, documents the first use of CRISPR/Cas9 gene editing to target a specific gene tied to fertility in male mosquitoes. The researchers were then able to discern how this mutation can suppress the fertility of female mosquitoes. Montell and his coauthors were working to improve a vector-control practice called the sterile insect technique (SIT). To manage populations, scientists raise a lot of sterile male insects. They then release these males in numbers that overwhelm their wild counterparts. The idea is that 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. What's more, because each generation is smaller than the last, releasing a similar number of sterile males has a stronger effect over time.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.”
Sterile Insect Technique in an Integrated Vector Management Program against Tiger Mosquito Aedes albopictus in the Valencia Region (Spain): Operating Procedures and Quality Control Parameters
16663C. Tur, D. Almenar, S. Benlloch-Navarro, R. Argilés-Herrero, M. Zacarés, V. Dalmau and I. Pla, Insects, 12. 2021-03-23 14:20:04.
The Agriculture Department of the Valencian Region is promoting an ongoing pilot project to evaluate the efficacy of an integrated vector management program (IVM) based on the use of the SIT as the main method of control. The laboratory studies for evaluating the entomological efficacy of SIT through the phased conditional testing process recommended by World Health Organization and the International Atomic Energy Agency (WHO-IAEA) are addressed. This study describes the routine operating procedures and quality control parameters for the medium-scale rearing of sterile male A. albopictus. More than 15 million sterile males have been produced and released in an area of 80 ha between 2018 and 2020. Of the initial L1 larvae, we recovered 17.2% of male pupae after sex sorting to be sterilized and released on the field, while the rest of the pupae remained available to maintain the rearing colony. The residual percentage of females after sex sorting was on average 0.17%. The obtained values in terms of production and quality control as well as the proposed rearing methodology can be useful for designing a medium-scale mosquito-rearing pipeline.
Current Effector and Gene-Drive Developments to Engineer Arbovirus-Resistant Aedes aegypti (Diptera: Culicidae) for a Sustainable Population Replacement Strategy in the Field
16596W. R. Reid, K. E. Olson and A. W. E. Franz, J Med Entomol, 2021-03-12 20:35:28.
Conventional mosquito control efforts based on insecticide treatments and/or the use of bednets and window curtains are currently insufficient to reduce arbovirus prevalence in affected regions. Novel, genetic strategies that are being developed involve the genetic manipulation of mosquitoes for population reduction and population replacement purposes. Population replacement aims at replacing arbovirus-susceptible wild-type mosquitoes in a target region with those that carry a laboratory-engineered antiviral effector to interrupt arboviral transmission in the field.
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.
Eliminating Mosquitoes with Precision Guided Sterile Males
16563M. 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. Sanchez C, J. B. Bennett, I. Antoshechkin, C. Montell, J. M. Marshall and O. S. Akbari, bioRxiv, 2021.03.05.434167. 2021-03-06 20:07:26.
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 sterile males that are deployable at any life stage. Supported by mathematical models, we empirically demonstrate that released pgSIT males can compete, suppress, and eliminate mosquitoes in multigenerational population cages. 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.
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.
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.
Knowledge, Attitude, and Practices Survey in Greece before the Implementation of Sterile Insect Technique against Aedes albopictus
16661A. Stefopoulou, S. L. LaDeau, N. Syrigou, G. Balatsos, V. Karras, I. Lytra, E. Boukouvala, D. P. Papachristos, P. G. Milonas, A. Kapranas, P. Vahamidis and A. Michaelakis, Insects, 12. 2021-03-02 13:52:16.
A KAP tool was used to shed light on the knowledge, practices, and attitudes of local community members in order to better prepare and motivate participation in household mosquito control and to assess current understanding of SIT. Each household also received specific information about mosquito source habitat in their own yards at the time of the initial KAP survey. These household data were complemented by standardized mosquito trapping in the municipality. Our findings indicate that citizens’ attitude toward SIT ranged from indecisive to fully supportive, while 77.5% of the respondents agreed that the SIT has many advantages over chemical control methods. Furthermore, the results demonstrate that using the door-to-door campaign as an intervention and prerelease method before SIT can suppress the initial mosquito population and potentially improve its efficacy. Lastly, we show that the presence of local municipality officials during door-to-door visits was associated with increased willingness from the residents to participate in the intervention.
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 (SIT) against Aedes Species Mosquitoes: A Roadmap and Good Practice Framework for Designing, Implementing and Evaluating Pilot Field Trials
16659C. F. Oliva, M. Q. Benedict, C. M. Collins, T. Baldet, R. Bellini, H. Bossin, J. Bouyer, V. Corbel, L. Facchinelli, F. Fouque, M. Geier, A. Michaelakis, D. Roiz, F. Simard, C. Tur and L.-C. Gouagna, Insects, 12. 2021-02-24 13:44:35.
We offer here a pragmatic and accessible ‘roadmap’ for the pre-pilot and pilot phases to guide any interested party. This will support stakeholders, non-specialist scientists, implementers, and decision-makers. Applying these concepts will ensure, given adequate resources, a sound basis for local field trialing and for developing experience with the technique in readiness for potential operational deployment. This synthesis is based on the available literature, in addition to the experience and current knowledge of the expert contributing authors in this field. We describe a typical path to successful pilot testing, with the four concurrent development streams of Laboratory, Field, Stakeholder Relations, and the Business and Compliance Case. We provide a graphic framework with criteria that must be met in order to proceed.
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.
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.
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.
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.
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.
Sexual Competitiveness and Induced Egg Sterility by Aedes aegypti and Aedes albopictus Gamma-Irradiated Males: A Laboratory and Field Study in Mexico
17760J. G. Bond, S. Aguirre-Ibáñez, A. R. Osorio, C. F. Marina, Y. Gómez-Simuta, R. Tamayo-Escobar, A. Dor, P. Liedo, D. O. Carvalho and T. Williams, Insects, 12. 2021-01-29 14:44:07.
The sterile insect technique may prove useful for the suppression of mosquito vectors of medical importance in regions where arboviruses pose a serious public health threat. In the present study, we examined the effects of sterilizing irradiation doses across different ratios of fertile:irradiated males on the mating competitiveness of Ae. aegypti and Ae. albopictus under laboratory and field-cage conditions. For both species, the percentage of females inseminated and the number of eggs laid over two gonotrophic cycles varied significantly in mating treatments involving 1:1, 1:5, and 1:10 fertile:irradiated males compared to controls of entirely fertile or entirely irradiated males but was not generally affected by the irradiation dose. Egg hatching was negatively affected in females exposed to increasing proportions of irradiated males in both laboratory and field cages. Male competitiveness (Fried’s index) values varied from 0.19 to 0.58 in the laboratory and were between 0.09 and 1.0 in field cages, depending on th species. Competitiveness values were negatively affected by th eirradiation dose in both species under field-cage conditions, whereas in the laboratory, Ae. albopictus was sensitive to the dose but Ae. aegypti was not. In general, male competitiveness was similar across all mating regimes. Most importantly, induced egg sterility was positively correlated with the proportion of irradiated males present in the mating treatments, reaching a maximum of 88% under field-cage conditions for both Ae. aegypti and Ae. albopictus males treated with 50 and 40 Gy irradiation, respectively. These results indicate that sterile males produced at our facility are suitable and competitive enough for field pilot SIT projects and provide guidance to decide the optimal sterile:fertile ratios.
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.
‘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.
Edit, undo: Temporary gene editing could help solve the mosquito problem
15900L. Dormehl, digitaltrends, 2020-12-31 14:22:29.
But if SyFy original movies have taught us anything, it’s that genetically tweaking organisms and then releasing them can… well, not go quite according to plan.With that in mind, a new Texas A&M AgriLife Research project seeks to test out genetic modifications of mosquitos that would delete themselves from the genetic code after a certain period. This means that “test runs” of genetic changes could be made, knowing that everything will reset to normal after a designated period like one year (which equates to around 20 generations of mosquito).
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.
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.
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 CRISPR endonuclease gene drive reveals two distinct mechanisms of inheritance bias
15480S. A. N. Verkuijl, E. González, J. X. D. Ang, M. Li, N. P. Kandul, M. Anderson, O. S. Akbari, M. Bonsall and L. Alphey, bioRxiv, 2020.12.15.421271. 2020-12-16 14:45:08.
In this study, we report the functioning of sds3, bgcn, and nup50 expressed Cas9 in an Aedes aegypti homing split drive system targeting the white gene. We report their inheritance biasing capability, propensity for maternal deposition, and zygotic/somatic expression. Additionally, by making use of the tight linkage of white to the sex-determining locus, we were able to elucidate mechanisms of inheritance bias. We find inheritance bias through homing in double heterozygous males, but find that a previous report of the same drive occurred through meiotic drive. We propose that other previously reported 'homing'design gene drives may in fact bias their inheritance through other mechanisms with important implications for gene drive design.Competing Interest StatementThe authors have declared no competing interest.
The Antiviral Small-Interfering RNA Pathway Induces Zika Virus Resistance in Transgenic Aedes aegypti
15482A. E. Williams, I. Sanchez-Vargas, W. R. Reid, J. Y. Lin, A. W. E. Franz and K. E. Olson, Viruses, 12:18. 2020-12-15 14:45:29.
We used CRISPR/Cas9 to re-target a previously characterized locus (Chr2:321382225) and engineered mosquitoes expressing an inverted repeat (IR) dsRNA against the NS3/4A region of the ZIKV genome. Small RNA analysis revealed that the IR effector triggered the mosquito's siRNA antiviral pathway in bloodfed females. Nearly complete (90%) inhibition of ZIKV replication was found in vivo in both midguts and carcasses at 7 or 14 days post-infection (dpi). Furthermore, significantly fewer transgenic mosquitoes contained ZIKV in their salivary glands (p = 0.001), which led to a reduction in the number of ZIKV-containing saliva samples as measured by transmission assay. Our work shows that Ae. aegypti innate immunity can be co-opted to engineer mosquitoes resistant to ZIKV.
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.
Modelling the Wolbachia incompatible insect technique: strategies for effective mosquito population elimination
15281D. E. Pagendam, B. J. Trewin, N. Snoad, S. A. Ritchie, A. A. Hoffmann, K. M. Staunton, C. Paton and N. Beebe, BMC Biology, 18:13. 2020-12-02 16:29:23.
We introduce a simple Markov population process model for studying mosquito populations subjected to a Wolbachia-IIT programme which exhibit an unstable equilibrium threshold. The model is used to study, in silico, scenarios that are likely to yield a successful elimination result. Our results suggest that elimination is best achieved by releasing males at rates that adapt to the ever-decreasing wild population, thus reducing the risk of releasing Wolbachia-infected females while reducing costs.
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.
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
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
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.
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?
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.
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.
Cytoplasmic incompatibility: an autocidal mechanism for mosquito population control
13893V. Dev, BugBitten BMC, 2020-08-18 13:23:13.
Cytoplasmic incompatibility resulting in non-reciprocal fertility is a naturally occurring phenomenon, but remains unexplored to greater extent for the control of insect vector populations. This mechanism deserves priority for mosquito control and reducing disease transmission, being non-insecticidal and easier to operate with minimal investments.
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.
Incorporating Characteristics of Gene Drive Engineered Ae. aegypti as Methods to Reduce Dengue and Zika Virus into the Bayesian Network – Relative Risk Model, Using Ponce, Puerto Rico as a Case Study
16097S. R. Eikenbary, WWU Graduate School Collection, 2020-08-10 19:24:02.
The Bayesian network relative risk model can perform the risk assessment of gene drive engineered Ae. aegypti for vector control and as part of an adaptive management strategy to reduce dengue and Zika transmission. This study illustrates how the BN-RRM can integrate gene drive related information within a risk assessment framework suitable for adaptive management of these novel stressors.
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.
Genetically modified mosquitoes could be released in Florida
13587wqad.com, WQAD8, 2020-07-30 12:51:49.
Cases of dengue fever are on the rise in the Florida Keys. One biotech company wants to release genetically modified mosquitoes for a pilot program.
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.
EPA approves field trials of genetically modified mosquito
13449A. Wernick, WBFO npr, 2020-07-17 16:18:01.
The Environmental Protection Agency has given biotech company Oxitec the go-ahead to test the effectiveness of genetically modified mosquitoes in parts of Florida and Texas. Oxitec has been developing genetically modified mosquitoes in hopes of reducing local populations of mosquitoes that carry dengue fever, yellow fever and the Zika virus. About 750,000 people die each year from mosquito-borne illnesses, making the insect indirectly responsible for more human deaths than any other animal in the world.
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.
Artificial Selection Finds New Hypotheses for the Mechanism of Wolbachia-Mediated Dengue Blocking in Mosquitoes
13600S. A. Ford, I. Albert, S. L. Allen, S. F. Chenoweth, M. Jones, C. Koh, A. Sebastian, L. T. Sigle and E. A. McGraw, Frontiers in Microbiology, 11:1456. 2020-07-07 13:18:12.
We recently used experimental evolution to reveal that Wolbachia-mediated dengue blocking could be selected upon in the A. aegypti host and showed evidence that strong levels of blocking could be maintained by natural selection. In this study, we investigate the genetic variation associated with blocking and use these analyses to generate testable hypotheses surrounding the mechanism of Wolbachia-mediated dengue blocking.
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.
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.
Field performance of sterile male mosquitoes released from an uncrewed aerial vehicle
12708J. Bouyer, N. J. Culbert, A. H. Dicko, M. G. Pacheco, J. Virginio, M. C. Pedrosa, L. Garziera, A. T. M. Pinto, A. Klaptocz, J. Germann, T. Wallner, G. Salvador-Herranz, R. A. Herrero, H. Yamada, F. Balestrino and M. J. B. Vreysen, Science Robotics, 5:10. 2020-06-15 20:48:48.
Genetic control methods of mosquito vectors of malaria, dengue, yellow fever, and Zika are becoming increasingly popular due to the limitations of other techniques such as the use of insecticides. The sterile insect technique is an effective genetic control method to manage insect populations. However, it is crucial to release sterile mosquitoes by air to ensure homogeneous coverage, especially in large areas. Here, we report a fully automated adult mosquito release system operated from an uncrewed aerial vehicle or drone. Our system, developed and tested in Brazil, enabled a homogeneous dispersal of sterile male Aedes aegypti while maintaining their quality, leading to a homogeneous sterile-to-wild male ratio due to their aggregation in the same sites. Our results indicate that the released sterile males were able to compete with the wild males in mating with the wild females; thus, the sterile males were able to induce sterility in the native female population. The use of drones to implement the sterile insect technique will lead to improvements in areal coverage and savings in operational costs due to the requirement of fewer release sites and field staff.
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
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.
‘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.
EPA Grants First Permit to Test Genetically Modified Mosquitoes
11436Adam Allington, Bloomberg Law, 2020-05-01 14:05:51.
British biotech company Oxitec Ltd was granted an experimental use permit to release a genetically engineered type of the mosquito species Aedes aegypti, which is a known vector of Zika virus and viruses that cause yellow fever and dengue fever, the Environmental Protection Agency office of Chemical Safety and Pollution announced.
EPA Approves Experimental Use Permit to Test Innovative Biopesticide Tool to Better Protect Public Health
11434EPA, EPA, 2020-05-01 14:02:09.
Today, after extensive evaluation of the best available science and public input, the U.S. Environmental Protection Agency (EPA) has granted an experimental use permit (EUP) to Oxitec Ltd. to field test the use of genetically engineered Aedes aegypti mosquitoes as a way to reduce mosquito populations to protect public health from mosquito-borne illnesses.
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.
Mosquito-Borne Diseases Emergence/Resurgence and How to Effectively Control It Biologically
12383H. Dahmana and O. Mediannikov, Pathogens, 9:26. 2020-04-23 17:49:22.
Deadly pathogens and parasites are transmitted by vectors and the mosquito is considered the most threatening vector in public health, transmitting these pathogens to humans and animals. We are currently witnessing the emergence/resurgence in new regions/populations of the most important mosquito-borne diseases, such as arboviruses and malaria. This resurgence may be the consequence of numerous complex parameters, but the major cause remains the mismanagement of insecticide use and the emergence of resistance. Biological control programmes have rendered promising results but several highly effective techniques, such as genetic manipulation, remain insufficiently considered as a control mechanism. Currently, new strategies based on attractive toxic sugar baits and new agents, such as Wolbachia and Asaia, are being intensively studied for potential use as alternatives to chemicals. Research into new insecticides, Insect Growth Regulators, and repellent compounds is pressing, and the improvement of biological strategies may provide key solutions to prevent outbreaks, decrease the danger to at-risk populations, and mitigate resistance.
Efficient production of male Wolbachia-infected Aedes aegypti mosquitoes enables large-scale suppression of wild populations
22639J. E. Crawford, D. W. Clarke, V. Criswell, M. Desnoyer, D. Cornel, B. Deegan, K. Gong, K. C. Hopkins, P. Howell, et al., Nature Biotechnology, 38:482-492. 2020-04-06 06:19:43.
The range of the mosquito Aedes aegypti continues to expand, putting more than two billion people at risk of arboviral infection. The sterile insect technique (SIT) has been used to successfully combat agricultural pests at large scale, but not mosquitoes, mainly because of challenges with consistent production and distribution of high-quality male mosquitoes. We describe automated processes to rear and release millions of competitive, sterile male Wolbachia-infected mosquitoes, and use of these males in a large-scale suppression trial in Fresno County, California. In 2018, we released 14.4 million males across three replicate neighborhoods encompassing 293 hectares. At peak mosquito season, the number of female mosquitoes was 95.5% lower (95% CI, 93.6–96.9) in release areas compared to non-release areas, with the most geographically isolated neighborhood reaching a 99% reduction. This work demonstrates the high efficacy of mosquito SIT in an area ninefold larger than in previous similar trials, supporting the potential of this approach in public health and nuisance-mosquito eradication programs.
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.
Synthetically engineered mosquitos could neutralize dengue virus infection
6943L. Woolfe, Biotechniques, 2020-01-22 15:59:46.
Dengue virus infection can be severe and life threatening. New research has developed an improved approach to controlling this deadly infection.
Mosquitoes genetically modified to combat dengue
6740Downtoearth, Down To Earth, 2020-01-20 20:22:34.
For the first time mosquitoes have been engineered to fight all 4 known types of dengue
Genetically Modified Mosquitos Neutralize Dengue Virus
6737N. P. Dyal, Infectious Disease Advisor, 2020-01-20 18:53:09.
Researchers at the University of California San Diego have identified a target gene in mosquitos that renders the insects completely refractory to all 4 serotypes of the dengue virus and thus, incapable of transmitting the virus to humans, according to study results published in PLoS Pathogens
Genetically modified mosquitoes resist all dengue viruses, researchers find
6709B. Burton, C|NET, 2020-01-17 18:24:25.
This new kind of mosquito can't spread any form of the deadly disease.
Genetically engineered mosquitoes resist spreading any form of dengue
6734K. Servick, Science, 2020-01-16 18:50:53.
Recover from dengue once, and you’re not necessarily free and clear. The mosquito-borne disease marked by fever, rash, and debilitating pain results from any of four genetically distinct versions of the dengue virus. Previously infected people who get hit with a second of these “serotypes” can face more severe, even life-threatening symptoms. Now, by endowing a line of mosquitoes with an antibody against the virus, researchers have for the first time made insects that—at least in lab tests—appear unable to spread any form of the disease. In theory, these mosquitoes could be released into the wild to suppress the circulation of the virus.
Genetically engineered mosquitoes halt Dengue spread
6730L. Thomas, New Medical Life Sciences, 2020-01-16 18:44:27.
A new study published in the journal PLOS Pathogens in January 2020 reports the development of mosquitoes that have been genetically modified to resist infection by several types of the dengue virus. This is the first time ever that all types of the virus have been targeted by the engineering of the mosquito DNA. Covering all virus types is essential to achieve proper disease control.
Researchers Genetically Modify First Batch Of Mosquitoes Resistant To All Four Types Of Dengue
6725M. Dapcevich, IFL Science, 2020-01-16 18:39:05.
An international team of researchers have synthetically engineered a breed of mosquitos that are resistant to all four types of the dengue virus for the first time, a feat they say may someday suppress the disease and stop its transmission to humans.
Genetically engineered mosquitoes are immune to all strains of dengue virus for first time
6719G. Weule, ABC News Online, 2020-01-16 18:34:13.
Locked in a secure lab near Melbourne is the newest addition in the fight against dengue: genetically engineered mosquitoes that are resistant to all strains of the potentially deadly virus.
Mosquitoes resistant to all types of dengue virus engineered
6714N. Lavars, New Atlas, 2020-01-16 18:28:54.
Last year, scientists at Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) made a big breakthrough, engineering mosquitoes that break the chain of Zika virus transmission. But they did so with multiple targets in mind, with the mosquito in question, Aedes aegypti, also acting as the number one disease vector for the dengue virus. The researchers have now added this arrow to the quiver of their genetically-modified mosquitoes, with hopes of tackling what they see as a global epidemic.
Broad dengue neutralization in mosquitoes expressing an engineered antibody
6706A. Buchman, S. Gamez, M. Li, I. Antoshechkin, H.-H. Li, H.-W. Wang, C.-H. Chen, M. J. Klein, J.-B. Duchemin, J. E. Crowe, Jr., P. N. Paradkar and O. S. Akbari, PLOS Pathogens, 16:e1008103. 2020-01-16 18:18:14.
Author summary With limited success of traditional vector control methods to curb dengue infections and more than half of the world’s population still at risk, there is a need for novel strategies to reduce its impact on public health. Recent advances in genetic technologies has allowed for precise modifications of mosquito genome to make them resistant to infections, thus breaking the transmission cycle. Here we generated engineered Ae. aegypti mosquitoes efficiently expressing a DENV-targeting single-chain variable fragment (scFv) derived from a previously characterized broadly neutralizing human antibody, which blocked infection and transmission in these mosquitoes. To our knowledge, this is the first example of an engineered transgene capable of rendering Ae. aegypti mosquitoes 100% refractory to all four serotypes of DENV. The engineered mosquitoes, in future, could easily be paired with a gene drive, capable of spreading the transgene throughout wild disease-transmitting mosquito populations and preventing further DENV transmission. Since a number of diverse and well-characterized antibodies exist against other arboviruses (eg chikungunya and Zika, this work also provides a proof-of-concept principle for developing similar genetic strategies for reducing the impact of these arboviruses.
Development of a confinable gene drive system in the human disease vector Aedes aegypti
6697M. Li, T. Yang, N. P. Kandul, M. Bui, S. Gamez, R. Raban, J. Bennett, H. M. Sánchez C, G. C. Lanzaro, H. Schmidt, Y. Lee, J. M. Marshall and O. S. Akbari, eLife, 9:e51701. 2020-01-16 18:07:34.
Aedes aegypti is the principal mosquito vector for many arboviruses that increasingly infect millions of people every year. With an escalating burden of infections and the relative failure of traditional control methods, the development of innovative control measures has become of paramount importance. The use of gene drives has sparked significant enthusiasm for genetic control of mosquitoes; however, no such system has been developed in Ae. aegypti. To fill this void, here we develop several CRISPR-based split gene drives for use in this vector. With cleavage rates up to 100% and transmission rates as high as 94%, mathematical models predict that these systems could spread anti-pathogen effector genes into wild populations in a safe, confinable and reversible manner appropriate for field trials and effective for controlling disease. These findings could expedite the development of effector-linked gene drives that could safely control wild populations of Ae. aegypti to combat local pathogen transmission.
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.
Antiviral effectors and gene drive strategies for mosquito population suppression or replacement to mitigate arbovirus transmission by Aedes aegypti
6634A. E. Williams, A. W. E. Franz, W. R. Reid and K. E. Olson, Insects, 11:1-18. 2020-01-12 20:05:33.
The mosquito vector Aedes aegypti transmits arthropod-borne viruses (arboviruses) of medical importance, including Zika, dengue, and yellow fever viruses. Controlling mosquito populations remains the method of choice to prevent disease transmission. Novel mosquito control strategies based on genetically manipulating mosquitoes are being developed as additional tools to combat arbovirus transmission. Genetic control of mosquitoes includes two basic strategies: population suppression and population replacement. The former aims to eliminate mosquito populations while the latter aims to replace wild populations with engineered, pathogen-resistant mosquitoes. In this review, we outline suppression strategies being applied in the field, as well as current antiviral effector genes that have been characterized and expressed in transgenic Ae. aegypti for population replacement. We discuss cutting-edge gene drive technologies that can be used to enhance the inheritance of effector genes, while highlighting the challenges and opportunities associated with gene drives. Finally, we present currently available models that can estimate mosquito release numbers and time to transgene fixation for several gene drive systems. Based on the recent advances in genetic engineering, we anticipate that antiviral transgenic Ae. aegypti exhibiting gene drive will soon emerge; however, close monitoring in simulated field conditions will be required to demonstrate the efficacy and utility of such transgenic mosquitoes.
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.
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.
MGDrivE: A modular simulation framework for the spread of gene drives through spatially-explicit mosquito populations
3941Sánchez C, HMW, Sean L.; Bennett, Jared B.; Marshall, John M., Methods in Ecology and Evolution, 10:1-24. 2019-01-19 00:00:00.
Malaria, dengue, Zika, and other mosquito-borne diseases continue to pose a major global health burden through much of the world, despite the widespread distribution of insecticide-based tools and antimalarial drugs. The advent of CRISPR/Cas9-based gene editing and its demonstrated ability to streamline the development of gene drive systems has reignited interest in the application of this technology to the control of mosquitoes and the diseases they transmit. The versatility of this technology has enabled a wide range of gene drive architectures to be realized, creating a need for their population-level and spatial dynamics to be explored. 2.We present MGDrivE (Mosquito Gene Drive Explorer): a simulation framework designed to investigate the population dynamics of a variety of gene drive architectures and their spread through spatially-explicit mosquito populations. A key strength of the MGDrivE framework is its modularity: a) a genetic inheritance module accommodates the dynamics of gene drive systems displaying userdefined inheritance patterns, b) a population dynamic module accommodates the life history of a variety of mosquito disease vectors and insect agricultural pests, and c) a landscape module generates the metapopulation model by which insect populations are connected via migration over space. 3.Example MGDrivE simulations are presented to demonstrate the application of the framework to CRISPR/Cas9-based homing gene drive for: a) driving a disease-refractory gene into a population (i.e. population replacement), and b) disrupting a gene required for female fertility (i.e. population suppression), incorporating homing-resistant alleles in both cases. Further documentation and use examples are provided at the project's Github repository. 4.MGDrivE is an open-source R package freely available on CRAN. We intend the package to provide a flexible tool capable of modeling novel inheritance-modifying constructs as they are proposed and become available. The field of gene drive is moving very quickly, and we welcome suggestions for future development.
Engineered resistance to Zika virus in transgenic Aedes aegypti expressing a polycistronic cluster of synthetic small RNAs
3895Buchman, AG, S.; Li, M.; Antoshechkin, I.; Li, H. H.; Wang, H. W.; Chen, C. H.; Klein, M. J.; Duchemin, J. B.; Paradkar, P. N.; Akbari, O. S., Proceedings of the National Academy of Sciences of the United States of America, 116:3656-3661. 2019-01-13 00:00:00.
Recent Zika virus (ZIKV) outbreaks have highlighted the necessity for development of novel vector control strategies to combat arboviral transmission, including genetic versions of the sterile insect technique, artificial infection with Wolbachia to reduce population size and/or vectoring competency, and gene drive-based methods. Here, we describe the development of mosquitoes synthetically engineered to impede vector competence to ZIKV. We demonstrate that a polycistronic cluster of engineered synthetic small RNAs targeting ZIKV is expressed and fully processed in Aedes aegypti, ensuring the formation of mature synthetic small RNAs in the midgut where ZIKV resides in the early stages of infection. Critically, we demonstrate that engineered Ae. aegypti mosquitoes harboring the anti-ZIKV transgene have significantly reduced viral infection, dissemination, and transmission rates of ZIKV. Taken together, these compelling results provide a promising path forward for development of effective genetic-based ZIKV control strategies, which could potentially be extended to curtail other arboviruses.
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.
Advances in vector control science: Rear-and-release strategies show promise… but don’t forget the basics
4065Ritchie, SAJ, B. J., Journal of Infectious Diseases, 215:S103-S108. 2017-01-03 00:00:00.
Both chikungunya and Zika viruses have recently swept from Africa across the Pacific to the Americas, causing major outbreaks of disease in humans. In the meantime, dengue epidemics continue throughout the tropics. Traditional vector control programs based on strategies from 1950s and 1960s have been relatively ineffective in combating recent epidemics. In response, new methods involving the rearing and releasing of large numbers of mosquitoes to eliminate or modify local Aedes populations are being developed, with several currently conducting field releases in high-risk countries. These advances, include the release of Wolbachia-infected Aedes aegypti and Aedes albopictus, for either its virus-blocking capabilities, sterilization by cytoplasmic incompatibility, or both; the release of Aedes carrying dominant lethal genes, such as the OX513A strain of A. aegypti; and other emerging techniques, such as advancing gene-drive technologies, are summarized, as well as current stages of development and primary operational and regulatory hurdles. Although these technologies show great promise, none are ready for widespread rollout for cities of millions of people. Thus, efforts should be made to avoid methods such as space sprays that have failed and improve existing technologies to increase their efficacy.
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
Cheating evolution: engineering gene drives to manipulate the fate of wild populations
4083Champer, JB, A.; Akbari, O. S., Nature Reviews Genetics, 17:146-159. 2016-01-21 00:00:00.
Engineered gene drives - the process of stimulating the biased inheritance of specific genes - have the potential to enable the spread of desirable genes throughout wild populations or to suppress harmful species, and may be particularly useful for the control of vector-borne diseases such as malaria. Although several types of selfish genetic elements exist in nature, few have been successfully engineered in the laboratory thus far. With the discovery of RNA-guided CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR-associated 9) nucleases, which can be utilized to create, streamline and improve synthetic gene drives, this is rapidly changing. Here, we discuss the different types of engineered gene drives and their potential applications, as well as current policies regarding the safety and regulation of gene drives for the manipulation of wild populations.
Back to the future: the sterile insect technique against mosquito disease vectors
25916R. S. Lees, J. R. L. Gilles, J. Hendrichs, M. J. B. Vreysen and K. Bourtzis, Current Opinion in Insect Science, 10:156-162. 2015-06-03 13:09:41.
With the global burden of mosquito-borne diseases increasing, and some conventional vector control tools losing effectiveness, the sterile insect technique (SIT) is a potential new tool in the arsenal. Equipment and protocols have been developed and validated for efficient mass-rearing, irradiation and release of Aedines and Anophelines that could be useful for several control approaches. Assessment of male quality is becoming more sophisticated, and several groups are well advanced in pilot site selection and population surveillance. It will not be long before SIT feasibility has been evaluated in various settings. Until perfect sexing mechanisms exist, combination of Wolbachia-induced phenotypes, such as cytoplasmic incompatibility and pathogen interference, and irradiation may prove to be the safest solution for population suppression.
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.
Requirements for effective malaria control with homing endonuclease genes
4203Deredec, AG, H. C. J.; Burt, A., Proceedings of the National Academy of Sciences of the United States of America, 108:e874-e880. 2011-01-21 00:00:00.
Malaria continues to impose a substantial burden on human health. We have previously proposed that biological approaches to control the mosquito vector of disease could be developed using homing endonuclease genes (HEGs), a class of selfish or parasitic gene that exists naturally in many microbes. Recent lab studies have demonstrated that HEGs can function in mosquitoes. We constructed and analyzed a model of mosquito population genetics and malaria epidemiology to determine how well HEGs need to function in order to have a significant effect on the burden of disease. Our model, combined with currently available data, indicates that populations of Anopheles gambiae could be eliminated by releasing 2-3 HEGs targeting female fertility genes, or a driving-Y chromosome that is transmitted to 75-96% of progeny. Combinations of fertility-targeting HEGs and Y drive may also be effective. It is possible to eliminate the disease without eliminating the vector, but the parameter space producing this outcome appears to be small. HEGs causing a quantitative reduction in adult survival can be more effective than those targeting female fertility, but the selection coefficients that need to be imposed are still large, unless many HEGs are to be released. Simulations show that HEG-based strategies can be effective over socially relevant time frames. Important limiting assumptions of the models are that there is only a single vector species, and we model a homogeneous population, not a landscape. Nevertheless, we conclude that HEG-based approaches could have a transformational effect on malaria control efforts.
Wolbachia and cytoplasmic incompatibility in mosquitoes
4300Sinkins, SP, Insect Biochemistry and Molecular Biology, 34:723-729. 2004-01-18 00:00:00.
Wolbachia are maternally inherited bacteria that induce cytoplasmic incompatibility in mosquitoes, and are able to use these patterns of sterility to spread themselves through populations. For this reason they have been proposed as a gene drive system for mosquito genetic replacement, as well as for the reduction of population size or for modulating population age structure in order to reduce disease transmission. Here, recent progress in the study of mosquito Wolbachia is reviewed. We now have much more comprehensive estimates of the parameters that can affect the spread of Wolbachia through natural populations from low starting frequencies. and for waves of spread to be maintained in the face of partial barriers to gene flow. In Aedes albopictits these dynamics are extremely favourable, with very high maternal transmission fidelity and levels of incompatibility recorded. Correspondence between measurements taken in the lab and field is much better than in the Drosophila simulans model system. Important research goals are also discussed, including Wolbachia transformation, interspecific transfer and the elucidation of the mechanisms of incompatibility and rescue; all will be aided by a wealth of new Wolbachia genome information. (C) 2004 Elsevier Ltd. All rights reserved.
Mariner transposition and transformation of the yellow fever mosquito, Aedes aegypti
6256C. J. Coates, N. Jasinskiene, L. Miyashiro and A. A. James, Proceedings of the National Academy of Sciences of the United States of America, 95:3748-3751. 1998-03-07 19:31:51.
The mariner transposable element is capable of interplasmid transposition in the embryonic soma of the yellow fever mosquito, Aedes aegypti. To determine if this demonstrated mobility could be utilized to genetically transform the mosquito, a modified mariner element marked with a wild type allele of the Drosophila melanogaster cinnabar gene was microinjected into embryos of a kynurenine hydroxylase-deficient, white-eyed recipient strain. Three of 69 fertile male founders resulting from the microinjected embryos produced families with colored-eyed progeny individuals, a transformation rate of 4%. The transgene-mediated complementation of eve color was observed to segregate in a Mendelian manner, although one insertion segregates with the recessive allele (female-determining) of the sex-determining locus, and a separate insertion is homozygous lethal. Molecular analysis of selected transformed families demonstrated that a single complete copy of the construct had integrated independently in each case acid that it had done so in a transposase-mediated manner. The availability of a mariner transformation system greatly enhances our ability to study and manipulate this important vector species.
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.
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