Scholarly Literature
This is an aggregation of scholarly literature from peer-reviewed journals, bioRxiv , medRxiv and arXiv preprint servers focused on natural and engineered selfish genetic elements and genetic biocontrol. New citations are added as they appear. This content is intended for anyone interested in the scholarly literature on gene drive and genetic biocontrol.
Experimental Test of Evolutionary Safety of a CRISPR-Cas9 Gene-Drive Element
34958Michael S Overton, Sean E Guy, Xingsen Chen, et al., bioRxiv, 2025-07-08 13:24:10.
CRISPR-Cas9 gene drives (CCGDs) are powerful tools for genetic control of wild populations, with applications from disease eradication to species conservation. However, Cas9 alone and in a complex with gRNA can cause double-stranded DNA breaks at off-target sites, which could increase the mutational load and lead to unintended loss-of-heterozygosity (LOH) events. These undesired effects raise potential concerns about the long-term evolutionary safety of CCGDs, but the magnitude of these effects is unknown. To measure how the presence of a CCGD or a Cas9 alone in the genome affects the rates of LOH events and de novo mutations, we carried out a mutation accumulation experiment in yeast Saccharomyces cerevisiae. We found no detectable effects on the genome-wide rates of mutations or LOH events. Our power calculations suggest that CCGD or Cas9 affect these rates by less than 30%, which is much less than natural variation for these traits in yeast. A more detailed examination shows that CCGD or Cas9 may alter the lengths and genomic distributions of LOH events, but the statistical support for these effects is weak. Thus, our results demonstrate that CCGDs impose at most a weak additional mutational burden in the yeast model. Although mutagenic effects of gene drives need to be further evaluated in other systems, our results add credence to the proposition that the evolutionary risks posed by well designed gene drives are likely acceptable.
Synthetically Assisted Conservation and the Application of Emerging Biological Technologies for the Protection of Biodiversity
34956Jedediah F. Brodie, Amanda Emmel, Blake Wiedenheft, et al., Conservation Letters, 8. 2025-07-08 13:20:29.
New tools of synthetic biology that enable precise manipulation of genomes, metabolic pathways, and ecosystems present new opportunities, risks, ethical dilemmas, and responsibilities for stewards of biodiversity. We argue that the risks and benefits of synthetic biology for use in biodiversity conservation, which we term “synthetically assisted conservation,” can be better understood, evaluated, and regulated by precisely defining the techniques in relation to well-established and regulated conservation frameworks: conservation translocation and integrated pest management. Synthetically assisted conservation translocation could include the release of genetically modified organisms for in situ conservation of genes or restoration of ecological functions, while a synthetically assisted application of integrated pest management could involve using genetic modifications propagated through gene drives to remove invasive species. Contextualizing the range of techniques as expansions of these frameworks clarifies how new approaches may impact conservation, facilitating risk assessment and responsible implementation. Decision-making may be informed by existing policy guidance in accordance with national and international regulations on conservation translocation and integrated pest management. Nevertheless, additional policy and evaluative guidelines are needed to keep pace with rapid technological growth and novel issues such as the release of genes (e.g., in pollen or marine-dispersed gametes) separate from live organisms.
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.
Extended time to maturity in Anopheles coluzzii: Implications of late egg hatch for vector control and transgene fitness
34947Emmanuel C. Ottih, Joe M. Roberts, Toby J. A. Bruce, Frédéric Tripet, Medical and Veterinary Entomology, 2025-06-24 10:11:30.
Maintaining fitness is an important consideration when mosquitoes are mass-reared for the deployment of genetic interventions that are designed to suppress populations because released mosquitoes need to compete with wild-type mosquitoes. Late-hatching mosquitoes are more suitable for transportation to remote field sites. Here, we investigated the fitness of late-hatching phenotypes in Anopheles coluzzii. Selected lines of the VK strain (from Burkina Faso) were created through bidirectional selection for early and late hatching, over 20 generations. These were compared with each other and the established Mopti reference strain from Mali, reared in the lab for >16 years. Significant differences in life-history traits were found between Mopti and VK strains but few differences were found between the selected VK lines. Considering that late-hatching VK lines showed no evidence of fitness costs, our results suggest that the late selected VK lines, which start hatching after 4 days, are an alternative option for egg shipment for mass mosquito releases over the well-established Mopti that hatches within 2 days and has lower adult survival.
A male-drive female-sterile system for the self-limited control of the malaria mosquito Anopheles gambiae
34945Anna Strampelli, Katie Willis, Hannah Robyn Gulliford, et al., bioRxiv, 2025-06-24 10:02:54.
The use of insecticides and antimalarial drugs has been crucial in reducing the mortality and morbidity associated with malaria. However, since 2015, several challenges, including the development of resistance to these insecticides and treatments and changes in mosquito behaviour, have hindered the progress in fighting the disease. As a result, there is a pressing need for new tools to control malaria, including the potential use of genetically modified mosquitoes (GMMs) in the field. Various genetic strategies for vector control are currently being explored, ranging from self-sustaining GMMs with unrestricted geographic and temporal spread to self-limiting alternatives. Here, we propose a self-limiting gene drive strategy called Male Drive Female Sterile (MDFS) targeting Anopheles gambiae, a major malaria vector. The MDFS genetic construct causes dominant sterility in females, while transgenic males remain fertile, allowing them to transmit the female sterility trait at super-Mendelian rates. Laboratory studies have shown that repeated releases of MDFS can lead to the elimination of caged mosquito populations. Based on these findings, modelling suggests that MDFS could be a highly effective and self-limiting strategy for suppressing wild malaria mosquito populations.
The B Chromosome of Pseudococcus viburni: A Selfish Chromosome that Exploits Whole-Genome Meiotic Drive
34939Isabelle M Vea, Andrés G de la Filia, Kamil S Jaron, Scott E J Barlow, Marion Herbette, Andrew J Mongue, Ross Nelson, Francisco J Ruiz-Ruano, Laura Ross, Genome Biology and Evolution, 17. 2025-06-24 08:56:02.
Meiosis is generally a fair process: each chromosome has a 50% chance of being included into each gamete. However, meiosis can become aberrant with some chromosomes having a higher chance of making it into gametes than others. Yet, why and how such systems evolve remains unclear. Here, we study the unusual reproductive genetics of mealybugs, where only maternal-origin chromosomes are included in gametes during male meiosis, while paternal chromosomes are eliminated. One species—Pseudococcus viburni—has a segregating B chromosome that drives by escaping paternal genome elimination. We present whole genome and gene expression data from lines with and without B chromosomes. We identify B-linked sequences including 204 protein-coding genes and a satellite repeat that makes up a significant proportion of the chromosome. The few paralogs between the B and the core genome are distributed throughout the genome, arguing against a simple, or at least recent, chromosomal duplication of one of the autosomes to create the B. We do, however, find one 373 kb region containing 146 genes that appears to be a recent translocation. Finally, we show that while many B-linked genes are expressed during meiosis, most of these are encoded on the recently translocated region. Only a small number of B-exclusive genes are expressed during meiosis. Of these, only one was overexpressed during male meiosis, which is when the drive occurs: an acetyltransferase involved in H3K56Ac, which has a putative role in meiosis and is, therefore, a promising candidate for further studies.
Changes in the frequency of facultative endosymbionts in insect populations: overview and applications
34922Hoffmann, Ary A.; Cooper, Brandon S., Entomologia Generalis, 45:351-368. 2025-06-23 14:41:27.
Many insect endosymbionts are facultative from the host perspective, and their population frequencies across time and space will depend on their transmission fidelity and effects on host fitness. These effects and transmission rates in turn depend on the environmental and host genetic contexts where the endosymbionts occur. Endosymbionts like Wolbachia and Cardinium affect host reproduction to produce transient or persistent presence/absence polymorphisms, while other endosymbionts like Regiella and Hamiltonella persist through providing host fitness benefits and transmitting horizontally. Evolutionary changes in hosts and endosymbionts affect these impacts and endosymbiont polymorphisms in host populations and host sexes. We review this diversity of endosymbiont-host interactions and their influence on the usefulness of endosymbionts for applied strategies. Current strategies focus on endosymbionts driving useful traits to fixation (particularly Wolbachia suppression of arbovirus transmission by mosquitoes) or endosymbionts suppressing populations due to infected males sterilising females. Transinfected endosymbionts sourced from one species and microinjected into another have proven effective in these Wolbachia-mosquito strategies. Novel strategies involving transinfected Rickettsiella, Regiella and Wolbachia may decrease the impacts of pest invertebrates by suppressing pest numbers, reducing the capacity of vector hosts to transmit plant viral diseases or bolstering the effectiveness of natural enemies. Because many endosymbionts are already present in the environment, their applied use raises fewer safety concerns when compared to genetic modification, as supported by more than 13 years of field experiences with Wolbachia in mosquitoes that have not raised major concerns.
Mozzie: a computationally efficient simulator for the spatio-temporal modelling of mosquitoes
34916Wilkins et al., Journal of Open Source Software, 10. 2025-06-16 13:04:27.
Mozzie enables simulation of the lifecycle and spatial spread of mosquitoes. Mozzie can be used to assess risks associated with disease-control strategies at local, regional or continental scales. Most particularly, strategies involving genetic alterations of mosquitoes to eliminate malaria, are of prime interest. More technically, Mozzie simulates a population-dynamics model that uses differential equations or delay differential equations (Bohner et al., 2018; El-Hachem & Beeton, 2024) to describe the spread and persistence of mosquitoes that may be genetically altered. Genetic alterations are flexibly modelled: these can involve any number of alleles; Mendelian or non-Mendelian inheritance, including gene drives; they can be self-limiting or self-sustaining; and can include the emergence of resistant allelles. The model allows simulation of 𝑁 mosquito species. It incorporates mate-choice, hybridisation and intra-specific competition that occur within complexes of mosquito species (Beeton et al., 2020). This fills a gap that currently exists among similar models, allowing researchers to assess potential transfer of the genetic alterations between (sub-)species. Mozzie supports spatial and temporal variations in lifecyle parameters, and local diffusion andwind-assisted, long range, advection. For example, wind patterns and the capacity of the landscape to support mosquitoes can vary spatially and temporally, reflecting daily variations, seasonality, and local conditions. Conversely, Mozzie does not contain human agents, nor does it consider the effect of genetic control strategies on the prevalence of pathogens such as the malaria parasite, among human or animal populations. Mozzie has been used by the authors to simulate the spread across sub-Saharan Africa of a theoretical, population-modifying, gene drive in Anopheles gambiae s.s. and Anopheles coluzzii (Beeton et al., 2022) (that paper also describes the mathematics of a particular mosquito lifecycle model that is contained in Mozzie). It has also been used to predict the spread of Target Malaria’s Paternal Male Bias construct (Galizi et al., 2014) following a proposed field-release of genetically modified Anopheles coluzzi male mosquitoes in Burkina Faso (Hosack et al., 2023).
Modelling and sensitivity analysis to control dengue through inclusion of genetically modified hybrid mosquitoes
34907Wasim, T., Ismaeel, T., Naseem, A., Abdeljawad, T., & Alqudah, M. A., Mathematical and Computer Modelling of Dynamical Systems, 31. 2025-06-15 18:50:47.
Dengue fever, an ancient yet persistent global health threat transmitted by mosquitoes, remains difficult to control. Recent advances propose genetically modified hybrid mosquitoes as a novel intervention. This study focuses on two primary control strategies: the Sterile Insect Technique (SIT) and genetic sterilization. SIT involves releasing sterile male mosquitoes to reduce populations through unsuccessful mating, while genetic sterilization targets mosquito reproduction or virus transmission capabilities. In our proposed model, modified mosquitoes are included in the susceptible vector compartment, denoted as ℧𝑚. Diagnosis and treatment are modeled with parameters 𝑑1 and 𝑑2. Field and laboratory studies suggest these methods effectively reduce mosquito populations and dengue incidence. A mathematical model is developed to study this strategy’s impact, incorporating the basic reproduction number 𝑅0 and equilibrium analysis. Numerical methods are used to assess system stability and compute sensitivity indices 𝒲ℋ𝜉, ultimately demonstrating the potential for effective dengue control.
Influence of genetic factors of humans, mosquitoes and parasites, on the evolution of Plasmodium falciparum infections, malaria transmission and genetic control methods: a review of the literature
34903Nikiema, S., Soulama, I., Ampofo, G.D. et al., BMC Medical Genomics, 18. 2025-06-06 08:52:12.
Despite significant progress, malaria remains a public health problem in many regions, particularly in sub-Saharan Africa. This situation is partly explained by the mosquito’s resistance to insecticides and the emergence of parasite resistance to antimalarial drugs. Indeed, in spite of the various vectors’ controls, insecticide resistance emerges from multi-generational selection and poses worldwide concern. In parallel, artemisinin resistance unfortunately emerged independently in multiple countries in eastern Africa. Since 2014, artemisinin resistance has been observed in 6 countries in Africa and, more concerningly, the evidence from longitudinal molecular surveys in these countries suggests that it is spreading. While phenotypic evidence of treatment failure is still limited, the increasing reports of validated artemisinin resistance mutations are alarming. Unlike the emergence of artemisinin resistance in South-East Asia, our understanding of the genetic determinants of artemisinin resistance and our ability to sequence and map the spread of resistance are significantly greater. In addition to mosquito and parasite genetics affecting malaria evolution, many human individual variants have been identified that are associated with malaria protection, but the most important of all relates to the structure or function of red blood cells, the classical polymorphisms that causes sickle cell trait, α-thalassaemia, G6PD deficiency, and the major red cell blood group variants. In that biological complex context, there is a need to characterize the various genetic factors in Plasmodium falciparum, humans and mosquitoes that are potentially associated with resistance to antimalarial drugs and insecticides, and their involvement in the evolution, severity and transmission of malaria. In this direction, A comprehensive literature review was conducted to capture the objectives highlighted above. The advances in genomic surveillance and emerging genetic control strategies, such as gene drive technology were also considered in this review. We used search engines such as PubMed and Google scholar to retrieve articles useful to the objective of this paper and information on the knowledge of genetic factors and methods that contributed to malaria control were synthesized.
Conflicting Kinesin-14s in a single chromosomal drive haplotype
34899Meghan J Brady, Anjali Gupta, Jonathan I Gent, et al., Genetics, 2025-06-06 08:37:38.
In maize, there are 2 meiotic drive systems that target large heterochromatic knobs composed of tandem repeats known as knob180 and TR-1. The first meiotic drive haplotype, abnormal chromosome 10 (Ab10) confers strong meiotic drive (∼75% transmission as a heterozygote) and encodes 2 kinesins: KINDR, which associates with knob180 repeats, and TRKIN, which associates with TR-1 repeats. Prior data show that meiotic drive is conferred primarily by the KINDR/knob180 system while the TRKIN/TR-1 system seems to have little or no role, making it unclear why Trkin has been maintained in Ab10 haplotypes. The second meiotic drive haplotype, K10L2, confers a low level of meiotic drive (∼51–52%) and only encodes the TRKIN/TR-1 system. Here, we used long-read sequencing to assemble the K10L2 haplotype and showed that it has strong homology to an internal portion of the Ab10 haplotype. We also carried out CRISPR mutagenesis to test the role of Trkin on Ab10 and K10L2. The data indicate that the Trkin gene on Ab10 does not improve drive or fitness but instead has a weak deleterious effect when paired with a normal chromosome 10. The deleterious effect is more severe when Ab10 is paired with K10L2: in this context, functional Trkin on either chromosome nearly abolishes Ab10 drive. Mathematical modeling based on the empirical data suggests that Trkin is unlikely to persist on Ab10. We conclude that Trkin either confers an advantage to Ab10 in untested circumstances or that it is in the process of being purged from the Ab10 population.
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.
Intrinsically weak sex chromosome drive through sequential asymmetric meiosis
34889Xuefeng Meng, Yukiko M. Yamashita, Science Advances, 11. 2025-06-02 19:06:59.
Meiotic drivers are selfish genetic elements that bias their own transmission, violating Mendel’s Law of Equal Segregation. It has long been recognized that sex chromosome–linked drivers present a paradox: Their success in transmission can severely distort populations’ sex ratio and lead to extinction. This paradox is typically solved by the presence of suppressors or fitness costs associated with the driver, limiting the propagation of the driver. Here, we show that Stellate (Ste) in Drosophila melanogaster represents a novel class of X chromosome–linked driver that operates with an inherent mechanism that weakens its drive strength. Ste protein asymmetrically segregates into Y-bearing cells during meiosis I, subsequently causing their death. Unexpectedly, Ste segregates asymmetrically again during meiosis II, sparing half of the Y-bearing spermatids from Ste-induced defects, thereby weakening the drive strength. Our findings reveal a mechanism by which sex chromosome drivers avoid suicidal success.
Efficient CRISPR-Cas9-mediated genome editing of the cane toad (Rhinella marina)
34887Michael Clark, Alexander T. Funk, Alex Paporakis, et al., bioRxiv, 2025-06-02 19:02:13.
Invasive species inflict major ecological, economic, social, and cultural harm worldwide, highlighting the urgent need for innovative and effective control strategies. Genome editing offers exciting possibilities for creating highly targeted control methods for invasive species. Here, we demonstrate CRISPR-Cas9 genome editing in the cane toad (Rhinella marina), one of Australia’s most notorious invasive species, by targeting the tyrosinase gene to produce albino phenotypes that provide clear visual markers for assessing editing efficiency. Microinjection of Cas9 protein and guide RNAs into one-cell zygotes resulted in 87.6% of mosaic larvae displaying nearly complete albinism, with 2.3% exhibiting complete albinism. For completely albino individuals, genomic analysis confirmed predominantly frameshift mutations or large deletions at the target site, with no wild-type alleles detected. Germline transmission rates reflected the extent of albinism in the mosaic adult, where we achieved maternal germline transmission rates of almost 100%. This technology, representing the first application of CRISPR-Cas9 in the Bufonidae family, opens possibilities for exploring both basic research questions and strategies for population control.
An animal toxin-antidote system kills cells by creating a novel cation channel
34881Caro L, Wei AD, Thomas CA, Posch G, Uremis A, Franzi MC, et al., PLoS Biology, 23. 2025-06-02 18:36:53.
Toxin-antidote systems are selfish genetic elements composed of a linked toxin and antidote. The peel-1 zeel-1 toxin-antidote system in C. elegans consists of a transmembrane toxin protein PEEL-1 which acts cell autonomously to kill cells. Here we investigate the molecular mechanism of PEEL-1 toxicity. We find that PEEL-1 requires a small membrane protein, PMPL-1, for toxicity. Together, PEEL-1 and PMPL-1 are sufficient for toxicity in a heterologous system, HEK293T cells, and cause cell swelling and increased cell permeability to monovalent cations. Using purified proteins, we show that PEEL-1 and PMPL-1 allow ion flux through lipid bilayers and generate currents which resemble ion channel gating. Our work suggests that PEEL-1 kills cells by co-opting PMPL-1 and creating a cation channel.
Applying the Protective Precautionary Principle to the Ethical Use of Gene Drive Technology for Anopheles gambiae Suppression in Malaria Control
34879Nucharee Wongsamut, Journal of Applied Animal Ethics Research, 2025-06-02 18:16:36.
Malaria contributes to poverty and illness, which further hinder productivity and income generation. Therefore, combating malaria is crucial for breaking the vicious cycle of poverty. Genome editing technologies, such as gene drives designed to suppress Anopheles gambiae mosquito populations, the vector for malaria, have emerged as potential tools in this fight. However, a significant ethical question arises: under what conditions is the use of gene drive technology to suppress Anopheles gambiae mosquito populations justified? This article argues that the Protective Precautionary Principle can serve as a suitable framework for morally assessing such cases. Within this framework, the use of gene drive technology for Anopheles gambiae population suppression would be permissible for laboratory research only. This limited scope minimizes the risk of unforeseen negative consequences, particularly for disadvantaged populations who may have fewer resources to protect themselves from such effects.
The challenge of measuring mosquito flight performance: going beyond sterile insect technique and into transgenic and gene drive-based approaches
35311Paola Najera, Christian E. Ogaugwu, Tyler F. Chan, et al., Open Biology, 15. 2025-06-01 10:32:43.
Invasive insects inflict global costs of more than 70 billion USD annually by destroying crops and spreading disease-causing pathogens. Sterile insect technique (SIT), an insect population control method, involves the irradiation or chemical sterilization of insects to produce sterile males that are mass-released. SIT has proven effective in reducing populations of the Mediterranean fruit fly, Mexican fruit fly and screwworm fly. In the past decade, efforts to improve SIT with transgenic approaches have increased, including the development of potentially highly invasive gene drive transgenes. Determining flight capability is vital to the success of any insect control programme, and various flight assays can be used to analyse insect dispersal, flight behaviour and the mechanics behind flight. However, traditional flight assays such as mark–release–recapture become more challenging with transgenic or gene drive arthropods due to ecological concerns, while assays such as wind tunnels or flight mills/arenas may not capture the full range of flight abilities. This review seeks to cover current flight assays and their limitations as well as the requirements for flight assays to establish comparative flight ability for genetically modified insects to better prioritize strains prior to any potential field-based releases.
Paratransgenesis: Overview, Current Perspectives, and Future Research Needs for Malaria Control
34874Oziegbe, O., Okeke, C.C., Esho, D.O., Springer, Cham., 2025-05-26 21:52:21.
Malaria is an insect-borne disease (IBD) that is responsible for significant human mortality and morbidity globally. Several effective vector and parasite control strategies have been considered to control malaria. However, paratransgenesis is a strategy targeted towards parasite development disruption rather than vector elimination which can potentially address insecticide resistance in mosquitoes. Genetically modified symbionts such as bacteria, fungi, or viruses secrete anti-plasmodial effector molecules that kill or inhibit the development of Plasmodium species without affecting the vector or the microorganism. Various anti-plasmodial effector molecules have been identified such as scorpin, a peptide from scorpion venom that acts by lysing the parasite, enolase- plasminogen interaction peptide (EPIP) which acts by inhibiting midgut invasion, A protein kinase (Akt) that acts by activating innate immune responses, and salivary gland and midgut peptide 1 (SMI) that acts by preventing binding to the parasite surface proteins. For this strategy to be successful, the selected symbiotic microorganism should be easy to culture and genetically manipulate, stable, as well as capable of producing effector molecules with anti-plasmodial activity while colonizing a wide range of the host species. Paratransgenesis presents a promising future for malaria control globally. However, its efficacy and safety as a malaria control strategy should be experimented with in large outdoor settings with more elaborate and collaborative studies carried out to sustain the approach in malaria-endemic countries.
Assessing the population genetic structure and demographic history of Anopheles gambiae and An. arabiensis at island and mainland populations in Uganda: Implications for testing novel malaria vector control approaches
34868Rita Mwima, Tin-Yu J. Hui, Edward Lukyamuzi, et al, bioRxiv, 2025-05-26 21:26:56.
This study collected 2918 Anopheles gambiae and 173 Anopheles. arabiensis across six populations from both the islands on Lake Victoria and mainland Uganda for amplicon sequencing. Large pairwise FST values were observed between the two species, indicating their divergence. We observed low but often significant FST values between the 6 An. gambiae populations, while between the An. arabiensis mainland populations, FST values were not significant. Principal Component Analysis also revealed strong genetic structure between the two species but did not provide a clear picture between populations within each species. We also found that mainland An. gambiae populations had higher within population genetic diversity than the islands’, while An. arabiensis had the lowest nucleotide diversity. Tajima’s D values were all negative, suggesting a recent population expansion. The islands An. gambiae populations had very low contemporary effective population sizes in the tens and hundreds, as estimated from linkage disequilibrium, while the mainland population sizes were consistently higher, in the thousands.
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.
Unstable laboratory Wolbachia strain w-Anga is negatively correlated with Plasmodium falciparum in wild malaria vectors
34856Estelle, D.L., Jacques, G.E., Issiaka, S. et al., Scientific Reports, 15. 2025-05-26 20:48:59.
Spread of insecticides resistance threatens the control of malaria. In this context, biological control using an endosymbiotic bacterium Wolbachia is being explored as a complementary method for its control. However, for optimal use of this bacterium in biocontrol strategies, it is imperative to characterize it. So, Anopheles gambiae complex mosquitoes were collected, morphologically identified, then blood fed and gravid female mosquitoes oviposited individually. After oviposition, the species of parent was molecularly determined, along with their w-Anga infection status. Additionally, we performed 16SrRNA gene sequencing of w-Anga-positive mosquitoes to determine their phylogeny. Finally, we amplified gene encoding the circumsporozoite protein to determinate their Plasmodium falciparum infection status and assessed the stability of w-Anga transmission of positive females and their offspring. From the results obtained, our w-Anga strains cluster with other Wolbachia Supergroup B strains. However, the prevalence of Plasmodium falciparum infection was lower in Wolbachia-infected females (4.59%) than in those uninfected (22.02%). Furthermore, the transmission frequency of this bacterium in infected Anopheles coluzzii females of the F0 generation to F1 offspring was 10.64% and 16.67% from infected females of the F1 generation to F2 offspring. This study results will serve as preliminary data for the possible use of Wolbachia in malaria control.
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.
A male-transmitted B chromosome undergoes strong meiotic drag in females
34850Patrick M Ferree, Jayla Cummings, Emma Garman, et al, bioRxiv, 2025-05-26 20:12:34.
Many organisms carry extra, non-essential chromosomes known as B chromosomes (Bs), which are selfishly transmitted at super-Mendelian levels to offspring. This heightened transmission, termed drive, occurs during gametogenesis, usually in one of the two parents. In some cases, Bs can experience an opposing process, drag, which reduces their transmission. If these processes occur together in the same organism, one in each parental sex, then they may facilitate the spread of Bs while countering their accumulation in the genome to harmful levels. While previous studies have elucidated mechanistic aspects of B drive, little is known about drag or other factors that govern the inheritance of these selfish genetic elements. Here we examined the inheritance of Paternal Sex Ratio (PSR), a single-copy B in the jewel wasp, Nasonia vitripennis, which is transmitted paternally to offspring. PSR drives by converting female-destined embryos into PSR-transmitting males. Using genetic manipulation, we produced exceptional PSR-carrying females, which were used to assess B transmission potential. We found that females transmit PSR at unexpectedly low levels compared to univalent chromosomes in other organisms. This reduced transmission stems from remarkable loss of PSR from the egg's nucleus upon entry into meiosis, an effect that may be caused by an absence of microtubule-based spindle fibers in meiosis I-arrested wasp eggs. We also found that PSR is strictly limited to a single copy per genome, suggesting that two PSR copies are lethal during development. Our findings reveal the successful inheritance of this selfish B chromosome involves a restriction to a single copy and hidden female meiotic drag in addition to its strong paternal drive.
Evaluating the impact on F1 sterility of tsetse pupae Glossina morsitans morsitans irradiated following short-term hypoxic conditioning
34848Caroline K. Mirieri, Kiswend-sida M. Dera, Vanessa S. Dias, et al, Insect Science, 2025-05-26 20:07:11.
The sterile insect technique (SIT) for tsetse involves releasing sterilized males to outcompete wild males in mating, resulting in nonviable progeny. Balancing optimum sterility and male quality is crucial. While irradiation in hypoxia or anoxia is routine for tephritid flies, its effect on tsetse, especially postrelease, is not well understood. We conducted experiments to understand the impact of irradiation in hypoxia on the sterility of the F1 generation of Glossina morsitans morsitans (Gmm). Initially, we tested the impact of 1-h preconditioning in hypoxia before irradiation and continued hypoxia up to 24, 48, and 72 h postirradiation on the emergence and flight propensity of treated males. We then assessed mating ability, survival, pupae per initial female (PPIF) and residual fertility of flies following irradiation at various doses after 1-h hypoxia conditioning. Finally, we determined the PPIF and residual fertility of the F1generation and the emergence of treated flies to the F2 generation. Results show that short-term conditioning (1 h) in hypoxia maintains or improves the qualities of the irradiated Gmm pupae. Regardless of irradiation in normoxia or hypoxia, higher residual fertility was observed in females than males in the F0 generation, and higher residual fertility in the F1 than the F0 generation for both sexes. However, the emergence rates of males decreased in the F2 generation compared with the F1 generation, a noteworthy finding for SIT programs for tsetse, implying diminishing populations of sterile flies.
Spiroplasma infection in colonized Glossina fuscipes fuscipes: impact on mass rearing and the sterile insect technique
34846Kiswend-sida M. Dera, Daouda Tande Barro, Bénéwendé Aristide Kaboré, et al, Insect Science, 2025-05-26 20:02:52.
Tsetse flies (Glossina spp.) can vector the parasites (Trypanosoma spp.) that cause the socioeconomically devastating neglected tropical diseases human and animal African trypanosomoses. In addition to this parasite, tsetse can harbor four genera of endosymbiotic bacteria, including Wigglesworthia, Sodalis, Wolbachia, and Spiroplasma, which are functionally crucial for the fly's physiological homeostasis and/or are potentially useful for the development of disease control strategies. Recent discoveries indicate that Spiroplasma infection negatively impacts tsetse fecundity. Conversely, housing the bacterium can benefit its fly host by making it unusually refractory to infection with parasitic African trypanosomes. In this study, we assessed the physiological impact of Spiroplasma infection on a laboratory colony of Glossina fuscipes fuscipes (Gff). For this purpose, two distinct Gff colonies were established: a Spi– colony that harbors a low Spiroplasma infection prevalence and a Spi+ colony that harbors a high Spiroplasma infection prevalence. Fitness parameters for both colonies revealed no significant differences in the length of larval development, adult eclosion rate, and flight propensity. However, flies from the Spi+ colony presented with lower fecundity and higher overall mortality than did individuals from the Spi– colony. Furthermore, males from the Spi– colony exhibited a competitive mating advantage over their Spi+ counterparts in a field cage setting. These findings have potential implications for the improvement of mass-rearing of Gff for sterile insect technique (SIT) applications.
Deliberate extinction by genome modification: An ethical challenge
35544Gregory E. Kaebnick et al., Science, 388:707-709. 2025-05-15 10:35:25.
Among the ways that genome modification could be used to modify wild populations of organisms, the deliberate outcome of fully eradicating a species has received little critical attention. The lack of discussion leaves a difficult ethical question unresolved: When so much attention is given to the value of biodiversity and the conservation of species, what circumstances, paradoxically, might justify the deliberate, full extinction of a species? At least one species is now a preliminary candidate for full extinction, and cases under consideration for temporary suppression and local extinction might pose a risk of full extinction. We discuss three cases in which genome modification might be used to eradicate a species. Together, we argue, these cases suggest that deliberate full extinction might occasionally be acceptable, but only extremely rarely. The cases also highlight tensions within some widely held views about the conservation of species and the governance of genome editing.
Biased tertiary sex ratios enhance the efficacy of sex-ratio distorting genetic techniques to control invasive species
34843Michael L. Jones, Ronald E. Thresher, Nicholas J. Bax, Journal of Theoretical Biology, 2025-05-12 20:32:40.
Genetic biocontrol strategies are increasingly being developed and tested for reducing the effects of invasive species, and are highly likely to be an important tool of integrated pest management in the future. Included among such strategies are those that distort the sex ratio of the target species. Models used to forecast the efficacy of such strategies generally assume, implicitly, that the tertiary sex ratio of the target population is 50:50. We present evidence that this assumption is important, and that if the tertiary sex ratio is biased towards females, a sex-distorting construct introduced into the population that produces phenotypic males will become fixed at a level determined by the magnitude of the bias, even after further introductions cease. We show, first using a simple logistic population model, and second using a realistic simulation of an important aquatic invasive species – the sea lamprey Petromyzon marinus – how this effect can greatly increase the effectiveness of a sex-distorting construct at population suppression, but also increase the risk of such strategies due to reduced reversibility. We also present evidence that biased tertiary sex ratios might be present in many invasive species, particularly when their population sizes are low relative to environmental carrying capacity.
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.
Functional validation of a white pupae minimal gene construct in Ceratitis capitata
34835Lucas Henrique Figueiredo Prates, Roswitha A. Aumann, Inga Sievers, et al., Insect Science, 2025-05-12 19:41:58.
Genetic sexing strains (GSS) are important tools for the sterile insect technique (SIT), an environmentally friendly and species-specific insect pest control method. GSS feature sex-specific phenotypes, enabling sex sorting in mass-rearing facilities and male-only releases, which significantly improve the cost-effectiveness and efficiency of SIT programs. In classical GSS, sex linkage of marker gene(s), such as white pupae (wp), is achieved through an irradiation-induced translocation between the marker-carrying autosome and the Y chromosome. However, this approach may render GSS males semisterile. The recently proposed neo-classical GSS concept suggests using genome editing to achieve sex linkage by directly inserting the wild-type marker allele onto the Y chromosome, potentially yielding GSS males with higher fertility. In this study, we examined the Ceratitis capitata wp gene as a genetic marker for the neo-classical GSS concept and developed a minimal, intronless version of this gene, termed mini-wp. We demonstrate that a single copy of mini-wp is sufficient to restore the wild-type brown puparium phenotype and is functional when integrated at various positions within the C. capitata genome, including the X chromosome. Due to its smaller size (4689 bp, including 2000 bp of putative promoter region) relative to the full wild-type wp allele (20868 bp), mini-wp may facilitate its precise insertion into the Y chromosome, representing an important step toward realizing neo-classical GSS. Furthermore, the methodology developed for designing and testing mini-wp in medfly may be adapted to other Tephritid species with an identified wp gene.
Nanobody-mediated targeting of Plasmodium falciparum PfPIMMS43 can block malaria transmission in mosquitoes
34819Ukegbu, C.V., Mohamed, M., Hoermann, A. et al., Communications Biology, 8. 2025-05-04 18:21:46.
The transition from ookinete to oocyst is a critical step in the Plasmodium falciparum lifecycle and an important target for malaria transmission-blocking strategies. PfPIMMS43, a surface protein of P. falciparum ookinetes and sporozoites, is critical for this transition and aids the parasite in evading mosquito immune responses. Previous studies demonstrated that polyclonal PfPIMMS43 antibodies reduced P. falciparum infection in Anopheles mosquitoes. Here, building on these findings, we have developed high-affinity single-domain VHH antibodies (nanobodies) derived from llama heavy-chain-only antibodies. We have shown that these nanobodies bind both recombinant and endogenous PfPIMMS43 produced by P. falciparum ookinetes in the mosquito midgut. Importantly, they significantly reduce infection intensity and prevalence of laboratory and field strains of P. falciparum in An. coluzzii and An. gambiae, respectively. Epitope mapping has revealed that the nanobodies target conserved regions in the second half of PfPIMMS43, with homology modelling confirming epitope accessibility. These findings establish PfPIMMS43 as a promising transmission-blocking target. To enhance malaria control and elimination efforts, we propose an innovative strategy in which genetically modified mosquitoes express PfPIMMS43-specific nanobodies in their midguts and spread this trait in wild mosquito populations via gene drive technology.
Maximising Eradication Potential of Rat Gene Drives Using a Two-Target Homing Rescue Strategy: Spatial Modelling of Empirical Data
34817Birand, A., Gierus, L., Prowse, T., Cassey, P., Thomas, P.Q., Molecular Ecology, 2025-05-04 16:12:38.
Gene drives are genetic elements with positively biased transmission and may be useful tools to suppress mammalian pests that threaten biodiversity worldwide. While gene drives are progressing in mice, less is known about their potential for invasive rat control. A recent report has provided the first data on germline gene conversion in rats, demonstrating that modest homing rates (up to 67%) can be achieved in females. Here, we apply these empirically derived values to investigate the potential of various gene drive strategies to suppress an island population of 200,000 rats, using our stochastic, spatially explicit, individual-based modelling framework. Standard homing drives embedded in haplosufficient fertility or viability genes failed to eradicate, but achieved permanent population suppression. In contrast, a two-target design with a homing rescue (HR) drive embedded in a haplolethal gene that also targets an independent fertility or viability gene demonstrated considerable suppression potential. Remarkably, an HR drive targeting a haplosufficient female fertility gene showed robust eradication even at the relatively low homing rates previously demonstrated in rats. Interestingly, homing rate had a relatively low influence on eradication probability while cutting efficiency at the haplolethal gene was critical. Further, as long as the latter was similar to the cutting and subsequent knockout of the unlinked female fertility gene, then eradication could be achieved across a range of homing rates. Together, these results suggest that modest homing rates, such as have been demonstrated in rats and other species, can potentially be leveraged for population suppression, offering new opportunities for gene drive development.
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.”
Economic evaluation of Wolbachia deployment in Colombia: A modeling study
34812Shepard, D.S., Lee, S.R., Halasa-Rappel, Y.A., Rincon Perez, C.W., Harker Roa, A., PLoS One, 20. 2025-05-04 15:55:06.
Wolbachia are bacteria that inhibit dengue virus replication within the mosquito. A cluster-randomized trial in Indonesia found Wolbachia reduced virologically-confirmed dengue cases by 77.1%. Previous models predicted Wolbachia to be highly cost-effective in Indonesia, Vietnam, and Brazil. To inform decisions about future extensions in Colombia, we performed economic evaluations of potential Wolbachia deployments in 11 target cities. We assembled the numbers and distribution by severity of reported dengue cases from Colombia’s national disease surveillance system and the health service provision registry (RIPS). An epidemiological panel of three experts estimated the shares of dengue that were non-medical, under-reported, or misreported as another disease. We determined costs (in 2020 US dollars at market prices) of treating dengue illness from the benchmark insurance tariff and RIPS data on treatment services per symptomatic dengue case. Our central estimates projected 10 years of efficacy and focused on Cali, the target city with the highest number of dengue cases. For Cali, we estimated a net health-sector savings of US$4.95 per person and averting 369 disability-adjusted life years (DALYs) per 100,000 population. From a societal perspective, at 10 years Wolbachia deployment is expected to have highly favorable benefit-cost ratios, with benefits per dollar invested of US$5.50 in Cali and US$4.68 over all target cities. Over 10 years, Wolbachia is highly beneficial on economic grounds, and almost universally cost saving. The Wolbachia program’s economic benefits exceeded its costs in all 11 cities. The program’s savings in healthcare costs alone would more than offset deployment costs nationally and in 9 of 11 target cities. Wolbachia is likely to be the most cost-effective or cost-saving dengue control option in municipalities with both high incidence of dengue and high population density, whereas areas with high dengue incidence but low population density should consider vaccination.
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.
A selfish supergene causes meiotic drive through both sexes in Drosophila
34805G.L. Keais,C.M. Saad-Roy,E. Gonzalez-Sqalli, et al., Proceedings of the National Academy of Sciences, 122. 2025-04-25 12:15:11.
Meiotic drivers are selfish genetic elements that bias their own transmission during meiosis or gamete formation. Due to the fundamental differences between male and female meiosis in animals and plants, meiotic drivers operate through distinct mechanisms in the two sexes: In females, they exploit the asymmetry of meiosis to ensure their inclusion in the egg, whereas in males, they eliminate competing gametes after symmetric meiosis. Meiotic drive is commonly reported in males, where it strongly influences the evolution of spermatogenesis, while the few known cases in females have highlighted its crucial role in centromere evolution. Despite a growing number of examples in a wide range of organisms, meiotic drive has so far only been observed in one sex or the other since its discovery nearly 100 y ago. Here, we show that a selfish X chromosome known to cause meiotic drive in male Drosophila testacea flies also causes meiotic drive in females. We find that this X chromosome has supergene architecture, harboring extensive structural rearrangements that suppress recombination between the two X chromosomes. This has contributed to a substantial expansion of its size compared to the wild-type chromosome, partly due to the accumulation of species-specific repetitive elements. Our findings suggest that female meiotic drive may play an important role in the evolutionary dynamics of polymorphic structural variants that suppress recombination, including inversions, translocations, and supergenes.
Optimization of SgRNA expression with RNA pol III regulatory elements in Anopheles stephensi
34801Gonzalez, E., Anderson, M.A.E., Ang, J.X.D. et al., Scientific Reports, 15. 2025-04-23 11:08:06.
Anopheles stephensi, a major Asian malaria vector, is invading Africa and has been implicated in recent outbreaks of urban malaria. Control of this species is key to eliminating malaria in Africa. Genetic control strategies, and CRISPR/Cas9-based gene drives are emerging as promising species-specific, environmentally friendly, scalable, affordable methods for pest control. To implement these strategies, a key parameter to optimize for high efficiency is the spatiotemporal control of Cas9 and the gRNA. Here, we assessed the ability of four RNA Pol III promoters to bias the inheritance of a gene drive element inserted into the cd gene of An. stephensi. We determined the homing efficiency and examined eye phenotype as a proxy for non-homologous end joining (NHEJ) events in somatic tissue. We found all four promoters to be active, with mean inheritance rates up to 99.8%. We found a strong effect of the Cas9-bearing grandparent (grandparent genotype), likely due to maternally deposited Cas9.
Stronger population suppression by gene drive targeting doublesex from dominant female-sterile resistance alleles
34799Weizhe Chen, Ziye Wang, Jackson Champer, bioRxiv, 2025-04-23 11:00:18.
CRISPR homing drives can be used to suppress a population by targeting female fertility genes. They convert wild-type alleles to drive alleles in the germline of drive heterozygotes by homology-directed repair after DNA cleavage. However, resistance alleles produced by end-joining pose a great threat to homing drive. They prevent further recognition by Cas9, and therefore weaken suppressive power, or even stop suppression if they preserve the function of the target gene. We used multiplexed gRNAs targeting doublesex in Drosophila to avoid functional resistance and create resistance alleles that were dominant female-sterile. This occurred because the male dsx transcript was generated in females by disruption of the female-specific splicing acceptor site. We rescued dominant sterility of the drive by providing an alternate splicing site. As desired, the drive was recessive female sterile and yielded high drive inheritance among the progeny of both male and female drive heterozygotes. The dominant-sterile resistance alleles enabled stronger suppression in computational models, even in the face of modest drive efficiency and fitness costs. However, we found that male drive homozygotes were also sterile because they used the rescue splice site. Attempts to rescue males with alternate expression arrangements were not successful, though some male homozygotes had less severe intersex phenotypes. Though this negatively impacted the drive, models showed that it still had significantly improved suppressive power. Therefore, this design may have wide applicability to dsx-based suppression gene drives in a variety of organisms with intermediate homing drive performance.
An eco-epidemiological model for malaria with Microsporidia MB as bio-control agent
34793Mfangnia CNT, Tonnang HEZ, Tsanou B, Keith Herren J, Modeling Earth Systems and Environment, 11. 2025-04-23 10:24:11.
Microsporidia MB is an endosymbiont which naturally infects Anopheles mosquitoes. Due to its ability to block Plasmodium transmission, it shows potential as a bio-based agent for the control of malaria. Its self-sustainability is promising, as it can spread through both vertical and horizontal transmissions. However, its low prevalence in mosquito populations remains a challenge. We develop an eco-epidemiological mathematical model describing the co-dynamics of Microsporidia MB (within mosquito population) and malaria (within human population). The model is used to assess the potential of Microsporidia MB-infected mosquitoes on the control of malaria infection. The results on the basic reproduction numbers, the stability of the equilibria, and the existence of bifurcations are obtained, providing conditions for the extinction and persistence of MB-infected mosquitoes. We highlight relevant threshold parameters for the elimination and persistence of MB-infected mosquitoes and malaria-infected individuals. Using real data from Kenya, we found that, given a horizontal transmission rate between 0 and 0.5, a minimum vertical rate of 0.55 is required to avoid extinction of MB-infected mosquitoes. The predicted prevalence of MB-infected mosquitoes using transmission rates reported from lab experiments align with the observed low prevalence of MB-infected mosquitoes in the field, thereby validating our model and results. Finally, predictions indicate that increasing MB mosquito infection could effectively control malaria, with target prevalence varying by region: 15% in Highland, 40% on the coast, and 70% in the Lake region. This study offers insights into the use of bio-based vector population replacement solutions to reduce malaria incidence in regions where Microsporidia MB is prevalent.
International perspectives on the meaning of engagement in biotechnology risk assessment: the case of gene drive
34789Hartley, S., Stelmach, A., Kokotovich, A., & Smith, R. D. J., Journal of Risk Research, 2025-04-23 10:10:43.
Biotechnology remains challenging for risk assessors. The risk assessment of genetically modified organisms was the locus of considerable, acrimonious, and politicised debate and subjected to intense scrutiny. Since then, biotechnology has evolved to include new tools, such as genome editing and gene drive, and risk assessors are more sensitive to stakeholder and public views. While engagement is increasingly recognised as important in risk governance, it is underrepresented in the governance literature, remains challenging in risk assessment, and needs empirical cases to develop theory. Imagining engagement in risk assessment will require thinking about when, where, and how to engage people in risk assessment processes in both research and regulatory contexts. However, current risk assessment methods and processes make engagement of non-technical experts challenging and risk assessors may need to innovate and diverge from the norms of risk assessment. Gene drive presents a case of risk assessment that has generated a plethora of prescriptive calls and recommendations for engagement. We use this case study to explore how both technical and non-technical experts and stakeholders involved in gene drive risk assessment are imagining engagement. We conduct qualitative, interpretive research, drawing on 30 interviews with participants across five continents. We show that the people involved with engagement in risk assessment are talking about drastically different things when they talk about engagement. Placing an empirical and theoretical spotlight on engagement in risk assessment, we argue that conversations need to draw on our insights to move beyond simply recognising, justifying, and calling for engagement.
Mathematically modelling the population dynamics of CRISPR gene drive systems in the pine pest Sirex noctilio
34779Strydom, H., Ouifki, R., Chapwanya, M., bioRxiv, 2025-04-18 10:34:17.
Sirex noctilio is an invasive pest of pine that has caused significant economic damage in South Africa and many other Southern Hemisphere countries. Current management tools are not efficient in all cases and consequently there is a need for more efficient and targeted control measures. An emerging tool for pest management is the use of gene editing and associated gene drive systems. In this study, we aim to investigate the use of CRISPR-Cas gene drive systems in the management of S. noctilio in South Africa. As a first step, we developed a model for the population dynamics of S. noctilio, using historical national population monitoring data and incorporating the influence of two main biological control agents of the pest. We then modelled the influence of two different CRISPR-Cas systems on the population dynamics of S. noctilio namely, a baseline CRISPR model and Complementary Sex Determination CRISPR (CSD) model. Each model is used to simulate a male and female only introduction strategy to estimate the effectiveness of different methods of introducing the gene drive system. The model calibration was achieved by optimizing the model fit to existing data using the least squares technique. Results suggest that both CRISPR gene drive systems would be effective at controlling the population growth of S. noctilio at high levels of introduction, but overall population control would be hindered by practical limitations. Although only two CRISPR models were explored, the underlying population model serves as a framework for further studies into the population dynamics of Sirex noctilio, as well as many other CRISPR-Cas gene drive systems.
Evolutionary consequences of long-distance dispersal in mosquitoes
34776Thomas L Schmidt, Current Opinion in Insect Science, 68. 2025-04-18 10:25:09.
Long-distance dispersal (LDD) provides a means for mosquitoes to invade new regions and spread adaptive alleles, including those conferring insecticide resistance. Most LDD takes place on human transport vessels and will typically be rarer and more directionally constrained than active flight but can connect populations and regions that are otherwise mutually inaccessible. These features make LDD worthy of specific consideration in mosquito research. This paper reviews recent evolutionary research on LDD and its consequences for mosquito populations and mosquito control. LDD is the main source of mosquito range expansions, and genomic methods can now trace the origins of new invasions to specific towns or cities. Genomic methods can also give a rough indication of the number of invaders, which if very small may lead to the stochastic loss of advantageous alleles during invasion bottlenecks. Once invasions are established, LDD spreads adaptive alleles between populations. Emerging insights into insecticide resistance evolution indicate that LDD has repeatedly spread resistance mutations across global species ranges, but these broad patterns are convoluted by two other evolutionary processes: parallel adaptation at the same gene or gene cluster and polygenic adaptation at different genes in different populations. Together, these processes have produced patterns of similarity and dissimilarity at resistance genes that are decoupled from geographical distance. LDD within cities is less well studied but is important for planning and evaluating local control efforts. Urban investigations of LDD may help identify areas experiencing weaker selection pressures from insecticides and isolated areas to target for control.
Applications and status of gene drive in plants
34771Hay BA, PLOS Biology, 23. 2025-04-18 10:06:07.
Globalization—the movement of humans, plants, animals, and microbes—together with climate change, place numerous plant and animal species under novel stresses. For plants, threats include global warming, invasive species, weeds, animal pests, and vectors of disease. Harms can be mitigated or prevented through population-scale genetic alterations that introduce beneficial traits such as disease resistance or drought tolerance (population modification), or that eliminate a harmful population (population suppression). Gene drive is a possible tool for achieving these goals. DNA mediating gene drive comprises one or more genes (the drive element) that promote their own inheritance—and any linked cargo—at rates exceeding (>50%) those of other genes. This can lead to an increase in drive element frequency even if its presence results in a fitness cost to carriers. Gene drive is attractive because it is self-amplifying and self-sustaining. One class of gene drive utilizes a Toxin-Antidote (TA) element. In nature, these often consist of two tightly linked protein-encoding genes. One encodes a toxin that is inherited by all gametes and/or progeny of a carrier; the second is an antidote that protects carriers from death. The TA element-bearing chromosome gains a relative transmission advantage by causing death of those who fail to inherit it. The first synthetic gene drive was engineered using TA logic, in Drosophila melanogaster in 2007. Recently, TA logic was also used to create the first synthetic gene drive elements in plants, in Arabidopsis thaliana. These use a Cleave and Rescue mechanism (ClvR) adapted from earlier work in Drosophila. ClvR uses DNA cleavage mediated by Cas9 and guide RNAs (gRNAs), followed by inaccurate repair, to create loss-of-function (LOF) alleles (the toxin) of endogenous versions of an essential gene. ClvR also includes a Rescue version of the essential gene recoded to prevent gene disruption (the antidote), which guarantees survival of carriers. In Drosophila, ClvR spreads because LOF alleles created in parents cause the death of progeny who lack essential gene function. In Arabidopsis this strategy was used to create gamete killers. A naturally occurring male gamete killer from rice, DUYAO-JIEYAO, consists of a two-gene protein–protein TA cassette. Modeling suggests that gamete killers such as these can bring about population modification or suppression. Interestingly, the DUYAO-JIEYAO element has undergone a substantial increase in frequency in Japonica rice populations in China over the last 50 years, demonstrating the power of such elements in nature.
Problem formulation for a small-scale field study of non-gene drive, genetically modified, male bias mosquitoes in Burkina Faso
34758Hayes, K. R., & Hosack, G. R., Human and Ecological Risk Assessment: An International Journal, 2025-04-10 09:17:32.
This article documents the problem formulation step of a risk assessment for a proposed small-scale field release in Burkina Faso of genetically modified (GM) An. coluzzii mosquitoes that carry a Paternal Male Bias (PMB) construct. These mosquitoes are part of the pathway developed by Target Malaria to provide a new cost-effective control strategy for malaria vectors in Africa. The problem formulation describes 7 potentially harmful outcomes that might occur through 19 pathways to harm and identifies 22 types of desk-based analysis, 6 laboratory tests, and 5 field observations that can be used to test the risk hypotheses associated with these pathways. The problem formulation forms the basis of a prerelease risk assessment that meets the standards stipulated under the Cartagena Protocol and guidance provided by the World Health Organization, the African Union Development Authority, and the European Food Safety Authority. The Problem Formulation reflects the concerns expressed about the proposed field release by relevant stakeholders, although stated concerns are not always specific enough to be unambiguously associated to a single pathway. The presentation of the pathways to harm emphasizes the types of evidence that supports the steps within each pathway, and so portrays the speculative nature of some pathways.
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.
An innovation in host responses to escalating genomic conflicts
34753Martí, Emiliano et al., Trends in Genetics, 2025-04-07 12:54:24.
Conflicts between selfish elements and their hosts can trigger rapid structural and regulatory changes in genomes. Chen et al. discovered a novel species-specific innovation in response to a meiotic driver in Drosophila melanogaster. Their discovery highlights a new dimension in adaptive responses to selfish elements, with broad evolutionary consequences.
Anticipating evolutionary responses of mosquito mating systems to population suppression with mass-reared males
34745Bonsall, M.B., Cator, L.J., Current Opinion in Insect Science, 68. 2025-04-06 19:52:32.
Strategies that rely on the mass release of males to suppress mosquito populations will exert selective pressure on natural mating systems. Here, we investigate how mass releases might affect the mating behaviors of wild target populations. We highlight gaps in our understanding of both variation in these aspects of mosquito behavior and the evolutionary forces that maintain variation within and between populations. We provide a mathematical framework for integrating mosquito mating ecology into models of population suppression. Given that these strategies are being increasingly deployed, anticipating and managing evolutionary responses of target population behavior should be a priority for research.
Wolbachia: A bacterial weapon against dengue fever- a narrative review of risk factors for dengue fever outbreaks
34743Safaei, S., Derakhshan-Sefidi, M., Karimi, A., New Microbes and New Infections, 65. 2025-04-04 14:53:55.
Arboviruses constitute the largest known group of viruses and are responsible for various infections that impose significant socioeconomic burdens worldwide, particularly due to their link with insect-borne diseases. The increasing incidence of dengue fever in non-endemic regions underscores the urgent need for innovative strategies to combat this public health threat. Wolbachia, a bacterium, presents a promising biological control method against mosquito vectors, offering a novel approach to managing dengue fever. We systematically investigated biomedical databases (PubMed, Web of Science, Google Scholar, Science Direct, and Embase) using “AND” as a Boolean operator with keywords such as “dengue fever,” “dengue virus,” “risk factors,” “Wolbachia,” and “outbreak.” We prioritized articles that offered significant insights into the risk factors contributing to the outbreak of dengue fever and provided an overview of Wolbachia's characteristics and functions in disease management, considering studies published until December 25, 2024. Field experiments have shown that introducing Wolbachia-infected mosquitoes can effectively reduce mosquito populations and lower dengue transmission rates, signifying its potential as a practical approach for controlling this disease.
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.
