For Researchers

The Sterile Insect Technique can efficiently reduce the reproduction of the spotted wing drosophila (Drosophila suzukii) in strawberry

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B. Gard, A. Panel, A. Labbetoul, N. Bosshard, A. Xuereb, B. Cariou, A. Debelle, C. Oliva, S. Fellous,  bioRxiv,  2023-12-11 13:19:11.
The spotted wing drosophila (SWD) Drosophila suzukii (Diptera: Drosophilidae) is a highly problematic pest in soft fruit crops. Since its introduction in Europe in 2008, no satisfying nor environment-friendly control method has emerged against this species. The sterile insect technique (SIT) has proven efficient at controlling numerous fruit fly species. In recent years, key elements of SIT against D. suzukii have become available, leading to the publication of encouraging results. However, field- and field-like experiments are notoriously under the influence of various, often unidentified factors granting the need for replicated studies. In this experiment, we assayed the efficacy of a high-performance strain at reducing the reproduction of D. suzukii in complex, yet replicated and controlled conditions. Two ratios of sterile to fertile insects (5:1 and 1:1) using bisexual releases were compared to a control treatment with fertile, wild flies only. The presence of sterile individuals at a 5:1 ratio significantly reduced fly reproduction, measured after 5 days, by an approximate threefold factor. However, the proportion of infested fruits in the treated plots remained unaffected. The number of available berries in the cage appeared as an unexpected determinant of fly infestation, suggesting undocumented density-dependent processes. The success of this assay opens the door to larger scales experiments, over several generations, and, in the near future, the field-evaluation of the efficacy of the SIT to control D. suzukii.

Population suppression with dominant female-lethal alleles is boosted by homing gene drive

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Jinyu Zhu, Jingheng Chen, Yiran Liu, Xuejiao Xu, Jackson Champer,  bioRxiv,  2023-12-07 10:24:25.
Methods to suppress pest insect populations using genetic constructs and repeated releases of male homozygotes have recently been shown to be an attractive alternative to older sterile insect technique based on radiation. Female-specific lethal alleles have substantially increased power, but still require large, sustained transgenic insect releases. Gene drive alleles bias their own inheritance to spread throughout populations, potentially allowing population suppression with a single, small-size release. However, suppression drives often suffer from efficiency issues, and the most well-studied type, homing drives, tend to spread without limit. In this study, we show that coupling female-specific lethal alleles with homing gene drive allowed substantial improvement in efficiency while still retaining the self-limiting nature (and thus confinement) of a lethal allele strategy. Using a mosquito model, we show the required releases sizes for population elimination in a variety of scenarios, including different density growth curves, with comparisons to other systems. Resistance alleles reduced the power of this method, but these could be overcome by targeting an essential gene with the drive while also providing rescue. A proof-of-principle demonstration of this system in Drosophila melanogaster was effective in both basing its inheritance and achieving high lethality among females that inherit the construct in the absence of antibiotic. Overall, our study shows that substantial improvements can be achieved in female-specific lethal systems for population suppression by combining them with a gene drive.

The effect of migration on transmission of Wolbachia in Nilaparvata lugens

28679
Zhigang Liu, Tiejun Zhou,  Mathematical Biosciences and Engineering,  20. 2023-12-06 13:40:37.
Brown planthopper Nilaparvata lugens, which can transmit rice ragged stunt virus, is a serious and damaging pest to rice plants. Rice plants can protect themselves from the associated diseases of N.lugens by either suppressing or replacing N.lugens by releasing N.lugens infected by a special strain of Wolbachia wStri. The long-distance migration habit of N.lugens is one of the important precursors leading up to the large-scale occurrence of N.lugens. To study the effect of migration on the transmission of Wolbachia in N.lugens, a Wolbachia spreading dynamics model with migration of N.lugens between two patches is put forward. The existence and local stability conditions of equilibrium points of the system and its subsystems are obtained. Moreover, the effects of migration on the dynamic properties and the control of N.lugens are analyzed; the results show that the system can exhibit a bistable phenomenon, and the migration can change the stability of equilibrium infected with wStri from stable to unstable. The quantitative control methods for the migration of the insect N.lugens are proposed, which provide a theoretical guidance for future field experiments. Lastly, we use the Markov chain Monte Carlo (MCMC) method to estimate the parameters of the wild N.lugens migration model based on limited observational data; the numerical simulation results show that migration can increase the quantity of N.lugens, which is consistent with the relevant experimental results.

Viruses that ‘infect’ viruses: Cas12f1 and Cas9 gene drive in HSV1

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Hongsheng Dai, Qiaorui Yao, Zhuangjie Lin, Keyuan Lai, Xianyin Zeng, Guangxiong Lei, Tongwen Zhang,  bioRxiv,  2023-12-06 12:08:32.
Cas9-based synthetic gene drives constitute some minimal elements capable of editing DNA with sequence specificity. However, they face high resistance rate and mitigation strategies developed so far are difficult to implement. Here, we engineered herpes simplex virus type 1 (HSV1) as a vector for gene drive, generated viruses carrying either Cas9 or Cas12f1 gene drives, and compared their performance in spreading the gene drive and causing resistance. Based on phenotypical staining and NGS sequencing, we showed that HSV1 supported fast and effective transmission of gene drive, and Cas12f1 gene drive yielded higher conversion and lower resistance than Cas9 gene drive. Cas12f1 gene drive is a promising alternative to Cas9 gene drive, and HSV1 is a reliable and fast platform to evaluate gene drive. Gene drive viruses worked like pathogens that specifically infect viruses and could potentially be used to attenuate viral infection.

A population modification gene drive targeting both Saglin and Lipophorin impairs Plasmodium transmission in Anopheles mosquitoes

28671
Emily I Green, Etienne Jaouen, Dennis Klug, Roenick Proveti Olmo, Amandine Gautier, Stéphanie Blandin, Eric Marois,  eLife,  12. 2023-12-06 11:55:36.
Lipophorin is an essential, highly expressed lipid transport protein that is secreted and circulates in insect hemolymph. We hijacked the Anopheles coluzzii Lipophorin gene to make it co-express a single-chain version of antibody 2A10, which binds sporozoites of the malaria parasite Plasmodium falciparum. The resulting transgenic mosquitoes show a markedly decreased ability to transmit Plasmodium berghei expressing the P. falciparum circumsporozoite protein to mice. To force the spread of this anti-malarial transgene in a mosquito population, we designed and tested several CRISPR/Cas9-based gene drives. One of these is installed in, and disrupts, the pro-parasitic gene Saglin and also cleaves wild-type Lipophorin, causing the anti-malarial modified Lipophorin version to replace the wild type and hitch-hike together with the Saglin drive. Although generating drive-resistant alleles and showing instability in its gRNA-encoding multiplex array, the Saglin-based gene drive reached high levels in caged mosquito populations and efficiently promoted the simultaneous spread of the antimalarial Lipophorin::Sc2A10 allele. This combination is expected to decrease parasite transmission via two different mechanisms. This work contributes to the design of novel strategies to spread antimalarial transgenes in mosquitoes, and illustrates some expected and unexpected outcomes encountered when establishing a population modification gene drive.

Homing-based gene drives can introgress rapidly into local genetic backgrounds with minimal chromosomal conversion in Anopheles gambiae

28663
Tony Nolan, Poppy Pescod, Giulia Bevivino et al.,  Research Square,  2023-12-06 10:02:37.
CRISPR-Cas9 gene drive control strategies use a homing selfish genetic element which induces a double-stranded break at the target site and is copied into the opposing chromosome, breaking an essential gene and ensuring super-Mendelian inheritance. During the copying process SNPs could potentially be transferred from one chromosome to another, converting tracts of the target to match the recipient. This would reduce the ability of gene drives to escape their genetic background of origin, with potential impacts on carrier fitness and the success of the strategy. In this study we use Anopheles gambiae strains with variation around the target site to determine the extent of chromosomal conversion during gene drive activity and the mechanism of inheritance bias. We confirm a homing-based mechanism and show that two thirds of homing events are resolved within 50 bp, showing that gene drive introgression into a wild strain can occur within one generation.

Germline transformation of the West Nile Virus and avian malaria vector Culex quinquefasciatus Say using the piggyBac transposon system

28653
Katherine Nevard, Rajdeep Kaur, Tim Harvey-Samuel,  bioRxiv,  2023-12-05 11:04:04.
Culex quinquefasciatus Say is a mosquito which acts as a vector for numerous diseases including West Nile Virus, lymphatic filariasis and avian malaria, over a broad geographical range. As the effectiveness of insecticidal mosquito control methods declines, the need has grown to develop genetic control methods to curb the spread of disease. The piggyBac transposon system - the most widely used genetic transformation tool in insects, including mosquitoes - generates quasi-random insertions of donor DNA into the host genome. However, despite the broad reported species range of piggyBac, previous attempts to use this tool to transform Culex quinquefasciatus mosquitoes have failed. Here we report the first successful transformation of Culex quinquefasciatus with the piggyBac transposon system. Using commercially synthesised piggyBac mRNA as a transposase source, we were able to generate three independent insertions of a ZsGreen fluorescent marker gene, with transformation efficiencies of up to 5%. Through this work, we have expanded the genetic toolkit available for the genetic manipulation of Culex mosquitoes and thus removed a barrier to developing novel genetic control methods in this important disease vector.

A homing rescue gene drive with multiplexed gRNAs reaches high frequency in cage populations but generates functional resistance

28651
Jingheng Chen, Shibo Hou, Ruobing Feng, Xuejiao Xu, Nan Liang, Jackson Champer,  bioRxiv,  2023-12-05 10:59:48.
CRISPR homing gene drive is a potent technology with considerable potential for managing populations of medically and agriculturally significant insects. It induces a bias in the inheritance of the drive allele in progeny, rapidly spreading desired genes throughout the population. Homing drives operate by Cas9 cleavage followed by homology-directed repair, copying the drive allele to the wild-type chromosome. However, resistance alleles formed by end-joining repair pose a significant obstacle to the spread of the drive. To address this challenge, we created a homing drive targeting the essential but haplosufficient hairy gene. Our strategy involves spreading the drive construct through the homing process, eliminating nonfunctional resistance, which are recessive lethal, while rescuing drive-carrying individuals with a recoded version of hairy. This strategy eliminates resistance more slowly than a previous strategy targeting haplolethal genes, but it may be easier to construct in non-model organisms. Our drive inheritance rate was moderate, and multigenerational cage studies showed quick drive spread to 96-97% of the population. However, the drive failed to reach the whole population due to the formation of functional resistance alleles, despite use of four gRNAs, a strategy that previously was successful at preventing functional resistance. Sequencing showed that these alleles had a large deletion and must have utilized an alternate start codon. The resistance allele had a modest fitness advantage over the drive in a cage study, which could prevent long-term persistence of the drive, especially if cargo genes had an additional fitness cost. Thus, revised design strategies targeting more essential regions of a target gene may often be necessary to avoid such functional resistance, even when using multiplexed gRNAs.

Reduced dengue incidence following city-wide wMel Wolbachia mosquito releases throughout three Colombian cities: Interrupted time series analysis and a prospective case-control study

28647
Velez 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

28645
Velez 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.

Meeting Abstracts from the 5th B Chromosome Conference

28643
Anonymous,  BMC Proceedings,  17. 2023-12-05 09:57:11.
During preparations for the 5th B-Chromosome Conference (5BCC), rapid and significant progress was observed in the germ-restricted chromosomes (GRCs) study. GRCs are additional chromosomes found only in germ cells and are eliminated from somatic cells in many avian and dipteran species. Despite their specificity, GRCs share many features of B chromosomes. In view of this intriguing connection, we have decided to extend a special invitation to researchers dedicated to this fascinating topic and to encourage them to participate in the 5BCC. The 5th B Chromosome Conference will be held in Petnica, Serbia, from 14th to 17th October 2023. The conference will take place in five sessions: Constitution, gene composition, Dynamics in populations, B chromosome effects, Segregation behaviour, Origin and evolution. The conference will unite the most prominent chromosome biologists for a stimulating exchange of ideas and insights. We hope that the conference will help establish better collaboration and enable progress in B chromosome research.

Modelling and analysis of periodic impulsive releases of the Nilaparvata lugens infected with wStri-Wolbachia

28638
Xiangjun Dai, Qi Quan and Jianjun Jiao,  Journal of Biological Dynamics,  17:1. 2023-12-04 12:23:12.
In this paper, we formulate a population suppression model and a population replacement model with periodic impulsive releases of Nilaparvata lugens infected with wStri. The conditions for the stability of wild-N.lugens -eradication periodic solution of two systems are obtained by applying the Floquet theorem and comparison theorem. And the sufficient conditions for the persistence in the mean of wild N.lugens are also given. In addition, the sufficient conditions for the extinction and persistence of the wild N.lugens in the subsystem without wLug are also obtained. Finally, we give numerical analysis which shows that increasing the release amount or decreasing the release period are beneficial for controlling the wild N.lugens, and the efficiency of population replacement strategy in controlling wild populations is higher than that of population suppression strategy under the same release conditions.

Food for thought: Assessing the consumer welfare impacts of deploying irreversible, landscape-scale biotechnologies

28628
Michael S. Jones, Zachary S. Brown,  Food Policy,  121. 2023-12-04 10:24:17.
Genetically engineered insects have gained attention as regionally deployed pest control technologies, with substantial applications in agriculture for combatting intractable crop pests and diseases. One potential tool is a ‘gene drive’, using CRISPR-based gene editing. In gene drive, preferentially inherited, engineered traits are spread throughout a geographic area to reduce pest populations or inhibit disease transmission, while also potentially reducing pesticide use and crop prices. But the self-perpetuating nature of gene drives presents a consequence, in that consumers could eventually be limited to only host crops grown in the presence of these genetically engineered insects. In this study, we analyze potential consumer welfare impacts of these technologies using discrete choice experiment data from a representative sample of U.S. adults, examining preferences regarding gene drive use to control spotted wing drosophila in blueberries and Asian citrus psyllid in orange juice (OJ) production. We find smaller average discounts for gene drives versus increased conventional pesticide use or genetically modified crops. Only 27% and 25% of blueberry and OJ consumers, respectively, are estimated to derive disutility from gene drives. However, gene drive disutility for these consumers is so large that elimination of non-drive options from their choice sets results in negative (blueberries) or neutral (OJ) effects to aggregate consumer welfare when weighed against gains to other consumers from reduced prices. Positive welfare effects are recovered by retaining availability of non-gene-drive products. We argue that this type of analysis will be increasingly important as landscape-level biotechnologies are deployed to address challenges to agricultural sustainability.

Manipulating the Destiny of Wild Populations Using CRISPR

28626
Raban R, Marshall JM, Hay BA, Akbari OS.,  Annual Reviews,  57:361-390. 2023-12-04 09:57:57.
Genetic biocontrol aims to suppress or modify populations of species to protect public health, agriculture, and biodiversity. Advancements in genome engineering technologies have fueled a surge in research in this field, with one gene editing technology, CRISPR, leading the charge. This review focuses on the current state of CRISPR technologies for genetic biocontrol of pests and highlights the progress and ongoing challenges of using these approaches.

Wolbachia Transinfection Via Embryonic Microinjection

28593
Zhang, 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.

Efficient sex separation by exploiting differential alternative splicing of a dominant marker in Aedes aegypti

28568
Shih-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.

Effects of different diets on Aedes aegypti adults: improving rearing techniques for sterile insect technique

28541
Aynoanne Leandro Barbosa , Glayciane Costa Gois , Verenna Barros dos Santos , Aline Taiane de Macedo Pinto , Bianca Pires de Castro Andrade , Lucas Barbosa de Souza , Fernanda Hohana Almeida e Sá , Jair Fernandes Virginio and Mário Adriano Ávila Queiroz,  Bulletin of Entomological Research,  2023-11-28 11:17:21.
The aim was to evaluate the effect of different energy diets available in adulthood on the longevity, dispersal capacity and sexual performance of Aedes aegypti produced under a mass-rearing system. To evaluate the effects of diets in relation to the survival of the adult male insects of Ae. aegypti, six treatments were used: sucrose at a concentration of 10%, as a positive control (sack10); starvation, as a negative control (starvation); sucrose at a concentration of 20% associated with 1 g/l of ascorbic acid (sac20vitC); wild honey in a concentration of 10% (honey10); demerara sugar in a 10% concentration (demerara10); and sucrose at a concentration of 20% associated with 1 g/l of ascorbic acid and 0.5 g/l of amino acid proline (sac20vitCPr). Each treatment had 16 cages containing 50 adult males. For the tests of flight ability and propensity to copulation, five treatments were used (saca10; sac20vitC; mel10; demerara10; and sac20vitCPr), with males each for flight ability and females copulated by a single male for copulation propensity. The diet composed of sucrose at a concentration of 20% associated with ascorbic acid, as an antioxidant, improved the survival, flight ability and propensity to copulate in Ae. aegypti males under mass-rearing conditions, and may be useful to enhance the performance of sterile males, thus improving the success of sterile insect technique programmes.

Utility of surveillance data for planning for dengue elimination in Yogyakarta, Indonesia: a scenario-tree modelling approach

28536
Melanie 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.

Engineering mice for female-biased progeny without impacting genetic integrity and litter size

28534
Ido Yosef, Tridib Mahata, Yuhuang Chen, Hadas Bar-Joseph, Ruth Shalgi, Ariel Munitz, Motti Gerlic, Udi Qimron,  bioRxiv,  2023-11-28 10:45:00.
Generating mammalian gametes with a skewed sex ratio has thus far eluded empirical confirmation. The utilization of such genetically engineered organisms would offer the potential to curtail the necessity for culling animals of undesirable sex, mitigate resource wastage, and alleviate superfluous labor burdens. In this study, we introduce a transgenic male mouse lineage, which consistently yields predominantly female progeny (comprising up to 91% of the total offspring). This accomplishment was made possible by integrating a controllable genetic cassette onto the Y chromosome. The cassette encodes dCas9 and RNA guides that selectively silence a spermatid maturation gene. After the separation of X and Y gametes during meiosis, gametes containing an X chromosome develop normally, while those harboring the engineered Y chromosome, subjected to dCas9 silencing of the spermatid maturation gene, do not mature properly. Indeed, some spermatozoa from the transgenic mice exhibit a unique morphology, associated with the absence of the maturation gene. Notably, the resultant female offspring do not inherit the genetically engineered Y chromosome and are thus not genetically modified. Importantly, the litter size of the transgenic mice remains unchanged compared to the wild type. These findings represent a groundbreaking demonstration of genetic engineering’s potential to yield sex-biased litters of full size without compromising genetic integrity, marking a pioneering advancement in this field of study.

Gene drives for the extinction of wild metapopulations

28504
Jason W. Olejarz, Martin A. Nowak,  Journal of Theoretical Biology,  2023-11-27 10:57:31.
Population-suppressing gene drives may be capable of extinguishing wild populations, with proposed applications in conservation, agriculture, and public health. However, unintended and potentially disastrous consequences of release of drive-engineered individuals are extremely difficult to predict. We propose a model for the dynamics of a sex ratio-biasing drive, and using simulations, we show that failure of the suppression drive is often a natural outcome due to stochastic and spatial effects. We further demonstrate rock–paper–scissors dynamics among wild-type, drive-infected, and extinct populations that can persist for arbitrarily long times. Gene drive-mediated extinction of wild populations entails critical complications that lurk far beyond the reach of laboratory-based studies. Our findings help in addressing these challenges.

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