Keywords: Invasive species
CRISPR-Cas9 suppression gene drives for Nile tilapia control: prospects in sub-Saharan African freshwater ecosystems
35509Bobo, E. D., All Life, 19. 2026-03-16 15:14:01.
CRISPR-based suppression gene drives represent a promising tool for managing invasive Nile tilapia (Oreochromis niloticus) populations in sub-Saharan Africa’s freshwater ecosystems. Introduced through aquaculture, Nile tilapia supports livelihoods but also causes severe biodiversity loss. This review explores the technical feasibility of CRISPR-Cas9 suppression gene drives, specifically homing and Driving-Y drive systems, as species-specific, potentially self-sustaining biocontrol strategies. The theoretical effectiveness of these gene drive systems in reducing invasive Nile tilapia and restoring ecological balance is discussed within a precautionary framework. This study addresses the urgent need to protect native tilapia species, which are listed as Critically Endangered, Endangered, and Vulnerable by the IUCN. Gene drives have the potential to reduce invasive populations and restore ecological balance. However, their effectiveness can be compromised by extensive hybridization with native Oreochromis species and resistance evolution in genetically diverse populations. Therefore, the ecological, ethical, and socioeconomic risks of gene drive systems were examined in the context of the Convention on Biological Diversity and Cartagena Protocol. Hence, integrating molecular innovations with strong policy frameworks, stakeholder engagement, and comprehensive risk assessment is essential. CRISPR-Cas9 suppression drives deployment requires careful evaluation across ecological, ethical, and governance contexts to safeguard native ichthyofauna.
Scientists in Australia have created a genetically edited cane toad that gets stuck in the tadpole stage and attacks the plague before it spreads.
35365Noel Budeguer, Click Petróleo e Gás, 2026-01-16 10:59:37.
Australia has begun testing an unusual idea to combat one of the country's most persistent biological invasions: creating tadpoles of the cane toad who have never seen adults. The goal is to cut the problem off at the source, before the animals grow, leave the water, and move into new areas, increasing the impact on native wildlife. The proposal is noteworthy because it shifts the focus of control. Instead of targeting adults who have already spread out, the action targets the point where the population begins, the spawning grounds. The cane toad, a species Rhinella marina, it was introduced in Australia in 1935 and spread rapidly through northern regions. The species adapted quickly, encountered few natural barriers, and came to dominate environments where native animals cannot compete on an equal footing. Over time, the problem ceased to be isolated and became a constant threat to entire ecosystems. The adult stage is what allows the cane toad to move long distances and occupy new territories. The idea behind the project is to prevent this transition, keeping the animal confined to the aquatic environment and reducing the arrival of adults in the natural habitat. In practice, the plan attempts to halt the spread of the pest before it "jumps" out of the water. The technique uses CRISPR Cas9 to alter a point related to the hormonal control of metamorphosis. The target is the production of thyroxine, a hormone that triggers the transformation of the tadpole into an adult frog. Without this signaling, the animal remains in the aquatic phase and does not complete the cycle that would make it an even more aggressive terrestrial invader.
Genetic Allee Effects for Controlling Invasive Populations
35313Louis Nowell Nicolle, Alex Fournier-Level, Charles Robin, et al., Molecular Ecology, 2026-01-02 10:37:23.
Invasive pests threaten food security and devastate ecosystems. A universal problem in their management is that small populations can easily evade detection. This makes identifying new incursions challenging and complicates efforts to eradicate or contain established populations. If newly founded populations exhibited a strong Allee effect, small populations would tend towards extinction and most new incursions would go extinct without the need for detection or intervention. Of course, invasive species rarely exhibit strong Allee effects, but new genetic technologies make it conceivable to impose one. Here we consider how introduction of genetic load can cause a genetic Allee effect that reduces the establishment probability of small founder populations. Using numerical and individual-based modelling, we examine the fate of populations sampled from a larger invasive source population carrying deleterious recessive alleles. Our analysis reveals that the genetic load unmasked by founding can dramatically reduce the establishment probability of small populations across a wide range of parameter space. A sterile mutation effect is more effective than a lethal mutation effect, but X-linkage offers minimal benefit over autosomal inheritance. Although extinction of newly founded populations is a common outcome, it may be challenging to achieve in species with very high reproductive outputs. Distributing deleterious recessive alleles across a large number of loci at low frequencies was more effective than distributing them across fewer loci at higher frequencies. Our findings suggest that driving deleterious recessives into a source population may render it less prone to establish in new areas.
Inhibiting invasive fish reproduction via germ cell xenotransplantation and hybrid lethality
35292Amano, Y., Baba, H., Kishi, D. et al., Scientific Reports, 15. 2025-11-09 17:56:43.
Invasive alien fish constitute a major problem in the conservation of aquatic ecosystems. The most common method of exterminating invasive fish is physical capture by fishing gear; however, it is extremely difficult to eradicate them. Here, we developed a novel methodology to inhibit the reproduction of invasive fish by releasing surrogate males of the same species, which produce sperm of different species, into rivers, allowing them to produce lethal hybrids through natural spawning. This study focused on rainbow trout, an invasive fish that negatively impacts ecosystems worldwide. Since rainbow trout × brown trout hybrids are lethal, surrogate rainbow trout producing brown trout sperm were created by germline stem cell transplantation. Releasing the surrogate males into an experimental river inhabited by wild-type rainbow trout females revealed that they naturally mated and produced lethal hybrid offspring. This is a novel and powerful methodology for eradicating invasive fish.
Fruit fly tests in Greece target invasive species threat
35161Vassilis Kyriakoulis, Phys.org, 2025-09-15 15:24:50.
In a small persimmon orchard in northern Greece, scientists carefully open paper bags to release thousands of flies, in an experiment aimed at blunting the destructive impact of invasive new species. The insects are sterile male Mediterranean fruit flies (Ceratitis capitata), a pest that annually causes significant damage to crops in Naousa, where a large proportion of Greece's prominent export, the peach, is produced. But the project is ultimately aimed at curbing an even greater threat: fruit fly species from Asia, which have begun to make their appearance in southeastern Europe as climate change increases local temperatures. The four-year, EU-funded project titled REACT brings together researchers from 12 different countries including the UK, Israel and South Africa. The program has a budget of 6.65 million euros ($7.8 million). "Our approach is to locally eradicate Mediterranean fruit fly populations and then apply this knowledge to other species of interest, such as the oriental fruit fly and the peach fruit fly," said project participant Nikos Papadopoulos, a professor of Applied Entomology at the University of Thessaly. The male flies are grown at the University of Patras and are fed a bacterial supplement that makes them more active, resilient, and competitive, said George Tsiamis, the university's Laboratory of Microbiology Systems director, during a media tour organized in Naousa by the research team.
Are we winning the war on cane toads?
35089Tom Gurn, Particle, 2025-08-28 19:10:42.
In 1935, a species known as the giant neotropical toad (Rhinella marina) was introduced to Australia. Scientists hoped these amphibians would control native cane beetles, but cane toads quickly colonised the country and had no discernible impact on beetle populations. Many different methods are being tested to remove these warty beasts, including a toad containment zone and turning the toads into sausages. Now, almost a century later, scientists believe they have finally stumbled across a potential solution to one of the worst invasive species ever. Will clever gene-editing techniques finally rid this continent of the dreaded cane toad? Professor Emeritus Rick Shine led the team behind the new idea, based on CRISPR gene-editing techniques. “We seem to have found a chink in the toads’ armour,” says Rick. “If we could only stop their metamorphosing, we could have these eternal tadpoles,” he says. Searching for collaborators to test this cunning plan, Rick happened across molecular biologist Dr Maciej Masielko, who was immediately struck by the beauty of the idea. “We know enough about the biochemistry of metamorphosis to know what we would need to do,” says Maciej. “Like using CRISPR-Cas9 to delete a part of the cane toad’s DNA.”
Coproducing a Technology Readiness Level framework for non-persistent genetic biocontrol of aquatic invasive species
34984Julie Badger, Rex Alirigia, Isabel Ameli, et al, Journal of Environmental Management, 391. 2025-07-24 10:00:28.
Developing and implementing novel pest control technologies requires coordination and communication between technology developers, funding agencies, federal and state regulators, and early technology adopters. Efficient communication is particularly important for first-in-class technologies. Misunderstandings or lack of communication may hinder social engagement, jeopardize regulatory approval, decrease utility of the technology, deter public adoption, or compromise risk mitigation approaches. We, a team of diverse stakeholders in aquatic invasive species (AIS) control, here propose a shared language for discussing the development of non-persistent genetic biocontrol methods. Specifically, we adapted the existing Technology Readiness Level framework to apply to the development of non-persistent genetic biocontrol for invasive Cyprinus carpio (common carp) as a model case. The result of this effort is a tool for designing responsible technology development of a promising new class of pest management tools.
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.
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.
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.
Progress made for blackchin tilapia control in Thailand
34535The Fish Site, 2025-02-21 11:50:45.
Despite tilapia being one of the most widely farmed fish in the global aquaculture industry, invasive populations of the blackchin tilapia - a cichlid native to West Africa - have been devastating the productivity of aquaculture operations throughout Thailand. However, a multi-stakeholder effort led by the country's Department of Fisheries has reported progress towards controlling this invasive species, turning an environmental challenge into a pathway for sustainable development and local economic growth. Forming part of a five-point government strategy to address the ecological challenges posed by invasive species, the Department of Fisheries has developed a specially engineered strain known as Blackchin Tilapia 4n - a genetically modified variant designed to inhibit reproduction. The experimental strain has been released at experimental sites this month to evaluate its effectiveness in reducing the invasive fish population. Simultaneously, another project is specifically geared towards assisting aquaculture producers. The Seabass Fund for Farmers assists farmers in reducing costs by introducing natural predators into aquaculture ponds, effectively managing the blackchin tilapia population. This programme was established by the Phetchaburi Provincial Fisheries Office to support small-scale farmers with revolving funds for purchasing seabass fingerlings, providing a sustainable solution for shrimp, fish, and crab farmers operating in semi-natural systems to control and reduce populations of the invasive cichlid. In addition to direct eradication efforts, the promotion of blackchin tilapia products, such as foods and feeds, is being used to encourage consumption of the fish, driving local economic growth. These initiatives have been implemented by Charoen Pokphand Foods throughout 2024, including the purchase of 2 million kilograms of Blackchin tilapia for fishmeal production. Charoen Pokphand has also extended assistance to fishing activities aimed at blackchin tilapia removal by supplying fishing equipment and necessary materials to participants. If successful, these programmes for the control of blackchin tilapia populations in Thailand could serve as a model for governmental and private-sector cooperation for environmental solutions and local economic development.
Why are gene drive technologies being considered to help restore biodiversity on islands?
32530Outreach Network for Gene Drive Research, 2024-10-15 11:55:45.
Researchers have been studying how to harness gene drives to solve some of society’s most intractable problems for a long time. Public health and ecosystem conservation are two of the main areas where research has focused, although other uses are also possible.
Fluorescent-based sex-separation technique in major invasive crop pest, Drosophila suzukii
32544Junru Liu, Danny Rayes, Minzhe Yang, Omar S. Akbari, bioRxiv, 2024-10-09 12:30:05.
Insect population biocontrol methods such as the sterile insect technique (SIT), represent promising alternatives to traditional pesticide-based control applications. To use these strategies efficiently requires scalable sex separation techniques which are currently lacking in Drosophila suzukii, a prominent crop pest species. Having previously characterized a fluorescence-based sex-sorting technique in other pests, termed SEPARATOR (Sexing Element Produced by Alternative RNA-splicing of A Transgenic Observable Reporter), here we explore its potential applicability to Drosophila suzukii. Here, we engineer several strains of Drosophila suzukii encoding SEPARATOR constructs that allow for efficient sex selection in early larval stages.
New genetic-editing technique to alter the traits and fates of wild populations
31454Lori Dajose, CalTech, 2024-09-03 21:38:08.
Gene drives are a common technology used to insert a novel gene into a population—for example, to make mosquitos resistant to malaria. They can also be used to modify existing genes, such as making herbicide-resistant weeds susceptible to herbicides once again or even to suppress invasive populations. However, gene drives often face social concerns and regulatory challenges because they involve the spread of transgenes (genes that have been transferred and integrated into an organism's DNA) to high frequency. The new technique, called an Allele Sail, uses the CRISPR/Cas9 genome-editing technology to introduce a targeted "editor" into a population at low frequency. This editor itself does not increase in frequency as organisms reproduce, however, any organism that mates with an editor-carrying organism will become altered at the genomic position targeted by the editor, passing the altered version (called an allele) of the gene down to its own offspring. In this way, the technique mimics the natural genetic process of passing down genes and mutations, and can be used in a wider range of species than traditional gene drive approaches. "Imagine you have a big room of bouncing balls, most of them white but a few are red," says Bruce Hay, professor of biology and biological engineering. "Any time a red ball—the editor—bumps into a white ball, it turns the white ball pink—the edit. As the balls bounce around, over time, more and more of them turn pink."
Gene Drives: A Powerful and Controversial Genetic Technology
31456Biomedical and Life Sciences Simplified, YouTube, 2024-09-03 09:01:56.
Gene drives represent a powerful yet controversial genetic technique that challenges traditional Mendelian inheritance. By introducing self-propagating changes into an organism's genome, gene drives can ensure that a specific mutation becomes homozygous in offspring, effectively spreading it through a population. This powerful tool has potential applications in eradicating mosquito-borne diseases like malaria and Zika, combating drug-resistant pathogens, and controlling invasive species. But how exactly does it work? This video breaks down the science behind gene drives and the role of CRISPR technology.
What are gene drives, and how can they help eradicate invasive species in Australia?
28563Dr. Ellen Cottingham, ABC News (Australia Broadcasting Corporation), 2023-11-29 13:52:33.
The impact of feral cats and other invasive species is felt across Australia. Not only do they threaten native species, but they can also spread diseases to humans and livestock. Invasive species are estimated to cost Australia an eye-watering $25 billion annually, while the global cost is a staggering $423 billion. Feral cats are everywhere — the nation is home to up to 6.3 million of them, and they are responsible for killing millions of native mammals, reptiles, and birds each day. Minister for the Environment and Water Tanya Plibersek recently declared "war on feral cats", announcing plans involving cat curfews, desexing regulations, and caps on cat numbers in homes. But what can we do about the millions of feral cats already wreaking havoc across Australia? And what about other pests such as foxes, rabbits, cane toads, carp, pigs, deer, or goats? One technique with the potential to help fight not just cats but all invasive species is called a "gene drive".
Assessing the suitability of YY males and ZZ females as an invasive species population control method across life histories
28170R. A. Erickson, H. M. Thompson, S. A. Kageyama, G. M. Andriacchi, A. R. Cupp, R. Patiño and J. J. Amberg, Biological Invasions, 25:3737-3751. 2023-08-12 12:16:15.
Natural resource managers use tools to control invasive species. In theory, stocking YY males or ZZ females would allow managers to skew sex ratios until populations collapse. In combination with other suppression methods, such as removal, this approach could be incorporated into Integrated Pest Management plans. For example, fishery managers have stocked YY males to control isolated non-native brook trout (Salvelinus fontinalis) populations. However, life histories and demographic factors (e.g., lifespans) vary across species and could affect the feasibility of skewing sex ratios as an effective control strategy for a given population. Likewise, some species may have sex determinations that do not allow population control through sex-skewing methods. We compared five representative aquatic invasive species with global invasion ranges for potential control by skewing the sex ratio through closed population simulations: red swamp crayfish (Procambarus clarkii), zebra mussels (Dreissena polymorpha), lake trout (Salvelinus namaycush), silver carp (Hypophthalmichthys molitrix), and Nile tilapia (Oreochromis niloticus). We determined that Nile tilapia, red swamp crayfish, and zebra mussels would be the most suitable to control through skewing the sex ratio assuming appropriate sex determination exists in the species. Lake trout could be eliminated by stocking YY males but would require either long stocking periods or high stocking numbers because of the long lifespan of the species. Silver carp populations were more difficult to crash because they live longer and produce many recruits. Broadly, these patterns demonstrated that short lived species lend themselves to control by skewing the sex ratio.
Effects of γ-Irradiation on Mating Behavior of Red Palm Weevil, Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Dryophthoridae)
27600M. Cristofaro, C. Fornari, F. Mariani, A. Cemmi, M. Guedj, M. L. Ben Jamaa, M. Msaad Guerfali, E. Tabone, R. Castellana, R. Sasso and S. Musmeci, Insects, 14. 2023-07-24 07:00:32.
Red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier 1790) is a highly invasive species originating from Southeast Asia and Melanesia. Over the past 30 years, this alien pest has spread extensively in the Middle East and the Mediterranean basin. Its endophagous larvae feed on various palm species, causing significant damage that leads to the death of palm trees. Controlling RPW infestations is challenging due to their gregarious nature and the lack of detectable early symptoms. Systemic insecticides are effective means of control, but their use in urban areas is prohibited and resistance can develop. Considering alternative options with minimal environmental impact, the Sterile Insect Technique (SIT) has been explored. Previous research has shown that male RPWs irradiated at 80 Gy or higher achieve full sterility. This study aimed to investigate in laboratory conditions whether RPW sterile males (irradiated at 60 and 80 Gy) could compete sexually with non-irradiate males. Laboratory bio-assays under both no-choice and choice conditions assessed sexual performance in terms of number of matings, mating duration and time elapsed until the first mating. The results confirmed that irradiation does not negatively affect the mating performance of sterile males, demonstrating their ability to compete successfully with non-irradiated males in both experimental setups.
The attitudes of young adults towards mammalian predator control and Predator Free 2050 in Aotearoa New Zealand
26186L. Dickie and F. Medvecky, Australasian Journal of Environmental Management, 2023-06-09 12:31:11.
Predator Free 2050 (PF2050) is an ambitious goal that aims to remove three types of invasive mammals from New Zealand by 2050. It will require a significant amount of funding, research, and support. Young adults will have an important role to play for this programme to be successful. Therefore, understanding the awareness and attitudes of young adults towards PF2050, and predator control, is an essential consideration. A survey of 1479 18- to 24-year-olds was conducted in 2017. The results showed that a higher percentage of young adults than members of the broader public view the small, introduced mammals as threats to New Zealand’s environment. Furthermore, this study highlights support for the control of feral, stray, and domestic cats. More focused research on attitudes towards cats is recommended to gauge which control methods are approved of by young adults. Indeed, methods appear to be a key factor to young adults supporting PF2050. The aerial distribution of poison was largely viewed negatively, and moderate concern was expressed about the targeted animal’s welfare. Interestingly, young adults appeared to be open to the use of gene editing and gene drive, although they expressed caution. Targeted communication towards young adults on toxins and genetic methods is recommended. © 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
GeneConvene Global Collaborative Webinar Series | Emerging Gene Drive Systems 2023
24769David O'Brochta, 2023-02-22 15:50:48.
Gene drive systems are being engineered in the laboratory and in some cases shown to be effective at rapidly altering target-gene frequencies in experimental populations. Much of this foundational work has been conducted in insects in the laboratory. This webinar series will focus on emerging potential applications of gene drive technology in a wide variety of organisms. These webinars are intended to inform audiences of the rationale for these development efforts, the current state of research and development and outstanding challenges.
Social justice environmental activists move to block gene editing to control invasive species and promote biodiversity. Here’s why they’re misguided
24701S. Smyth, Genetic Literacy Project, 2023-02-07 12:46:02.
Control of invasive species has been extremely difficult with eradication virtually impossible. To control invasive plant species, chemicals are commonly used while in some instances removal of plants by hand, as Shiva advocates, is undertaken. Efforts to control invasive animals include poisoning and shooting. Needless to say, these ‘control techniques’ are inefficient and often harmful to the applicators. Advances in genetics potentially offer new solutions, using gene editing technology to create sterile populations. Sterility is a natural trait in mammals, which can be induced into invasive animals as a means of population control. Invasive pests can be captured, gene-edited to confer sterility in future generations and then released back into the wild. The offspring will gradually without the use of chemicals or hand labor contribute to reduced populations. Applying gene editing technologies is not an instantaneous solution, but they may be part of a long-term strategy.
Assessing potential hybridization between a hypothetical gene drive-modified Drosophila suzukii and nontarget Drosophila species
24610S. Wolf, J. Collatz, J. Enkerli, F. Widmer and J. Romeis, Risk Analysis, 2023-01-24 09:02:35.
Genetically engineered gene drives (geGD) are potentially powerful tools for suppressing or even eradicating populations of pest insects. Before living geGD insects can be released into the environment, they must pass an environmental risk assessment to ensure that their release will not cause unacceptable harm to non-targeted entities of the environment. A key research question concerns the likelihood that nontarget species will acquire the functional GD elements; such acquisition could lead to reduced abundance or loss of those species and to a disruption of the ecosystem services they provide. The main route for gene flow is through hybridization between the geGD insect strain and closely related species that co-occur in the area of release and its expected dispersal. Using the invasive spotted-wing drosophila, Drosophila suzukii, as a case study, we provide a generally applicable strategy on how a combination of interspecific hybridization experiments, behavioral observations, and molecular genetic analyses can be used to assess the potential for hybridization.
New CRISPR tech makes it possible to wipe out invasive mice
241812022-12-11 11:12:20.
East Maui project hopes mosquito v. mosquito mating battle will save endangered birds
24173K. Cerizo, MAUINOW, 2022-12-11 11:03:34.
A natural gene drive could steer invasive rodents on islands to extinction
24129B. Brookshire, ScienceNews, 2022-12-05 09:12:58.
In the battle against the invasive house mouse on islands, scientists are using the rodent’s own genes against it. With the right tweaks, introducing a few hundred genetically altered mice could drive an island’s invasive mouse population to extinction in about 25 years, researchers report in the Nov. 15 Proceedings of the National Academy of Sciences. The trick is adding the changes to a section of mouse DNA that gets inherited far more often than it should. Scientists have been creating similar extra-inheritable genes — called gene drives — in the lab. The chunks are designed to get passed on to most or all of an animal’s offspring instead of the usual half, and make those offspring infertile in the bargain. Scientists have used gene drives to reduce populations of mosquitoes and fruit flies (SN: 12/17/18). But mammals are a different story. Scientists have previously synthesized a gene drive that gets passed on in mice about 80 percent of the time (SN: 1/23/19). But the drive isn’t strong enough to stop a population quickly. Luckily, nature has it handled. A haplotype is a naturally occurring group of genes that gets passed on as a unit during replication. The genome of the house mouse (Mus musculus) has a particular haplotype, called the t haplotype, that gets passed on to offspring more than 95 percent of the time, instead of the typical 50 percent.
Should NZ use contentious gene tech in our war on pests?
24032J. Morton, NZ Herald, 2022-11-27 09:45:02.
Gene-altering technology could offer “breakthrough opportunities” for saving our pest-threatened species, a new future-scoping report says, but there’d be some tricky issues to address before it’d be a realistic option. Scientists have already been exploring how these contentious tools - among several areas canvassed in a new future-focused briefing by the Department of Conservation and Land Information New Zealand - might aid our ongoing war on pest predators. But it’s doubtful that would happen anytime soon, given the tech isn’t yet ready, and the Government has little appetite toward making law changes that’d likely be needed to unleash it in our environment. The briefing, just put out for public feedback, explained how gene-editing tools like Crispr-Cas9 could be used to change particular genes or introduce new traits.
Why we need to talk about ‘gene-drive’ grey squirrels
23778Anonymous, University of Exeter, 2022-10-17 07:04:37.
Would the best way of controlling the UK’s rampant grey squirrel population be to spread genetic changes throughout the species? A new research film, to be shown next month at Exeter Phoenix, sees scientists, conservation and wildlife experts debate the use of emergent ‘gene-drive’ technology in grey squirrels. The film Should we create gene drive grey squirrels?, written and produced by Sarah Hartley, a Professor in Technology Governance at the University of Exeter Business School, and independent film-maker Tom Law, documents the introduction into the UK of grey squirrels at the turn of the 20th Century and how their burgeoning population has contributed to the demise of the UK’s native red squirrel, which is now mainly found in Scotland. It presents the reasons why some people argue it would be better to limit the grey squirrel population, including the fact that they carry and spread squirrel pox, a virus fatal to red squirrels which can devastate entire populations.
How to Exterminate the Invaders: Playing Dangerously with the Pandora’s Box of Genetic Engineering
23508Spivey, Czechia Posts English, 2022-09-01 19:35:59.
Man has dragged alien species to new continents, sometimes inadvertently and often intentionally. That’s how she got from America to Europe Musk Muskrat (Ondatra zibethicus) whose nutria (Myocastor coypus). He traveled in the opposite direction across the Atlantic, for example common starling (Sturnus vulgaris) or field lark (Alauda arvensis). Sometimes the transoceanic import passed without consequences, other times it started a natural disaster. Undoubtedly, the most famous destructive invasion was caused by the deliberate importation of the wild rabbit (Oryctolagus cuniculus) to Australia.
Genetically-enhanced biocontrols can help fight large invasive mammals
23157Pensoft Publishers, Science Daily, 2022-07-08 09:49:27.
A team of researchers from the University of Adelaide developed a mathematical model able to simulate the impact of gene drives on mammal populations at a landscape scale. Published in the open-access NeoBiotajournal, their study is the first to estimate the time it would take to eradicate long-lived alien mammals. Using CRISPR-Cas9 technology, the simulated gene drive relies on "molecular scissors" inserted into the Y-chromosome that target and slice up the X-chromosome at the right time during meiosis, so that only Y-chromosome carrying sperms are functional and can successfully fertilize the egg. In this way, the drive carrying males should only produce sons that also carry the molecular scissors on their Y-chromosome. Over multiple generations, females will become rarer and produce fewer offspring; as a result, the population size will fall.
Scalability of genetic biocontrols for eradicating invasive alien mammals
23159A. Birand, P. Cassey, J. V. Ross, P. Q. Thomas and T. A. A. Prowse, NeoBiota, 74:93-103. 2022-07-07 09:59:20.
CRISPR-based gene drives offer novel solutions for controlling invasive alien species, which could ultimately extend eradication efforts to continental scales. Gene drives for suppressing invasive alien vertebrates are now under development. Using a landscape-scale individual-based model, we present the first estimates of times to eradication for long-lived alien mammals. We show that demography and life-history traits interact to determine the scalability of gene drives for vertebrate pest eradication. Notably, optimism around eradicating smaller-bodied pests (rodents and rabbits) with gene-drive technologies does not easily translate into eradication of larger-bodied alien species (cats and foxes).
The suppressive potential of a gene drive in populations of invasive social wasps is currently limited
23091A. B. Meiborg, N. R. Faber, B. A. Taylor, B. A. Harpur and G. Gorjanc, bioRxiv, 2022.06.27.497711. 2022-06-30 07:33:43.
Social insects are very successful invasive species, and the continued increase of global trade and transportation has exacerbated this problem. The yellow-legged hornet, Vespa velutina nigrithorax (henceforth Asian hornet), is drastically expanding its range in Western Europe. As an apex insect predator, this hornet poses a serious threat to the honey bee industry and endemic pollinators. Current suppression methods have proven too inefficient and expensive to limit its spread. Gene drives might be an effective tool to control this species, but their use has not yet been thoroughly investigated in social insects. Here, we built a model that matches the hornet’s life history and modelled the effect of different gene drive scenarios on an established invasive population. To test the broader applicability and sensitivity of the model, we also incorporated the invasive European paper wasp Polistes dominula. We find that although a gene drive can spread through a social wasp population, it can only do so under stringent gene drive-specific conditions. The main issue is that the large number of offspring that social wasp colonies produce guarantees that, even with very limited formation of resistance alleles, such alleles will quickly spread and rescue the population. Furthermore, we find that only a gene drive targeting female fertility is promising for population control due to the haplodiploidy of social insects. Nevertheless, continued improvements in gene drive technology may make it a promising method for the control of invasive social insects.Competing Interest StatementThe authors have declared no competing interest.
Generation of Gene Drive Mice for Invasive Pest Population Suppression
22890M. D. Bunting, C. Pfitzner, L. Gierus, M. White, S. Piltz and P. Q. Thomas, Applications of Genome Modulation and Editing, 2022-06-14 06:00:54.
Gene drives are genetic elements that are transmitted to greater than 50% of offspring and have potential for population modification or suppression. While gene drives are known to occur naturally, the recent emergence of CRISPR-Cas9 genome-editing technology has enabled generation of synthetic gene drives in a range of organisms including mosquitos, flies, and yeast. For example, studies in Anopheles mosquitos have demonstrated >95% transmission of CRISPR-engineered gene drive constructs, providing a possible strategy for malaria control. Recently published studies have also indicated that it may be possible to develop gene drive technology in invasive rodents such as mice. Here, we discuss the prospects for gene drive development in mice, including synthetic “homing drive” and X-shredder strategies as well as modifications of the naturally occurring t haplotype. We also provide detailed protocols for generation of gene drive mice through incorporation of plasmid-based transgenes in a targeted and non-targeted manner. Importantly, these protocols can be used for generating transgenic mice for any project that requires insertion of kilobase-scale transgenes such as knock-in of fluorescent reporters, gene swaps, overexpression/ectopic expression studies, and conditional “floxed” alleles.
Wolbachia 16S rRNA haplotypes detected in wild Anopheles stephensi in eastern Ethiopia
22568E. Waymire, S. Duddu, S. Yared, D. Getachew, D. Dengela, S. R. Bordenstein, M. Balkew, S. Zohdy, S. R. Irish and T. E. Carter, Parasites and Vectors, 15:178. 2022-05-24 08:50:15.
About two out of three Ethiopians are at risk of malaria, a disease caused by the parasites Plasmodium falciparum and Plasmodium vivax. Anopheles stephensi, an invasive vector typically found in South Asia and the Middle East, was recently found to be distributed across eastern and central Ethiopia and is capable of transmitting both P. falciparum and P. vivax. The detection of this vector in the Horn of Africa (HOA) coupled with widespread insecticide resistance requires that new methods of vector control be investigated in order to control the spread of malaria. Wolbachia, a naturally occurring endosymbiotic bacterium of mosquitoes, has been identified as a potential vector control tool that can be explored for the control of malaria transmission. Wolbachia could be used to control the mosquito population through suppression or potentially decrease malaria transmission through population replacement. However, the presence of Wolbachia in wild An. stephensi in eastern Ethiopia is unknown. This study aimed to identify the presence and diversity of Wolbachia in An. stephensi across eastern Ethiopia.
What role can gene editing play in predator control? And are we ready to accept it?
22727K. Green, Stuff, 2022-05-16 08:07:14.
The once-forbidden concept of gene editing for predator control is back on the table after two projects receivedGovernment funding. Despite advances overseas, experts are worried research in New Zealand will never make it out of the lab, with no plans to change current restrictive laws. Appetite for gene editing has always been low among the New Zealand public. In 1999, 20,000 people protested in Auckland alone, marching down Auckland’s Queen St calling for a ban on genetically engineered crops. Gene editing joined nuclear-free as a hallmark of clean, green New Zealand. However last month, the crown entity responsible for pest control, Predator Free 2050, announced investment of $6.7 million into research projects, including $2.25m to investigate whether recent overseas advances in producing mice of only one sex could be adapted for rats, and $200,000 to explore stoat breeding genetics, and whether that could be used for control.
Bayesian network-based risk assessment of synthetic biology: Simulating CRISPR-Cas9 gene drive dynamics in invasive rodent management
22516E. A. Brown, S. R. Eikenbary and W. G. Landis, Risk Analysis, 2022-05-14 07:22:34.
Gene drive technology has been proposed to control invasive rodent populations as an alternative to rodenticides. However, this approach has not undergone risk assessment that meets criteria established by Gene Drives on the Horizon, a 2016 report by the National Academies of Sciences, Engineering, and Medicine. To conduct a risk assessment of gene drives, we employed the Bayesian network-relative risk model to calculate the risk of mouse eradication on Southeast Farallon Island using a CRISPR-Cas9 homing gene drive construct. We modified and implemented the R-based model "MGDrivE" to simulate and compare 60 management strategies for gene drive rodent management. These scenarios spanned four gene drive mouse release schemes, three gene drive homing rates, three levels of supplemental rodenticide dose, and two timings of rodenticide application relative to gene drive release. Simulation results showed that applying a supplemental rodenticide simultaneously with gene drive mouse deployment resulted in faster eradication of the island mouse population. Gene drive homing rate had the highest influence on the overall probability of successful eradication, as increased gene drive accuracy reduces the likelihood of mice developing resistance to the CRISPR-Cas9 homing mechanism.
Aquatic invasive species specialists’ perceptions on the importance of genetic tools and concepts to inform management
22482T. A. Bernos, K. M. Jeffries and N. E. Mandrak, Biological Invasions, 24:1863-1879. 2022-05-14 07:09:36.
Perceptions related to the importance of genetic research influence the mobilization of genetic tools and concepts to inform conservation actions. Research characteristics, stakeholders’ perspectives, knowledge, and social linkages with geneticists influence the outcome of genetic information for management practices. We surveyed a broad range of aquatic invasive species (AIS) specialists whose opinions, perspectives, and decisions influence AIS decision-making. We assessed perceptions related to the importance of genetic tools and concepts, as well as the appropriateness of genetic biocontrol, and tested whether their expertise, background, and experience influenced perceptions in a predictable way. While perceptions towards genetic tools and concepts were generally heterogeneous, there was a high consensus (84%) related to the importance of eDNA. Most predictors were weakly correlated with importance ratings. Specialists’ genetic knowledge was the strongest predictor of higher importance ratings: the odds of AIS specialists giving higher ratings increased by up to 1.5-fold with increasing genetic knowledge. When evaluating the appropriateness of genetic biocontrol, level of support was lower for approaches based on gene editing (58%) than those relying on traditional hatchery techniques (70%). Support for gene editing varied by geographic location and with specialists’ knowledge of genetics and AIS management. These findings suggest that perceptions towards genetic research vary between genetic tools and concepts and are shaped by the interplay of individual’s values, expertise, experience, and background. To collaborate more effectively, genetic scientists must understand the extent of genetic knowledge of their AIS management partners and recognize that their conceptions of the conservation genetics research-practice space may vary.
The principles driving gene drives for conservation
22295S. Hartley, R. Taitingfong and P. Fidelman, Environmental Science and Policy, 135:36-45. 2022-05-04 08:30:40.
Gene drive technology is an emerging biotechnology with the potential to address some of the most intractable global biodiversity conservation issues. Scientists are exploring potential gene drive applications for managing invasive species and building resilience in keystone species threatened by climate change. The possibility to use gene drive for these conservation purposes has triggered significant interest in how to govern its development and eventual applications. This includes a plethora of documents prescribing governance principles, which can be a sensible response to the governance gap created by emerging technologies and help shore up legitimacy. We conducted qualitative documentary analysis to examine the range and substance of principles emerging in the governance of conservation gene drive. Such analysis aimed to better understand the aspirations guiding these applications and how scientists and other experts imagine their responsibility in this field. We found a collection of recommendations and prescriptions that could be organised into a set of seven emerging principles intended to shape the governance of gene drive in conservation: broad and empowered engagement; public acceptance; decision-making informed by broad ranging considerations, state and international collaboration; ethical frameworks; diverse expertise; and responsible self-regulation by developers. We lay bare these emergent principles, analyzing the way in which they are valued, prioritized, and their strengths and weaknesses. By identifying these prescriptive principles, stakeholders can further interrogate their merits and shortcomings and identify more concrete ways that governance frameworks might embody them.
Quality Control Methods for Aedes albopictus Sterile Male Transportation
20392G. D. Mastronikolos, A. Kapranas, G. K. Balatsos, C. Ioannou, D. P. Papachristos, P. G. Milonas, A. Puggioli, I. Pajović, D. Petrić, R. Bellini, A. Michaelakis and N. T. Papadopoulos, Insects, 2022-02-09 09:27:23.
Genetic based mosquito control methods have been gaining ground in recent years for their potential to achieve effective suppression or replacement of vector populations without hampering environments or causing any public health risk. These methods require the mass rearing of the target species in large facilities sized to produce millions of sterile males, as already well established for a number of insects of agricultural importance. Assessing the performance of released males in Sterile Insect Technique (SIT) control programs is of the utmost importance for the success of the operation. Besides the negative effects of mass rearing and sterilization, the handling of sterilized insects and shipment to distant areas may also negatively impact the quality of sterilized males. The aim of the current study was to design and executive quality control (QC) tests for sterilized Aedes albopictus (Asian tiger mosquito) males delivered by air shipment from the mass production facility located in Italy to Greece and Montenegro field release sites. Mass reared mosquito strains were based on biological materials received from Italy, Greece and Montenegro. Tests conducted at the mass rearing facility before transportation revealed a rather high residual female contamination following mechanical sex separation (approximately 1.5% females, regardless of the mosquito strain). Irradiated males of all three mosquito strains induced high levels of sterility to females. Shipment lasting approximately 24 h resulted in approximately 15% mortality, while when shipment lasted nearly two days this increased to almost 40%. The flight ability of sterilized males following one day transportation time was satisfactory (over 60%). The response of sterile males to food and water starvation was comparable and slightly lower than that of wild non-transported males. Longevity of sterile males was shorter than that of wild counterparts and it seems it was not affected by mating to wild females. Both mating propensity and mating competitiveness for wild virgin females was higher for the wild, control males compared to the sterile, transported ones. Overall, the performance of sterile male Ae. albopictus delivered from the mass rearing facility of Italy to Greece in approximately 24 h was satisfactory. Transportation lasting two days or longer incurred detrimental effects on males, which called into question the outcome of the SIT release programs. In conclusion, our results demonstrate the need of quality control procedures, especially when sterile male production facilities are not near to the releasing point. Transportation could be a serious drawback for the implementation of Sterile Insect Releases and, consequently, it is important to establish an efficient and fast transportation of sterilized males in advance.
Monitoring Needs for Gene Drive Mosquito Projects: Lessons From Vector Control Field Trials and Invasive Species
20177G. Rašić, N. F. Lobo, E. H. Jeffrey Gutiérrez, C. H. Sánchez and J. M. Marshall, Frontiers in Genetics, 12:780327. 2022-01-25 09:18:49.
As gene drive mosquito projects advance from contained laboratory testing to semi-field testing and small-scale field trials, there is a need to assess monitoring requirements to: i) assist with the effective introduction of the gene drive system at field sites, and ii) detect unintended spread of gene drive mosquitoes beyond trial sites, or resistance mechanisms and non-functional effector genes that spread within trial and intervention sites. This is of particular importance for non-localized gene drive projects, as the potential scale of intervention means that monitoring is expected to be more costly than research, development and deployment. Regarding monitoring needs for population replacement systems, lessons may be learned from experiences with Wolbachia-infected mosquitoes, and for population suppression systems, from experiences with releases of genetically sterile male mosquitoes. For population suppression systems, assessing monitoring requirements for tracking population size and detecting rare resistant alleles are priorities, while for population replacement systems, allele frequencies must be tracked, and pressing concerns include detection of gene drive alleles with non-functional effector genes, and resistance of pathogens to functional effector genes. For spread to unintended areas, open questions relate to the optimal density and placement of traps and frequency of sampling in order to detect gene drive alleles, drive-resistant alleles or non-functional effector genes while they can still be effectively managed. Invasive species management programs face similar questions, and lessons may be learned from these experiences. We explore these monitoring needs for gene drive mosquito projects progressing through the phases of pre-release, release and post-release.
Track New Zealand’s Bid to Take Back Nature
20169K. Peek, Scientific American, 2022-01-25 09:05:48.
A thousand years ago the islands that today form New Zealand were riotously wild. Birds, reptiles and invertebrates flourished in lush forests hundreds of miles from any other landmass. Māori settlers in the 1200s brought Polynesian rats for food, and together the humans and the rodents began to shift the ecological balance. Native species started to go extinct. Enter European ships, bearing new carnivores: more aggressive rat species, plus mice, stoats, and others. These ground-based predators hunted differently from the falcons and other aerial threats New Zealand wildlife had evolved with. Native birds that slept in burrows made easy prey for prowling mammals. Invasive predator populations exploded, devastating native wildlife. But in the past 60 years humans have intervened to help old New Zealand ecosystems claw their way back. First, a single five-acre (two-hectare) islet called Maria Island (Ruapuke in Māori) was declared rat-free by ecologists in 1964, five years after volunteers set poisoned bait. It was a special case. The white-faced storm petrels at risk there were especially charismatic—they appear to walk on water—and easily gained public support. The ample baiting effort also got particularly lucky with its placement, ecologists say. Nevertheless, the serendipitous success kicked off decades of eradication efforts.
Could we delete diseases passed down through our DNA?
20278E. Rayne, SYFY, 2022-01-23 11:33:23.
What has now been proven possible was once the stuff of science fiction dreams. CRISPR has shown it can successfully edit out detrimental genetic conditions before they are inherited — which could mean the beginning of the end for hereditary diseases. It could also help obliterate invasive species from ecosystems under attack. Imagine if gene editing could delete conditions you never asked to be born with while getting rid of the cane toad invasion in Australia. CRISPR-Cas9 has been able to successfully edit DNA again and again, but it’s never done anything like this. Kind of like DNA autocorrecting itself, the editing needs to make deletion in a cell happen during a certain phase of meiosis. Researcher Kimberly Cooper of UC San Diego, who coauthored a study recently published in PLOS Biology, figured out exactly when to get to that meiotic window and how to control which copies of genes are handed down to the next generation.
Scientists expand CRISPR-Cas9 genetic inheritance control in mammals
20038M. Aguilera, Phys Org, 2022-01-12 09:43:07.
Led by graduate student Alexander Weitzel, Grunwald, Cooper and their colleagues have now succeeded in developing CRISPR-Cas9 inheritance control in male mice by shifting the gene editing window to more closely match the timing of meiosis in both sexes. Their results were published December 23, 2021 in the journal PLOS Biology. The achievement advances the prospects of scientists being able to use genetic editing for new laboratory models in an array of research pursuits, from investigations of human disease to therapeutic drug design to invasive species removal. "For these gene conversion strategies to work in any context—in the lab or in wild populations—you need the mechanism of gene conversion to work in both males and females," said Cooper, associate professor in the Section of Cell and Developmental Biology, Division of Biological Sciences. "It seems as though the reason this process was previously working in females is because we were closer to the female meiotic window. Now that we've moved Cas9 expression to within the meiotic window in males, it works in them too."
The prince, the mayor, and the U.S. fish that ate Japan
20103C. Elliot, National Geographic, 2022-01-11 16:44:32.
When Crown Prince Akihito visited Chicago on October 3, 1960, his sole request was to visit Shedd Aquarium. Then Mayor Richard J. Daley, an avid angler, presented the prince with a gift that he scooped with a net from one of the tanks himself: 18 bluegills, the official Illinois state fish. The 26-year-old future emperor was already a passionate ichthyologist, and he planned to stock the exotic fish in the moat surrounding his palace, according to accounts in the Chicago Tribune at the time. At windy Chicago O’Hare International Airport the next day with Princess Michiko, Akihito bid the city farewell, carrying a gift that he couldn’t have imagined would cause a decades-long ecological crisis in his homeland. In the intervening six decades, the bluegills became an invasive, species-destroying nightmare, crowding Japanese freshwater lakes and rivers and destroying native fish biodiversity, says Kenji Saitoh, a researcher at the country’s Fisheries Resources and Education Agency. Fortunately, science has marched on in 60 years. Now, Japanese geneticists are experimenting with the gene editing wizardry of CRISPR to sterilize the invasive bluegills. If the initiative succeeds, wildlife managers could use the same technique to rid the U.S. of damaging aquatic invasives such as the Asian carp.
Stakeholder engagement to inform the risk assessment and governance of gene drive technology to manage spotted-wing drosophila
20212A. E. Kokotovich, S. K. Barnhill-Dilling, J. E. Elsensohn, R. Li, J. A. Delborne and H. Burrack, Journal of Environmental Management, 307:114480. 2022-01-04 15:32:08.
Emerging biotechnologies, such as gene drive technology, are increasingly being proposed to manage a variety of pests and invasive species. As one method of genetic biocontrol, gene drive technology is currently being developed to manage the invasive agricultural pest spotted-wing drosophila (Drosophila suzukii, SWD). While there have been calls for stakeholder engagement on gene drive technology, there has been a lack of empirical work, especially concerning stakeholder engagement to inform risk assessment. To help address this gap and inform future risk assessments and governance decisions for SWD gene drive technology, we conducted a survey of 184 SWD stakeholders to explore how they define and prioritize potential benefits and potential adverse effects from proposed SWD gene drive technology. We found that stakeholders considered the most important potential benefits of SWD gene drive technology to be: 1) Decrease in the quantity or toxicity of pesticides used, and 2) Decrease in SWD populations. Stakeholders were most concerned about the potential adverse effects of: 1) Decrease in beneficial insects, 2) Increase in non-SWD secondary pest infestations, and 3) Decrease in grower profits. Notably, we found that even stakeholders who expressed support for the use of SWD gene drive technology expressed concerns about potential adverse effects from the technology, emphasizing the need to move past simplistic, dichotomous views of what it means to support or oppose a technology. These findings suggest that instead of focusing on the binary question of whether stakeholders support or oppose SWD gene drive technology, it is more important to identify and assess the factors that are consequential to stakeholder decision making – including, for example, exploring whether and under what conditions key potential adverse effects and potential benefits would result from the use of SWD gene drive technology.
Modeling CRISPR gene drives for suppression of invasive rodents using a supervised machine learning framework
19764S. E. Champer, N. Oakes, R. Sharma, P. García-Díaz, J. Champer and P. W. Messer, PLoS Comput Biol, 17:e1009660. 2021-12-29 13:01:20.
Invasive rodent populations pose a threat to biodiversity across the globe. When confronted with these invaders, native species that evolved independently are often defenseless. CRISPR gene drive systems could provide a solution to this problem by spreading transgenes among invaders that induce population collapse, and could be deployed even where traditional control methods are impractical or prohibitively expensive. Here, we develop a high-fidelity model of an island population of invasive rodents that includes three types of suppression gene drive systems. The individual-based model is spatially explicit, allows for overlapping generations and a fluctuating population size, and includes variables for drive fitness, efficiency, resistance allele formation rate, as well as a variety of ecological parameters. The computational burden of evaluating a model with such a high number of parameters presents a substantial barrier to a comprehensive understanding of its outcome space. We therefore accompany our population model with a meta-model that utilizes supervised machine learning to approximate the outcome space of the underlying model with a high degree of accuracy. This enables us to conduct an exhaustive inquiry of the population model, including variance-based sensitivity analyses using tens of millions of evaluations. Our results suggest that sufficiently capable gene drive systems have the potential to eliminate island populations of rodents under a wide range of demographic assumptions, though only if resistance can be kept to a minimal level. This study highlights the power of supervised machine learning to identify the key parameters and processes that determine the population dynamics of a complex evolutionary system.
How sci-fi weapon could stop grey squirrels killing Britain’s trees
19723rymeradelle, INentertainment, 2021-12-23 12:41:06.
Grey squirrels pose the greatest threat to British foresters at the moment. They eat the bark of trees, leaving them to die. Picture: Grey squirrel perched on a tree It’s bad enough watching Britain’s ash trees wither from the ash dieback fungus now ravaging our countryside. We can only do so much. The squirrel is an exception to this rule. And it’s not just trees which are paying the price. This pest kills songbirds, and also pinches nests. Worse still, our native red squirrel, which once roamed the entire country — without chewing trees to death — is now an endangered species, clinging on in pockets of Scotland and places such as the Isle of Wight. The number of people living in the area is estimated to be around 200,000. Red Squirrel Survival Trust will make an announcement next month, with Red Squirrel Day on January 21. Its patron, the Prince of Wales, loves the vanishing red so much that he has a squirrel-feeding table in the hallway at Birkhall, his home on the Balmoral estate (where he has also erected ‘Squirrel Crossing’ road signs).
New developments in the field of genomic technologies and their relevance to conservation management
19273G. Segelbacher, M. Bosse, P. Burger, P. Galbusera, J. A. Godoy, P. Helsen, C. Hvilsom, L. Iacolina, A. Kahric, C. Manfrin, M. Nonic, D. Thizy, I. Tsvetkov, N. Veličković, C. Vilà, S. M. Wisely and E. Buzan, Conservation Genetics, 2021-11-11 16:22:03.
Recent technological advances in the field of genomics offer conservation managers and practitioners new tools to explore for conservation applications. Many of these tools are well developed and used by other life science fields, while others are still in development. Considering these technological possibilities, choosing the right tool(s) from the toolbox is crucial and can pose a challenging task. With this in mind, we strive to inspire, inform and illuminate managers and practitioners on how conservation efforts can benefit from the current genomic and biotechnological revolution. With inspirational case studies we show how new technologies can help resolve some of the main conservation challenges, while also informing how implementable the different technologies are. We here focus specifically on small population management, highlight the potential for genetic rescue, and discuss the opportunities in the field of gene editing to help with adaptation to changing environments. In addition, we delineate potential applications of gene drives for controlling invasive species. We illuminate that the genomic toolbox offers added benefit to conservation efforts, but also comes with limitations for the use of these novel emerging techniques.
Genetic control of invasive sea lamprey in the Great Lakes
19270D. Ferreira-Martins, J. Champer, D. W. McCauley, Z. Zhang and M. F. Docker, Journal of Great Lakes Research, 2021-11-08 16:16:20.
The invasive sea lamprey was a significant factor in the collapse of fish stocks in the Great Lakes, and it continues to threaten the multi-billion-dollar fishing industry. Thus, substantial resources are invested annually on sea lamprey control. Current control strategies have reduced sea lamprey populations by up to 90%, but they are expensive and have some limitations, e.g., lamprey-specific biocides applied to larval habitat impact native lampreys, and physical barriers that block adult lamprey access to spawning habitat impede migration of other fishes. Therefore, genetic control options which offer a theoretically powerful and effective pest control tool are being explored, although they have uncertain sociopolitical support, especially given the need to protect sea lamprey in their native range in Atlantic drainages. Here, we present an overview of genetic approaches with potential for application to sea lamprey control in the Great Lakes. We classify these approaches into two major categories: self-limiting (heritable sex ratio ratchet, Trojan gene, split gene drive) and self-sustaining (gene drive-based sex ratio distortion, homing suppression gene drive, toxin-antidote gene drives, and modification-type gene drives to aid suppression). We describe the technical aspects, challenges, and potential application of each method, focusing on gene drives, a fast-evolving research area that was only a distant option for sea lamprey control in previous reviews. We conclude that, given the risk of undesired spread of deleterious alleles from the Great Lakes, self-limiting genetic control options and confined gene drives will likely be preferred over unconfined gene drive options for sea lamprey control.
New Zealand wants to get rid of stoats with genetic engineering
19157C. Weerasinghe, Cyber Layman, 2021-11-05 14:23:23.
The principle of the “gene drive” is to modify a specific gene in a group of specimens of a species and then let the gene spread throughout the population by inheritance, through reproduction. If, as in this case, the aim is to reduce the population of animals, for example, we can make sure that only males are born. New Zealand stoats are not the only animals on which the technique of “gene drive” is thought to be used: for example, there are similar plans for mosquitoes that transmit malaria. The first time the technique proved effective was in 2015, when it was tested on a population of fruit flies; then it was tested on some species of yeast, insects and mice (for which, however, the effectiveness of the technique has not yet been demonstrated), never on an animal as large as an ermine. New Zealand may be the first country to experience such a thing domestically.
A Golden Menace
19202S. Moutinho, Science, 2021-10-21 14:46:14.
An even bigger catastrophe looms: the invasion of the Amazon and its tributaries, part of the largest drainage basin in South America, which spans eight countries and is one of the richest hot spots for biodiversity on the planet. Golden mussels have been documented in the Pantanal wetlands just 150 kilometers from the Téles Pires River, which flows into the Amazon basin and connects to the Tapajós River, a tributary of the Amazon.“It only takes one boat encrusted with the mussel to cross the wetlands for the invader to make a new home in an Amazon river,” says biologist Marcia Divina at the state-owned Brazilian Agricultural Research Corporation. If the invader spreads in the Amazon, it could wipe out native species that scientists have not even studied yet, she adds. “We can’t even calculate the size of the impact.”Despite a late and anemic government response, researchers funded largely by affected hydroelectric companies have developed new tools to track the mussels’ relentless advance. And some are looking to an aggressive form of genetic engineering to eradicate it. That untested strategy is still likely years from being ready to deploy, but scientists see few other ways to slow an invader so easily spread by human transit and trade.
GeneConvene Global Collaborative Webinar Series | Decision and Analysis Tools for Complex Problems
18961Hector Quemada and David O'Brochta, GeneConvene Global Collaborative, 2021-10-13 20:07:26.
The challenges associated with the multiple phases of testing and possible deployment of gene drive-containing organisms appear to have similarities to those associated with various aspects of invasive species management. Preventing unwanted spread of the target species as well as monitoring and surveillance over large spatial scales are just two. Managing invasive species depends on making decisions based on an incomplete and sometimes very limited understanding of the relevant community ecology and the ever-present risk of unintended consequences. Can the deep experiences of those involved in invasive species management be leveraged against challenges in the gene drive domain? This webinar series will begin to explore that question.
Genetically-modified possums and all-in-one trapping machines: funding for new predator-free studies
18787A. Allott, stuff, 2021-09-24 13:32:23.
Research into possum genes and creating an all-in-one predator detecting, luring, and trapping machine are among a handful of projects to receive new funding to help bring them into reality. Predator Free 2050 has awarded $2.4 million in Jobs for Nature funding to six postgraduate and post-doctoral researchers from Otago, Canterbury, Lincoln and Auckland universities. University of Otago researcher Alana Alexander, who is trying to discover which genes are important for possums’ reproduction and survival, is one of them. “Gene drives seem very exciting, but they’re a genie in a bottle. We don’t really want possums in New Zealand, but they are part of the ecosystem in Australia, so making sure it’s contained would be really important.” Alexander said she wants people to understand the risks and benefits, so they can give informed consent when thinking about pest control down the line.
Faut-il miser sur le forçage génétique contre les espèces invasives?
18933P. Minet, Le Temps, 2021-09-12 19:51:46.
Un «gene drive» peut servir à annihiler complètement et rapidement une population d’animaux indésirables. Prometteuse pour lutter contre les espèces invasives, cette technologie a fait l’objet d’âpres débats dans le cadre du congrès mondial de la nature à Marseille. Cela peut paraître paradoxal: dans certaines situations, la protection de la biodiversité passe par l’anéantissement d’une espèce. C’est le cas lorsque des écosystèmes fragiles sont confrontés à l’irruption d’un animal ou d’une plante originaire d’une autre zone géographique, et qui a le potentiel de détruire ou de supplanter les espèces locales. L’exemple typique est celui de nombreuses îles où des rats introduits par l’être humain déciment les oiseaux en mangeant leurs œufs.
To exterminate, or not to: Scientists debate tweaking wild genomes
18529French Press Agency, Daily Sabah, 2021-09-12 16:11:31.
veryone remembers Jeff Goldblum's famous speech in 1993 classic Jurassic Park: “Your scientists were so preoccupied with whether they could, they didn't stop to think if they should.” Well, these scientists are debating whether one should. In the movie, reconstructing and tweaking genetic material had made it possible to bring dinosaurs back to life. Today, a technology that manipulates animal genomes, called gene drive, has become a reality. The goal, however, is not to revive long-gone species, but to eliminate invasive ones. Steven Spielberg's film was set on an imaginary island off the coast of Costa Rica, and it is also on an island that the first open-air experiments in programmed extinction could take place, according to experts gathered at the International Union for the Conservation of Nature (IUCN) Congress in Marseille. It could happen within a decade, they told Agence France-Presse (AFP). That's because fragile island ecosystems are in crisis. Dozens of vertebrate species have vanished in the last century, and dozens more are on a glide path to extinction. The culprits are non-native rats, snakes and mosquitoes – all introduced by humans, for the most part by accident – that eat bird eggs, infect birds with disease, or outcompete indigenous amphibians and mammals. For more than 20 years, Island Conservation has been working to eradicate rodents and other invasive alien species, which are a major threat to biodiversity globally, the organization's Royden Saah told AFP. The conservation NGO has been successful on two Galapagos islands – Seymour North and Mosquera – using traps and poison-delivering drones. But species eradication using these tools is costly and has no guarantee of success. Rat poison is effective, but poses risks to other species.
Scientists debate promise, peril of tweaking wild genomes
18517J. Zamora, Phys Org, 2021-09-11 14:53:57.
In the movie Jurassic Park, reconstructing and tweaking genetic material makes it possible to bring dinosaurs back to life. Today, a technology that manipulates animal genomes, called gene drive, has become a reality. The goal, however, is not to revive long-gone species, but to eliminate invasive ones. Steven Spielberg's film was set on an imaginary island off the coast of Costa Rica, and it is also on an island that the first open-air experiments in programmed extinction could take place, according to experts gathered at the International Union for the Conservation of Nature (IUCN) Congress in Marseille. It could happen within a decade, they told AFP. That's because fragile island ecosystems are in crisis. Dozens of vertebrate species have vanished in the last century, and dozens more are on a glide path to extinction. The culprits are non-native rats, snakes and mosquitoes—all introduced by humans, for the most part by accident—that eat bird eggs, infect birds with disease, or outcompete indigenous amphibians and mammals.
$1M in funding for project to cull mouse plagues
18349K. Brown, University of Adelaide NEWSROOM, 2021-08-31 13:47:59.
South Australian researchers are set to use genetic tools to help find innovative solutions to the devastating mouse plagues that have caused massive economic damage to Australian farmers.The University of Adelaide has been awarded $1 million in funding from the South Australian Government’s Research and Innovation Fund (RIF), to undertake the ground-breaking Genetic Biocontrol Technology for Invasive Pests, or Gene Drive, project, in conjunction with the Department for Environment and Water.Researchers from the University of Adelaide will develop genetic strategies to suppress invasive rodents with maximum specificity and safety. The team will also conduct research to engage with stakeholders to understand community views and concerns.
Knowing and Controlling: Engineering Ideals and Gene Drive for Invasive Species Control in Aotearoa New Zealand
18025C. H. Ross, Nature Remade: Engineering Life, Envisioning Worlds, 2021-08-10 17:51:46.
On the islands of Aotearoa, also called New Zealand, invasive species have been a prominent and persistent concern for local ecosystems. Traditional methods of biological control, though, can be difficult to implement and often have harmful side- effects for the environment and human health. Recent developments in genetic engineering have led to the creation of a new technology called gene drive, which some have suggested may pro-vide a safer, easier alternative way to “restore damaged ecosystems and save endangered wildlife by genetically removing invasive species.” 1 While the promises of gene drive for invasive species control have attracted the attention of many in Aotearoa New Zealand interested in preserving or restoring the islands’ native environment, at the same time it has prompted calls for caution regarding their controllability and possible unintended consequences of their use. 2 However, the consideration of gene drive for the control of invasive species in Aotearoa New Zealand is more than just an issue of a controversial use of emerging biotechnology. At stake also are critical questions about what it means to know and control life. What are the kinds of knowledge that enable and underwrite the notions of controlling of life? If gene drive confers the power to control inva-sive species, who decides whether and how that control is exercised and with what responsibilities? And, crucially, what visions of the world are embedded in the aspirations of scientifically knowing and technologically controlling life?Controlling life has long been a central aspiration of the biological sciences. In the early twentieth century, aspirations to greater control over life manifested in rigorous laboratory experimentation, attempts to engineer organisms to be more amenable to human purposes, and explanatory commitments to a mechanistic conception of life. 3 Mechanistic approaches have been ubiquitous in biological practice aimed at bringing living things and their functions into the purview of human intention and volition by isolating, manipulating, and better understanding the function of more fundamental parts. 4 The widespread mechanistic approaches in biology
GeneConvene Global Collaborative Webinar Series | Invasive Species Management: Informing Gene Drive Considerations
19307David O'Brochta and Hector Quemada, GeneConvene Global Collaborative, 2021-08-07 13:38:24.
The management, control and elimination of invasive species involves solving problems that have analogs to those anticipating the use of gene drive technologies to control and eliminate malaria in Africa. Avoiding unintended consequences from interventions designed to reduce or remove a species from an ecosystem has parallels in some applications of gene drive technologies. Monitoring and surveilling for the movement of invasive species is critical for making management decisions and methods and approaches that have been devised to deal with challenges such as large geographic areas, low species densities, limited resources to name just a few could inform thinking about monitoring and surveillance of gene drive-containing organisms. This series of webinars by invasive species specialists will feature research into how these challenges are being successfully addressed.
The Promise of Genetics and Genomics for Improving Invasive Mammal Management on Islands
17936B. T. Burgess, R. L. Irvine, G. R. Howald and M. A. Russello, Frontiers in Ecology and Evolution, 9. 2021-08-03 13:21:15.
Invasive species are major contributors to global biodiversity decline. Invasive mammalian species (IMS), in particular, have profound negative effects in island systems that contain disproportionally high levels of species richness and endemism. The eradication and control of IMS have become important conservation tools for managing species invasions on islands, yet these management operations are often subject to failure due to knowledge gaps surrounding species- and system-specific characteristics, including invasion pathways and contemporary migration patterns. Here, we synthesize the literature on ways in which genetic and genomic tools have effectively informed IMS management on islands, specifically associated with the development and modification of biosecurity protocols, and the design and implementation of eradication and control programs. In spite of their demonstrated utility, we then explore the challenges that are preventing genetics and genomics from being implemented more frequently in IMS management operations from both academic and non-academic perspectives, and suggest possible solutions for breaking down these barriers. Finally, we discuss the potential application of genome editing to the future management of invasive species on islands, including the current state of the field and why islands may be effective targets for this emerging technology.
Invasive Mice and Engineered Genes
17952W. M. Adams and K. H. Redford, Yale University Press Blog, 2021-08-02 12:36:13.
On Gough Island, a steep speck of land deep in the South Atlantic, giant mice eat albatross chicks as they sit on their nests. They are house mice, accidental arrivals on the ships of long-dead sealers. But they have lost their secretive, timid, mousy ways. Over numerous generations, on an island without predators, they have become predators themselves. They have grown bigger, and fierce. The internet offers gruesome videos of Tristan albatross chicks being eaten alive in the night. The house mice of Gough Island are examples of one of the most serious and intractable drivers of biodiversity decline, invasive species. Not all species introduced by people outside their normal range become invasive, but invasive species are the most common threat to amphibians, reptiles, and mammals on the IUCN Red List, and have been a contributing cause in a quarter of plant extinctions and a third of animal extinctions in recent centuries. Traditional tools for addressing invasive species include traps, guns, fences, and particularly poisons. Though often effective, these often have undesired, and sometimes unexpected, knock-on effects on native species. Synthetic biology, the application of new genetic tools like CRISPR, is being explored as a source of new approaches to control with fewer side effects. The use of such methods in conservation blurs the distinction between what is natural and what is human-made.
World Nature Conservation Day: Technology to Forge a Path for Nature Conservation and Communities
17912P. Becker, Isand Conservation, 2021-07-28 15:23:24.
Gene drives are a genetic phenomenon that occurs in nature and causes a gene or trait to have a greater than 50% chance of inheritance. Island Conservation and partners have formed the Genetic Biocontrol of Invasive Rodents (GBIRd) partnership, to explore the technical and social feasibility of creating a gene drive to eliminate invasive rodents on islands. For example, a gene drive that causes rats to produce all male offspring spreads through an invasive population until there is no natural recruitment. On this World Nature Conservation Day, I would like to invite you to reflect on the scale, speed and costs of the efforts needed to address current conservation challenges. Gene drive could be a game-changer for conservation, making nature restoration and sustainable development gains possible on islands where these are currently out of reach today. Combined with existing tools, gene drive could transform the future of island restoration, drastically increasing the scope, scale, and pace of our work, and realizing benefits for island wildlife and communities around the world.
Mice Plague Eastern Australia in Record Numbers
17751B. Nogrady, The Scientist, 2021-07-12 13:50:17.
Just before Christmas last year, Julie Leven and her husband Des took their camper up to visit their son in northern New South Wales, Australia. Driving back at night to their home in Gilgandra, around 430 kilometers northwest of Sydney, they saw masses of white spots moving across the dark road surface. The spots, they soon realized, were mice. Once they reached their house, the Levens saw a scene of rodent devastation. Mice had invaded their home in such numbers that it was unlivable. The creatures had gnawed their way into the pantry and ruined all the food they could get into. Their droppings and pungent urine were spread from one end of the dwelling to the other, across soft furnishings and bedding. The rodents had even eaten the insulation around the engine wiring in two tractors and ruined their harvested hay bales.
Victory: NSW Government Invests in Humane Mice Control!
17224PETA Australia, PETA Australia, 2021-06-05 16:21:19.
Just two weeks after calling us “brainless” for suggesting that the state government invest in more ethical, eco-friendly methods of mice control – Minister for Agriculture Adam Marshall announced a $1.8 million package to “fast-track the delivery of next generation ‘gene drive’ technology to control future plagues”. The money will fund a three-year programme of genetic biocontrol research, led by the University of Adelaide, CSIRO, and the Centre for Invasive Species Solutions, to identify fast-acting gene drives designed to spread an inherited characteristic through a population. The research will test two strategies for population control, including an approach which eliminates sperm carrying the X chromosome, producing more male than female offspring, and a second approach of making female mice infertile. PETA has been talking about immunocontraception methods of controlling invasive animal populations for years, so we’re pleased to see the government is finally using science to tackle this problem in a more ethical and eco-friendly manner. Had it acted sooner, millions of small animals, including non-target species, would have been spared slow and agonising deaths. Last month, the New South Wales government announced it would use a new, strong poison and spruiked it as “napalm” for mice. Leading rodent experts questioned the plan, warning that the poison’s use came with a high risk of killing native and domestic animals as well. Dr Peter Brown, leader of the rodent management research team at CSIRO, told The Guardian, “The anti-coagulants can accumulate up through the food chain, and so birds of prey or other animals can be feeding on dead mice and they could potentially get a lethal dose themselves through secondary poisoning.”
New biocontrol research to help prevent mice plagues
17206Anonymous, The National Tribune, 2021-06-04 15:41:51.
Scientists at the University of Adelaide are partnering with the CSIRO and the Centre for Invasive Species Solutions on breakthrough genetic biocontrol research to help control mice populations and prevent future mice plagues. The three-year research program will identify fast acting gene drives, which are designed to spread an inherited characteristic for population control through mice populations at higher-than-normal rates. This would effectively enable scientists to interrupt the breeding cycle and keep mice populations at manageable levels. The NSW Government will provide $1.8 million towards the project to fast-track the delivery of the ‘gene drive technology’ as part of a range of measures not only to mitigate the impacts of the mice currently across NSW, but also to create options to reduce the impact of future population spikes.
Gene drive could be a game changer for future mouse control.
17214Anonymous, Centre for Invasive Species Solutions, 2021-06-03 16:02:28.
We are proud to announce we will be coordinating a brand new, three-year program of genetic biocontrol research, which will identify fast acting gene drives designed to spread an inherited characteristic through a population at higher-than-normal rates. Using targeted gene drives, scientists aim to interrupt the breeding cycle of mice and potentially other ferals, which could keep populations at manageable levels. The $1.8 million research program will be led by Professor Paul Thomas at our partner organisation the University of Adelaide in collaboration with our member organisation CSIRO. The NSW Minister for Agriculture, Adam Marshall said cutting edge solutions meant future mouse plagues could be extinguished before they begin. This specific research funding will test two strategies for population control and recommend at least one for future suppression of mice. The ‘X-shredder’ approach eliminates sperm carrying the X chromosome, producing more male than female offspring. The ‘female infertility’ approach spreads a genetic modification that would eventually make females infertile. We look forward to seeing the outcomes of this world-class innovative research being led by Aussie scientists.
Scientists want to alter rodent genes to prevent mice plagues
17092P. Hannon, The Sydney Morning Herald, 2021-05-23 10:52:32.
Mice plagues, such as the one ravaging parts of inland NSW, could become a thing of the past if scientists succeed in modifying the genes of the rodents so that populations crash before they can take off. Paul Thomas, a researcher at the University of Adelaide, is part of an international consortium including the CSIRO and the US Department of Agriculture, studying how to safely alter genes to make female mice infertile. The techniques learned could potentially be applied to other damaging invasive mammals such as cats and foxes.
Gene-Editing Approach To Control the Invasive Gray Squirrel
16572M. Campbell, Technology Networks, 2021-03-08 14:33:09.
Biodiversity refers to the extent of the variety of life that is found on planet Earth – and it is currently under threat. Changes in biodiversity have been flagged as "surpassing safe limits" for several years, and world leaders and scientists across the globe are consequently exploring different ways to address the crisis. Invasive species, defined by National Geographic as "an organism that is not indigenous, or native, to a particular area", threaten planet Earth's biodiversity to an even greater extent than climate change. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Global Assessment Report found that the number of invasive species per country have risen by ~70% since 1970 across 21 countries that were included in the report. An example of an invasive species is the gray squirrel Sciurus carolinensis found in the UK, which outcompetes the native red squirrel for resources and habitats and carries diseases that are not pathogenic to themselves but can kill red squirrels.
Ecology: Gene drives may help control invasive grey squirrel in the UK
16557A. Korn, EurekaAlert, 2021-03-04 19:50:50.
Gene drives introduce genes into a population that have been changed to induce infertility in females, allowing for the control of population size. However, they face technical challenges, such as controlling the spread of altered genes as gene drive individuals mate with wild individuals, and the development of genetic resistance, which may render the gene drive ineffective. To address these challenges, Nicky Faber and colleagues used computer modelling to investigate the effectiveness of a combination of three gene drive technologies using the grey squirrel as a case study.
Genetically modified squirrels could curb growing population of greys
16542S. Knapton, Telegraph, 2021-03-04 16:06:59.
Mutant grey squirrels, genetically modified to spread infertility genes, could be released into the wild to tackle the burgeoning population,
Expert reaction to a paper suggesting that gene drives could be used to help control grey squirrel numbers in the UK
16540Anonymous, Science Media Centre, 2021-03-04 15:59:10.
This study assesses the prospects for using a gene drive to control invasive grey squirrels in the UK. This is a modelling study exploring the potential for such an approach – no such gene drives currently exist and developing them for grey squirrels would be quite a long-term project. Invasive species are a major problem for biodiversity and conservation; in many cases there are no adequate methods for control. Genetic methods may provide new options, potentially both more effective and with fewer off-target effects. Most work on gene drives has focused on mosquitoes; this study is unusual in focusing on a vertebrate (grey squirrel), though there has also been interest in targeting invasive populations of mice and rats on islands.
CRISPR gene drives may come to a squirrel near you.
16536Anonymous, NewsBeezer, 2021-03-04 15:48:43.
Today’s gene drive technologies could be blended to provide control of the invasive gray squirrel population in the UK – with minimal risk to other populations, according to a new modeling published in the journal Scientific reports. Gene driving introduces altered genes into a population that can cause infertility in women. This allows scientists to control the size of the population. However, this tactic faces technical difficulties such as controlling the spread of altered genes while certain animals that are part of the gene drive population mate with uncontrolled populations ̵
Demographic and psychographic drivers of public acceptance of novel invasive pest control technologies
17086F. Eppink, P. J. Walsh and E. MacDonald, Ecology and Society, 26. 2021-03-01 15:15:26.
Invasive mammals are a primary threat to New Zealand's endemic species. In remote areas, aerial delivery of poison is the preferred method of pest management, although it faces some public backlash. Novel pest control technologies are currently being investigated as alternatives but may face similar concerns. To investigate potential social and demographic determinants of public perceptions of new methods for pest control, we conducted a national choice experiment, focused on several novel technologies: gene drives, Trojan females, and species-specific poisons. We found that preferences strongly depend on the type of technology, with Trojan female technology strictly preferred to the other two. Although several characteristics affected preferences in predictable ways education, trust in science, and liberal political leaning increased acceptance ;the same did not hold with preferences for aerial delivery. Our results are useful for targeting future engagement campaigns and leveraging existing efforts.
Designing gene drives to limit spillover to non-target populations
16516G. Greenbaum, M. W. Feldman, N. A. Rosenberg and J. Kim, PLOS Genetics, 17:e1009278. 2021-02-25 15:02:27.
We develop mathematical models of gene-drive dynamics that incorporate migration between a target and non-target populations to investigate the possibility of effectively applying a gene drive in the target population while limiting its spillovers to the non-target population (‘differential targeting’). We observe that the feasibility of differential targeting depends on the gene-drive design specification, as well as on the migration rates between the populations. Even when differential targeting is possible, as migration increases, the possibility for differential targeting disappears. We find that differential targeting can be effective for low migration rates, and that it is sensitive to the design of the gene drive under high migration rates. We suggest that differential targeting could be used, in combination with other mitigation measures, as an additional safeguard to limit gene drive spillovers.
Scientifically framed gene drive communication perceived as credible but riskier
16406E. A. MacDonald, E. D. Edwards, J. Balanovic and F. Medvecky, People and Nature, 2021-02-17 18:23:29.
Framing is a communication technique in which certain beliefs or values are emphasized that resonate with the target audience. Framing may increase how much people objectively think about new information and update their opinions; framing may mitigate emo
A Code of Ethics for Gene Drive Research
16379G. J. Annas, C. L. Beisel, K. Clement, A. Crisanti, S. Francis, M. Galardini, R. Galizi, J. Grünewald, G. Immobile, A. S. Khalil, R. Müller, V. Pattanayak, K. Petri, L. Paul, L. Pinello, A. Simoni, C. Taxiarchi and J. K. Joung, The CRISPR Journal, 4:19:1-8. 2021-02-10 14:57:13.
A code of ethics can be a useful tool for all parties involved in the development and regulation of gene drives and can be used to help ensure that a balanced analysis of risks, benefits, and values is taken into consideration for the interest of society and humanity. We have developed a code of ethics for gene drive research with the hope that this code will encourage the development of an international framework that includes ethical guidance of gene drive research and is incorporated into scientific practice by gaining broad agreement and adherence.
Assisting Evolution: How Far Should We Go to Help Species Adapt?
16369E. Kolbert, YaleEnvironment360, 2021-02-09 20:28:55.
It was a hot, intensely blue day in the Australian Outback, about 350 miles north of Adelaide. I was tagging along with Moseby as she checked the batteries on the motion-sensitive cameras that dot Arid Recovery, an ecosystem restoration project she and her husband launched in 1997. The project sprawls over 47 square miles of red earth and scrub. It’s entirely surrounded by a six-foot-tall fence, which is designed to keep out feral cats and foxes. Inside the main fence is a series of smaller fenced-in paddocks. Several years ago, Moseby decided to start adding cats into some of these. Her reasoning was simple and, in its own way, radical. The outback ecosystem had been so fundamentally changed, that, if the native animals were to survive, they would have to change, too. Perhaps they could be trained to avoid cats, which were introduced to the country by the British colonists and now can be found virtually everywhere in Australia, including most islands.
Should we dim the sun? Will we even have a choice
16384E. Klein, New York Times, 2021-02-09 15:06:18.
“Under a White Sky” is going to be on my best books of 2021 list. It’s a wonderful work. Kolbert is the Pulitzer Prize-winning author of “The Sixth Extinction,” which you may have read. She is a staff writer at The New Yorker and just one of the great science journalists of this time, and particularly one of the great climate journalists of this age. But this book, this book’s existence is evidence of how badly that fight is going. This is a book about what we are going to need to contemplate in the coming years that we don’t want to. It’s a book about taking responsibility for how irreversibly we have altered the natural world; how often we have tried to control it, and then watched those attempts at control fail; how often the best most scientific minds of the age have come up with some brilliant solution, implemented it, and then watched calamity result. And at the same time — and this is what makes the book so worthwhile — it is a book about how there is no going back. Not now, not ever. We are in the Anthropocene. The future from here is an endless layering on of new efforts to control the consequences of our past efforts. We don’t get to flinch or pretend we don’t have to contemplate any of this. We’ve gone too far. One of the hardest things to do as a writer — and I tell you this from personal experience — is to write ambivalence. It’s easy to write a polemic or a sharp take. It is hard to write down the middle path, where you are simply describing things as they are, knowing that every possible obvious answer you can come to is probably a bad one, knowing that the hubris embedded in past attempts to solve this problem means any future brilliant idea is likely to end that way, too, but that doesn’t mean we can do nothing. But Kolbert walks that path really beautifully here, which is why I wanted to talk to her for the show. As always, my email is [email protected]. I’m always interested to know who you’d like to see on the show. The weirder, the better. So send me your guest suggestions. Here’s Elizabeth Kolbert.
Grey squirrels: is birth control the solution to Britain’s invasive species problem?
16275J. Gilchrist, The Conversation, 2021-02-03 17:03:29.
As with the UK’s other invasive species, such as rabbits, signal crayfish and Japanese knotweed, introducing the grey squirrel has proved to be an expensive mistake. Not only do grey squirrels displace red squirrels, they strip bark from trees. A recent report estimated that this could cost commercial forestry and native woodlands £1.1 billion (US$1.5 billion) over the next 40 years, including revenue lost to damaged timber, reduced carbon storage, tree replacement costs and squirrel control. Despite efforts to kill grey squirrels over several decades, their populations remain large and widespread.
The Promises and Realities of Integration in Synthetic Biology: A View From Social Science
16287L. Carter and A. Mankad, Frontiers in Bioengineering and Biotechnology, 8. 2021-01-21 17:25:32.
We take stock of thepromises and realities of science integration by sharing our experiences of embarking onthis very challenge in Australia. We conclude by offering suggestions for bringing aboutthe enabling conditions for improved integration across the natural and social sciences.Four key actions are articulated to help pivot synthetic biology toward a more integratedscientific endeavor: (a) formalizing inclusivity from inception to project conclusion; (b)valuing differing philosophical positions as a strength rather than a barrier; (c) acceptingthat integration takes persistence and communication but is immensely rewarding; and(d) promoting meaningful interactions, such as pursuing joint opportunities, co-designingand co-publishing research. We argue that these actions arekey enablers for realizingscience integration in synthetic biology.
CRISPR and the splice to survive: New gene-editing technology could be used to save species from extinction—or to eliminate them.
16011E. Kolbert, New Yorker, 2021-01-11 14:25:59.
About a year ago, not long before the pandemic began, I paid a visit to the center, which is an hour southwest of Melbourne. The draw was an experiment on a species of giant toad known familiarly as the cane toad. The toad was introduced to Australia as an agent of pest control, but it promptly got out of control itself, producing an ecological disaster. Researchers at the A.C.D.P. were hoping to put the toad back in the bottle, as it were, using crispr.
The New Yorker Magazine: Gene Drives as a Tool for Saving Nature
16277E. Heber, Island Conservation, 2021-01-03 17:07:04.
In a recent New Yorker Magazine article, entitled “CRISPR and the Splice to Survive,” journalist and best-selling author Elizabeth Kolbert dives into the world of gene drive research. She touches on aspects of gene drive research from altering the toxin produced by cane toads to recovering nearly-extinct trees to eradicating invasive mice through attrition, all to understand the possibilities this tool could hold.
Invasive Species Control and Resolution of Wildlife Damage Conflicts: A Framework for Chemical and Genetically Based Management Methods
15286L. Clark, J. Eisemann, J. Godwin, K. E. Horak, K. Oh, J. O’Hare, A. Piaggio, K. Pepin and E. Ruell, GMOs: Implications for Biodiversity Conservation and Ecological Processes, 2020-12-02 16:52:40.
Vertebrate wildlife damage management relates to developing and employing methods to mitigate against damage caused by wildlife in the areas of food production, property damage, and animal or human health and safety. Of the many management tools available
Gene drives, species, and compassion for individuals in conservation biology
15072Y. Rohwer, Ethics, Policy and Environment, 2020-11-10 18:20:29.
In this paper I argue that these compassionate conservationists have a moral obligation to support the investigation and development of genetic modification technologies because of their potential to minimize suffering and eliminate killing in conservation. Furthermore, I will end the paper by suggesting that these genetic technologies can help avoid actions that could be damaging to one's moral character.
When Extinction is Warranted: Invasive Species, Suppression-Drives, and the Worst-Case Scenario
15050A. C. Thresher, Ethics, Policy and Environment, 2020-11-09 19:31:52.
The focus of this paper is on one such risk ? the danger of a suppression-drive escaping containment and wiping out the target species globally. Here, I argue that in most cases this risk is significant enough to warrant holding off on the technology. In some cases, however, we can bypass the precautionary principle by using a dominance approach that hinges on what I term the ?Worst-Case Clause?. This clause, in turn, provides us with a litmus test that can be fruitfully used to determine what species are viable targets for suppression-drives in the wild. Using this metric in concert with other considerations, I suggest that only three species are currently possible viable targets ? the European rabbit, ship rat, and Caribbean Tree Frog.
Progress Toward Zygotic and Germline Gene Drives in Mice
14852C. Pfitzner, M. A. White, S. G. Piltz, M. Scherer, F. Adikusuma, J. N. Hughes and P. Q. Thomas, The CRISPR Journal, 3:388-397. 2020-10-20 17:17:24.
Here, we investigated the efficiency of CRISPR-Cas9-based gene drives in Mus musculus by constructing "split drive" systems where gRNA expression occurs on a separate chromosome to Cas9, which is under the control of either a zygotic (CAG) or germline (Vasa) promoter.
Microbiome Innovation in Agriculture: Development of Microbial Based Tools for Insect Pest Management
19716M. Qadri, S. Short, K. Gast, J. Hernandez and A. C.-N. Wong, Frontiers in Sustainable Food Systems, 4. 2020-10-06 12:11:19.
This review emphasizes the potential and use of microbes in sustainable insect pest management. We first review the diverse insect traits shaped by insect-microbe associations that span nutrition, immunity, ecological interactions with natural enemy, insecticide resistance, and behavior. This is followed by discussing different microbiome manipulation approaches to alter pest traits, describing some of the opportunities and obstacles for each approach. We then highlight microbiomes as untapped chemical inventories to discover novel biopesticides, including plant-incorporated protectants and semiochemicals. The last topic covered is the use of beneficial microbes to improve mass-reared insects' performance for autocidal programs, including sterile insect technique and incompatible insect technique, in which we identify topics where data are limited or inconclusive, for future research.
Why the UK could end up deploying risky gene drives while ignoring natural biological control
14385J. Mathews, GM Watch, 2020-09-14 15:10:57.
First they cloned Dolly the sheep. Now they’re targeting grey squirrels
Novel combination of CRISPR-based gene drives eliminates resistance and localises spread
14172N. R. Faber, G. R. McFarlane, R. C. Gaynor, I. Pocrnic, C. B. A. Whitelaw and G. Gorjanc, bioRxiv, 2020-08-27 14:22:46.
We present HD-ClvR, a novel combination of CRISPR-based gene drives that eliminates resistance and localises spread. As a case study, we model HD-ClvR in the grey squirrel (Sciurus carolinensis), which is an invasive pest in the UK and responsible for both biodiversity and economic losses.
Maintenance management and eradication of established aquatic invaders
13936D. Simberloff, Hydrobiologia, 22. 2020-08-06 13:34:15.
The rapid development of technologies based on genetics has engendered excitement about possibly eradicating or controlling terrestrial invaders, and such technologies may also prove useful for certain aquatic invaders. Methods of particular interest, alone or in various combinations, are gene-silencing, RNA-guided gene drives, and the use of transgenes.
Development of zygotic and germline gene drives in mice
12531C. Pfitzner, J. N. Hughes, M. A. White, M. Scherer, S. G. Piltz and P. Q. Thomas, bioRxiv, 2020-06-21 15:15:40.
Here we investigated the efficiency of CRISPR/Cas9-based gene drives in Mus musculus by constructing "split drive" systems with Cas9 under the control of zygotic (CAG) or germline (Vasa) promoters.
Genetic Biocontrol for Invasive Species
11964J. L. Teem, L. Alphey, S. Descamps, M. P. Edgington, O. Edwards, N. Gemmell, T. Harvey-Samuel, R. L. Melnick, K. P. Oh, A. J. Piaggio, J. R. Saah, D. Schill, P. Thomas, T. Smith and A. Roberts, Frontiers in Bioengineering and Biotechnology, 8:452. 2020-05-25 18:12:26.
Invasive species are increasingly affecting agriculture, food, fisheries, and forestry resources throughout the world. As a result of global trade, invasive species are often introduced into new environments where they become established and cause harm to human health, agriculture, and the environment. Prevention of new introductions is a high priority for addressing the harm caused by invasive species, but unfortunately efforts to prevent new introductions do not address the economic harm that is presently manifested where invasive species have already become established. Genetic biocontrol can be defined as the release of organisms with genetic methods designed to disrupt the reproduction of invasive populations. While these methods offer the potential to control or even eradicate invasive species, there is a need to ensure that genetic biocontrol methods can be deployed in a way that minimizes potential harm to the environment. This review provides an overview of the state of genetic biocontrol, focusing on several approaches that were the subject of presentations at the Genetic Biocontrol for Invasive Species Workshop in Tarragona, Spain, March 31st, 2019, a workshop sponsored by the OECD’s Co-operative Research Program on Biological Resource Management for Sustainable Agricultural Systems. The review considers four different approaches to genetic biocontrol for invasive species; sterile-release, YY Males, Trojan Female Technique, and gene drive. The different approaches will be compared with respect to the efficiency each affords as a genetic biocontrol tool, the practical utility and cost/benefits associated with implementation of the approach, and the regulatory considerations that will need to be addressed for each. The opinions expressed and arguments employed in this publication are the sole responsibility of the authors and do not necessarily reflect those of the OECD or of the governments of its Member countries.
Development of control and sterilization technology for bluegill by genome editing
20100M. A. Madsen, Nippon Suisan Gakkaishi, 86:100-100. 2020-03-31 09:55:36.
This article is in Japanese
What squirrels can teach us about why, when, and how to use gene drives
8184Rebecca Nesbit, synbiobeta, 2020-03-05 20:03:01.
As the last ice age drew to a close, red squirrels made Britain their home. They adapted to a changing landscape and thrived as the UK’s only squirrel species. That all changed in 1876 when grey squirrels were introduced to England from North America as an ornamental species in the grounds of stately homes.
Public Opinion Towards Gene Drive as a Pest Control Approach for Biodiversity Conservation and the Association of Underlying Worldviews
7348E. A. MacDonald, J. Balanovic, E. D. Edwards, W. Abrahamse, B. Frame, A. Greenaway, R. Kannemeyer, N. Kirk, F. Medvecky, T. L. Milfont, J. C. Russell and D. M. Tompkins, Environmental Communication-a Journal of Nature and Culture, 15:1-16. 2020-01-27 21:27:11.
Synthetic gene drive approaches are nascent technologies with potential applicability for pest control for conservation purposes. Responsible science mandates that society be engaged in a dialogue over new technology, particularly where there exist global ramifications as with gene drive. We hypothesize that public attitudes towards gene drive are not formed on scientific knowledge or demographics alone, but are heavily influenced by underlying worldviews, which encapsulate a broad and interactive system of attitudes, beliefs, and values. To test this, we conducted a national survey in New Zealand (n = 8199) and found that respondents clustered into four distinct segments with underlying worldviews, better able to explain attitudes toward gene drive than either the participants' scientific knowledge or other explanatory factors such demographics, political ideology or religiosity. We found that the use of gene drive for biodiversity conservation currently has moderate (32%) levels of support in New Zealand but that varied substantially across the four segments. Should gene drive become a technically viable approach for pest control, understanding the worldviews that shape public decision-making can guide a more empathetic engagement process and empower society to participate in informed decision-making about if and how gene drive should be used for conservation purposes.
Regulation of GM Organisms for Invasive Species Control
6701H. J. Mitchell and D. Bartsch, Frontiers in Bioengineering and Biotechnology, 7:1-11. 2020-01-21 18:17:37.
Invasive species can cause significant harm to the environment, agriculture, and human health, but there are often very limited tools available to control their populations. Gene drives (GD) have been proposed as a new tool which could be used to control or eliminate such species. Here, GD describes a variety of molecular biology applications which all enable the introduction of genetic elements at a higher than expected frequency. These elements can change the genotypes in target populations rapidly with consequences either for (intrinsic) fitness or host-parasite interaction, or both. Beneficial applications are foreseen for human and animal health, agriculture, or nature conservation. This rapidly developing technology is likely to have major impacts in the fight against various diseases, pests, and invasive species. The majority of GD applications involve genetic engineering and novel traits. Therefore, applicants and GMO regulators need to interact to achieve the benefits in innovation while cautiously avoiding unacceptable risks. The release into the environment may include transboundary movement and replacement of target populations, with potential impact on human/animal health and the environment. This article summarizes knowledge-based discussions to identify information gaps and analyzes scenarios for responsible introduction of GD organisms into the environment. It aims to connect the latest scientific developments with regulatory approaches and decision-making.
Optimal control and analysis of a modified trojan Y-Chromosome strategy
11491M. A. Beauregard, R. D. Parshad, S. Boon, H. Conaway, T. Griffin and J. J. Lyu, Ecological Modelling, 416. 2020-01-15 20:19:52.
The Trojan Y Chromosome (TYC) strategy is a promising eradication method that attempts to manipulate the female to male ratio to promote the reduction of the population of an invasive species. The manipulation stems from an introduction of sex-reversed males, called supermales, into an ecosystem. The offspring of the supermales is guaranteed to be male. Mathematical models have shown that the population can be driven to extinction with a continuous supply of supermales. In this paper, a new model of the TYC strategy is introduced and analyzed that includes two important modeling characteristics, that are neglected in all previous models. First, the new model includes intraspecies competition for mates. Second, a strong Allee effect is included. Several conclusions about the strategy via optimal control are established. These results have large scale implications for the biological control of invasive species.
Metaphor, Trust and Support for Non-native Species Control
13833P. A. Kohl, S. J. Collins and M. Eichholz, Environmental Communication, 14:672-685. 2020-01-07 15:29:47.
This experimental study used a representative sample of U.S. residents (N = 1,042) to test whether the use of the term "invasive" increases support for non-native species control efforts. The term invasive had a small influence on support for two out of three non-native species control methods. We also found stronger support for control methods using gene editing technologies than control methods using poison.
Genetic control of Invasive carp
13941MAISRC, Minnesota Aquatic Invasive Species Research Center, 2019-10-16 15:08:53.
This project focuses on a novel method of biocontrol for common carp which will complement existing technologies by introducing a synthetic species-like barrier to reproduction. Researchers will use programmable transcription activators to drive lethal embryonic overexpression of endogenous genes in hybrid embryos.
Biological control of pests and a social model of animal welfare
16284A. Mankad, U. Kennedy and L. Carter, Journal of Environmental Management, 247:313-322. 2019-06-25 17:21:12.
We consider the role of perceived humaneness or, more accurately, animal welfare as it relates to managing invasive species from a scientific and social perspective. In order to highlight and articulate particular nuances and standards across different pest control contexts, we use three case examples (feral cats, wild rabbits, and invasive cane toads) and explore where biological pest control and animal welfare interests intersect.
The association between mitochondrial genetic variation and reduced colony fitness in an invasive wasp
13731J. Dobelmann, A. Alexander, J. W. Baty, N. J. Gemmell, M. A. M. Gruber, O. Quinn, T. Wenseleers and P. J. Lester, Molecular Ecology, 28:3324-3338. 2019-06-24 19:25:29.
Despite the mitochondrion's long-recognized role in energy production, mitochondrial DNA (mtDNA) variation commonly found in natural populations was assumed to be effectively neutral. However, variation in mtDNA has now been increasingly linked to phenotypic variation in life history traits and fitness. We examined whether the relative fitness in native and invasive common wasp (Vespula vulgaris) populations in Belgium and New Zealand (NZ), respectively, can be linked to mtDNA variation.
Exploring Stakeholder Perspectives on the Development of a Gene Drive Mouse for Biodiversity Protection on Islands: Workshop Report
11581M. Farooque, S. K. Barnhill-Dilling, J. Shapiro and J. Delborne, North Carolina State University, 2019-06-01 15:28:38.
The “Exploring Stakeholder Perspectives on the Development of a Gene Drive Mouse for Biodiversity Protection” workshop was held on the North Carolina State University campus in Raleigh, NC on March 7-8, 2019, aiming to convene a diverse group of stakeholders, scientists, funders, and leaders for an exploration of perspectives on the development of a gene drive mouse for restoring biodiversity on islands. Information collected at the workshop is presented in this report to inform upcoming decisions by the NCSU-Safe Genes research team about research, testing, and potential deployment of technologies (the Safe Genes program does not fund any environmental releases of gene drive modified organisms), as well as future engagement activities.
Genetic pest management technologies to control invasive rodents
11576D. Kanavy and D. Threadgill, Island invasives: scaling up to meet the challenge, 2019-03-05 15:20:05.
Many strategies exist to manage invasive pests on islands, ranging from poison to trapping, with varying degrees of success. Genetic technologies are increasingly being applied to insect pests, but so far, not to vertebrates. We are implementing a genetic strategy to eradicate invasive mouse populations as another tool for pest control. Mus musculus, the common house mouse, is one of the most widespread invasive species. Mice threaten human health, agriculture, and biodiversity on many islands, particularly seabirds. Seabirds are endangered indirectly through competition for resources or predators being attracted by the mice or directly with mice attacking chicks and eggs. Rodenticides are the most common method of eradicating mice, but their use leads to poisoning of non-target species and has limited efficacy against mice. An approach that could eliminate non-target species impact would be to engineer daughterless mice linked to a gene drive system for self-sustained propagation. For this project, we have investigated exploiting a naturally occurring gene drive, the t-complex. Using the t w2 haplotype of the t-complex, we observed the t w2 haplotype being transmitted to offspring with a transmission distortion ratio of 95.3%. The daughterless phenotype is being accomplished by inserting the Sry gene (male sex-determining gene) into an autosome containing the tw2 haplotype via CRISPR/Cas9 gene editing. The presence of Sry will induce testis formation, regardless of the sex chromosomes naturally inherited. When Sry is inserted into the t-complex, the desired gene will spread through the population, eliminating female offspring. This model system will support studies to evaluate the effectiveness of crashing an invasive population without adversely affecting other
Trialling gene drives to control invasive species: what, where and how?
11573T. Harvey-Samuel, K. J. Campbell, M. Edgington and L. Alphey, Island invasives: scaling up to meet the challenge, 2019-03-05 15:16:48.
The control of invasive species would be enhanced through the addition of novel, more effective and sustainable pest management methods. One control option yet to be trialled in the field is to deploy transgene-based ‘Gene Drives’: technologies which force the inheritance of a genetic construct through the gene pool of a wild population, suppressing it or replacing it with a less harmful form. There is considerable interest in applying gene drives to currently intractable invasives across a broad taxonomic range. However, not all species will make efficient or safe targets for these technologies. Additionally, the safety and efficacy of these systems will vary according to where they are deployed, the specific molecular design chosen, and how these factors interact with the ecology of the target pest. Given the transformative but also controversial nature of gene drives, it is imperative that their first field trials are able to successfully demonstrate that they can be used safely and efficiently. Here, we discuss how to maximise the probability of this outcome through considering three important questions: What types of invasive species should we use to trial gene drives? Where should we be trialling them? and How should these trials be conducted? In particular, we focus on the ecological, genetic and geographic features of small, isolated islands which make them ideal locations for these initial trials. A case study of an island invasive that is deemed highly appropriate for gene drive intervention, and for which gene drive development is currently underway (Mus musculus), is used to further explore these concepts
Towards a genetic approach to invasive rodent eradications: assessing reproductive competitiveness between wild and laboratory mice
11570M. Serr, N. Heard and J. Godwin, Island invasives: scaling up to meet the challenge, 2019-03-05 15:10:12.
House mice are significant invasive pests, particularly on islands without native mammalian predators. As part of a multi-institutional project aimed at suppressing invasive mouse populations on islands, we aim to create heavily male-biased sex ratios with the goal of causing the populations to crash. Effective implementation of this approach will depend on engineered F1 wild-lab males being effective secondary invaders that can mate successfully. As a first step in assessing this possibility, we are characterising genetic and behavioural differences between Mus musculus strains in terms of mating and fecundity using wild house mice derived from an invasive population on the Farallon Islands (MmF), a laboratory strain C57BL/6/129 (tw2), and F1 wild-lab off spring. Mice with the ‘t allele’ (tw2) have a naturally occurring gene drive system. To assess fertility in F1 wild-lab crosses, tw2 males were paired with wild-derived females from the Farallon Islands (MmF). Results of these matings indicate litter sizes are comparable but that weaned pup and adult wild-lab mice are heavier in mass. Next, we initiated tests of male competitiveness using larger (3 m2 ) enclosures with enrichment. We introduced both an MmF and a tw2-bearing male to two MmF females to assess mating outcomes. Preliminary results of these experiments show none of the offspring carried the t-allele. However, performing the same experiment with F1 wildlab males instead of a full lab background resulted in 70% of off spring carrying the t w2 allele. This indicates that F1 wildlab males may be able to successfully compete and secondarily invade. It will be important in subsequent experiments to determine what characteristics contribute to secondary invasion success. More generally, a better understanding of characteristics contributing to overall success in increasingly complex and naturalistic environments will be critical in determining the potential of a gene drive-based eradication approach for invasive mice on islands
A potential new tool for the toolbox: assessing gene drives for eradicating invasive rodent populations
11550K. J. Campbell, J. R. Saah, P. R. Brown, J. Godwin, F. Gould, G. R. Howald, A. Piaggio, P. Thomas, D. M. Tompkins, D. Threadgill, J. Delborne, D. Kanavy, T. Kuiken, H. Packard, M. Serr and A. Shiels, Island invasives: scaling up to meet the challenge, 2019-03-05 14:59:34.
Invasive rodents have significant negative impacts on island biodiversity. All but the smallest of rodent eradications currently rely on island-wide rodenticide applications. Although signifi cant advances have been made in mitigating unintended impacts, rodent eradication on inhabited islands remains extremely challenging. Current tools restrict eradication eff orts to fewer than 15% of islands with critically endangered or endangered species threatened by invasive rodents. The Genetic Biocontrol of Invasive Rodents partnership is an interdisciplinary collaboration to develop and evaluate gene drive technology for eradicating invasive rodent populations on islands. Technological approaches currently being investigated include the production of multiple strains of Mus musculus with a modifi ed form of the native t-complex, or a CRISPR gene drive, carrying genes or mechanisms that determine sex. These systems have the potential to skew the sex ratio of off spring to approach 100% single-sex, which could result in population collapse. One goal proposed is to test the ability of constructs to spread and increase in frequency in M. musculus populations in biosecure, captive settings and undertake modelling to inform development and potential deployment of these systems. Structured ecologically-based risk assessments are proposed, along with social and cultural engagement to assess the acceptability of releasing a gene drive system. Work will be guided by an external ethics advisory board. Partners are from three countries with significant regulatory capacity (USA, Australia, New Zealand). Thus, we will seek data sharing agreements so that results from experiments may be used within all three countries and treat regulatory requirements as a minimum. Species-specific, scalable, and socially acceptable new eradication tools could produce substantial biodiversity benefits not possible with current technologies. Gene drive innovation may provide such a tool for invasive species management and be potentially transformative and worthy of exploring in an inclusive, responsible, and ethical manner.
Controlling invasive rodents via synthetic gene drive and the role of polyandry
3927Manser, AC, S. J.; Sutter, A.; Blondel, D. V.; Serr, M.; Godwin, J.; Price, T. A. R., Proceedings of the Royal Society B-Biological Sciences, 286:9. 2019-01-05 00:00:00.
House mice are a major ecosystem pest, particularly threatening island ecosystems as a non-native invasive species. Rapid advances in synthetic biology offer new avenues to control pest species for biodiversity conservation. Recently, a synthetic sperm-killing gene drive construct called t-Sry has been proposed as a means to eradicate target mouse populations owing to a lack of females. A factor that has received little attention in the discussion surrounding such drive applications is polyandry. Previous research has demonstrated that sperm-killing drivers are extremely damaging to a male's sperm competitive ability. Here, we examine the importance of this effect on the t-Sry system using a theoretical model. We find that polyandry substantially hampers the spread of t-Sry such that release efforts have to be increased three-to sixfold for successful eradication. We discuss the implications of our finding for potential pest control programmes, the risk of drive spread beyond the target population, and the emergence of drive resistance. Our work highlights that a solid understanding of the forces that determine drive dynamics in a natural setting is key for successful drive application, and that exploring the natural diversity of gene drives may inform effective gene drive design.
Invasion Success and Management Strategies for Social Vespula Wasps
13740P. J. Lester and J. R. Beggs, Annual Review of Entomology, 64:51-71. 2018-09-26 19:38:03.
Three species of Vespula have become invasive in Australia, Hawai'i, New Zealand, and North and South America and continue to spread. Economically, their main negative effect is associated with pollination and the apicultural industry. Climate change is likely to exacerbate their impacts in many regions. Although investigated extensively, no effective biological control agents have yet been found. Emerging technologies such as gene drives are under consideration.
A sustainable synthetic biology approach for the control of the invasive golden mussel (Limnoperna fortunei)
19204M. F. Rebelo, L. F. Afonso, J. A. Americo, L. da Silva, J. L. B. Neto, F. Dondero and Q. Zhang, PeerJ Preprints, 6:e27164v3. 2018-09-12 14:52:07.
The recent development of the CRISPR-Cas9-based gene drive has created the conditions to seriously consider this technology to solve one of the major environmental challenges in biodiversity conservation i.e. the control of invasive species. There is no efficient control method for golden mussel infestation available so far. Here we discuss the technical and economic feasibility of using a synthetic biology based approach to fight and control the invasive mussel Limnoperna fortunei in South American rivers and reservoirs.
Identifying knowledge gaps for gene drive research to control invasive animal species: The next CRISPR step
3998Moro, DB, Margaret; Kennedy, Malcolm; Campbell, Susan; Tizard, Mark, Global Ecology and Conservation, 13:e00363. 2018-01-16 00:00:00.
Invasive animals have been linked to the extinctions of native wildlife, and to significant agricultural financial losses or impacts. Current approaches to control invasive species require ongoing resources and management over large geographic scales, and often result in the short-term suppression of populations. New and innovative approaches are warranted. Recently, the RNA guided gene drive system based on CRISPR/Cas9 is being proposed as a potential gene editing tool that could be used by wildlife managers as a nonlethal addition or alternative to help reduce pest animal populations. While regulatory control and social acceptance are crucial issues that must be addressed, there is an opportunity now to identify the knowledge and research gaps that exist for some important invasive species. Here we systematically determine the knowledge gaps for pest species for which gene drives could potentially be applied. We apply a conceptual ecological risk framework within the gene drive context within an Australian environment to identify key requirements for undertaking work on seven exemplar invasive species in Australia. This framework allows an evaluation of the potential research on an invasive species of interest and within a gene drive and risk context. We consider the currently available biological, genetic and ecological information for the house mouse, European red fox, feral cat, European rabbit, cane toad, black rat and European starling to evaluate knowledge gaps and identify candidate species for future research. We discuss these findings in the context of future thematic areas of research worth pursuing in preparation for a more formal assessment of the use of gene drives as a novel strategy for the control of these and other invasive species.
Economic issues to consider for gene drives
3997Mitchell, PDB, Z.; McRoberts, N., Journal of Responsible Innovation, 5:S180-S202. 2018-01-15 00:00:00.
We examine four economic issues regarding gene drive applications made possible by gene editing technologies. First, whether gene drives are self-sustaining or self-limiting will largely determine which types of organizations have incentives to develop and deploy gene drives and greatly influence their governance and regulation. Social factors will also play key roles, particularly public perceptions, with these perceptions co-determined with regulation and governance. Second, gene drive applications will generate unintended negative social impacts that will partially offset benefits. Third, economic surplus, the traditional measure of economic benefits, incompletely captures the welfare impacts of gene drive applications. Fourth, gene drives imply dynamic nonlinearities that make identifying economic equilibria and general policy recommendations challenging. The potentially substantial benefits, coupled with the technical, social, and economic uncertainties surrounding gene drives, suggest that a responsible course of action is to move forward while maintaining regulatory flexibility and conducting research to resolve key uncertainties.
Trojan Females and Judas Goats: Evolutionary Traps as Tools in Wildlife Management
13743B. A. Robertson, R. S. Ostfeld and F. Keesing, Bioscience, 67:982-993. 2017-11-01 19:42:43.
Here, we bring together science from the pest-control, eco-evolutionary, and conservation communities to outline how evolutionary traps can be repurposed to eliminate or control pest species. We highlight case studies and devise strategies for the selection of appropriate cues to manipulate, traits to target, and mechanisms to use in setting evolutionary traps that will most rapidly reduce animal abundance while preventing evolutionary escape. We find that evolutionary traps are demonstrably effective and unique tools with high target-species specificity that are deployable in concert with more traditional approaches.
Could genetic engineering save the Galapagos?
14868S. S. Hall, Scientific American, 2017-11-01 19:26:09.
Campbell has been working on eradications in the Galápagos since 1997, including a 2006 campaign to remove all the feral goats and donkeys from Floreana. A decade later he’s a project manager with Island Conservation, and the most ambitious project on its agenda is once again on Floreana: to eradicate every single rat and mouse on the island.
The potential for the use of gene drives for pest control in New Zealand: a perspective
14253P. K. Dearden, N. J. Gemmell, O. R. Mercier, P. J. Lester, M. J. Scott, R. D. Newcomb, T. R. Buckley, J. M. E. Jacobs, S. G. Goldson and D. R. Penman, Journal of the Royal Society of New Zealand, 48:225-244. 2017-10-25 14:20:45.
Here we describe the current state of gene drive technologies and present a series of examples to examine the potential benefits and problems arising from gene drive approaches for pest control in New Zealand.
The sterile male release approach as a method to control invasive amphibian populations: a preliminary study on Lithobates catesbeianus
13727S. Descamps and A. De Vocht, Management of Biological Invasions, 8:361-370. 2017-09-14 18:55:55.
Widespread populations of the invasive species Lithobates catesbeianus (American bullfrog) are present in different parts of the world and are difficult to control. This study investigated the possibility to sterilize male individuals of this species in order to use the sterile male release technique in controlling these invasive populations.
The optimal implementation of the Trojan Y chromosome eradication strategy of invasive species
11510M. R. Kelly and X. Y. Wang, Journal of Biological Systems, 25:399-418. 2017-08-02 15:25:17.
Invasive aquatic species continue to be a persistent problem around the world. The Trojan Y Chromosome (TYC) eradication strategy has recently been developed to help fight the problem in aquatic systems by targeting only the invasive species, sparing native marine stock. It involves rearing genetically modified samples of the invasive species and introducing them into the environment to alter the sex ratio of the invasive population. The paper is devoted to finding the optimal implementation of the TYC eradication strategy of an invasive species as well as a modified, potentially more cost-effective strategy. The modified TYC strategy (MTYC) eliminates one round of exposure to sex hormones compared to the TYC strategy. After introducing both strategies, the optimal control problems for each are formulated. The two strategies are compared through numerical simulations. Our results illustrate that the MTYC strategy, with lower implementation costs, is a better strategy option when trying to minimize the overall effective cost in most scenarios.
What’s the story with genetic pest management (GPM)?
11584K. Guthrie, Predator Free NZ, 2017-07-13 15:30:50.
Breakthrough genetic technologies are likely to play a key role in achieving a predator-free future. But it’s important that we understand what the various technologies are now – as they’re being developed – not when they’re about to be implemented. We need to debate the issues and become as informed as possible; to know if there are risks involved in particular techniques and what safeguards will be in place. We need to be able to make informed choices, once such choices become possible. Not all genetic techniques, for example, involve ‘genetic engineering’.
The use of gene editing to create gene drives for pest control in New Zealand
16070Royal Society Te Apārangi Gene Editing Panel, Royal Society of New Zealand, 2017-06-06 13:54:28.
to explore the implications of gene editing technology for New Zealand, the Royal Society Te Apārangi has convened a multidisciplinary panel of some of New Zealand’s leading experts to consider the social, cultural, legal and economic implications of revolutionary gene-editing technologies for New Zealand to: • Raise awareness of the scientific possibilities and associated public issues of new gene editing technologies to inform debate • Provide information and guidance for policy makers to address current and new issues needing to be clarified or resolved • Show where gene-editing applications are covered by established policies and regulations and where changes are needed • Provide a New Zealand perspective to the global discussion on this technology and identify where global consensus is important T
Towards the genetic control of invasive species
4047Harvey-Samuel, TA, T.; Alphey, L., Biological Invasions, 19:1683-1703. 2017-01-05 00:00:00.
Invasive species remain one of the greatest threats to global biodiversity. Their control would be enhanced through the development of more effective and sustainable pest management strategies. Recently, a novel form of genetic pest management (GPM) has been developed in which the mating behaviour of insect pests is exploited to introduce genetically engineered DNA sequences into wild conspecific populations. These 'transgenes' work in one or more ways to reduce the damage caused by a particular pest, for example reducing its density, or its ability to vector disease. Although currently being developed for use against economically important insect pests, these technologies would be highly appropriate for application against invasive species that threaten biodiversity. Importantly, these technologies have begun to advance in scope beyond insects to vertebrates, which include some of the world's worst invasives. Here we review the current state of this rapidly progressing field and, using an established set of eradication criteria, discuss the characteristics which make GPM technologies suitable for application against invasive pests.
Invertebrate Biosecurity Challenges in High-Productivity Grassland: The New Zealand Example
13738S. L. Goldson, B. I. P. Barratt and K. F. Armstrong, Frontiers in Plant Science, 7. 2016-11-15 19:35:24.
This review explores the unique challenges faced by pasture biosecurity and what may be done to confront existing difficulties. While there is no silver bullet, and limited opportunity pre and at for improving pasture biosecurity, advancement may include increased and informed vigilance by farmers, pheromone traps and resistant plants to slow invasion. Increasingly, there is also the potential for more use of improved population dispersal models and surveillance strategies including unmanned aerial vehicles, as well as emerging techniques to determine invasive pest genomes and their geographical origins.
Stochastic models for the Trojan Y-Chromosome eradication strategy of an invasive species
11514X. Y. Wang, J. R. Walton and R. D. Parshad, Journal of Biological Dynamics, 10:179-199. 2015-12-16 15:32:37.
The Trojan Y-Chromosome (TYC) strategy, an autocidal genetic bio-control method, has been proposed to eliminate invasive alien species. In this work, we develop a Markov jump process model for this strategy, and we verify that there is a positive probability for wild-type females going extinct within a finite time. Moreover, when sex-reversed Trojan females are introduced at a constant population size, we formulate a stochastic differential equation (SDE) model as an approximation to the proposed Markov jump process model. Using the SDE model, we investigate the probability distribution and expectation of the extinction time of wild-type females by solving Kolmogorov equations associated with these statistics. The results indicate how the probability distribution and expectation of the extinction time are shaped by the initial conditions and the model parameters.
Genetic Engineering to the Rescue Against Invasive
11591K. Langin, National Geographic, 2014-07-18 15:37:46.
Genes for swatting tiger mosquitoes, defanging brown tree snakes, and deporting Asian carp, all nasty invasive species, sound like a swell idea. But the latest idea in eradication—genetic engineering—poses its own risks, warn biotechnology experts. Invasive species wreak havoc worldwide, disrupting native ecosystems and inflicting more than $120 billion in damages annually in the U.S. alone. Many economically—and environmentally—damaging species, such as those mosquitoes, snakes, and carp, defy removal with existing technology.
Combining the Trojan Y chromosome and daughterless carp eradication strategies
11522J. L. Teem and J. B. Gutierrez, Biological Invasions, 16:1231-1240. 2013-05-17 15:50:22.
The Trojan Y chromosome (TYC) strategy and the daughterless carp (DC) strategy represent two autocidal genetic biocontrol methods for eliminating invasive fish by changing the sex ratio of the population. Each strategy is designed to reduce the number of females in a target population, ultimately leading to local extinction of the population. In the DC approach, the proportion of males in the population is increased as a result of introducing an autocidal fish containing a transgenic aromatase gene insertion into multiple autosome sites. In the TYC approach, matings of an autocidal fish containing two Y sex chromosomes results in an increased proportion of males in the population. A mathematical model based upon coupled ordinary differential equations was constructed to observe the effect of an autocidal fish with the combined genetic features of both strategies (TYCDC) on a target population. The model incorporated a fitness parameter associated with fish bearing aromatase inhibitor genes and for fish bearing two Y chromosomes. Under conditions where the fitness penalty of the autocidal fish was negligible, modeling results showed that a combined strategy produced a modest reduction in the time required for female eradication, and that fewer autocidal fish were required to achieve extinction. However, increasing the fitness penalty associated with the autocidal fish neutralized the benefits of the TYCDC strategy, and suggested that the effort and expense of a combined strategy may not be warranted if the fitness cost of the TYCDC autocidal fish is significant.
A comparison of the Trojan Y Chromosome and daughterless carp eradication strategies
11520J. L. Teem, J. B. Gutierrez and R. D. Parshad, 16, 16:1217-1230. 2013-05-08 15:46:59.
Two autocidal genetic biocontrol methods have been proposed as a means to eliminate invasive fish by changing the sex ratio of the population: the Trojan Y Chromosome (TYC) strategy and the Daughterless Carp (DC) strategy. Both strategies were modeled using ordinary differential equations that allow the kinetics of female decline to be assessed under identical modeling conditions. When compared directly in an ordinary differential equation (ODE) model, the TYC strategy was found to result in female extinction more rapidly than a DC strategy (in each of three models tested in which the Daughterless autocidal fish contained an aromatase inhibitor gene in either two or eight copies). The TYC strategy additionally required the introduction of fewer autocidal fish to the target population to achieve local extinction of females as compared to the DC approach. The results suggest that the relatively lower efficiency of female reduction associated with the DC approach is a consequence of a greater capacity to produce females and also a reduced capacity to produce males as compared to the TYC system.
Analysis of the Trojan Y chromosome model for eradication of invasive species in a dendritic riverine system
11532J. B. Gutierrez, M. K. Hurdal, R. D. Parshad and J. L. Teem, Journal of Mathematical Biology, 64:319-340. 2011-03-04 17:07:15.
The use of Trojan Y chromosomes has been proposed as a genetic strategy for the eradication of invasive species. The strategy is particularly relevant to invasive fish species that have XY sex determination system and are amenable to sex-reversal. In this paper we study the dynamics of an invasive fish population occupying a dendritic domain in which Trojan individuals bearing multiple Y chromosomes have been released as a means of eradication. We demonstrate the existence of a bounded absorbing set that represents extinction of the invasive species irrespective of the dendritic configuration. The method of analysis used to obtain global estimates could be applied to other population problems and other geometries.
On the global attractor of the Trojan Y chromosome model.
11536R. D. Parshad and J. B. Gutierrez, Communications on Pure and Applied Analysis, 10:339-359. 2010-01-01 17:11:02.
We consider the Trojan Y Chromosome (TYC) model for eradication of invasive species in population dynamics. We present global estimates for the TYC system in a spatial domain. In this work we prove the existence of a global attractor for the system. We derive uniform estimates to tackle the question of asymptotic compactness of the semi-group for the TYC model in H(2)(Omega). This along with the existence of a bounded absorbing set, which we also derive, demonstrates the existence of a global attractor for the TYC model. The present analysis reveals that extinction of an invasive species is always possible to achieve irrespective of geometric considerations of the domain. This result is valid for TYC systems in which advection is negligible. This theoretical work lays the foundation for experimental studies of the application of the TYC eradication strategy in spatial ecology, since the outcome is in principle guaranteed.
Genetic control of invasive plants species using selfish genetic elements
13612K. A. Hodgins, L. Rieseberg and S. P. Otto, Evolutionary Applications, 2:555-569. 2009-10-30 13:00:19.
Invasive plants cause substantial environmental damage and economic loss. Here, we explore the possibility that a selfish genetic element found in plants called cytoplasmic male sterility (CMS) could be exploited for weed control. We developed an analytical model and a spatial simulation to assess the use of CMS alleles to manage weed populations.
Control of introduced species using Trojan sex chromosomes
11543S. Cotton and C. Wedekind, Trends in Ecology & Evolution, 22:441-443. 2007-07-20 17:25:46.
To control introduced exotic species that have predominantly genetic, but environmentally reversible, sex determination (e.g. many species of fish), Gutierrez and Teem recently modeled the use of carriers of Trojan Y chromosomes - individuals who are phenotypically sex reversed from their genotype. Repeated introduction of YY females into wild populations should produce extreme male-biased sex ratios and eventual elimination of XX females, thus leading to population extinction. Analogous dynamics are expected in systems in which sex determination is influenced by one or a few major genes on autosomes.
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National Institutes of Health
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