The Island Premise: Why Gene Drives for Rodents Are Designed for Places Unlike Winnipeg

1. Introduction: a technology with an address

Rodent control in this journal has been a story of mortality: traps, baits and exclusion, against a population that replaces what is removed. Gene drives propose something different, changing what the population is rather than how many of it there are.

1.1 The address is in the first sentence

The case for these tools is made about islands, and the design choices follow from that setting.

1.2 What this article argues

That the island setting carries four premises, a closed population, decades of patience, local consent and acceptance of irreversibility, and that a city offers none of them. Sections 12 to 19 are the case.

1.3 What it does not argue

That the technology is bad, or that island work should not proceed. Nothing here disputes that invasive rodents devastate island species.³

2. What a gene drive is

Inheritance, biased.

A gene drive biases the transmission of one of the two copies of a gene so that it is inherited more frequently than by random segregation.⁶

2.1 Why that matters

An ordinary harmful gene is removed by selection. A drive can spread through a population despite imposing a fitness cost, which is what makes suppression conceivable.⁹

2.2 The insect precedent

Highly efficient CRISPR drive systems were developed in insects before any mammal, using targeted DNA cleavage and homology-directed repair to convert heterozygous genotypes to homozygosity.⁶

2.3 And the laboratory motive was different

The 2019 mouse work was pitched at laboratory genetics: a working drive would let researchers assemble multi-gene genotypes that are currently impractical because of the numbers of animals required.⁶ One commentary notes that with three independent alleles, 146 offspring are needed for a 90 per cent chance of producing a single animal with the wanted genotype.²²

2.4 The two motives share a mechanism

Which is why a paper about breeding laboratory mice more efficiently also contributed, in its authors' words, to the debate about combating invasive rodent populations in island communities.²³

3. The natural drive it borrows

Mice already have one.

The t haplotype is a naturally occurring male meiotic drive in mice, transmitted at a strongly biased rate, and the tCRISPR authors note that this bias could be leveraged for population suppression or eradication on islands.³

3.1 Which has been modelled before

Earlier modelling suggested that non-lethal t haplotypes could cause eradication in small populations through male sterility.³

3.2 And works without engineering, slowly

One account reports that adding mice carrying the ordinary t haplotype could collapse the modelled population in about 43 years, against roughly 25 with the CRISPR element added.⁴

4. What tCRISPR does

The design.

A CRISPR transgene is embedded in the t haplotype and targets a female fertility gene that needs only one working copy, so fertile females are progressively depleted as the drive spreads.³

4.1 In the developers' words

The approach combines a naturally occurring gene drive with DNA editing to alter a fertility gene and progressively affect the population's ability to reproduce.¹

4.2 Without toxins

The lead researcher describes it as a humane approach to controlling invasive mice without releasing toxins into the environment.¹

4.3 Which is the comparison being invited

Not against doing nothing, but against rodenticide, which our bromethalin article described as carrying its own costs.

That framing is ours.

5. The modelling result

Spatially explicit individual-based modelling on a hypothetical island indicated eradication potential across a range of realistic scenarios.³ Accounts of the study report about 250 modified mice eradicating 200,000 in around 20 years,¹ and 256 mice driving the population to zero in around 25 years.⁴

5.1 Two numbers, one study

We report both rather than choosing, since we could not read the paper's full results and the difference may reflect different scenarios within the same modelling.

5.2 What the model is

A simulation of a hypothetical island, not a measurement of any real population.³

5.3 Two hundred thousand mice is a large island

The modelled population is bigger than most island mouse populations that have been cleared by conventional means, which is the point: the technology is aimed at the cases current methods cannot reach.²

The first clause is our characterisation and we did not verify it against eradication records.

6. What was actually built

Less than the model describes.

The authors demonstrated feasibility by engineering and testing tCRISPR in a genetically contained split drive format, with the Cas9 and guide RNA cassettes on different chromosomes.³

6.1 Why a split drive is contained

Separating the two components means they segregate independently, so the construct does not propagate as a single unit. A news account reports that the altered mice passed on the new genetics 95 per cent of the time.⁴

6.2 The distance from here to a release

A contained laboratory construct and a modelled island are both some way from an approved field release, which §17 shows can fail on grounds that have nothing to do with the biology.

That observation is ours.

7. The first mammalian test

A 2019 study used an element encoding a guide RNA embedded in the mouse tyrosinase gene to test whether targeted gene conversion occurs when CRISPR is active in the early embryo or the developing germline.⁶

7.1 The result

Although Cas9 efficiently induced double-stranded breaks in the early embryo and male germline, those breaks were not corrected by homology-directed repair. In the female germline they were, copying the element to the other chromosome and increasing its inheritance.⁷

7.2 How much

A later paper by an overlapping group describes the 2019 work as achieving an average gene conversion rate of 72 per cent in the female germline.⁸

7.3 Which is super-Mendelian but not complete

Well above the 50 per cent of ordinary inheritance, and well below the near-total conversion reported in some insect systems.⁶

7.4 What was measured

The element carried a guide RNA and a fluorescent marker inserted into an exon of the tyrosinase gene, disrupting it, so conversion showed up as coat colour.²² Using a visible pigment gene meant the result could be read off the animal rather than inferred.

The second sentence is ours.

7.5 A later study extended it

Work using Cas9 expressed during meiosis reported gene conversion in the male as well as the female germline,⁸ so the 2019 asymmetry reflected when Cas9 was active rather than a fixed property of male mice.

The inference in the second half of that sentence is ours.

8. Why the sex asymmetry matters

Our reading.

A drive that copies only in females has half the opportunities of one that copies in both sexes, which is one reason the tCRISPR design uses a natural male drive to do the spreading and CRISPR only to damage fertility.³

8.1 A division of labour

One review describes the tCRISPR idea as clever precisely because it uses CRISPR not to spread the construct but to damage genes needed for female fertility.⁴

9. Other rodent drive designs

The field is not one approach.

A consortium member's team has worked on modifying the t haplotype to create daughterless mice, where females carrying two copies give birth only to males, potentially crashing the population.⁵

9.1 And modelled alternatives

Modelling work has simulated homing drives and X chromosome shredding drives for eradicating island mice, and concluded both could be used against large populations.⁹

9.2 With efficiency thresholds

A machine-learning modelling study of three suppression drives found one that at 84 per cent efficiency produced complete suppression in 2 per cent of simulations, rising to 100 per cent of simulations at 87 per cent efficiency.¹⁰

9.3 A three-point difference decides the outcome

Which means the difference between a drive that works and one that mostly does not can be a few percentage points of laboratory performance.

That reading is ours.

9.4 And the consortium is explicit that this is one option

Its coordinator describes the technology as a complementary tool to help address invasive mice, rather than a replacement for existing eradication methods.²⁴

10. The island case

Why the work is funded.

Invasive mice are described as a significant cause of species extinctions globally and a particular threat to island ecosystems, with hundreds of successful rodent eradications on islands among the most impactful conservation actions available.²

10.1 And a stated limit

The same source says that with methods available today it is feasible to restore only about 15 per cent of the world's islands.²

10.2 Which is the gap the technology addresses

Not islands that can already be cleared, but the ones that cannot.

11. Why islands and not everywhere

Stated by a participant.

A conservation organisation's director explains that rodenticides which have eliminated mice and rats on small islands are too risky to use on larger islands with complex ecosystems and large human populations.⁵

11.1 So the comparison is with poison, not with nothing

The argument is that a drive might reach places a bait station cannot.

11.2 The comparison this journal has already made

Our bromethalin article described how removing one class of rodenticide from consumer shelves moved households onto a chemistry with no antidote, and our translocation article described live removal failing on its own terms. Neither conclusion says the alternative is costless.

11.3 So a new method is measured against a flawed incumbent

Which is the fair comparison, and also the one most likely to flatter anything new.

Sections 11.2 and 11.3 are ours.

12. The first premise: a closed population

Our argument.

Every modelled eradication assumes the population does not receive migrants. On an island that assumption is geography; in a city it is false. Our translocation article described the vacancy effect, where removing an animal invites another into the territory it held.

12.1 And our own city article said the same of rats

The Alberta rat programme worked because three of the province's borders were closed by mountains, forest and grassland, as our prairie rat article set out. A neighbourhood has no such border.

12.2 What closure actually means

Not that no animal ever crosses, but that crossings are rare enough that the population's genetics are determined from within. A drive released into a population receiving regular migrants is diluted by animals that carry none of it.

12.3 Cities are the opposite case

Mice move between adjoining buildings, along services and with goods. Our article on vacant properties described a rodent source next door that the complaint process cannot reach, which is the ordinary urban situation: the population a treatment addresses is not bounded by the property line.

12.4 And a house is not a population

The unit a drive acts on is a breeding population, while the unit a customer buys is a building. The two do not correspond, and nothing in the technology closes that gap.

Sections 12.2 to 12.4 are our reasoning.

13. What immigration does to a slow method

Also ours.

A method that takes decades has to outpace replacement for the whole period. A method that takes a week, such as a bait programme in a single building, only has to outpace it briefly.

13.1 Which is why scale and closure go together

The slower the method, the larger the closed area it needs, and a drive is the slowest method this journal has examined.

13.2 Modellers treat space as decisive

Which is consistent with the modelling literature, where the spatial ecology of the target population interacts with drive efficiency to determine the outcome.⁹

14. The second premise: decades

Stated by the researchers.

The lead researcher acknowledged that 25 years is a long wait for some endangered island populations, said the team would love to see it work faster, and called it a work in progress.⁴

14.1 That is the optimistic figure

It is the modelled time to zero under the scenarios the authors simulated.³

14.2 And the unmodified comparison is longer still

The ordinary t haplotype without the CRISPR element was modelled as taking about 43 years to collapse the same population,⁴ so the engineering buys roughly two decades against a natural drive that already exists.

14.3 Which is a useful way to read the claim

The technology is not the difference between control and no control. It is the difference between a very long process and a somewhat less long one.

That framing is ours.

15. Against the timescale of a rodent problem

Ours.

A household with mice wants them gone this month. A property manager wants an inspection record this quarter. Nothing in structural pest control operates on a horizon where a twenty-five-year population trajectory is the deliverable.

15.1 So this is not a competing product

It is a conservation tool for a setting where the alternative is extinction of a seabird colony, not a service a customer could buy.

15.2 Nor a public programme

A municipal rodent programme is funded annually and judged on complaints within the year, so a method whose first measurable effect arrives after several council terms has no natural sponsor.

15.3 Which is not an argument that long methods are wrong

Our screwworm article described a programme sustained across decades. It is an argument that the sponsor has to be an institution capable of that horizon, and pest control customers are not.

16. The third premise: consent

Which the developers treat as integral.

The tCRISPR team says its broader project includes consideration of societal views and attitudes, integral to its ongoing research.¹ The lead researcher also noted the intention to consult people living in the area, as was done for modified mosquito releases elsewhere.⁴

16.1 Consent is not a formality

Because a release changes the environment of people who did not choose it, and because, as §17 shows, approval can be withdrawn after it is given.

16.2 Consent for what, exactly

A release is not a treatment of a property. It changes animals that move across properties, so the people affected are not the people who agreed, which is what makes community consultation the relevant unit rather than a customer signature.

That distinction is ours.

16.3 The developers accept the framing

Their stated intention is to consult people living in the area, and their broader project treats societal views as integral rather than incidental.¹⁴

17. Burkina Faso, August 2025

A malaria project released about 16,000 genetically modified male mosquitoes in a village on 11 August 2025, the first release of its kind on the African continent, after authorisation from three regulators.¹⁵

17.1 The reversal

On 18 August the national authorities asked the team to suspend all activities; the project says the release had taken place in accord with the terms of its permits and that it had operated in compliance with national law since 2012.¹¹

17.2 Then the shutdown

On 22 August the responsible ministry announced that all the project's activities had been halted across the national territory, that facilities holding modified mosquitoes had been sealed since 18 August, and that remaining samples would be destroyed under a prescribed protocol.¹⁴

17.3 And the reversal of the release itself

A science news report describes researchers killing the mosquitoes in their insectary and the government sending a team to spray insecticide in the village to kill those released.¹²

17.4 The researchers did not know why

The same report quotes the project's global principal investigator saying they were waiting to find out what was going on and trying to find the rationale.¹²

17.5 With effects elsewhere

A journal's news service reports that the suspension disrupted plans by scientists in Uganda working on their own modified mosquitoes.¹³

18. What that case does and does not show

Read carefully.

The mosquitoes released were not gene drive organisms. The project describes them as non gene drive genetically modified male bias mosquitoes,¹¹ released to gain knowledge and experience before any later drive release.¹⁶

18.1 So the precedent is about permission, not about drives

A project that had regulatory approval, ethics approval and village agreement was stopped in eleven days and its work destroyed. Whatever the merits, that is the political risk attached to any open release.

18.2 And accounts of why differ

One advocacy account presents the halt as a victory for opponents of open-field releases and cites both local opposition and technical criticism.¹⁷ A trade summary reports only the sequence of approval and suspension.¹⁸ We have no authoritative statement of the government's reasoning.

18.3 We report it as an event, not a verdict

Sections 18.1 and 18.3 are ours.

18.4 And the sequence is agreed across sources

The project, a news agency, a trade newsletter, an advocacy group and a science journal all report the same dates of release, sealing and suspension, differing in emphasis rather than in chronology.^1114181612 One advocacy account gives a much larger release figure than the others, which we note rather than adopt.¹⁷

19. The fourth premise: irreversibility

The structural difference.

A bait station can be removed, a trap unset, a treatment discontinued, and our resistance reversion article described populations drifting back after a chemistry is withdrawn. A drive that has spread cannot be collected up.

19.1 Containment is designed in for that reason

The split-drive format used in the laboratory exists precisely to keep the construct from spreading.³

19.2 And specificity is the proposed safeguard

The lead researcher suggests a final version might target mutations occurring only on one island, so that a mouse escaping to the mainland would have no effect on local mice.⁴

19.3 Which concedes the point

Designing for the escape case is an acknowledgement that recall is not available.

That reading is ours.

19.4 What reversibility is worth

Our article on resistance reversion found that withdrawing a chemistry sometimes lets susceptibility return, which is only possible because the intervention can be stopped. A drive removes that option from the toolkit, and the option has had value in this journal's own material.

That valuation is ours.

20. How drives fail technically

The developers say they are working on strategies to prevent failed eradication due to the emergence of gene drive resistance in the target population.¹

20.1 Efficiency is the pivot

The modelling literature treats drive efficiency as interacting with the spatial ecology of the target population,⁹ and one study found a three-point change in efficiency separating near-total failure from near-total success.¹⁰

20.2 Which is a laboratory number applied to a field population

A construct's conversion rate is measured in cages, and the models then ask what that rate does over decades in the wild.

That observation is ours.

21. Resistance, again

A familiar shape.

A drive that cuts a target sequence selects for versions of that sequence it cannot cut, which is the same logic this journal has described for insecticides and rodenticides: the control agent selects for whatever survives it.

21.1 Except the timescale is the drive's own

Here resistance has decades in which to appear, because that is how long the method takes.

Sections 21 and 21.1 are our reasoning, though resistance is named as a problem by the developers themselves.¹

21.2 And mating behaviour can dilute a drive

Modelling has considered polyandrous mating and sperm competition, which could compromise the efficacy of some strategies.⁹

21.3 And a resistant allele spreads on its own

An animal carrying a sequence the drive cannot cut passes on a normal working fertility gene while its neighbours lose theirs, so the population selects strongly for exactly the variant that defeats the method. That is the same structure as insecticide resistance, compressed into fewer generations of selection but stretched over more years.

That description is our reasoning applied to a problem the developers name themselves.¹

22. Specificity and escape

A design goal, not a guarantee.

A collaborating agency scientist describes the prototype as designed to be highly specific for mice, and as evidence that drives can be developed against other species.¹

22.1 Which cuts both ways

The same sentence that reassures about this construct advertises the generality of the method.

That observation is ours.

22.2 The word prototype is doing work

A construct described as a prototype is, by its own account, not the thing that would be released, so specificity claims attach to a design rather than to a finished tool.

That reading is ours.

23. What Canadian regulation would require

The framework that would apply.

Under Part 6 of the federal environmental protection act and the New Substances Notification Regulations (Organisms), anyone manufacturing or importing a living organism new to Canada must notify the federal environment department, and living organisms include higher organisms such as insects and animals, genetically modified or not.¹⁹

23.1 With a joint assessment

The environment department and the health department conduct a joint assessment of potential risk to the environment, biodiversity and human health.²⁰

23.2 And mandatory public consultation for vertebrates

Amendments that received royal assent in June 2023 made consultation mandatory when the programme assesses a vertebrate animal or a prescribed living organism before the end of the assessment period.²¹

23.3 Which is the consent premise, in statute

A modified mouse is a vertebrate, so the consultation requirement would apply.

That application is ours; we found no Canadian assessment of any gene drive organism.

23.4 An exemption worth noting

The requirements do not apply to organisms imported or manufactured for a use regulated under one of the acts listed in a schedule to the environmental act, which includes the Pest Control Products Act.²⁰ Which regime would govern a modified rodent intended for pest control, rather than conservation, is not something we could establish.

23.5 The regulations are being rewritten

The federal government has been reviewing and modernising these regulations since 2021, with stated objectives including enhanced protection of biodiversity and stronger openness of regulatory oversight.²⁵

24. Against fertility control

The nearest relative in this journal.

Our two articles on contraceptive bait examined a registered product that depletes ovarian follicles and disrupts sperm production. A drive targeting a female fertility gene attacks the same demographic variable by a different route.

24.1 With opposite delivery problems

Contraceptive bait must be eaten repeatedly by enough animals to matter, and stops working when baiting stops. A drive is delivered once and then delivers itself, which is its advantage and the source of §19.

24.2 And a shared arithmetic

Both attack reproduction rather than mortality, which is the response to the rebound problem our earlier work described.

Sections 24 to 24.2 are our comparison.

24.3 And a difference in who decides

Contraceptive bait is bought and deployed by a property owner on their own property. A drive is released into a landscape by an institution, which is a different kind of decision with a different set of people affected.

That contrast is ours.

25. Against the eradication literature

Our screwworm article's lesson.

Sterile insect technique cleared a continent of screwworm and then required a permanently maintained barrier, because eradication inside a boundary holds only while something prevents re-entry across it.

25.1 The same condition applies here

An island drive that succeeds leaves an island that can be reinvaded by a pregnant mouse in a cargo container. The technology changes how a population is cleared, not whether the boundary has to be kept.

That parallel is ours.

26. What we take from it

Three things.

The design is for closed populations on long horizons. Sections 10 to 14.³²

A city supplies neither. Sections 12 and 13, which are our argument.

And permission is the fragile part. Section 17.¹¹¹⁴

26.1 And one thing we are not claiming

That the premises cannot be met anywhere. They are met on some islands, which is why that is where the work is aimed.²³

27. Our own position

The disclosure.

This company sells rodent control by conventional means, so a technology presented as replacing toxins is one we have an interest in reading sceptically. We have tried to state the developers' claims in their own terms and to mark our disagreements as ours.

28. The Manitoba position

28.1 Nothing here is local

We found no Canadian field programme, and no Manitoba involvement in any rodent gene drive work.

28.2 The regulatory path exists anyway

Any such organism would be assessed federally under the framework in §23.¹⁹²⁰

28.3 And the province's rodent problem is an open one

Our prairie rat article described Manitoba as a province without closed borders, which is the condition §12 says a drive needs.

28.4 And the nearest local parallel is a barrier, not a technology

Alberta holds its rat-free status by inspection and killing along a control zone, maintained indefinitely, which is the same structure our screwworm article described. Whatever clears a population, something has to keep it clear.

29. Limitations and open questions

We read the key paper as its significance statement. The tCRISPR results reach us through the paper's abstract and significance section, news coverage and consortium releases, so the modelling assumptions are not in front of us.³⁴

The headline figures disagree. Accounts give about 250 mice and 20 years, and 256 mice and 25 years, and we could not resolve which scenario each describes.¹⁴

Several sources are participants. The consortium, the conservation organisation and the gene drive network all advocate for this work, and are flagged in the references.²¹⁶

And one is an opponent. The account presenting the Burkina Faso halt as a victory is advocacy material and flagged as such.¹⁷

The Burkina Faso reasoning is unknown to us. We have the sequence of events from the project, the ministry as reported and news coverage, but no authoritative statement of why the government acted.¹¹¹²¹⁴

Sections 4.3, 6.2, 7.4, 7.5, 8, 9.3, 11.2, 11.3, 12, 13, 15, 14.3, 16.1, 16.2, 18.1, 18.3, 22.2, 19.3, 20.2, 21, 22.1, 23.3, 21.3, 24, 25 and 28.4 are our reasoning. The four premises, the city argument and the comparisons with fertility control and screwworm are ours rather than sourced positions.

30. Conclusion

The leading rodent gene drive puts a CRISPR element inside a natural mouse meiotic drive so that it spreads through males while sterilising females, and modelling of a hypothetical island suggests a few hundred modified animals could clear two hundred thousand in twenty to twenty-five years. What exists in the laboratory is a contained split-drive version, and the first mammalian test of CRISPR copying, in 2019, worked in the female germline at around 72 per cent and not at all in the male germline or the early embryo.³⁴⁷⁸

The case for the work is explicitly about islands, where invasive rodents cause extinctions and where rodenticides are considered too risky for larger inhabited places, and where only about 15 per cent of the world's islands can be restored with today's methods.²⁵ That setting carries four premises. The population must be closed, which a city's is not. The horizon must be decades, which no pest control customer has. The people living there must consent, which can be withdrawn: a mosquito project in Burkina Faso, holding authorisations from three regulators and village agreement, released about 16,000 modified males on 11 August 2025 and was ordered to halt on 22 August, its facilities sealed and samples destroyed.¹⁵¹¹¹⁴ And the release must be accepted as irreversible, which is why containment and island-specific targeting are designed in from the start.⁴

For a company doing structural work in a prairie city, this is not a technology on the horizon. It is a conservation tool built for a geography we do not have, on a timescale no customer would accept, requiring a permission no operator could obtain. The part worth carrying forward is the reasoning: that a method's premises travel with it, and that a control which cannot be stopped is a different kind of decision from one that can.

References

1. News report on the tCRISPR study, published by a science news aggregator in November 2022 and drawing on the research institution's release. News material summarising peer-reviewed work, flagged. Source for the modelling figure of about 250 modified mice eradicating an island population of 200,000 in around 20 years; the lead researcher's description of the approach as combining a naturally occurring gene drive with DNA editing to alter a fertility gene; his description of it as a humane approach without releasing toxins and his statement that the team is working on strategies to prevent failed eradication due to gene drive resistance; the statement that the broader project includes consideration of societal views and attitudes; and a collaborating agency scientist's statement that the prototype is designed to be highly specific for mice and is evidence that drives can be developed against other species. https://www.sciencedaily.com/releases/2022/11/221109124305.htm
2. Release on the same study published by a conservation organisation that is a consortium partner. Advocacy material from a participant, flagged. Source for the description of invasive mice as a significant cause of species extinctions globally and a particular threat to island ecosystems; the statement that hundreds of successful rodent eradications on islands are among the most impactful conservation actions available; and the statement that with methods available today it is feasible to restore only about 15 per cent of the world's islands. https://www.islandconservation.org/island-communities-threatened-by-invasive-rodents-have-potential-new-tool-to-consider-for-conservation-toolbox/
3. Leveraging a natural murine meiotic drive to suppress invasive populations, published in a national academy journal in 2022 and read as its abstract and significance statement. Peer-reviewed material. Source for the opening statement that invasive rodents are a major cause of environmental damage and biodiversity loss, particularly on islands; the proposal that the t haplotype's transmission bias could be leveraged for suppression or eradication on islands; the description of tCRISPR as progressively depleting fertile females through a CRISPR transgene embedded in the t haplotype targeting a haplosufficient female fertility gene; the use of spatially explicit individual-based in silico modelling on a hypothetical island showing eradication potential across a range of realistic scenarios; the engineering and testing of tCRISPR in a genetically contained split drive format with Cas9 and guide RNA on different chromosomes; and the note that earlier modelling suggested non-lethal t haplotypes could cause eradication in small populations through male sterility. https://www.pnas.org/doi/10.1073/pnas.2213308119
4. News article on the same study, published by a science news magazine in December 2022. News material, flagged. Source for the figures of 256 modified mice driving the modelled population to zero in around 25 years and the ordinary t haplotype doing so in about 43 years; the report that altered mice passed on the new genetics 95 per cent of the time; an outside researcher's description of the approach as clever for using CRISPR to damage fertility genes rather than to spread the construct; the lead researcher's suggestion that a final version might target mutations occurring only on one island so an escaped mouse would have no effect on mainland mice; his intention to consult people living in the area; and his statements that 25 years is a long wait, that the team would love to see it work faster, and that it is a work in progress. https://www.sciencenews.org/article/natural-gene-drive-invasive-rodents-extinction-island
5. Article on CRISPR gene drives tested in mammals, published by a science magazine. News material, flagged. Source for the description of a consortium member's team working with the t haplotype to create daughterless mice in which females carrying two copies give birth only to males, and for a conservation organisation director's statement that rodent pesticides which have eliminated mice and rats on small islands are too risky to use on larger islands with complex ecosystems and large human populations. https://www.scientificamerican.com/article/controversial-crispr-gene-drives-tested-in-mammals-for-the-first-time/
6. Super-Mendelian inheritance mediated by CRISPR-Cas9 in the female mouse germline, published in a general science journal in 2019 and read as its abstract. Peer-reviewed material. Source for the definition of a gene drive as biasing transmission of one of the two copies of a gene so it is inherited more frequently than by random segregation; the note that highly efficient systems had been developed in insects using targeted cleavage and homology-directed repair to convert heterozygous genotypes to homozygosity; and the description of the experiment using a guide RNA element embedded in the mouse tyrosinase gene. https://www.nature.com/articles/s41586-019-0875-2
7. The same 2019 study as summarised in an astrophysics data system abstract record. Abstract record of peer-reviewed material. Source for the finding that although Cas9 efficiently induced double-stranded breaks in the early embryo and male germline these were not corrected by homology-directed repair, while in the female germline they were, copying the element to the receiver chromosome and increasing its rate of inheritance. https://ui.adsabs.harvard.edu/abs/2019Natur.566..105G/abstract
8. Meiotic Cas9 expression mediates gene conversion in the male and female mouse germline, published in an open-access biology journal. Peer-reviewed material. Source for its description of the earlier CopyCat work and for the average gene conversion rate of 72 per cent in the female germline, and for the note that similar systems have been proposed as gene drives in wild rodents to limit infectious disease or reduce invasive populations in island ecosystems. https://journals.plos.org/plosbiology/article?id=10.1371%2Fjournal.pbio.3001478
9. Gene drives for vertebrate pest control: realistic spatial modelling of eradication probabilities and times for island mouse populations, published in a molecular ecology journal and read as its abstract. Peer-reviewed material. Source for the statement that CRISPR-based gene drives can theoretically spread through populations despite imparting a fitness cost; the modelling of homing and X chromosome shredding drives for eradicating island mice; the finding that both could be used against large populations; the exploration of the interactive effect of drive efficiency and the spatial ecology of the target population; and the consideration of polyandrous mating and sperm competition as possible compromises to efficacy. https://pubmed.ncbi.nlm.nih.gov/35073448/
10. Modelling CRISPR gene drives for suppression of invasive rodents using a supervised machine learning framework, read through a public biomedical archive. Peer-reviewed material. Source for the modelling of an island population with three suppression drive systems and the finding that for one drive 84 per cent efficiency produced complete suppression in 2 per cent of simulations, rising to 100 per cent of simulations at 87 per cent efficiency. https://pmc.ncbi.nlm.nih.gov/articles/PMC8716047/
11. Statement on the suspension of activities in Burkina Faso, published by the malaria project in August 2025. Material published by the affected project, flagged. Source for the authorisations granted in July 2025 by the national biosafety agency and the national environmental assessment agency, the health research ethics committee's approval and community agreement; the small-scale release of non gene drive genetically modified male bias mosquitoes on 11 August 2025 in accord with permit terms; the request by national authorities on 18 August to suspend all activities; and the team's statement that it had operated in compliance with national law since 2012. https://targetmalaria.org/latest/news/target-malaria-activities-suspended-in-burkina-faso/
12. News report on the halt, published by a general science journal's news service in September 2025. News material, flagged. Source for the report that the government suspended all the project's activities indefinitely, that researchers killed the mosquitoes still living in their insectary and the government sent a team to spray insecticide in the village to kill those released; the account of researchers being treated as though their laboratories were crime scenes according to meeting minutes; and the global principal investigator's statement that the team was waiting to find out what was going on and trying to find the rationale. https://www.science.org/content/article/after-humiliating-raid-burkina-faso-halts-gene-drive-project-fight-malaria
13. News report on the consequences of the suspension, published by a journal's regional news service in September 2025. News material, flagged. Source for the statement that the suspension disrupted plans by scientists in Uganda working on their own modified mosquitoes, that the project was put on hold in August, and that facilities were sealed and samples ordered destroyed. https://www.nature.com/articles/d44148-025-00286-z
14. News agency report on the termination, published in August 2025. News material, flagged. Source for the ministry's statement that all the project's activities had been halted across the national territory, that facilities containing genetically modified mosquitoes had been sealed since 18 August 2025, and that remaining samples would be destroyed under a prescribed protocol. https://apanews.net/burkina-faso-ends-flagship-malaria-project/
15. Explanatory news article on the halt, published in 2026. News material, flagged. Source for the release of around 16,000 genetically modified male mosquitoes in a village in the country's western region on 11 August 2025, described as the first field release of its kind on the African continent; the approval by three regulators in July 2025; the project's description of the release as small-scale relative to the wild population and as measuring survival, dispersal and mating competition rather than malaria cases; and the Uganda principal investigator's description of the reversal as surprising given that all regulatory approvals had been obtained. https://innovationreport.net/article/can-genetically-modified-mosquitoes-actually-stop-malaria-and-why-did-a-government-just-shut-the-trial-down/
16. Report on the halt published by a non-governmental organisation that campaigns on seeds and biotechnology. Advocacy material, flagged. Source for the statement that the project had begun its second field trial with genetically modified mosquitoes aiming to gain knowledge and experience before moving toward release of mosquitoes with gene drives at a later stage, and for the dates of the ministry's announcement and the sealing of facilities. https://www.saveourseeds.org/news/burkina-faso-halts-target-malaria-project/
17. Opinion article on the halt published by an online news and opinion site in February 2026. Advocacy material opposing open-field releases, flagged. Source for its characterisation of the halt as a victory for opponents, its report that about 75,000 mosquitoes were released on 11 August 2025, which differs from other accounts, and its assertions of local opposition and of scientific papers highlighting technical problems. https://countercurrents.org/2026/02/target-malaria-project-halted-in-burkina-faso-victory-for-opponents-of-open-field-gene-drive-releases/
18. Summary of the suspension published in a biotechnology industry newsletter in September 2025. Trade material from an organisation promoting agricultural biotechnology, flagged. Source for its account of the release of 16,000 genetically modified male mosquitoes on 11 August 2025, the July 2025 authorisations, the 18 August suspension request and the 22 August ministry announcement. https://www.isaaa.org/kc/cropbiotechupdate/article/default.asp?ID=21511
19. Overview of the New Substances Notification Regulations (Organisms), published by the federal environment department. Official government material. Source for the statement that the regulations were created under the authority of the federal environmental protection act and ensure new living organisms produced through biotechnology are assessed before introduction into Canada; that any person planning to manufacture or import a new living organism must notify the department, with manufacturing including producing, growing or developing; and that the department and the health department conduct a joint assessment determining potential risk to the environment, biodiversity and human health. https://www.canada.ca/en/environment-climate-change/services/managing-pollution/evaluating-new-substances/biotechnology-living-organisms/overview-regulations.html
20. Fact sheet on risk assessment of living organisms under the same act and regulations, published by the federal government. Official government material. Source for the statement that living organisms are defined as animate products of biotechnology and include higher organisms such as fish, insects and livestock animals, whether genetically modified or unmodified; that requirements apply to organisms not on the domestic substances list unless regulated under a listed act such as the Pest Control Products Act; and that the assessment covers risks to human health, the environment and biological diversity. https://www.canada.ca/en/environment-climate-change/services/managing-pollution/evaluating-new-substances/biotechnology-living-organisms/fact-sheet-organism-risk-assessments.html
21. Page on consultations on certain living organisms new to Canada, published by the federal environment department. Official government material. Source for the statement that legislation receiving royal assent in June 2023 amended the federal environmental protection act to introduce new obligations concerning living organisms new to Canada, and that consultation is now mandatory when the programme assesses a vertebrate animal or a prescribed living organism before the end of the assessment period. https://www.canada.ca/en/environment-climate-change/services/managing-pollution/evaluating-new-substances/voluntary-public-engagement-initiative.html
22. Commentary on the 2019 mouse study published by a preprint highlighting service. Commentary material, flagged. Source for the description of the CopyCat element as carrying a guide RNA targeting tyrosinase and a fluorescent marker knocked into an exon and disrupting the gene, with conversion visible as coat colour; and for the illustration that modelling three independent alleles requires 146 offspring for a 90 per cent chance of one animal with the wanted genotype. https://prelights.biologists.com/highlights/super-mendelian-inheritance-mediated-crisprcas9-female-mouse-germline/
23. Preprint version of the 2019 mouse study, posted to a biology preprint server in 2018. Preprint material, not peer reviewed at the time of posting, flagged. Source for the authors' statement that the results contribute data to the ongoing debate about applications to combat invasive rodent populations in island communities. https://www.biorxiv.org/content/10.1101/362558v2
24. Blog post on the tCRISPR result written by the consortium's programme coordinator. Advocacy material from a participant, flagged. Source for the description of the technology as leveraging a naturally occurring gene drive to spread faulty copies of a female fertility gene, and as a complementary tool to help address the issue of invasive mice. https://genedrivenetwork.org/blog/a-new-gene-drive-tool-could-help-solve-the-challenge-of-invasive-mice/
25. Companion document on the proposed approach to modernising the New Substances Notification Regulations (Organisms), published by the federal health and environment departments for stakeholder engagement in 2024. Official government material. Source for the statement that the government announced a commitment to strengthen the environmental protection act in April 2021 and began a complete review of the regulations, with objectives including enhanced protection of human health, the environment and biodiversity, and strengthened openness of regulatory oversight for living organisms. https://www.canada.ca/en/environment-climate-change/services/managing-pollution/evaluating-new-substances/biotechnology-living-organisms/overview-regulations/proposed-approach.html