Screwworm Tipped as First Gene Drive Extinction Target
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- Kevin Esvelt at MIT, creator of the first CRISPR-based gene drive, is betting the New World screwworm (Cochliomyia hominivorax) — not the malaria mosquito — will be the first species targeted for an extinction gene drive, because the Americas are more receptive to genetic engineering than African nations like Burkina Faso, where a mosquito gene-drive project was raided and shut down last year.
- Screwworm flies lay eggs in the wounds of mammals and birds; the larvae burrow into living flesh and can kill the host, and the pest remains a major problem for South American livestock despite being wiped out of North and Central America in the 1960s.
- The 1960s sterile-insect technique that eliminated screwworms from North America — releasing radiation-sterilized males so females mate only once and produce no offspring — is too expensive to deploy across South America, a gap gene drives could fill because they spread themselves rather than requiring mass releases.
- INIA in Uruguay (led by Alejo Menchaca) and DARPA's GUARDIAN program are both developing screwworm gene drives, though neither program disclosed its progress; the article notes working gene drives already exist in mosquitoes, making screwworm development "almost certainly possible" with sufficient effort.
- Colossal Biosciences, the de-extinction company, recently proposed its own screwworm gene drive, but Esvelt said the company "has no experience with gene drives whatsoever in any way, shape, or form, or with working with insects in any way, shape, or form."
- Resistance to gene drives is expected but can be countered by releasing multiple drive variants, and Esvelt argues the ecosystem-risk objection is weak because screwworms were already eliminated from North America with no obvious harm — and frozen stocks could be kept as insurance.
Why it matters: If screwworm gene drives work, the technology gets a real-world test bed for wiping out a pest Americans have already proven they can regionally eliminate, opening the door to later deployment against malaria and dengue vectors — the very applications the article says are currently blocked by anti-GMO opposition in countries like Burkina Faso.
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