Oxitec’s GM mosquitoes starting to show impact

Oxitec's Heidi Groves releases genetically modified mosquitoes in West Bay recently. - Photo: Charles Duncan

Researchers studying the release of genetically modified mosquitoes in West Bay say they are starting to see the gene show up in mosquito larvae, meaning those mosquitoes likely will not survive to adulthood.

Oxitec, the British company that developed the GM mosquitoes, and Cayman’s Mosquito Research and Control Unit began releasing hundreds of thousands of male GM mosquitoes in a small section of West Bay in July. The idea is that the GM males will mate with local females and pass on a gene that prevents the next generation from surviving to adulthood.

Read more on the Compass Zika page

The GM mosquito project targets Aedes aegypti, the species responsible for carrying Zika, dengue, chikungunya and yellow fever.

Oxitec Operations Manager Renaud Lacroix said his team is starting to find mosquito larvae in the test area with the gene marker, meaning the GM mosquitoes are starting to mate with the local population. He estimates that about 10 percent of the local female mosquitoes have mated with Oxitec’s males at this point.

“It takes a few months for the reductions to be visible,” he said, because “it takes time to build up the numbers.”

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He said the results his team is seeing now are on track with previous research. Mr. Lacroix explained that the male GM mosquitoes take time to replace the wild population. Oxitec researchers are releasing about 400,000 modified mosquitoes each week in the 300-acre test zone.

As the releases continue, researchers expect to see more and more females mating with the GM males and, in turn, fewer Aedes aegypti surviving to adulthood and fewer wild males to mate with.

MRCU Director Bill Petrie said that despite the political opposition to the project over the summer, he has heard from a number of people recently about pushing up the schedule to release the GM mosquitoes in George Town given the growing number of Zika cases there. He said the GM mosquitoes are not meant to be a quick response to a disease outbreak; the Oxitec project is a long-term preventive measure.

Mr. Lacroix said Oxitec’s mosquito release program is meant to work alongside other efforts, such as traditional spraying, to deal with mosquito-borne disease.

Oxitec has permission to work only in the defined test area in West Bay. Depending on those tests, Oxitec and the MRCU hope to be able to treat more areas in Cayman with the GM mosquitoes. But the MRCU and Oxitec will need to go back to the National Conservation Council for permission, and still need to figure out plans for funding.

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