GMO Mosquitoes Proposed Again For Keys — As New Study Finds They Can Interbreed With Wild Insects

This post was updated at at 12:15 p.m. on Sept. 12

The prospect of genetically modified mosquitoes is back for the Florida Keys — just as a new study raises concerns about the technology.

The British company Oxitec wants to make the Keys the first U.S. test of its genetically modified Aedes aegypti mosquito. That's the kind of mosquito that transmits diseases like Zika and dengue fever.

The genetically modified mosquitoes are bred to be sterile, so their offspring that mate with wild mosquitoes don't survive and the overall population plummets. And the company says it can produce only male mosquitoes, which don't bite people and thus spread disease.

The public has until Oct. 11 to comment on the application with the Environmental Protection Agency.

The proposal has been controversial in the Keys and even led to a nonbinding public vote in 2016. A majority of voters approved, as has the Florida Keys Mosquito Control District, although residents of Key Haven, the Lower Keys neighborhood first proposed as a trial site, rejected the idea.

This application is for Oxitec's second generation of genetically modified mosquitoes. The company says it has successfully tested this version in Brazil.

Local opponents are still concerned — especially after a report published this week on Nature.com found that first-generation Oxitec mosquitoes in Brazil have interbred with local mosquitoes.

Oxitec's mosquitoes were bred from wild mosquitoes from Cuba and Mexico, then released in the Brazilian town of Jacobina.

"The three populations forming the tri-hybrid population now in Jacobina (Cuba/Mexico/Brazil) are genetically quite distinct, very likely resulting in a more robust population than the pre-release population due to hybrid vigor," the study found.

Barry Wray, executive director of the Florida Keys Environmental Coalition, said his group would be asking for an extension on the comment period. He also said the new study confirms the suspicions of local opponents.

"It's another verification of the unquantified risk associated with these genetically modified mosquitoes," he said. "A new version based on the same lethal gene technology represents the same problems, with just a new marketing discussion wrapped around it."

Oxitec scientists are not concerned with the study — they're pleased with its results, said Kelly Matzen, the company's head of global operations.

She said the self-limiting genes that make the Oxitec mosquitoes suppress populations only survive for a few generations and that the hybrids remaining after that are all Aedes aegypti — which are all exotic in the New World and share the same background genetic make-up derived from the wild population in Africa.

"We're not talking about differences between species," she said. "We're talking about the same species with the same traits and the same genes."

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