First GMO Mosquitoes to Be Released in the Florida Keys

This Spring, the biotechnology company Oxitec plans to release genetically modified (GM) mosquitoes in the Florida Keys. Oxitec says its technology will combat dengue fever, a potentially life-threatening disease, and other mosquito-borne viruses — such as Zika — mainly transmitted by the Aedes aegypti mosquito.

While there have been more than 7,300 dengue cases reported in the United States between 2010 and 2020, a majority are contracted in Asia and the Caribbean, according to the U.S. Centers for Disease Control and Prevention. In Florida, however, there were 41 travel-related cases in 2020, compared with 71 cases that were transmitted locally.

Native mosquitoes in Florida are increasingly resistant to the most common form of control — insecticide — and scientists say they need new and better techniques to control the insects and the diseases they carry. “There aren’t any other tools that we have. Mosquito nets don’t work. Vaccines are under development but need to be fully efficacious,” says Michael Bonsall, a mathematical biologist at the University of Oxford, who is not affiliated with Oxitec but has collaborated with the company in the past, and who worked with the World Health Organization to produce a GM mosquito-testing framework.

Bonsall and other scientists think a combination of approaches is essential to reducing the burden of diseases — and that, maybe, newer ideas like GM mosquitoes should be added to the mix. Oxitec’s mosquitoes, for instance, are genetically altered to pass what the company calls “self-limiting” genes to their offspring; when released GM males breed with wild female mosquitoes, the resulting generation does not survive into adulthood, reducing the overall population.

But Oxitec has been proposing to experimentally release GM mosquitos in the Keys since 2011, and the plan has long been met with suspicion among locals and debate among scientists. Some locals say they fear being guinea pigs. Critics say they are concerned about the possible effects GM mosquitoes could have on human health and the environment. In 2012, the Key West City Commission objected to Oxitec’s plan; in a non-binding referendum four years later, residents of Key Haven — where the mosquitoes would have been released — rejected it, while residents in the surrounding county voted in support of the release. With the decision left up to the Florida Keys Mosquito Control District, officials approved the trial to be conducted elsewhere in the Keys.

According to Oxitec, the release was delayed due to a transfer of jurisdiction over the project from the U.S. Food and Drug Administration to the Environmental Protection Agency.

The company reapplied for approval to release a new version of the mosquitoes, called OX5034, in the Keys. In May, the EPA granted a two-year experimental use permit, which the agency can cancel at any time. State and local sign-off soon followed — finally giving the project the greenlight.

Oxitec has been proposing to experimentally release GM mosquitos in the Keys since 2011, and the plan has long been met with suspicion.

Oxitec’s OX5034 mosquitoes are the first GM mosquitoes approved for release in the U.S. The company has already conducted a trial with the OX5034 mosquitoes in Brazil and released more than a billion of a previous version, called OX513A, there and in other locations over the years — including the Cayman Islands. The company says it is confident in the effectiveness and safety of the technology.

But some scientists want to hit pause on Oxitec’s Florida trial, to find what they say is a fairer process in deciding to release the mosquitoes. Others want to see clearer proof that this technology is even necessary, claiming that the company has only released its most positive data with the public and has kept other key data, including whether the mosquitoes curb disease transmission, private. And if the release actually launches as planned, some Keys residents say they aim to interfere.

Critics also say that Oxitec failed to engage with local communities in Florida and get their consent to release the mosquitoes. “What’s the most upsetting is that the very people that are going to be most impacted, both by the benefits or the risks of such a decision, have like the smallest voice in how these choices are made. I think that’s a really big issue,” says Natalie Kofler, a molecular biologist and bioethicist who founded Editing Nature, a platform that advocates “for inclusive decision-making processes to steer” the use of genetic technology. “If Oxitec doesn’t do this right,” she adds, “we could have huge impact on delaying the use of other beneficial technologies like that in the future.”

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