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Billions Of Genetically Engineered Mosquitoes Permitted For Release in California And Florida


Tom Hale

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

Aedes aegypti.

The Aedes aegypti mosquito is a prominent vector for several human diseases including Dengue, chikungunya, Zika, yellow fever, and more. Image credit: frank60/

The US Environmental Protection Agency (EPA) has given the go-ahead for biotech company Oxitec to release billions of genetically engineered mosquitoes in Florida and California, with a mission to combat mosquito-borne diseases like Dengue fever and the Zika virus.

After passing a risk assessment, Oxitec's technology was given an experimental use permit allowing 2.4 billion gene-tweaked mosquitos – over 2 billion in California and just under 400 million in Florida –  to be released in two separate periods between 2022 to 2024. 


This recent permit comes off the back of a pilot project in the Florida Keys successfully carried out in 2021. Now the project has received the EPA permit, applications can be sent to local state regulators to mull over. 

The plan is to release billions of male Aedes aegypti mosquitoes, which don’t bite, genetically modified to express the protein tTAV-OX5034. The Aedes aegypti mosquito is not native to California or Florida, but it’s become a prominent vector for several human diseases including Dengue, chikungunya, Zika, and yellow fever. 

Once the introduced males mate with wild female mosquitoes, the protein will be passed on and effectively kill female offspring before they reach maturity, thereby reducing the local population of mosquitos and quashing disease transmission (at least in theory).

While the mosquitos and Oxitec’s technology have undergone dozens of tests and trials, not everyone likes the prospect of releasing swarms of genetically engineered bugs into the wild. Previous pilot trials have received some resistance from concerned locals, with some critics calling it a “Jurassic Park experiment.”


One source of controversy was a 2019 paper studying Oxitec’s genetically modified mosquitoes in Brazil, concluding that the project didn’t work as intended as many mosquitoes were surviving into adulthood and potentially deepening the area's mosquito problem. However, the journal’s editors then issued an Editorial Expression of Concern for the study, noting that a number of concerns had been raised with the research.

News of releasing the genetically modified mosquitoes in California is also causing some heads to turn. 

“Once released into the environment, genetically engineered mosquitoes cannot be recalled,” Dr Robert Gould, President of San Francisco Bay Physicians for Social Responsibility, said in a statement released by Friends of the Earth. “Rather than forge ahead with an unregulated open-air genetic experiment, we need precautionary action, transparent data and appropriate risk assessments.”

“This experiment is unnecessary and even dangerous, as there are no locally acquired cases of dengue, yellow fever, chikungunya or Zika in California,” added Jaydee Hanson, Policy Director for the International Center for Technology Assessment and Center for Food Safety


Oxitec has tried to quell these concerns from the public, maintaining that their mosquitos offer a safe and sustainable pest control technology that does not harm beneficial insects, such as bees and butterflies. Nevertheless, the controversy is unlikely to die down anytime soon. 

“Given the growing health threat this mosquito poses across the U.S., we’re working to make this technology available and accessible. These pilot programs, wherein we can demonstrate the technology’s effectiveness in different climate settings, will play an important role in doing so. We look forward to getting to work this year,” Grey Frandsen, CEO of Oxitec, said in a statement.


natureNaturenaturecreepy crawlies
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