Bloomberg Law
May 1, 2020, 10:20 PM

EPA Grants First Permit to Test Genetically Modified Mosquitoes

Adam Allington
Adam Allington

The EPA on Friday granted permission for genetically engineered mosquitoes to be released into the Florida Keys and around Houston to see if they can help limit the spread of mosquito-borne illnesses.

British biotech company Oxitec Ltd was granted an experimental use permit to release a genetically engineered type of the mosquito species Aedes aegypti, which is a known vector of Zika virus and viruses that cause yellow fever and dengue fever, the Environmental Protection Agency office of Chemical Safety and Pollution announced.

Oxitec must get state and local approval before it can start field testing. But if granted, testing will take place over a two-year period in Monroe County, Fla., starting this summer, and in Harris County, Texas, beginning in 2021.

Oxitec says its “2nd Generation Friendly” Aedes aegypti carries a gene that prevents female offspring from surviving, allowing for male-only production.

When genetically engineered males are released into the field, they mate with wild female mosquitoes. With only male mosquitoes able to survive, the population decreases as the gene spreads, the company says.

‘Establishment of Hybrid Mosquitoes’

Oxitec’s first field trial in Brazil achieved up to a 96% suppression of target disease transmitting mosquito populations in dense urban settings, the company said.

But in public comments on the permit approval docket, Jaydee Hanson, policy director at the Washington, D.C.-based Center for Food Safety, questioned Oxitec’s claims and warned of other possible dangers.

“Most (but not all) of the GE mosquitoes’ offspring die at the late larval stage, in the water where the female mosquitoes lay their eggs,” Hanson wrote.

“This partial survival rate, even if low (a reported 3 to 4% in laboratory conditions), would lead to the establishment of hybrid mosquitoes in the environment, which might possess altered properties, including the potential for enhanced disease transmission or resistance to insecticides,” Hanson said.

Monroe County, Fla., with a population of about 75,000, includes the Florida Keys and mostly uninhabited areas of the Florida Everglades. But Harris County, Texas, which includes the city of Houston, is among the country’s most populous counties, with more than 4 million people.

“EPA looks forward to receiving field test results regarding the effectiveness of this promising new tool that could help combat the spread of mosquito-borne diseases like the Zika virus,” the agency said in a statement.

EPA’s decision and the approved permit are available in in Docket ID EPA-HQ-OPP-2019-0274.

To contact the reporter on this story: Adam Allington in Washington at

To contact the editor responsible for this story: Gregory Henderson at