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By Lisa M. Campbell, Timothy D. Backstrom and Barbara A. Christianson

On May 1, 2020, the U.S. Environmental Protection Agency granted an experimental use permit (EUP) to Oxitec Ltd. (Oxitec) to field test the use of genetically engineered Aedes aegypti mosquitoes as a way to reduce populations that serve as a vector for a variety of diseases including Zika virus.  The EUP is designed to test the effectiveness of genetically engineered Aedes aegypti mosquitoes as a way to reduce mosquito populations in specific locations with monitoring and sampling of the resultant mosquito populations.  These field tests will proceed only after state and local approval, and they are intended as a first step toward potential wider use of genetically modified mosquitoes in the U.S.

Oxitec’s field tests will be conducted, if approved by state and local authorities, over a two-year period in Monroe County, Florida, beginning in summer 2020, and in Harris County, Texas, beginning in 2021.  During these field tests, Oxitec will release into the environment male mosquitoes that have been genetically modified to carry a protein that will inhibit the survival of female offspring.  After males carrying this protein mate with wild female mosquitoes, it is anticipated that only the male offspring will survive to become fully functional adults and that these male offspring will retain the same genetic modification.  This should provide multi-generational effectiveness in reducing the number of adult females in Aedes aegypti mosquito populations in the release areas.

Female mosquitoes are the ones who bite humans and that serve as the vector for blood-borne illnesses.  Since only male mosquitoes will be released into the environment and their female offspring are not expected to survive, EPA does not believe they will pose a health risk to the human population.  EPA anticipates that these modified mosquitoes could be an effective tool in combatting the spread of certain diseases like the Zika virus in light of the growing resistance of mosquito populations to current insecticides.  It is also anticipated that there will be no adverse effects to animals such as bats and fish who consume the genetically modified mosquitoes.

Oxitec is required to monitor and sample the mosquito population weekly in the treatment areas to determine how well the product works for mosquito control and to confirm that the modified genetic traits disappear from the male Aedes aegypti mosquito population over time.  EPA has also maintained the right to cancel the EUP at any point during the 24-month period if unforeseen outcomes occur.

EPA’s decision and the approved permit are available here.