Feds approve Oxitec mosquito trial

State approval needed before field tests begin

The federal Environmental Protection Agency has approved field tests for Oxitec’s biologically modified mosquitoes. If approved by the state of Florida and local authorities, the first tests will take place in the Florida Keys beginning in summer 2020 and in Texas beginning in 2021.

For the trials to take place in the Keys — the use of biologically-modified male mosquitoes to control the Aedes aegypti mosquito — the Florida Department of Agriculture and Consumer Services must sign off. The Aedes aegypti mosquito is responsible for transmitting Dengue, Zika, chikungunya and yellow fever.

Oxitec is a U.S.-owned, U.K.-based company that develops biologically engineered solutions to insect control issues. Oxitec revealed its “2nd Generation” mosquito technology in September 2019. In both the first and second versions of the technology, Oxitec takes a biologically modified mosquito and uses tetracycline to keep it alive to adulthood so that it can mate. A very basic layman’s explanation of the procedure is that when the tetracycline applications stop (when the mosquitoes are released into the wild), the mosquitoes and offspring die. In the 2nd Generation technology, only female breeders are treated with tetracycline in the lab in the U.K. 

The 2nd Generation mosquitoes can be distributed as eggs in boxes and shipped globally. A box containing eggs could be placed in a backyard and filled with water, after which the males hatch and start to grow. When the mosquitoes emerge, they fly away into the neighborhood to find female mosquitoes to mate with. Male progeny survive, also carrying the self-limiting gene to half its offspring that are male only … and so on. The 2nd Generation technology allows Oxitec to reduce the number of times the egg box must be refilled, reduces the total population, and Oxitec says, when releases stop, the 2nd Generation mosquito dies out in the wild after a few generations.

Dr. John W. Norris III, the chief of staff of the Lower Keys Medical Center in Key West, led the charge in 2018 to stop the Oxitec approval from EPA and even visited Washington, D.C. to meet with regulators personally. In the past, he has said his concerns have nothing to do with genetic modification, but about spreading antibiotic resistance and the ability to treat “superbugs” with one of the strongest, most versatile antibiotics on the market — tetracycline. 

Oxitec says that the eggs and the adult male mosquitoes that hatch from them are not exposed to tetracycline. Dr. Norris said, “The act of giving birth — whether it’s a mosquito mother or human mother — is a very germy, gooey thing,” he said. Or, more scientifically, “… breeding females should be heavily weighted for tetracycline resistant bacteria … you must challenge the microbiome transfer from mother to child …”

Tetracycline is a common genetic tool switch used in many scientific experiments, most of them in the lab. However, tetracycline is also widely used in agricultural applications in Florida.

When and if the trials begin in Florida, Oxitec is required to monitor and sample the treatment areas to determine if it works and to confirm the genetic traits from the modified mosquito disappear over time. The EPA has maintained the right to cancel the Experimental Use Permit at any point during a 24-month period if unforeseen outcomes appear. 

Sara Matthis
Sara Matthis
Sara Matthis thinks community journalism is important, but not serious; likes weird and wonderful children (she has two); and occasionally tortures herself with sprint-distance triathlons, but only if she has a good chance of beating her sister.

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