In 2018, Oxitec’s proposal to test the release of biologically modified mosquitoes to combat biting invasive populations was bandied back and forth between the Environmental Protection Agency and Food and Drug Administration. The proposal drew much comment, plus there was a presidential election, and new department heads appointed. In the midst of all that turmoil, Oxitec — a U.S.-owned, U.K.-based company that develops biologically engineered solutions to control disease-transmitting insects — withdrew its application.
Not because it thinks it doesn’t have promise, but because Oxitec says it has something better to offer. The EPA’s public comment on its 2nd Generation trial opened on the federal register on Sept. 11. (Visit federalregister.gov and search for “Oxitec.”)
“The 2nd Generation mosquito is just as environmentally friendly and safe, but with the potential for greater performance and overall cost effectiveness,” said Kelly Matzen, who heads research and development for Oxitec.
Here are the key points.
- Only males
The eggs of the 2nd Generation mosquito produce ONLY males. Male mosquitoes don’t bite and are therefore incapable of spreading diseases such as dengue, Zika, chikungunya and yellow fever. According to Oxitec, its Aedes aegypti carry a self-limiting gene that prevents female offspring from surviving, allowing for male-only production. The previous proposed method required adult mosquitoes to be carefully sorted by gender.
- Eggs, not adults
Instead of raising modified mosquitoes to adulthood before releasing them into the wild, the 2nd Generation mosquitoes can be distributed as eggs in boxes. (The eggs are currently produced in the U.K. and shipped globally to places such as Brazil where a trial is underway.) A box containing eggs could be placed in a back yard 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. The previous proposed method required adult mosquitoes to be raised near the test site and then released via the use of a specially equipped van.
- Still self-limiting, but better
With the 1st Generation of the Oxitec mosquito, released males mated with a female in the wild, and all of the offspring — male and female — would die. With the 2nd Generation, it just targets the females. 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.
- Tetracycline
And, finally, Oxitec said the 2nd Generation mosquitoes it plans to release do not come into contact with tetracycline at any stage, either as eggs or as adults.
The 2nd Generation mosquito has many advantages, said Kevin Gorman, who heads Oxitec’s field operations.
“It’s easier to use and a way to get the tools to fight Aedes aegypti into the hands of many,” he said.
Phil Goodman is the chairman of the board of the Florida Keys Mosquito Control District. He’s said the 2nd Generation technology overcomes many hurdles its predecessor didn’t including, potentially, the cost.
“The EPA doesn’t allow any talk of commercialization during the comment period,” Goodman said, “so we don’t have any projections. But if we can shorten the route to production and make it simpler, that has to have an impact on the cost down the road. I mean, if Oxitec ships eggs instead of adult mosquitoes … well, they could probably fit one million genetically modified mosquitoes in something the size of a shoebox. This could make distribution a lot more effective.”
The EPA has announced a 30-day public consultation, during which residents in the Florida Keys and elsewhere can share their views on the project with the EPA.
Should approval be granted, locations for the trials in the Keys would be a joint decision between Oxitec and the Florida Keys Mosquito Control District. This is of particular relevance since the Key Haven neighborhood rejected a genetically modified mosquito release in its neighborhood in a non-binding referendum question in the 2016 general election. Precinct 11 voted 65% against the study. But in a second referendum question, for the entire county, 31 of 33 precincts approved an “effectiveness trial in Monroe County” of genetically modified mosquitoes. In Ocean Reef, 84% of voters approved of a test and in Grassy Key, 72% of voters approved of a test.
Oxitec’s 1st Generation mosquito proposal met with public resistance in the Keys. Dr. John W. Norris of Key West has opposed the technology, citing the possible creation of an antibiotic-resistant scenario that could pose a health threat to humans. Proponents of the technology welcome a way to fight vector diseases (transmitted through the bite of infected insects) such as dengue, Zika, yellow fever and chikungunya. Local veterinarian Dr. Doug Mader said he supported the 1st Generation technology 100%, as it would have reduced the number of canine heartworm infections — he said he sees four or five a month in the Keys — also a mosquito-borne disease.
Oxitec reports it has positive regulatory findings from independent scientific reviews and regulators from around the world. Their mosquitoes have been determined by multiple regulatory agencies, including the U.S. FDA and Brazil’s CTNBio, to be safe, and to pose no threat to humans, animals or the environment.
