Boxes containing the eggs of genetically modified Aedes aegypti mosquitoes, water and a little food are being placed in six locations in the Lower and Middle Keys this week — in a trial that will be the first of its kind in the United States.
The genetic modification is intended so that female offspring won't survive. Female mosquitoes are the ones that bite and can transmit diseases like dengue and zika.
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The genetically modified males are supposed to breed with wild females — and then their female offspring won't survive, either.
Andrea Leal is in charge of the Florida Keys Mosquito Control District. The district has been working with the British firm Oxitec for more than a decade, since a 2009-10 outbreak of dengue fever in Key West.
The Keys saw another dengue outbreak last year, in Key Largo.
"We're lucky that we have a robust budget and we do pretty much everything we possibly can that we can to control these mosquitoes but we're still seeing them in populations that are able to transmit diseases," Leal said.
The trial won approval from federal, state and local agencies. In a 2016 referendum, 58 percent of Keys voters approved holding a trial of genetically modified mosquitoes in the Keys. But opposition has continued throughout the process.
Dana Perls, with Friends of the Earth, says the modified mosquitoes haven't had enough review — and could have unintended consequences. Disease-carrying mosquitoes from a different species, like the "much more dangerous, much more aggressive and problematic mosquito" — Aedes albopictus — could move in to fill the gap, she said.
"Not only is it very unlikely to be effective, but it is likely to cause more harm than good," she said.
A total of about 144,000 of the genetically modified mosquitoes are set to be released over 12 weeks in the trial's first phase. Leal said results are unlikely to be reported before the end of the year, at the earliest.
