Millions of genetically modified mosquitoes could be released in the Florida Keys this spring if British researchers win approval to use the bugs against two viral diseases. Never before have insects with modified DNA come so close to being set loose in a residential U.S. neighborhood.
“This is essentially using a mosquito as a drug to cure disease,” said Michael Doyle, executive director of the Florida Keys Mosquito Control District, which is waiting to hear if the federal Food and Drug Administration will allow the experiment.
Dengue and the chikungunya virus are growing threats in the U.S., but some people are more frightened at the thought of being bitten by a genetically modified organism. As of Sunday, nearly 140,000 people had signed a Change.org petition against the experiment.
Even potential boosters said those responsible must do more to show that benefits outweigh the risks of breeding modified insects that could bite people.
“I think the science is fine, they definitely can kill mosquitoes, but the GMO issue still sticks as something of a thorny issue for the general public,” said Phil Lounibos, who studies mosquito control at the Florida Medical Entomology Laboratory.
Mosquito controllers said they’re running out of options. With climate change and globalization spreading tropical diseases farther from the equator, storm winds, cargo ships and humans carry these viruses to places like Key West, the southernmost U.S. city.
Insecticides are sprayed year-round in the Keys’ crowded neighborhoods. But the mosquitoes known as Aedes aegypti, whose biting females spread these diseases, have evolved to resist four of the six insecticides used to kill them.
Enter Oxitec, a British biotech firm. It patented a method of breeding mosquitoes with pieces of genes from coral, cabbage, E. coli bacteria and the herpes simplex virus. This synthetic DNA kills mosquito larvae but is thought to pose no significant risks to other animals.
Oxitec’s plan works like this: Lab workers manually remove the modified females, so they can release only modified males, which don’t bite for blood like the females do. The modified mosquito males then mate with natural female mosquitoes in the wild, and their offspring die, reducing the population of the disease-spreading Aedes aegypti.
Company spokeswoman Chris Creese said Oxitec plans a test similar to its 2012 experiment in the Cayman Islands, where 3.3 million modified mosquitoes were released over six months, suppressing 96% of the targeted bugs.
Critics accused Oxitec of failing to obtain informed consent in the Caymans, saying residents weren’t told they could be bitten by a few stray females. Instead, Oxitec said only non-biting males would be released, and that even if humans were bitten, no genetically modified DNA would enter their bloodstream. Neither claim is entirely true, outside observers said.
“I’m on their side, in that consequences are highly unlikely. But to say that there’s no genetically modified DNA that might get into a human, that’s kind of a gray matter,” Lounibos said.
Creese says Oxitec has now released 70 million of its mosquitoes in several countries and received no reports of human impacts caused by bites or from the synthetic DNA, despite regulatory oversight that encourages people to report any problems. “We are confident of the safety of our mosquito, as there’s no mechanism for any adverse effect on human health.”
FDA spokeswoman Theresa Eisenman said there won’t be any field tests until the FDA has “thoroughly reviewed” information.
Key West resident Marilyn Smith wasn’t persuaded. Neither disease has had a major outbreak in Florida, she said, so “why are we being used as the experiment, the guinea pigs — just to see what happens?”