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Everything you need to know about the zika virus in South Florida.

FDA Mulls Genetically Modified Mosquitoes In Key Haven


The Food and Drug Administration (FDA) has extended the public comment period to May 13 on a proposed field trial in the Florida Keys. The trial involves the release of a thousand genetically modified mosquitoes.

It would be the first such trial in the U.S. by Oxitec, a British company that genetically alters the males in the Aedes aegyptispecies. The modification causes the offspring of these males to die quickly.

“What we've done is develop the self-limiting mosquito,” says Oxitec CEO Hadyn Parry. “We release males because males don't bite or spread disease. Every mosquito that has ever bitten you has been a female. The male goes out, looks for a female and mates with her, and when that happens all those offspring will die. A female can produce up to 500 eggs in her lifetime, but all those eggs will die if the male was an Oxitec male.”

The modified males carry a gene that causes their offspring to die and another gene that gives their offspring a red color that can't be seen by the naked eye. Oxitec checks mosquito larvae in little traps to see how many are red. For example, if 40 percent of the larvae are red, that means 40 percent of the mosquitoes have been fathered by an Oxitec mosquito. 

Parry says Oxitec has reduced the population of this mosquito species by more than 90 percent within about six months in targeted areas overseas. Now, the company wants to conduct a field trial in the small community of Key Haven.


“We tend to release the mosquitoes early, 6 o'clock in the morning or even earlier. If you're standing in the street, what you’ll see is a van coming along,and you'll see like a little puff coming outside of the van. We release the mosquitoes from little pots,” Parry says. “First of all, they’ll go and find a little bit of shade, sit there and rest for a bit, and then they’ll go off and look for females. So they actually disperse very rapidly.”

Credit Oxitec
Oxitec male mosquitoes are released from a pot in Jacobina, Brazil.

After an outbreak of dengue fever in the Keys, the Florida Keys Mosquito Control District began talks with Oxitec five years ago about how to deal with the invasive Aedesaegypti mosquito, which spreads diseases like dengue fever, chikungunya and Zika. Efforts like spraying insecticide have only been moderately successful.

But the proposed trial in Key Haven is opposed by critics who say there’s no disease outbreak in the area right now. "We don't have dengue. We don't have chikungunya. We have no Zika," Keys businesswoman Mila de Mier told NPR. "Mosquito control is doing a really good job here. We don't see the need to jump into this." De Mier’s petition on Change.org opposing use of “the Florida Keys as a testing ground for these mutant bugs” has more than 160,000 signatures.

Opponents are also concerned about the possibility of being bitten by a genetically modified female. Parry says a few females will inevitably wind up being modified and released with the males.“But if you are bitten by a GM mosquito, it's exactly the same as a wild one,” Parry says. “The time to do this is when you don’t have a problem.”

The FDA has issued a preliminary finding that the trial would pose no significant environmental impact based on five years worth of data provided by Oxitec. “In their opinion, there is no negative impact on human health or the environment,” Parry says. “The World Health Organization has also recommended our product, so that wouldn't happen if there were any concerns over health or safety. What I think is the major concern in the Keys to be honest is - if you do a trial, does that mean you have disease? So, actually it's a tourism question.”

Oxitec is holding evening meetings on Monday and Tuesday (4/11-4/12) at the Key West Marriott Beachside Hotel to answer questions about the proposed Key Haven trial. If the FDA gives its approval, the Florida Keys Mosquito Control Board will have the final say.



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