A biotech company must convince Florida Keys residents to approve the use of genetically altered mosquitoes for the first time in the U.S. to fight the Zika virus, which is spreading a few hours up the road in Miami.

But there is much angst and concern in the community over the use of genetically modified bugs and their impact on the environment.

The Food and Drug Administration decided on Friday to approve a clinical trial in the Keys to examine the effectiveness of sterilizing mosquitoes that spread the Zika virus, which can cause the birth defect microcephaly.

The company that created the mosquitoes, United Kingdom biotech firm Oxitec, needs to receive approval from local officials before a trial can begin. It faces a voter referendum in November.

The company makes genetically altered male Aedes aegypti mosquitoes, which are one of the two species that spreads the Zika virus through biting people. The males mate with females and impede breeding of the mosquitoes.

The local mosquito control board for Monroe County, which includes the Keys, called for the non-binding referendum to be held in November.

The board is not "not legally bound by the results but they are cognizant of the fact they want to get this out and get people's views," said Oxitec CEO Haydn Perry on a Friday call with reporters.

With the November vote looming, Parry said the company knows the community has concerns about introducing genetically altered mosquitoes into the environment.

"When you look at the broad sway of opinion we get strong support," he said. "We recognize there are a number of people who oppose this for various reasons."

Parry denied a report that the company is conducting robocalls to sway voters to approve the trial, but he said employees are knocking on people's doors.

"We just use humans," he said.

The company said it is not spending any money on a campaign and cannot under federal law since it is based overseas.

Oxitec said it has been meeting with residents in the Keys to listen to concerns, including holding town halls.

It is not clear how steep a mountain Oxitec has to climb in the Florida Keys. No public polling has been done, but opposition to Oxitec's trial has been rampant.

A petition on Change.org calling for the local board to nix the trial has gotten 168,752 signatures. However, it is not known how many of those supporters live in the Florida Keys.

The petition highlights fears of genetically modified organisms in food as part of the reason to halt the trial.

"Nearly all experiments with genetically modified crops have eventually resulted in unintended consequences: superweeds more resistant to herbicides, mutated and resistant insects also collateral damage to ecosystems," it reads.

A grassroots effort has tried for years to get labeling for GMOs in food due to questions about their safety, even though the FDA and other agencies have said they are safe. Vermont implemented a strict law last month that requires foods to have GMO labels.

Congress is considering a law that requires GMO labels but gives manufacturers the options of placing a barcode or website link for consumers.

The FDA received more than 2,600 comments on Oxitec's request to conduct the trial. Some of the commenters were from Florida, most notably the nonprofit Florida Keys Environmental Coalition.

The environmental group said Oxitec's conclusion that the environmental impact from the mosquitoes would be negligible is "likely affected by their bias to get a product to market as quickly as possible, instead of true concern with regard to the safety and effectively of this novel, unnecessary and risky approach."

Parry did concede that if the board decides against holding the trial in Key Haven, about a mile north of Key West, Oxitec could go elsewhere.

The trial would take up to nine months and would need further FDA approval to deploy mosquitoes in the U.S.

Oxitec already conducted trials in the Cayman Islands, Panama and parts of Brazil, which has been hit hard by the Zika virus. The mosquitoes have been approved in Brazil and are being used in a neighborhood in the city of Piracicaba.

The company says it can control about 90 percent of the mosquito population in the area, compared to 30-50 percent using traditional means such as insecticides.

"Florida Keys has been crying out for new tools [to fight mosquitoes] for the past six years," said Derric Nimmo, a senior scientist with Oxitec who would conduct the trial.

If the mosquitoes get approved, Oxitec would sell them to local governments, Nimmo said.

Parry refused to say how much Oxitec would charge for the mosquitoes, saying that the process still needs FDA approval.

The mosquito that is released contains a gene that is passed on to females when they mate. The gene then causes the offspring to die before they reach adulthood, which means they can't bite and spread diseases, Nimmo said.

"If you put out enough, then you can crush a population," he said.