Florida Keys Mosquito Control District expects that a test release of mosquitoes treated with the bacteria Wolbachia should occur in March, district spokeswoman Beth Ranson said.

The agency and the private company MosquitoMate are still reviewing sites for the release of Wolbachia-treated Aedes aegypti mosquitoes, Ranson said. Possible sites include locations on Key Largo and Stock Island.

The Kentucky-based company MosquitoMate has received state and federal approval to release male Aedes aegypti mosquitoes infected with a bacterium named Wolbachia pipientis.

The lab-reared males, which do not bite, mate with wild females, and the Wolbachia bacterium would be passed along to the females and to the eggs, according to company founder Stephen Dobson.

The bacterium results in chromosomes in the bugs’ eggs not separating and the eggs not being able to hatch, Dobson said.

The trial will test the effectiveness of releasing these mosquitoes in suppressing and eliminating the Aedes aegypti mosquitoes, which are known to carry the tropical diseases Zika and dengue fever.

The mosquitoes in the MosquitoMate test will not be genetically modified like the ones that the British company Oxitec had proposed to release on Key Haven. Oxitec suffered a major setback when Key Haven voters shot down the proposal.

However, a majority of county voters voted in favor of releasing them somewhere in the Keys, which now has the Mosquito Control District and Oxitec searching for a location where the referendum passed and there are enough Aedes aegypti mosquitoes to make the test release scientifically valid.  

The board signed an investigational agreement with Oxitec, which technically means the district can allow the test without bringing the issue back to the board for site-specific approval, according to the district.

However, a new location will have to go back to the Food and Drug Administration for approval. The federal agency previously approved the test on Key Haven.

Oxitec is in discussions with the FDA about granting the company a blanket approval to conduct the test release anywhere in the Keys outside of Key Haven.

“If Oxitec would like to conduct a proposed field trial in another location, the company must submit to the FDA an Environmental Assessment that would cover the new location, in compliance with NEPA (National Environmental Policy Act) requirements, and the process for review would be very similar to the one the company engaged in for the proposed field trial in Key Haven,” FDA spokeswoman Megan McSeveney said Friday.

What will not be part of the new application or part of the FDA’s condition for approval is Key West’s Dr. John Norris’ request for a test to see if Oxitec’s technology leads to an increase in the resistance to antibiotics in humans as a result of a release of genetically modified mosquitoes in Key Haven.

Norris has been calling on the Florida Keys Mosquito Control District board to not approve its agreement with the biotech firm Oxitec until there is a proper review of how genetically modified mosquitoes could lead to an increase in resistance to the drug tetracycline — a medical antibiotic that is used in producing the mosquitoes. Tetracycline is one of the few antibiotics that ‘superbugs” respond to, says Norris. 

Tetracycline is a key component in ensuring Oxitec’s genetically modified mosquitoes die after being born. The antibiotic acts as a switch to control the mosquito’s other genes.

Both Oxitec and the FDA said the question was asked and answered as part of the first environmental assessment and will not be studied further.

“The environmental assessment relevant to Oxitec’s originally proposed field trial in Key Haven concluded that the likelihood that the production and release of OX513A mosquitoes would lead to development of antimicrobial resistant bacteria is extremely low,” McSeveney said. 

“This is in part because resistant bacteria, even if present in the larval or pupal stages, would be highly unlikely to be present in adult OX513A mosquitoes due to the fact that gut bacteria are lost during mosquito metamorphosis from pupae to adults. Antimicrobial resistance arising in bacteria in the rearing water and the subsequent transfer of this trait to other bacteria that could cause food or water-borne diseases would also be highly unlikely due to the short duration of the mosquito life cycle as well as the short duration of the trial.”

She added that this conclusion “is relevant only to Oxitec’s originally proposed field trial in Key Haven” but left unexplained why a new potential field test site would not need additional testing.