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How best to kill skeeters? Experts pitch their plans

Florida Keys Mosquito Control District leaders want to load up an arsenal of tools to combat mosquitoes that carry new and old diseases.

It’s not just Zika virus they’re concerned about, which causes flu-like symptoms and smaller-than-average brains in infants, but the possibility of an outbreak like dengue or yellow fever in the Florida Keys.

Tuesday at a workshop in front of the Mosquito Control Board, experts and scientists working on methods for mosquito control talked about their projects, like male bugs sterilized through gamma radiation, bugs infected with natural bacteria and genetically modified bugs.

Each method has the same goal: To sterilize males and release them to mate with females that produce eggs that never hatch. This lowers the population of disease-carrying bugs, they say.

Speakers Tuesday included Dr. Anthony Llau, researcher for Global Health Consortium; Bob Eadie, Monroe County Health Department director; David Hoel, assistant director of Lee County Mosquito Control; Jimmy Mains of MosquitoMate; Dr. John Norris of Key West; Dr. Derric Nimmo of Oxitec; and Dr. William Petrie, director of Miami-Dade Mosquito Control.

Irradiated bugs

Hoel talked about Lee County’s plans to release mosquitoes sterilized through gamma radiation starting in 2019. A colony of locally collected bugs is kept on the property of Lee County Mosquito Control, where they feed on chickens and mate, he said.

The X-ray machine has not arrived yet, but once it does, male mosquito eggs from the colony will be put in a pupal separator, then run through the X-ray machine to be sterilized. It’s the gamma rays that sterilize the bugs.

“We can sterilize 200,000 pupae at one time,” Hoel said, and the males would be released to mate with wild females and produce eggs that never hatch.

Lee County Mosquito Control is funding the project on its own, Hoel said.

“We’re rolling the dice and don’t know how well this is going to work,” he said.

GM bugs

British biotech company Oxitec wants to release its male mosquitoes that are reared with a self-limiting gene. So when the males, which don’t bite, are released into the wild to mate with wild females, the gene is passed on and the offspring never survive to adulthood, Nimmo said.

Oxitec submitted a new application with the Environmental Protection Agency in December and the EPA now has until July to make a decision on whether it will issue an experimental-use permit for a trial in the Keys.

Should the EPA approve the trial, the genetically modified male mosquitoes would be reared in Marathon, Nimmo told the Keynoter. Mosquito eggs would be shipped from Oxitec’s lab in the U.K., he said. In Marathon, the eggs would be sorted out from the females.

“The females are killed as pupae and the males are allowed to pupate,” he said. It is these males with a self-limiting gene, caused by the antibiotic tetracycline, that would be released to mate with wild females. A trial site has not been selected.

Norris

The use of tetracycline is a concern for Norris and a group of Lower Keys doctors because of bacteria that may be riding on the backs of the mosquitoes, seeing as how bacteria develop resistance to antibiotics after exposure to too much or too little. The surviving bacteria can become even more powerful and resistant to medicine down the road.

Norris told Mosquito Control District commissioners it is not the release the doctors are worried about — they want the mosquitoes to be swabbed for bacteria. They’re also concerned about the use of tetracycline.

“I’m not saying Oxitec is misusing antibiotics, I’m not,” Norris told commissioners, calling tetracycline an important tool in public health. “I’m saying with the greatest respect to what you do, the most important thing to realize is the doctors want data, data on something we’re not allowed.”

Commissioners suggested Norris submit his public comments to the EPA when the public comment period begins. That could happen soon, and is part of the EPA’s process when deciding whether to give Oxitec an experimental-use permit.

Wolbachia

MosquitoMate, which did a trial in the Lower Keys last summer, is releasing male mosquitoes infected with the natural bacteria Wolbachia in South Miami through July.

In 2017, over a five-month period, 1,259,000 male mosquitoes were released on Stock Island.

“We did observe declines in egg hatch throughout the project at sites exposed to released males only,” said Mains said, adding there was positive public response.

The eggs don’t hatch due to the Wolbachia, which is found in 50 percent of insects and is not harmful to humans, according to Dr. Stephen Dobson, founder and chief executive of MosquitoMate.

“We don’t have a trial for 2018 in the Keys, but there’s a lot we could build on from the trial we performed last year,” Mains said, adding South Miami’s trial will be about seven times as intense as the one done in the Keys last year.

Reaction

Emerging viruses are not new, Llau said, adding they are a burden around the world. He showed a slide of viruses carried by mosquitoes globally and the spike in mosquito-borne diseases over the last 30 years.

“There’s a really sharp increase in the past decade,” he said.

He also said climate change has an impact and disease-carrying bugs could be moving north in America, adding “$60 billion a year is the cost of climate change and infectious diseases.”

“Spraying is not going to do it,” Eadie said of ridding disease-carrying bugs in the Keys. “These presentations prove how things really have to be considered to go forward because the diseases we’re seeing throughout the world are changing and they’re still mutating.”

Katie Atkins: 305-440-3219

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