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EPA approves release of weaponized mosquitoes in NH to combat Zika virus

Sunday News Correspondent

November 28. 2017 2:03PM

A new biotic approach to controlling mosquitoes could turn the tide on summertime's annoying little pests.

New Hampshire is one of 20 states with a time-limited registration for a biopesticide aimed at reducing a type of mosquito known to spread diseases such as the Zika and West Nile viruses, dengue, chikungunya and yellow fever.

While it might sound like the opening of a science-fiction movie, this new EPA-approved pesticide releases male Asian Tiger mosquitoes (Aedes albopictus) infected with a strain of Wolbachia, a naturally occurring bacteria, into the environment. These males then mate with females, but the bacteria is designed to prevent the skeeters' offspring from surviving.

"In some mosquitoes, when a Wolbachia-infected male mates with a female, the sperm and eggs are unable to form a viable offspring and the eggs die," said New Hampshire state entomologist Piera Siegert. "This would be a critical point at which you could effectively reduce overall mosquito populations. Fewer viable eggs would mean fewer adults, reduced disease transmission, etc."

The strain of Wolbachia is specific to arthropods and some nematodes, known as roundworms, and does not transfer to the female. Male mosquitoes do not bite or transmit disease.

The EPA registered the new product - ZAP Males from Kentucky-based MosquitoMate Inc. - earlier this month. All six New England states are among the 20, plus the District of Columbia, with a five-year registration limit to sell the Wolbachia-infected male mosquitoes.

The EPA said the release of these mosquitoes does not expose humans to the bacteria.

Siegert said while the idea is intriguing and could become more important in the Granite State as the climate changes, it will not have a significant immediate impact here.

"The reason is that we don't have established Aedes albopictus populations in the state. I believe that there have been some interceptions, and Aedes albopictus is in southern New England, so a possibility exists that the mosquito could have some survivability in parts of the state," Siegert said.

"I don't even know if the company would do the releases in New Hampshire given the low/unknown Aedes albopictus populations. Often permits like these condition where the organism can be released, not that it will be released," she said. "New Hampshire may be on this list simply because it is of similar climate, not that it is a good location to do the work."

MosquitoMate did not return a request for comment.

Mosquitoes in New Hampshire don't carry the Zika, dengue, chikungunya or yellow fever viruses, but the West Nile virus has been found in insects trapped here, including two batches of mosquitoes in Manchester this summer. While most people infected with West Nile don't show any signs, some develop flu-like symptoms and a small percentage develop serious conditions, including encephalitis or meningitis.

Robert Bruleigh, with the Division of Pesticide Control in the N.H. Department of Agriculture, Markets and Food, said any new method to deal with mosquitoes is useful to residents in New Hampshire.

"I'm not a mosquito expert, but if they're having a longer period where they can successfully reproduce, then anything more that we can add to our toolbox of ways to deal with them is beneficial," he said. "We literally have over 12,500 products registered now (in the state) of all pesticide types."

The EPA says experimental use permits were issued for the ZAP Males product to test it in select locations for three years prior to the registration application. Those samples, in Kentucky, New York and California, demonstrated the product is able to reduce Asian Tiger mosquito populations by upward of 80 percent.

Just as there are diseases that infect mammals, different species in the Wolbachia genus are specific to certain insect hosts and are common in the environment.

Siegert said that since Wolbachia was first detected in the early 20th century, there has been interest in trying to use the bacteria to affect pest insect populations.

"It's an intriguing system - the disease has evolved to infect insects and that infection causes some kind of physiological response in the insect," Siegert said. "The question then becomes whether there is a way to manipulate this natural system to control pest insects, thereby reducing reliance on chemical control."

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