Laboratory scientists have created killer mosquitoes designed for one purpose: to mate with and kill disease-carrying mosquitoes.
OK, that’s really two things, but the goal is singular: fewer mosquito-borne illnesses.
They’re called ZAP Males. Researchers in Kentucky have bred male mosquitoes with a specific bacterium that kills their chances of offspring when they mate with females.
“Any females that mate with our males effectively become sterile,” said Jimmy Mains, the chief science officer with MosquitoMate Inc., which developed the technology. “They still lay eggs, but they don’t hatch.”
On Wednesday, the Environmental Protection Agency announced approval for ZAP Males to be marketed and used in 20 states and the District of Columbia for the purpose of eliminating the Asian tiger mosquito, an invasive species native to East Asia.
ZAP Males target only this species, also known as Aedes albopictus — a particularly nasty, biting mosquito that attacks during the day and has the ability to transmit a number of diseases, including dengue fever and chikungunya.
Named for the white stripes on their dark bodies, Asian tiger mosquitoes have flitted across the U.S. over the past three decades and can be found in California, almost all of the Southern states and the Northeast.
“This is still a relatively new species, and it’s still spreading out. It’s not done yet,” Mr. Mains said. “Every year, there’s new territory that it invades. Probably the most recent is its invasion of California.”
The goal isn’t to eliminate all mosquitoes — just this species, which breeds in standing water in small containers and thrives in warm climates.
ZAP Males aren’t fast-acting like chemical pesticides; instead, they decimate the mosquito population over time. But one of ZAP Males’ benefits is being a nonchemical pesticide with virtually no runoff into the surrounding population, Mr. Mains said.
“The current control tool set is not adequate in controlling this species. If they do, they are using copious amounts of chemical insecticides that not only are really expensive but have detrimental nontarget effects also,” he said.
ZAP Males are designed to target only the invasive species without affecting native mosquitoes, thus preventing an upset of the ecological balance.
“The nice thing about our approach is it’s species specific, so the male mosquitoes we release only target their counterpart and have no effect on native species that do play an important ecological niche here,” Mr. Mains said.
The EPA’s approval allows MosquitoMate to market and sell its ZAP Males for five years in California, Connecticut, Delaware, Illinois, Indiana, Kentucky, Massachusetts, Maine, Maryland, Missouri, New Hampshire, New Jersey, Nevada, New York, Ohio, Pennsylvania, Rhode Island, Tennessee, Vermont, West Virginia and the District of Columbia.
Mr. Mains said the threat of a dengue fever outbreak in the U.S. is relatively low compared with other parts of the world. Outbreaks in Florida, Texas and Hawaii affected a relatively low number of people. The greater threat is the biting nuisance, which can frustrate communities, he said.
“Some parts of Lexington, Kentucky, people don’t go outside during the summer, and that affects a whole host of downstream issues — child activities, home prices, so forth,” he said.
Researchers in Mexico and Brazil have identified some Asian tiger mosquitoes infected with the Zika virus. However, the tiger-striped insects aren’t the primary carriers of Zika, which can cause flulike symptoms and birth defects like microcephaly — the underdevelopment of the brain and skull.
The ZAP Male technology is being developed for the Asian tiger’s sister species — Aedes aegypti, the primary carrier of the Zika virus — and researchers have finished field-testing it in the Florida Keys and California. MosquitoMate is hoping for federal approval within the next few years, Mr. Mains said.
This year, 347 cases of Zika have been registered in the U.S. The vast majority were reported by travelers returning from abroad. Only two cases of Zika transmission were attributed to the bite of a mosquito, and three cases were attributed to sexual intercourse with an infected person.
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