August 21, 2013

Mosquitoes resist our arsenal of controls

Scientists say the insects will likely gain pesticide resistance and benefit from climate change.

By SETH BORENSTEIN The Associated Press

Ryan Miller
click image to enlarge

Ryan Miller peers through plants in his Arlington, Va., yard Monday. He has been lobbying his local government to break out the pesticides this year to fight mosquitoes, which can carry lethal diseases.

The Associated Press

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The tiny mosquito all too often has man on the run. And this summer, it seems even worse than usual.

"You can't get from the car to inside our house without getting attacked, it's that bad," high school teacher Ryan Miller said from his home in Arlington, Va. Minutes earlier, he saw a mosquito circling his 4-month-old daughter -- indoors.

Experts say it's been a buggier-than-normal summer in many places around the U.S. because of a combination of drought, heavy rain and heat.

It may be worst in the Southeast, which is getting hit with three years' worth of bugs in one summer, said Jonathan Day, who studies insects at the University of Florida.

Two years of drought were followed by incredibly heavy rain this year. During dry spells, mosquito eggs often didn't get wet enough to hatch. This year's rain revived those, along with the normal 2013 batch.

In parts of Connecticut this summer, mosquito traps had double the usual number of bugs. Minnesota traps in July had about triple the 10-year average. And in central California, traps had five times as many of one key species as the recent average.

Humans have been battling the blood-drinking bugs for thousands of years, and despite man's huge advantages in technology and size, people are not getting the upper hand. Just lots of bites on the hand.

"We have to keep fighting just to hold our own," said Tom Wilmot, past president of the Mosquito Control Association and a Michigan mosquito control district chief. And in some places, he said, the mosquitoes are winning.

In southwestern Florida around Fort Myers, Lee County mosquito control was getting more than 300 calls per day from residents at times this summer, a much higher count than usual. But the more impressive tally was the number of bugs landing on inspectors' unprotected legs: more than 100 a minute in some hotspots, said deputy director Shelly Radovan.

Across Florida near Vero Beach, Roxanne Connelly said there have been some days this month when she just wouldn't go in the backyard. It's been too bad even for her -- and she's a mosquito researcher at the University of Florida and head of the mosquito association.

Many communities fight back by spraying pesticides, but mosquitoes are starting to win that battle, too, developing resistance to these chemicals. Soon many places could be out of effective weapons, Connelly and other mosquito-fighters said.

Miller, who teaches environmental sciences, said he normally would oppose spraying but has been lobbying for the county to break out the pesticides this year. The county told him there was no money in the budget and recommended he hire a private pest control business, he said.

The type that buzzed his daughter -- the Asian tiger mosquito, named for its striped body -- hit the U.S. a quarter-century ago in a batch of imported scrap tires in Houston and eventually spread to the Northeast, the Midwest and, in 2011, the Los Angeles area.

Climate change is also likely to worsen mosquito problems in general because the insects tend to do better in the hotter weather that experts forecast, said Chet Moore, a professor of medical entomology at Colorado State University.

Mosquitoes, of course, can be more than a nuisance: They can spread diseases. In the U.S., the biggest mosquito-borne threat is West Nile virus. Last year, there were a record 286 West Nile deaths, but this year appears to be milder.

Worldwide outside the United States, mosquito-borne diseases kill far more people than sharks, snakes and bears combined, with more than 600,000 deaths from malaria each year in poorer countries.

People should wear light-colored clothing -- dark colors attract mosquitoes -- long pants and long sleeves; get rid of standing water, where mosquitoes breed; and use repellents with the chemical DEET, experts said.

But even those substances may not work for long. Mosquitoes could be developing resistance to repellents as well as insecticides, said mosquito researcher James Logan at the London School of Hygiene and Tropical Medicine.

"It's an arms race," he said. "I always think they are one step ahead of us."

 

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