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USDA to use spray to curb moth spread
Monday, June 17, 2013
By BEN R. WILLIAMS - Bulletin Staff Writer
The dreaded gypsy moths have reared their heads in southside Virginia, and state and federal agricultural agencies are looking to stop the infestation before it can spread.
Beginning the week of June 17, the Virginia Department of Agriculture and Consumer Services (VDACS) and the U.S. Department of Agriculture (USDA) will join forces in an aerial insecticide spraying of areas in Patrick County and surrounding counties, according to an article from The Associated Press.
The spray is no ordinary insecticide, according to the VDACS website. Instead, it is a gypsy moth mating disruption pheromone.
Male moths use their antennae to detect female mating pheromones, which are distinctive chemicals that the females release into the air. According to asknature.com, some species of moth can detect a single pheromone molecule in a cubic yard of air. Male moths use these chemicals to locate female moths and mate.
According to the VDACS website, the chemical being sprayed locally is a synthetic version of the female moth pheromone, which has been used in other areas for several years with positive results.
By saturating a large area with the female pheromone scent, male gypsy moths will not be able to pinpoint the location of the real female gypsy moths, which will prevent mating and result in fewer gypsy moths in the future.
VDACS adds that while the local aerial spraying is scheduled for the week of June 17, the schedule depends on both weather conditions and the moth population’s stage of development.
Gypsy moths are native to Europe, but they have been a pest in the U.S. since the mid-1800s, according to Dr. Joe Keiper, executive director of the Virginia Museum of Natural History.
“It was introduced in New England and spread very slowly ... because the female doesn’t fly very much,” Keiper said. “The female is a big chunky organism, and a very weak flier. The problem is, of course, we move firewood, things like that, so we end up moving the eggs. That’s what causes it to spread ... very slowly across the eastern United States.”
According to Keiper and online sources, gypsy moths were introduced accidentally in Medford, Mass., in 1869 by Professor Étienne Léopold Trouvelot. Trouvelot had hoped to interbreed the gypsy moths with silkworm moths to create a silk industry. Unfortunately, several gypsy moths were released by accident, and the moths began their slow spread down the eastern seaboard.
The reason that the moths are a pest, Keiper said, is that they eat tree leaves, and in sufficient numbers, they can eat all of the leaves off of a tree.
“Just about every area in the eastern United States has gotten defoliated at one point,” he said. “Fortunately ... that doesn’t mean (the tree is) going to die. You would need to defoliate a tree, big trees anyway, two, three, (or even) four years in a row.
“It’s a mess they make, that’s for sure,” Keiper added. “But if you get an outbreak that lasts long enough, then your trees are going to have a problem. If you have one of these multi-year outbreaks, you can lose a number of trees.”
Spraying to control the outbreaks, Keiper said, can help prevent that.
What makes gypsy moths particularly devastating pests, he said, is the variety of leaves they eat.
“You’ve got two different kinds of herbivores in nature,” Keiper said. “You’ve got those that are specialists — they feed on one or a few (types of) plants — then you’ve got the generalists that can survive on plants across different plant families.”
As an example, he said, the emerald ash borer is a destructive pest insect, but it only targets ash trees.
Gypsy moths, on the other hand, can target more than 300 varieties of plants, making them difficult to eradicate.
While the spray that will be used in Patrick County is effective against gypsy moths, Keiper said people need not worry.
“I don’t think you’d want to be standing under the helicopter when it’s spraying the stuff,” he said, but “it’s not toxic to us.”