Foul Stink Bug Targets Wine Grapes

The stink bug has a new target: wine grapes.

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The Asian brown marmorated stink bug that has swept into 33 states and the District of Columbia, destroying peaches and apples along the way, has a new target: wine grapes. Researchers tasked with tracking the bug and finding a way to kill it now say that wineries in Virginia and out west in Oregon, Washington, and parts of California are under attack.

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"Some vineyards and some growers have been wiped out in the last year," says Virginia Rep. Frank Wolf, who is taking the lead in Congress on the issue. "They are devastating the vineyards."

With peaches, apples, and even berries, the major issue is the visible damage a stink bug does. On apples, for example, the bug will insert its tongue into the fruit and suck, leaving a "corky dry area" that's visible to shoppers, says Tracy Leskey, an Agriculture Department entomologist who's co-leading a national working group researching the stink bug. "It looks bad," she says, though it won't affect the flavor.

But with grapes, the bugs stick to the clumps of fruit during the picking season and can end up in wine presses. Wolf says that just 10 stink bugs crushed into one ton of grapes can ruin the wine. Finding a couple on each hand-sized clump is typical, so winery workers have to pull the half-inch-long bugs off by hand or use an organic pesticide at harvesting, he says.

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Wolf adds that other crops are also now under stink bug attack, including corn, tomatoes, and soybeans. Leskey says the shield-shaped bug has also become a huge pest in homes, a double whammy few other insects pose, as it moves across the country. "They are a very good hitch-hiker. The potential for moving across the country is high," she adds.

Because the stink bug arrived in the United States only in the late 1990s, there hasn't been enough time to find the right pesticide or natural foe, though the Environmental Protection Agency is considering allowing fruit growers to use dinotefuran, a powerful poison.

One possibility under study is a tiny wasp, the size of a comma in this story, that is the stink bug's natural predator in Asia where it helps to keep the offensive bug's population in check. The non-stinging wasp lays its eggs in the eggs of the stink bugs, on which the baby wasps then chow down. But the entomologists are being extremely cautious to make sure the wasp wouldn't cause any other damage. Says Wolf, "You've got to be careful that you don't introduce something that is as bad or worse than what you have."

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Kim Hoelmer, the research entomologist studying the wasp, says it so far hasn't shown to be dangerous to anything else. "They only attack stink bug eggs. If they don't find stink bug eggs, they die," he says. "We know it's not likely to become a pest," he adds.

But testing will take time, about two more years, before the wasp will be approved and introduced to orchards, gardens and vineyards.

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