Tiny wasps could curb a massive stink bug invasion

USDA researchers in Delaware are working to find a safe way to dispatch the region's newest pest

February 28, 2011|By Mary Carole McCauley, The Baltimore Sun

Newark, Del. — — Maryland's newest terrorist life form — the brown marmorated stink bug — may eventually meet its archnemesis in the form of a tiny prizefighter of a wasp from Asia.

The parasitic wasps that are being raised in quarantine in a Delaware laboratory are not glamorous-looking bugs. They are black, stocky and about the size of the comma in this sentence.

But they are uncommonly efficient at hunting down and injecting their offspring into stink bug egg masses. In true horror-movie fashion, the larvae consume the stink bugs from the inside out. When the wasps grow into adults, they chew their way out, procreate — and go on the hunt for more stink bug eggs.

"Tests have shown that these wasps will destroy up to 80 percent of the stink bug population," says Kim Hoelmer, the U.S. Dept. of Agriculture scientist in charge of the project. "They're efficient egg-stinging machines. For something so tiny, it's absolutely amazing the behaviors that are hard-wired into their little brains."

Stink bugs aren't a threat to human health. And if they were merely odoriferous and annoying, chances are that the nation's top bug experts wouldn't be going to so much trouble to locate and develop an insect assassin.

But not only do stink bugs represent an unprecedented threat to U.S. vegetable farms and orchards, they have the potential to drive up food prices just when the nation is struggling to emerge from a recession. Bug experts say that the Asian wasp may be one of their best tools for keeping the stink bug population down to a manageable buzz.

"I've never seen such a serious pest enter the U.S. agricultural system," said Tracy Lesky, research entomologist with the West Virginia-based Appalachian Fruit Research Station, "if only because they attack so many crops."

Populations of stink bugs have been increasing steadily in Maryland for the past five years, and are poised to invade the state in record numbers during the coming growing season.

"I think we're going to have a bumper crop," says Michael Raupp, an entomologist at the University of Maryland. "If 1 in 10 people had stink bugs in 2010, 9 in 10 people will have them in 2011."
Hoelmer and his team have been importing and studying the parasites since 2005.