RICHMOND—Agricultural researchers have discovered a small wasp that could have a big impact on crop-ruining brown marmorated stink bugs.

The stink bugs feed on fruits and vegetables, as well as corn, cotton and soybeans. Pesticides labeled for use against brown marmorated stink bugs are mostly ineffective, and the pest has no natural enemies in the United States.

“If researchers can find a natural predator that will control these pests, that will definitely help our fruit, vegetable and crop farmers,” said Spencer Neale, a commodity marketing specialist for Virginia Farm Bureau Federation. “This type of stink bug is more aggressive and resistant than other species.”

The U.S. Department of Agriculture’s Agricultural Research Service has been working to develop management programs for the stink bug.

At the ARS laboratory in Newark, Del., research entomologist Dr. Kim Hoelmer is evaluating a tiny wasp from Asia that attacks the stink bug’s eggs.

The female Trissolcus wasp searches for eggs on host plants. When she finds them, the wasp deposits her eggs inside the stink bug’s eggs. After the wasp eggs hatch, the young wasps consume the stink bug eggs.

Trissolcus wasps do not attack other kinds of insects, animals or plants, according to Hoelmer.

“The brown marmorated stink bug is a real problem,” said entomologist Dr. Chris Bergh at Virginia Cooperative Extension’s Alson H. Smith Jr. Agricultural Research and Extension Center. He explained that the stink bug tends to move from one host to another depending on the season. They also feed on ornamental plants in managed landscapes, as well as on native plants.

“That’s why they are such pests, because they have such a wide host range,” he said.

Brown marmorated stink bug damage to agricultural crops in mid-Atlantic states was first observed in 2008, Neale said, and by 2010 the bugs had caused serious damage.

Bergh said the bugs don’t seem to be doing quite as much damage so far this year, but no one can predict what will happen for the rest of the growing season.

When stink bugs suck the juice from fruits, vegetables and plants, the resulting brown spots and shriveled appearance leave products unsellable.

Contact Neale at 804-290-1153.