Stink Bugs vs. Wasps: OSU Pits Pest Against Pest

Hidden deep in the shadows, seeking refuge from winter’s chill, an invader may be lurking in your attic. Although you may not typically think of a small insect as a threat, organisms that have been transported from their native lands can have devastating effects on ecosystems as well as on human-created agricultural systems.

The brown marmorated stink bug was accidentally introduced to the northeastern U.S. around 1996 and has been spreading westward ever since.

“Unfortunately, it has been detected in many of Oregon’s major agricultural areas and the populations are increasing,” entomologist Vaughn Walton told OSU.

The stink bug is not a picky eater, so it’s a potential threat to a wide variety of agricultural crops. Researchers throughout the country are studying strategies to effectively manage the invader. One possible approach, known as biocontrol, involves the introduction of the pest species’ native enemy to keep its population in check. In this case, scientists are considering the release of a tiny wasp imported from China that lays its eggs inside of the stink bug’s eggs.

The use of biocontrol has a storied history. In 1868 the cottony-cushion scale, a small insect native to Australia, arrived in California and began to wreak havoc on the burgeoning citrus industry. Around 1888, a government scientist who was surveying the sub-continent discovered that the vadalia lady beetle was a major predator of the scale. The beetle was immediately imported and released in the U.S. Within a few years, at a cost of about $1,500, the scale infestations had been eliminated, thus saving the citrus industry millions of dollars annually.

On other occasions, however, biocontrol has failed disastrously, leading to outbreaks of control species that have caused greater damage than the initial pest. Perhaps the most well-known case involves the 1935 introduction of the cane toad to Australia. Originally imported to manage beetles that were attacking sugar cane fields, the toad’s population soon grew to huge numbers. Today the toxic toad is itself considered a pest. In addition to it directly preying on native species, it also poisons humans and their pets, competes with native insectivores, and may carry diseases that affect native frogs and fishes.

Bearing these historical examples in mind, it seems prudent to approach the current situation with caution. Peter Shearer, who is leading OSU’s stink bug research, acknowledges the need to carefully weigh the costs and benefits of biocontrol.

“We want to do this right,” he told OSU. “Rarely do we have an ample opportunity to deal with a problem that has the potential to be this bad.”

by Mike Vernon

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