Researchers tell pest to bug off

The Laricobius nigrinus tiny beetle from British Columbia is a natural predator of the hemlock woolly adelgid.

Virginia Tech forest entomology researchers are studying a beetle from Japan that may help save a species of trees native to the Appalachian region from becoming completely extinct.

The beetle, named the Laricobius nigrinus, is thought to be a natural predator to the hemlock woolly adelgid that is destroying the Eastern and Carolina hemlocks in the region.

"(The woolly adelgid) didn't get identified until the '50s in Richmond, and really was an insect of little consequence until about the '80s when it started to spread," said Scott Salom, professor of entomology.

As it spread, the insect, known as woolly adelgid, literally sucked the nutrient, from hemlocks in this area, leaving a trail of dead trees wherever it went.

"Most notably in Virginia was Shenandoah National Park, which lost a large amount of old-grown hemlocks in the '90s," Salom said.

Salom said there were two options for elimination: pesticides or biological control. However, Hemlocks grow in small pockets beneath the shade of other trees, and often near water sources, which ruled out pesticide since it would poison many other things besides just the adelgid.

"Biological control, on the other hand, presents a simple, effective solution," said Salom.

Salom found the small, Japanese beetle in British Columbia, and, after much testing, it was released in several isolated areas in 2002.

"I want to stress that this is not a risk," Salom said. "This is a very isolated problem, as both insects live and die on the same tree for multiple generations."

"They are also highly suited to one another, and, as lab tests have shown, do not attack other plants, animals, insects, or people," Salom said.

However, Salom and other researchers want to release several different predators into the area, in order to better confront the adelgid infestation.

Currently, they are looking at a particular insect in Japan, which was not named, preys solely on a nigrinus that is genetically identical to that found here in the United States.

Gina Davis, a graduate student, is continuing this research with a project that involves looking at the dispersal and impact of the nigrinus in Virginia forests.

Davis said she has plans to continue widening and perfecting her sampling technique, as well as following a few new release sites from day one, beginning in the spring, as follow-ups to the previous research.

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