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Researchers Turn Up the Noise to Battle Bark Beetles

Researchers from Arizona and a composer from New Mexico have teamed up to launch an acoustic counterattack against beetles that have ravaged millions of acres of trees across the West. The tiny insects make squeaking noises as they tunnel through trees, and now a team at Northern Arizona University is using the beetles' own communication against them.

The researchers have been manipulating the beetle sounds, which are above human hearing, and playing them back to the insects. The results drive them buggy: They attack each other, scamper in circles rather than straight lines and have tried to gnaw their way through Plexiglas covering a cross section of a tree in a lab in Flagstaff, Ariz.

"We found pretty amazing results when we would play back the sounds to bark beetles. We could disrupt their behavior," said Richard Hofstetter, an assistant professor at Northern Arizona University's forestry school. The goal is to stop the beetle's relentless march through Western forests. Hofstetter and anthropology student Reagan McGuire were studying ways to disrupt the beetles by bombarding them with sound when they heard of artist, musician and composer David Dunn, who tapped into pinion pine trees in New Mexico to record the bugs at work.

Dunn, president of the Art and Science Laboratory in Santa Fe, turned the insects' birdlike chirps, squeaks and scratching against the backdrop of the trees' noises into a compact disc, "The Sound of Light in Trees."

At Northern Arizona University, McGuire had gone to Hofstetter with his idea of using law-enforcement style "crowd-control sonic bullets," but didn't get anywhere blasting the beetles with heavy metal rock music and Rush Limbaugh broadcasts. The sounds irritated McGuire, but didn't appear to bother the beetles.

Then, Hofstetter and McGuire, drawing on Dunn's work, used the beetles' own communication against them. After identifying certain sounds with certain behaviors, the researchers manipulated beetle noises to interrupt the bugs' mating or provoke them to attack each other.

"There'd be a male and female, they would mate, do all the normal things," McGuire said, "and two hours later, he'd chew her to pieces. That's not natural." The U.S. Forest Service recently approved $40 million to fight the beetle in the Rockies, where 3.6 million acres of pines have been decimated over the last decade in north-central Colorado and southeastern Wyoming.

Dunn, who has traveled the world collecting sounds of nature for his compositions, first started recording the inner life of trees in 2004. He took the kind of small microphone used in greeting cards to record and play, fastened it to a recycled meat thermometer and inserted it into the tree. While concerned about the dying trees and what they signal about climate change, the beetles, “an absolutely fascinating form of life”, have intrigue Dunn.

By JUDITH KOHLER of the Associated Press | Posted: Monday, February 15, 2010 6:15