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 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 beetle sounds, which are above human hearing, and playing them back to the insects. The results drive them buggy: They attack one another, 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 beetles’ 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 piñon 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.”
“The massive die-off of trees just sort of made me curious — if these things are that energetic, maybe they’re making interesting sounds,” Dunn said.
At Northern Arizona University, McGuire had gone to Hofstetter with his idea of using law-enforcement-style “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, started using 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 one another.
“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.”
Scientists have used beetles’ own chemicals to try to control them. Forest managers are watching to see whether acoustics offer another route, said Skye Stephens, an entomologist with the Colorado State Forest Service.
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 past decade in north-central Colorado and southeastern Wyoming.
Millions of more acres in Arizona, New Mexico, Montana, Idaho, Washington, Oregon and western Canada have been infested by the beetle, which is the size of a rice kernel.
Such outbreaks are part of natural cycles in forests, but state and federal land managers say this epidemic — the largest on record — has been aggravated by a lack of long frigid bouts to kill the bugs and drought that has weakened the trees.
“It kind of breaks all the rules,” Stephens said of the infestation.
