PEST CONTROL: NAU scientists find way to deal with Bark Beetle infestation

Across the Western U.S., there is a problem with Bark Beetles, or a bug that infects trees.

According to a map from the United States Forest Service, there are places where 100 percent of trees are infected by Bark Beetles, and enough trees have been killed to cover the State of Washington.

In Arizona, the Ponderosa Pine tree, which is a target of the Bark Beetle, has been under assault for years. The bug infect the outer rings of the tree, just inside the bark. That part is the living part of the tree, which transfers nutrients from the ground below.

Now, however, scientists in Arizona may have a cure, and it involves something that Nark Beetles won't want to hear.

"My lab really focuses on Bark Beetle ecology," said Dr. Richard Hofstetter with the Northern Arizona University School of Forestry.

Resin is the Ponderosa Pine tree's primary defense against Bark Beetles, as the beetles get stuck in it. Under drought conditions, however, trees can't produce enough of it. So, NAU scientists had to come up with a new approach.

"Back in 2006, 2007, I had an undergraduate student approach me with the idea of 'let's stop Bark Beetles,'" said Hofstetter. The student's idea was to use sound, based on the enhanced interrogation techniques used on terrorists.

"Initially, we thought we could play any sound into a tree, and a beetle is not going to like it," said Hofstetter, who went on to say he tried a human voice like Rush Limbaugh, rock music, but nothing worked.

"Maybe we should have played the Beatles to the beetles!" said Hofstetter.

Eventually, however, something did work.

"Just for a few days, we would pipe this sound into trees that were infested. We found that beetles ignored it," said Hofstetter. That sound turned out be the sound of Bark Beetles.

"We came across David Dunn, who is at Sante Fe, and he had these beautiful recordings of Bark Beetles in trees that were being killed," said Hofstetter. They discovered that they could change Bark Beetle behavior by pumping their own sounds into the tree.

"We have two or three or four beetle species in here that all need to avoid each other," said Hofstetter. "We were playing calls from multiple species. I think that helps because the beetle gets confused. It thinks the other species is in its tunnel, and it will act aggressively and push that other beetle out."

In addition, scientists have also discovered that Bark Beetle sounds can be used to stimulate the growth of a Beetle pathogen: a fungus that kills the beetle in just a few days.

Then, a device was invented that delivers the sound into a tree.

"This is the Exciter," said Hofstetter. "It takes energy to run that vibratory unit. It sends the vibrations into this rod, which then goes into the tree, and the tree emits these sounds internally."

Hofstetter said once the device is inserted, the tree is transformed into a big speaker. Hofstetter said the sound resonates inside the tree. In the future, Hofstetter hopes to implant hundreds of these devices at the same time, and transmit a signal to each tree that Bark Beetles won't like at all.

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