Destructive bark beetles have been munching their way through vast tracts of pine forest in Western Canada and the United States. Researchers may have found a line of defense against the bugs: sonic warfare. Scientists at Northern Arizona University have found that loud sounds can repel bark beetles, reports The Adventure Life blog.
It took some experimentation to home in on the most annoying soundtrack. The scientists at first blasted the beetles, which were living in pine cross-sections dubbed "ant farms," with heavy metal and Rush Limbaugh commentary played backward. A plausible hypothesis, to be sure:
But “after a few minutes they ignored it,” said Richard Hofstetter of NAU’s School of Forestry. “They seem to habituate to the sound.”
So then Hofstetter and his team recorded the noises the beetles themselves make, tweaked them, and piped them back into the ant farms. The results were nearly instantaneous.
“We could use a particular aggression call that would make the beetles move away from the sound as if they were avoiding another beetle. Or we could make our beetle sounds louder and stronger than that of a male beetle calling to a female, which would make the female beetle reject the male and go toward our speaker. We found we could disrupt mating, tunneling, and reproduction. We could even make the beetles turn on each other, which normally they would not do.”
The scientists have developed an “anti-beetle boom box” that will cost about $100 a tree—too expensive and labor-intensive to use on every tree in the forest, no doubt, but for possible use on high-value trees or, The Adventure Life speculates, a wall-like defense line against the invasion. Call it a wall of sound.