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Entomologist Uses Fungus to Manage Bark Beetles

As Arizona and other western states face ongoing drought conditions, the region’s pine forests are becoming more vulnerable to bark beetles, which attack and kill stressed trees, increasing wildfire danger. Dr. Rich Hofstetter, an entomologist at Northern Arizona University, is working with a fungus that kills the beetles.

“We have isolated particular strains and are testing to see whether these strains are effective against not only the mountain pine beetle, which is the most significant bark beetle in the West, but all the other bark beetles that we have in Arizona that are killing trees, as well as in the eastern United States,” he said.

Following severe drought in 2003, bark beetles affected as many as 1 million acres of trees in Arizona, a figure that has diminished after some wetter years but could worsen with current dry conditions.

In the past, Hofstetter has used other methods to slow the insect’s progression, including using amplified rock music to change their eating patterns.

Now Hofstetter is testing the fungus Beauveria bassiana on a bark beetle species affecting trees from Mexico to Canada. The fungus releases white powdery spores, and when the beetles crawl over them the fungus gets into their bodies and takes over.

Hofstetter was contacted by Montana BioAgriculture to conduct the research and find the most deadly strain of the fungus. The company is developing fungal bio-insecticides to control bark beetles with an environmentally benign product that can be commercially produced and marketed to forest managers.

“The spores penetrate the exoskeleton of the beetle,” Hofstetter said. “And once they get inside, they replicate, they grow and kill the beetle within one to two days.”

When the beetle is dead, the fungus grows outside of the beetle and produces more spores that can be picked up by other insects.

Montana BioAgriculture grows the spores and sends them to Hofstetter, who then puts them in a liquid formula, which he sprays on tree trunks and logs. He hopes that within a year his research will lead to a product that can be used to control infestations.

“We are seeing 80 to 90 percent mortality with the spray,” Hofstetter said.

Scientists in Florida are taking a similar approach by using entomopathogenic fungi to against the redbay ambrosia beetle in order to save avocado trees.


  1. Rush Limbaugh? Really? I’d like to see the empirical analysis of why his voice is potentially any more annoying to an insect than any other voice on the radio. Well, I know why. It would have a nasty surprise to find out Hilary or Barack or Jon Stewart kept the beetles off. But we won’t know because no real science was done here, to find out. Way to go.

    • Crush, you’re right, the beetles very probably wouldn’t know the difference :) Dr. Rich Hofstetter, who conducted the research, wrote the following: “Many years ago (2006) when I first started working on trying to control bark beetles with acoustic technology, we actually did try different music and also human voice to see if it had any impact on bark beetle behavior. One of the human voices we chose to test — because it was readily accessible — was Rush Limbaugh. Our choice to use his voice was not political, but based on ease of access for other scientists to replicate (if we found that it worked).”

  2. I live in California I have loss 100 pine trees in one summer how can I purchase some of your spray to protect the remainder of my trees I would be willing to pay and try anything to stop the outbreak from going any further on my property

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