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NMSU biology professor leads research into bark beetle defense

An assistant professor in New Mexico State University’s Department of Biology recently published an article detailing the effects bark beetles have on trees, the economy and what characteristics are important in preventing bark beetle damage.


Bark beetle on a piece of wood
A mountain pine beetle (Dendroctonus ponderosae) that recently emerged from the pupal stage crawls across the interior side of pine bark removed from a dying tree. (Courtesy photo)
Mountains with snow and pine trees below with red patches
A patch of lodgepole pine trees recently attacked and killed by bark beetles in the Colorado Rocky Mountains are distinguished by their red needles. Bark beetle attacks often begin in areas where trees are highly stressed and spread from these “epicenters” to nearby trees and forest stands. (Courtesy photo)
Head and shoulders of a man with a beard and mustache
Scott Ferrenberg, NMSU assistant professor of biology, recently published a paper in "Ecosphere" about the impact of bark beetles. (Courtesy photo)

Scott Ferrenberg is a new faculty member at NMSU. After receiving his master’s in entomology from the University of Maryland in 2002, he went to work for Sequoia National Park in California.

“My main marching orders were to help the park service determine whether fire-mitigation strategies were going to increase bark beetle attacks,” he said.

His research into bark beetles continued off and on for the next decade. Then, when he went to the University of Colorado in 2014 to work toward his doctorate, “there was an unprecedented bark beetle epidemic sweeping across the West.”

Such infestations are not uncommon, Ferrenberg said, though the magnitude of this particular infestation, lasting from the early 1990s to about 2012, was the worst many entomologists could remember.

“These bark beetles are natural to the forests of North America,” Ferrenberg said. “Bark beetles are bad from our point of view because they kill trees that are important economically,” Ferrenberg said. “There are bark beetles associated with almost any tree on earth. The kind we’re referring to are just a handful of genera that attack conifers.”

Conifer trees are used to produce lumber for building structures and furniture, as well as paper.

“These bark beetles attack conifers for the purpose of reproduction,” Ferrenberg said. “To be successful at that, they need to be able to tunnel just underneath the bark and live there. To do that they have to kill the tree.”

The beetles descend upon the trees by the hundreds or even thousands and overwhelm the tree’s defenses, generalizing the decay of the tree rather than just affecting a particular portion of the tree.

The best practices in terms of defending against bark beetle attacks are not clear, Ferrenberg said, because there haven’t been any breakthroughs in terms of helping forest managers predict where an outbreak may occur.

“The work I’ve been doing is identifying some defense traits that are very useful for predicting susceptibility to bark beetles,” Ferrenberg said.

Based on his research, Ferrenberg and his collaborators on the article, which was published in October of this year in “Ecosphere,” surmise high-elevation and high-latitude forests seem to be more heavily damaged by bark beetles than lower-elevation, lower-latitude forests.

“One really intriguing possibility is that because those places are colder, they may just have less history of dealing with insect pests because cold weather will restrict the activity of insects,” Ferrenberg said.

This may mean that the trees in lower-elevation lower-latitude forests evolved to withstand bark beetle infestations, such as developing anti-insect chemicals and resins.

The next step in Ferrenberg’s research is to collect data on how the latitudinal gradient from the New Mexico/Texas border all the way up to British Columbia affects bark beetle infestations.