UW Students Research Shines New Light on Mountain Pine Beetles

Bark beetle epidemics have prompted many studies over the years, but the role of parasitoid wasps and other beneficial natural enemies of the mountain pine beetle is not well understood because of the difficulties in studying insects that live under the bark of trees.

For the past two years, University of Wyoming entomology master’s degree student Lawrence Haimowitz has been studying which natural enemies are present in Wyoming to help better understand their role. His work was funded with UW College of Agriculture and Natural Resources ecosystem science and management entomology Professor Scott Shaw via a grant from the Wyoming Agricultural Experiment Station.

During his research, Haimowitz refined a couple of methods for studying mountain pine beetles and their insect associates in standing trees, where the beetles spend most of their life cycle. His research also found persistent, low-level beetle mortality in limber pines in southern Wyoming forests following the most recent epidemic.

When Haimowitz began his studies in the Pole Mountain area of the Medicine Bow National Forest, limber pines were the only trees with active mountain pine beetles that he found. No one is certain why this is the case.

“The same thing is happening in the whitebark pine as well, where researchers found beetles when there were no more beetles in lodgepole pines,” Haimowitz says. “There’s some speculation that maybe it’s a better host for the beetle.”

Historically, limber pines are not as well studied as lodgepole and ponderosa pine, which are both major sources of wood products, or whitebark pine, which is recognized as a keystone species in high-elevation ecosystems.

Haimowitz’s two methods include traps to capture beetles and their associates as they emerge from infested trees, and predator exclusion, which hadn’t been applied to mountain pine beetles previously. For predator exclusion, an enclosure is attached to the tree before beetles attack, which protects the beetles from natural enemies in that section of trunk.

Just before the beetles complete their life cycle in the tree, the tree is cut into sections, and the number of beetles coming from the protected section can be compared to the number of beetles coming from the portion exposed to natural enemies. Although the sample size was small, Haimowitz found 90 to nearly 100 percent fewer beetles in sections exposed to natural enemies.

Each year, Haimowitz has improved on the enclosure design, and he plans to publish the results of his work.

For Haimowitz, entomology is a second career. Originally from Belle Mead, N.J., he enjoyed a successful career in California in environmental safety. He moved to Wyoming when he married longtime state resident Robin Hill. He decided to pursue entomology on retirement, a passion he’d first discovered as a biology undergraduate at San Jose State University. Hill now is helping him create a database for his specimens.

As he pursues his Ph.D., Haimowitz hopes to do more taxonomic work, as well as to continue another project, which looks at parasitoid wasps in shortgrass prairie. He also hopes to collaborate with Canadian researchers to continue his predator exclusion studies on mountain pine beetles in that historically colder climate.