Hidden in Plain sight: synthetic pheromone misleads beetles, protects trees

Abstract

In the last decade, pine forests throughout much of the western United States have been ravaged by the mountain pine beetle (Dendroctonus ponderosae). This bark beetle is native to the United States and has been responsible for massive tree kills in the past. The current outbreak, however, has been notably severe and wide ranging and the effects have been more dramatic and longer lasting.

Scientists have documented infestations in areas never before recorded. The insect has expanded its host selection from its more-preferred species of pine— ponderosa, lodgepole, limber, whitebark, and sugar—to afflict species relatively untouched in previous outbreaks, such as Engelmann spruce and jack pine.

Rob Progar, an entomologist with the U.S. Forest Service’s Pacific Northwest Research Station, recently completed a research project in a series of bark beetle studies that evaluates how well a synthetic version of the pheromone verbenone protects trees during a mountain pine beetle infestation. Verbenone is a chemical byproduct released by bark beetles, and it is present in high concentrations while beetles infest a particular tree. Scientists hypothesize that the insects interpret the pheromone as a sign that a host tree already has been colonized, and the beetles, therefore, should seek a different host tree.

Within some lodgepole pine forests, verbenone protected 54 percent of trees with diameters of 13 inches or more.

Citation

Meznarich, Paul; Progar, Robert. 2015. Hidden in Plain sight: Synthetic pheromone misleads beetles, protects trees. Science Findings 170. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 6 p.