Not as “simplex” as that: Understanding the ecological role of frontalin in relation to Dendroctonus simplex LeConte

Eastern larch beetle, Dendroctonus simplex LeConte, is a native, historically non-aggressive bark beetle. Its range is sympatric to its host, Larix laricina; a tree ecologically important to ecosystem services such as habitat provision, carbon sequestration, and water filtration.

While historically eastern larch beetle populations experience small, sporadic outbreaks following predisposing factors, in Minnesota, this has shifted to landscape-level outbreaks. Shifts in population levels are likely driven by warmer summers and extended growing seasons facilitating a bivoltine lifecycle. Since the year 2000, the eastern larch beetle outbreak has impacted approximately 70% of tamarack cover type within the state of Minnesota. Despite the prominence of this insect in recent years, there remain gaps in our understanding of its chemical ecology. For example, while frontalin is produced by female beetles when tunneling into trees, its ecological functions have not been thoroughly elucidated. We isolated pheromones from females tunneling into host tissue, conducted assays to study responses of walking beetles to frontalin volatiles in the laboratory, and conducted field trapping experiments to examine dose-response curves for attraction when combined with seudenol.