Mountain Pine Beetle
The current epidemic of mountain pine beetle (MPB, Dendroctonus ponderosae) in British Columbia is the largest bark beetle outbreak in recorded history. Warmer winters – an indicator of climate change – and other factors have enabled beetle invasion into regions where it has not been previously recorded. Newly developed genomic resources for MPB provide a resource for better understanding the spread of MPB, as well as other related bark beetles and weevils that include many of the most destructive pests of forests and agricultural crops in the world.
Larval mortality during the winter is extremely important in determining the dynamics and spread of MPB populations. After successfully emerging from their brood tree, adult MPB search for suitable new trees for reproduction, guided by host tree volatiles and the aggregation pheromones of other beetles. Upon joining an aggregation, the beetles (with the aid of the symbiotic fungi that they carry with them) attempt to colonize the pine tree, which actively defends itself with toxic secondary metabolites (terpenoids and phenolics). The ability of the beetle to tolerate tree defenses and even use the host tree terpenoids in pheromone production plays a large role in the successful reproduction of the invading beetle/fungus complex.
A genome-based understanding of the molecular physiology of olfaction, detoxification, pheromone biosynthesis, and over-wintering physiology will provide the foundation for a better understanding of beetle population diversity and spread, and will thus lead to better-informed models to predict MPB infestations.