Terpene composition of lodgepole and jack pine and its relationship to the success of the mountain pine beetle

Host tree defensive ability in new geographic regions and in different species could play a role in the success of mountain pine beetle. Constitutive and induced terpene-based defenses were tested in lodgepole and jack pine. Sampled lodgepole pines were assessed for number of beetle attacks. Trees with higher historical exposure to the insect had lower levels of defensive terpenes and lower attack densities, which may be explained by reduced apparency. Significant differences existed in constitutive and induced levels of terpenes between species; higher levels of most terpenes were found in lodgepole pine. Jack pine had higher levels of alpha-pinene, which has implications for beetle success as this terpene is involved in pheromone biosynthesis. This insect faces different terpene-based chemical defenses in host species that it encounters in new geographic ranges and these differences should be taken into account in management plans across large geographic ranges and multiple host species.