Monoterpene emissions from lodgepole and jack pine bark inoculated with mountain pine beetle-associated fungi

Relative monoterpene levels were analyzed from bark samples of lodgepole pine, jack pine, and their hybrids inoculated with mountain pine beetle (MPB)-associated fungi (Leptographium longiclavatum, Grosmannia clavigera, and Ophiostoma montium). Lodgepole pine showed the largest changes in relative emissions as a result of fungal inoculation. The relative emission of -phellandrene increased with fungal inoculation, making it the most abundant monoterpene for inoculated samples. Relative emissions of limonene and -pinene decreased in inoculated lodgepole pine. Lodgepole (5.6) and jack (146) pine differed in the ratio of -pinene to myrcene; two monoterpenes involved in pheromone synthesis by the MPB. These differences may contribute to the attractiveness of the two species as hosts for MPB; with jack pine potentially less attractive than lodgepole pine. Fungal inoculation reduced -pinene:myrcene ratios in lodgepole pine, which suggests one possible mechanism by which the fungi benefit the beetle.