We examined genetic variation of 20-year old, open pollinated (OP), half-sibling lodgepole pine, Pinus contorta, in terms of chemical and physical defenses related to host resistance and tolerance to mountain pine beetle (MPB), Dendroctonus ponderosae (Coleoptera: Curculionidae) and one of its symbiotic fungi, Grosmannia clavigera (=Ophiostoma clavigerum). Our samples were taken from ~900 individuals from 49 OP parent-trees originating from several local and non-local provenances. Families were selected based upon previous work that suggested significant provenance- or stand-level differences in expression of host defensive phenotypic traits. During the summer of 2006, we quantified chemical and physical defensive responses to MPB and G. clavigera. These included growth of lesions and changes in levels of individual terpenoids at two time points following artificial inoculation with the fungus. Our data show heritable differences in terpene makeup pre- and post-induction of MPB-like attack. Changes in lesion length were significantly different between families at the two time intervals after fungal inoculation. Many terpenoids associated with MPB behavior, survival, pheromone production, etc. (e.g., 3-carene, limonene, myrcene, and others) also showed significant differences between families. Levels of some terpenoids increased over time, suggesting some families produce specific compounds that confer more resistance or tolerance to mountain pine beetle.