The secondary compounds of pines (Pinus) can strongly affect the physiology, ecology and behaviour of bark beetles (Coleoptera: Curculionidae, Scolytinae) that feed on host subcortical tissues. Jack pine (Pinus banksiana) has a wide distribution range in North America and thus variations in its secondary compounds, particularly monoterpenes, could affect the host expansion of mountain pine beetle (Dendroctonus ponderosae), which has recently attacked jack pine as a novel host and expanded its

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... nge into the boreal forest. I analyzed variations in monoterpene composition of jack pine foliage and phloem from natural and provenance stands representing populations from Alberta to the Atlantic coast. Additionally, the effects of variations in phloem monoterpene composition on pheromone production by mountain pine beetle were analyzed. Throughout its range, jack pine foliage monoterpenes were classified into three chemotypes characterized by high proportions of the monoterpenes α-pinene, β-pinene, or limonene. Expression of these chemotypes was controlled by both genetic and environmental factors and individual monoterpenes were correlated with climatic variables differently. Conversely, phloem monoterpenes were classified into groups characterized by high amounts of the monoterpenes (+)-α-pinene, 3-carene or no notably high individual compound and beetle aggregation and anti-aggregation pheromone production varied with these groups. Furthermore, pheromone production also varied between provinces, with the most aggregation pheromone produced in trees from Manitoba and Quebec. These results indicate that pheromone production by D. ponderosae will vary with host chemistry but remain a viable and important aspect of its survival and persistence in the boreal forest. iii