Effects of climate change on interactions between host trees and beetle-fungal symbiont complex

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Mountain pine beetle (MPB) killed millions of trees, largely lodgepole pine in western Canada. Furthermore, the beetle expanded its range to higher altitudes and latitudes. However, it is unknown if lodgepole pines differ in their vulnerability to beetles along altitude and latitude gradients. In my application, I propose to test four objectives targeting four aspects of MPB invasion processes in the naïve lodgepole pine forests, with particular emphasis on the long-term consequences of climate change and kinship recognition on plant defenses and related (carbohydrates) chemicals. First objective will investigate if altitude and latitude gradients affect vulnerability of pines to MPB through altering concentration of chemical defenses and carbohydrates of pine trees. Host vulnerability to MPB will be confirmed in laboratory bioassays. Second objective will determine if altitude and latitude gradients influence nitrogen and ergosterol concentrations of pines and fungal symbionts of MPB. Third objective will determine if altitude and latitude gradients alter the influence of environment and tree genetics on chemical defenses and carbohydrates of pines. The final objective will test if kinship affects plant-to-plant communication via volatile chemicals emitted by trees in response to colonization by MPB in a greenhouse. Information resulting from these studies will be important for both basic and applied understanding of insect invasions in naïve forests. The first three objectives will improve climate change adaptation strategies to invasive insect species. Given that MPB has invaded areas that were historically climatically unsuitable to its survival, the proposed research on the vulnerability of pine trees across the altitudinal and latitudinal gradients is timely and needed for development of policies to manage MPB outbreaks in western Canada. For instance, assisted tree migration is a common climate change adaptation strategy in forestry; however it does not incorporate the effects of climate change on tree vulnerability to pests. Thus, the outcome of this study can be critical for climate change adaptation strategies in Canada and beyond. The planned studies will also determine if environment has a stronger impact on chemical defenses of pines along altitude than latitude gradients; this finding will likely influence climate adaptation and assisted migration programs across Canada and elsewhere. Furthermore, understanding the effects of climate change on microbial symbionts will give us a better knowledge about how they may affect the range expansion of invasive species in this and other regions. Finally, understanding the ecological and evolutionary roles of plant VOCs in tree-to-tree communication may not only improve our understanding of tree survival during insect and pathogen outbreaks but also create opportunities for active management practices such as `priming' or sensitizing induced tree defenses before insect attacks.