Interactions Between Host Trees, Bacteria, and Fungi: Impacts on Mountain Pine Beetle (Dendroctonus ponderosae) Reproduction

Abstract

Warming winter trends due to climate change have allowed for a range expansion of the mountain pine beetle, and the beetle now threatens Canada’s economically and ecologically important jack pine forests. The beetle’s success in jack pine trees will depend upon successful colonization of the host by the beetle and its bacterial and fungal associates. The objectives of this thesis were to determine how tree bacteria-fungi interactions impact mountain pine beetle reproduction and whether these interactions hinder beetle invasion of jack pines. Results from monitoring beetle reproduction in the presence of various bacterium fungus combinations in lodgepole, jack, and hybrid pines show that the roles of the bacteria and fungi are mediated by the host tree, and the importance of these microorganisms is dependent upon the biological activities of the beetles under the bark. Further, interactions between the beetle and these microbes are not limiting factors in the invasion of jack pine.