Mechanisms by Which Root Disease Induced Changes in Ponderosa Pine Physiology Effect Bark Beetle Behavior

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9630934 Wood The physiological responses of trees to root pathogens, and the resulting effects on plant-feeding insect behavior are poorly understood. The studies outlined here aim to characterize: 1) the biochemical changes in ponderosa pine (Pinus ponderosa) in response to annosus root disease (Heterobasidion annosum), emphasizing induced changes in parts of the tree not infected by the fungus (i.e., systematic induction). Preliminary evidence indicates that a systemic response occurs, especially with respect to stilbenes, and that these substances are associated with development of disease symptoms. Greenhouse and field experiments will be carried out to further characterize this unexpected and novel phenomenon in conifers. 2) the influence of compounds produced by the host in response to the root pathogen (including stilbenes and ethylene, among others), and by the pathogen itself, on bark beetle behavior mountain pine beetle (Dendroctonus ponderosae) and the western pine beetle (D. brevicomis) (Coleoptera: Scolytidae) . The role of compounds produced during the physiological response of the host tree to the root pathogen as attractants and/or feeding stimulants will be determined in the laboratory and the field, in order to better understand how these bark beetles detect suitable host tissue for colonization. This work will significantly advance our knowledge of fundamental ecophysiological interactions, integrating partners as diverse as fungal pathogens, forest trees, and associated bark beetles. A greater knowledge of this three way interaction will also ultimately lead to a greater understanding of other plant/herbivore systems and provide the basis for elucidating the physiological mechanisms of host resistance to herbivores. Hence, this investigation may also result in modified strategies for forest disease and bark beetle man agement, based on better knowledge of tree decline and the role of host physiopathology in bark beetle colonization.