Effective application of fungi as biological control agents of insects relies on matching fungal traits to ecological conditions. In this study isolates of Beauveria bassiana from sources in the intermountain west were tested for their ability to grow, persist, and reduce survival of spruce beetle, Dendroctonus rufipennis, under a suite of environmental conditions. Growth of each isolate was measured during exposure to a range of temperatures, ultraviolet light intensities, relative humidities, nutrients, and two previously unstudied environmental factors unique to the spruce beetle study system – an array of Engelmann spruce, Picea engelmannii, tree defense chemicals and isolates of a spruce beetle symbiotic fungus, Leptographium abietinum. An understanding of environmental factors influencing Beauveria bassiana growth and tradeoffs between environmental tolerance and pathogenicity can help practitioners match fungal traits to environmental conditions for the purposes of maximizing efficacy in field application. Using functional trait data gathered through evaluating Beauveria bassiana in the spruce beetle study system, this presentation will address three questions: (1) is there evidence for phenotypic variation between Beauveria bassiana isolated from sources in the intermountain west? (2) do Beauveria bassiana isolates vary in their ability reduce spruce beetle survival? (3) do tradeoffs exist between environmental tolerance and pathogenicity?
Results/Conclusions
Two statistically distinct hierarchical cluster groups emerged based on the ability of isolates to tolerate spruce tree defense chemicals. There was evidence for phenotypic variation between Beauveria bassiana isolates when exposed to 15 °C, 30 °C, 0.1% α-pinene, and 1% 3-carene. Median survival time of spruce beetles ranged from 6 to 10 days when introduced to isolates of Beauveria bassiana, leading to a statistically significant difference in the ability of Beauveria bassiana isolates to reduce spruce beetle survival. Finally, the possibility for tradeoffs between environmental tolerance and pathogenicity remains as more environmental characteristics are still to be examined.