Mutualism and Antagonism in Multispecies Interactions: Effects of Fungal Associates on Mountain Pine Beetle Fitness

许多树皮甲虫与真菌密切相关。虽然真菌获得了运输到新的、否则无法到达的寄主树上，但这种相互作用对甲虫的好处一直存在争议。一种范式认为，真菌帮助甲虫杀死树木；然而，许多真菌是非致病的，许多树皮甲虫物种是非侵略性的，只攻击死亡的树木，但仍可能与真菌有关。这个项目的目标是确定树皮甲虫是否从它们的真菌伙伴那里获得营养。通过实验室和野外研究，将确定山松甲虫的两种主要丝状真菌组合对甲虫适合度的影响。还将调查两种真菌伙伴之间的差异，这些差异可能解释授予甲虫的利益的差异。山松甲虫的周期性暴发在北美西部的森林中造成重大的经济损失。如果真菌影响甲虫的适合度，这可能会影响甲虫的种群动态。因此，这项研究不仅有助于了解推动多物种相互作用和塑造生态群落的因素，而且还将有助于更好地了解可能影响一种主要森林害虫种群动态的因素。结果将作为实地考察的一部分向初中生和高中生传播，并在树皮甲虫讲习班期间向公众传播。该项目将支持一名博士生的学位论文研究。

Many bark beetles are closely associated with fungi. While the fungi gain transport to a new and otherwise inaccessible host tree, the benefit of the interaction to the beetle has been debated. One paradigm holds that the fungi help the beetle kill the tree; however, many of the fungi are nonpathogenic and many species of bark beetles are nonaggressive and attack only dead trees, yet may still be associated with fungi. The goal of this project is to determine if bark beetles benefit nutritionally from their fungal associates. Using laboratory and field studies, the effects of the two main filamentous fungal associates of mountain pine beetle on beetle fitness will be determined. Differences between the two fungal associates that may explain variation in benefits conferred to the beetle will also be investigated. Periodic outbreaks of mountain pine beetle cause significant economic losses in western North American forests. If fungal associates affect beetle fitness, this could affect the population dynamics of the insect. Thus, this research will not only contribute to the understanding of factors driving multispecies interactions and shaping ecological communities, but will also lead to a greater understanding of factors that may influence the population dynamics of a major forest pest. Results will be disseminated to middle and high school students as part of field trips and to the public during bark beetle workshops. This project will support the dissertation research of a doctoral student.