The Role of Antagonism, Commensalism, and Mutualism in Bark Beetle Communities

树皮甲虫群落中对抗、共生和共生的作用Ayres，Matthew P.Dart茅斯学院物种间的积极联系(共生和共生)，虽然在自然界中普遍存在，但并没有很好地整合到群落生态学的理论结构中。这个项目将研究树皮甲虫(Dendroctonus)之间的相互作用，以测试互惠共生对种群和社区的影响。南方松毛虫与两种真菌有一种特有的互惠共生关系。这些真菌由成虫传播，并在产卵期间接种在松树的韧皮部内。甲虫幼虫以韧皮部内的真菌为食。幼虫死亡的一个常见原因是来自蓝藻真菌的竞争导致真菌生长不良。这种真菌也有很强的互惠性，但与螨类(Tarsonemus)有很强的互惠关系，后者在树木之间运输真菌的子囊孢子，并以树木韧皮部内的这种真菌为食。反过来，这些螨虫又被甲虫传播。这些系统特性被假设为影响整个群落，并影响甲虫暴发种群动态和松树死亡，这是美国东南部森林干扰的主要来源。对这种甲虫-螨类-真菌群落的研究还发现，甲虫和甲虫对温度变化的生长反应存在显著差异，这表明气候的季节性和区域性变化应该对群落进行调节。这项工作还将测试物种之间的这些差异是否会导致完整群落的可预测反应。该项目的结果将对阐明互惠关系在群落生态学和种群动态中的作用以及这些相互作用对温度的依赖具有科学价值。对影响昆虫暴发的过程的新理解将与森林管理相关，并有助于评估气候变化和外来物种引进对森林的风险。拟议的活动还将对青年科学家的培训作出贡献，从而产生更广泛的有益影响。

The Role of Antagonism, Commensalism, and Mutualism in Bark Beetle CommunitiesAyres, Matthew P.Dartmouth CollegePositive associations between species (mutualisms and commensalisms), although ubiquitous in nature, are not well integrated within the theoretical structure of community ecology. This project will study interactions involving bark beetles (Dendroctonus) to test the consequences of mutualisms for populations and communities. The southern pine beetle has an obligate mutualism with two species of fungi. The fungi are transported by adult beetles and inoculated within the phloem of the pine trees during egg laying. The beetle larval feeds upon the fungi within the phloem. A common cause of larval mortality is poor growth of the fungi due to competition from the bluestain fungus. This fungus also has a strong mutualism but with mites (Tarsonemus), which transport the fungus ascospores between trees, and feed upon this fungus within the tree phloem. The mites, in turn, are transported by the beetles. These system properties are hypothesized to impact the entire community and influence the outbreak population dynamics of beetles and death of pines, which is a dominant source of disturbance in forests of the southeastern U.S. Studies of this beetle-mite-fungus community have also revealed marked differences between mites and beetles in their growth response to temperature change, which suggests that seasonal and regional variation in climate should modulate the community. This work will also test whether these differences among species lead to predictable responses of the intact community. Results of this project will have scientific value in clarifying the role of mutualisms in community ecology and population dynamics and the dependence of these interactions on temperature. New understanding of the processes that influence insect outbreaks will have relevance to forest management, and aid in assessing risks to forests from climate change and introductions of exotic species. Proposed activities will also have broader beneficial impacts by contributing to the training of young scientists.