DISSERTATION RESEARCH: A mechanistic test of the keystone mutualism hypothesis

本计画将探讨毛毛虫、跳树虫和蚂蚁之间的生态互动如何决定健康的树木。毛虫通过吃树叶来破坏森林树木，而树蝉则通过吸食树汁来捕食树木。树鼩以树液为食的一个重要后果是它们会分泌一种叫做蜜露的含糖溶液。一些森林蚂蚁以蜜露为食。这种关系被称为以食物换保护的互惠共生，因为蚂蚁得到富含碳水化合物的食物，而树跳则得到蚂蚁的保护。在这个项目中，研究人员将研究蚂蚁和树跳之间的这种相互作用如何影响所有参与者，以及结果如何影响森林健康。首先，研究结果将有助于对森林害虫控制的科学理解。第二，该项目将通过培训本科生研究助理，以及通过对大学生、公立学校教师和公众的更广泛的教育利益，促进森林生态学和昆虫学教育。第三，调查人员将与康涅狄格州森林和公园协会（CFPA）合作，该协会为教师和公众提供户外教育项目。更具体地说，这项研究将实验测试几个假设的机制，自上而下的营养作用的蚂蚁，树液，饲养互惠在温带森林社区。该系统包含多个物种的捕食性蚂蚁与食汁昆虫（主要是膜翅目）相互作用。蚂蚁-树液-取食者的互惠作用可能通过增加蚂蚁总丰度（“密度增加假说”）、改变蚂蚁个体的行为（“行为修正假说”）或改变蚂蚁群落结构（“群落转移假说”），对毛虫和植物产生自上而下的营养效应。实验将被用来区分这些假设。本研究系统的社区范围，目前缺乏入侵的蚂蚁物种，是新颖的和重要的，因为它提供了一个机会来测试蚂蚁社区机制的基石互惠效应，以及蚂蚁密度和蚂蚁性状相关的机制，在一个相对完整的生态系统。

This project will investigate how ecological interactions among caterpillars, treehoppers, and ants determine the health trees. Caterpillars damage forest trees by eating leaves and treehoppers feed on trees by sucking sap. An important consequence of sap-feeding by treehoppers is their excretion of a sugary solution called honeydew. Some forest-dwelling ants depend on the honeydew for food. This relationship is called a food-for-protection mutualism because ants receive carbohydrate-rich food, while treehoppers receive protection from predators by the ants. In this project, investigators will study how this interaction between ants and treehoppers affects all participants, and how the outcome impacts forest health.Societal benefits of this project are several-fold. First, results from the research will contribute to the scientific understanding of pest control in forests. Second, the project will contribute to education about forest ecology and entomology through the training of undergraduate research assistants, as well as through broader educational benefits to college students, public school teachers, and members of the public. Third, the investigators will partner with the Connecticut Forest and Park Association (CFPA), which offers outdoor education programs for teachers and members of the public. More specifically, this research will experimentally test several hypothesized mechanisms for top-down trophic effects of ant-sap-feeder mutualisms in a temperate forest community. This system contains multiple species of predatory ants interacting with sap-feeding insects (mainly Membracidae). Ant-sap-feeder mutualisms may trigger top-down trophic effects on caterpillars and plants via increases in total ant abundance (the "density increase hypothesis"), changes in the behavior of individual ants (the "behavioral modification hypothesis"), or changes in ant community structure (the "community shift hypothesis"). Experiments will be used to distinguish among these hypotheses. The community scope of this study system, which currently lacks an invasive ant species, is novel and important because it offers an opportunity to test ant-community mechanisms for keystone mutualism effects as well as ant density- and ant trait-related mechanisms in a relatively intact ecosystem.