Structure of Plant-Arthropod Associations: Impact of Herbivores on Community Composition and Host Performance

研究黄花取食昆虫在演替过程中对单株茎的生长和繁殖以及对野外群落组成的影响。将在新开垦的土地上抑制昆虫种群，以确定昆虫取食是否会影响在这些土地上建立的植物物种。为了补充这种整体方法，将对两种古老的田间群落成员——黄花和草莓进行更详细的实验，以评估食草动物在调解两者之间的竞争结果中所起的作用。第二个目的是详细研究不同类型的食草动物取食损害对单株菊花茎适合度的影响。以各种方式模拟草食损害的实验将有助于研究昆虫损害如何破坏植物体内碳水化合物来源和吸收之间的平衡。此外，由于在不同肥力水平下生长的黄花会吸引不同的食草动物，因此将进行试验，以评估土壤肥力和昆虫取食方式对植物适合度的综合影响。对以菊科植物为食的几种昆虫种群的时空变化的长期研究将继续进行。为了进一步了解不同地点的动物群结构和食草动物负荷的质量，将进行旨在确定几种昆虫寻找寄主能力的实验。通过确定实验条件自然发生的频率，这些数据为解释更集中的实验提供了一个背景。它们也为建立关于菊花昆虫动物群结构和物种间相互作用的新假设奠定了基础。

The impact of goldenrod-feeding insects on the growth and reproduction of individual stems and on field community composition during the course of succession will be studied. Insect populations will be surpressed in plots of newly cleared ground to determine whether feeding by insects affects which plant species become established in these plots. To supplement this holistic approach, more detailed experiments will be performed on two members of the old field community, goldenrod and strawberry, to assess the role herbivores play in mediating the competitive outcome between the two. A second objective is to examine in detail the effect of different types of herbivore feeding damage on the fitness of individual goldenrod stems. Experiments in which herbivore damage is simulated in various ways will allow the investigation of how insect damage disrupts the balance between carbohydrate sources and sinks within the plant. In addition, because different herbivores are attracted to goldenrods growing at different fertility levels, experiments will be conducted to assess the combined effect of soil fertility and insect feeding style on plant fitness. Long-term studies of the spatial and temporal variation in the populations of several insect species that feed on goldenrod will be continued. To gain further insight into the structure of the fauna and the quality of the herbivore load at our various sites, experiments designed to determine the host finding abilities of several insect species will be conducted. These data provide a context for interpreting the more focused experiments by allowing the frequency with which our experimental conditions occur naturally to be determined. They also form the basis for building new hypotheses about the structure of the insect fauna of goldenrods and the interactions between species.