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

在演替过程中，将研究取食黄花的昆虫对个体茎的生长和繁殖以及对田间群落组成的影响。在新开垦的地块中，昆虫种群将受到抑制，以确定昆虫的取食是否会影响这些地块中形成的植物物种。为了补充这一整体方法，将在旧田野群落的两个成员--黄花和草莓上进行更详细的实验，以评估草食动物在调节两者之间的竞争结果中所起的作用。第二个目标是详细研究不同类型的食草动物取食损害对个体黄花茎适合性的影响。以各种方式模拟食草动物损害的实验将允许调查昆虫损害如何破坏植物内碳水化合物来源和汇之间的平衡。此外，由于不同的食草动物会被生长在不同肥力水平的黄花所吸引，因此将进行实验，以评估土壤肥力和昆虫取食方式对植物适合性的综合影响。将继续对以黄花为食的几种昆虫种群的空间和时间变化进行长期研究。为了进一步了解我们不同地点的动物群结构和食草动物负载的质量，将进行旨在确定几种昆虫寻找宿主能力的实验。这些数据允许我们的实验条件自然发生的频率被确定，从而为解释更有针对性的实验提供了背景。它们也构成了建立关于黄花昆虫区系结构和物种间相互作用的新假说的基础。

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.