Many animals must balance the need to find food against the risks of being eaten themselves, by predators, when feeding. As a result, the best food source, or host plant, for an herbivore may fluctuate, because both plant nutritional quality and the intensity of predation change in time and space. The goal of this project is to assess the preference and performance of a common butterfly, the Silver-spotted Skipper, on an array of plant species that are currently used by its caterpillars as food plants. The researchers will construct an experimental garden of these common plants and measure differences in survival, growth, and reproduction of juvenile and adult skippers among plants over time. These data will be used to construct an ecological model predicting food plant effects on local populations of skippers. In addition, behavioral observations of predation on caterpillars in the field will be made to compare the activity and composition of the natural enemy communities found on different food plants. In combination, these approaches will provide a uniquely comprehensive investigation of temporal variation in plant-based and enemy-based measures of success in a common herbivore.
A better understanding of the factors determining the diets of plant-feeding insects will contribute significantly to the design of effective biological control strategies to minimize economic damage caused by insect pests. Because the herbivore under study feeds on several invasive plants, the results of this research will be useful to land managers charged with protecting the integrity of natural communities. Extensive educational outreach to K-5 schools in the Washington, DC, area will provide both students and teachers access to hands-on projects exposing them to ecological principles, the practice of careful observation, and the scientific method. Teachers will learn to use local insects in classroom exercises that support science curricula.
