Dissertation Research: Factors Controlling Larval Survival in the Odonate, Aeshna juncea

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The factors that control the distribution and abundance of animal populations are of fundamental interest to biologists. The goal of this project is to determine the factors controlling a population of dragonfly larvae inhabiting rocky shorelines of Lake Superior. The approach employs a variety of techniques to test hypotheses seeking to explain the distribution and abundance of the dragonflies. The small size and clear water of the pools facilitate censusing population sizes and observing behavioral interactions with minimal disturbance to the community. In addition, the rocky shoreline contains a large number of similar pools, so it is possible to perform well-replicated field experiments without erecting cages or pens. Several experiments address the hypotheses that populations are limited by competition for food or cannibalism between size classes. The temperatures of many pools will be continuously measured to determine if dragonflies are excluded from some pools by extreme conditions in summer or winter. Adult dragonflies will be monitored to determine if patterns of larval distribution are produced by oviposition preferences. The results of this project will help generate a clearer picture of what controls natural insect populations; such information is necessary for designing appropriate programs for pest management and biological control.