QEIB: Predicting the Effects of Diffusion-limitation in a Predator-prey System

Ohio University, Athens OH

Investigators

Abstract

Ecological theories used to predict species interactions typically do not take into account the effects of small-scale spatial structure. It is assumed that the success of predators, like ladybugs, is more or less the same whether they are found on corn plants or pea plants. This assumption does not fit our commonsense experience of the world. It is harder to move through some environments than others because of spatial complexity, and this limitation of mobility should affect species interactions such as the predator-prey relationship. As environments become more complex the encounter rate of predators and prey should decrease. Therefore, in the same way that chemical reactions slow down in complex media (i.e., they are "diffusion-limited" because of the slow movement of molecules in complex spaces), so to we expect a reduction in predation success on plants with complex shapes. In the proposed research, models based on this expectation will be developed and tested using a predator-prey system that is important in agriculture. Naturally occurring pea mutants have been widely adopted for commercial use, however the more complex shape of these peas may alter the efficacy of beneficial insects. Using pea mutants with differing degrees of leaf complexity, the author will examine the predation success of the ladybug Harmonia axyridis, a commonly used beneficial insect, on pea aphids in laboratory and greenhouse conditions. By using this experimental system she will simultaneously test a new ecological theory and evaluate of the effects of plant morphology on biological control programs.