The Effects of Resource Quality, Predation Risk, and Density on the Development of Ageneotettix deorum (Orthoptera: Acrididae)

Competition, predation, and resource quality interact to limit and regulate the dynamics of arthropod herbivores. Several studies have observed the effects of these factors on the survival and limitation of grasshoppers. I am primarily interested in how these factors may interact and affect the development of grasshoppers. To investigate these effects I conducted field experiments during the summer of 2001 at Arapaho Prairie in Western Nebraska. Naturally occurring Lycosid spiders were used as the predators in these experiments. Resources were enhanced through the application of a fertilizer treatment. Cages were stocked with variable densities of Ageneotettix deorum nymphs. Response variables measured until the completion of nymphal development were the rate of development and the length of the hind femur. In addition to these measured responses, I also tracked the survival of grasshoppers through development and into adulthood.

Preliminary analysis of results suggest predation risk and resource quality significantly affect the development of these grasshoppers. It also appears that density may play an important role in determining the relative impacts of these factors to the development of these insects. I plan to investigate the effects of these factors on fecundity and potential trade-offs that might exist between reproduction and nymphal development in the near future through ovariole analysis of surviving females using standard techniques. Using the combination of these results I will refine my experimental design if necessary and repeat the experiment next summer.

Bradford J. Danner
205B Manter Hall
Dept. of Biological Sciences
University of Nebraska- Lincoln
Lincoln, NE 68588-0118

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