Monday, December 11, 2006

Effects of different cucumber plant architectures on the foraging efficiency of the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae)

Lessando Moreira Gontijo,, James Nechols,, and David C. Margolies, Kansas State University, 123 W. Waters Hall, Kansas State University, Manhattan, KS

The ability of predators to search for, find, and attack prey is considered to be one of the most important attributes of an effective natural enemy. Many intrinsic and environmental factors affect predator foraging efficiency. However, one of the most interesting and influential factors is the host plant on which herbivorous prey are found. Plants may have direct effects on predator movement as well as indirect effects by affecting prey distribution, abundance and behavior. Recent evidence suggests that plant architecture plays an important role in tritrophic interactions. In this work we investigated the effects of different cucumber plant architectures on the foraging efficiency of the predatory mite, Phytoseiulus persimilis Athias-Henriot; by measuring its prey-finding time. To do this assessment we quantified the amount of time spent by P. persimilis to encounter a prey patch of Tetranychus urticae Koch, when foraging on different cucumber plant architectures. We tested two different prey distributions on two different plant architectures which presented approximately constant total plant surface area. We observed that prey distribution had an effect on prey-finding time when P. persimilis was foraging on the complex plant architecture, whereas it had no effect when foraging on simpler plant architecture. P. persimilis required longer time to encounter a prey patch on more complex plant architectures when the prey was located on a single leaf. There were no significant differences in prey-finding time on plants comprised of complex vs. simple architectures when prey were distributed evenly within the canopy of complex plant architecture.

Species 1: Acari Phytoseiidae Phytoseiulus persimilis
Species 2: Acari Tetranychidae Tetranychus urticae