Behavioral and ecophysiological responses of a generalist predator to single- and mixed-species diets of different quality

Prey of different quality can be distinguished by their effects on fitness parameters (e.g., survival, growth, development) of the predator. This pape r describes a series of experiments with wolf spiders, Schizocosa sp., desi gned to analyze the behavioral and physiological mechanisms by which these effects are brought about. Schizocosa responded to prey of inferior quality by developing an aversion. The number of prey encounters needed for the av ersion to develop depended on the prey type and the quality of alternative prey available. As expected, fewer low-quality prey were accepted if prey o f higher quality were available; however, acceptance was also reduced if al ternative prey were of even lower quality. An aversion disappeared within a few hours to about 1 day. Consumption by Schizocosa of even small amounts of some "toxic" prey species reduced growth by inhibiting feeding rate and impairing utilization of food derived from prey of higher quality. These re sults have implications for understanding the interactions of generalist pr edators in community food webs.