A comparison of the effect of pulsed and continuous predation risk on behavior and body condition in the wolf spider Pardosa milvina.
The wolf spider, Pardosa milvina, shows a variety of antipredator responses in the presence of silk and excreta from a larger predator, Hogna helluo. We examined the relative influence of duration of predator cue exposure and quality of predator cues on female P. milvina behavior and body condition. We measured the frequency in which Pardosa females engage in antipredator behavior (vertical movement) under different predator exposure regimens over an 8-d period while having constant access to prey. We also recorded changes in female body condition during this time interval (cephalothorax/abdomen ratio). Six experimental treatments were used (n=20/treatment) :1) constant exposure to peat moss previously exposed to an adult female Hogna for three days, 2) as in treatment 1, except the substrate was renewed every three days with fresh predator cues, and 3) exposure to Hogna cues every two days followed by two days without predator cues. For each of the three predator exposure treatments, we had three corresponding treatments without predator cues to control for the effects of disturbance and measurement. We found significant differences in antipredator behavior between cued and uncued treatments. The magnitude of Pardosa responses tended to drop when predator cues were not renewed. However, Pardosa under pulsed predation risk behaved no differently than individuals under constant risk. Predation risk significantly impacted body condition as well. Spiders in all cued treatments had significantly poorer body condition than those in control treatments.