Developmental and lifetime fitness consequences of limb loss in the wolf spider <i>Hogna helluo</i>
The effect of predator hunger on chemically-mediated antipredator responses and survival in the wolf spider Pardosa milvina
ABSTRACT- The wolf spider, Pardosa milvina, exhibits effective antipredator behavior when detecting silk and excreta from a larger co-occurring wolf spider, Hogna helluo. Since the quantity of silk and excreta may vary with the hunger state of the predator, we tested if cues from hungry versus satiated Hogna would influence Pardosa activity level and survival. Pardosa activity was measured on substrates containing chemical cues from 1) a satiated Hogna, 2) Hogna withheld food for 2 weeks, or 3) a control consisting of a blank test container (N = 20/treatment). Pardosa response was recorded on each substrate over a 30-min period using video-tracking equipment. We then measured Pardosa survival in the presence of live hungry and satiated Hogna on each respective substrate treatment in a fully factorial design. Results indicate Hogna cues significantly reduced Pardosa activity level and that Pardosa show significantly less activity in the presence of cues from a hungry Hogna than a satiated one. Predator hunger state and substrate type significantly affected Pardosa survival in the presence of live Hogna. However, cues from hungry vs. satiated Hogna resulted in no difference in Pardosa survival nor was there a significant interaction between Hogna hunger state and substrate type on Pardosa survival. In summary Pardosa can discriminate between hungry versus satiated predators based on silk and excreta cues alone, but differences in behavior as a result of this discrimination did not translate into increased survival in the presence of a live predator.
