Information content of female chemical signals in the wolf spider, Schizocosa ocreata: male discrimination of reproductive state and receptivity

Abstract

Fine-scale information content of chemical signals has been widely studied in several vertebrate taxa and in social and economically important invertebrate taxa but remains poorly understood for many invertebrate predators such as spiders. Chemical signals (e.g. pheromones) associated with spider silk may convey information about species identity, sex, age and/or reproductive status of a female to male receivers. In the wolf spider Schizocosa ocreata (Hentz), females are cryptic within the leaf-litter habitat, are potentially aggressive and/or cannibalistic depending on reproductive status and age, and do not appear to communicate their status to males using seismic or visual signals. Hence, males are expected to exploit female chemical signals to discriminate among potential mates. We used behavioural assays to determine whether male S. ocreata can discriminate potentially receptive mates using cues associated with female silk. Males were presented with silk from females that varied in reproductive status and/or potential receptivity. Males showed significantly more and longer bouts of chemosensory and courtship behaviours, with significantly reduced latency, on the silk of adult, unmated female spiders than on any other stimulus treatment, including the silk of subadult and mated females. Additionally, male S. ocreata responded less to the silk cues of females that were within 1 week prior to maturity and the silk of females that had recently moulted (females up to 1 week old). This is significant, as females show increased aggression to males during their first week of adulthood and after mating. Thus, males clearly possess the ability to assess reproductive status as well as age-related potential receptivity of conspecific females based on cues associated with silk.