Chemical communication in Schizocosa malitiosa: evidence of a female contact sex pheromone and persistence in the field.

Mate finding in many spider species is mediated, at least in part, by chemical cues. Although few have been characterized, most spider sex pheromones seem to be associated with the silk threads of adult females, attracting and/or triggering sexual behaviors in males. Schizocosa malitiosa (Araneae: Lycosidae) is a wolf spider common in dry environments in Southern Uruguay. Here, we report evidence for the occurrence of a female sex pheromone in the silk of virgin S. malitiosa females. The pheromone elicits typical courtship displays by conspecific males (palpal drumming and leg shaking), when it is applied to an artificial substrate. We also showed that this pheromone is quickly inactivated under field conditions, possibly due to the effect of dew, and that it is readily extracted from the silk by water, which renders the silk threads inactive. Preliminary chemical analyses by mass spectrometry suggest that the pheromone is a low molecular weight, highly oxygenated polar compound, present in a high concentration only in older virgin females. Quick inactivation in the field of the pheromone would allow males to discriminate between recent and old cues, thus facilitating mate searching and sexual meeting, by preventing males from following old cues for wandering females that could be distant in space and/or time.