Male reproductive decision is constrained by sex pheromones produced by females

Male choice has been associated with situations in which there is variation in the quality and reproductive status of females within a population. However, few studies have looked at the ability of males to discriminate between females of different reproductive status when the intensity of the sex pheromone produced by these females is known. Here we investigated the ability of male wolf spiders, Schizocosa malitiosa, to discriminate between silk-born sex pheromones produced by females of different age and mating status using a T-maze system. In particular, we analysed male sexual response between young virgin (YV) and old recently mated (ORM) females, two different reproductive groups that produce similar intensities of sex pheromone. We found that males chose and displayed more courtship behaviour in the silk thread from old virgin females (OV). However, males did not show any preference between silk thread of YV versus ORM females, and there were no differences in courtship behaviours. According to our results, male decision will be constrained by the sex pheromones produced by YV and ORM females. YV females are receptive to mates and do not have any sperm stored, while ORM females are partially reluctant to re-mate and male would share paternity. In other species, females change the composition, or stop the production of the sex pheromone providing information on their reproductive status. However, in this species it seems that females are not emitting clear information about their mating status, which will in turn affect the reproductive decisions of the male.