Timing of female sexual unreceptivity and male adjustment of copulatory behaviour under competition risk in the wolf spider Schizocosa malitiosa

Abstract

Males can change their copulatory or sperm transfer patterns in response to sperm competition risk. Schizocosa malitiosa performs long copulations, which include two consecutive patterns (Patterns 1 and 2). Virgin females are very sexually receptive, but mated females diminish their receptiveness. Female unreceptivity has been attributed to the action of receptivity-inhibiting substances, mainly transferred during Pattern 1. We tested: (1) if females who mated only with Pattern 1 were immediately unreceptive; (2) male and female behaviours when the copulating couple was exposed to another male. For (1), we interrupted mating when Pattern 1 finished and immediately exposed the female to a second male. For (2), we introduced a second male when the couple was starting (Ei) or finishing copulation (Li). Females were unreceptive immediately after finishing Pattern 1. Males from Ei and Li dismounted and approached the second males. Ei males diminished the frequencies of insertion after perceiving the presence of a second male and dismounted less frequently when copulating with heavy females. The study provides insights about the timing of sexual unreceptivity in S. malitiosa under possibilities of sperm competition, discussing male adjustment of copulatory behaviour in the presence of rival males.