Evidence that mating plug is related to null female mating activity in the scorpion Vaejovis punctatus

Abstract

We document a case in which the mating plug of the scorpion Vaejovis punctatus seems correlated with a reduction in female sexual receptivity. We used two morphological and behavioral analyses. The mating plug was dissected and described from both males and females: it bears a set of spines and two enlarged terminations which possibly allow anchoring to the female inside and impede removal. Behavioral observations support this view: after sperm transfer ended, the female tried to remove the plug by rubbing the ventral side of her body using her second and third pair of legs. This pattern was also performed after mate separation. All females seemed unable to displace the plug and rejected male mating attempts. The mating plug suffered a progressive degradation into the female. This degradation was completed 2 or 3 mo prior to parturition, so that the plug did not seem a barrier for the emergence of embryos. Furthermore, females bearing mating plugs in different degradation stages did not accept another mating during the reproductive season, and sexual acceptance was reinitiated only after parturition. The mating plug therefore seems to correlate with a lost in mating activity. The comparison of this structure with that of other scorpion species allows us to hypothesize a sexual coevolutionary scenario in which the effectiveness of the plug to inhibit female remating may lie at the center of such interaction.