Sexual cooperation and conflict in butterflies: a male-transferred anti-aphrodisiac reduces harassment of recently mated females

Sexual selection theory predicts that the different selection pressures on males and females result in sexual conflict. However, in some instances mal es and females share a common interest which could lead to sexual cooperati on. In the pierid butterfly Pieris napi the male and the recently mated fem ale share a common interest in reducing female harassment by other males so on after mating. Here we show that P. napi males transfer an anti-aphrodisi ac to the female at mating, methyl-salicylate (MeS), which is a volatile su bstance which mated females emit when courted and which makes males quickly abandon them. A C-13-labelling experiment demonstrated that only males syn thesize MeS. The effect of this antiaphrodisiac is so strong that most male s will refrain from mating with virgin females to whom MeS has been artific ially applied. In P. napi, males also transfer nutrients to females at mati ng. This increases female fecundity and longevity and so females benefit fr om remating. Hence, sexual cooperation gradually turns to conflict. Future research is required to reveal which sex controls the gradual decrease in t he MeS titre which is necessary for allowing mated females to regain attrac tiveness and remate.