1Department of Chemistry, Organic Chemistry, Group of Ecological Chemistry, Royal Institute of Technology, 100 44 Stockholm, Sweden.
2Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden.
Sexual selection theory predicts that the different selection pressures on males and females result in sexual conflict. However, in some instances males and females share a common interest, which could lead to sexual cooperation. In the pierid butterfly Pieris napi the male and the female share a common interest to reduce female harassment by other males after mating. Here we show that P. napi males transfer an antiaphrodisiac to the female at mating, a volatile substance which mated females emit when courted and makes males quickly abandon them. The effect of this antiaphrodisiac is so strong that most males will refrain from mating with virgin females to whom the substans has been artificially applied. In P. napi males also transfer nutrients to females at mating. This increases female fecundity and longevity, and so females benefit from remating. Hence, sexual cooperation gradually turns to conflict. Future research is required to reveal which sex controls the gradual decrease in the substans titer which is necessary to allow mated females to regain attractiveness and remate.