Evolutionary correlation between male substances and female remating frequency in a seed beetle

An evolutionary correlation between the effects of male seminal substances that reduce female sexual receptivity and female remating frequency was found among strains of the adzuki bean beetle, Callosobruchus chinensis. Variation in female remating frequency had been also previously documented in this species, together with the identification in males of low- and high-molecular weight substances that exhibited quick- and slow-acting effects on female sexual receptivity. Here, we examined the differences in the effects of both substances on female sexual receptivity between strains with high and low remating frequencies. We found that the female response to the quick-acting substances differed. Moreover, not only female response to the slow-acting substances but also the male effect of these substances differed between strains. In remating experiments, a difference in female response to mating was found, but no difference was found in the effect of males between strains. Thus, male sexual receptivity-inhibiting substances are one of the reasons for the difference in female remating frequency between the 2 strains. Next, the relationship between the effect of male substances on female sexual receptivity and female remating frequency was examined among multiple strains. Correlations between the effect of mating and male substances were found for both molecular weight classes of male substances. These results suggest that both female response to male substances and the effect of male receptivity-inhibiting substances reflect variations in female remating frequency among strains.