The significance of multiple mating and male substance transferred to females at mating in the white grub beetle, Dasylepida ishigakiensis (Coleoptera: Scarabaeidae)

Males of the white grub beetle, Dasylepida ishigakiensis Niijima et Kinoshita, transfer a large amount of a colloidal substance to females during mating. In this study we investigated the effect of the male substance on the reproductive performance of mated females and the significance of multiple mating of this beetle. Females artificially separated from the males 5 min after the start of mating produced fewer eggs than those separated after 30 min or those that were undisturbed and separated spontaneously, suggesting that the male substance is used as a nutrient for egg production by the females. When females were allowed to mate with 1-4 males, multiple mating had no clear effect on reproductive performance. The amount of male substance stored in the bursa copulatrix (BC) was not significantly increased by a second mating. The functions of multiple mating of this species may be to provide a chance for females to obtain sufficient amounts of male substance when the first male to mate has only small amounts of this substance, and to increase the genetic heterogeneity of the progeny. The presence of a serine proteinase and its possible involvement in the dynamics of the BC contents are reported.