Do the amount of sex pheromone and frequency of calling behavior in females affect the mate-searching behavior of males in Dasylepida ishigakiensis (Coleoptera: Scarabaeidae)?

Abstract

The white grub beetle Dasylepida ishigakiensis Niijima et Kinoshita (Coleoptera: Scarabaeidae) is a serious sugarcane pest on the Miyako Islands, Okinawa, Japan. Because this beetle stays underground for most of its lifetime, mating disruption using a synthetic sex pheromone has been suggested as a promising control measure. The amount of pheromone (2-butanol) released by the females is known to decrease drastically as they repeat calling each day. In this study, we determined the response of males to different concentrations of (R)-2-butanol, both in the laboratory and in the field. Males showed typical pre-mating behaviors and they were attracted to (R)-2-butanol even at a concentration 1/100 of the amount typically emitted by a female during the 1st period of calling. We examined whether female attractiveness to males was reduced with the frequency of calling, by counting the number of males attracted to females that had called during zero to five periods beforehand. Our results indicated that a high level of female attractiveness was maintained even after three periods of calling. Based on these findings, we propose that releasing synthetic sex pheromone shortly before the start of the mating season and into the late mating season may be optimal for disrupting the mating of this beetle.