Chemically Mediated Sexual Attraction of Male Cyclocephala lurida (Coleoptera: Scarabaeidae) and Other Scarabaeid Beetles to Immature Stages

Abstract

Adult females of the southern masked chafer, Cyclocephala lurida Bland, produce a volatile sex pheromone that attracts conspecific males. Previously we documented that extracts of 3rd-instar Cyclocephala spp. grubs contain one or more compounds that attract males and stimulate copulatory attempts when these males arrive at the source of the odor. Attraction of males to larvae appears to be undocumented for any other insect species. We examined developmental expression of the production of this attractant within Cyclocephala spp., and evaluated hexane extracts of other species of scarabaeid grubs for attractiveness to C. lurida or conspecifics. We found that the attractant is not limited to the postoverwintering last instar, but rather is present in all larval stages and in male and female pupae. Extracts of Cyclocephala spp. grubs also attracted males of the northern masked chafer, Cyclocephala borealis Arrow. Hexane extracts of 3rd instars of Japanese beetles, Popillia japonica Newman, and green June beetles, Cotinis nitida L., were not attractive to male C. lurida , indicating that there is some phylogenetic specificity to this unusual production of a sex-specific attractant. Third instars of C. nitida do not attract conspecific males. Studies of male attraction to conspecific immature stages in Cyclocephala spp. and other Scarabaeidae may provide insights into the evolutionary origins of chemical communication systems.