Extrinsic and Intrinsic Factors Influencing the Emerging and Burrowing Behaviors of Reproductively Active Adults of the White Grub Beetle, Dasylepida ishigakiensis

Abstract

The subtropical scarab beetle, Dasylepida ishigakiensis, has a two-year life cycle. This study showed the time of adult emergence from the soil relative to the time of dusk and the presence of the female sex pheromone. Beetles collected on Miyako Island were transported to Tsukuba where they were immediately placed under natural day lengths in February. They exhibited two emergence peaks that corresponded to the times of dusk in Tsukuba and on the island, respectively. Males emerged precociously if a lure containing synthetic female sex pheromone was placed in their container, whereas the females’ behavior was unaffected. Previous observations that mated females dig deeper in the soil than virgin females, males or mated males were confirmed. To explore the underlying mechanism controlling the behavioral change associated with mating, liquid material derived from the male accessory glands, seminal vesicles and female bursa copulatrix was injected into beetles, but without any significant influence on burrowing behavior. No significant influence was also observed in beetles injected with anisomycin, an inhibitor of protein synthesis related to memory in other animals.