Environmental regulation of abult diapause of Graphosoma rubrolineatum (Westwood) (Heteroptera : Pentatomidae) in southern and northern populations of Japan

Effects of photoperiod and temperature on the induction of adult diapause were examined in Graphosoma rubrolineatum (Westwood) collected in Osaka (warm temperate region) and Hokkaido (subfrigid region), Japan. Many insects of the Osaka population entered diapause even under a long-day photoperiod at all temperatures used. Less than half of the insects showed a long-day photoperiodic response for the induction of diapause. In contrast, the higher the temperature, the greater the incidence of reproductive insects under a long-day photoperiod in the Hokkaido population. In Osaka where host plants of G. rubrolineatum produce seeds for only a limited period, an absence of suitable food is the primary factor which determines the timing of diapause induction. In contrast, temperature plays an important role in regulation of the life cycle of this species in Hokkaido.