Photoperiodic Induction of Diapause, Hibernation and Voltinism in Piezodorus hybneri (Heteroptera: Pentatomidae)

Abstract

Developmental zero from egg to the adult emergence in the stink bug, Piezodorus hybueri, was 14.2°C in both sexes and effective heat units for females and males were 283.0 and 277.8 day-degrees, respectively. Developmental zero for preoviposition period was 18.4°C and effective heat unit was 70.0 day-degrees. Critical photoperiod for the diapause induction in Kumamoto Prefecture was considered to fall between 12L-12D and 13L-11D. Most females emerged on and after 15 September had immature ovaries and entered reproductive diapause. Survivorship curves of overwintering females and males declined steadily, and 35.0% of females and 28.6% of males remained alive until 6 April next spring. Oviposition of these overwintered females occurred between middle April and early May. The number of generations per year was estimated with the developmental zero and the effective heat unit of P. hybneri. The stink bug possibly has four generations per year in Kyushu, southwest Japan. The peak of the start of oviposition in the first generation was estimated in late June. Therefore, it is concluded that mated females with mature eggs which invaded summer soybean fields from early July are newly emerged adults of the first generation.