Effects of photoperiod and temperature on the induction of adult diapause in Dolycoris baccarum (L.) (Heteroptera: Pentatomidae) from Osaka and Hokkaido, Japan

Effects of photoperiod and temperature on the induction of adult diapause were examined in Dolycoris baccarum (L.) collected in Osaka and Hokkaido, Japan. Adults started reproduction soon after adult emergence under long-day conditions, while they entered diapause under short-day conditions. The critical photoperiod for the induction of diapause was between 13 and 14 h and between 15 and 16 h in insects of the Osaka and Hokkaido populations, respectively. Under long-day conditions, most insects of the Osaka population emerged as reproductive adults at any temperature used, whereas those in the Hokkaido population tended to show lower incidence of diapause as the temperature increased. Preoviposition periods in females of the Osaka population were shorter than those of the Hokkaido population. The duration of diapause in the Osaka population was shorter at 30 degrees C than at 25 degrees C under short-day conditions. In Osaka, D. baccarum is assumed to produce three generations a year, like several other seed-sucking bugs. In Hokkaido, a greater proportion of adults produces the second generation in summer under long daylengths.