Abstract
The photoperiodic response curve for pupal diapause induction of the white cabbage butterfly, Pieris rapae crucivora Boisduval was determined in several populations of the Japan Archipelago. Larvae were reared under different photoperiods ranging from 8L16D to 16L8D at 20±0.5°C. The critical photoperiods for pupal diapause induction were 14 h 40 min for the Iwamizawa population (43°10′N), 13 h 15 min for the Sendai population (38°15′N), 13 h 10 min for the Nagaoka population (37°23′N), 12 h 08 min for the Okayama population (34°39′N), 11 h 50 min for the Matsuyama (33°50′N) and Kagoshima (31°35′N) populations and 11 h 15 min for the Naze population (28°23′N). The critical photoperiod increases as latitude increases. This result suggests that adaptation to a cool climate in a higher latitude region shifts the critical photoperiod for pupal diapause induction towards a longer range. The developmental zero for the larval stage in the Sapporo (43°03′N) and Matsuyama populations was calculated as 9.8°C and 9.6°C for the larval stage, respectively. These results are discussed in relation to seasonal adaptation for each population.
