スジグロシロチョウ Pieris melete MENETRIES (Lepidoptera, Pieridae) の蛹休眠 : 特に休眠誘起および休眠消去と光周期  [in Japanese] Photoperiodic Induction and Termination of Diapause in the Fragrant White, Pieris melete MENETRIES (Lepidoptera, Pieridae)  [in Japanese]

1.スジグロシロチョウPieris melete MENETRIES(以下スジグロと略記)の東京産個体群における蛹休眠誘起の臨界日長, 休眠誘起に必要な光周期の回数とその感受期, 休眠消去と光周期の関係について実験した.実験に用いたスジグロは, 約35°40′Nの東京都日野市または小金井市で母蝶を採集し, 採卵して得た.2.夏型雌から産まれた世代の臨界日長は, 20±1℃で約13時間30分と推定された.3.ほぼ完全な休眠誘起には, 20±1℃で3令以後に少なくとも12日以上の短日周期(LD8 : 16)が必要であった.幼虫期後半に9∿12日の連続した長日周期(LD14 : 10)が与えられるとほぼ完全に休眠が抑制された.4.先に与えられた光周期の影響を妨げる効果は, 短日より長日のほうが高い.5.20±1℃ではスジグロの休眠消去に光周期はほとんど影響を与えない.

The photoperiodic induction of diapause in a Tokyo population of Pieris melete MENETRIES was studied by rearing larvae in different photoperiods ranging from LD 8 : 16 to LD 16 : 8 hr at 20±1℃. The critical photoperiod in progeny of summer-form females was about 13.5 hr. A high percentage of diapause pupae was obtained when larvae were continuously exposed to a short photoperiod (LD 8 : 16 hr) for 12 days from the 3rd instar to pupation. When 5th instar larvae which had been exposed to the short photoperiod were transferred to a long photoperiod (LD 14 : 10 hr), 53% of the resulting pupae averted diapause. It seems that the influence of the preceding photoperiodic conditions is more effectively eliminated by a long photoperiod than by a short one. When diapausing pupae were kept at 20±1℃ under three different conditions, that is, long and short photoperiods and continuous darkness, adults emerged from them in about the same periods of time. Thus the elimination of diapause was little affected by photoperiod.