抄録
ミヤマチャバネセセリの越冬世代幼虫の老熟・蛹化は,茨城県つくば市の野外条件で10月上旬から12月中旬に起こり,そのピークは10月下旬から11月上旬であった.幼虫が10月に老熟した場合には前蛹期間は平均約5日だったが,11月半ばを過ぎて老熟した場合には前蛹期間は平均約20日になった.越冬蛹が,12L:12Dまたは15L:9Dの日長条件下の様々な温度で飼育された.蛹休眠は野外条件で1月に覚醒した.日長条件は蛹期間の長さにほとんど影響しなかったが,温度の日変化は蛹の発育に影響を与えた.変温条件で蛹が飼育された場合,平均温度が同じ恒温条件よりも,特に低温の場合に蛹期間が短くなった.越冬蛹の発育零点と有効積算温度は,恒温条件では13.0-13.3℃と158-165日度,変温条件では12.2-12.3℃と171-173日度で,変温条件で発育零点が低かった.蛹は周囲の温度が低い早春に,このメカニズムを使って早く羽化することができるだろう.
Overwintering generation larvae of Pelopidas jansonis matured and pupated from early October to mid-December with a peak in late October/early November under outdoor conditions in Tsukuba city, Ibaraki prefecture, central Japan. Overwintering pupae were reared under various constant and fluctuating temperatures superimposed on a photoperiod of 12L:12D (12h light:12h dark) or 15L:9D. The pupal diapause terminated in January. The photoperiod did not have a significant effect on the duration of the pupal stage, but the thermoperiod had a significant effect on the development of pupae. When pupae were kept under fluctuating temperatures, the pupal period was shorter than that at constant temperatures corresponding to the mean of fluctuating temperatures, especially under lower temperature conditions. The developmental zero and the thermal constant of pupae were 13.0-13.3℃ and 158-165 day-degrees and 12.2-12.3℃ and 171-173 day-degrees, when pupae were reared under constant and fluctuating temperature conditions, respectively. Pupae may develop faster in the field by using this mechanism in early spring when the surrounding temperature is low.
