Abstract
Adalia bipunctata L. has low developmental thresholds ( t ) for postdiapause and nondiapause development that adapt it to activity early in the season. Postdiapause reproductive development leading to oviposition requires an accumulation of 87 degree-days ( K ) above a relatively low developmental threshold temperature ( t ) of 6.8°C. Overwintering adults disperse and initiate oviposition during early to mid-May. The linearly derived ( t ) and ( K ) values of 263 ± 9.0 degree-days above 9.0°C for preimaginal development and daily maximum-minimum temperatures from outdoors accurately predicted outdoor developmental rates. Preimaginal development outdoors during June and July required 269 ± 12 degree-days above 9.0°C under conditions of excess prey. In the field, there are two to three generations per year in the Ithaca, N.Y., area. The critical photoperiod for diapause induction in the Ithaca, N.Y., (~42°N) population lies between LD 13:11 and LD 14:10 (23°C). Short daylengths maintain diapause, and during autumn the duration of diapause is quantitatively related to photoperiod. Diapause completion does not require chilling: during winter-early spring. photoperiod may exert some influence on the timing of diapause termination.
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