Abstract
Overwintering females of Pseudaulacaspis pentagona (Targioni) entered a reproductive diapause, and the ovary development in females collected before December 22 was retarded at 20°C under short (L10 : D14) and long (L15 : D9) days. In contrast, ovarian eggs in females collected after the beginning of the year developed normally. I examined the effects of temperature on the development of overwintering females that infested tea branches and on the hatch of the first generation at various constant temperatures. The base temperature was determined to be 10.5°C and 10.9°C for 50% of the females to begin laying eggs and for the egg hatch to reach a peak, respectively. Seasonal changes in oviposition of the overwintering generation and hatch of the first generation were monitored from 1998–2002 at Kanaya, Shizuoka Prefecture. When the base temperature was assumed to be 10.5°C and day-degrees (DD) were summed from January 1, 50% of the females began laying eggs when an average of 149 DD had accumulated, and the peak of hatching coincided with an average of 288 DD. The logistic equation y=1/[1+exp{−(α0+α1x)}] (y, proportion of parous females or hatch; x, DD accumulations; α0 and α1, constants) was used to model a sequence of the population events and to predict the optimum timing of insecticide application for controlling the first-generation larvae of P. pentagona.