Estimation of number of annual generations using effective heat unit of development for the rice bug, Leptocorisa chinensis (Dallas)(Hemiptera : Alydidae)

We investigated the effects of a range of constant temperatures (18–30°C) on the development of eggs, nymphs and the pre-oviposition period of adult females in Leptocorisa chinensis (Dallas). The duration of all stages decreased as the temperature increased from 18 to 30°C. Developmental thresholds of 8.1, 10.1 and 9.6°C were estimated for the eggs, nymphs and pre-oviposition period, respectively. Thermal constants of 147 and 370 d-degrees above thresholds of 8.1 and 10.1°C were required for the development of the eggs and nymphs, respectively. The pre-oviposition period required 256 d-degrees above the developmental threshold of 9.6°C. After placing individuals collected in November and February in an incubator in the laboratory, 469.7 d-degrees above 9.6°C, a threshold for nondiapause female adults that was assumed to be equal to that of diapause female adults, were estimated to be required for the pre-oviposition period of individuals that had overwintered. The present results were useful to predict the field population phenology of L. chinensis in Hyogo Prefecture.