Stethorus japonicus Kamiya (Coleoptera: Coccinellidae) is an indigenous ladybird beetle in Japan, which feeds on many spider mite species. We evaluated the development, survivorship and life-history parameters of this lady beetle on a diet of eggs of the two-spotted spider mite, Tetranychus urticae Koch (red form) (Acari: Tetranychidae). In addition, the effect of short photoperiod on its reproduction was assessed. Survival rates from egg to adult were more than 71% at temperatures between 17.5 and 30°C. The highest immature mortality was 100% at 35°C followed by 76% at 15°C and 52% at 32.5°C. The lower threshold temperature for development from egg to egg-laying adult was 13.0°C and the thermal constant was calculated as 238.7°days. Based on these data, the maximum number of generations that could complete development in a year under field conditions in Ibaraki, central Japan, would be between five and seven. The intrinsic rates of natural increase (r m ) were 0.093 at 20°C, 0.156 at 25°C and 0.241 at 30°C. Reproductive diapause was induced at photoperiods with light phases shorter than 13 h at 18°C.

No abstract