2004 Volume 39 Issue 3 Pages 511-519
Scolothrips takahashii is an indigenous thrips in Japan that feeds on many spider mite species. To evaluate whether S. takahashii has potential as a biological control agent for spider mites, we investigated the development, survivorship and life-history parameters of S. takahashii on a diet of Tetranychus urticae (red form) eggs at different temperatures. More than 74% of thrips eggs hatched and more than 76% of newly hatched larvae attained maturity at 15–35°C. No females laid eggs at 37.5 or 40°C. The lower threshold temperature for development from egg to oviposition was 11.7°C and the thermal constant was calculated as 204.1 degree-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 seven and ten. Mating was unnecessary to induce oviposition but unmated females produced only male progeny. At 25°C, females laid a mean of 90.5 eggs during a mean oviposition period of 17.8 days. The values for the intrinsic rate of natural increase (rm), one important life-history parameter, were 0.113 at 20°C, 0.195 at 25°C, and 0.246 at 30°C. These results suggest S. takahashii has considerable potential as a biological control agent against spider mites.
