Effect of temperature on life history traits of the predatory thrips, Scolothrips takahashii Priesner (Thysanoptera: Thripidae)

Abstract

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 (r m ), 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.

Functional response of the predator Scolothrips takahashii to hawthorn spider mite, Tetranychus viennensis: effect of age and temperature

“…Females exhibited Type II responses at various ages tested, and the magnitude of functional response in females aged 3-9 d were significantly greater than 15 d or more. This could be attributed to fact that egg reproduction in females reached a peak at this age at 25°C (Gotoh et al, 2004a). While in males aged 12 d or more, the responses were confirmed to be Type I, their inability to respond to increasing prey density indicated that physiological senescence in males was faster than in females.…”

“…Females of S. takahashii were more voracious than males. This, combined with the female-biased sex ratio in population of S. takahashii (Gotoh et al, 2004a), indicates that female may play a more important role in the biological control of phytophagous mites. In this study, we focused mainly on prey eggs consumed by S. takahashii adults, because the egg stage comprises the major proportion of a T. viennensis population (Liu and Wang, 1965;Li et al, 2005).…”

“…This study confirms that the type II functional responses of S. takahashii adults to T. viennensis eggs remain unchanged over a temperature range of 20-35°C, but that the magnitude of the functional response of S. takahashii differed obviously among various temperatures. This can be attributed to the fact that the predators are more active and have greater reproductive rates at higher temperature (Gotoh et al, 2004a). The variation in functional response with temperature could be described by an extended model indicating that temperature influences both handling time and attack rate in females, but does not influence the attack rate in males.…”

“…The effects of ageing on the functional response of the predatory thrips were investigated for both male and female thrips with 3, 6, 9, 12, 15, and 18 d old adults at the conditions of 25±1°C, 60±10% RH and a photoperiod of 16:8 (L:D) h, since the mean oviposition period in female S. takahashii was 18 days (Gotoh et al, 2004a). Synchronized eggs were prepared as above.…”

“…Insecticide resistance, coupled with increasing public concern about pesticide residues in both food products and the environment, has led to an intensive search for alternative methods of managing insect pests in apple orchards. Therefore, there has been an increasing interest in controlling spider mites with biological control agents (Gotoh et al, 2004a;Zhang et al, 2005).…”