Abstract:  The toxicity of eleven insecticides of different categories on adults of Trichogrammatoidea bactrae Nagaraja and the sublethal effects of insecticides on their reproduction under laboratory conditions were studied, so that the safety of insecticides to adults of T. bactrae was evaluated. The results showed that the adults of T. bactrae were the most susceptible to avermectins at 8 h after exposure to fresh, dry insecticide films in glass vials, the LC₅₀ and sublethal concentration (LC₃₀) values were 0.1984 mg/L and 0.1660 mg/L, respectively, and second susceptible to fipronil (LC₅₀ and LC₃₀ values were 0.2027 mg/L and 0.1903 mg/L, respectively), chlorfenapyr (LC₅₀ and LC₃₀ values were 0.3069 mg/L and 0.2038 mg/L, respectively), spinosad (LC₅₀ and LC₃₀ values were 1.3630 mg/L and 1.0481 mg/L, respectively), cartap (LC₅₀ and LC₃₀ values were 8.1042 mg/L and 6.7891 mg/L, respectively), betacypermethrin (LC₅₀ and LC₃₀ values were 10.3647 mg/L and 5.8035 mg/L, respectively) and diafenthiuron (LC₅₀ and LC₃₀ values were 11.5318 mg/L and 9.9212 mg/L, respectively). The LC₃₀ values of avermectins, chlorfenapyr, cartap, diafenthiuron, spinosad and fipronil had significant effects on the longevity and fecundity of T. bactrae. After treated with these insecticides, the longevity of females (1.00-1.67 d) was shortened, and the number of eggs parasitized per female (0-21.70) decreased, and therefore the life table parameters (R₀, r_m, λ and T) of T. bactrae were statistically lower than those in the control. The field recommended concentration of indoxacarb, chlorfluazuron, Bacillus thuringienesis and tebufenozide had no effect on the longevity and fecundity of T. bactrae, but after treated with these insecticides, the R₀, r_m and λ of T. bactrae were higher than those in the control. However, the longevity of females (3.77 d) was significantly extended, and the number of eggs parasitized per female (55.47) was significantly increased after the adults of T. bactrae were exposed to betacypermethrin, and therefore the life table parameters of T. bactrae were statistically higher than those in the control. The results suggest that chlorfluazuron, indoxacarb, B. thuringienesis and tebufenozide are safe to T. bactrae, so these insecticides are compatible to these parasitoids when used for control of Plutella xylostella. Diafenthiuron, however, is evaluated as harmful to the fecundity of T. bactrae, and timing of application of this insecticide is critical.

Key words: Trichogrammatoidea bactrae; insecticide, toxicity, reproduction, life table parameters, sublethal effect