Abstract: In order to definite the toxicity of tebufenozide derivative 0593 to silkworm Bombyx mori, we detected the toxicity of tebufenozide and its derivative 0593 to B. mori with food intake method, observed the growth and development of B. mori at their respective sublethal concentration, and determined their effects on endogenous protective enzymes in B. mori larvae. Based on the experimental results, we primarily discussed the action mechanism of ebufenozide derivative 0593. The results showed that the LC₅₀ of tebufenozide and its derivative 0593 to 2nd instar larvae of B. mori were 1.2863 mg·L^-1 and 0.3364 mg·L^-1 after 96 h exposure, respectively, and both were of high toxicity. At the sublethal dose, the growth and development of B. mori had been obviously affected, which could shorten larval period by 0.5～2 d. Compared with control, larval weight during molting stage, whole cocoon weight, pupal weight and pupation rate decreased of the treatments dramatically. The  PPO activity in 4th instar larvae of B. mori was activated at 6 h after treatment, and then inhibited at 12 h after treatment. Both tebufenozide and its derivative 0593 significantly activated the chitinase activity in 4th instar larvae of B. mori. 0593 showed more significant effects on endogenous protective enzymes than tebufenozide. These results indicate that tebufenozide and its derivative 0593 belong to high toxicity grade to B. mori, and have adverse effects on its development and endogenous protective enzymes. So they are not suitable to be used in and around mulberry fields.

Key words: Bombyx mori, tebufenozide, tebufenozide derivative, toxicity, protective enzymes