Abstract: 【Aim】This study aims to make clear the sublethal effects of the botanical insecticides azadirachtin and celangulin on Ostrinia furnacalis larvae and their effects on the activities of detoxification enzymes, so as to explore the detoxification mechanism of O. furnacalis on these two pesticides. 【Methods】The toxicity of azadirachtin and celangulin to the 3rd instar larvae of O. furnacalis in 72 h was analyzed by dipping method. The 3rd instar larvae of O. furnacalis were exposed to sublethal concentrations (LC₁₀, LC₂₀ and LC₄₀) of azadirachtin and celangulin for 6, 12, 24, 48 and 72 h, and the activities of three main detoxification enzymes including glutathione S-transferase (GST), carboxylesterase(CarE) and cytochrome P450(CYP450) were measured by enzyme-linked immunosorbent assay (ELISA). 【Results】 TheLC₁₀, LC₂₀ and LC₄₀ values of azadirachtin against the 3rd instar larvae of O. furnacalis in 72 h were 0.352, 0.614 and 1.290 mg/L, respectively, and those of celangulin against the 3rd instar larvae of O. furnacalis in 72 h were 0.032, 0.086 and 0.321 mg/L, respectively. After the 3rd instar larvae of O. furnacalis were exposed to LC₁₀, LC₂₀ and LC₄₀ of azadirachtin, the GST activity was firstly inhibited, then induced, and finally inhibited, and 12-h exposure to LC₁₀ of azadirachtin had an induction effect on the GST activity. LC₁₀, LC₂₀ and LC₄₀ of azadirachtin mainly inhibited the activities of CarE and CYP450. After the 3rd instar larvae of O. furnacalis were exposed to LC₁₀, LC₂₀ and LC₄₀ of celangulin, the activities of GST and CarE were mainly inhibited, and the CYP450 activity was firstly inhibited and then induced, while 72-h exposure to LC₁₀ of celangulin had an induction effect on the CYP450 activity. 【Conclusion】Azadirachtin and celangulin can affect the detoxification metabolism of O. furnacalis, and the inhibition of azadirachtin and celangulin on the activities of GST, CarE and CYP450 in O. furnacalis is one of the reasons for their insecticidal activity, GST only plays a certain role in metabolism on low concentration (LC₁₀)  of azadirachtin and CYP450 only plays a certain role in metabolism on low concentration (LC₁₀)  of celangulin.

Key words: Ostrinia furnacalis, azadiractin, celangulin, sublethal concentrations, glutathioneStransferase, carboxylesterase, cytochrome P450