Abstract: 【Aim】 In integrated pest management, chemical control also presents a certain lethality to natural enemy resources. To alleviate this contradiction, the study aims to investigate the effects of sublethal doses of chlorfenapyr and chlorpyrifos on the growth, reproduction, and detoxification enzyme activity and gene expression in Blattisocius dentriticus. 【Methods】 The 2-3 day-old adults of B. dentriticus were treated with chlorfenapyr and chlorpyrifos for 24 h using the residual film method, and the sublethal doses of the two pesticides were determined. The biological characteristics (fecundity, oviposition period, egg hatching rate and longevity of female adult) of F₀ and F₁ generations of female adults exposed to LC₁₀ and LC₃₀ of the two pesticides were investigated and compared. The changes in the activities of glutathione S-transferase (GST), cytochrome P450 (CYP450) and carboxylesterase (CarE) and the expression levels of their genes in B. dentriticus adults treated with LC₁₀, LC₃₀ and LC₅₀ of the two pesticides were detected using enzyme activity assay and RT-PCR, respectively. 【Results】 The LC₅₀ values of chlorfenapyr and chlorpyrifos against B. dentriticus adults at 24 h were 42.56 mg/L and 72.42 mg/L, respectively. After B. dentriticus adults were treated with LC₁₀ and LC₃₀ of chlorfenapyr and chlorpyrifos, the longevity and oviposition period of F₀ generation of female adults were significantly shortened (P<0.05) as compared with those in the control (treatment with water), while the fecundity and egg hatching rate showed no significant change. The activities of GST, CYP450 and CarE of adults stayed stable after the adults were treated with chlorfenapyr and chlorpyrifos at LC₁₀ and LC₃₀, but significantly increased when the adults were exposed to the dose of LC₅₀ (P<0.05). Gene expression profiles revealed that two GST genes (BdGST3 and BdGST6), three CYP450 genes (BdCYP2-4 ), and five CarE genes (BdCarE1-5) were significantly up-regulated after the adults were treated with chlorfenapyr at the doses of LC₁₀, LC₃₀ and LC₅₀, while the expression levels of three GST genes (BdGST1, BdGST3 and BdGST4), three CYP450 genes (BdCYP2, BdCYP5 and BdCYP6) and two CarE genes (BdCarE1 and BdCarE2) were significantly up-regulated when the adults were treated with chlorpyrifos at the three doses. 【Conclusion】 The results show that chlorfenapyr and chlorpyrifos at LC₁₀ and LC₃₀ inhibit the growth and reproduction of F₀ female mites of B. dentriticus, the two pesticides at LC₁₀, LC₃₀ and LC₅₀ induce the expression of GST, CarE and CYP450 genes, and the activities of GST, CarE and CYP450 in adults exposed to the two pesticides at LC₅₀ are significantly increased. This study provides a theoretical basis for screening the resistant strains of B. dentriticus and their application in fields.

Key words: Blattisocius dentriticus; chlorfenapyr, chlorpyrifos, growth and reproduction; detoxification enzyme, gene expression level