Abstract: 【Aim】 To clarify the overexpression and detoxification effect of CYP6AE76 in vivo on Cry1Ab protein in Conogethes punctiferalis larvae after fed with Cry1Ab protein. 【Methods】 The CYP6AE76 sequence of C. punctiferalis was characterized. The expression level 
of CYP6AE76 in different developmental stages (1st-5th instar larvae) and tissues (head, midgut, hemolymph and fat body) of the 4th instar larvae as well as in the midgut and hemolymph of the 4th instar larvae of C. punctiferalis fed with Cry1Ab protein (LC₅₀=1.08 ng/cm²) for 3 d were detected by RT-qPCR. The expression level of CYP6AE76 in the midgut of the 4th instar larvae was detected and the larval weight and larval survival rate at 120 h after silencing the expression of CYP6AE76 in the 4th instar larvae of C. punctiferalis by RNAi through feeding were counted. The larval weight and the larval survival rate of C. punctiferalis at 7 d after silencing the expression of CYP6AE76 by RNAi through feeding in the newly hatched larvae followed by feeding on the Cry1Ab-containing (1.08 ng/cm²) diet were calculated. 【Results】 The open reading frame of the CYP6AE76 of C. punctiferalis is 1 572 bp in length. It encodes 524 amino acids, with a molecular weight of about 60.34 kD, and belongs to the CYP6 family gene. Developmental expression profiling showed that CYP6AE76 is expressed throughout the larval stage of C. punctiferalis, with the highest expression level in the 1st instar larval stage and its expression level gradually decreasing with increasing larval instar. Tissue expression profiling revealed that the expression level of CYP6AE76 in the midgut of the 4th instar larvae was the highest. After the 4th instar larvae were fed with the Cry1Ab-containing (1.08 ng/cm²) artificial diet, the expression levels of CYP6AE76 in the midgut and hemeolymph were significantly up-regulated as compared to those in the control group. After silencing CYP6AE76 by RNAi, the body weight of the newly hatched larvae fed on the artificial diet containing Cry1Ab protein significantly decreased. 【Conclusion】 CYP6AE76 may participate in detoxifying the Cry1Ab protein ingested by C. punctiferalis larvae.

Key words: Conogethes punctiferalis, cytochrome P450, Cry1Ab protein, survival rate, RNAi; gene expression level