Abstract: 【Aim】 This study aims to explore the sublethal effects of carbendazim on the growth and development and detoxifying enzyme activities of the larvae of the Italian honeybee, Apis mellifera ligustica. 【Methods】 Larvae in two treatment groups were fed with diets containing 0.25 and 0.75 mg/g a.i. carbendazim (relative mortality rate<5%), respectively, while those in the control group with the normal diets. All larvae were reared with different diets until eclosion, and their growth indexes (pupal weight, pupation rate and eclosion rate), total protein concentration, and T-SOD and detoxifying enzyme activities were assayed. 【Results】 There were no significant differences in the pupal weight, pupation rate and eclosion rate of A. m. ligustica among all groups (P>0.05). The total protein concentration in pupae decreased in the treatment group fed with diets containing 0.75 mg/g a.i. carbendazim (P<0.05). The total superoxide dismutase activities in the treatment groups fed with diets containing 0.25 and 0.75 mg/g a.i. carbendazim tended to be significantly higher than that in the control group, being 1.35- and 1.28.fold as high as the control group, respectively. The juvenile hormone titer in the treatment groups fed with diets containing 0.25 and 0.75 mg/g a.i. carbendazim were significantly higher than that in the control group, being 1.57- and 1.75-fold as high as the control group, respectively. Ecdysone titers in the treatment groups fed with diets containing 0.25 and 0.75 mg/g a.i. carbendazim were only 62% and 65% of the control group, respectively (P<0.05). The cytochrome P450 (CYP450) and carboxylesterase (CarE) activities were increased in the low-dose (0.25 mg/g a.i.) treatment group (P<0.05), and then returned to the normal level in the high-dose (0.75 mg/g a.i.) treatment group, but no inhibitory effect on the activities of the two enzymes was found (P>0.05). There was no significant difference in glutathione-S-transferase (GST) activity between treatment groups and the control group (P>0.05). 【Conclusion】 These results demonstrate that sublethal doses of carbendazim restrain the growth and development of A. m. ligustica larvae, but do not cause their acute death, and may cause potential harm to the stability and development of the colony.

Key words: Apis mellifera ligustica, carbendazim, sublethal effect, growth and development, detoxifying enzyme