Abstract: 【Aim】 Aphidius gifuensis, as a dominant parasitic wasp of Myzus persicae, has been widely used in production. However, during the propagation of A. gifuensis on a large scale, many problems such as reduced parasitic ability and smaller body size often occur after multiple generations of breeding. The purpose of this study is to screen the best rejuvenation methods by detecting and analyzing the effects of supplementing different concentrations of nutrients and trace elements on the parasitism rates and offspring adult size of A. gifuensis adults on M. persicae, and the contents and activities of growth and development-related enzymes in adults of the offspring of A. gifuensis. 【Methods】 A. gifuensis adults of the degenerated population after being reared in laboratory for 10 generations were fed with solutions of different concentrations (5%, 10% and 20%) of nutrients (honey, glucose and sucrose), and different concentrations (0.25, 0.5, 1, 2 and 4 mg/L) of trace elements including Cu, Fe, Zn, Mn and Co, the parasitism rate and offspring adult size, and the contents and activities of carboxylesterase(CarE)and phenoloxidase (PO) in adults of the offspring were determined. 【Results】 In supplemental nutrition experiments, 10% honey solution had the best rejuvenation effect on A. gifuensis, causing the parasitism rate to increase by 28.00% compared with the control (purified water), but had no significant effect on the offspring adult size. In the group fed with 10% glucose, the CarE content in adults of the offspring of A. gifuensis was the highest, which was 38.00% higher than that in the control group. The CarE activity in adults of the offspring of A. gifuensis in the group fed with 10% sucrose was the highest, which was 3-fold as high as that in the control group. In the group fed with 10% sucrose, the phenoloxidase content in adults of the offspring of A. gifuensis was the highest, which was 56.00% higher than that in the control group. The highest phenoloxidase activity in adults of the offspring of A. gifuensis was found in the group fed with 10% glucose, being 1.3-fold as high as that in the control group. In supplemental trace element experiments, the supplementation of 1 mg/L Fe had the best rejuvenation effect on A. gifuensis, resulting in the parasitism rate to increase by 25.33% compared with the control group, but had no significant effect on the offspring adult size. The CarE content in adults of the offspring of A. gifuensis in the group fed with 1 mg/L Fe was the highest, which was increased by 50.00% as compared with that in the control group. The CarE activities in adults of the offspring of A. gifuensis in groups fed with various trace elements were lower than that in the control group. In the group fed with 1 mg/L Zn, the PO content in adults of the offspring of A. gifuensis was the highest, increased by 29.31% as compared with that in the control group. In the group fed with 1 mg/L Mn, the PO activity in adults of the offspring of A. gifuensis was the highest, which was 1.51-fold as high as that in the control group. 【Conclusion】 In production, feeding 10% honey solution or supplementing 1 mg/L Fe can be used to improve the parasitic ability of A. gifuensis on M. persicae, so as to restore or regulate the degenerated population of A. gifuensis.

Key words: Aphidius gifuensis, Myzus persicae, parasitic ability, carboxylesterase, phenoloxidase