Abstract: 【Aim】 Myzus persicae is one of the most important tobacco pests. Aphidius gifuensis is a critical parasitoid for this pest. This study aims to screen out the optimal juvenile hormone analogs that can delay the emergence time of A. gifuensis and to solve the problems in the actual mass rearing process of aphid control, such as the inconsistency of emergence of A. gifuensis wasps and the insufficient quantity of A. gifuensis wasps. 【Methods】 The effects of five juvenile hormone analogs including S-hydroprene (ZR-512), kinoprene (ZR-777), methoprene (ZR-515), fenoxycarb ［ethyl (2-(p-phenoxy) ethyl) carbamate］ and juvenile hormone Ⅲ (2,6-nonadienoic acid) at different concentrations (5 000, 1 000, 200, 40 and 8 ng/μL) on the emergence rate, emergence time, proportion of female adults and parasitism rate were determined by liquid immersion method, the contents and activities of molting-related enzymes in A. gifuensis pupae treated with the five juvenile hormone analogs at the concentration of 1 000 ng/μL were measured by biochemical method, and the optimal analogs that can delay the emergence time of A. gifuensis were screened. 【Results】 Among the tested five juvenile hormone analogs at different concentrations, 200 ng/μL ZR-777 and 1 000 ng/μL ZR-512 significantly delayed the emergence time of A. gifuensis by 44.00 and 56.00 h, respectively, as compared to the control (treated with 10% acetone), and ZR-515 and fenoxycarb at different concentrations significantly reduced the emergence rate of A. gifuensis as compared to the control. Compared with the control group, the five juvenile hormone analogs at different concentrations showed no significant effect on the adult longevity of A. gifuensis, while 1 000 and 40 ng/μL ZR-777 reduced the proportion of female adults of A. gifuensis. Treatments with 200 ng/μL ZR-777, 1 000 ng/μL ZR-512 and 5 000 ng/μL ZR-512 had no significant effect on the parasitism rate of A. gifuensis. The content and activity of phenoloxidase and the activity of chitinase in A. gifuensis pupae treated with ZR-512 were the lowest when the five juvenile hormone analogs were applied at the concentration of 1 000 ng/μL. 【Conclusion】 In practice, 1 000 ng/μL ZR-512 or 200 ng/μL ZR-777 can be used to deal with A. gifuensis, so as to delay its emergence time and to obtain its wasps in sufficient quantity and with good consistency. The results provide theoretical references for the mass rearing of A. gifuensis.

Key words: Aphidius gifuensis, Myzus persicae; juvenile hormone analogs, growth and development, parasitism, phenoloxidase, chitinase