Abstract:

 【Aim】 The aim of this study is to clarify the effective doses of exogenous juvenile hormone (JH) and the optimal treatment period for rapid diapause termination in the green lacewing, Chrysoperla sinica. 【Methods】 The pre-oviposition period, oviposition duration, female longevity and number of eggs laid per female of diapause adults of C. sinica exposed to different doses of exogenous JH (0, 5, 15, 25 and 35 μg/adult) by topical application and the changes of these four indexes of diapause C. sinica adults treated at different day-old age (0, 5, 10, 20, 30 and 40 day-old) with 15 μg/adult exogenous JH were determined. 【Results】 The pre-oviposition period of the diapause adults of C. sinica exposed to 15 and 25 μg/adult exogenous JH was 6.82 and 6.29 d, respectively, significantly shorter than that (10.55 d) in the control group (only treated with acetone). The oviposition duration, female longevity and the number of eggs laid per female of the diapause adults of C. sinica exposed to 15 μg/adult exogenous JH were all the highest, significantly higher than those of the control group. After diapause C. sinica adults were exposed to 15 μg/adult exogenous JH at different day-old age, the pre-oviposition period of adults treated at 0, 5,10 and 20 day-old age was significantly shorter than that of the control group non-subjected to exogenous JH treatment, the oviposition duration and female longevity of the adults treated at 10, 20 and 30 day-old age showed no significant difference from those of the control group non-subjected to exogenous JH treatment, while the numbers of eggs laid per female of the adults treated at 10, 20 and 30 day-old age were significantly reduced as compared to the control group non-subjected to exogenous JH treatment. Both adults subjected and non-subjected to exogenous JH treatment at 20 day-old age had higher fecundity. 【Conclusion】 Considering all the four indexes of pre-oviposition period, oviposition duration, oviposition amount and female longevity, we recommend 15 μg/adult exogenous JH as the optimal dose for the rapid diapause termination of C. sinica. The optimal treatment period for rapid diapause termination is the adult diapaused for 20 d, which has the least effect on the reproductive ability of C. sinica adults. The bottleneck problem of long time needed for diapause termination of C. sinica has been solved in this study, providing a new idea for the efficient storage and utilization of natural enemies with adult diapause and the fast diapause termination.

Key words: Chrysoperla sinica, exogenous juvenile hormone, diapause termination, post-diapause development, reproductive potential