|Li, Wenxiang - CHINA AGRICULTURAL UNIV|
|Li, Jiancheng - HEBEI ACAD AGRICULTURE|
|Lu, Ziyun - HEBEI ACAD AGRICULTURE|
|Pan, Wenliang - HEBEI ACAD AGRICULTURE|
|Liu, Xiaoxia - CHINA AGRICULTURAL UNIV|
|Zhang, Qingwen - CHINA AGRICULTURAL UNIV|
Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 28, 2007
Publication Date: May 1, 2008
Citation: Li, W., Li, J., Coudron, T.A., Lu, Z., Pan, W., Liu, X., Zhang, Q. 2008. The role of photoperiod and temperature in diapause induction of the endoparasitoid wasp, Microplitis mediator (Haliday) (Hymenoptera: Braconidae). Annals of the Entomological Society of America. 101(3):613-618. Interpretive Summary: The need for an effective and efficient biological control agent for the cotton bollworm, one of the most destructive pests of economically important field crops throughout the world, is enhanced by the increased resistance of the bollworm to nearly all types of chemical control. A beneficial wasp has been shown to be an effective biological control agent and rearing and release methods have been reported for the wasp. Long-term storage of the wasp, using a naturally occurring biological quality intended to aid in over wintering, was shown to be a feasible method to induce an artificial stage for long-term storage. This long-term storage method will enable the mass production of the wasp in the large numbers required for field releases and will be an invaluable technique to beneficial insectaries rearing the wasp.
Technical Abstract: Diapause in Microplitis mediator is manifested during the pupal stage and normally occurs during the winter season because of a photoperiodic response which is highly dependant on temperature. In the reported study, diapause was determine by photoperiod and mediated by temperature, which supports the definition of facultative diapause (Lees, 1955). The larval stage of the parasitoid was the most sensitive to diapause induction. No diapause was observed at > 20degC regardless of the photoperiod. In contrast, when larvae were exposed to 16degC, 18degC and 20degC combined with a photoperiod of 10: 14 LD, the percentages of parasitoids that entered pupal diapause was 97.92, 87.78 and 26.207%, respectively. The critical photoperiods of LD 7.03: 16.97 and 12.21: 11.79 at 16degC and LD 8.09: 15.91 and 12.62: 11:38 at 18degC were demonstrated. Both long and short photoperiods were found to affect the critical day length which inferred a role for circadian rhythms in the induction of diapause. The best condition for diapause induction tested in this study was 16degC and 10:14 L:D.