Studies On Diapause Of Orthaga Achatina Butler (Lepidoptera: Pyralidae)

Orthaga achatina Butler (Lepidoptera: Pyralidae) is a kind of important landscapeplant pest.This thesis on O. achatina is not only aimed at the mechanism of diapause,but also have significance for providing theoretical basis on screening forecast factorscorrectly. The main results are reported as following:Studies on diapause induction of Orthaga achatinaThe reaction of diapause for different photoperiod were observed at25℃and28℃in the constant temperature incubator, the sensitive stage were investigated by longand short photoperiod comlination at different instars of this insect. The photoperiodicresponse curves in O. achatina showed that this insect is a long-day developmentspecies with a critical day length of13.565h at25℃and13.364h at28℃. The sensitivestage to short light of12h was the4-5th instar at25℃,while the1-3rd instar and the eggstage were the less sensitive stages.Research on diapause termination in Orthaga achatina by low temperatureWe designed experiment at2℃、5℃、8℃which were processing50d、70d、90drespectively. The author observed emergence rate when O. achatina at25℃aftertransering from different low temperature treatments.The tests indicate that theemergence rate was82.4%when treated50d at8℃,and showed that this treatment hadcertain effect on diapause termination better than the others.Changes in glutathione redox cycle of Orthaga achatina at the phase ofdiapauseAccording to research results on diapause induction and diapause termination of O.achatina,we further examined changes in glutathione redox cycle of it at phases ofdiapause process. The results showed that the shift of glutathione redox cycle maintainsin reductive state from25℃to the20th days at8℃, may be during this period O.achatina were at diapause initiation phase. Compared to initiation phase, the glutathioneredox cycle was in an oxidative state at diapause termination phase which between the 30th days at8℃to the10th days at25℃. Taken together, our results showed that the30th days at8℃was the beginning of diapause termination.