Physiological Responses Of Adult Grapholita Molesta Busck To High Temperature Stress

Grapholita molesta Busck (Lepidoptera: Olethreutidae), referred as oriental fruit moth,also known as twigs breaking worms. In recent years, as the global warming, the extreme hightemperature appeared frequently. The occurrence of G. molesta has a increasing tendency yearby year. It is the basic solution to know the population dynamics and the damage of hostconversion by exploring the physiological responses of adult G. molesta under heat stress. Inthis study, the newly emerged adults of G. molesta were stressed at29,32,35,38and41℃respectively, and each temperature treatment have five different stress time (0.5h,1.0,1.5,2.0and2.5h), then the variations of the soluble protein content, soluble sugar content andprotective enzymes vitality were tested. The results are as follows:1. The soluble protein content per gram in the newly emerged female adults of G.molesta,which were successively cultivated at26℃, is significantly higher than that in the males. Withthe stress temperature and stress time changing, the soluble protein content in the newlyemerged adults have different variations. The soluble protein content in the female adultsshowed a great fluctuation along with the increase of stress time after high heat stress at32,35and41℃; The soluble protein content of the male adults fluctuated greatly with theincrease of the stress time under the heat stress at32and38℃.2. The soluble sugar content per gram in the adults of G. molesta, which weresuccessively cultivated at26℃, showed distinct significance. And it was significantly higherin males than that in the females. It has different variations in the adults of G.molesta with theincrease of stress time under different stress temperature or the increase of stress temperatureunder the same stress temperature. When the adultswere stressed at29℃, the soluble sugarcontent decreased significantly than that stressed at other temperatures with the increase of thestress time. For the males stressed at29℃, the soluble sugar content per gram declinedsignificantly at first, then showed a tendency to increase, and showed a great difference of thevariation trend with stress time changing compared to the variation trends at othertemperature treatments. The soluble sugar content showed the most obviously variation withstress temperature changing when stressed for2.5h in the female adults. While in the maleadults, it showed a tendency “up-down-up-down” with stress temperature changing. 3. SOD activities in the newly emerged female adults of G. molesta, which weresuccessively cultivated at the optimal temperature (26℃), was significantly higher,approximately four times, than that in males. It was shown that SOD activities in femaleadults stressed at different temperatures tended to decrease as the stress time went longer, andall the activities were lower than that in control. Variations of SOD activities stressed between29and38℃have significant difference. SOD activities in the males at41℃rised upsignificantly with the increase of the stress time. When stressed for the same time, SODactivities in female adults of G. molesta present a tendency of “down-up-down-up” with theincrease of the stress temperature, while for the males, it increased significantly at41℃.4. POD activities in newly emerged female adults of G. molesta, successively cultivatedat optimal temperature (26℃), were significantly higher than that in males. POD activitieswere significantly higher than that in the control when stressed at38℃and were significantlylower than that in the control when stressed at41℃for1h. It has no significant differencebetween male adults and the control stressed29-38℃. When stressed at41℃for1.0,1.5and2.5h, POD activities in males were significantly lower than that in the control. Two peaks ofPOD activities in females appeared at32and38℃when stressed between0.5and2.0h. Asfemales stressed for2.5h, POD activities increased at first and then decreased with highertemperature treatments, and the maximum value occurred at38℃. POD activities in malesstressed for the same time increased first and decreased then as a whole.5. CAT activities in the newly emerged female adults of G. molesta, successivelycultivated at26℃, were significantly higher than that in males. CAT activities in femaleadults of G. molesta stressed at35℃for2.5h were significantly higher than that in any othertime treatments. CAT activities in males stressed at29℃for0.5h were significantly higherthan that in the other time treatments and the control, And it declined to the same value ofthe control after2.5h. As the females stressed between1.5and2.5h, CAT activities stressedat38and41℃were significantly lower than other temperature treatments. As the malesstressed for the same time, CAT activities tended to decrease with higher temperatures.