菜粉蝶滞育期的糖类代谢

菜粉蝶(Pieris rapae L.)蛹滞育期间体内糖原减少,同时伴以海藻糖和山梨醇的积累,滞育终止后发生相反变化。这说明滞育期间存在糖原与海藻糖、山梨醇之间的相互转化。滞育开始后,海藻糖迅速上升,其起始浓度与随后的积累与温度无关,故海藻糖的大量出现可作为菜粉蝶滞有开始的生化指标。山梨醇的产生较晚,实验结果表明,山梨醇的产生过程是一种时间进程,但其积累与温度密切相关.出间越冬蛹血淋巴糖类具有类似的变化趋势,可以认为菜粉蝶以海藻糖和山梨醇作为防寒剂,以抵抗冬季严寒低温.非滞育蛹体内不积累海藻糖和山梨醇,即使对其进行长期的低温处理,也得相同结果.

Carbohydrate Metabolism of the Cabbage White Butterfly(Pieris rapae L.)During Diapiause

The present study deals with the carbohydrate metabolism of Pieris rapae during diapausce. The result showed that the haemolymph carbohydrates of the diapausing pupae were mainly composed of trehalose and sorbitol. It was found that trehalose concentration increased abruptly at the time of initiation of diapause and remained at relatively high levels throughout diapause. The pattern of sorbitol was quite different from that of trehalose in that a delayed appearance of sorbitol for- llowed by its subsequent steady accumulation occurred late in diapause and was undetectable at the termination of diapause. The glycogen concen- tration fluctuated in a manner inversely related to those of trehalose and sorbitol, suggesting that an interconversion between glycogen, treha- lose and sorbitol took place throughout diapause. It was worth noting that the changes in trehalose coacentration were independent of temperature. The time at which the sorbitol appeared was the same at different temperatures, whereas the concentrations of sorbitol varied significantly. The results evidently demonstrated that the sharp rise in the concentration of trehalose was attributed to the initiation of diapause, and it could be regarded as a biochemical index of the onset of diapause. The process of sorbitol production seemed to be a time-dependent event, whereas the accumulation of sorbitol appeared to be temperature-dependent, with the lower temperture accelerating the synthesis of sorbitol. That the patterns of the haemolymph carbohydrates of the field overwintering pupae were similar to those reared in laboratory led to the speculation that trehalose and sorbitol were used as cryoprotectors for winter survival. Neither trehalose nor sorbitol accumulated in non-diapausing pupae, even if the pupae had been exposed to a low temperature for a long time.