【目的】 玉树蝠蛾Hepialus yushuensis是青海省冬虫夏草主产区优势寄主昆虫，主要分布在海拔3 000-5 000 m的高寒草甸，该区域年平均温度不足5 ℃。通过对玉树蝠蛾幼虫体内糖类物质含量和关键酶活性的分析，探讨冬虫夏草寄主蝠蛾的高寒适应性机制。【方法】 以玉树蝠蛾幼虫4龄幼虫为研究对象，分析蝠蛾幼虫在温度为5、15和25 ℃的条件下，分别处理1、2和4 h后体内的糖原、果糖、海藻糖和山梨醇4种糖类物质含量的变化，以及海藻糖酶、3-磷酸甘油脱氢酶和3-磷酸甘油醛脱氢酶活性的变化。【结果】 低温（5 ℃）条件下玉树蝠蛾幼虫体内糖原含量显著低于对照处理（15 ℃）（P<0.05），高温（25 ℃）条件下玉树蝠蛾幼虫体内糖原含量显著高于对照处理（15 ℃）（P<0.05）。玉树蝠蛾幼虫体内海藻糖、果糖和山梨醇含量在低温（5 ℃）条件下均呈现一定的增加趋势，而在高温（25 ℃）条件下均呈一定的下降趋势。低温（5 ℃）条件下海藻糖酶活性显著低于对照处理（15 ℃）（P<0.05），而在高温条件下（25 ℃），海藻糖酶活性显著高于对照处理（15 ℃）（P<0.05）。5 ℃处理一定时间后玉树蝠蛾幼虫体内3-磷酸甘油脱氢酶和3-磷酸甘油醛脱氢酶活性均显著高于对照处理（15 ℃）（P<0.05），这表明玉树蝠蛾幼虫通过调控体内有氧代谢和糖酵解代谢水平，加快糖原等糖类物质转化为小分子抗寒物质以提高虫体的抗寒能力。【结论】 玉树蝠蛾幼虫体内糖原的分解与3种单糖和糖醇含量的增加密切相关，与糖类物质代谢相关的3种关键酶活性的变化趋势同4种糖类物质的变化趋势相吻合，玉树蝠蛾幼虫体内糖代谢过程受到海藻糖酶、3-磷酸甘油脱氢酶和3-磷酸甘油醛脱氢酶的调控。

[Objectives]  To analyze the carbohydrate content and the activity of key carbohydrases in Hepialus yushuensis larvae, the dominant host of Cordyceps sinensis in the main C. sinensis producing areas of Qinghai province, in order to investigate the mechanism underlying adaptation of H. yushuensis larvae to the Tibetan Plateau’s cold environment where they are predominantly found in alpine meadows at an altitude of 3 000-5 000 m and an annual average temperature of < 5 ℃. [Methods]  4^th instar larvae of H. yushuensis were randomly assigned to one of three treatment groups which were kept at temperatures of 5, 15 (control), or 25 ℃ for 1, 2, or 4 hours. At the end of each experiment, the glycogen, fructose, trehalose and sorbitol content of larvae, and their trehalase, glycerol 3-phosphate dehydrogenase and glycerol 3-phosphate dehydrogenase activity, were measured. [Results]  Glycogen content was significantly lower in the 25 ℃ treatment group, than the 15 ℃ control group (P<0.05). Trehalose, fructose and sorbitol content were higher in the 5 ℃ treatment group than in the 25 ℃ group (P<0.05). Trehalase activity was significantly lower in the 5 ℃ treatment group, and significantly higher in the 25 ℃ group, than in the control group (P<0.05). Glycerol 3-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase activity were significantly higher in the 5 ℃ group than in the control group (P < 0.05), indicating that low temperature may accelerate conversion of glycogen and other sugars into smaller, cold-resistant substances to improve cold-tolerance. [Conclusion] Glycogen catabolism in H. yushuensis larvae appears to be closely related to increased monosaccharide and sugar alcohol content. The tendency for catalytic alterations of three key carbohydradases is consistent with observed changes in 4 kinds of carbohydrates. The carbohydrate metabolism in H. yushuensis larvae is regulated by trehalase, glycerol 3-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase.