甘薯天蛾过冷却点变化与生化成分的关系

Relationship between the supercooling point and the biochemical componens of Agrius convolvuli

测定长沙地区甘薯天蛾Agrius convolvuli L.在发育过程中不同时期的过冷却点、虫体水分和粗脂肪含量，并对其动态变化和相互之间的相关性进行分析。结果表明：不同世代甘薯天蛾过冷却点均随发育进程显著升高，在蛹期明显下降；2龄幼虫的过冷却点均为-11℃左右，蛹的过冷却点在越冬代过冷却点为-7.38℃，比其他世代蛹低2-3℃。甘薯天蛾虫体含水量随发育进程不断降低，粗脂肪含量则不断升高，其越冬代蛹粗脂肪含量占其干重高达30.23％。甘薯天蛾过冷却点与虫体水分含量呈正相关；而与虫体粗脂肪含量呈负相关，且在第2、3代和越冬代均呈显著负相关。甘薯天蛾在发育过程中通过调节水分和粗脂肪含量可能是其抵抗低温的生理机制之一。

The supercoling point, body water and crude fat content in different development stages of sweet potato sphinge, Agrius convolvuli L., in Changsha, Hunan Province were tested, and the relationship between the supercooling point and body water and crude fat content was analyzed. The results showed that the mean supercoling point of larvae increased with the instar increasing, but the mean supercoling point of pupae decreased. It was found that the mean supercoling point of the 2th instar larvae in all generations was about -11℃, and that of overwintering pupae was -7.38℃, which was lower than the pupae in other different generation. The mean body water content showed decreasing tendency with the development of sweet potato sphinge, and a reverse tendency for the crude fat content. The mean crude fat content of overwintering pupae was 30.23% of its dry body weight. There was positive relationship between supercoling point and body water content, and negative relationship between supereoling point and crude fat content. The results indicated that adjusting body water and crude fat contents in the development may be one of important physiological mechanisms for sweet potato sphinge cold hardiness.