Abstract: Rapid cold hardening can enhance the cold tolerance of some insects. To explore the effects of different cold hardening induction temperature on the cold tolerance of Arma chinensis and related physiological mechanisms, the 3rd generation A. chinensis adults reared indoor were treated with cooling at 15, 10, and 4 ℃ for 4 h, respectively, or with gradual cooling from 15 ℃ for 4 h to 10 ℃ for 4 h, and finally to 4 ℃ for 4 h. The super-cooling point, water content, and the contents of low molecular carbohydrates, glycerol, and amino acids of the adults after cooling and the adults cold tolerance at 0, -5, and -10 ℃ were measured by thermocouple, high performance liquid chromatography, and other analytical techniques. When exposed at -10 ℃ after cooling, the survival rate of the adults treated with gradual cooling or treated with cooling at 4 ℃ for 4 h was averagely 58.3%, while that of the adults reared at room temperature (25 ℃±2 ℃) or treated with cooling at 15 ℃ or 10 ℃ for 4 h decreased significantly, with an average of 8.9%. The super-cooling point of the adults treated with gradual cooling or with cooling at 4 ℃ for 4 h was -15.6 ℃, which was averagely 1.3 ℃ lower than that of the other treatments. The water content of the adults had no significant difference among all treatments, with an average of 61.8%, but the glucose, sorbitolum, glycerol, Ala, and Glu contents in treatments gradual cooling and cooling at 4 ℃ for 4 h increased by 2.82-fold, 2.65-fold, 3.49-fold, 51.3%, and 80.2%, while the fucose, mannose, and Pro contents decreased by 68.4%, 52.2%, and 30.2%, respectively, as compared with the other treatments. The fructose content showed no significant difference among all treatments. It was suggested that rapid cool hardening had a critical temperature to induce the physiological metabolism process of adult A. chinensis, and gradual cooling hardening could not further increase the cold tolerance of adult A. chinensis on the basis of rapid cool hardening.

Key words: Arma chinensis, rapid cold hardening, cold tolerance, physiological mechanism