Abstract: 【Aim】 This study aims to explore the cold tolerance strategies and overwintering stage of Athetis dissimilis (Hampson). 【Methods】 The supercooling point (SCP), freezing point (FP), and the contents of water, fat, protein, glycerin, sorbitol and trehalose in the 3rd, 4th, 5th, 6th instar and mature larvae, and pupae of A. dissimilis were measured in the laboratory. 【Results】 The SCP and FP had obvious differences among different instar larvae of A. dissimilis, and the SCP and FP of young larvae were higher than those of old larvae. The SCP and FP of mature larvae dropped to the lowest (-18.20℃ and -11.72℃, respectively). There were significant differences in the contents of biochemical substances between different instar larvae. The water and glycerin contents declined with the increase of developmental stage. The lowest water and glycerin contents were found in pupae (65.33% and 154.90 μg/mg, respectively). There was a trend of increase of fat and protein contents with the increase of developmental stage. The fat and protein contents in pupae (25.36% and 2 298.37 μg/mg, respectively) were higher than those in larval stages. The trehalose content in mature larvae was relatively high (57.28 mg/g), while the sorbitol content was relatively low (15.49 mg/g). 【Conclusion】 The strongest two cold-tolerant stages of A. dissimilis were mature larva and pupa, which may be more suitable for overwintering than other developmental stages. Fat, protein and trehalose may be the important cold-resistant substances in A. dissimilis.

Key words: Athetis dissimilis, overwintering stage, cold tolerance, cold-resistant substances, supercooling point