Abstract: 【Aim】 This study aims to investigate the cold tolerance and cold hardiness strategies of Ceroplastes japonicus Green in different overwintering stages (before， during and after overwintering). 【Methods】 The supercooling point (SCP) and freezing point (FP) of C. japonicus before overwintering (October)， during overwintering (January) and after overwintering (April) were measured with thermocouple method， and the contents of body water， fat， glycerol， total sugar， glycogen and trehalose were examined with physiological and biochemical methods. 【Results】 The SCP and FP of C. japonicus during overwintering were the lowest (-13.74℃ and -10.13℃， respectively)， significantly different from those after overwintering (-11.88℃ and -7.12℃， respectively)， but with no difference from those before overwintering (-13.30℃ and -9.95℃， respectively). The body water contents of C. japonicus before， during and after overwintering were 28.84%， 11.28% and 29.60%， respectively. The body water contents before and after overwintering had no difference， but were significantly different from that during overwintering. The fat contents before overwintering (86.38%) and during overwintering (85.77%) had no difference， but were significantly different from that after overwintering (77.63%). The glycerol content had no significant difference in the three stages. The total sugar contents before overwintering and during overwintering were significantly higher than that after overwintering. The glycogen contents before， during and after overwintering were 4.03， 5.45 and 1.76 μg/mg， respectively， with significant difference among the three stages, and the glycogen content decreased significantly after overwintering. The trehalose content before overwintering was the highest (14.72 μg/mg)， significantly different from those during overwintering (6.85 μg/mg) and after overwintering (7.92 μg/mg)， but with no significant difference between during overwintering and after overwintering. 【Conclusion】 The results revealed the cold hardiness of C. japonicus in different overwintering stages， as well as the changes in contents of cold hardinessrelated substances，  and would provide the basis for evaluating the low temperature adaptation， geographical distribution and population dynamics of C. japonicus.

Key words: Ceroplastes japonicus, overwintering, cold hardiness, supercooling point, biochemical substances, low temperature adaptation