Abstract:  In this study, seasonal variation in cold tolerance of Harmonia axyridis adults were investigated by measuring their supercooling point (SCP), water content, total fat content and cold survival ability. The results indicated that cold tolerance of the adults varied obviously  with seasons. The pre-winter adults had higher tolerance to low temperature than the summer and post-winter adults. Summer adults with cold acclimation (5℃, 5 d) before the occurrence of low temperatures showed higher cold tolerance. The SCPs and the water and fat content of the female and male adults varied remarkably in different seasons. The SCPs of female and male adults were highest in July (-7.6℃ and -8.0℃, respectively) while lowest in January (-18.1℃ and -16.9℃, respectively); the water contents of female and male adults were highest in September (66.87% and 68.01%, respectively) while lowest in February (52.94% and 51.53%, respectively). The SCP and water content of over-wintering adults were significantly lower than those in other seasons. But the total fat contents of pre-winter female and male adults (50.07% and 47.93%, respectively) were significantly higher than those in other seasons

Key words: Harmonia axyridis, cold tolerance, cold acclimation, supercooling point (SCP), water content, total fat content