Abstract: In this study, cold hardiness of pupae and over-wintering adults among seasonal populations and geographic populations of Bactrocera dorsalis (Hendel) in China were assayed by measuring their supercooling capacity and cold survival ability. The results showed that cold tolerance of the pupa followed strong seasonal rhythm: the pre-winter population had higher tolerance to low temperature than the summer population; and the summer population completely collapsed as exposed to 0℃ for 2 days, but there was still 61.4% survivorship for the pre-winter population. The SCPs of one day-old pupae had significantly difference among the different months, highest in February (-9.26℃) while lowest in August (-15.20℃). Further analysis showed that there was a big variation range of SCPs among individuals, which were gathered around two points: -15℃ and -6℃. There was no significant difference in cold hardiness among five geographic populations of B. dorsalis. The main factors that influence cold hardiness of natural populations of B. dorsalis were discussed combined with the results obtained this study.  

Key words: Bactrocera dorsalis, natural population, cold hardiness, pupa, over-wintering adult