Supercooling Point Shift of Pea Leafminer Pupae with Latitude and Its Implication for the Population Dispersion

The pea leafminer Liriomyza huidobrensis is an invasive species,which has widely distributed in China.To specify its adaptation to cold (stress),we sampled pupae and larvae of the species from Kunming,Chengdu,Xian,Beijing and Chifeng,stepping up about every 5° from south to north.Supercooling points (SCP) of pupae were experimentally tested.The SCP increased with latitude,and the difference between populations at the two extremes was 3.7℃,and the SCP was negatively related to the yearly margin of ambient temperature for the geographical populations,but not to the monthly or yearly temperatures they experienced.The results imply that an adaptive course of lowing SCP involves in the species dispersing northwards.