Effects of altitude and ice nucleating active bacteria on the super-cooling point of Evergestis extimalis Scopli (Lepidoptera: Pyralidida).

[Objectives] To understand how cold tolerance is influenced by altitude and ice nucleating active bacteria (INA) in high altitude environments. Methods: Field conditions were simulated in a laboratory to study the effects of varying the super-cooling point (SCP) and freezing point (FP) of Evergestis extimalis.Results: Super cooling point declined gradually with altitude. For example, the SCP of E. extimalis from Le Du (1 900 m ASL), Xing Ning (2 300 m ASL) and Huang Yuang (3 010 m ASL) were 12.30, 13.39 and14.56, respectively. Variation of SCP and freezing point were correlated with local temperature. The SCP of E. extimalis increased after INA treatment. E. extimalis in the following treatment groups; INA1-1 (Pseudomonas syringae), INA2-1 (P. syringae), INA3-1 (Erwinia pyrifoliae) and the control, had SCPs of -10.72, -13.73, -14.04 and -14.39, respectively in Feb. 2014. Mortality in the INA1-1, INA2-1, INA3-1 treatment groups and the control were 29.09%-36.17%,33.16% and 27.44%, respectively on Nov. 2013.Conclusion: The SCP of E. extimalis decreased with increasing altitude. INA treatment dramatically reduced mortality and increased the SCP of E. extimalis. [ABSTRACT FROM AUTHOR]