小胸鳖甲各龄期幼虫过冷却点的测定

Analysis and Comparison of the Supercooling Point in Larvae of Microdera punctipennis

【目的】了解新疆荒漠甲虫准噶尔小胸鳖甲幼虫耐寒性的发育阶段性变化。【方法】对新疆荒漠甲虫准噶尔小胸鳖甲各龄期幼虫的过冷却点进行测定。【结果】同一虫期个体间的过冷却点出现不同程度的变异,但均服从正态分布。不同虫期的过冷却点差异显著,其中1龄的过冷却点最低(-19.4～-24.1℃),且个体差异不大。老熟幼虫的过冷却点个体差异较大,其中7龄幼虫中过冷却点在个体间差异达到15.7℃(-5.6～-21.3℃)。【结论】老龄幼虫最有可能是该虫在荒漠环境地区越冬的虫态。

[ Objective ] In order to understand the cold hardiness of the larvae of Microdera punctipennis, an endemic species in Xinjiang desert region, at different developmental stages, changes of the supercooling point （SCP） among the instars were investigated and compared so as to predict the overwinter/ng stage of this beetle. [ Method ] The supercooling point of all the seven instars of M. punctipennis were measured and statistically analyzed in the view point of the variation and frequency distribution of SCP. [ Result]The results indicated that the SCP of M. punctipennis instars varied significantly among different individuals of the same instars, but followed a normal distribution. The SCP at the 1st instar ranged from - 19.4~C to - 24. I^C which was the lowest variation among all the larvae developmental stages, and the difference among individuals is small. Values of SCPs varied significantly in eider instars. The difference between the highest and the lowest value was 15.7℃ （ - 5.6 - - 21.3℃ ） in the 7th instars. [ Conclusion] The results suggest that, except the adult, M. punctipennis may overwinter in the desert environment in a small portion of the old instars.