低温胁迫对沙葱萤叶甲幼虫过冷却能力及生长发育的影响
Effects of low temperature stress on the supercooling capacity and development of Galeruca daurica Joannis larvae(Coleoptera: Chrysomelidae)
李 浩1** 周晓榕1 庞保平1*** 张卓然2 常 静1 单艳敏2
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DOI：10.7679/j.issn.2095-1353.2015.048
作者单位：1. 内蒙古农业大学草原昆虫研究中心，呼和浩特 010019；2. 内蒙古草原工作站，呼和浩特 010020
中文关键词：沙葱萤叶甲，低温胁迫，发育历期，存活
英文关键词：Galeruca daurica, low temperature stress, developmental duration, survivorship
中文摘要：【目的】 低温是影响昆虫生长发育和存活的关键因子之一。通过研究低温胁迫对沙葱萤叶甲Galeruca daurica Joannis幼虫过冷却能力及生长发育的影响，为进一步预测其种群动态及分布范围奠定必要的基础。【方法】 在室内，沙葱萤叶甲1龄幼虫经不同的低温处理后，测定其过冷却点及后期幼虫和蛹的发育历期及存活率。【结果】 快速冷驯化对1龄幼虫的过冷却点存在极显著的影响，其中在﹣10℃下处理2 h后的过冷却点显著低于对照，而在﹣6℃下处理2 h后与对照无显著性差异。经低温处理存活的1龄幼虫在25℃下继续饲养至蜕皮为2龄幼虫，测得的过冷却点与对照均无显著差异。1龄幼虫经历不同低温处理后，1龄和2龄幼虫发育历期和幼虫总发育历期与对照相比均显著延长；蛹期与对照相比差异不显著；短时低温处理（2 h）对3龄幼虫发育历期无显著影响，而较低温度（﹣5℃）的长时间（2~6 d）处理却显著缩短了3龄幼虫发育历期，但0℃处理对3龄幼虫发育历期影响不显著。低温处理对后期1龄和2龄幼虫死亡率存在显著的影响，但对3龄幼虫和蛹的死亡率影响不显著。通常在低温处理时间相同的情况下，胁迫温度越低，对后期幼虫发育历期和死亡率影响越大；在处理温度相同的情况下，胁迫时间越长，对后期幼虫发育历期和死亡率影响越大。【结论】 低温胁迫可以显著地提高沙葱萤叶甲幼虫的过冷却能力，但却延长了后期幼虫的发育历期及降低了其存活率，胁迫温度越低、时间越长，影响程度越大。
英文摘要：[Objectives] Low temperature is one of key factors affecting the growth, development and survivorship of insects. We investigated the effects of low temperature stress on the supercooling capacity and development of Galeruca daurica Joannis larvae in order to build an indispensable foundation for further forecasting its population dynamics and distribution. [Methods] We measured the supercooling points (SCPs), developmental duration and survival rates of larvae and pupae after first instar larvae had been subjected to different low temperature treatments in the laboratory. [Results] Rapid cold hardening significantly influenced the SCPs of first instar larvae. The SCP of larvae exposed to ﹣10℃ for 2 h was significantly lower than that of control larvae, whereas the SCP of larvae exposed to ﹣6℃ for 2 h was not. The SCPs of second instar larvae that had been subjected to low temperature treatment as first instars were not significantly different from those of the control. The developmental durations of the first and second instar larvae, and the overall larval developmental period, were significantly longer than those of the controls if first instar larvae had been subjected to low temperature. Cold treatment of the first instar, however, had no significant effect on the duration of the pupal stage. Short (2 h) low temperature (﹣5℃) treatments did not significantly affect the developmental duration of third instar larvae but longer (2-6 d) low temperature treatments did. Longer exposure to 0℃ did not affect developmental duration. Low temperature treatment significantly affected the death rates of first and second instars, but not of third instars and pupae. Generally, the lower the temperature and the longer the period of exposure, the longer the developmental duration and the higher the death rate of successive instars and pupae. [Conclusion] Low temperature stress can significantly enhance the supercooling capacity of G. daurica larvae but also prolongs development and reduces the survival rates of successive instars. The longer the period of exposure and the lower the temperature, the stronger the effect.