凹唇壁蜂滞育后阶段过冷却能力及生化物质动态变化

The super-cooling ability and biochemical substances of post-diapause Osmia excavata Alfken

【目的】凹唇壁蜂Osmia excavata Alfken是我国北方果树的主要授粉昆虫,发挥着重要的传粉增产生态服务功能。掌握其滞育后阶段抗寒性特点,并从生理生化水平上探讨耐寒机制,对于凹唇壁蜂的保护与利用具有重要意义。【方法】本文系统测定了滞育后阶段及出茧后凹唇壁蜂雌蜂、雄蜂的过冷却点、冰点,自由水、脂肪、蛋白质、海藻糖含量,过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、乙酰胆碱酯酶(AchE)的活性。【结果】凹唇壁蜂雌蜂、雄蜂的抗寒性差异不大,滞育后阶段过冷却点和冰点在出茧前逐渐升高、出茧后降低。其中,出茧日凹唇壁蜂雌蜂、雄蜂的过冷却点、冰点最高(抗寒性最低),分别为﹣12.35℃、﹣9.98℃和﹣12.63℃、﹣8.91℃。在滞育后阶段雄蜂脂肪含量显著高于雌蜂,雌蜂的蛋白质含量显著高于雄蜂,出茧后雄蜂的脂肪含量均迅速下降,雌蜂的蛋白含量迅速下降。出茧前,雄蜂的超氧化物歧化酶、过氧化氢酶、乙酰胆碱酯酶酶活性高于雌蜂;出茧后,雌蜂的酶活显著升高。在滞育后阶段,凹唇壁蜂雌蜂、雄蜂体内的海藻糖均呈显著降低趋势,出茧日雌蜂的海藻糖含量比茧后190 d下降了64.5%。【结论】滞育后阶段凹唇壁蜂有较强的抗寒性。在出茧前抗寒性逐渐降低,出茧后抗寒性升高。海藻糖代谢可能是凹唇壁蜂滞育后阶段能量消耗的重要途径。雄蜂的个体较小,但是有比雌蜂功能更强的抗氧化系统。

[Objectives] Osmia excavata Alfken is the major pollinator of fruit trees in north China where it provides the key ecological services of pollination and promoting fruit yield. Clarifying the cold-resistance of the post-diapause stage, and the physiological and biochemical mechanisms of cold-resistance, are important for the conservation and utilization of this species. [Methods] We systematically measured the super-cooling and freezing points, water content, fat content, protein content, trehalose levels, and the activity of catalase(CAT), superoxide dismutase(SOD) and acetylcholin esterase(AchE), in postdiapause and post-eclosion female and male O. excavata. [Results] There was no significant difference in cold resistance between the sexes. Supercooling and freezing points gradually increased, then decreased, after eclosion in post-diapause individuals. The supercooling and freezing points of females and males were highest after eclosion;﹣12.35 ℃, ﹣9.98 ℃and ﹣12.63 ℃, ﹣8.91 ℃, respectively. Post-diapause males had significantly more fat than females but females had significantly more protein than males. The fat content of males and the protein content of females decreased rapidly after eclosion. Before eclosion, the activity of superoxide dismutase, catalase and acetylcholinesterase were higher in males than in females. However, enzyme activity in females increased significantly after eclosion. Trehalose levels in both sexes decreased significantly post-diapause and trehalose levels in males on the day after eclosion were 64.5% lower than those on the 190 thday after cocooning. [Conclusion] Post-diapause O. excavata have strong cold-resistance. Cold resistance decreases gradually before eclosion but increases after eclosion. Trehalose metabolism may be an important energy consumption pathway in post-diapause O. excavata. Males are smaller, but have stronger antioxidant systems, than females.