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[目的]降水和放牧是驱动草原蝗虫发生的重要因素,但其如何发挥作用尚存在争论.本文研究放牧和季节性降水增加的耦合效应通过改变栖息环境中食料植物的养分含量来驱动草原蝗虫灾害发生的生理与生态学机理.[方法]在野外设置放牧和季节性增加降水的交叉处理,利用室外笼罩和室内饲养的方法研究在不同放牧和降水处理下毛足棒角蝗Dasyhippus barbipes发育与存活的响应规律,分析放牧和季节性降雨量变化耦合对毛足棒角蝗发生程度的影响.[结果]放牧极显著地(P0.05).放牧会极显著地(P0.05).[结论]适当放牧会降低植物中可溶性糖态C,增加氨基酸态N的含量,有利于毛足棒角蝗的生长、发育、存活,促进毛足棒角蝗种群发生.“,”[Objectives] Precipitation and grazing are important factors that drive grasshopper outbreaks in grassland ecosystems but exactly how these factors affect grasshopper population dynamics remains controversial. To clarify this, we studied the combined effects of sheep grazing and seasonally increasing precipitation on variation of both total C and N content, and available C and N content, of grasshopper food plants. [Methods] Using both field studies and laboratory experiments, we investigated the development and survival responses of D. barbipes under different grazing and precipitation treatments. [Results] Grazing can significantly decrease the C content in soluble sugar, and the available C content of the leaves of Leymus chinensis, but did not significantly affect the C content of starch or total C. Grazing also significantly increased the N content of amino acids, available N, total N, and the available C : N ratio. However, it had no significant effect on the N content of protein. The effect of seasonally increasing precipitation on C and N varied between grazed and ungrazed treatments. Increasing precipitation tended to reduce the C content of soluble sugar and the N content of amino acids, but the differences among precipitation treatments were not significant. Moreover, the results of a laboratory experiment suggest that grazing significantly decreased mortality, shortened developmental duration, increased growth rate, and increased adult body weight of fifth instar nymphs to adults, whereas the results of a cage experiment conducted in the field indicate that grazing increased survival and the development rate. Nevertheless, increasing precipitation did not significantly affect any biological parameters of D. barbipes. [Conclusion] Suitable grazing was propitious to the growth, development, survival of D. barbipes, and could promote grasshopper outbreaks by decreasing the C content of soluble sugar and increasing the N content of amino acids in food plant leaves.