School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
Science. 2012 Jan 27;335(6067):467-9. doi: 10.1126/science.1214433.
Current paradigms generally assume that increased plant nitrogen (N) should enhance herbivore performance by relieving protein limitation, increasing herbivorous insect populations. We show, in contrast to this scenario, that host plant N enrichment and high-protein artificial diets decreased the size and viability of Oedaleus asiaticus, a dominant locust of north Asian grasslands. This locust preferred plants with low N content and artificial diets with low protein and high carbohydrate content. Plant N content was lowest and locust abundance highest in heavily livestock-grazed fields where soils were N-depleted, likely due to enhanced erosion. These results suggest that heavy livestock grazing and consequent steppe degradation in the Eurasian grassland promote outbreaks of this locust by reducing plant protein content.
目前的模式通常假设增加植物氮（N）可以通过缓解蛋白质限制、增加食草昆虫数量来提高食草动物的表现。然而，我们的研究结果却表明，与这种情况相反，宿主植物氮的富集和高蛋白人工饲料会降低亚洲飞蝗（一种北亚草原的主要蝗虫）的体型和活力。这种蝗虫更喜欢低氮含量的植物和低蛋白、高碳水化合物含量的人工饲料。在土壤氮素枯竭、可能由于侵蚀加剧的牲畜过度放牧的农田中，植物氮含量最低，蝗虫数量最多。这些结果表明，欧亚草原的过度放牧和随之而来的草原退化通过降低植物蛋白质含量，促进了这种蝗虫的爆发。
