Diet Composition and Trophic Niche of Main Herbivores in the Typical Steppe of Inner Mongolia Study on the diet composition and trophic niche of main herbivores in the Inner Mongolia Typical steppe——Taking Leymus chinensis community as an example Sequence Analysis of mtDNA COⅠ Gene and Relationships of Geographical Populations of Oedaleus asiaticu in Inner Mongolia Nocturnal Migration of Grasshopper(Acrididae:Oedaleus asiaticus) Sequence analysis of mtDNA ND6 and fragments of flanking genes from nine geographical populations of Oedaleus asiaticus in Beijing and surrounding regions