Study On The Food Adaptability Of Dominant Grasshopper In Inner Mongolia Steppe

Temporal, spatial and trophic niches of grasshoppers are dependent on the structure of plantcommunity and food preference of grasshoppers. Articial and natural feeding experiments were used todetermine the feeding characters of grasshoppers, amount of ingested plants in grasshopper's crop wereanalyzed using RT-PCR. The results are as follows.1) The standard and method of extracting and storage of grasshopper crop were established. Basedon the ITS of rDNA and5.8s gene sequences of six plants, Stipa krylovii, Leymus chinensis,Cleistogenes squarrosa, Caragana microphylia, Artemisia frigida, and Salsola collina, special primers,fit to SYBR Green I, were designed in those plants. Standard curve for quantitative detection of theamount of plants ingested by grasshopper was also established. The relationship of the copies of ITSand the weight of contents in crops was determined by feeding six kinds of host plants to Oedaleusasiaticus and Dasyhippus barbipes and analyzing plant contents in crops with RT-PCR.2) Grassland community structure could affect the community of grasshopper. Canonicalcorrelation analysis showed that there was a positive correlation (r=0.955,P <0.05) between thecomprehensive factor of grasshopper and the comprehensive factor of host plant. Density of dominantgrasshopper species depended on dominant host plant speices. There was positive correlations betweenbiomass loss of L. chinensis and relative abundance of D. barbipes in sample plot one, between biomassloss of S. krylovii and relative abundance of O. asiaticus in sample plots two and three. RT-PCR showedthat D. barbipes prefered Leymus chinensis. The width of trophic niches of D. barbipes and O. asiaticuswas0.224and0.207, respectively; the former overlapping the latter by0.115and the latter overlappingthe former by0.125, which suggests that there is food competition in these two grasshopper species.3) Orthogonal test was employed to analyze the effects of density of O. asiaticus, D. barbipes andAngaracris barabensis and sample plot structure on mortality and food ingestion of the grasshoppers.The results showed that the two most important factors that affected grasshopper mortality weregrassland structure and population density of grasshopper, and the two most important factors that affectfood ingestion of grasshoppers were grassland structure and population density of other grasshopperswith high level of trophic niche overlap.