| Oedaleus decorus asiaticus B.Bienko，the major northern grassland pest, is mainly distributed inthe Mongolian Plateau and surrounding areas, whose repeated outbreaks has caused serious disasters..O.asiaticus mainly feeding on grasses, and their nutritional needs incline to low-nitrogen plants. Inorder to clarify the feeding characteristics and nutritional needs of O.asiaticus, this study examines thefood adaptability and genes of energy metabolism. Results are as follows：This study examined the relationship between plants and O.asiaticus population structure in thedifferent habitats, and assayed effect of Leymus chinensis, S. krylovii (Stipa krylovii) on growth anddevelopment. The results indicate that the amount of O.asiaticus is negatively correlated with thecoverage of plant (r=-0.7708，P<0.01), and the biomass of plant (r=-0.9052, P<0.01).The diversity ofgrasshopper is positively correlated with the diversity of plant (r=0.5884, P<0.05). The amount of thegrasshopper is negatively correlated with the coverage of plant (r=-0.7593, P<0.01) and the biomassof plant (r=-0.8597, P<0.01). The consumption of O.asiaticus indoor is Leymus chinensis> Stipakrylovii (P<0.05). S. krylovii efficiency is higher than L. chinensis.By applying both the fields net and indoor independent feeding method, this study compared thevitality index of three groups of O.asiaticus with3population densities, and quantitatively analyzed theeffect of S.krylovii and L. chinensis on the growth and development of O.asiaticus.The result indicatsthat the relative growth rate of female, which feed on S.krylovii, is higher than those feed on L.chinensis (p<0.05). The relationship between the coverage of S.krylovii and the vitality value fits theexponent function (Y=0.355e0.0061x). When the coverage of S.krylovii is less than25%, the vitalityvalue increased slowly with the increase of the coverage. When the coverage is more than25%, thevitality value increased rapidly. The relationship between the coverage of L. chinensis and the vitalityvalue fits quadratic function (Y=0.0007x2-0.0346x+0.7819). When the coverage of L. chinensis is lessthan25%, the vitality value decreased with the increase of coverage. When the coverage is more than25%, the vitality value is positively related with the coverage. The vitality of O.asiaticus in S.kryloviiis better than in L. chinensis. The plant coverage and the population density are main factors to affectthe vitality of O.asiaticus.On the basis of gene sequence of the database, we design degenerate primer to amplicationO.asiaticus of4genes (AK, CREB, AMPK, Vg). affinis similarity is AK95%, CREB75%, AMPK75%, Vg41%. Homology of O.asiaticus is accordant with similarity, which indicated the genesequence is exist in O.asiaticus. We detected gene expression of different instar in different plots byquantitative PCR. The result showed that, the gene expression of O.asiaticus fed on S.krylovii ishigher than which fed on L. chinensis. On the base of gene expression and vitality value, the matchequation of correlationY=0.633X2-6.62271-4.6627X1+0.0033X22-0.2685X2+2E+09X3+187.9655, X1is AK, X2is CREB, X3isAMPK. When the gene copy number of AK is less than1.86×1016copies/μL, the vitality value decreased with the increase of the copy number. When the gene copy number is more than1.86×1016,the vitality value decreased slowly with the increase of copy number. The expression of AK is notcontinue to rise with environmental degradation. When the copy number of CREB is between2.21×1013copies/μL and1.72×1015copies/μL, the vitality value decreased with the increase of copynumber. When the copy number of AMPK is bwtween3.05×1012copies/μL and2×1013copies/μL, thevitality value decreased with the increase of copy number. The gene expression of CREB and AMPKcontinue to rise with environmental degradation, the gene expression of Vg is not obvious correlationwith environment. |
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