| Oedaleus asiaticus was widely distributed over the Eurasian Steppe with a strong ecological adaptability, and caused great damage to the grassland. The the occurrence and outbreak of O. asiaticus are closely related to habitat change infulanced by human activity and climate change. To clarify the habitat suitability and adaptability characteristics of O. asiaticus to different habitats in Inner Mongolia steppe, we studied the population characteristics in different habitats and adaptation mechanisms in the field by RNA seq and qPCR. The results are as follows:Community structures were simulated by different compositions of Stipa krylovii, Leymus chinensis, Arternisia frigida. The biology, ecology evidence indicated that the grasshoppers showed certain preferences to specific plant, there showed a significantly negative correlation between the dietary selectivity index and the proportion of specific plant under the plant composition change. Results indicated that the generalist grasshopper O. asiaticus varied in its preferred plants and the level of preference, but maintained a species-specific dietary structure with different plant compositions. The consumption of S. krylovii was largest, followed by L. chinensis, A. frigida. The proportion of food consumption are S. krylovii 50.0 ± 6.56%, L. chinensis 37.6 ± 5.93%, A. frigida 12.3 ± 2.56%. Body size in mixed diets grew larger than in single-plant diets. Evidence suggests that food availability of specific plants are the key factors for grasshoppers to maintain a specific dietary structure(P < 0.05). There showed a significant negative correlation between trophic niche and total biomass, which was in accordance with the optimal feeding strategy. There are significant differences in the proportion of L. chinensis and A. frigida in its dietary structure between females and males. The feeding proportion of L. chinensis in females was significantly higher than the proportion of A. frigida(P < 0.05), the feeding proportion of A. frigida in males was significantly higher than the proportion of L. chinensis(P < 0.05). And there showed a significant positive correlation between the ratio of A. frigida and male weight(P < 0.05). These indicated that niche differentiation between sexes in O. asiaticus was existed.In typical grassland under different habitats, the viability of grasshopper populations was reflected by phenotype plasticity characteristics. Grasshoper population mortality was significantly lower in Af habitats than other habitats(P < 0.05). Across all four treatments, both female body length and body mass were negatively correlated with plants density(for body length, r =-0.56, P = 0.0211, body mass, r=-0.54, P = 0.0154). Development time was negatively correlated with Shannon-Weiner index(r =-0.48, P = 0.0304), but it was positively correlated with both plants density(r =0.43, P = 0.0579), and plant biomass(r =0.43, P = 0.0582). The inconsistencies of habitat suitability and food suitability indicated that food resources are an important factor affecting the grasshoppers’ habitats suitability, however, the plant community factor in habitats also played a decisive role in affecting the viability of grasshopper.Transcriptome revealed that the response to different habitats and plant species were mainly affected by the community structure. Compared with the grasses dominant habitat, grasshoppers in Af habitats were significantly down-regulated the numbers of genes in basic sugars metabolism, amino acids metabolism, proteins metabolism, energy metabolism, etc. The FPKM of insect cuticle proteins, peritrophin-1, and β- glucosidase / phlorizin hydrolase showed significant differences in four different habitats. Correlation analysis, regression analysis showed that peritrophin-1, β- glucosidase / phlorizin hydrolase expressed highest in Sk habitats, showing a negative correlation with plant biodiversity(P < 0.05). The expression of insect cuticle protein was highest in Lc habitats, and showed a negative correlation with the grasshopper body length, body weight, and developmental duration, and a positive correlation with plant density(P < 0.05).Quantitative PCR revealed that the expression of arginine kinase(AK), adenosine monophosphate-activated protein kinase(AMPK), aldehyde dehydrogenase(ALDH), and vitellogenin(Vg) were related to the viability of grasshopper. There showed a significantly negative correlation between the relative expression levels of AK and survival(P < 0.05), there showed a significantly positive correlation between Vg expression and survival rate(P < 0.05), the relative expression AMPK, ALDH was negatively correlated to the development rate(P < 0.05). The relation between genes and grasshopper growth development can further be used to predict and evaluate the viability and resistance of grasshopper. |
PDF Full Text Request