Abstract: Based on the data of long-term field surveys and various literature records, the ecofaunas of Acridoidea in the following seven vegetational zones (or subzones) of Inner Mongolia region of China were expounded: Bright coniferous forest zone of cold-temperate type (F1), Deciduous broadleaf forest zone of mid-temperate type (F2), Forest steppe zone (FS), Typical steppe zone (TS), Desert steppe zone (DS), Steppe desert subzone of warm-temperate type (SD) and Typical desert subzone of warm-temperate type (TD). The zonal characteristics of specific compositions of Acridoidea fauna, the ecological conditions (vegetation, climate and soil etc.) in each zone, and the ecological mechanisms in formation of these different specific compositions were analyzed. The species diversities of acridoids and the zonal diversification of faunal geographic elements in different zones, and their relationships with different vegetation in each zone were also summarized and compared. The results indicated that the TS sustained the highest species diversity of acridoids since it could supply acridoids with sufficient temporal, spatial and trophic niches. In food selection acridoids favor mostly ants of Gramineae and Compositae, and both the “perennating rosette grass" and “root stock grass" were just right the dominant components of plant communities in the TS, and then the acridoids in this zone could get the most diverse temporal, spatial and nutritional niches with rich foods, diverse habitats, abundant sunshine and suitable soil for egg laying. In contrast, the two vegetational zones of F1 and TD in Inner Mongolia Region all possessed relatively lower species diversity and quite different compositions of acridoids. And this may be caused by the extreme climatic conditions (lower temperature with high humidity in F1 and high temperature with lower humidity in TD) that restricted the occurrence and distribution of acridoids in both zones. It is inferred that the modern status of the acridoid ecofaunas in Inner Mongolia Region is the combined result of both natural selective stress to acridoids and their adaptive evolution in the long course of natural history.

Key words: Acridoidea, ecofauna, vegetational zone, fauna geographical component, Inner Mongolia Region