Abstract: The study with field sampling method showed that in the Tibetan region of North westeon yunnan Province, the dominant groups of grassland insect community were Cicadelloidea, Miridae, Muscidae and Cecidomyiidae. The number of insect families on forage grassland, cultivated grassland, grazing grassland and shrub grassland were 40, 44, 35 and 36, and that of insect individuals were 1869, 1510, 997 and 848, respectively, indicating the higher richness and abundance of insect community on forage-and cultivatedgrasslands. The biodiversity index of cultivated grassland was also the highest. Based on the criterion of Jaccard’s ISJ, a medium similarity of insectcommunity was observed on the four grasslands. Different management patterns of grassland had definite effects on grassland insect community diversity, and traditionally managed forage grassland was benefited to the maintenance of this diversity.

Key words: Red tide, Photosynthesis, Growth, Prorocentrum minimum, Zinc limitation