Abstract: [Objective] To assess the effects of different degrees of human disturbance on the occurrence dynamics of locusts on grasslands, and to provide references for grassland pest control.[Method] From May to August in the year of 2018, 3 investigation sample plots with mild, moderate and severe disturbance were set up in Xinghuo pasture, Yinlang pasture and Hongji pasture in Ranghulu District of Daqing City of Heilongjiang Province, respectively, to assess the locust species, common species, population densities and population variations with time. The locust population densities were investigated by quadrat method with insect three-dimensional mesh enclosures and quadrat frame. The combination of quadrat frame sampling and sweep net sampling methods were used in the species surveys which were carried out once a week with a total of 12 times.[Result] A total of 11 species of locusts were observed in the 3 investigation sample plots, and Oxya chinensis was the dominant species in the grasslands with different degrees of disturbance. The common species were Oxya chinensis, Dasyhippus barbipes, Pararcyptera microptera meridionalis, Epacromius coerulipes, Chorthippus albomarginatus, Acrida cinerea, Haplotropis brunneriana Saussure and Oedaleus infernalis Saussure. The species numbers of locusts in grasslands with severe, moderate and mild disturbance were 9, 10 and 10, respectively. The total population densities of locusts were in the order of severe disturbance （5.10 heads/m²） > moderate disturbance （4.66 heads/m²） > mild disturbance （3.37 heads/m²） with significant differences （P<0.05）. The population densities of Oxya chinensis, Epacromius coerulipes, Pararcyptera microptera meridionalis, pygmy grasshoppers and Oedaleus decorus asiaticus among the grasslands with different degrees of disturbance were significantly different （P<0.05）. From May to August, the locust population densities increased first and then decreased, and the presence of peak phase of locust population densities in grassland with severe disturbance was earlier than that in grassland with moderate and mild disturbance.[Conclusion] The dominant species of locusts in grasslands in Daqing City with three degrees of human disturbance is Oxya chinensis. Mild disturbance can significantly reduce the locust population densities and delays the arrival time of the peak phase of locusts number in grassland.

Key words: locusts, population density, human disturbance, grassland