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The Northeast area plays an important role in grain production in China,and 25-30%of total national grain output is from this region.According to incomplete statistics,the amount of crop damaged by rodents is billions of tons per year.However,there are very few reports and studies about rodent pests in this agricultural system.In a four-year survey,we found that rodent pests showed a high density in Northeast China,in one year the total number of captured rodents per hundred trap nights reached 16,and increased from 2010 to 2013.Eight rodent species including Rattus norvegicus,Mus musculus,Cricetulus barabensisi,Apodemus agrarius,Tscherskia triton,Microtus maximowiczii,Apodemus speciosus and Clethrionomys rutilus were captured.Apodemus agrarius was the dominant species in each survey.Seasonally,rodent density was about three times higher in autumn than in spring.Spatially,areas with the highest density of rodents were the edges of farms,or adjacent tree belts.More rodents were captured from maize fields than from rice and soybean fields.We also surveyed the management effectiveness of OTBS (Opened Trap-barrier system) ,which was modified and improved from traditional TBS according to the local agricultural characteristics.OTBS had the same efficiency in rodent capture compared with TBS,and resulted in rodent density decreases during three successive years of use.