Characteristics and reasons of the outbreak of the brown planthopper Nilaparva ta lugens in Anqing in 2006

Abstract：       The main characteristics of the outbreak of brown planthoppers，Nilaparvata lu gens Stal in Anqing in 2006  included large amount of immigrant pests with obvious immigration peaks, earlie r occurrence of shortwinged adults with large amount, rapid increasing of fiel d population, great occurrence all over the city, breaking out in parts of city,  and significant difference of population size among field patches. Based on the  above, the main reasons of the outbreak of brown planthoppers were analyzed, wh ich included abundant immigrant pest source as the foundation of the outbreak, t he variation of biotypes of brown planthoppers, rich food conditions, the increa sing planting area of singleharvest rice which provided good food and habitat  conditions for brown planthoppers, and resistance of brown planthoppers to imida cloprid. It was also suggested to strengthen monitoring in different sites, moni toring insectiside resistance and field investigation.