Abstract: Understanding the impacts of the atmospheric oscillation with quasi-biweekly low frequency on the immigration of brown planthopper (BPH), Nilaparvata lugens (St?l) could provide an important reference to the extended-period forecast of its occurrence. The daily BPH’s light trap data from 105 plant protection stations in China, the daily reanalyzed meteorological data from the National Center of Environment Prediction (NCEP), and the data from the National Center of Atmospheric Research (NCAR) from 1979 to 2015 were collected. It took 2010 as a typical year with occurrence characteristic of BPH, and the relationship between the amount of BPH migrated in rice-growing region from Nanling Mountain to the Yangtze River and the atmospheric oscillation with quasi-biweekly low frequency was analyzed. HYSPLIT (hybrid single particle Lagrangian integrated trajectory) model was used to analyze the backward trajectory of the brown planthopper population at the typical site. The impacts of the atmospheric oscillation on insect sources and migratory paths of BPH was discussed. The results showed that, （1）10-20d oscillation cycle of BPH amount existed significantly in the rice-growing region from the Nanling Mountain to the Yangtze River during August and September in 2010. （2）Wind fields, geo-potential height fields and vertical velocity fields on the isobaric surfaces of 850hPa and 925hPa appeared significant low-frequency cycles of 10-20d simultaneously. And the low-frequency oscillation of BPH’s immigrating amount was correlated significantly with these atmospheric physical variables. （3）Under the impacts of the low-frequency southwestern wind, the populations of BPH were transported from the rice-growing region of southwestern China to the rice-growing region, from the Nanling Mountain to the Yangtze River. In the later period, the part of BPH’s populations immigrated from the rice-growing region between the Huaihe River and the Yangtze River to the rice-growing region between the Nanling Mountain and the Yangtze River under the impacts of the low-frequency northeastern wind.（4）Results of backward trajectory analysis of Brown Planthopper Population was provided to confirm that the insect sources and migration paths of BPH’s populations that immigrated into the rice-growing region between the Nanling Mountain and the Yangtze River were consistent with the low frequency prevailing wind fields.

Key words: Nilaparvata lugens (St?l), Wavelet analysis, Low-frequency atmospheric airflow field, Migration trajectory, Region of insect source