Comparative Study of Migration Trajectories of the Brown Planthopper, Nilaparvata lugens (Stål), in China Based on Two Trajectory Models

Exotic prediction is an important content for predicting the occurrence of migratory pests. The simulations and prediction of the migration trajectory of pests is considered an ideal exotic prediction method that can reflect the spatiotemporal dynamics of the pest' s migration. The brown planthopper( BPH),Nilaparvata lugens( St?l),is an importantmigratory pest that affects rice production in China and the accurate forecasting of its migration trajectory can provide a scientific basis for the early warnings and effective prevention of pest-related catastrophes. In order to select appropriate pest migration trajectory models with good accuracy,high resolution,and easy popularization,we screened a great northward migration event of BPH that occurred in Hongjiang City of Hunan Province at the beginning of July in 2006,as a typical case of BPH migration in China. The Weather Research and Forecast( WRF) Model,a popular mesoscale weather research and forecast model used both at home and abroad,was used to simulate and output the atmospheric background fields in high resolution combined with re-analyzed meteorological data from the National Center of Environment Predicting of the USA( NCEP). The forecasting variable fields output by the WRF model as meteorological inputs to drive the two trajectory models were coupled with the Hybrid Single Particle Lagrangian Integrated Trajectory( HYSPLIT) Model and the Flexible Particle( FLEXPART) Dispersion Model to predict the migration trajectories and landfalling areas of BPH populations.According to the backward calculation results,the differences between some trajectory parameters of the two models,such as the pest sources,migration paths,migration heights,migrating speeds and migration distance,were compared. Finally,the observed data for the habitat,feeding conditions,and three-dimensional atmospheric airflow fields of BPH' s migration were used to verify the accuracy and precision of the simulations and calculations. The results suggest several important points. First,the two models show good consistent performance on the calculations of pest sources,migration paths( migration azimuth and flight direction),migration heights,migrating speeds and migration distance. However,the variations in the migration parameters in the FLEXPART model are larger than those in the WRF-HYSPLIT model. Second,as compared to HYSPLIT,the FLEXPART model can better represent the dynamical role of meso-scale weather especially convective proce