武陵山区白背飞虱大发生种群的形成:2007年个例分析

The formation of outbreak populations of Sogatella furcifera(Horváth) in the Wuling Mountain area:A case study in 2007

【目的】武陵山区白背飞虱Sogatella furcifera(Horváth)的频繁暴发,给当地的水稻生产造成了极其严重的损失,明确其大发生的机制,对于实现精细化异地预测和综合治理至关重要。【方法】用WRF模拟风温场,用HYSPLIT模拟迁飞轨迹,对武陵山区2007年白背飞虱多个灯诱高峰的虫源分布和降落机制进行不同尺度的模拟分析。【结果】(1)西南低空急流是武陵山区白背飞虱早期种群形成的首要条件,降水、低温屏障、下沉气流和地形阻隔是造成此次洪江早期种群大发生的主要原因。(2)2007年主害期,我国南方的大面积高温干旱天气刺激了白背飞虱的大量外迁,为武陵山区提供了更加充足的虫源;连续多日的降水致使迁入种群大量聚集降落,同时也使得本地外迁种群迁出受阻,从而造成了武陵山区白背飞虱种群的大发生。(3)地形引起的垂直涡旋等小气候变化是造成不同站点间迁入虫量差异的主要原因。【结论】西太平洋副热带高压所带来的西南暖湿气流与北方冷涡南下的冷气团常在武陵山区上空交汇,形成大范围长时间的强对流天气,加之该地区西南低涡的强辐合作用,从而造成了2007年武陵山区白背飞虱种群的大发生。

[Objectives] Successive outbreaks of the white-backed planthopper, Sogatella furcifera （Horvath） （WBPH） in the Wuling Mountains have seriously damaged rice production. Better understanding of the outbreak mechanisms of this species is important to improving the accuracy of outbreak forecasting and the integrated management of this pest. [Methods] Wind and temperature fields were simulated by the mid-scale atmospheric models WRF and GrADS. The trajectories of immigrant WBPH were tracked by the NOAA atmospheric dispersion model, HYSPLIT. Source areas and landing mechanisms of immigrant WBPH in the Wuling Mountains in 2007 were studied by trajectory analysis and synoptic analysis. [Results] （1） Southwest low level jet streams were the primary conditions for the early formation of outbreak populations of WBPH in the Wuling Mountains. Precipitation, downdrafts, geographical obstacles such as mountain ranges, and low temperatures are barrier factors that impede early immigration events. （2） The main outbreak period coincides with prolonged periods of high temperature and dry weather in southern China which stimulate massive numbers of WBPH to migrate. Immigrant populations of WBPH are much more abundant than before in the Wuling Mountains. Prolonged precipitation over several days is thought to be the main factor causing large numbers of WBPH to land and preventing the migration of local populations. （3） Vertical＆amp;nbsp;vortices and other microclimatic factors caused by topography are the reason for site-specific differences in migration. [Conclusion] A southwest, warm, moist air flow generated by subtropical high pressure systems over the Western Pacific frequently meets the cold air flow generated by the cold vortex over Northeast China in the Wuling Mountains causing long-term and large-scale convection. In addition, convergence of the southwest vortex caused outbreaks of WBPH in the Wuling Mountains in 2007.