2021年西北地区二代黏虫重发区的虫源分析

Source in serious outbreak areas of the second generation of Mythimna separata in Northwest China in 2021

明确一代黏虫Mythimna separata(Walker)的迁入路径和各发生区域间的虫源关系,对二代幼虫的有效防控具有重要意义。本研究选取西北地区黏虫重发的典型年份2021年,收集多地黏虫时空种群动态数据,采用FNL再分析数据资料绘制风场图,利用基于WRF模式的轨迹模型对迁飞轨迹进行模拟,并使用R 4.0.2进行轨迹的可视化。虫情监测表明,2021年一代黏虫迁飞高峰期主要集中在6月上中旬,中西部地区高峰期呈多峰现象,蛾峰日期随纬度升高依次推迟。风场分析显示,一代黏虫北迁期间,华北、东北和西北地区受东北气旋、蒙古气旋和东亚气旋交替控制,适于黏虫远距离迁飞的偏南气流间歇性出现,但很难实现一次性远距离迁飞,锋面天气阻碍了黏虫的北迁,并造成聚集降落。轨迹分析结果表明,黄淮、江淮地区一代黏虫羽化后,部分滞留当地,大部分迁入华北、东北和西北地区,东西部地区存在虫源交流;宁夏、陕西、内蒙古等西北地区重发生区虫源主要来自山西、陕西、甘肃南部和四川、重庆北部等地。本文研究结果可为黏虫的监测和防控提供新思路。

The identification of migration paths of the first generation of Mythimna separata and the source relationships between different occurrence areas are crucial for the effective control of the second generation of M.separata larvae.In this study,we collected spatiotemporal dynamics data of M.separata populations from multiple regions in Northwest China during 2021,a typical year with a high incidence of M.separata.We used FNL data to draw wind field maps,simulated migration trajectories using a trajectory model based on the WRF model,and visualized the trajectories using R 4.0.2.Insect monitoring results showed that the peak period of the first generation of M.separata’s migration in 2021 was mainly concentrated in early to mid June,with a multi-peak phenomenon in the peak period observed in western China.The peak date of the moths was postponed with the increase of latitude.Wind field analysis showed that during the northward migration of the first generation of M.separata,the Northeast cyclone,Mongolia cyclone,and East Asian cyclone alternately influenced the regions of North China,Northeast China,and Northwest China.The southerly airflow suitable for long-distance migration of M.separata appeared intermittently.One-time long-distance migration was challenging due to frontal weather hindering the northward migration of M.separata,causing them to gather and land.The trajectory analysis showed that after emergence of the first generation of M.separata in the Huanghuai and Jianghuai regions,some remained in the local area,while the majority migrated to North,Northeast,and Northwest China.Insect source exchange occurred between the eastern and western regions.The main sources of M.separata in severe outbreak areas in Northwest China,such as Ningxia,Shaanxi,and Inner Mongolia,originated from Shanxi,Shaanxi,southern Gansu,northern Sichuan and Chongqing.The results of this study can provide new insights for monitoring and controlling M.separata in the new era.