东北迁飞场对粘虫的Pied piper效应

Pied piper effect of the migration arena in northeastern China on Mythimna separata(Walker)

【目的】我国2代粘虫的回迁过程和3代粘虫的种群构成还少有研究,东北与华北3代粘虫的虫源问题也不清楚。为此,需厘清2代粘虫发生区的风场动态和迁出种群的去向,明确东北粘虫夏季迁出种群与华北3代粘虫的虫源关系。【方法】根据国家气象信息中心的高空气象记录,统计东北和华北地区夏季各方位风向的频次和平均出现频率,利用HYSPLIT平台模拟东北粘虫夏季迁出种群的迁飞轨迹和落点分布。【结果】东北和华北地区7、8月的风向均以西南、南风为主且因气旋频繁过境而风向多变,不利于东北粘虫夏季种群回迁进入华北农作区;而对其迁出种群的轨迹模拟结果也表明,东北粘虫夏季种群能够进入华北的可能性极低:它们或迁入更北的无法生存的山区,或未能成功跨海而死亡,抑或迁入朝鲜半岛成为当地的虫源(同样无法越冬),还有一部分滞留东北地区继续为害一代后因气候原因死亡,而只有在极少数风向风速条件适宜的情况下才有可能进入河北。【结论】东北地区的夏季风场不利于东北粘虫的回迁,华北3代粘虫的种群构成与东北夏季种群几无关系,东北迁飞场表现出显著的Pied piper效应。

Objectives Little is known about the return migration process of the 2nd generation and source populations of the 3rd generation of armyworm, Mythimna separata, in northern and northeastern China. To understand the source-sink relationships between inter-regional armyworm populations, it is necessary to identify the synoptic wind fields and clarify the immigration areas of the summer exodus population in northeastern China. [Methods] The frequency of summer winds in eight directions from 1981 to 2000 were calculated with radiosonde data provided by National Meteorological Service Center of China, and the distribution of the end points of migration trajectories of the emigrant armyworm populations was analyzed with NOAA HYSPLIT. [Results] The wind directions in northern and northeastern China in July and August were basically southwesterly and southerly, making it practically impossible for the summer population of armyworms to emigrate into cropping areas in northern China. Meanwhile, the passage of immigrants was restricted to either northeastern China, unsuitable mountainous areas, or the ocean, by the constantly changeable winds and the frequently passage of cyclones. [Conclusion] The summer synoptic wind fields in northeastern China are unfavorable to the southward migration of the local summer armyworm population. Basically, the 3rd generation armyworm population in northern China is unrelated to the summer＆amp;nbsp;population in northeastern China. The migration arena in northeastern China shows a notable pied piper effect on armyworm populations and other insect immigrants.