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

Author of the article:PAN Lei1 WU Xiang-Wen1# CHEN Xiao1 JIANG Yu-Ying2 ZENG Juan2 ZHAI Bao-Ping1

Author's Workplace：1. Department of Entomology, Nanjing Agricultural University, Key Laboratory of Integrated Management of CropDisease and Insect Pests, Ministry of Education, Ministry of Agriculture of China, Nanjing 210095, China;2. National Agricultural Technical Extension and Service Center, Beijing 100125, China

Key Words：return migration of armyworm, synoptic wind field analysis, trajectory analysis, Pied piper effect

Abstract：ittle 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 northeasternChina. 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 northeasternChina. [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 northeasternChinain July and August were basically southwesterly and southerly, making it practically impossible for the summer population of armyworms to emigrate into cropping areas in northernChina. Meanwhile, the passage of immigrants was restricted to either northeasternChina, 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 Chinaare unfavorable to the southward migration of the local summer armyworm population. Basically, the 3rd generation armyworm population in northernChinais unrelated to the summer population in northeasternChina. The migration arena in northeasternChinashows a notable pied piper effect on armyworm populations and other insect immigrants.