Pied Piper Effect Of The Insect Migration Arena In Northeastern China

The average frequency of winds from eight directions and average temperature of each station in Northeastern China were counted by the standard wind and temperature data (85OhPa 1980-1995, surface 195J~?980) from Chinese Meteorological Bureau The results indicated that although the air temperature of surface between June and September and aero-temperature on the 85OhPa standard isobaric surface between June and August were suitable for the southward return migration of many insects during the late summer and early autumn, but the dominant winds were SW, 5, W and NW, which were disadvantage for the return migration of many immigrants to Southern China. And the NE and Northerly which transport the insects southwards were few and with lower speed. Meanwhile the analysis of the correlation between the wind frequency of 8 different direction and the damage of the second generation of armyworrn (Mythimna separata) in Northeastern China showed that the outbreak scales of the second generation armyworm in Jilin province were negative correlated to SW at 20:00 (Beijing Time) and no relation to the other wind directions, while it was correlated to S and SE but negative correlated to SW in Liaoning province. So it was nearly impossible for armyworm to return to Southern China during this period. There were indications that the characteristics of physical geography in Northeastern China caused strong pied piper effects to arrnyworm and other spring immigrants to this area. To expound the mechanism of summer outbreaks of armyworm, the II emigration trajectories of the second generation armyworm in Northeastern China in special years (1978, 1980, 1981, 1982) were simulated and analyzed. The case studies indicated that the emigration trajectories were varying dramatically from date to date and from place to place. Their fate was mostly falling into the Sea of Japan, Yellow Sea, Bohai Sea, Daxinganhing Mountain, Xiaoxinganling Mountain and so on, where were severe environment for their survive. But some moths did be detained to the localities in northeastern China when they were caught by the oscillation of summer monsoon or by the circuitous wind systems (e.g. frequent passage of the Northeastern cyclone and Mongolia cyclone), that made their pathways moving to and fro or circularly and the emigrant population could not leave Northeastern China successfully. It was the detained moths that constituted the outbreak populations and the wind circulation caused the pied piper effect in Northeastern China.