Trajectory Analysis Of Immigration Population Of Meadow Moth In Northeast Part Of China

Meadow moth Loxostege sticticaiis L. (Lepidoptera: Pyralidae), also called sugar beet web-worm, etc. is a worldwide pest, distributed in Europe, Asia and North America. In our country, it mainly distributes in northern and northeast parts of China, and is an important migratory pest on the crops in northern parts of China, meadow moth has a character of periodical outbreaks. Since 1997, the harm from meadow moth has become more and more serious and reaches to a historic peak in 1999. But now, people are still lack of a whole recognition to its exact over winter area and migratory path. The mechanism of meadow moth' s outbreaks in northeast part of China needs to be studied thoroughly.In order to expound the mechanism of meadow moth, in this paper, a trajectory analyzing model is built with diagnosis method, using the wind data on 600m of 24 stations and history weather map published by Chinese Meteorological Bureau. Migration trajectories of meadow moth in special years (1997, 1998, 1999 and 2001) are simulated and analyzed.The research results indicate that weather system has notable effect on the migration of meadow moth. Large scale invasion of meadow moth is coincident with strong quasi-south or southwest air current caused by circuitous wind system (such as cold-vortex and cyclone). So the appearance and enhancement of circuitous wind system could be a pre-warning indicator for the immigration of outbreak populations of meadow moth in northeast of China. Trajectory analysis also indicates that there are only fewer outbreaks of meadow moth in northeast part can be traced back to northern China. With integrated analysis, a conclusion can be made that the population of meadow moth in northern China has little effect on the outbreak in northeast part in most years and the outbreak population in northeast part should come from the over winter area in north. At the same time, trajectory analysis indicates that most trajectories were traced back to the middle and south part of Daxinganling Mountain and border between China and the east part of Mongolia. It is estimated that perhaps it is the main source area for outbreak population of meadow moth in Songnen Plain and there should be large over winter area every year in that region, whether this presumption is true needinvestigation among states.