Analysis of migratory routes and atmospheric features of the newly invaded fall army worm, Spodoptera frugiperda (J. E. Smith) in Guangdong Province.
The fall armyworm, Spodoptera frugiperda (J. E. Smith), is an extremely destructive agricultural pest worldwide, which has been warned by the United Nations' Food and Agriculture Organization (FAO) since 2016. It first invaded the southwestern part of Yunnan Province, China in January 2019, and thereafter immigrated or spread to South China as the southwestern monsoon blows in spring. It is reported for the first time that a great number of larvae of the fall armyworm were present in the corn field in Guangzhou City's Zengcheng district, Guangdong Province on April 23th, 2019. It will pose a serious threat and damage to crop production, especially to maize production in Guangdong Province. The migratory routes and weather fields for the case of the newly invaded fall armyworm in Guangdong Province were simulated by using Weather Research and Forecast (WRF) Model and Grid Analysis and Display System (GrADS), combined with reanalyzed meteorological data from the National Center of Environment Predicting (NCEP) of the USA. The results showed that according to the development period of larvae, the first invaded adult population of the fall armyworm might immigrate to Guangdong Province from April 8th to April 13th, 2019. During this period, southwest of strong low-level jet between northern Vietnam and South China carried migratory populations of the fall armyworm into Guangdong Province. The landing populations of the fall armyworm were caused by wind shear, rainfall and downward flow. The effective migratory of the fall armyworm took place on April 9th and April 10th, 2019. Simulations of migration trajectories indicated that the immigrants of the fall armyworm in Zengcheng district came from Northern Vietnam and Northern Laos. This study provided a scientific basis for monitoring, early warning and control of spring migratory populations of the fall armyworm in South China.