Occurrence Dynamics Of Fall Armyworm In China In 2019 And Analysis Of Cases In Henan

The fall armyworm,Spodoptera frugiperda(J.E.Smith)is a major migratory pest that invaded China in early 2019.It has now completed its invasion and colonization process in China,and has formed annual breeding area in southern China.As of the end of 2020,hazards have been found in 28 provinces(cities,autonomous regions)in China,causing huge economic losses to crops.Therefore,it is urgent to clarify its occurrence rules and insect source distribution in China in order to provide a reasonable basis for China’s monitoring,early warning and scientific prevention and control.Based on the actual occurrence of fall armyworm in China in 2019,combined with historical meteorological data,using the threedimensional trajectory analysis of insects and the effective accumulated temperature model,the occurrence of fall armyworm in China in 2019 was studied.The moth was studied as an example to clarify the occurrence and distribution of insect source of fall armyworm in China.The main findings are as follows:1.Migration peak period and source distribution of fall armyworm in China in 2019According to the data analysis of the first discovery of fall armyworm in each province of China in 2019,combined with meteorological data,using the trajectory analysis method and the effective accumulated temperature model,analyze the occurrence of fall armyworm in China.According to the results,there are three main migration peaks of fall armyworm in China in 2019:(1)In early May 2019,the adults mainly migrated to Jiangxi,Zhejiang,and Hunan from Laos,Myanmar,Thailand,Yunnan,and Guangxi,Hubei and southern Anhui,Guizhou,southern Chongqing,and eastern Sichuan;(2)In early June 2019,adults mainly from Guangdong,Hunan,Hubei,Jiangxi,Zhejiang,Guizhou,Chongqing and Sichuan provinces migrated to Jiangsu,Anhui,and Hubei North and southern Henan,northern Sichuan and southern Shaanxi;(3)In early August 2019,mainly adults from Jiangsu,Anhui,Henan,Gansu and Shaanxi provinces migrated to Shandong,northern Henan and southern Hebei,Gansu,Ningxia and southwestern Shanxi.The annual peak period of fall armyworm appears to occur from the south to the north,and each migration peak harms 5 latitudes.2.Analysis on the occurrence of fall armyworm in HenanHenan province is located in the mixed migration zone of fall armyworm on the east and west lines of China.It is also the key prevention zone in the north of China “Three Zones and Three Beltes” of fall armyworm and the Huanghuaihai interception zone.It is also one of the main corn producing areas in China.In order to clarify the law of occurrence of fall armyworm in Henan province,based on the insect situation data and meteorological data of the past two years,the method of trajectory analysis and effective accumulated temperature model was used for analysis.The results showed that from May to August in Henan province,the fall armyworm mainly migrated from Hunan and Hubei provinces.Among them,in early April-May,Guangxi,and August,Jiangsu,Anhui,and Shaanxi also had adult migration damage;There are two migration routes,east and west.The east line starts from Xinyang and gradually migrates to the north to spread the hazards,and the west line starts from Nanyang to the north,and the province as a whole shows a trend of hazards from south to north and east to west;The annual occurrence of 3-5 generations in the cities south of the Yellow River in the province,the 1-2 generations in the north of the Yellow River,the severe damage in the cities in the southeast,and the large number of generations;the reason for the difference of one month between the first appearance and the peak migration period of Henan fall armyworm in 2019 and 2020 is mainly due to the continuous large-scale precipitation in the south from June to July in 2020.