High risk of the Fall Armyworm invading into Japan and the Korean Peninsula via overseas migration
The fall armyworm, Spodoptera frugiperda (J.E. Smith) is an emerging and most severe pest species in the Old World. It is originally native in the Americas. Since 2016 it has spread widely and rapidly to throughout Africa, the Middle East, India, Southeast Asia and most recently southern China. By May 2019 it has appeared in 13 provinces in most southern China and would spread further to northern China. It is highly likely that S. frugiperda would enter into Japan and Korea via overseas migrations as many other migratory pests did before. To evaluate the invasion risk of S. frugiperda into Japan and Korean Peninsula, we modelled the rate of expansion and future potential migratory range of the insect by a trajectory analytical approach with flight behaviour of S. frugiperda implemented, and meteorological data of past five years (2014-2018) used. Our results predicted that S. frugiperda would migrate from southern and eastern China into Japan and Korea soon. Most likely, Japan would be invaded from Fujian and Zhejiang on 1 June - 15 July, and Kyushu, Shikoku and south-western Honshu could face the highest risk of S. frugiperdas invasion. Korea would be most possibly reached by S. frugiperda from northern Zhejiang, Jiangsu, Anhui, and Shandong on 1 June - 15 July and later. Our results indicated a very high risk that S. frugiperda would annually invade Japan and the Korean Peninsula and cause a possible significant decrease in agricultural productivity.