Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), has become an important pest in Chinese agricultural systems since its invasion on 11 December 2018.  After its establishment, FAW months in the year-round breeding region have become the main source population migrating to other areas in China.  Field investigations were conducted in tropical and subtropical regions to improve understanding of its year-round breeding area in China.  The results showed that FAW larval density was significantly correlated with the seasonal temperature of the location surveyed.  The FAW larvae maintained a high density in the tropical area and were frequently found in sites of the south subtropical region, but were absent from the north subtropical region and the northern part of the central subtropical region.  These results indicated that FAW can reproduce annually in the tropical and south subtropical regions of China, including Hainan, Taiwan and the southern area of Fujian, Guangdong, Guangxi, Guizhou, and Yunnan.  Hence, great effort should be made to monitor and control FAW in the year-round breeding region to suppress the population density of this area and to reduce migration of moths into northern parts of China.  This study clarifies the occurrence area of the pest in winter in China and provides much valuable information for its population forecasting and management.

The fall armyworm (FAW, Lepidoptera: Noctuidae), Spodoptera frugiperda (J. E. Smith), invaded China in mid-December 2018; since then, it has become a great threat to Chinese agricultural production.  Qinling Mountains–Huaihe River region (QM–HRR) is the transitional zone between northern and southern China, an important region for both corn and wheat production.  Based on the actual occurrence of QM–HRR invaded by FAW in 2019, daily mean surface air temperature and nocturnal wind conditions at 925 hPa were examined, and migratory routes of FAW moths originated in QM–HRR were modeled by a forward-trajectory-analysis approach.  The results indicated that migratory activities of FAW adults emerged in QM–HRR were initiated from late June.  The moths from western QM–HRR, where has complex topographic terrain, mainly flied to Ningxia and Inner Mongolia before mid September.  However, FAW moths from the eastern QM–HRR primarily engaged in high-altitude northward transport assisted by the prevailing southerly winds before mid August, and the North China Plain was identified as the main destination of FAW.  Meanwhile, the migration trajectories of FAW moths had a possibility to reach the Northeast China Plain.  From mid August, FAW moths in eastern QM–HRR largely migrated southward and returned to the Yangtze River Valley.  This study provides detailed information on the occurrence and migration routes of FAW moths from QM–HRR and will be helpful for early warning and development of integrated pest management strategies for the control of this exotic insect pest.

The fall armyworm (FAW), Spodoptera frugiperda is one of the most damaging crop pests, and it has become major threat to the food security of many countries.  In order to monitor possible invasion of this pest into China, a searchlight trap was established in March 2018 in western Yunnan Province, China, where it has served as the “first station” for many pests that have migrated from Myanmar to China.  A number of suspected FAW moths were captured and identified by DNA sequencing.  The results showed that the FAW moth was first captured on December 11 and formed its first immigration peak in mid-December 2018.  DNA detection revealed that the early invading FAW population was the “corn-strain”.  The field survey indicated that the pest mainly colonized corn in Pu’er, Dehong and Baoshan areas.  Migration trajectory simulation implied that the moths might have mainly come from the eastern area in the mid-latitude region of Myanmar (20–25°N, 94–100°E).  This case study confirmed the first immigration of FAW into China, and will be helpful for guiding monitoring and management work to control this pest.