Original area of fall armyworm individuals newly invaded in Zhejiang Province.
Objective: The fall armyworm, [Spodoptera frugiperda (J. E. Smith), FAW] is a significant migratory pest newly invaded China. It was discovered in Jiande City of Zhejiang Province on 8 May 2019, and thereafter spreaded rapidly throughout Zhejiang Province. A better understanding of the distribution of the source areas and the migration path of FAW populations will be beneficial for the monitoring, early warning and the source control of this pest in Zhejiang Province. Methods: The migratory routes and weather fields for the newly invasive population in Zhejiang Province were analyzed by using a trajectory simulation approach, combined with flight behaviour and meteorological data. Result: According to the larval developmental period, the first batch of FAW adults may immigrate into Zhejiang Province from 26 to 30 April. In late April, the southwesterly airflow passed through most part of southern and eastern China, providing a carrier airflow for the FAW migrants, while low temperature barriers, rainfall and sinking airflow can cause a forced landing of the FAW. The effective source of the FAW invasive population in Jiande City, Zhejiang Province is mainly distributed in eastern Guangxi. Conclusion: This research results lay a basis for the monitoring, early warning, scientific prevention and control of the spring immigrants of FAW in Zhejiang Province.