Seasonal migratory patterns of Cnaphalocrocis medinalis in the region of Southwest China and Myanmar.

Background: The rice leaf folder (RLF), Cnaphalocrocis medinalis, is a major migratory pest in rice-producing areas of Asia. Previous studies on RLF seasonal migration patterns have primarily focused on the eastern region of the Indochina Peninsula and East Asia; however, its migration in Southwest China and Myanmar remains largely unknown. RLF movements were monitored between 2019 and 2024 in Ruili City of Yunnan Province, China, a border site of insect migratory corridor between Southwest China and Myanmar.

Results: RLF migratory activity in this region primarily occurred between June and November and was divided into three stages. Period I (June to mid-July) was characterised by smaller populations, comprising individuals originating from central and eastern Myanmar, and some immigrants from Thailand, Laos and Vietnam. Period II (late July to August) had the largest migratory population. Almost all RLF that migrated to Ruili City originated from Myanmar, with some migrants continuing to spread throughout western and central Yunnan after passing through the site. Period III (September to November) featured a reduced population in the late migratory season, primarily comprising local RLF in Ruili and a few populations from central Myanmar that extended into Southwest China.

Conclusion: Our findings clarify the unidirectional migration pattern of the RLF in the region of Southwest China and Myanmar, providing a theoretical basis for developing regional management strategies against this pest. © 2025 Society of Chemical Industry.