Rice‐growing areas in the northern part of Hainan Province in China are a source area for seasonal migration of the brown planthopper <scp> <i>Nilaparvata lugens</i> </scp> (Stål)

BACKGROUND: The brown planthopper (BPH), Nilaparvata lugens (Stål), is a highly destructive long-distance migratory pest characterized by its sudden occurrence, outbreak potential, and devastating impact that presents a considerable threat to rice production in countries bordering the South China Sea. The northern part of Hainan Province in China is a key region for double-cropping rice production; however, the migratory dynamics and source-sink relationships of BPH populations in this region remain poorly understood. The seasonal BPH migration patterns were monitored during 2017-2023 in Chengmai County of northern Hainan, using high-altitude light-trap sampling, entomological radar surveillance, and complementary techniques. RESULTS: BPH exhibited year-round migratory activity in northern Hainan, with peak migration observed from April to November. Ovarian dissection of light-trapped individuals showed that > 90% exhibited Stage I ovarian development, indicating that local emigrants dominated the population. An X-band rotating-polarization vertical-looking entomological radar further confirmed the takeoff and emigration behaviors. Trajectory analyses of the simulation model demonstrated that migration was oriented mainly toward the Guangdong and Guangxi provinces of China from late April to early August. The immigrant source region expanded from these two provinces to central Vietnam and Laos from mid-August to early October. Subsequently, from mid-October to early November, migration was mainly directed toward south-western Hainan, central Vietnam, and central Laos. CONCLUSION: Our study indicates that northern Hainan functions as a source region for BPH and characterizes its seasonal migration patterns into southern mainland China, Vietnam, and Laos, providing a theoretical foundation for establishing a monitoring, early warning, and control system for this pest in the northern South China Sea region. © 2026 Society of Chemical Industry.