Early warning method for migratory populations of Spodoptera exigua based on biological attractants in southwestern China

As migratory pests endanger global food security, small-scale farming urgently needs simple, efficient early-warning methods against regional outbreaks. 2021–2024, we monitored Spodoptera exigua using food and sex attractants in Yunnan Province. Four-years monitoring revealed that S. exigua exhibited 2–3 peak periods in both spring/summer and autumn. Each peak comprised > 90% adults aged over 3 days and < 10% adults aged 1–2 days, indicating that these populations were predominantly migrants. Trajectory analysis revealed that these migrants traveled primarily northward from southwestern Yunnan (bordering Myanmar) and southern Yunnan (adjacent to Laos and Vietnam), with some reverse (southward) trajectories also observed. We also determined the life-history traits of these migrants’ offspring using life table analysis. Based on these results, an early warning method for immigrant S. exigua was established; it demonstrated a positive correlation between predicted and actual field larval abundance, providing crucial technical support for regional pest management.