Predicting the seasonal distribution of fall armyworm in North America using species distribution models.

BACKGROUND Species distribution models (SDMs) are widely used in pest management to predict outbreak areas. Migratory pests cause seasonal crop damage through long-distance migration, making it crucial to understand their seasonal activity when estimating outbreak regions. Fall armyworm (FAW), a highly migratory pest, was studied using SDMs to predict its seasonal distribution in the central and eastern USA and explore the environmental factors influencing its distribution. RESULTS We used monthly environmental and species distribution data to model each month or season individually. Based on model results, the suitable habitat for FAW expands rapidly in summer, covering most of the central and eastern USA in July and August, and then begins to contract in September. Based on the environmental variables included in models for different seasons, FAW distribution in winter is mainly influenced by minimum temperature. In spring, rainfed corn cultivation area and Normalized Difference Vegetation Index (NDVI) also play important roles. In summer, minimum temperature is no longer important, and the main factors are precipitation, evapotranspiration, rainfed corn cultivation area, and NDVI. In autumn, minimum temperature becomes important again, while rainfed corn cultivation area is no longer a key factor. CONCLUSION This study indicates that FAW may have outbreaks across the central and eastern USA in July and August, emphasizing the necessity of implementing early large-scale pest control. Using separate models for each season, rather than a single model to predict whether seasonal distribution could improve prediction accuracy by identifying key environmental variables in each season and refining niche characterization. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.