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

Authors: GAO, FAN-QI - University Of Exeter; Meagher Jr, Robert; Nagoshi, Rodney; CHAPMAN, J - University Of Exeter; EARLY, R - University Of Exeter

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2025
Publication Date: 9/18/2025
Citation: Gao, F., Meagher Jr, R.L., Nagoshi, R.N., Chapman, J.W., Early, R. 2025. Predicting the seasonal distribution of fall armyworm in North America using species distribution models. Pest Management Science. https://doi.org/10.1002/ps.70217.
DOI: https://doi.org/10.1002/ps.70217

Interpretive Summary: Species distribution models are widely used in pest management to predict potential outbreak areas of certain pests. Migratory pests cause seasonal damage to crops through long-distance migration, making it crucial to understand their seasonal activity when estimating outbreak regions. Fall armyworm, is a highly migratory pest, which causes damage to corn and other crops in the central and eastern U.S. Collaborators from the University of Exeter in the U.K. along with scientists from USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, developed species distribution models for individual months or combined seasons using fall armyworm sampling data and environmental variables. The results showed that the suitable habitat for fall armyworm expands rapidly in summer, covering most of the central and eastern U.S. in July and August, and then begins to reduce in area in September. Fall armyworm distribution in winter is mainly influenced by minimum temperature, while in spring, corn cultivation area and the amount of vegetation in the landscape also play important roles. In summer, minimum temperature is no longer important, and the main factors are precipitation, evapotranspiration, corn cultivation area, and vegetation area. In autumn, minimum temperature becomes important again, while corn cultivation area is no longer a key factor. This study indicates that fall armyworm may have outbreaks across the central and eastern U.S. in July and August, emphasizing the necessity of scouting corn fields and early pest management strategies.

Technical Abstract: Environmental and species presence data for fall armyworm (FAW), Spodoptera frugiperda, were used to design species distribution models (SDMs) in the central and eastern U.S. Based on model results, the suitable habitat for FAW expands rapidly in summer, covering most of the central and eastern U.S. in July and August, and then begins to contract in September. Based on the environmental variables included in the models for different seasons, FAW distribution in winter is mainly influenced by minimum temperature. In spring, rainfed corn cultivation area and the 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. This study indicates that FAW may have outbreaks across the central and eastern U.S. 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 seasonal distribution could improve prediction accuracy by identifying key environmental variables in each season and refining niche characterization.