Migration extent and potential economic impact of the fall armyworm in Europe.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith, 1979), is a major agricultural pest native to the Americas that feeds on several crops, particularly maize. Since 2016, FAW has invaded more than 50 African countries, much of Southeast Asia, and Oceania, severely impacting agriculture and posing a threat to global food security. Following its recent detections in Europe in 2023, this study investigates FAW's migratory capacity and potential direct economic impact on European grain maize production under a "no-control" scenario-areas previously unexplored in the context of Europe. We explored FAW's potential distribution across the European continent by incorporating updated climatic data, refined parameter values, and an expanded occurrence dataset into a revised CLIMEX niche model. Our results reveal sizable potential economic impacts with the southern European Member States facing up to €546 ha grain maize gross margin annual losses, exceeding €900 million under the worst-case scenario. These member states bear the highest risk since they include areas projected to be climatically suitable for both permanent FAW establishment and transient populations during warmer months. This study provides important insights into the risks posed by FAW to Europe and can inform preparedness and decision-making to mitigate the economic consequences of its invasion.