Mapping the global threat of Mythimna separata (Walker) and its economic implications for Brazil's agriculture

BACKGROUND: Identifying high-risk areas for the introduction of invasive alien species is particularly important for agricultural pests with a broad host range that attack widely cultivated crops, such as the oriental armyworm, Mythimna separata (Walker, 1865) (Lepidoptera: Noctuidae). This study aimed to assess the global climatic suitability for M. separata and evaluate the economic risk for maize, rice, sorghum, sugarcane, and wheat cultivation in Brazil in the event of invasion and spread to suitable areas. Climatic suitability was estimated using the maximum entropy (MaxEnt) algorithm, and the Normalized Concentration Index (nCI) was calculated to assess the concentration of crop production across Brazilian municipalities. RESULTS: The selected model showed strong discriminatory power, with Area Under the Curve and Continuous Boyce Index values above 0.85. Moderately to highly suitable areas were identified beyond the species' native range, including North, Central and South America, Europe, southeastern Australia, and New Zealand. Globally, 35.0%, 39.0%, and 46.9% of areas cultivated with rice, maize, and wheat, respectively, fall within regions classified as moderately to highly suitable. In Brazil, estimated economic risk varied substantially among crops, with wheat showing the greatest vulnerability. CONCLUSION: Integrating regional crop production data with invasion risk maps proved useful in identifying priority areas for preventive actions, supporting the targeting of surveillance and management efforts to mitigate potential economic losses.