Where do they go, and from where do they come? Advancing pest forecasting through integrative stable isotope techniques and pest origin mapping

Understanding the spatial and temporal dynamics of lepidopteran pest movement is critical for improving IPM/IRM. Traditional tools, such as radar, mark-recapture, trapping, and genetic markers, have significantly advanced our understanding of insect movement. However, resolving the origin and migratory routes of insects across broad geographic scales remains challenging. This research integrates stable hydrogen isotope analysis with long-term pheromone trapping and environmental data to trace the natal origin and movement patterns of key migratory pests, including Helicoverpa zea and Spodoptera frugiperda. This approach provides some of the first evidence for bidirectional migration in both species. In H. zea, results revealed northward dispersal from the southeastern U.S. and, remarkably, southward migration from Northern areas in the U.S. to Florida and the Caribbean. For S. frugiperda, isotopic data integrated with long-term data collection and weather conditions showed that some individuals in Florida originated from the northern Corn Belt, supporting the reverse (southward) migration. Additionally, this integrative isotopic approach demonstrated that tropical cyclones (e.g., hurricanes) can significantly alter S. frugiperda moth dispersal and abundance in a convergence zone (northwest Florida) between the overwintering populations from south Florida and south Texas, further emphasizing the role of extreme weather in pest ecology and IPM/IRM. By combining biogeochemical markers with ecological monitoring and climate data, this integrative framework can enhance early-warning systems, inform resistance management, and support spatially targeted control efforts. This method represents a significant advance in applied entomology, offering a globally relevant tool for predicting pest pressure and mitigating resistance spread in agricultural landscapes.