Early-Warning Assessment of Two-Spot Cotton Leafhopper (Amrasca biguttula) Using the Normalized Research Risk Metric (NRRM) Across Multiple Invasive Species

The two-spot cotton leafhopper (Amrasca biguttula) is an emerging invasive pest in the southeastern United States, with recent establishment in cotton, vegetables, and ornamental hibiscus. Its rapid spread, potential economic losses, and regulatory impacts highlight the need for additional early-warning tools capable of identifying high-risk arthropod invaders before widespread establishment. We developed and applied the Normalized Research Risk Metric (NRRM), a literature-based framework that quantifies global research visibility using total publications, recent research, research momentum, and geographical breadth. A comprehensive multi-database Web of Science search was conducted across all available indices using species-specific synonyms, address filters, and harmonized country names. Six globally important invasive species were used to train the model, and A. biguttula was evaluated as the primary prediction species. The species exhibited high global research visibility (T = 403; C = 25) and a positive NRRM score (0.651), consistent with its long-recognized pest status in Asia and its rapid emergence in the U.S. In contrast, Heliococcus summervillei received a strongly negative NRRM score (−1.14). NRRM provides a rigorous early-warning indicator that can be integrated with ecological and eco-climatic models to further improve the prediction of future invasive threats in agricultural and horticultural systems.