Climatic suitability and spread potential of Anoplophora horsfieldii (Coleoptera: Cerambycidae), a newly identified non-native insect on Jeju Island, Korea

In 2022, the non-native longhorn beetle Anoplophora horsfieldii (Hope) was officially reported on Jeju Island, Korea, marking its first confirmed occurrence outside its native range. This insect damages living hackberry trees, a common species in Korea, posing a significant threat to tree health due to its high population levels on Jeju Island. This study aimed to estimate the climatic suitability and spread potential of A. horsfieldii to support its effective management in non-native regions, particularly on Jeju Island. We adopted a species distribution modeling (SDM) approach using global presence records and bioclimatic variables to estimate its climatic requirements. Random forest (RF) and gradient boosting machine (GBM) algorithms were used to construct climatic niche models, and their outputs were combined into an ensemble prediction to identify regions with high climatic suitability. Potential habitats were further delineated by integrating the climatic suitability map with vegetation data from Jeju Island. Using this habitat map, we simulated the potential spread of A. horsfieldii on Jeju Island, incorporating demographic processes and various dispersal parameters. Our findings indicate that A. horsfieldii could potentially spread across parts of Southeast and East Asia, including southern Korea and Japan. On Jeju Island, extensive suitable areas were identified through host distribution analysis, suggesting that A. horsfieldii could establish across the island except in the high-altitude regions of Mt. Halla. The spread potential analysis highlights the urgent need for prompt actions to control the expanding population on Jeju Island and calls for further ecological studies on this potential invader. Despite uncertainties arising from limited ecological information, this study highlights the necessity of implementing domestic quarantine measures and control strategies while considering multiple spread scenarios and the dispersal behavior of this insect.