Retrospective analysis of factors affecting the distribution of an invasive wood-boring insect using native range data: the importance of host plants

Climate is a critical factor considered in predicting the potential distributions of species. However, the distribution of susceptible host plants is another important constraint in retrospective and predictive analyses of invasive insect pests, particularly for wood-boring insects. In the present study, we first modeled the geographic distribution of the invasive emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), and its susceptible host trees using MaxEnt. We then compared the differences between the predicted and actual distribution of EAB in its native (China) and invaded (the United States and Canada) ranges by incorporating the distribution of its susceptible host plants. Results from our models indicate that: (1) in addition to climatic factors, the presence of susceptible host tree species plays a major role in delineating the pest's distribution; (2) it is more accurate to project EAB's potential range distribution by considering the suitability of potential areas for its susceptible host plants; and (3) there is a high risk of EAB expanding its current distribution areas in both its native and invasive ranges. The inclusion of susceptible host plant presence as a factor enables more effective predictive modeling and risk assessment for biological invasions, especially for oligophagous insects.