Rising pest-status of the emerald ash borer in its native range is linked to the introduction and planting of exotic ash species

Biological invasions are among the most serious threats to forest ecosystems worldwide. Understanding invasion processes and the ecology of invasive pests in invaded and native habitats is necessary for effective management. We analyzed historical data on the geographic distribution and spatiotemporal dynamics of emerald ash borer (EAB, Agrilus planipennis) in its native habitats in China. We examined the effect of host tree species planted from 1900 to 2019 on the distribution, occurrence, and frequency of EAB outbreaks in China. Exotic North American and European ash species planted primarily in northern, northeastern, northwestern and central China, were more susceptible to EAB compared with native Asian ash. EAB infestation level was positively correlated with latitudinal distribution of non-Asian ash trees, but not with their habitat, altitude, or diameter at breast height. The frequency and level of EAB infestations gradually increased following introduction and widespread plantings of non-Asian ash trees in the 1900s, and the first recorded outbreak of EAB in China occurred after 30-50 year time lag. Increased EAB populations in China in the 1990s likely enhanced its invasion risk to other regions including North America, as trade activities with China increased and susceptible host plants were abundant during this period.