Abstract

Biological invasions are among the most serious threats to native forest ecosystems worldwide due to ever-increasing global trade and climate change. Understanding invasion processes and the ecology of invasive pests in both newly invaded and native habitats is necessary to effectively mitigate and manage the risks they pose. The effects of exotic ash tree species planted from 1900 to 2019 on distribution, occurrence, and outbreak frequency of a native pest emerald ash borer, Agrilus planipennis Fairmaire, were examined. The frequency and level of pest infestations gradually increased following introduction and widespread plantings of non-native host trees, and the first recorded outbreak occurred after a time lag of 30-50 years. Increased pest populations enhanced its invasion risk to other regions including the native ranges of introduced plants.