Historical Accumulation of Nonindigenous Forest Pests in the Continental United States

Nonindigenous forest insects and pathogens affect a range of ecosystems, industries, and property owners in the United States Evaluating temporal patterns in the accumulation of these nonindigenous forest pests can inform regulatory and policy decisions We compiled a comprehensive species list to assess the accumulation rates of nonindigenous forest insects and pathogens established in the United States More than 450 nonindigenous insects and at least 16 pathogens have colonized forest and urban trees since European settlement Approximately 25 established nonindigenous forest insects per year were detected in the United States between 1860 and 2006 At least 14% of these insects and all 16 pathogens have caused notable damage to trees Although sap feeders and foliage feeders dominated the comprehensive list, phloem- and wood-boring insects and foliage feeders were often more damaging than expected Detections of insects that feed on phloem or wood have increased markedly in recent years