Economic Impacts of Non-Native Forest Insects in the Continental United States

TLDR

Reliable estimates of the economic impacts of the more than 450 non‑native forest insects established in the United States are lacking, yet such data are essential for credible management, trade, and regulatory policies that protect the ecosystem services and social benefits provided by forests and urban trees. The study aims to develop a novel modeling approach that maximizes available data, accounts for multiple uncertainties, and estimates costs for three major feeding guilds of non‑native forest insects. For each guild, the model calculates economic damages across five cost categories and estimates the probability of future introductions, and its flexibility allows application to other countries or natural resource sectors. The analysis shows that homeowners and municipal governments bear most costs, with wood‑ and phloem‑boring insects expected to cause nearly $1.7 billion in local government expenditures and $830 million in lost residential property values annually, and a 32 % chance of another highly destructive borer invading in the next decade, underscoring the need for cost‑benefit analyses to evaluate policies.

Abstract

Reliable estimates of the impacts and costs of biological invasions are critical to developing credible management, trade and regulatory policies. Worldwide, forests and urban trees provide important ecosystem services as well as economic and social benefits, but are threatened by non-native insects. More than 450 non-native forest insects are established in the United States but estimates of broad-scale economic impacts associated with these species are largely unavailable. We developed a novel modeling approach that maximizes the use of available data, accounts for multiple sources of uncertainty, and provides cost estimates for three major feeding guilds of non-native forest insects. For each guild, we calculated the economic damages for five cost categories and we estimated the probability of future introductions of damaging pests. We found that costs are largely borne by homeowners and municipal governments. Wood- and phloem-boring insects are anticipated to cause the largest economic impacts by annually inducing nearly $1.7 billion in local government expenditures and approximately $830 million in lost residential property values. Given observations of new species, there is a 32% chance that another highly destructive borer species will invade the U.S. in the next 10 years. Our damage estimates provide a crucial but previously missing component of cost-benefit analyses to evaluate policies and management options intended to reduce species introductions. The modeling approach we developed is highly flexible and could be similarly employed to estimate damages in other countries or natural resource sectors.