Risk Factors for Invasive Pest Introductions in Commodity Imports: Theory and Empirical Evidence

Expanded world trade carries with it increased risks of invasions of exotic species and thus increased risks of ecological and economic damage. In the face of such risks, expansion of trade depends critically on the ability to detect unintended introductions of organisms in import shipments and determine whether those introductions are safe as is, safe after appropriate treatment, or unsafe even after treatment. This paper investigates factors associated with greater incremental risk of invasive pest introductions. It develops a conceptual framework based on the production-theoretic notion that invasive pests, like other forms of pollution, can be viewed as an input (or joint output) that serves to lower the cost of producing a commodity. In equilibrium, the prevalence of invasive pests in import shipments depends on production conditions and technology in the exporting country, commodity value and volume, and tariff rates. This conceptual framework suggests that the equilibrium rate at which invasive pests are present in import shipments will vary by commodity, country of origin, value, volume, and season as well as by regulatory factors such as whether pests that may be present in shipments of a commodity are treatable. These results are used to specify an econometric model of factors associated with heightened risk of invasive pest introductions. The parameters of the model are estimated using data from surveillance screening of fruit and vegetable imports into the US during fiscal years 2005-2007. The estimated parameters of the model are consistent with the predictions of the theoretical model. We use them to identify commodities and regions of origin of significantly high and low risk of invasive species introductions