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Abstract
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.