Foreign Cargo Statistical Data

International trade comprised 12 percent of the country’s freight tonnage in 1998, and that percentage is expected to double by 2020 (USDOT-FHA 2002). Many nonnative species are transported to the United States in import cargo shipments. A fairly conservative projection suggests that international trade will result in the establishment of 120 nonnative insects and plant pathogens in the United States between 2000 and 2020 (Levine and D’Antonio 2003). For forest insects, the largest introduction risk seems to be associated with solid wood packing materials (Haack 2003, Haack 2006). Some of these materials may sit unattended in distribution facilities near ports of entry for weeks or more (Campbell 2001). Several nonnative insects now detected in parts of the United States have been regularly associated with solid wood packing materials, including the Mediterranean pine engraver (Orthotomicus erosus) and the sirex woodwasp (Sirex noctilio) (Haack 2006, Hoebeke and others 2005, Lee and others 2005). Notably, the level of risk associated with wood packing materials may shift with the increased adoption of international regulations and treatment standards. Joint risk assessments by APHIS and the Forest Service suggest that the importation of unmanufactured wood, especially in raw log form, is a high-risk pathway of introduction for a diverse range of insects and diseases (Tkacz 2002). The commercial trade of nursery stock and plant materials is another likely pathway of introduction; evidence suggests that the sudden oak death pathogen (Phytophthora ramorum) was likely introduced via the commercial plant trade (Ivors and others 2006).

The Port Interception Network (PIN) database, maintained by APHIS since 1984, provides information on plant pests intercepted at U.S. ports of entry (Work and others 2005). A number of analyses have made use of the PIN database, along with other data sources such as the APHIS Agricultural Quarantine Inspection Monitoring (AQIM) protocol, to analyze trends in the places of origin and commodities most likely to carry nonnative pests, primarily insects (Brockerhoff and others 2006a, Haack 2003, Haack 2006, McCullough and others 2006, Work and others 2005). Although informative, such analyses are constrained by the fact that only 2 percent of cargo is inspected (NRC 2002), and, thus, many pest introductions may go undetected. As an alternative, publicly available statistical data on international trade offer a means to rank the nation’s ports of entry according to forest pest risk. In particular, filtering such data for countries or commodity types of interest or both may reveal ports where the likelihood of intercepting a specific pest is greatest. In addition, certain data sets provide information on eventual inland destinations, facilitating simple but nationwide risk analyses.

A number of government agencies keep databases on some segment of foreign imports to the United States. The associated data are used to generate national reports on current import patterns, as well as changes in those patterns through time. The databases are similar in format; typically, each database record contains fields listing a particular port of entry, a country or region of origin, an import tonnage, and (sometimes) the commodity type. Records can usually be queried and summarized through time to determine the amounts of high-risk cargo arriving from high-risk locations of origin at individual United States ports of entry. Readily available coordinate information for these ports can be used to develop maps depicting relative risk of introduction for forest pest(s) of interest.