and meaningful. Data collection should be expanded to include vascular plants (in addition to those on the federal noxious weed and seed lists). Increased efforts are also needed to detect and identify pathogens consistently. Improved technology to detect hitchhiking insects and plant pathogens arriving with cargo, baggage, and related commodities could improve the utility of the PIN database (as well as reduce opportunities for new, potentially invasive pests to immigrate). The value of the database would be increased by including additional variables, such as a record of inspections that result in the detection of zero pests, some measure of the abundance of detected pests, and interceptions of nonquarantined pests. The data should be monitored consistently and regularly to identify and correct problems in data entry or maintenance. The PIN database should be accessible for analysis by investigators in universities and other agencies in collaboration with APHIS personnel who are familiar with the database.

There is great potential to learn more from the PIN data that vary in taxonomic status (such as individual species, families, guilds, orders, and class), spatial scale (such as selected ports, regions, or the entire United States) and temporal pattern. The complexity of the data and the background information needed to interpret it accurately require assistance from APHIS staff. APHIS should continue to collaborate in the analysis of the PIN data with scientists outside APHIS who have the relevant expertise and interests while working to make the database more independently accessible.

Recommendation 2. APHIS risk assessments combine a system of predicting an organism’s arrival and establishment with an estimation of the possible consequences. The assessments are based on scientific concepts but contain uncertainties because of gaps in available information. To strengthen the overall prediction of invasive potential, the basis of APHIS risk assessments should be better documented, and assumptions made in each step should be listed and explained, so that independent experts can rationally compare conclusions about the likelihood of arrival, establishment, and impact. The assessment procedure should be transparent, repeatable, peer-reviewed, and updated to capture new information and enhance expert judgment.

Although risk assessments are used by APHIS to manage imports, they constitute the largest body of predictive systems so far attempted, insofar as they and related systems formed by other nations incorporate a set of assumptions about an organism’s ability to arrive, establish, and cause damage. Those assumptions are tested after a decision to import (or not to import) a commodity or a new plant species. The arrival of a pest may or may not indicate a failure of the assessment, but examining the assumptions in light of new information or events requires that the assessments be explicitly stated.

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