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Predicting Invasions of Nonindigenous Plants and Plant Pests
Network (PIN) database has been maintained by APHIS since 1985. Information in as many as 37 categories is collected when an APHIS inspector finds a pest with potential quarantine significance.
Roughly 53,000 such interceptions are made each year in arriving cargo or baggage. Arthropods, primarily insects, make up 60 to 65% of the records, plant pathogens 25%, plants that are deemed weeds 5%, and snails and other taxa comprise the remainder.
There are recognized limitations in the quality of PIN data. Sampling protocols are not implemented on a consistent and statistically designed basis, and this makes comparisons of interception data between years or locations less reliable. The data underestimate the number of insects or other pests arriving because only one record (for each species) is submitted per interception event, regardless of the number of organisms of a species that are detected in the intercepted shipment. In addition, only organisms determined by APHIS to be “reportable” or “actionable” are recorded. Species that are already widespread or insects that do not threaten plants (such as parasitoids and fungivores) are not included in the PIN database. Limited resources also prevent APHIS personnel from recording negative results; for example, inspections that produce no reportable pests are not recorded. Determining the origin of pests intercepted on cargo is generally straightforward, but identifying the origin of pests intercepted in baggage is often problematic. For example, if fruit flies are intercepted on a mango confiscated from a tourist arriving from France, the only known origin of the fruit flies is France, but the source of the mango and its associated pests was presumably a tropical country. Survey and detection resources and systematic expertise can vary among ports. APHIS entomologists are usually present at ports of entry, but smaller ports might lack plant pathologists or botanists on site. Moreover, techniques to assay for pathogens are unavailable or underused. Organisms of concern (or digital photos) can, of course, be forwarded to specialists for identification, but the process might require that travelers or cargo be detained until the identification is made.
Despite their limitations, the PIN data can be used to develop profiles of pest interceptions at a given point of entry, identify training needs for inspectors, and help regulatory officials to anticipate the arrival of pests that are more likely to be associated with specific imported commodities. More generally, PIN data can be used to assess patterns in the arrival of nonindigenous insects and reveal how the patterns may change in time or vary among ports.
For example, Haack and Cavey (1997) used PIN data to assess nonindigenous insects arriving in the United States on wood packing and crating material. In 1985-1996, 5885 insects originating in 87 countries were intercepted in wood material at U.S. ports. Although 10 orders and at least 54 insect families were intercepted during the 12-year period, almost 95% of the insects were beetles (order Coleoptera). Nearly all the insects were bark beetles or wood borers. Those insects present a clear concern in detection and eradication because much