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United States Department of Agriculture

Agricultural Research Service


item Mccullough, Deborah
item Work, Timothy
item Marshall, David
item Cavey, Joseph
item Liebhold, Andrew

Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2005
Publication Date: 3/1/2005
Citation: Mccullough, D.G., Work, T.T., Marshall, D.S., Cavey, J.F., Liebhold, A.M. 2005. Interceptions of nonindigenous plant pests at u.s. ports of entry and border crossings over a 17 year period. Biological Invasions.

Interpretive Summary: Nonindigenous, invasive plant pests and weeds have dramatically affected the diversity, productivity and function of natural and agricultural ecosystems throughout North America. Successful invasion involves a three step process: the nonindigenous species must arrive in its new habitat, become established, then increase in density and expand its range. Only a fraction of the nonindigenous organisms that arrive become established and invasive. Once a nonindigenous species becomes established, however, management options are typically limited to eradication or regulatory programs to contain or slow the spread of the pest. These efforts are usually costly, may require intensive pesticide applications and are not always unsuccessful. This paper presents an overview and general description of the relative rates and circumstances associated with interceptions of plant-feeding insects, mites, mollusks, nematodes, plant pathogens and weeds at U.S. borders and ports of entry. We summarized PIN (Port Interception Network) data from 1984 to 2000 to examine the origins, interception sites and mode of transport associated with the pests.

Technical Abstract: A total of 728,990 pest interceptions, representing at least 2340 different species, were used in our analysis. Pests were intercepted at 160 points of entry into the U.S. and seven points of entry into U.S. territories. On average, there were 42,882 (SE ± 1,986) pest interceptions recorded annually from 1984 to 2000, ranging from a low of 19,697 in 1984 to a high of 55,522 in 1997. Number of interceptions by month ranged from a total of 54,515 interceptions (7.07% of all records) in December to 73,542 records (9.54% of records) in May. There were 259 different countries recorded as the origin of intercepted pests during the 17-year period. Pre-departure stations in Hawaii and Puerto Rico that clear agricultural products shipped as cargo and produce carried by travelers prior to their arrival in the continental U.S. accounted for 8.5% and 7.7 % of all interceptions, respectively. Insects dominated the PIN database, comprising 77.5% of all records. Plant pathogens, weeds and mollusks made up 13.1%, 6.9% and 1.6% of the interceptions, respectively. Interceptions of mites (0.8%) and nematodes (0.1%) accounted for the remainder of the records. Overall, 87% of pests in the PIN database were intercepted on imported commodities intended for consumption, including 89% of insects, 80% of pathogens, 82% of weeds and 78% of mollusks. This category includes items such as fruit, vegetables and cut flowers. An additional 7% of the records were associated with plant materials intended for propagation such as plant parts (which includes live plants), cuttings, bulbs, seeds and roots. Propagative material, which is examined intensively at plant inspection stations upon entry, was associated with 48% of mite interceptions and 43% of nematode interceptions. Roughly 6% of the pests were intercepted on materials classified as 'non-entry' which refers to items such as dunnage (wood or other material used to support cargo on ships), ship's stores, holds of cargo ships or crew's quarters. This included 6% of all insects, 12% of mites, 14% of pathogens, 14% of weeds, 4% of mollusks and 16% of nematodes. The remaining pests (roughly 1.5%) were collected from mail containers or miscellaneous locations such as the outside of conveyance vehicles.

Last Modified: 06/24/2017
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