Biological Invasions

, Volume 14, Issue 4, pp 797–812 | Cite as

Trade-associated pathways of alien forest insect entries in Canada

  • Denys YemshanovEmail author
  • Frank H. Koch
  • Mark Ducey
  • Klaus Koehler
Original Paper


Long-distance introductions of new invasive species have often been driven by socioeconomic factors, such that traditional “biological” invasion models may not be capable of estimating spread fully and reliably. In this study we present a new methodology to characterize and predict pathways of human-assisted entries of alien forest insects. We have developed a stochastic quantitative model of how these species may be moved with commodity flow through a network of international marine ports and major transportation corridors in Canada. The study makes use of a Canadian roadside survey database and data on Canadian marine imports, complemented with geo-referenced information on ports of entry, populated places and empirical observations of historical spread rates for invasive pests. The model is formulated as a probabilistic pathway matrix, and allows for quantitative characterization of likelihoods and vectors of new pest introductions from already or likely-to-be infested locations. We applied the pathway model to estimate the rates of human-assisted entry of alien forest insect species across Canada as well as cross-border transport to locations in the US. Results suggest a relatively low nationwide entry rate for Canada when compared to the US (0.338 new forest insect species per year vs. 1.89). Among Canadian urban areas, Greater Toronto and Greater Vancouver appear to have the highest alien forest insect entry potential, exhibiting species entry rates that are comparable with estimated rates at mid-size US urban metropolises.


Pathway analysis Invasive species International trade Freight transport Human-assisted entry Long-distance spread 



The authors extend their gratitude and thanks to Kirsty Willson, Marty Siltanen (Natural Resources Canada) and Ryan McMillan (Ontario Ministry of Natural Resources) for technical support and diligence with preparing the Canadian roadside database and helping undertake the pathway modeling study; Marcel Dowson, Julia Dunlop and Annie Baxter (Canadian Food Inspection Agency) for help with acquiring the Canadian roadside database; and Roger Magarey (North Carolina State University) and Joseph Cavey (USDA APHIS) for help with accessing the PestID database. The participation of Denys Yemshanov was supported by interdepartmental NRCan—CFIA Forest Invasive Alien Species initiative. The participation of Frank Koch was supported by Research Joint Venture Agreements #09-JV-11330146-087 and #10-JV-11330146-064 between the USDA Forest Service, Southern Research Station, Asheville, NC and North Carolina State University. The participation of Mark Ducey was supported by the Agriculture and Food Research Initiative Competitive Grants Program Grant No. 2010-85605-20584 from the National Institute of Food and Agriculture.

Supplementary material

10530_2011_117_MOESM1_ESM.doc (690 kb)
Supplementary material 1 (DOC 690 kb)


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Copyright information

© Her Majesty the Queen in Right of Canada 2011

Authors and Affiliations

  • Denys Yemshanov
    • 1
    Email author
  • Frank H. Koch
    • 2
  • Mark Ducey
    • 3
  • Klaus Koehler
    • 4
  1. 1.Natural Resources Canada, Canadian Forest ServiceGreat Lakes Forestry CentreSault Ste. MarieCanada
  2. 2.USDA Forest Service, Southern Research StationEastern Forest Environmental Threat Assessment CenterResearch Triangle ParkUSA
  3. 3.Department of Natural Resources and the EnvironmentUniversity of New HampshireDurhamUSA
  4. 4.Canadian Food Inspection AgencyOttawaUSA

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