Updated 01/16/09

In the last century, the ever-increasing movement of people and resources around the globe has also produced an exchange of exotic organisms . . . mixing and blending the world's plants and animals faster than ever in world history.

Port of Tacoma, Washington Photos courtesy of USDA APHIS PPQ Archive, USDA APHIS PPQ, Bugwood.org

This exchange is most intense in relation to agriculture, where most crops in trade are exotic species, and every commodity has an associated complex of pests and predators. Expanding global commodity trade can provide pests and predators with pathways to new, previously inaccessible, habitats . . . habitats where co-evolved native predators and diseases don't exist to keep populations in check. Expanding global trade is a road to economic growth, but also an economic liability when potentially disastrous exotic pests and diseases find new pathways along that road. These new pathways can be hard to identify and difficult to control.

By far the most problematic group of exotic organisms is the insects. This is due to their diversity in natural and agricultural settings on all continents, their ability to fly, their often-cryptic appearance, and the ability of many to lie dormant for long periods.

Citrus longhorned beetle, an introduced pest that arrived undetected in a shipment of live trees, and the damage it causes.