But readers of Biological Invasions: Economic and Environmental Costs of Alien Plant, Animal, and Microbe Species (CRC Press, 2002) won't want to tarry too long. An estimated 50,000 "exotics" are causing tens of billions of dollars in harm each year in the United States, according to the new book, and more are on the way. And they're not arriving via spaceships, but in the thousands of aircraft and sea-going ships in everyday commerce, the authors observe.
The book covers many of the more than 120,000 non-indigenous species that have invaded six countries (the United States, United Kingdom, Australia, India, South Africa and Brazil) and gives special emphasis to globe-traveling exotic diseases before making recommendations to help nations slow the influx.
"The impact of invasive species is second only to that of human population growth and associated activities as a cost of loss of biodiversity throughout the world," says Pimentel, a professor emeritus in Cornell's College of Agriculture and Life Sciences. "In the United States, invasions of non-native plants, animals and microbes are thought to be responsible for 42 percent of the decline of native species now listed as endangered or threatened." The names of some invading species are threatening enough. For instance, giant hogweed, a perennial herb in Britain, is blamed for serious dermatitis when it contacts skin. Root-rot fungus is a plant disease spread through Australia by feral pigs, which themselves are non-native down under. Paterson's curse, a weed that invaded Australian pastures, sickens sheep by damaging their livers with plant toxins. Yet the screw-worm fly is a curse to cattle in tropical regions everywhere in the world -- except Australia.