Examples of pathogen pollution are many and dramatic.
Europeans grazed cattle in African savannas, thereby introducing rinderpest, which resulted in massive losses of native African animals and changes to an entire ecosystem.
The import of Japanese chestnuts to the U.S. led to the introduction of chestnut blight, which nearly eradicated American chestnuts.
An international trade in and transport of infected timber spread Dutch elm disease throughout North America, Europe and Southwest Asia.
In the case of amphibians and reptiles, millions of kilograms of the animals may be shipped across the U.S. border each year.
"Many of them are not coming alone," says Picco. "They've got company: ranaviruses and Bd."
Waterdogs have been used as bait for at least 40 years. In 1968, 2.5 million tiger salamander larvae were sold as bait in the lower Colorado River area alone. Waterdogs in that one year were worth $500,000, equivalent to $2,766,489 in 2005 after adjusting for inflation.
"Since the tiger salamander bait trade isn't regulated or controlled in most areas of the western United States," says Picco, "there's no information about the number of individuals collected or traded annually."
She and Collins used the Web site www.baitnet.com to find a listing of bait shops in Arizona. Fourteen shops sold waterdogs, all of which were sampled in their study. The scientists collected 30 waterdogs per bait shop each month, or as often as the salamanders were available.
From March to October of 2005, 85 percent of Arizona bait shops sampled sold at least one ranavirus-infected tiger salamander.
In 2006, ranaviruses were detected in the tiger salamander bait trade between May and October in Arizona, New Mexico and Colorado, but were not found in the few bait
|Contact: Cheryl Dybas|
National Science Foundation