Alien species cost the United States $123 billion a year

By Roger Segelken

ANAHEIM, Calif. -- A few bad actors among the more than 30,000 non-indigenous species in the United States cost $123 billion a year in economic losses, Cornell ecologists estimate.

"It doesn't take many trouble-makers to cause tremendous damage," ecologist David Pimentel said of a list that runs from alien weeds (cost: $35.5 billion) and introduced insects ($20 billion) to human disease-causing organisms ($6.5 billion) and even the mongoose ($50 million). Aside from economic costs, he added, more than 40 percent of species on the U.S. Department of the Interior's endangered or threatened species lists are at risk primarily because of non-indigenous species.

Pimentel, who presented his findings this week at the annual meeting of the American Association for the Advancement of Science noted, however, that "most introduced species of plants, animals and microorganisms have become widely accepted and even beneficial participants in our lives."

The damage report, "Environmental and Economic Costs Associated with Non-indigenous Species in the United States" by Pimentel, a professor in the College of Agriculture and Life Sciences, and by Cornell graduate students Lori Lach, Rodolfo Zuniga and Doug Morrison, was presented in a session on environmental science and philosophy. The researchers also acknowledged that 98 percent of the U.S. food supply comes from such introduced species as wheat, rice, domestic cattle and poultry with a value of more than $500 billion a year.

However, even the introduced food sources have alien enemies, such as the mongoose, brought to Puerto Rico and Hawaii in the late 1800s, supposedly to kill rats in sugarcane plantations. The islands still have rats, but the mongooses are preying on native ground-nesting birds and on amphibians and reptiles that could, themselves, be beneficial for pest control.

Meanwhile, the United States has become the land of a billion rats, most of them the introduced Rattus rattus (also known as the European, black or tree rat) and Rattus norvegicus (variously called the Asiatic, Norway or brown rat). Rats on poultry farms and other farms number about 1 billion and each rat destroys grain and other goods worth $15 a year, Pimentel said.

Many introduced species seemed like a good idea at the time, Pimentel said:

·Purple loosestrife (Lythrum salicaria) was introduced from Europe as an ornamental plant in the early 1800s. Loosestrife now invades wetlands in 48 states at an estimated cost of $45 million a year for control and loss of forage crops, crowding out 44 native plants and endangering the wildlife that depend on the native plants.

·When the English sparrow (Passer domesticus) was intentionally introduced to the United States in 1853, it was supposed to control canker worms. Instead, the hardy little bird became a pest by eating crops, displacing some native birds and harassing others and carrying 29 diseases that affect humans and domestic animals. And canker worms still bedevil gardeners.