Today marks the first meeting of the federal government’s new multi-agency Invasive Species Council, a group that will tackle the mounting problems of exotic plants and animals in the U.S. The more than 50,000 nonnative species in the U.S. cost the economy some $138 billion a year, according to a Cornell University study released last month. The exotic species drive out native ones and are responsible for the tenuous status of 42 percent of the animals and plants on the federal endangered species list, the study found. The Invasive Species Council is charged with developing a plan of action by August 2000.