MISSISSIPPI STATE -- Mississippi battles well known non-native species such as kudzu and fire ants, but experts say the state is vulnerable to other introduced species.

Known as nonindigenous species, these plants and animals become part of ecosystems outside their native range. According to figures released by Cornell University, non-native species cost the United States more than $122 billion a year, but not all introduced species are harmful.

It is estimated that since Christopher Columbus landed in North American, more than 30,000 species have been introduced. Non-native species such as wheat, rice, cattle and poultry now provide more than 98 percent of the U.S. food supply.

Dave Burrage, marine resources specialist with Mississippi State University's Extension Service, is hoping to use education to help curb the problem of aquatic nuisance species.

"Mississippi probably has at least 30 to 40 introduced species, but some of them are so common people don't know they are not native," Burrage said. "Much of the problem is that these introduced species have no natural predators in their new surroundings, and grow so fast they easily overtake the native species."

Burrage said the Gulf states are particularly vulnerable to introduced pests. Mississippi's mild climate offers a hospitable environment for non-native species. The shipping ports, Mississippi River drainage, the Gulf Coast Intercoastal Waterway and recreation across state borders all provide numerous opportunities for new species to be introduced.

Burrage said the state's top 10 problem species are imported fire ants, kudzu, water hyacinth, hydrilla, boll weevil, cogongrass, Eurasian watermilfoil, nutria, tilapia and zebra mussel.

Hydrilla, Eurasian watermilfoil and water hyacinth are all aquatic plants that can live in fresh and slightly saline water. Hydrilla was introduced from Asia in the 1960s, Eurasian watermilfoil from Europe and Asia in the 1940s and water hyacinth was brought from South America in the late 1800s as an ornamental.

Each of these plants chokes waterways, causes problems with navigation and flood control, and grows so fast it takes over native vegetation.

Cogongrass is a southeast Asian native introduced to the United States in the 1930s. It can grow on any soil type, and chokes out native plant species. It is seen beside many state roads.

Boll weevils and fire ants are natural spreaders. Boll weevils came from Mexico, and fire ants, native to Brazil, were brought into the Port of Mobile shortly after World War I. Fire ants cause painful bites, kill small birds and animals, and damage landscapes and pastures, as well as equipment working in them.

Boll weevils were responsible for about a 1.5 percent cotton yield loss in Mississippi last year worth an estimated $9.7 million. This is down from 1996's estimated loss of 2.6 percent, or $18.7 million. The decrease is attributed to the advances of the boll weevil eradication program.

Nutria, a rodent once valued for its fur, was introduced to South Louisiana from Argentina and Chile in the 1930s. Nutria multiply rapidly and destroys marshes by eating the grass which holds the soil together. They also burrows into levees and under highways.

Zebra mussels got a lot of attention when they arrived in ship ballast water in 1988 in the Great Lakes area and began causing serious problems. Native to Europe's Aral, Caspian and Black Seas, they have spread to 21 states. Zebra mussels clog water intakes and damage navigational structures.

Zebra mussels are found in northern Mississippi, but they have not been able to establish on the Coast. Burrage said this is probably because of high salinity and warm water temperatures.

Tilapia is native to Africa and was introduced in the 1960s for weed control. A popular fish to eat, tilapia is one of the major species produced in the aquaculture industry. In the wild, they displace native fish as they are prolific breeders which aggressively protect their young.

Tilapia are established in many coastal Mississippi rivers, where the warm water temperatures suit them well. They can't survive water temperatures less than 54 degrees for long, so cold winters help limit where this species can spread.

Burrage said introduced species are here to stay, although education and prevention can control them somewhat.

"We're never with physical means going to be able to eradicate or contain these species that have been introduced, but we can slow them down," Burrage said.

Find more information on introduced species at http://msstate.edu/dept/crec/ans.html.