UT's Energy, Environment
and Resources Center Presents
Smoky Mountain
Resource Issues in Great Smoky Mountains National Park
SIGHTLINE
SPRING/SUMMER 2003
Vol. 4 No. 1
SITE LOCATOR MAPFOR GSMNP STORIES
HUMAN INTERACTION Elkmont in the Balance
***
Editor: David Brill; Assistant Editor: Constance Griffith; Writers: Kris Christen, Lisa Byerley Gary, Elise LeQuire, Dennis McCarthy, and Becky Nichols. Graphic Designer: Lisa Byerley Gary.
SIGHTLINE is published on behalf of
Great Smoky Mountains National
Park
by the
Energy, Environment and Resources
Center (EERC)
at the
University of Tennessee.
EERC conducts research designed to promote real-world solutions to problems in the fields of energy, environment, technology, and economic development.
For additional information, write EERC, 311 Conference Center Building, The University of Tennessee, Knoxville, TN 37996-4134, call 865-974-4251, or visit our Web site at http://eerc.ra.utk.edu.
SIGHTLINE is sponsored by:
and
The
Invading Red ArmyRed imported fire ants are the latest in a long string
of invasive pests to arrive in Great Smoky Mountains National Park.BY KRIS CHRISTEN
Consequently, it was only a matter of time before the red imported fire ant breached the boundaries of Great Smoky Mountains National Park, says Glenn Taylor, a park service biologist. And sure enough, they were sighted just last year along the Foothills Parkway near Tennessee Route 129.
WHAT’S AT STAKE?
These tiny insects can wreak havoc on an ecological community. When a new colony starts up, the foragers feed on sugars, attacking young saplings and seedlings and destroying buds and developing fruits, according to Taylor. Once established, they become protein feeders.
While other insects seem to be their preferred food, particularly other native ant species, red imported fire ants will kill or feed on anything that lives on the ground, including ground nesting birds, rodents, snakes, and even newborn livestock, says Karen Vail, an associate professor with the University of Tennessee’s Entomology and Plant Pathology Department. In the latter cases, their victims generally don’t move all that well yet, and the ants start attacking, stripping them clean. Eventually, "they can change the entire diversity in an area, becoming the dominant terrestrial arthropod," Vail says.
Red imported fire ants build their mounds in almost any type of soil, but they prefer sunny, disturbed areas. "They’re often found along roadsides, pull-offs, overlooks, and open areas, which are also places that people are attracted to," Taylor says. And once disturbed, "they’re very willing to come out and attack just about anything en masse," stinging repeatedly. Symptoms of a fire ant sting include localized burning and itching, with white pustules forming within a day or two. In hypersensitive individuals, the stings can produce severe allergic reactions.
So far, the ants have gained a known foothold only along the Foothills Parkway, but they could easily be residing in other areas of the Park, too, Taylor notes. Entomologists doing moth and butterfly work in Cades Cove reported seeing them there in February 2002, but on repeated follow-up visits, Taylor was unable to locate any colonies. "I think the entomologists were there shortly after the field was burned, leaving it all open, but it grew back quickly, and fire ants don’t like that, so they may have abandoned the area or died," he explains.
PERMANENT CONTROLS ELUSIVE
The park service treats all fire ant mounds that it finds, but it’s an ongoing process and likely to be a long, drawn-out battle. Treatment methods involve using poison bait that the foraging ants will take down into the colony and pass around. If the colony’s not too big, this method works pretty well.
If, on the other hand, the colony’s already well established and deep into the ground, "they tend to pass any food through themselves before they feed the queen, thereby keeping the queen from ingesting anything bad," Taylor says. For that reason, with the bigger mounds, the park service is considering a two-step approach, first using the baits and then drenching the mounds with an insecticide that leaches down and coats the ants.
All of these efforts offer a temporary solution at best because fire ants tend to rapidly reinvade previously treated areas. Making the ants difficult to locate and kill, they often swarm in their winged reproductive stage, floating in the air where the queens mate before settling down to produce new colonies just a short distance away, Taylor says. Compounding the problem, "by the time you realize you have fire ants, there are usually many more nests close by that are so small, we don’t necessarily see them," Vail adds.
Moreover, the baits themselves are notoriously fickle. "There are lots of little details you need to watch out for when you’re using baits," says Vail. For instance, they can’t be applied when the ground is wet such as after a rain or when morning dew still persists. And they must be applied when the outside temperatures are between 70 degrees and 90 degrees F because that’s when ants forage; if it’s too hot, Vail says, the ants remain down in their mounds and won’t feed on the baits. Also, most of the baits have active ingredients that are susceptible to ultraviolet degradation, so they have to be applied during the late afternoon or early evening.
While biological control agents such as phorid flies might offer more permanent method of fire ant suppression, research in this area is incomplete. For now, the Park Service will continue to treat any colonies it finds, but "there’s lots of territory out there, and we can certainly miss some of them," Taylor says.
On a more encouraging note, the Park doesn’t offer the best of habitats for fire ant colonies because most of it is heavily forested. "This species may indeed spread quickly in areas that are open and disturbed, but it’s not expected that they will inhabit the deep forest," says Becky Nichols, a Park Service entomologist.
For more information, contact Glenn Taylor, Great Smoky Mountains National Park, 107 Park Headquarters Road, Gatlinburg, TN 37738, or call 865-430-4748.
