For Release FA-APR-04

April 19, 2000
NATIVE ANT SPECIES: HEROES IN THE WAR ON FIRE ANTS
Contact: Nathan Riggs, (210) 467-6575, n-riggs@tamu.edu

San Antonio- Ants that invade homes, strip the leaves from crepe myrtle trees, or sting children, have many Texans reverting to the old adage the only good ant is a dead one. This isn't necessarily true, according to Nathan Riggs, county Extension agent for the Integrated Pest Management program in Bexar County, who says not all ants are enemies.

"Many of the ant species we find in our yards provide a service that goes without notice. They compete with and, in some cases, kill imported fire ant colonies in our lawns and native areas. Overall, ants are pretty beneficial creatures," Riggs said. "Fire ants have become a force of nature because they out-compete most other ant species for food and shelter."

The imported fire ant found in Texas was imported to the United States from South America in the late 1920s. One consequence this sudden introduction is that they lack natural enemies here. This lack of parasites, predators, and diseases of these ants has made it easy for imported fire ants to become the dominant specie in much of the southeast. Over-grazed pastures, over-use of insecticides, and expansion of urban areas into rural locations can also provide ideal conditions for fire ant dominance in the ecosystem.

"That's where native ants fit in," Riggs said. "If given an even chance, native ants can compete with low populations of imported fire ants."

A few species, some common and some not, can kill very small fire ant colonies or newly-mated queens that are searching for places to dig into the ground and start their colonies. For example, the crazy ant (Paratrechina longicornis), is a small, long-legged black ant named for its high-speed locomotion and erratic trails. As with the pavement ant (Tetramorium spp.) and little black ant (Monomorium minimum), the worker ants are instrumental in killing fire ant queens searching for nest sites.

The garden, or blue cheese ant (Forelius spp.), is a small orange or brownish ant that runs very rapidly and is commonly seen on the ground in trails that resemble high speed "superhighways." The ground around the nest of this ant is commonly littered with the dead bodies of fire ant workers.

While research has shown that native ants compete with fire ants, it is also evident that many imported fire ants do not compete with each other. Shoveling one imported fire ant mound onto another will not cause a war between the two colonies. Most red imported fire ant colonies in Texas contain multiple queens. These multiple queen colonies are tolerant of each other and do not compete for food or territory. Therefore, shoveling two of these mounds together may only result in one large colony that will move off and begin the rebuilding process together.

Some areas of Texas still harbor native fire ant species which are generally single-queen in nature. These colonies will compete with the imported fire ants for food and territory. In most places, however, these native fire ants are now few and far between.

Researchers are currently trying to learn more about these ant interactions. Asha Rao in Dr. Brad Vinson's laboratory at Texas A&M University is a graduate student studying ant biology and behavior with help from the Texas Imported Fire Ant Research and Management Plan.

"Don't expect these native ant species to eliminate the imported fire ant, but rather to provide competition for food and territory that has traditionally been absent in heavily infested areas," Riggs said.

"The long term vision for suppressing heavy invasions of imported fire ants is to exploit natural enemies and competitors. In the long run, it will be natural enemies that will assist man's efforts to suppress populations of imported fire ants to levels where they will not cause as many problems as they do now."

Until the natural enemy numbers are strong enough to show results, insecticides still provide a ready, reliable tool for fire ant management. Insecticides should be used to treat individual mounds for average lawns with less than 5 mounds and land with less than 20 mounds per acre. In more heavily invested areas, broadcasting bait-formulated products will be more cost-effective and environmentally sound.

"This approach isolates insecticides to the fire ant mound area and does not kill those native, desirable ants that may be present to provide assistance in suppressing fire ant invasions," said Riggs. "The best choice for mound treatments is simple: use a mound treatment that has been successful for you in the past."

For more information on native ants or fire ant management procedures contact your local county Extension agent or visit the Texas Imported Fire Ant Research and Management Plan web site at http://fireant.tamu.edu.

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