Tennessee Expands Imported Fire Ant Quarantine Northward to Kentucky Border

Recently, the TN Department of Agriculture expanded the number of counties under Imported Fire Ant (IFA) quarantine.  This is significant for Kentucky as IFA is continuing to move northward and several of the newly quarantined counties are on the KY border. IFA colonies have periodically been found in the Purchase Area of Kentucky, mostly in the Land Between the Lakes region between  Lake Barkley and Kentucky Lake. Thus far, we have been able to avoid an IFA quarantine by treating and killing individual colonies and not allowing IFA to become established in those areas.

Figure 1. Tennessee Counties showing the previous Imported Fire Ant quarantined counties (yellow) and the expanded quarantine area (red). Southern Kentucky counties have been overlayed at the top of the Tennessee map.

Fire Ant Species & Habits

The red imported fire ant (RIFA), Solenopsis invicta, is native to South America and was first found in the U.S. in the 1940s. It spread from its initial introduction and is common throughout much of the Southern U.S. A second species, the black imported fire ant (BIFA), Solenopsis richteri, was introduced into Mobile, AL in 1918 and has a smaller distribution; it has been found in parts of Mississippi, Alabama, Tennessee, Virginia, South Carolina, and Arkansas.  BIFA is more cold-tolerant than RIFA and has been found established further north. Most of the mounds treated in Kentucky have been identified as BIFA; however RIFA has also been identified. These two species can also hybridize in areas where they both occur. The hybrid may be more cold-tolerant.

Both species have a painful sting that results in a light-colored blister with a reddened area encircling the blister.  They clamp on with their powerful jaws and sting victims repeatedly. The reason they are called fire ants is because their venom causes a burning sensation. In sensitive persons, the sting can result in anaphylactic shock. There are some reports that the sting of BIFA is more pronounced than that of RIFA. Besides attacking people, fire ants can attack and sting pets and wildlife. They can also damage seedling corn and soybeans.

Fire ants can have as many 100,000 to 500,000 workers in a colony. They form a raised, soil nest that the sterile workers fiercely defend. We have noticed in Kentucky that the nests are typically in open sunny areas or on south-facing slopes for warmth. They may be found in urban areas, agricultural areas, pastures, and grasslands.

While fire ants can spread locally through their normal mating and dispersal process, they can travel longer distances by hitchhiking in motor vehicles and in or on soil, such as on plants with roots and soil attached, nursery stock, sand, gravel, grass, sod, or soil-moving equipment; additionally, they may be present in hay or on wood that has come in contact with soil. For that reason, the USDA APHIS limits the spread of fire ants by quarantine. They limit the spread of fire ants by requiring inspection and specific treatments for nursery stock, turf, baled hay and straw that have been stored in contact with soil. USDA APHIS also regulates the movement of soil and soil-moving equipment out of quarantine areas.

Kentucky’s Containment Strategy

Our strategy for Kentucky is to identify IFA mounds and treat them as soon as possible so that they do not spread and do not become established. We need people, particularly in southern Kentucky counties along the Tennessee border, to be on the watch for fire ants. The best way to locate fire ants is by visually searching for the raised mounds. If a suspected fire ant mound is found, people should contact their local county Extension office to report the sighting. County agents need to report sightings to the Office of the State Entomologist here at UK. ~ Ric Bessin and Joe Collins for KY Pest News