Survival at low temperatures is an important parameter determining distribution of imported fire ants in the United States. Supercooling points and s

Urbanization can alter the organization of ant communities and affect populations of urban pest ants. In this study, we sampled ant communities in urban and suburban yards to understand the habitat factors that shape these communities and influence the abundance of a common pest species, Tapinoma sessile (Say). We used pitfall traps to sample ant communities and a combination of pitfall traps and baiting to collect T. sessile at 24 sites in Knoxville, TN. In total, we collected 46 ant species. Ant species richness ranged from seven to 24 species per yard. Ant species richness tended to be lowest near houses, whereas T. sessile abundance was highest near houses. The best predictors of ant species richness in yards were canopy cover and presence of leaf litter: ant species richness peaked at mid-levels of canopy cover and was negatively correlated with the presence of leaf litter. Tapinoma sessile abundance increased with presence of logs, boards, or landscaping timbers and leaf litter in yards. Our results indicate that ant communities and the abundance of particular pest species in these urban and suburban landscapes are shaped by many of the same factors that structure ant communities in less anthropogenically disturbed environments.

Imported fire ants (Solenopsis spp.; Hymenoptera: Formicidae) occupy 54 counties (~5.4 million ha) in Tennessee. To better understand the fire ant species distribution in Tennessee, the state was divided into 16.1 × 16.1 km grids, and a single colony was sampled for cuticular hydrocarbon and venom alkaloid analyses within each grid. A total of 387 samples was processed from which 9 (2.3%), 167 (43.2%), and 211 (54.5%) were identified as red (Solenopsis invicta Buren), black (Solenopsis richteri Forel), or hybrid (S. invicta × S. richteri) imported fire ants, respectively. The S. invicta was only found near metropolitan Nashville in Davidson and Williamson counties and at one site in Decatur Co. All samples east of Franklin Co. were identified as hybrids. Tennessee counties west of Lincoln were predominantly S. richteri (86.5%) as opposed to hybrid (13.0%) and S. invicta (0.5%). The exception was Hardin Co., which was predominantly hybrid. Counties containing both hybrid and S. richteri (all in the middle and western part of the state) included Bedford, Decatur, Franklin, Giles, Hardeman, Hardin, Haywood, Lawrence, Lincoln, Marshall, Maury, McNairy, Perry, and Wayne. The S. invicta samples collected from one Williamson Co. site were determined to be polygyne and infected with the Solenopsis invicta virus (genotype SINV-1 A). This was the first detection of polygyne imported fire ant in Tennessee. The SINV-1 A virus was also a new find at the time of detection, but has been previously reported. The survey results are being used to direct current and future biological control efforts against imported fire ants in Tennessee.

Boric acid-sucrose water baits were evaluated in the laboratory for toxicity, consumption, and efficacy against the red imported fire ant, Solenopsis invicta Buren. Over the dosage range from 0.02 to 1.0% boric acid, LC₅₀s (95% CL) ranged from 1.27% (1.05- 3.88%) at 3 d to 0.11% (0.09-0.13%) at 8 d. Amount of bait consumed was related inversely to the concentration of active ingredient. High concentrations of boric acid bait (5%) were consumed at a lower rate than the control (10% sucrose water). In large fire ant colonies exposed continuously to 4 concentrations (0.25, 0.5, 0.75, 1.0%) of boric acid bait, workers and brood were reduced by 90% at 6 wk. Therefore, low concentrations of boric acid are necessary for delayed toxicity and reduced repellency.