Statewide Survey of Imported Fire Ant (Hymenoptera: Formicidae) Populations in Tennessee

Imported fire ants (Solenopsis spp.; Hymenoptera: Formicidae) occupy 54 counties (similar to 5.4 million ha) in Tennessee. To better understand the fire ant species distribution in Tennessee, the state was divided into 16.1 x 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 x 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-1A). This was the first detection of polygyne imported fire ant in Tennessee. The SINV-1A 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.