Acceptance of fire ant baits by nontarget ants in Florida and California

Authors: Oi, David; Atchison, Rachel; HENKE, JENNIFER - Coachella Valley Mosquito And Vector Control District

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Red imported fire ants, or fire ants, are an invasive species which can be efficiently controlled with fire ant baits. A major concern with baiting is the rapid reinfestation of areas previously cleared of fire ants. One strategy to delay or prevent reinfestations is to conserve other ant species that can outcompete reinfesting fire ants. To facilitate the development of this strategy, acceptance of commercial fire ant baits by nontarget ants was examined in Florida and California. In Florida, eight fire ant baits were screened for bait acceptance among four non target ants: the bicolor trailing ants, a pyramid ant, a big-headed ant, and Florida harvester ants. The proportions of the total number of ants that accepted baits per species were not statistically different among the eight fire ant baits. Among all the baits and Florida ants evaluated, Extinguish Pro and Siesta fire ant baits had the lowest average percentages of bait acceptance which prompted further testing. In California testing, the large-sized bicolored pyramid ants and California harvester ants each accepted the five baits. In contrast, the small-sized bicolored pyramid ant and a honeypot ant had minimal or no bait acceptance, respectively. Forelius pruinosus and a species from the Pheidole crassicornis group had inconsistent bait acceptance. None of the fire ant bait products tested exhibited non-acceptance by all non-target ant species. To conserve nontarget ants, fire ant bait selection will need to consider the nontarget ants present at individual sites.

Technical Abstract: Red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae) infestations can be cleared from areas with baits, but these areas are often reinfested. To facilitate biotic resistance strategies to reinfestation, acceptance of eight commercial fire ant baits by nontarget ants was examined in Florida and California. In Florida, the baits Advion; Amdro Pro; Antixx; Clinch; Esteem; Extinguish Pro; Extinguish Plus; and Siesta were tested on Monomorium floricola (Jerdon), Dorymyrmex bureni (Trager); Pheidole megacephala (Fabricius); and Pogonomyrmex badius (Latreille). The proportions of the total number of ants that accepted baits were not statistically different among the eight fire ant baits by species. Among all the baits and Florida species evaluated, Extinguish Pro and Siesta had the lowest average percentages of bait acceptance (0.7 and 1.6, respectively). In California, tests were conducted with, Pogonomyrmex californicus Buckley, large and small-sized Dorymyrmex bicolor Wheeler, Forelius pruinosus Roger, a species from the Pheidole crassicornis group, and a Myrmecocystus sp. Significant differences in bait acceptance for each species were not detected among the five baits tested (Advion, Esteem, Extinguish Pro, Extinguish Plus, and Siesta). Based on mean proportions of bait acceptance and observations of bait feeding, there was inconsistent bait acceptance by Forelius pruinosus Roger and Pheidole crassicornis group, and Myrmecocystus sp. did not accept any fire ant bait. None of the fire ant bait products tested exhibited non-acceptance by all, non-target ant species. To conserve nontarget ants, fire ant bait selection will need to consider the nontarget ants present at individual sites.