MONITORING AND MANAGEMENT OF RED IMPORTED FIRE ANTS IN A TROPICAL FISH FARM

Abstract

Tropical fish farms provide a prime habitat for the red imported fire ant, Solenopsis invicta Buren, which is an invasive, stinging ant that has spread throughout the southern United States. Stings can be a serious health hazard to hypersensitive individuals, and the presence of large populations can interfere with operational activities. The most efficient method of controlling fire ants is the application of ant bait. However, most fish farmers are reluctant to use baits or other chemical methods of control because of the unknown risk to fish. Baited stations in combination with maps generated by geographical information system software were used to estimate locations of fire ant nests. Maps of estimated fire ant locations encompassed from 10 to 100% of actual fire ant nests surveyed when there was a minimum of a single fire ant within a station. Low percentages of overlap between mapped areas and fire ant nests were associated with low nest densities and when higher ant count thresholds were used to indicate positive stations. Ant bait containing the insect growth regulator methoprene was broadcast between ponds, with some unavoidable bait entry into ponds. Fire ant nest densities declined 57% within 4 months. In contrast, nest densities increased 86% in untreated areas. During the summer, fire ant populations declined an average of 68% and increased 110% for treated and untreated areas, respectively. Fire ant nest densities and populations began to increase by December in both treated and untreated areas. No obvious fish mortality related to the ant baiting was noted during the study.