Biological Control Considerations for Imported Fire Ants in Cattle Production

• Introduction
• The Problem

• Costs of the Problem
• Costs of Control
• Regulatory Considerations
• Biological Control Considerations

• Developing a Management Plan
• Bait Basics
• Individual Mound Treatments
• More Information
• Disclaimer
• Contributors
• Print this Lesson

One reason imported fire ants are so abundant in the United States is that their specific natural enemies, which help keep their population levels in check, were left behind in their native South America. Researchers across the Southeast are committed to introducing biological control agents to help provide sustainable suppression of imported fire ants.

A phorid fly, Pseudacteon curvatus. Photo by Bart Drees.

Fire ant decapitated by phorid fly. Photo by Sanford Porter, USDA.

Species of parasitic flies called phorid flies (from the fly’s scientific family name, Phoridae, in the insect order Diptera), have been released in infested areas of the southern United States. These species include Pseudacteon tricuspis, P. curvatus, and P. litoralis and will possibly include others in the future.

Microbial pathogen Thelohania solenopsae.

A disease of fire ants called Thelohania is also being established and monitored. Although the impact has yet to be documented, these organisms are capable of sustaining themselves in the environment and of spreading naturally. They are expected to help suppress imported fire ant colonies to some degree. The effect is expected to be similar to that of hot, dry environmental conditions that frequently cause a decline in fire ant populations.

Fire ants do have some natural enemies in the United States. Other ant species, for example, are important predators of imported fire ant queens. They can raid and destroy small imported fire ant colonies and compete for nesting sites and resources. Preservation of these competitor ant species, in addition to conserving introduced and native biological control organisms, will help provide biological resistance to prevent the formation of high densities of imported fire ants. To preserve these competitor species, avoid chemical treatment where populations are historically low, such as fewer than 20 ant mounds per acre. Spot treatment of nuisance mounds in these areas may still be necessary.