A caution regarding fire ant repellant development

The red imported fire ant, Solenopsis invicta Buren is a significant pest ant to human health, agriculture, and wildlife. Synthetic insecticides have been commonly used in fire ant management, a source of environmental pollution. In order to reduce insecticide applications, there has been increasing interest in the research and development of alternative control tactics, such as fire ant repellants. Repellants could be used to exclude red imported fire ants from some sensitive areas, such as schools and hospitals. Eucalyptol is a common insect repellant. It showed significant repellency toward red imported fire ants at 100 mg/kg; however, it showed attractiveness at 10 mg/kg. This observation gives us a strong warning about using eucalyptol as a repellant against fire ants, because the opposite effect may occur after its concentration is reduced to a certain level. It also indicates that before a judgment can be made on a compound about its potential application as a fire ant repellant, it is necessary to test its effect at very low concentrations. Certainly, a compound repelling ants at high concentrations but attracting them at low concentrations cannot be used as a repellant in fire ant management.