Comparisons of antifeedancy and spatial repellency of three natural product repellents against horn flies, Haematobia irritans (Diptera: Muscidae).

BACKGROUND Horn flies are among the most important biting fly pests of cattle in the United States. Horn fly management is largely dependent upon pesticides, which ultimately leads to the rapid development of insecticide resistance. Alternative control strategies, including repellents, have shown promising results in reducing fly biting. In the present study, we examined the efficacy and longevity of recently identified natural product repellents against horn flies. RESULTS Catnip oil, geraniol and C8910 acids reduced horn fly feeding in a laboratory bioassay and also exhibited spatial repellency in the olfactometer. Residual activity was observed for up to 3 days in laboratory assays; however, 24 h of residual effectiveness was observed from the two repellents when applied on cattle in the field. The limited residual effectiveness was correlated with the high volatility of the major active repellent compounds. CONCLUSION All three natural product repellents effectively repel biting horn flies, exhibiting both feeding deterrence and spatial repellency. They may be used for developing an effective push-pull strategy with a slow release matrix that can prolong their effectiveness for horn fly management.