Evaluation of Host-Derived Volatiles for Trapping Culicoides Biting Midges (Diptera: Ceratopogonidae)

Culicoides biting midges (Diptera: Ceratopognidae) cause pain and distress through blood feeding, and transmit viruses that threaten both animal and human health worldwide. There are few effective tools for monitoring and control of biting midges, with semiochemical-based strategies offering the advantage of targeting host-seeking populations. In previous studies, we identified the host preference of multiple Culicoides species, including Culicoides impunctatus, as well as cattle-derived compounds that modulate the behavioral responses of C. nubeculosus under laboratory conditions. Here, we test the efficacy of these compounds, when released at different rates, in attracting C. impunctatus under field conditions in Southern Sweden. Traps releasing 1-octen-3-ol, decanal, phenol, 4-methylphenol or 3-propylphenol, when combined with carbon dioxide (CO₂), captured significantly higher numbers of C. impunctatus compared to control traps baited with CO₂ alone, with low release rates (0.1 mg h^-1, 1 mg h^-1) being generally more attractive. In contrast, traps releasing octanal or (E)-2-nonenal at 1 mg h^-1 and 10 mg h^-1 collected significantly lower numbers of C. impunctatus than control traps baited with CO₂ only. Nonanal and 2-ethylhexanol did not affect the attraction of C. impunctatus when compared to CO₂ alone at any of the release rates tested. The potential use of these semiochemicals as attractants and repellents for biting midge control is discussed.