Feeding success and trappability of horse flies evaluated with electrocuting nets and odour-baited traps

The relative capacity of different tabanid species to mechanically transmit infectious diseases was assessed by comparing their feeding success on a horse. Ten species were intercepted with electrocuting nets while approaching and leaving the horse: the most abundant were Tabanus pallipennis, Pseudotabanus silvester and Tabanus townsvilli. Of the tabanid species that managed to bite, the highest proportions of partially fed flies, which could potentially transmit pathogens to their next host, were for T. pallipennis (49%) and Dasybasis oculata (48%), while the lowest was in P. silvester (11%). T. townsvilli and T. dorsobimaculatus did not obtain blood meals, possibly because of their sensitivity to host defensive movements. The study also investigated whether catches from odour-baited traps could reliably predict tabanid activity around horses. The traps caught fewer flies, but captured the same species as the electrocuting nets surrounding a horse. A significant linear relationship between the two was observed for P. silvester, T. pallipennis and T. townsvilli but not for T. dorsobimaculatus. The results also demonstrate differences in trappability among tabanid species.