Survival and dispersal of horse flies (Diptera: Tabanidae) feeding on cattle sprayed with a sublethal dose of Fenvalerate

A mark-recapture study was undertaken to determine the fate of tabanids feeding on cattle sprayed with a sublethal dose of fenvalerate. A total of 15,465 tabanids belonging to at least 17 species and five genera were marked individually; flies were divided equally between control and fenvalerate-sprayed bullocks. Data were summarized for the four most abundant species: Tabanus fuscicostatus Hine, T. lineola F., T. pallidescens Philip, and T. wilsoni Pechuman. The recapture rate of tabanids was 6.6% for the control and 3.4% for the fenvalerate treatment. When the proportion of flies predicted to die or be unaffected after feeding on the sprayed bullocks was considered, an estimated 75% of the flies exposed to a sublethal knockdown dose survived and attempted to seek a subsequent host. Dispersal of tabanids was not affected by treatment. The recapture data after the first day of marking was significantly delayed for tabanids that fed on fenvalerate-sprayed bullocks.