Diversity and seasonality of horse flies (Diptera: Tabanidae) in Uruguay

Horse flies (Diptera: Tabanidae) are hematophagous insects that cause direct and indirect losses in livestock production and are important vectors of pathogens. The aim of this study was to determine the diversity and seasonality of horse fly species at an experimental farm in Tacuarembó and the diversity of species in different departments of Uruguay. For 20 months, systematic collections were performed using Nzi and Malaise traps in two different environments at the experimental farm. Temperature, humidity and rainfall were recorded using a local climatological station. In addition, nonsystematic collections were made at farms located in the departments of Paysandú, Tacuarembó and Colonia. A total of 3,666 horse flies were collected, allowing the identification of 16 species. Three species were recorded for the first time in Uruguay: Dasybasis ornatissima (Brèthes), Dasybasis missionum (Macquart), and Tabanus aff. platensis Brèthes. A species that had not been previously taxonomically described was identified ( Tabanus sp.1). In the systematic captures, the most abundant species were Tabanus campestris Brèthes, T. aff. platensis and D. missionum , representing 77.6% of the collected specimens. The environment was an important factor related to the abundance of horse flies, as well as the mean temperature. The horse fly season in Tacuarembó started in September and ended in May, with three evident peaks, the most important one during summer. No horse flies were caught during winter. Variations in the prevalence of species in the different departments were observed, indicating the need to carry out new sampling efforts in different areas.