Molecular Detections of Hematoparasites in Tabanids (Diptera: Tabanidae) from Northeastern Thailand

Tabanid flies (Diptera: Tabanidae) are important pests and potential vectors of various pathogens affecting humans and animals. However, information on their vectorial roles in Thailand remains limited. In this study, we employed molecular methods to screen for filarial nematodes and hemoparasites in four tabanid species collected from northeastern Thailand. A total of 246 specimens representing Chrysops dispar Fabricius, Tabanus rubidus Wiedemann, T. megalops Walker, and T. striatus Fabricius were examined. No filarial parasites were detected. However, three specimens-one from each Tabanus species-tested positive for Trypanosoma. Analysis of ITS1/5.8S rRNA/ITS2 sequences revealed that the detected Trypanosoma were most closely related to the T. theileri complex, showing >98% sequence similarity. Phylogenetic analyses further indicated that the T. theileri complex detected in this study clustered with T. theileri lineage II (TthII). Additionally, one specimen of T. megalops tested positive for Anaplasma, with 16S rDNA sequences showing 99.76% similarity to A. platys. To our knowledge, this is the first report of the T. theileri complex in T. megalops, T. rubidus, and T. striatus, suggesting that these species may serve as potential mechanical carriers of these pathogens.