Molecular Detection and Analysis of Trypanosoma (Megatrypanum) spp. Diversity in Tabanidae (Diptera) Collected in Lithuania

Horse flies are known as vectors of various species of trypanosomatids. The aim of this study was to investigate Trypanosoma in the Tabanidae family collected in different localities in Lithuania. Our objectives were to examine the genetic diversity of Trypanosoma sp. detected in tabanids, assessing the relationships between parasite lineages and tabanid species. The present study reports on the molecular detection and genetic diversity of trypanosomes in 10 species of tabanids, with two of them being reported for the first time. The findings suggest that different strains of the T. theileri complex are not related to different tabanid species. Trypanosomatids from the Tabanidae family have not been studied in Lithuania in any detail. In this study, a nested PCR amplifying the DNA fragment coding the SSU rRNA was used to determine the Trypanosoma spp. prevalence and diversity in the Tabanidae family collected in Lithuania in 2018-2019. In total, 101 Tabanidae individuals were investigated from six areas in Lithuania, and 14 different species were identified. The overall positivity of Trypanosoma spp. DNA in tabanids was 50.5% (51/101). Tabanus maculicornis was the most abundant species and yielded the highest prevalence of trypanosomatids (84.62%, 22/26), while Hybomitra nitidifrons showed a high prevalence as well, reaching 77.8% (14/18). In flies of some species (Hybomitra lapponica and Hybomitra lurida), Trypanosoma was detected for the first time. Nine different haplotypes were detected as being distributed in different tabanid species. Analysis showed that most sequences obtained during our study were identical or extremely close to two major T. theileri subclades: TthI and TthII. Our data analysis suggests the presence of different Trypanosoma genotypes in the same tabanid species, meaning that different lineages of Trypanosoma could be more related to the vertebrate host and not the fly species. This is the first study of trypanosomatid parasites in tabanids from Lithuania, and our results are valuable in providing data on the diversity of these parasites in different Tabanidae species.