First record of Trypanosoma evansi DNA in Dichelacera alcicornis and Dichelacera januarii (Diptera: Tabanidae) flies in South America

Abstract

Background Trypanosoma evansi infects a large number of wild and domestic animals and causes a spoliative disease known as surra. It is mechanically transmitted, mainly by biting flies of the genera Tabanus and Stomoxys. The detection of T. evansi DNA in the feeding apparatus of Dichelacera alcicornis and Dichelacera januarii from South America is reported, to the best of our knowledge, for the first time. Methods Tabanids were collected weekly from February 2018 to February 2019 from two sites. The feeding apparatus was removed and DNA extraction, polymerase chain reaction and sequencing were performed. Results A 205-base pair fragment of the variant surface protein RoTat 1.2 gene, confirmed by DNA sequencing, was amplified from the feeding apparatus of D. alcicornis and D. januarii. Conclusions This is, to the best of our knowledge, the first record of T. evansi DNA in South American tabanids. Graphical abstract

Discrimination of cryptic species: Tabanus triangulum and Tabanus occidentalis (Diptera: Tabanidae) differ in size and shape

“…Tabanidae (horse flies) comprise approximately 4,525 species ( Pape & Thompson, 2023 ), of which 27% are found in the Neotropical region ( Henriques et al, 2012 ). Several species are mechanical vectors of pathogens to humans and animals ( Baldacchino et al, 2014 ; Taioe et al, 2017 ; Bilheiro et al, 2019 ; Rodrigues et al, 2021 ; 2022 ; Ramos et al, 2023 ). Tabanid studies have focused on females because, since they need a blood meal before ovipositing, they are the vectors of pathogens ( Barros, 2001 ; Rafael & Charlwood, 1980 ).…”

Tabanidae (Diptera) collected on horses in a Cerrado biome in the state of Tocantins, Brazil

“…Ecological studies in the same area showed that the activity peak of adult insects occurred in the hottest periods of the year (late spring and summer) and suggested that Tabanus triangulum Wiedemann, 1828 was a strong candidate for the mechanical transmission of pathogens in the region, due to its prevalence there ( Krüger & Krolow, 2015 ). Recently, Trypanosoma evansi DNA was found in the mouthparts of Dichelacera alcicornis (Wiedemann, 1828) and D. januarii (Wiedemann, 1819) ( Ramos et al, 2023 ) in the state of Santa Catarina (first record for South America). In the Pantanal biome, Barros (2001) noticed that the rainy season offers the highest risk of mechanical transmission of pathogenic agents by tabanids.…”

Tabanidae (Diptera) captured on horses in the Cerrado biome of Tocantins, Brazil.

“…Ecological studies in the same area corroborate that the activity peak of adult insects occurs in the hottest periods of the year (late spring and summer) and suggest that Tabanus triangulum Wiedemann, 1828 is a strong candidate for the mechanical transmission of pathogens in the region, due its prevalence there (Krüger and . Recently, Trypanosoma evansi DNA was found in the mouthparts of the tabanids Dichelacera alcicornis (Wiedemann, 1828) and D. januarii (Wiedemann, 1819) (Ramos et al 2023) in the state of Santa Catarina ( rst record for South America). In the Pantanal biome, Barros (2001) noticed that the rainy season offers the highest risk of mechanical transmission of pathogenic agents by tabanids.…”