'A flying start': Wildlife trypanosomes in tissues of Australian tabanids (Diptera: Tabanidae)

Anna-Sheree Krige; R C Andrew Thompson; Allan Wills; Glen Burston; Sian Thorn; Peta L Clode

doi:10.1016/j.meegid.2021.105152

'A flying start': Wildlife trypanosomes in tissues of Australian tabanids (Diptera: Tabanidae)

Infect Genet Evol. 2021 Dec:96:105152. doi: 10.1016/j.meegid.2021.105152. Epub 2021 Nov 22.

Authors

Anna-Sheree Krige¹, R C Andrew Thompson², Allan Wills³, Glen Burston⁴, Sian Thorn⁵, Peta L Clode⁶

Affiliations

¹ UWA School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia. Electronic address: anna-sheree.krige@research.uwa.edu.au.
² School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia 6150, Australia.
³ Department of Biodiversity, Conservation and Attractions (DBCA), Locked Bag 2, Manjimup, Western Australia 6258, Australia.
⁴ Maroo Wildlife Refuge Inc., Southern Forests, 161 Perup Rd, Manjimup, Western Australia 6258, Australia.
⁵ UWA School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
⁶ UWA School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia; Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.

PMID: 34823027
DOI: 10.1016/j.meegid.2021.105152

Abstract

Tabanids (syn. horse flies) are biting-flies of medical and veterinary significance because of their ability to transmit a range of pathogens including trypanosomes - some species of which carry a combined health and biosecurity risk. Invertebrate vectors responsible for transmitting species of Trypanosoma between Australian wildlife remains unknown, thus establishing the role of potential vector candidates such as tabanids is of utmost importance. The current study aimed to investigate the presence of indigenous trypanosomes in tabanids from an endemic area of south-west Australia. A total of 148 tabanids were collected, with morphological analysis revealing two subgenera: Scaptia (Pseudoscione) and S. (Scaptia) among collected flies. A parasitological survey using an HRM-qPCR and sequencing approach revealed a high (105/148; 71%) prevalence of trypanosomatid DNA within collected tabanids. Individual tissues - proboscis (labrum, labium and mandibles, hypopharynx), salivary glands, proventriculus, midgut, and hindgut and rectum - were also tested from a subset of 20 tabanids (n = 140 tissues), confirming the presence of Trypanosoma noyesi in 31% of screened tissues, accompanied by T. copemani (3%) and T. vegrandis/T.gilletti (5%). An unconfirmed trypanosomatid sp. was also detected (9%) within tissues. The difference between tissues infected with T. noyesi compared with tissues infected with other trypanosome species was statistically significant (p < 0.05), revealing T. noyesi as the more frequent species detected in the tabanids examined. Fluorescence in situ hybridisation (FISH) and scanning electron microscopy (SEM) confirmed intact parasites within salivary glands and the proboscis respectively, suggesting that both biological and mechanical modes of transmission could occur. This study reveals the presence of Australian Trypanosoma across tabanid tissues and confirms intact parasites within tabanid salivary glands and the proboscis for the first time. Further investigations are required to determine whether tabanids have the vectorial competence to transmit Australian trypanosomes between wildlife.

Keywords: Biting flies; Infection; Prevalence; Trypanosoma; Vectors; protozoa.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Animals, Wild
Biosecurity
Diptera / parasitology*
Insect Vectors / parasitology*
Trypanosoma / isolation & purification*
Trypanosomiasis / parasitology
Trypanosomiasis / transmission
Trypanosomiasis / veterinary*
Western Australia