Crataerina spp. as potential vectors for Trypanosoma sp. in Alpine swifts (Tachymarptis melba)?

MORÉ, G.; BIZE, P.; CIGLER, P.; COLOMINAS, R.; MEIER, C.; HEMPHILL, A.; KELLER, S. A.; FREY, C.F.; BASSO, W.

Zürich

Encuentro; Scientific meeting Swiss Society of Vector Entomology Group (SVEG2023); 2023

Swiss Society of Vector Entomology Group

Hippoboscidae diptera or louse flies (keds) are widely distributed obligatory blood-feeding ectoparasites of birds and mammals. The taxonomic keys for European Hippoboscidae were updated in 2022, and four species were recognized within the Crataerina genus as parasites of Apodiformes and Passeriformes. Alpine swifts (Tachymarptis melba) are Apodiformes affected by louse flies during the nesting season in Switzerland. In recent years, an increased mortality of nestlings has been recorded and a Trypanosoma sp. was microscopically and molecularly identified in blood and tissues of dead or euthanized birds. Louse flies (n=39) were collected from five different Swiss alpine swift colonies and fixed in 70% ethanol. Morphologically, all specimens belonged to the genus Crataerina. Regarding the wing types, both C. acutipennis (n=22) and C. melbae (n=13) were identified, with four individuals showing intermediate wing types. Crataerina acutipennis was found in all five colonies, and C. melbae in four. One specimen was processed by scanning electron microscopy and structures resembling trypanosomes were observed on the flies' ventral surface. Dissected intestines from three Crataerina specimens and surface swabs from five specimens were analyzed for Trypanosoma spp. by 18S-rRNA-PCR and sequencing. One intestine and three swabs resulted positive and the sequences were identical to the obtained from tissues of infected alpine swifts, belonging to the Trypanosoma corvi group. We suspect that Crataerina spp. could be vectors for alpine swift trypanosomas. Furthermore, our findings suggest that C. acutipennis and C. melbae could be a single species since they share the host and intermediate morphological types were found.