Louse flies of Eleonora’s falcons that also feed on their prey are evolutionary dead‐end hosts for blood parasites

Abstract

Host shifts are widespread among avian haemosporidians, although the success of transmission depends upon parasite‐host and parasite‐vector compatibility. Insular avifaunas are typically characterized by a low prevalence and diversity of haemosporidians, although the underlying ecological and evolutionary processes remain unclear. We investigated the parasite transmission network in an insular system formed by Eleonora's falcons (the avian host), louse flies that parasitize the falcons (the potential vector), and haemosporidians (the parasites). We found a great diversity of parasites in louse flies (16 Haemoproteus and 6 Plasmodium lineages) that did not match with lineages previously found infecting adult falcons (only one shared lineage). Because Eleonora's falcon feeds on migratory passerines hunted over the ocean, we sampled falcon kills in search of the origin of parasites found in louse flies. Surprisingly, louse flies shared 10 of the 18 different parasite lineages infecting falcon kills. Phylogenetic analyses revealed that all lineages found in louse flies (including five new lineages) corresponded to Haemoproteus and Plasmodium parasites infecting Passeriformes. We found molecular evidence of louse flies feeding on passerines hunted by falcons. The lack of infection in nestlings and the mismatch between the lineages isolated in adult falcons and louse flies suggest that despite louse flies’ contact with a diverse array of parasites, no successful transmission to Eleonora's falcon occurs. This could be due to the falcons’ resistance to infection, the inability of parasites to develop in these phylogenetically distant species, or the inability of haemosporidian lineages to complete their development in louse flies.

Avian Haemosporidian Diversity on Sardinia: A First General Assessment for the Insular Mediterranean

“…In nine host species, we did not observe any infections, and, although the number of birds sampled in some species was low, the negative results from Caprimulgus europaeus, Dendrocopos major, Lullula arborea, Regulus ignicapilla, and Curruca sarda is consistent with there being no molecular evidence of infections recorded to date (see MalAvi).We identified for the first time a haemosporidian parasite infection in four species: Muscicapa tyrrhenica, Saxicola rubicola, Carduelis corsicana and Lanius senator. For the latter species, a previous association was indirectly related to louse flies [49].…”

Effects of Ecological Gradients on Tropical Avian Hemoparasites

“…This implies an oceanic influence on the south of the continent that tends to ameliorate the climate favoring the existence and development of vectors and the possibility of diseases transmission, even at high latitudes (Merino et al 2008). Finally, islands also have a clear effect of oceans on their climate, but usually infections are less frequent due to the lack of appropriate vectors (Scheuerlein and Ricklefs 2004;Barrientos et al 2014;Gangoso et al 2019). However, the naïve native avifauna on islands could be severely affected when a new parasite is introduced (van Riper 1991; Parker 2018; see Chap.…”

Where are we in the host-parasite relationships of native land vertebrates in Macaronesia?

“…Sin embargo, lo que no es tan fácil de explicar es el porqué de estos niveles de prevalencia tan bajos encontrados en La Palma, donde sí hay haemosporidios aviares (Illera et al 2017b), así como los potenciales vectores (Illera et al 2015). A día de hoy carecemos de información precisa de los factores que explicarían con certeza este resultado, pero quizás pudiera deberse a algún tipo de incompatibilidad o especificidad entre los parásitos y sus hospedadores invertebrados (dípteros), a una baja abundancia de potenciales vectores, o a una ausencia de especificidad entre los dípteros y sus presas las aves (Martínez-de la Puente et al 2011;Ferraguti et al 2018;Gangoso et al 2019;Gutiérrez-López et al 2020). De hecho, un resultado llamativo es que las prevalencias de haemosporidios del género Haemoproteus en aves sedentarias no migradoras fue-4 Illera y Perera 2020 Ecosistemas 29(2): 1971 Figura 2.…”