Biting midges (Culicoides, Diptera) transmit Haemoproteus parasites of owls: evidence from sporogony and molecular phylogeny

Abstract

BackgroundHaemoproteus parasites are widespread, and several species cause diseases both in birds and blood-sucking insects. These pathogens are transmitted by dipterans belonging to the Ceratopogonidae and Hippoboscidae, however certain vector species remain unknown for the majority of Haemoproteus spp. Owls are often infected by Haemoproteus parasites, but experimental studies on vectors of these infections are lacking. The aim of this study was to investigate sporogonic development of two widespread Haemoproteus parasites of owls, H. noctuae and H. syrnii in experimentally infected biting midges Culicoides impunctatus and Culicoides nubeculosus. We also followed in vitro sporogonic development of these infections and determined their phylogenetic relationships with Haemoproteus spp., for which vectors have been identified.MethodsWild-caught C. impunctatus and laboratory reared C. nubeculosus were infected experimentally by allowing them to take blood meals on one individual long-eared owl (Asio otus) and one tawny owl (Strix aluco) harbouring mature gametocytes of H. noctuae (lineage hCIRCUM01) and H. syrnii (hCULCIB01), respectively. The engorged insects were maintained in the laboratory at 16–18 °C, and dissected at intervals in order to follow the development of ookinetes, oocysts and sporozoites. We also observed in vitro development of sexual stages of both parasites by exposure of infected blood to air. The parasite lineages were determined by polymerase chain reaction-based methods. Bayesian phylogeny was constructed in order to determine the relationships of owl parasites with other avian Haemoproteus spp., for which vectors have been identified.ResultsBoth H. noctuae and H. syrnii completed sporogony in C. nubeculosus, and H. noctuae completed sporogony in C. impunctatus. Ookinetes, oocysts and sporozoites of these parasites were reported and described. Gametes and ookinetes of both species readily developed in vitro. In accordance with sporogony data, the phylogenetic analysis placed both parasite lineages in a clade of Culicoides spp.-transmitted avian Haemoproteus (Parahaemoproteus) spp.ConclusionsCulicoides nubeculosus and C. impunctatus are vectors of H. noctuae and H. syrnii. Phylogenies based on cytochrome b gene indicate parasite-vector relationships, and we recommend using them in predicting possible parasite-vector relationships and planning research on avian Haemoproteus spp. vectors in wildlife.

The widespread biting midge Culicoides impunctatus (Ceratopogonidae) is susceptible to infection with numerous Haemoproteus (Haemoproteidae) species

“…motacillae hYWT1 Motacilla flava 1–1.5 3–4 5–8 This study H . noctuae hCIRCUM01 Asio otus 12 d – 7–9 [ 15 ] H . pallidus hPFC1 Ficedula hypoleuca 4–12 d 1.5–2.5 6.5–7.5 This study H .…”

“…Culicoides impunctatus is common in Europe and is abundant at our study site [ 33 , 41 , 42 , 55 ]. Culicoides impunctatus was often considered as mainly a mammalophilic species [ 56 ], but it willingly takes blood meal on birds [ 14 , 15 , 35 , 41 , 42 ]. According to former studies (Table 2 ), C. impunctatus is a competent vector of Haemoproteus lanii , Haemoproteus fringillae , H .…”

“…However, this methodology does not distinguish invasive (sporozoites) and non-invasive (blood forms, ookinetes and oocysts) stages, and thus cannot provide conclusive evidence regarding whether the PCR-positive insects can act as vectors. In other words, the results of solely molecular diagnostics indicate only the possibility as natural vectors [ 8 , 12 – 15 ]. Many recent studies used solely PCR-based tools in vector studies of Haemoproteus [ 9 , 16 , 17 ] and Plasmodium [ 10 , 13 , 18 , 19 ] parasites in wild-caught blood-sucking dipteran insects.…”

“…Recently, a simple methodology of experimental infection of wild-caught Culicoides biting midges with Haemoproteus parasites was developed [ 1 ], and the sporogony of nine Haemoproteus species was investigated in Culicoides impunctatus biting midges [ 14 , 15 , 27 , 33 ]. We predicted that many other common avian haemoproteids can be transmitted by this insect.…”

Haemoproteus paraortalidum n. sp. in captive Black-fronted Piping-guans Aburria jacutinga (Galliformes, Cracidae): high prevalence in a population reintroduced into the wild

“…also occur in the reintroduction area. SameHaemoproteus lineages can be transmitted by different species of biting midges(Atkinson, 1991;Bukauskaitė et al, 2015; Žiegytė et al, 2017), increasing the likelihood of H. paraortalidum n. sp. being transmitted in the reintroduction area.…”