Identification of a new vector species of avian haemoproteids, with a description of methodology for the determination of natural vectors of haemosporidian parasites

Abstract

Background Haemosporidian parasites are transmitted by dipteran blood-sucking insects but certain vectors remain unidentified for the great majority of described species. Sensitive PCR-based methods are often used for the detection of haemosporidian infection in wild-caught insects. However, this approach alone cannot distinguish between different sporogonic stages and thus is insufficient to demonstrate that the parasites produce the infective stage (sporozoite), which is essential for transmission. To prove that PCR-positive insects could act as vectors, the record of sporozoites is needed. We developed a methodology for the determination of natural vectors of avian Haemoproteus species and other haemosporidians. The essence of this approach is to apply PCR-based and microscopic diagnostic tools in parallel for sporozoite detection in insects. Methods Culicoides biting midges transmit avian Haemoproteus parasites, but certain insect species, which are involved in transmission, remain insufficiently investigated. Biting midges were collected in the wild and identified; parous females were dissected and preparations of thorax content containing salivary glands were prepared. Remnants of the dissected midges were screened using PCR-based methods. Only thorax preparations of PCR-positive biting midges were examined microscopically. Results In total, 460 parous females belonging to 15 species were collected and dissected. DNA of haemosporidians was detected in 32 (7%) of dissected insects belonging to 7 species. Of the thorax samples PCR-positive for Haemoproteus parasites, two preparations were microscopically positive for sporozoites. Both biting midges were Culicoides kibunensis. Haemoproteus pallidus (hPFC1) was identified, indicating that transmission of this infection occurs at the study site. It was proved that seven species of biting midges take bird blood meals naturally in the wild. Conclusions Culicoides kibunensis is a new vector species of avian haemoproteids and is a natural vector of H. pallidus . Numerous studies have identified vectors of Haemoproteus parasites experimentally; however, this is the first direct identification of a natural vector of Haemoproteus infection in the Old World. We suggest using the described methodology for vector research of Haemoproteus and other haemosporidians in the wild. Electronic supplementary material The online version of this article (10.1186/s13071-019-3559-8) contains supplementary material, which is available to authorized users.

The use of nest boxes in determination of biting midges involved in transmission of Haemoproteus parasites

“…We have found H. majoris (hCWT4) in C. segnis biting midges during this study. Haemoproteus majoris (hWW2) DNA was also recently found in C. punctatus in Lithuania [8], so biting midges of these two species can be considered as possible vectors of H. majoris. Culicoides impunctatus is known to be one of the natural vectors of H. majoris (hPARUS1) [10].…”

“…Culicoides kibunensis was detected as a vector of Haemoproteus pallidus in Lithuania, because two wild caught individuals of this species were detected to harbor DNA as well as sporozoites of H. pallidus (lineage hPCF1) [8]. Culicoides nubeculosus is the only Palearctic Culicoides species cultivated in laboratory, that is why, experimental studies on sporogony of several Haemoproteus spp.…”

“…Culicoides circumscriptus, C. festivipennis [8,15,45], C. kibunensis [8,16,17], C. pictipennis [8,17,45], C. segnis [16], C. scoticus [8,17], C. punctatus and C. obsoletus [8].We have detected avian haemosporidian parasites in biting midges belonging to 5 Culicoides species and have added C. reconditus to this list ( Table 1). Culicoides punctatus and C. pictipennis females were found in nest boxes and were infected with H. minutus (hTURDUS2 and hTUPHI01, respectively) ( Table 1).…”

“…They are vectors of the Haemoproteus (Haemosporida) parasites, which can cause diseases and even lethal pathology in non-adapted birds [1][2][3][4][5]. At present there are 1368 species of biting midges known in the world [6], but only 12 of them have been proved to support complete sporogony of avian Haemoproteus parasites [7,8], though about 150 species of Haemoproteus have been described [9].…”

Significant reduction in abundance of peridomestic mosquitoes (Culicidae) and Culicoides midges (Ceratopogonidae) after insecticide intervention in western São Paulo, Brazil

“…As part of that study, we investigated for the rst time the impact of these two insecticide-based interventions [sprayed residual insecticide and insecticide-impregnated dog collars] on two biting Diptera groups: mosquitoes and Culicoides biting midges, which are pests often found in abundance in chicken sheds, other animal shelters, and inside human dwellings throughout Brazil [1,3,7,8,9,12] along with Lu. longipalpis sand ies.…”