High Abundance of Haemoproteus Parasites in Culicoides (Diptera, Ceratopogonidae), with a Confirmation of Culicoides reconditus as a New Vector of These Avian Blood Parasites

Simple Summary Haemoproteus parasites are one of the most studied avian blood parasites; however, their natural vectors, Culicoides biting midges, have been identified for only a small portion of them. The main reason for that might be due to the existence of a few research groups working with an integrative approach that allows not only the identification of parasite DNA in the insects, but also confirms the presence of the parasite infective stage (sporozoites) using microscopy. In this study, we aimed to identify the natural vectors of Haemoproteus parasites and to determine their prevalence in Culicoides biting midges in four different localities in Lithuania. Almost 2000 parous Culicoides females belonging to 11 species previously registered in the country were processed. The most abundant one was C. pictipennis. Parasite DNA was found in 7.9% of the analyzed biting midges, and sporozoites were present in almost 30% of these insects. The Botanical Garden was the locality with the highest abundance of biting midges and parasite species, as well as the place with the highest number of biting midges containing sporozoites. One new Haemoproteus vector (C. reconditus) was confirmed, and 12 new interactions between Haemoproteus parasite lineages and Culicoides biting midges of different species were identified. This study helps to understand the relationship between Haemoproteus parasites and Culicoides biting midges in the wild. Abstract Haemoproteus parasites are the most diverse among Haemosporida. However, their natural vectors (Culicoides) are still poorly investigated and were identified for only a few parasite species and lineages. The application of an integrative approach (insect dissection, microscopic analysis, and molecular-based methods) is necessary in these studies, which have been carried out by a few research groups, mainly in Europe. The aim of this study was (i) to determine the Culicoides species that are naturally infected by Haemoproteus parasites, and which can support its complete sporogonic development, and (ii) to investigate the prevalence of Culicoides species and Haemoproteus parasite lineages in different study sites. In total, 1953 parous Culicoides females, from 11 species, were collected in four different localities in Lithuania and were dissected and analyzed using an integrative approach. The most abundant was C. pictipennis (30.3%). Parasite DNA was found in 7.9% of all investigated Culicoides, of which ~30% had sporozoites in their salivary glands, confirming their vector competence for these parasites. The Botanical Garden presented the highest number of Culicoides parous females, Culicoides species, and parasite lineages, as well as the highest positivity for sporozoites. Culicoides reconditus was confirmed as a natural vector of Haemoproteus parasites, sporozoites of six Haemoproteus lineages were reported for the first time, and 12 new interactions between Haemoproteus parasite lineages and Culicoides species were identified. Haemoproteus parasites seem to be transmitted by a high number of Culicoides species, with C. kibunensis, C. pictipennis, and C. segnis being the most important vectors.