The Study of Biting Midges Culicoides Latreille, 1809 (Diptera: Ceratopogonidae) and the Prevalence of Haemoproteus Kruse, 1890 (Haemosporida: Haemoproteidae) on the Curonian Spit of the Baltic Sea

The part of the life cycle concerning the vectors of avian haemosporidians of the genus Haemoproteus remains only partially studied. This work presents the results of capturing and analyzing female Culicoides biting midges for Haemoproteus infection, collected on the Curonian Spit of the Baltic Sea. The midges were collected from April to August 2023 in dry and wet habitats of the Spit using light traps. Each parous female midge was identified to the species level and then its salivary glands were isolated to prepare a thin smear. The preparation was examined under a light microscope for the presence of parasite stages infecting the birds (sporozoites). PCR analysis was also conducted to assess the prevalence of infection in the midges and the genetic diversity of Haemoproteus spp. among vectors on the Curonian Spit. As a result, 995 Culicoides females belonging to 12 species were collected over the course of 4 months. The highest number of midges was recorded in June. The dominant species were Culicoides kibunensis and Culicoides pictipennis. Molecular analysis showed that 2.71% (n = 27) of the examined individuals contained DNA of Haemoproteus spp. Parasites were found in midges of C. pictipennis, C. kibunensis, C. segnis, C. obsoletus, C. punctatus, C. reconditus, C. festivipennis, and C. pallidicornis from May 15 to July 13. The DNA of the identified parasites belonged to six genetic lineages of Haemoproteus—Haemoproteus parabelopolskyi hSYAT02, H. asymmetricus hTUPHI01, H. minutus hTURDUS2, H. spp. hBRAM1, hHAWF6, and hHIICT1. Sporozoites of H. parabelopolskyi hSYAT02 were detected in two individuals of C. pictipennis and one of C. kibunensis. Thus, taking into account the previous results of other studies, we have assumed that these two midge species are competent vectors for Haemoproteus parasites on the Curonian Spit.