Frequency of Culex pipiens complex members in continental Croatia

Members of the Culex pipiens complex are considered a potential vector in the Republic of Croatia, which is why it is extremely important to have data on its distribution as well as data on the species and biotypes found within the Complex. This study was conducted with the aim of determining the frequency of biotypes within the Culex pipiens complex, and especially Culex pipiens/molestus hybrids. Culex pipiens biotype pipiens and Culex pipiens biotype molestus differ in behavior and physiology. Cx. pipiens biotype pipiens mainly feed on the blood of birds, while Cx. pipiens biotype molestus feeds on the blood of mammals. By feeding on both hosts, hybrids can significantly increase the possibility of transmission of various disease agents. The study was conducted in June 2022. Individuals were sampled using a net with a diameter of 25 cm in water habitats and using plastic containers on small and shallow water surfaces. As a diagnostic marker for discrimination among species and biotypes within the Cx. pipiens complex, the nuclear ACE2 and CQ11 microsatellite loci were used. Three representatives of the Complex were confirmed: Culex torrentium, Cx. pipiens biotype pipiens and Cx. pipiens biotype molestus. The most common taxon in the research area was Cx. pipiens biotype pipiens (62% in urban and 69% in rural areas). Cx. torrentium was recorded in the rural area of north-western Croatia only. Cx. pipiens biotype molestus was recorded in south-eastern part of continental Croatia only (8.33%), with greater dominance in urban areas. Cx. pipiens/molestus hybrid was recorded in rural areas of the south-eastern part of continental Croatia (8.33%). This research with its results represents a platform for future research of the Cx. pipiens complex in Croatia.