Relative abundance and geographical variation of Culex pipiens and Culex torrentium (Diptera: Culicidae) in CO₂ -baited traps in Denmark

European Culex pipiens and Culex torrentium are morphological fairly similar mosquito species with potentially different vector competences for pathogenic viruses. The relative abundance of the two species is therefore important for quantifying the potential for disease transmission in Denmark. Mosquitoes were sampled from 74 different sites in Denmark with CO2 and octenol-baited suction traps. Atotal of 285Culex specimens were identified to species using a restriction enzyme assay. Culex pipiens was the dominating species with 220 (77%) specimens caught at 22 different sites, while 65 (23%) specimens were identified asC. torrentium and only caught at 4 sites. The ratio of the two species differed significantly between sites withC. torrentium dominating in just a single location. Both mosquito species were predominantly caught late in the Danish mosquito season, from mid-August and onwards.