First Nationwide Surveillance of <i>Culex pipiens</i> Complex and <i>Culex torrentium</i> Mosquitoes Demonstrated the Presence of <i>Culex pipiens</i> Biotype <i>pipiens</i>/<i>molestus</i> Hybrids in Germany

<div><p>Mosquitoes and other arthropods may transmit medically important pathogens, in particular viruses such as West Nile virus. The presence of suitable hosts and competent vectors for those zoonotic viruses is essential for an enzootic transmission, which is a prerequisite for epidemics. To establish reliable risk projections, it is an urgent need for an exact identification of mosquito species, which is especially challenging in the case of sibling species, such as <i>Culex. pipiens pipiens</i> biotypes <i>pipiens</i> and <i>molestus</i>. To facilitate detection of different <i>Culex pipiens</i> forms and their hybrids we established a multiplex real-time PCR. <i>Culex pipiens</i> samples were obtained by egg raft collection and rearing until imago stage or adult sampling using CO₂ baited traps and gravid traps. In total, we tested more than 16,500 samples collected all over Germany in the years 2011 and 2012. The predominant species in Germany are <i>Culex pipiens pipiens</i> biotype <i>pipiens</i> and <i>Culex. torrentium</i>, but we also detected <i>Culex pipiens pipiens</i> biotype <i>molestus</i> and hybrids of the two <i>pipiens</i> biotypes at sites where both species occur sympatrically. This report of a potentially important bridge vector for West Nile virus might have major impact in the risk projections for West Nile virus in Germany.</p>