Evidence of much wider distribution of the potential West Nile virus vector, Culex modestus, in the UK

Culex modestus is a primary vector of West Nile virus (WNV) in Europe, feeding on both avian and mammalian hosts. Since its rediscovery in the UK in Kent in 2010, its range has been reported throughout the coastal parts of the Thames Estuary, as well as parts of Suffolk and Cambridgeshire. This paper reports further detections of Cx. modestus in the UK in new localities. Surveillance was conducted using Mosquito Magnet and BG-Pro traps baited with synthetic lures between June and October 2024, supplemented by field sampling for immature stages. Populations were detected at two new localities in Cambridgeshire (Ouse Fen, Fowlmere) and on the Sussex/Hampshire border (Pagham Harbour, Farlington Marshes), with high abundances in some localities. The presence of Cx. modestus at new locations suggests ongoing range expansion in the UK. Continued monitoring of this mosquito is important for determining and managing potential WNV transmission risk to public health.