A survey targeting exotic Aedes mosquito species in Central Europe, summer 2023, reveals the extensive occurrence of Aedes japonicus in Poland

Abstract

In the frame of the entomological VectorNet network and its capacity building activities, we collected original mosquito dis-tribution data in southern Poland and bordering areas of the Czech Republic, Germany and Slovakia, in June and September–November 2023. Because of the suspected occurrence of Aedes japonicus or Ae. koreicus in Poland, provided by a photo postedearly 2022 on iNaturalist, we targeted the exotic Aedes species in our sampling strategy, but also collected data on other mos-quito species. Besides some adult catches, we mainly collected mosquito immature stages from artificial and natural watercontainers but occasionally from other aquatic habitats. In addition, we collated citizen data and modelled the distribution ofAe. japonicus in Europe incorporating the newly collected data. During this snapshot field study, a total of 162 samples, including139 yielding mosquitoes, were taken from 111 locations across 47 administrative units, resulting on the detection of 22 mosquitotaxa. Our study provides the first substantiated records of Ae. japonicus and Anopheles petragnani in Poland (the second con-firmed by molecular identification). While Ae. japonicus is clearly established over a large part of the country, no other exoticmosquito species was detected. The presence of Ae. japonicus was also confirmed at one location by four citizen records submit-ted to MosquitoAlert in 2023. Regarding native mosquitoes, we identified their presence in 127 species/NUTS3 combinations(113 for Poland, including a single record for An. petragnani). An updated modelling of the distribution of Ae. japonicus suggestshigher environment suitability in Central and Eastern Europe than has been previously estimated. Aedes japonicus is probablywidespread in the Czech Republic and Slovakia, and might soon colonise the bordering region of Ukraine. Its establishmentextends the putative mosquito vector list for West Nile and Rift Valley fever viruses in Central Europe.