While mosquito invasions and associated pathogens are increasingly prominent in Europe, evidence gaps remain for many northerly regions where proactive management interventions may be most effective. At the regional periphery of Europe, there remains a significant knowledge gap concerning mosquito vector distributions in Northern Ireland. This study aimed to address this major gap by systematically surveying larval and adult mosquito populations in key habitats (ponds, reedbeds, saltmarsh, wet grasslands, wet woodlands, and urban gardens). We further identified environmental drivers of important vector species abundance and screened collected specimens with molecular techniques to identify presence of cryptic human-biting vector species. In Northern Ireland, mosquitoes (including potential bridge vectors of West Nile and Usutu viruses) were found to be widely distributed. Between May and August 2025, a total of 2430 mosquitoes (951 adults and 1479 larvae) were collected over 196 trap nights and 76 larval collections. Collections encompassed 17 species, with Culex pipiens/torrentium being the most widely distributed and abundant taxon recorded. Mosquito abundances were greatest in reedbed habitats, related negatively with rainfall and peaked in June and July. A subset of Culex pipiens/torrentium mosquitoes were identified to species/biotype level using PCR, with the majority (89.3%) identified as Culex pipiens pipiens and 9.3% as Culex torrentium. Importantly, the first detections of Culex pipiens/molestus hybrids (1.8%) on the island of Ireland were found. This work underscores the wide, yet previously undocumented abundance and distribution of potential zoonotic vectors in Northern Ireland and provides an important baseline for management planning and future research, while contributing to broader understandings of environmental population drivers and distributions.

While mosquito invasions and associated pathogens are increasingly prominent in Europe, evidence gaps remain for many northerly regions where proactive management interventions may be most effective. At the regional periphery of Europe, there remains a significant knowledge gap concerning mosquito vector distributions in Northern Ireland. This study aimed to address this major gap by systematically surveying larval and adult mosquito populations in key habitats (ponds, reedbeds, saltmarsh, wet grasslands, wet woodlands, and urban gardens). We further identified environmental drivers of important vector species abundance and screened collected specimens with molecular techniques to identify presence of cryptic human-biting vector species. In Northern Ireland, mosquitoes (including potential bridge vectors of West Nile and Usutu viruses) were found to be widely distributed. Between May and August 2025, a total of 2430 mosquitoes (951 adults and 1479 larvae) were collected over 196 trap nights and 76 larval collections. Collections encompassed 17 species, with Culex pipiens/torrentium being the most widely distributed and abundant taxon recorded. Mosquito abundances were greatest in reedbed habitats, related negatively with rainfall and peaked in June and July. A subset of Culex pipiens/torrentium mosquitoes were identified to species/biotype level using PCR, with the majority (89.3%) identified as Culex pipiens pipiens and 9.3% as Culex torrentium. Importantly, the first detections of Culex pipiens/molestus hybrids (1.8%) on the island of Ireland were found. This work underscores the wide, yet previously undocumented abundance and distribution of potential zoonotic vectors in Northern Ireland and provides an important baseline for management planning and future research, while contributing to broader understandings of environmental population drivers and distributions.

Les températures élevées de l’été et le retour de quelques orages stimulent cet agent infectieux transmis des oiseaux aux humains par les moustiques communs.   Par Delphine Roucaute Publié hier à 18h00, modifié à 05h54   "... Ce virus, transmis par les Culex pipiens, les moustiques communs reconnaissables à leur bruit strident au cœur de la nuit, et non pas par les moustiques tigres, est à l’origine de 145 cas humains depuis la fin juin, selon le bulletin de Santé publique France publié le 30 septembre. Un chiffre inédit, puisque, depuis sa première apparition en France dans les années 1960, le virus n’était jusque-là à l’origine que de quelques dizaines de cas par an." (...)

In Germany, insecticide use is recommended during mosquito-borne disease outbreaks, yet nationwide data on insecticide resistance in key vector species are scarce. This is particularly relevant for Culex pipiens s.l., a vector of West Nile virus. Here, we provide the first broad-scale assessment of molecular insecticide resistance (kdr and ace-1 mutations) in Cx. pipiens f. pipiens across Germany. We associated insecticide resistances with environmental conditions, potential links with mitochondrial variation of the cytochrome c oxidase I (COI) gene as well as phenotypic resistance (CDC bottle assay with permethrin) of the Frankfurt population with elevated kdr frequencies. Kdr resistance alleles were detected in German Cx. pipiens f. pipiens reaching frequencies of up to 50% in the metropolitan areas of Berlin and Frankfurt am Main. Annual precipitation was negatively associated with kdr allele frequency. Interestingly, ace-1 resistance mutations were only present in the metropolitan area of Frankfurt am Main and in Muggensturm (Rhine valley, southwestern Germany). COI haplotype analyses revealed low genetic variability within German Cx. pipiens f. pipiens populations with no association to the insecticide resistance genotype. Phenotypic assays of the Frankfurt population showed early signs of permethrin resistance, but unmatched genotypic and phenotypic resistance state. This study provides the first broad-scale assessment of molecular insecticide resistance in Cx. pipiens f. pipiens across Germany, establishing a baseline for resistance surveillance and vector control. Further research is needed to identify factors shaping phenotypic resistance, as molecular markers alone may not reliably predict resistance. Since sampling was restricted to urban green spaces, broader sampling across environmental gradients is needed to identify additional environmental effectors.

In Germany, insecticide use is recommended during mosquito-borne disease outbreaks, yet nationwide data on insecticide resistance in key vector species are scarce. This is particularly relevant for Culex pipiens s.l., a vector of West Nile virus. Here, we provide the first broad-scale assessment of molecular insecticide resistance (kdr and ace-1 mutations) in Cx. pipiens f. pipiens across Germany. We associated insecticide resistances with environmental conditions, potential links with mitochondrial variation of the cytochrome c oxidase I (COI) gene as well as phenotypic resistance (CDC bottle assay with permethrin) of the Frankfurt population with elevated kdr frequencies. Kdr resistance alleles were detected in German Cx. pipiens f. pipiens reaching frequencies of up to 50% in the metropolitan areas of Berlin and Frankfurt am Main. Annual precipitation was negatively associated with kdr allele frequency. Interestingly, ace-1 resistance mutations were only present in the metropolitan area of Frankfurt am Main and in Muggensturm (Rhine valley, southwestern Germany). COI haplotype analyses revealed low genetic variability within German Cx. pipiens f. pipiens populations with no association to the insecticide resistance genotype. Phenotypic assays of the Frankfurt population showed early signs of permethrin resistance, but unmatched genotypic and phenotypic resistance state. This study provides the first broad-scale assessment of molecular insecticide resistance in Cx. pipiens f. pipiens across Germany, establishing a baseline for resistance surveillance and vector control. Further research is needed to identify factors shaping phenotypic resistance, as molecular markers alone may not reliably predict resistance. Since sampling was restricted to urban green spaces, broader sampling across environmental gradients is needed to identify additional environmental effectors.

¡Buenas a tod@s! Hacía mil que no me pasaba por aquí (oposiciones, mucho trabajo...), pero hoy he decidido revivir un poco la cuenta con este precioso ejemplar de Syritta pipiens, una mosca florícola…

Hola a tothom! Feia molt de temps que no passava per aquí (opos, molta feina...), però avui us vull regalar aquesta foto que vaig fer d'un exemplar de Syritta pipiens, una mosca de les flors de la…

Author summary West Nile virus and Usutu virus are two closely related flaviviruses transmitted by mosquitoes. Both viruses share a very similar transmission cycle and often occur in the same regions....

by Christin Körsten, Cornelia Silaghi, Mandy Schäfer The epidemiological co-circulation of the two flaviviruses West Nile virus (WNV) and Usutu virus (USUV) in several European countries poses the risk of co-infections in vertebrate hosts and mosquito vectors. WNV is an important human pathogen, whereas USUV is primarily relevant in veterinary and wildlife health. Co-infections have been detected in birds and, occasionally, in humans. To determine the potential consequences of co-exposure and co-infections in mosquitoes on viral transmission, lab-reared Culex pipiens biotype molestus were orally infected with both viruses either simultaneously or sequentially at 7-day intervals with German isolates of WNV lineage 2 and USUV lineage Europe 3. Simultaneous exposure resulted in a significantly increased WNV infection rate, while infection and transmission of USUV were inhibited at the same time. During sequential exposure, prior WNV exposure also had a negative effect on susceptibility to USUV, whereas conversely, WNV infection rates were not altered by prior USUV exposure. Furthermore, mosquitoes with established co-infections after simultaneous co-exposure exhibited higher WNV viral loads than those infected exclusively with WNV. The study reveals complex interactions between WNV, USUV, and the mosquito vector, which could influence vector competence and vector capacity of Culex pipiens biotype molestus in areas with co-circulation of WNV and USUV.