Background: The intensification of trade and travel is linked to the growing number of imported cases of dengue, chikungunya or Zika viruses into continental Europe and to the expansion of invasive mosquito species such as Aedes albopictus and Aedes japonicus. Local outbreaks have already occurred in several European countries. Very little information exists on the vector competence of native mosquitoes for arboviruses. As such, the vectorial status of the nine mosquito species largely established in North-Western Europe (Aedes cinereus and Aedes geminus, Aedes cantans, Aedes punctor, Aedes rusticus, Anopheles claviger s.s., Anopheles plumbeus, Coquillettidia richiardii, Culex pipiens s.l., and Culiseta annulata) remains mostly unknown. Objectives: To review the vector competence of both invasive and native mosquito populations found in North-Western Europe (i.e., France, Belgium, Germany, United Kingdom, Ireland, The Netherlands, Luxembourg and Switzerland) for dengue, chikungunya, Zika, West Nile and Usutu viruses. Methods: A bibliographical search with research strings addressing mosquito vector competence for considered countries was performed. Results: Out of 6357 results, 119 references were related to the vector competence of mosquitoes in Western Europe. Eight species appear to be competent for at least one virus. Conclusions: Aedes albopictus is responsible for the current outbreaks. The spread of Aedes albopictus and Aedes japonicus increases the risk of the autochthonous transmission of these viruses. Although native species could contribute to their transmission, more studies are still needed to assess that risk.

Background: In the context of the increasing circulation of arboviruses, a simple, fast and reliable identification method for mosquitoes is needed. Geometric morphometrics have proven useful for mosquito classification and have been used around the world on known vectors such as Aedes albopictus. Morphometrics applied on French indigenous mosquitoes would prove useful in the case of autochthonous outbreaks of arboviral diseases. Methods: We applied geometric morphometric analysis on six indigenous and invasive species of the Aedes genus in order to evaluate its efficiency for mosquito classification. Results: Six species of Aedes mosquitoes (Ae. albopictus, Ae. cantans, Ae. cinereus, Ae. sticticus, Ae. japonicus and Ae. rusticus) were successfully differentiated with Canonical Variate Analysis of the Procrustes dataset of superimposed coordinates of 18 wing landmarks. Conclusions: Geometric morphometrics are effective tools for the rapid, inexpensive and reliable classification of at least six species of the Aedes genus in France.

Mermithid nematodes (Nematoda, Mermithidae) parasitising mosquitoes could be useful as biological agents for the control of host populations. Nine female mosquitoes belonging to the species Aedes cantans, Ae. communis, and Ae. rusticus were found parasitised by mermithids in Northern France. Sequencing of partial 18S rDNA showed 100% sequence homology for all processed specimens. The mermithid sequences were closely related to specimens previously recorded from Anopheles gambiae in Senegal. However, 18S sequences do not allow for identification of nematodes at the genus or species level. Our specimens could also be related to Strelkovimermis spiculatus, or belong to other genera not yet sequenced such as Empidomermis, the only mermithid genus recorded from mosquitoes in France.

Depuis les années 1960, la France métropolitaine a subi des émergences et des réémergences des virus Usutu (USUV) et West-Nile (WNV). Ces arbovirus (Arthropod Borne viruses) ont pour réservoir les populations aviaires et sont transmises par un moustique vecteur du genre Culex. En France, le WNV a connu plusieurs émergences dont la fréquence s’accélère depuis les années 2000. A ce jour, la circulation de ce virus est limitée au sud de la France, s’étendant depuis son foyer historique situé dans la région de la Camargue. Régulièrement, des cas humains sont détecté. Son vecteur Culex pipiens est ubiquitaire sur le territoire. Le virus Usutu a quant à lui émergé en France métropolitaine en 2015, causant des épisodes de mortalité aviaires chez des espèces sensibles telles que le merle (Turdus merula) ou encore la chouette lapone (Strix nebulosa). Usutu s’est rapidement disséminé sur le territoire métropolitain, touchant des populations aviaires résidentes de la région Grand-Est. Dans ce contexte, nous avons poursuivi des travaux d’inventaires des moustiques de la région pour actualiser les données de présence. Dans un premier temps nous avons voulu apporter notre contribution à l’identification des espèces autochtones par une approche dite de géomorphométrie alaire (Wing Geometric Morphometrics ou WGM), technique qui s’est avérée fiable dans notre contexte régional. Nous avons revu l’ensemble des infections expérimentales réalisées sur des populations de moustiques originaires d’Europe de l’Ouest. Dans cette optique, nous avons testé la compétence vectorielle de trois espèces de moustiques endémiques dans la région Grand-Est pour WNV et USUV (Aedes rusticus, Anopheles plumbeus et Culex pipiens). Les données acquises par ces expérimentations pourront permettre à l’avenir une meilleure préparation et une meilleure prise en charge d’une hypothétique émergence de WNV ou d’USUV dans la région Grand-Est.

Emerging arboviruses of Orthoflavivirus genus such as West Nile virus (WNV) and Usutu virus (USUV), primarily transmitted by Culex mosquitoes, pose significant public health threats due to their ability to cause severe neurological diseases in humans and animals. While studies in North America and Central Europe have shown that these viruses can persist in overwintering mosquitoes, their role in viral maintenance during the cold season in northeastern France remains unknown. This study aimed to assess whether overwintering female mosquitoes in this region could harbor WNV or USUV during the cold season, potentially maintaining viral circulation until the following transmission season. Between October 2021 and February 2024, a total of 10,617 overwintering female mosquitoes were collected in various types of habitats, across five departments in northeastern France. The most common species was Culex pipiens (88%). Mosquitoes were grouped into 1,121 pools (1–10 individuals each) and tested by real-time RT-PCR for WNV, USUV, and other flaviviruses using a pan-Flavivirus NS5-targeting assay. All pools tested negative, indicating no evidence of viral RNA in overwintering females. These results suggest that overwintering female mosquitoes in northeastern France do not act as reservoirs for WNV or USUV, and do not contribute to their overwintering maintenance.

Emerging arboviruses of the Orthoflavivirus genus such as West Nile virus (WNV) and Usutu virus (USUV), primarily transmitted by Culex mosquitoes, pose significant public health threats due to their ability to cause severe neurological diseases in humans and animals. While studies in North America and Central Europe have shown that these viruses can persist in overwintering mosquitoes, their role in viral maintenance during the cold season in northeastern France remains unknown. This study aimed to assess whether overwintering female mosquitoes in this region could harbor WNV or USUV during the cold season, potentially maintaining viral circulation until the following transmission season. Between October 2021 and February 2024, a total of 10,617 overwintering female mosquitoes were collected in various types of habitats across five departments in northeastern France. The most common species was Culex pipiens (88%). Mosquitoes were grouped into 1121 pools (1–10 individuals each) and tested by real-time RT-PCR for WNV, USUV, and other flaviviruses using a pan-Flavivirus NS5-targeting assay. All pools tested negative, indicating no evidence of viral RNA in overwintering females. These results suggested that overwintering female mosquitoes in northeastern France do not act as reservoirs for WNV or USUV, and do not contribute to their overwintering maintenance.