Aedes koreicus (Edwards) (Diptera: Culicidae) is an invasive mosquito species and potential vector of pathogens which has recently colonised a large part of northeastern Italy and other European countries. Several species of cyclopoid copepods are natural predators of mosquito larvae and can be useful biological control agents in artificial containers used as breeding sites by Aedes mosquitoes. However, to ensure behavioural efficiency of these agents, and to avoid the introduction of non-native species, predatory copepods should be selected from the local fauna. In this study, we evaluated the predation efficiency under laboratory conditions of two locally bred populations of cyclopoid copepod species, Macrocyclops albidus (Jurine, 1820) and Mesocyclops leuckarti (Claus, 1857) (Copepoda: Cyclopoida), which are two of the most common European species of cyclopoid copepods, against Ae. koreicus larvae. Predation experiments were also conducted with Aedes (Stegomyia) albopictus (Skuse) as a "reference". In each predation test, one adult female copepod was placed with 50 first instar larvae of a single mosquito species in a Petri dish filled with 10 mL of water. After 24 hours, the mean number (± standard error) of first instar larvae killed by one M. albidus female was 18.6 ± 1.3 Ae. koreicus and 20.9 ± 1.3 Ae. albopictus, and the mean number killed by one M. leuckarti female was 25.8 ± 2.8 Ae. koreicus and 36.1 ± 4.2 Ae. albopictus. In addition, M. leuckarti was slighly less effective against Ae. koreicus than against Ae. albopictus after 48 hours, probably because first instar larvae of Ae. koreicus were larger than first instar larvae of Ae. albopictus. Our findings indicate for the first time that copepods are effective predators of first instar larvae of Ae. koreicus.

This article reports data on the occurrence and spread of three invasive mosquito species: Aedes japonicus, Aedes koreicus, and Aedes albopictus in two regions of Northeast Italy; resulting from larval and adult collections performed during the 2011–2020 period in the framework of different projects. Routine species identification was performed using morphological characters and complemented by molecular methods when required. For the years 2019 and 2020, detailed data are reported which update previous information on municipalities and sites where these species have been detected. Geo-referenced information on the presence of invasive mosquitoes is reported and demonstrated on maps. Additional data on the nature of breeding sites and the finding of native mosquito species in the same collections are also provided.

Background Japanese encephalitis virus (JEV) is the principal cause of mosquito-borne encephalitis in human populations within Asia. If introduced into new geographic areas, it could have further implications for public and animal health. However, potential mosquito vectors for virus transmission have not been fully investigated. The Asian tiger mosquito, Aedes albopictus, has emerged in Europe and is now expanding its geographical range into more northerly latitudes. Culex quinquefasciatus, although absent from Europe, has been detected in Turkey, a country with territory in Europe, and could act as a vector for JEV in other regions. To assess the risk of these invasive species acting as vectors for JEV and therefore potentially contributing to its geographical expansion, we have investigated the vector competence of Ae. albopictus and Cx. quinquefasciatus. Methods Two colonised lines of Ae. albopictus (Italy and Spain) and a line of Cx. quinquefasciatus (Tanzania) were compared for susceptibility to infection by oral feeding with JEV strain SA-14, genotype III at 106 PFU/ml and maintained at 25 °C. Specimens were processed at 7 and 14 days post-inoculation (dpi). Rates of infection, dissemination and transmission were assessed through detection of viral RNA by real-time polymerase chain reaction (RT-PCR) in mosquito body, legs and saliva, respectively, at each time point. Where possible, infection and dissemination were confirmed by immunohistochemical (IHC) detection of the JEV envelope protein. Results Aedes albopictus from Italy showed no susceptibility to infection with JEV strain SA-14. Conversely, Ae. albopictus colonised in Spain was susceptible and 100% of infected mosquitoes that were subjected to saliva screening expressed viral RNA at 14 dpi. Culex quinquefasciatus was highly susceptible to infection as early as 7 dpi and 50% of infected mosquitoes that were subjected to saliva screening expressed viral RNA at 14 dpi. Infection and dissemination were confirmed in Cx. quinquefasciatus by IHC detection of JEV envelope protein in both the mid-gut and salivary glands. Conclusions Aedes albopictus from two different locations in Europe range from being susceptible to JEV and capable of transmission through to being resistant. Culex quinquefasciatus also appears highly susceptible; therefore, both species could potentially act as vectors for JEV and facilitate the emergence of JEV into new regions. Graphical Abstract