Climate change is expected to drive the northward expansion of phlebotomine sand flies in Europe, increasing the potential for transmission of vector-borne pathogens such as Leishmania infantum. This study assessed the historical baseline and future climatic suitability for Phlebotomus mascittii, the northernmost distributed sand fly species in Europe, across Western Europe. A mixed-effects logistic regression model was developed using summer climatic variables and land cover data, based on standardised field surveys conducted in 2023-2024 across France, Germany, Luxembourg, Belgium, and the Netherlands. The model was applied to project future suitability under three Shared Socioeconomic Pathways (SSP2-4.5, SSP3-7.0, SSP5-8.5) for the periods 2041-2060 and 2081-2100. Results indicate an increase of 20-30 percentage points in predicted climatic suitability relative to the historical baseline across Luxembourg, Belgium, western Germany, and the southern Netherlands by 2041-2060 under all SSP scenarios. By 2081-2100, this expansion intensifies, reaching projected average increases in climatic suitability across the study area of approximately 28 percentage points under SSP2-4.5, 45 percentage points under SSP3-7.0, and 57 percentage points under SSP5-8.5, with the largest increases occurring in the northernmost regions. The model showed moderate discrimination (AUC = 0.74, 95% CI: 0.68-0.80), with grouped 5-fold cross-validation yielding a mean AUC of 0.71. At the optimal threshold (0.164), apparent sensitivity was 0.55 and specificity 0.83 (accuracy = 0.80; TSS = 0.39). Accordingly, the projections should be interpreted as indicators of areas with increasing climatic suitability rather than precise predictions of future species occurrence, establishment, or pathogen transmission. Overall, the findings suggest that climate change may substantially expand climatically suitable areas for Ph. mascittii in the northern distribution margin in Western Europe, highlighting the need for adaptive surveillance and providing a spatial framework to support targeted vector surveillance and future One Health preparedness.

In the context of climate change and rapid environmental changes in the Mediterranean basin, accurate and up-to-date mosquito distribution data are essential to support the control of mosquito-borne diseases, which remain a major public health concern. Here, we report the results of intermittent, nationwide, cross-sectional mosquito sampling missions conducted in Tunisia between 2013 and 2023 to update the Culicidae checklist and document current species distribution of species. A total of 35 species were collected, compared with 49 species previously reported in the Tunisian literature. The primary malaria vectors Anopheles labranchiae and An. claviger sensu stricto were still recorded in the north, while An. multicolor and An. sergentii were found in the south, indicating that vigilance remains necessary following malaria elimination. The most abundant and widespread species were Aedes caspius, Ae. detritus, Culex perexiguus and Cx. pipiens. The latter two are recognised as vectors of pathogens such as West Nile virus and therefore require sustained surveillance. Several mosquito species previously reported in the literature were not detected during our surveys. The invasive species Ae. Albopictus, recently established in Tunisia, requires particular monitoring due to its spread to several regions of the country.

Native to East Asia, the Asian bush mosquito (Aedes japonicus) has recently expanded its global range, with established invasive populations in Europe and North America. Given its potential role as a vector of various arboviruses, understanding its invasion process and ecological dynamics is crucial for managing its spread and mitigating public health risks. In the Iberian Peninsula, the species was first detected in Asturias in 2018 and has since expanded to neighbouring regions. Here, we elucidate the invasion pathways and possible origins of Ae. japonicus populations in Spain using sequence data and microsatellite markers, and by screening for the presence of maternally transmitted bacteria of the genus Wolbachia. We analysed 635 Ae. japonicus from 14 countries, including Japan (native range), the United States, and 12 European countries. No clear association between haplotypes and geographical location was detected in any of the three genes analysed (nuclear ITS2, mitochondrial COI and ND4). Wolbachia was not detected in any of the screened samples. In contrast, microsatellite-based population structure analyses showed that most Spanish samples clustered closely with those from College Park, Maryland (USA), located near the Port of Baltimore, one of the largest ports in the United States and a recognised gateway for invasive species introductions. Northern Spain hosts major seaports such as Bilbao and Gijón, whereas the nearest established Ae. japonicus population in Europe lies over 1,000 km away in northeastern France. Taken together, these findings suggest that the most plausible invasion route of Ae. japonicus into Spain involves maritime transport from the eastern coast of the United States to northern Spanish ports, likely accompanied by additional minor introductions of European origin. The inclusion of additional microsatellite loci originally developed for Ae. albopictus yielded results consistent with those obtained using Ae. japonicus-specific loci, reinforcing the robustness of the observed patterns. This work provides new insights into the invasion process of Ae. japonicus in Europe and highlights the need for continuous monitoring and tailored interventions at key ports of entry.

Abstract A snapshot field survey was conducted in the Balearic Islands (Spain) to widen knowledge about mosquito species present in the archipelago. A search for mosquito species records in published literature, local mosquito collections and unpublished grey literature was also undertaken. The main mosquito habitats (except urban habitats) on the four major islands of the archipelago (Mallorca, Menorca, Eivissa and Formentera) were visited between October and November 2019. A mosquito survey was conducted in 32 municipalities, including field collection of larvae, pupae and adults. The literature review updated the list of mosquito species in the Balearic Islands to 23 taxa (one invasive species and 22 considered native to the region). The 169 field samples collected during the snapshot identified 19 species, including three first records in the Balearic Islands (Anopheles marteri, Culex mimeticus, and Cx. impudicus), and also confirmed the presence of Aedes detritus, considered extinct until 2020. Seven species reported in the Balearics were not detected, i.e. Ae. aegypti, Ae. rusticus, An. algeriensis, An. atroparvus, An. claviger s.s., Coquillettidia richiardii, and Cx. hortensis. Mosquito larvae were collected from a wide variety of natural and artificial habitats, with torrent bed pools housing the highest diversity (12 species). The most common species across a wide variety of breeding sites were Cx. pipiens followed by Culiseta longiareolata and Cx. laticinctus. Moreover, we provide information about the possible vector role of reported species in the Balearic Islands.

Preventing local transmission of malaria from imported cases is crucial for achieving and maintaining malaria elimination. This study aimed to investigate the epidemiological characteristics of imported malaria cases and assess the distribution of malaria vectors in Qatar. Data from January 2016 to December 2022 on imported malaria, including demographic and epidemiological characteristics, travel-related information, and diagnostic results, were collected and analysed using descriptive statistics. Field surveys conducted in 2021-22 collected mosquitoes using various traps across Qatar. The collected samples underwent morphological and molecular characterization at Qatar University. A total of 2693 cases were reported, with a mean incidence of 13.5/100 000 population, decreasing from 18.8/100 000 in 2016 to 5.5/100 000 in 2020. Most cases were Plasmodium vivax (57.4%) followed by P. falciparum (40.4%). The median age was 32.9 +/- 12.5 years, primarily males (86.7%), expatriates (99.6%) and notified during the hot months (July to September). Cases were mainly imported from the Eastern Mediterranean Region followed by the African and South-East Asia Region with no deaths and indigenous cases. Anopheles stephensi was identified as a widely distributed species, but none carried the Plasmodium pathogen. Despite no reports of local transmission, the presence of An. stephensi and favourable environmental conditions pose a risk in Qatar. Strengthening surveillance for imported malaria and reviewing epidemic protocols are necessary. Conventional field studies are imperative to address knowledge gaps in Anopheles mosquito ecology and biting habits in Qatar, accurately assessing the risk of local malaria transmission to support Qatar's malaria-free status.

Mosquito-associated microbiota are influenced by a number of factors, e.g., geography, host species, and developmental stage. Understanding these microbiotas is crucial for assessing their role as vectors and in pathogen dissemination and most studies have largely focused on a few model species, while others like Aedes japonicus remain poorly characterized. Here, we compared the bacterial communities of Aedes albopictus and Aedes japonicus across eight countries: six in Europe, plus the USA and Japan, from both adults and larval stages when possible, using 16S rRNA amplicon sequencing. We found large differences in microbiota composition between mosquito species, with Ae. albopictus exhibiting lower bacterial diversity than Ae. japonicus . Geographic variation in bacterial diversity was also evident, with mosquitoes from Japan and the Netherlands harbouring the most diverse bacterial communities, while Austrian populations displayed the lowest diversity. Developmental stage (adults and larvae) had the strongest influence on bacterial composition, with aquatic-associated genera such as Limnohabitans and Aeromonas dominating larvae, whereas adult mosquitoes harboured higher abundances of Acinetobacter and Methylobacterium . No association was found between Aedes species genetic distance, determined by relatedness, and the bacterial community compositions. A number of bacterial genera with known pathogenic potential, including Pseudomonas , Serratia , Klebsiella , and Acinetobacter , were detected across multiple locations, suggesting that mosquitoes could serve as environmental reservoirs for opportunistic and antimicrobial-resistant bacteria. We identified Wolbachia in Ae. albopictus from Spain and Italy and at low abundances in Ae. japonicus from the USA and Japan, marking one of the first reports of Wolbachia in this species. This is, to our knowledge, the most comprehensive study on Ae. japonicus microbiotas. Our findings provide insights into the ecological and epidemiological implications of mosquito microbiota and emphasize the need for further investigation into their role in pathogen transmission and antimicrobial resistance dissemination.

Understanding how life is adapting to urban environments represents an important challenge in evolutionary biology. In this work, we investigate a widely cited example of urban adaptation, Culex pipiens form molestus, also known as the London Underground mosquito. Population genomic analysis of ~350 contemporary and historical samples counters the popular hypothesis that molestus originated belowground in London <200 years ago. Instead, we show that molestus first adapted to human environments aboveground in the Mediterranean or Middle East over the course of more than 1000 years, possibly in association with ancient agricultural civilizations of the Middle East. Our results highlight the role of early human society in priming taxa for contemporary urban evolution. They also provide insight into whether and how molestus contributes to West Nile virus transmission in modern cities.

Abstract The distribution and abundance of Phlebotomine sand flies north of the Alps is poorly known. In Belgium, Phlebotomus mascittii was reported only once in the early 2000s from two locations in the southeastern part of the country. During a VectorNet field survey in 2023, no sand flies were detected in the provinces of Liège, Luxembourg, and Namur. As an extension of this investigation, a brief survey was conducted in August 2024 across four localities in the province of Luxembourg, Belgium. Using 16 light trap-nights and one resting catch, a single male specimen of Ph. mascittii was captured in a light trap placed in a stable/house ruin at Beauregard, commune of Rouvroy. This finding confirms the presence of Ph. mascittii in Belgium, 22-23 years after its initial finding. This detection highlights the need for further investigation on sand fly occurrence in Belgium, to determine species diversity, distribution and abundance.

Within the context of VectorNet, the European Centre for Disease Prevention and Control (ECDC) and the European Food Safety Authority (EFSA) publish regularly updated vector distribution maps, which are informed by a comprehensive review of the literature, data from the VectorNet Entomological Network, and relevant reports. This protocol focuses on the systematic collection of data derived from peer-reviewed publications. The primary objective of this living systematic literature review (SLR) is to gather information regarding the presence, abundance, and seasonal patterns of targeted vector species, including mosquitoes, sand flies, biting midges, and ticks, within the geographical scope defined by VectorNet. Studies will be identified through searches in Web of Science™ and Medline/PubMed. Eligible studies will be screened and analysed for methodological rigor and relevance. The review will provide rigorous data that will be integrated in the VectorNet distribution maps.

Rift Valley fever (RVF) is a zoonotic vector-borne disease mainly transmitted by mosquitoes, and present in Africa, the Arabian Peninsula, and the Indian Ocean. The endemic situation in Mauritania, and the recent outbreaks in Libya have raised concerns about the potential spread of the virus in the western Mediterranean Basin, where competent mosquitoes are present. However, given the large diversity of climates and landscapes in this region, the areas and periods at risk of RVF virus (RVFV) transmission remain unknown. Vector abundance is one of the drivers of arboviruses transmission, therefore knowledge on mosquito species distributions and population dynamics is needed to implement surveillance and to assess the risk of RVFV circulation. Here, we adapted a published modelling framework of mosquito population dynamics to five potential RVFV vectors in the western Mediterranean Basin (Aedes caspius, Aedes detritus, Aedes vexans, Culex pipiens and Culex theileri). The mechanistic model was designed with a daily time step and a 0.1 degrees x 0.1 degrees spatial resolution and takes temperature and precipitations data as inputs, along with published vector distribution maps. We used mosquito trapping data from Spain, France, Italy and Morocco to calibrate the model, and we produced monthly maps of abundance of the five vectors for the whole studied area. We then evaluated the model performances by assessing the correlation between field data and model predictions. Finally, we performed a sensitivity analysis to identify the main influential parameters. The model was able to reproduce most of the abundance peaks for the five mosquito species. Goodness-of-fit was high for Aedes species, especially for Ae. caspius, a highly competent mosquito for RVFV transmission, but lower for Culex species, with potential overpredictions in some regions. More knowledge is required about the presence and abundance of potential RVFV vectors in the Mediterranean Basin to improve predictions. However, this first model allows to identify seasons and areas with high vectors abundances that could be used in the future for surveillance of the disease.

While studies on mosquito population genetics have primarily focused on medically relevant species, fewer have examined the genetic population structure of mosquitoes from a diverse range of species within a single geographical area. The limited comparison between native and non-native species, as well as ecologically divergent species from the same region, hampers our ability to generalise previously described patterns in mosquito population genetics. This study uses the mosquito fauna of the Caribbean islands of Aruba, Curaçao and Bonaire as a case study to explore population genetic variation among both native and non-native mosquito species, as well as among native species occupying different ecological niches. We examine how genetic patterns relate to their population history and species-specific ecologies. Mitochondrial COII sequences were obtained from 258 mosquito specimens belonging to six species, occurring on all three islands. Sequences were used in haplotype network analysis to assess the genetic variation between mosquito populations of each of the six ecologically diverse species, which vary in both their population history and ecological niche. Both the genetic diversity and population genetic structure were found to differ strongly between sets of species, leading to a subdivision into three species groups: (1) non-native species with low genetic diversity across all three investigated islands, (2) locally native species with high genetic diversity and closely related haplotypes occurring on different islands and (3) locally native species with high genetic diversity and locally restricted haplotypes. Our results show that the population genetics of non-native and native species strongly differ, likely as a result of population history. Furthermore, the results suggest that mosquito species sharing the same area may display distinct population genetic structure, likely related to differences in their ecology and dispersal capacity. We suggest that addressing a broader range of species within a single area will benefit future research on mosquito population genetics to place observed patterns into a broader historical, ecological and evolutionary context.

Following the first record of Phlebotomine sand flies in Luxembourg in 2023, we performed during the summer 2024 the first extensive field survey investigating the sand fly fauna diversity and distribution in the Grand Duchy. Overall, 181 samples (insect batches/site/trapping method/date) were collected from 165 sites across the country (44 localities in 28 communes), mainly by running light traps but occasionally sticky traps and conducting resting catches. Only Phlebotomus mascittii was found, in a total of 15 samples collected at 10 localities, revealing 23 specimens (12 females and 11 males). More trapping effort might be implemented in the country to confirm the absence of Ph. perniciosus . Together with the first observations of 2023 (at two localities), the occurrence of Ph. mascittii has increased to 12 localities in total, which are widely distributed over south Luxembourg, but with an overall low density. This low density suggests the risk for Leishmania transmission in Luxembourg, if introduced, to be very low. The two northernmost localities where sand flies were detected are in the commune of Rosport-Mompach. Our data do not suggest northwards spread of sand flies, but they complete the distribution data north to the Alps, demonstrating they are more widespread than previously known. Further assessing the risk for sand fly-borne diseases in Luxembourg would request the acquisition of information on Leishmania infections in dogs for imported cases and, if existing, suspected locally acquired cases. Additional entomological field surveys may be implemented to further determine the local distribution of sand flies, the period of activity of adults, the abundance, or the presence of pathogens in insects when their circulation is suspected.

The Asian tiger mosquito, Aedes albopictus, is currently the most widespread invasive mosquito species in the world. It poses a significant threat to human health, as it is a vector for several arboviruses. We used a SNP chip to genotype 748 Ae. albopictus mosquitoes from 41 localities across Europe, 28 localities in the native range in Asia, and 4 in the Americas. Using multiple algorithms, we examined population genetic structure and differentiation within Europe and across our global dataset to gain insight into the origin of the invasive European populations. We also compared results from our SNP data to those obtained using genotypes from 11 microsatellite loci (N = 637 mosquitoes from 25 European localities) to explore how sampling effort and the type of genetic marker used may influence conclusions about Ae. albopictus population structure. While some analyses detected more than 20 clusters worldwide, we found mosquitoes could be grouped into 7 distinct genetic clusters, with most European populations originating in East Asia (Japan or China). Interestingly, some populations in Eastern Europe did not share genetic ancestry with any populations from the native range or Americas, indicating that these populations originated from areas not sampled in this study. The SNP and microsatellite datasets found similar patterns of genetic differentiation in Europe, but the microsatellite dataset could not detect the more subtle genetic structure revealed using SNPs. Overall, data from the SNP chip offered a higher resolution for detecting the genetic structure and the potential origins of invasions.

With the worldwide spread of the Asian tiger mosquito, Aedes albopictus, the number of autochthonous cases of exotic arboviral diseases, such as dengue or chikungunya, is increasing in temperate regions. In Europe, pyrethroids are the only insecticides allowed for the abatement of adult mosquitoes and are thus crucial for limiting ongoing arbovirus transmission. Despite this and the report of resistance rising in vector populations worldwide, information on the pyrethroid resistance status of vector populations and knowledge on resistance mechanisms is widely lacking. Genotyping of knockdown resistance (kdr) mutations situated within the target site of pyrethroids, i.e., the voltage-gated sodium channel (VGSC), and associated with pyrethroid resistance, is a cost-effective approach to investigate the spread of resistance in a population. Herein, we describe the European-wide distribution of two kdr mutations, i.e., I1532T and F1534C, in Ae. albopictus and evaluate their co-occurrence with another well-characterized kdr mutation, V1016G. Genotyping of the kdr mutation F1534C was performed by allele-specific PCR for 1732 Ae. albopictus specimens sampled in 19 European countries; for a subset of 419 specimens mutation I1532T was also genotyped by sequencing. For all samples, information on mutation V1016G was available, allowing evaluation of the co-occurrence of kdr alleles. Mutation 1534C was detected in nine sites from six countries at an overall frequency close to 5

Abstract Sand flies are vectors of Leishmania spp. protozoa, phleboviruses and Bartonella bacilliformis. In this study we surveyed areas of central-western Europe, encompassing the northern limit of the known sand fly distribution, and investigated the relationship between their presence and environmental variables. In this area, very limited occurrence data exists, none of them recent. Sampling was performed in July and August 2023 using CDC-light traps, sticky traps and human landing captures, at 179 selected sites in 48 municipalities. A total of 55 sand fly specimens were collected at 11% (20/179) of the sites sampled – including 16 sites in France, 2 in Luxembourg and 1 in Germany – comprising the first published records for Luxembourg and the Trier-Saarburg County of Germany. No sand flies were detected in Belgium or in the Netherlands. Two species were captured: Phlebotomus mascittii (37 females, 2 males) and Ph. perniciosus (1 female, 15 males). The latter species was only found in Savoie, the southernmost region sampled in France, while the former species was detected as far north as latitude 50°N. Logistic regression modelling indicated that the probability of sand fly presence gradually decreased with increasing latitude and altitude (P < 0.05), and it was not associated to other analysed landscape features in the proximity of the traps. The study confirms and provides new evidence for the presence of sand flies in areas of Western Europe and highlights the need to be aware of potential autochthonous transmission of sand fly-borne pathogens in these areas.

Background: Despite their medical and veterinary importance, little is known about the general patterns in genetic population structure of mosquitoes. The scarce information that is available comes from a small subsample of cosmopolitan (and often pathogen-transmitting) species. This greatly hampers our ability to generalise previously described patterns of variation in mosquito population genetics to global mosquito biodiversity. This study aimed to explore variation in population genetics of species from a wide range of ecological niches and how variation in these patterns relates to species-specific ecologies and population history, using the mosquito fauna of the Caribbean islands of Aruba, Curaçao, and Bonaire as a case study. Methods: Mitochondrial COII sequences were obtained from 258 mosquito specimens belonging to six species, occurring on all three islands. Sequences were used in phylogenetic analysis and haplotype network analysis to assess the genetic variation between mosquito populations of each of the six ecologically diverse species, which vary in both their population history and ecological niche. Results: Both the genetic diversity and population genetic structure were found to differ strongly between sets of species, leading to a subdivision into three species groups: i) non-native species with low genetic diversity across all three investigated islands; ii) locally native species with high genetic diversity and closely related haplotypes occurring on different islands; iii) locally native species with high genetic diversity and locally restricted haplotypes. Conclusions: Our results show that the population genetics of non-native and native species strongly differ, likely as a result of population history. Furthermore, the results suggest that native populations may display distinct population genetic structure, which is likely related to differences in their ecology and dispersal capacity. Based on these results, we hypothesize that similar contrasts in mosquito population genetics along historical and ecological axes may be present worldwide.

Abstract In the frame of the entomological VectorNet network and its capacity building activities, we collected original mosquito distribution 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 posted early 2022 on iNaturalist, we targeted the exotic Aedes species in our sampling strategy, but also collected data on other mosquito species. Besides some adult catches, we mainly collected mosquito immature stages from artificial and natural water containers but occasionally from other aquatic habitats. In addition, we collated citizen data and modelled the distribution of Ae. japonicus in Europe incorporating the newly collected data. During this snapshot field study, a total of 162 samples, including 139 yielding mosquitoes, were taken from 111 locations across 47 administrative units, resulting on the detection of 22 mosquito taxa. Our study provides the first substantiated records of Ae. japonicus and Anopheles petragnani in Poland (the second confirmed by molecular identification). While Ae. japonicus is clearly established over a large part of the country, no other exotic mosquito species was detected. The presence of Ae. japonicus was also confirmed at one location by four citizen records submitted 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 suggests higher environment suitability in Central and Eastern Europe than has been previously estimated. Aedes japonicus is probably widespread in the Czech Republic and Slovakia, and might soon colonise the bordering region of Ukraine. Its establishment extends the putative mosquito vector list for West Nile and Rift Valley fever viruses in Central Europe.

Abstract We report occurrence data of mosquitoes in Scotland which were routinely collated by the British Mosquito Group for the period 1886 to 1993 (232 records), and by the Mosquito Recording Scheme since 2005 (11 records). We also report a set of new field data mainly based on mosquito immature sampling in aquatic habitats during the summers 1998 and 2012, in both Scotland (20 data) and England (11 data). The occurrences in Scotland (263 data in total) include a total mosquito fauna of 18 species. They include, for the British Isles, the northernmost record of Anopheles claviger sensu stricto, collected on Orkney, and the northernmost record of Culex pipiens, collected on Shetland, both in 2012. The latter is the northernmost mosquito record of Great Britain to date.

This article presents the current state of knowledge of mosquito species (Diptera: Culicidae) occurring in Poland. In comparison to the most recently published checklists (1999 and 2007), which listed 47 mosquito species, four species (Aedes japonicus, Anopheles daciae, Anopheles hyrcanus, and Anopheles petragnani) are added to the Polish fauna. Our new checklist of Polish mosquito fauna includes 51 species of mosquitoes from five genera: Aedes (30), Anopheles (8), Coquillettidia (1), Culiseta (7), and Culex (5). Aspects of the ecology and biology of the Polish mosquito fauna, with particular emphasis on newly recorded species, are discussed.

Abstract A snapshot mosquito field survey was conducted in the Republic of Ireland in April–May 2017 and 2018 (for the VectorNet project) to provide mosquito distribution data as there is a dearth of recent data available for that region. The occurrence data obtained serve as a baseline for a preliminary public and veterinary health risk assessment and to promote further targeted vector surveillance. Morphological identification was complemented by genetic analyses to determine the species identity of members of the Anopheles Maculipennis Complex and the Culex Pipiens Assemblage. A total of 52 samples, including 50 immature aquatic samples and 2 adult catches, were collected from 72 locations inspected and distributed over 30 of the 34 vice counties across the country. Seventeen mosquito taxa were collected, and here we provide the first records of Aedes geminus, Anopheles daciae and Culex torrentium for the Republic of Ireland. We also confirm the occurrence of both Anopheles algeriensis and Culiseta alaskaensis which have only been found once before in Ireland.