Journal of Medical Entomology

Aedes albopictus is a major arboviral vector whose global expansion, driven by human activities and climate change, poses a growing public health concern for a number of neglected tropical diseases in both tropical and temperate regions. As a poikilotherm, its biology and population dynamics are strongly influenced by temperature, thereby shaping disease transmission. To thwart and control its geographic expansion, effective vector control strategies are increasingly critical. Densoviruses (DVs), such as AalDV2, are being explored as mosquito viral biocontrol agents due to their restricted host range and ability to disseminate through oviposition sites. However, the influence of environmental parameters on the interactions between Ae. albopictus and AalDV2 remains poorly understood. This makes their performance under realistic, fluctuating thermal regimes difficult to estimate. In this study, we investigated the combined effects of temperature and AalDV2 exposure on Ae. albopictus survival and development across its full life cycle. Mosquitoes were reared under fluctuating temperature regimes (26-28 {degrees}C and 32-34 {degrees}C, 12:12 day[ndash]night cycles) and exposed to AalDV2 or a control treatment. Chronic exposure to 32-34 {degrees}C significantly reduced overall survival, decreasing median lifespan by approximately 10 days (HR=2.21, p=0.0018), with a deleterious effect increasing over time. It extended aquatic lifespan and increased pupal mortality. It also reduced adult lifespan in both sexes with a stronger effect in females. AalDV2 exposure had no significant effect on overall survival, stage-specific mortality, or adult lifespan. However, a significant interaction between viral exposure and thermal stress was detected on aquatic lifespan: AalDV2-exposed females showed further extended larval and pupal development specifically under the 32-34 {degrees}C regime, without any effect on survival. These results indicate that the biocontrol potential of AalDV2 cannot be assessed independently of thermal context: while lethal effects were absent under both fluctuating regimes, the prolongation of aquatic development by the virus under thermal stress may have indirect consequences for mosquito population dynamics that warrant further investigation.

Aedes aegypti mosquitoes are the primary vectors for dengue, yellow fever, chikungunya and zika virus transmission, posing significant public health risks. In Kenya, these viruses drive disease outbreaks especially, dengue and chikungunya with coastal Kenya being the most affected. Low-level circulation of the Zika virus has been reported in parts of the Kenyan coast, with confirmed cases reported in Lamu County between August to September 2024. Except for yellow fever, there are no approved vaccines or therapeutics, hence vector control remains the most effective means of protection. However, prolonged exposure to insecticides can lead to resistance, threatening these interventions. Therefore, monitoring resistance in mosquito populations is critical to allow for appropriate interventions using effective chemical classes to prevent disease outbreaks. This study aimed to establish the levels of resistance to pyrethroids, and associated markers, among Ae. aegypti populations in sections of Lamu County where there had been a recent localized outbreak of Zika. Mosquito eggs were collected from Mkomani, Kashmir, and Kandahar villages in Lamu County, reared and tested for susceptibility to three pyrethroid insecticides (0.75% permethrin, 0.05% Alpha-cypermethrin and 0.05% deltamethrin) using WHO tube assays. Genotyping of knockdown resistance (kdr) mutations L982W, S989P, A1007G, V1016G/I, and F1534C was done using Sanger sequencing. Association between resistant phenotypes and genotypes were inferred. The results varied between the three pyrethroids with high resistance to permethrin observed (6-15% mortality), for deltamethrin mortality ranged between 53-57%, while for alphacypermethrin 88%-99% mortality was observed. Two mutation types and six genotypes were identified at F1534. No other kdr mutations were detected. The CC genotype was significantly associated with 0.75% permethrin resistance in Ae. aegypti populations (OR = 2.87, 95% CI: 1.34-6.17, P = 0.0036). The current data show that Ae. aegypti from Kandahar, Kashmir and Mkomani villages in Lamu County have developed very high resistance to permethrin, and varying resistance to other pyrethroids, thus threatening pyrethroid-based control strategies in this region, highlighting the need for alternative strategies to control the vector for arboviruses.

Locally acquired arboviral infections are an increasing public health concern in the United States. Aedes aegypti and Culex quinquefasciatus, vectors of dengue virus and West Nile virus, respectively, are established in regions where local transmission has been reported. Seasonal variation in mosquito abundance affects vector density, human-vector contact, and arbovirus transmission risk. The aim of this study is to investigate seasonal variations in Ae. aegypti and Cx. quinquefasciatus population dynamics in Miami-Dade County, Florida; Maricopa County, Arizona; and Clark County, Nevada. Monthly relative abundance, average mosquitoes collected per trap-night, normalized abundance ratios, and seasonal-trend decomposition were used to evaluate species- and location-specific seasonal patterns. Mosquito population dynamics differed by species and location. In Miami-Dade County, the two species showed seasonal turnover, with Cx. quinquefasciatus peaking during winter and spring and Ae. aegypti peaking during summer. In Maricopa and Clark counties, both species peaked primarily between August and September. Species dominance also differed by site, with Ae. aegypti more abundant than Cx. quinquefasciatus in Maricopa County and Cx. quinquefasciatus more abundant than Ae. aegypti in Clark and Miami-Dade counties. Seasonal decomposition showed that Ae. aegypti peaked earlier in Miami-Dade County than in Maricopa and Clark counties, whereas Cx. quinquefasciatus showed a spring peak in Miami-Dade County and bimodal seasonal patterns in Maricopa and Clark counties. These results suggest that mosquito population dynamics are species- and location-specific and support the use of local surveillance data to guide the timing of mosquito control and arbovirus preparedness.

BackgroundAnopheles gambiae sensu lato (s.l.) is the primary vector of malaria in sub-Saharan Africa. Although insecticide-based vector control has been central to prevention, the widespread emergence of insecticide resistance poses a serious biological threat to control efforts. Effective resistance monitoring is essential for sustaining vector control but remains highly limited in malaria-endemic hotspots. Here, we assessed pyrethroid and DDT resistance intensity and the frequency of the L1014F knockdown resistance (kdr) mutation in Anopheles gambiae s.l. populations from Sokoto, north-western Nigeria. MethodologyResistance status and intensity to five insecticides were determined in adult Anopheles reared from larvae collected in 2021 and 2022 using the World Health Organization (WHO) tube test and Centers for Disease Control and Prevention (CDC) bottle bioassay, respectively. A subset of resistant mosquitoes was analyzed using PCR-based diagnostic assays to identify species within the Anopheles gambiae complex and to genotype for the West African kdr mutation (L1014F). ResultsHigh knockdown times (KDT) were observed, with KDT50 ranging from 38 to 91 minutes and KDT95 from 104 to 678 minutes, indicating increased resistance levels across all insecticides. In 2021, resistance was detected to DDT, lambda-cyhalothrin, and permethrin, while susceptibility to alpha-cypermethrin (98%) and suspected resistance to deltamethrin (91%) were recorded. In 2022, a general increase in resistance to all insecticides was observed, with mortality rates ranging from 41% to 81%. High resistance intensity was observed against DDT, while permethrin and alpha-cypermethrin exhibited low resistance intensity in both years, failing to reach 10x the diagnostic dose. Deltamethrin and lambda-cyhalothrin showed low to moderate resistance intensity. The 1014F kdr mutant genotype was widely distributed (68.1%) across species and years. Allele frequencies were higher in An. gambiae s.s. (0.83) than in An. arabiensis (0.71), with significant deviations from Hardy-Weinberg equilibrium (p < 0.05), except for An. gambiae s.s. in 2021 (p = 0.7). ConclusionThese findings reveal a concerning increase in key insecticide resistance among Anopheles populations in Sokoto, underpinned by strong genetic mechanisms. This underscores the urgent need for integrated vector management strategies to sustain effective vector control efforts in the region.

Mosquito-borne viruses like dengue, Zika, and chikungunya pose increasing health risks in the United States due to the expanding range of Aedes albopictus, a highly invasive mosquito species that now has a global distribution. Aedes albopictus thrive in artificial containers associated with anthropogenic land use, allowing populations to reach high numbers in urban and suburban environments. While the global spread of Ae. albopictus has been well-characterized, the effects of heterogeneous urban landscapes on dispersal and gene flow at fine spatial scales remain unclear. This study analyzed the genetic connectivity of Aedes albopictus populations collected in Wake County, North Carolina in 2018. We used single nucleotide polymorphisms SNP data from double-digest restriction-enzyme associated DNA sequencing (ddRADseq), and examined genetic connectivity through principal component analysis (PCA) and genetic network analysis. We then evaluated migration and source sink dynamics using a Bayesian approach for SNP data (BA3-SNP). We found little evidence of genetic clustering or isolated populations of Ae. albopictus in Wake County, suggesting high gene flow between sites. Migration analysis demonstrated asymmetric gene flow from rural to urban regions within Wake County, with greater gene flow occurring between and within urban regions. These findings suggest that Ae. albopictus populations demonstrate substantial gene flow within local metropolitan areas, with urban city centers serving as genetic sinks and surrounding suburban and rural regions serving as sources. This study highlights how heterogeneous landscapes shape mosquito population connectivity and migration at fine spatial scales, which is critical for informing vector control and public health intervention strategies.

BackgroundAttractive Targeted Sugar Baits (ATSBs) are a promising, environmentally friendly approach for mosquito control, but the direct field application, scalability and long-term effectiveness of ATSBs across diverse mosquito species remain significant challenges. Methodology/Principal FindingsWe assessed the efficacy of a genetically engineered RNA interference (RNAi) yeast strain (Sh.463_56.10R) formulated in three sugar baits, soda (Coca-ColaTM), 10% sucrose, and a commercial mosquito bait (BaitStabTM), on Aedes, Anopheles and Culex mosquitoes. All RNAi yeast bait formulations induced significantly higher mean mortality (87-100%) compared to the control groups (0-9%; P<0.0001), but mosquitoes exhibited a higher feeding preference for RNAi yeast-soda baits, which induced mortality rates of 94-100% (P < 0.0001) recorded across all mosquito species. Additionally, to assess the competitiveness of the RNAi yeast-soda bait to other tropical sugar sources, semi-field choice assays were conducted in Trinidad, West Indies using competing flowering plants and fruits typically found in residential environments. The RNAi yeast-soda ATSB continued to perform well in the presence of competing floral and fruit sugar sources during both Aedes albopictus and Culex quiquefasciatus trials, though the presence of several fruits and flowers did reduce A. aegypti mortality, suggesting that further field testing will be necessary. The residual activity of the Sh.463_56.10R + soda formulation was retained for at least 14 months, with sustained 100% mortality in C. quinquefasciatus and 93-100% mortality in Aedes aegypti, Anopheles gambiae and Anopheles stephensi. The RNAi yeast-soda ATSB also performed well in semi-field studies performed with a prototype soda bottle feeder. Conclusions/SignificanceThis study demonstrates the potential of soda-baited RNAi yeast as a potent, long-lasting, and scalable platform for ATSB-based mosquito control as a component of integrated vector management programs. Author SummaryMosquito-borne diseases continue to affect millions of people worldwide, and current mosquito control methods face challenges such as low public uptake, insecticide resistance and environmental concerns. Here we evaluated a new and environmentally friendly approach to mosquito control using ATSBs. We tested genetically engineered species-specific yeast producing RNAi molecules capable of killing mosquitoes that feed on it. We mixed the yeast with three different sugar baits, including soda (Coca-ColaTM), 10% sucrose, and the commercial mosquito bait BaitStabTM formulation, and evaluated how well they worked against different mosquitoes. The results showed that the RNAi yeast mixed with soda was the most effective, killing up to 100% of mosquitoes in laboratory and outdoor tests. The bait remained effective in the presence of many competing natural tropical fruit and floral sugar sources. Remarkably, the bait, which can be delivered in a soda bottle feeder, stayed active for at least 14 months under simulated field conditions. These findings suggest that soda-based RNAi yeast baits could provide a practical, long-lasting and scalable tool for mosquito control and may help strengthen future strategies to reduce mosquito-borne diseases.

1In 2024-2025 a multi-centre study involving seven international laboratories was conducted with the support of the World Health Organization (WHO). The aim of the study was to establish and validate discriminating concentrations (DCs) in WHO bottle bioassays for monitoring susceptibility to broflanilide and isocycloseram in Anopheles gambiae s.s., An. funestus, An. stephensi and Aedes aegypti. The following values are recommended for adoption as DCs for broflanilide: 10 {micro}g/bottle for An. gambiae and Ae. aegypti, 15 {micro}g/bottle for An. funestus, and 25 {micro}g/bottle for An. stephensi. The recommended DCs for isocycloseram are 15 {micro}g/bottle for Ae. aegypti, 30 {micro}g/bottle for An. gambiae, 50 {micro}g/bottle for An. stephensi, and 60 {micro}g/bottle for An. funestus. Based on the experiences of conducting this study, which represents the application of a generic protocol for establishing discriminating concentrations produced by the WHO, technical recommendations are made on the generation and analysis of DC data for insecticides in future.

This data paper presents a curated, georeferenced dataset of the frequencies of the two main target site mutations (V1016G and F1534C) associated with resistance to pyrethroid insecticides in Aedes albopictus in Italy. Populations were collected in 102 out 107 Italian provinces between 2023 and 2025. Specimens were sampled by members of the Mosquito Insecticide Resistance Italian Network (MosqIRIT) as part of RN2 activities within the INF-ACT project. Genotyping was performed on 3,517 individuals by specific allele-specific PCR assays. Each record includes metadata on sampling site, administrative location, developmental stage, collection method, and mutation-specific genotype frequencies. To support spatial analysis modelling effort, the dataset integrates geographic, eco-climatic, and demographic data. This resource will support mosquito control programs, pyrethroid resistance monitoring and managing, as well as ecological modelling, and is compliant with the FAIR data program.

BackgroundAedes albopictus is among the worlds most invasive mosquito species and an important vector of dengue, Zika, and chikungunya viruses. Its global spread has been strongly associated with human-mediated transport and international trade, particularly through commodities such as used tires and ornamental plants. However, integrative studies combining population genetics, microbial symbiosis, and trade connectivity remain limited in Latin America, constraining understanding of invasion dynamics and dispersal processes. MethodsAedes albopictus populations from five Colombian departments sampled between 2019 and 2023 were analyzed using eight microsatellite loci and a [~]1.3-kb mitochondrial COI fragment. Wolbachia infection and lineage composition (wAlbA/wAlbB) were evaluated by PCR, and arbovirus detection (DENV, CHIKV, ZIKV) was performed using multiplex RT-PCR. Nuclear and mitochondrial differentiation (FST, {Phi}ST), mito-nuclear discordance, and trade-related connectivity were evaluated in relation to geographic, national transport, and international trade variables derived from customs databases. ResultsMicrosatellite analyses revealed admixed but structured populations consistent with multiple introductions and contemporary gene flow. Colombian populations showed nuclear genetic affinities with Asian, European, and North American populations, supporting a complex invasion history involving multiple geographically distributed lineages. In contrast, mitochondrial COI data showed evidence of regional genetic structure and heterogeneous mito-nuclear discordance among several population pairs. Notably, nuclear and mitochondrial markers captured contrasting dimensions of the invasion process: nuclear differentiation was positively associated with international trade intensity, particularly shipment frequency and used tire importation, whereas mitochondrial differentiation retained stronger regional structure and showed no detectable association with trade-related variables. Wolbachia prevalence ranged from 34% to 100% across departments and showed exploratory patterns consistent with localized mitochondrial differentiation. Natural detection of DENV and CHIKV RNA in larvae provided evidence of local arbovirus circulation. ConclusionsIntegrating population genetics, trade connectivity, and Wolbachia screening supports a scenario in which the Colombian invasion of Ae. albopictus has been shaped by multiple introductions, contemporary human-mediated connectivity, and partially discordant mito-nuclear histories. These findings highlight how different genomic compartments retain complementary signatures of invasion dynamics, with contemporary trade-associated connectivity primarily reflected in nuclear structure and regional lineage persistence retained in mitochondrial variation. Author SummaryThe Asian tiger mosquito, Aedes albopictus, is one of the worlds most invasive mosquito vectors and continues to expand across Latin America through human transportation and trade networks. However, the processes shaping its spread in the region remain poorly understood. We combined population genetics, international trade data, Wolbachia screening, and arbovirus surveillance to investigate the invasion dynamics of Ae. albopictus in Colombia. Our results revealed evidence of multiple introductions and ongoing genetic admixture, with international trade connectivity emerging as an important predictor of contemporary nuclear genetic structure. In contrast, mitochondrial DNA retained stronger regional patterns, generating heterogeneous mito-nuclear discordance among populations. These findings suggest that different genomic compartments retain distinct signatures of the invasion process, with trade-associated connectivity reflected primarily in nuclear variation and stronger regional structure preserved in mitochondrial lineages. More broadly, our study highlights the complex invasion dynamics of Ae. albopictus in Latin America illustrates how integrating genetics and human connectivity data can improve understanding of invasive vector spread.

Insecticide treated nets (ITNs) remain one the frontline tool in malaria control in Africa. The synergist piperonyl butoxide (PBO) has been incorporated into ITNs to combat pyrethroid resistance and these pyrethroid-PBO ITNs are now in widespread use across Africa. PBO is known to inhibit the degradation of pyrethroids and other insecticide classes, but little is known about other biological or behavioural effects of PBO exposure. This work assessed the impact of PBO on Anopheles gambiae s.l. male longevity as well as female host-seeking and blood feeding behaviours using laboratory assays. PBO had an immediate impact on blood feeding of female An. gambiae s.l. whereas the effect was not observed 24h post-exposure. Kaplan-Meier survival curves showed a significant difference in mosquito longevity post-exposure to PBO with male mosquitoes living nearly three times as long if exposed to control papers compared to PBO. In olfactometer assays, after exposure to control papers, control mosquitoes were significantly more attracted to host-odours, however, this attraction preference was reversed following PBO exposure. This study shows that in experimental assays, PBO has other effects on mosquito physiology and this is likely to contribute to the impact of pyrethroid - PBO ITNs in vector control programmes.

Despite extensive efforts to understand the population biology and ecology of the African malaria mosquitoes questions regarding their movement pattern, survival, and population size persist, reflecting methodological limitations. Site fidelity, in which mosquitoes return to feeding sites, resting sites, or oviposition sites remain debated. Mark release recapture (MRR) studies are vital to address such questions. Using locality- and date-specific DNA tags in fluorescent spray, we carried out a continuous MRR in a Malian village from September to December 2019 with three days interval between capture and release across seven zones. A total of 12,937 Anopheles gambiae s.l. (7,455 females) were captured during 35 indoor collections. Handling related mortality was 3.4%., A. coluzzii predominated (89.7%), followed by A. gambiae (9.4%), and A. arabiensis (0.9%). Overall recapture rate was 1.05% (N=129). Contrary to the site-fidelity hypothesis, the distribution of recaptured mosquitoes across zones (regardless of their zone of release) was similar to the distribution of the captured mosquitoes (r=0.97, P<0.001), with 70% recaptured in a different zone. There was no difference in distance moved between sexes, but males average distance increased over time since release, whereas females distance remained unchanged. Simulated movements (across released points), with equal probability to reach any of the village houses predicted actual distance moved by mosquitoes. The regression of observed distance from each zone over predicted had a slope of 1 (r2=94%, P=0.006), suggesting that the layout of the capture area greatly affected the results. The average days post release (minimum age of wild captured mosquitoes) for recaptures was 6.4 d with the longest being 30 d. No seasonal and sex related difference in minimum age were detected. The corrected probability of daily survival (PDS) was 94% and the daily increase in sporozoite rate was 4.9%. Limiting the recapture duration period showed that PDS increased with recapture duration from 74% to 86% (12 to 30 d, uncorrected). Thus, larger recapture area and longer recapture duration are needed to obtain accurate estimates of movement range and of daily survival.

Wolbachia-mediated incompatible-insect technique (IIT) via wAlbB, wMel or wPip/wAlbA/wAlbB strains are promising approaches for suppressing wildtype Aedes mosquitoes and therefore Aedes-borne diseases. Yet, the effectiveness of this technique under climate change remains uncertain. Here, we evaluate the long-term robustness of male Wolbachia-infected mosquito releases to suppress wildtype Aedes aegypti and Ae. albopictus populations across future climate scenarios across diverse geographical regions. We compiled large publicly available datasets on Aedes abundance across Singapore, China, the European Union and the United States, historical and projected climatic conditions in these regions and conducted experiments to test the thermal stability of cytoplasmic incompatibility in Wolbachia-infected male Aedes aegypti and albopictus. A climatically-driven entomological model was developed and calibrated using a Bayesian approach to model observed Aedes population dynamics and infer area-specific climate-driven variation in mosquito life-history traits. We back-inferred historical mosquito abundance and projected mosquito abundance in future climate change scenarios incorporating experimental and locally inferred entomological parameters and then simulated the counterfactual implementation of IIT in these regions. We find that Aedes populations are projected to increase in most regions across all climate change scenarios from 2050-2100 even under high heat conditions in the absence of interventions. While we found that IIT can suppress wild-type populations effectively across all future scenarios and in high heat conditions, effectiveness was found to depend heavily on mosquito emigration rates, overflooding ratios, release intervals and release strategies Extensive robustness checks confirmed that the model reproduced historical temporal trends, captured the influence of individual parameters on outcome and was sensitive to changes in values of inferred parameters and implement policy. These findings demonstrate that IIT may be a robust vector control tool under future climate conditions.

Tunisia is considered a high-risk country for arboviral transmission, and the re-emergence of malaria. Vector control programs predominantly rely on insecticide-based interventions, however knowledge on the insecticide resistance status of local vectors is limited. Here, we determined the mosquito species composition and investigated the resistance status of disease vectors to insecticides, collected from two distinct ecological settings; urban setting and rural setting. Known insecticide resistance loci were molecularly analysed. A total of 210 mosquitoes were collected, representing three main genera: Culex (n = 119), Aedes (n = 79), and Anopheles (n = 1). Within the Culex genus, Cx. pipiens pipiens and Cx. pipiens hybrids were the predominant species in Monastir and Kairouan respectively. Amongst Aedes, Ae. albopictus was the most abundant species in Monastir, while Ae. caspius predominated in Kairouan. The knockdown (kdr) mutation L1014F was detected at both sites across the three Cx. pipiens biotypes. In contrast, Cx. perexiguus showed no kdr mutation in Kairouan and a low frequency in Monastir. Among Aedes species, kdr mutations were detected exclusively in Ae. albopictus, restricted to domain III (mutation I1532T). No mutations in the chs gene were identified in both populations. Aedes albopictus collected in Monastir exhibited a moderate copy number variation for both carboxylesterases 3 and 6. No mutations were detected in the Anopheles labranchia. Our study results indicate the suitability of diflubenzuron for Culex and Ae. albopictus control in central Tunisia, emerging pyrethroid resistance in both vector species, and possibly reduced organophosphate efficacy against Ae. albopictus.

Ixodes scapularis ticks transmit a number of pathogens important to human health, including Borrelia burgdorferi, the causative agent of Lyme disease. While I. scapularis is found across the Eastern United States, Lyme disease transmission is largely limited to the Northeast and Upper Midwest and is nearly absent in the South. This indicates that differences in northern versus southern clades of I. scapularis are associated with differences in Lyme disease transmission risk. I. scapularis is undergoing range expansion, including into the Great Plains region of the United States. Determining where I. scapularis populations in the Great Plains originated can inform future risk of Lyme disease transmission in this region. In this study, we use a population genomics framework to characterize diversity, structure, and B. burgdorferi infection rates of I. scapularis populations in the Great Plains region. We generated whole genome sequence data and single nucleotide polymorphism (SNP) datasets from I. scapularis ticks collected in Iowa, Kansas, Nebraska, and South Dakota to compare to publicly available data from across the species range. Our analysis of 200 I. scapularis SNP datasets indicated geographically well-defined populations that correspond to historical northern and southern ancestral clades of I. scapularis. Ticks from South Dakota, Iowa, and northeastern Nebraska are genetically similar populations from the Upper Midwest, while ticks from Kansas are more genetically similar to ticks from the Southeast. Ticks collected in the central eastern region of Nebraska, however, represent an evenly admixed population of both northern and southern genomic backgrounds. Analysis of B. burgdorferi reads from genomic datasets shows [~]50% infection rate in ticks from Iowa and northeastern Nebraska, whereas ticks from Kansas show no evidence of B. burgdorferi infection. Of note, evenly admixed ticks from the central eastern region of Nebraska also show no evidence of B. burgdorferi infection. These results provide further evidence that tick genomics may influence traits associated with B. burgdorferi infection status, and thus the potential for Lyme disease transmission. As the range of I. scapularis continues to expand, bringing historically isolated populations into contact, there is a clear need to understand the consequence of genomic admixture for B. burgdorferi transmission potential to inform future risk of Lyme disease in the United States.

BackgroundThe invasive mosquito Aedes koreicus has established populations in several European countries during the past decade, raising increasing public health concerns due to its potential role as a vector of pathogens. While species identification is primarily based on morphological characters, Ae. koreicus exhibits distinct morphological variants originating from mainland Korea and Jeju Island, which complicates surveillance and may lead to misidentification, particularly in regions where closely related species co-occur. To date, the genetic basis and population-level relevance of these morphological forms in Europe remain poorly understood. MethodsWe investigated the co-occurrence of two morphological forms of Ae. koreicus in Hungary, representing the first confirmed European location where both forms were detected sympatrically and even within the same breeding sites. Adult mosquitoes were morphologically characterised using diagnostic traits, and individuals representing both morphotypes were subjected to comprehensive genetic analyses. We sequenced multiple mitochondrial markers (COX1, COX2, COX3, ATP6, ND1, ND3) and the nuclear ITS2 region using Oxford Nanopore long-read sequencing. Phylogenetic reconstructions and haplotype network analyses were applied to assess genetic differentiation between morphotypes and to compare them with Aedes japonicus as a closely related reference species. ResultsAcross all analysed mitochondrial and nuclear markers, no genetic differentiation was detected between specimens identified as the "mainland" or "Jeju-do" morphological forms of Ae. koreicus. Phylogenetic and haplotype network analyses consistently grouped individuals independently of their morphotype, indicating a shared genetic background at the population level. In contrast, Ae. japonicus formed a clearly distinct genetic lineage, confirming the robustness of the applied markers for interspecific discrimination. ConclusionsOur results demonstrate that the observed morphological variability in Ae. koreicus populations are not underpinned by detectable genetic differentiation using commonly applied mitochondrial and genomic markers. These findings highlight the limitations of using morphology alone to infer population origin or structure and emphasise the need for heightened awareness of intraspecific variability in routine surveillance. Accurate morphological identification remains critical, particularly in citizen science-based monitoring programmes and AI-based automatization platforms, such as Mosquito Alert, to avoid confusion with morphologically similar invasive species. Further studies integrating genomic and ecological approaches are required to elucidate the mechanisms underlying morphological variability in this emerging vector species.

Understanding how vector ecology intersects with host behaviour is essential for predicting zoonotic disease risk in tropical ecosystems. We conducted a two-year field study (November 2016-October 2018) in a riverine forest in Sabah, Malaysian Borneo, to characterize mosquito communities and the spatial distribution of potential simian-malaria vectors. Mosquitoes were sampled on 44 nights using CO{square}-baited light traps repeatedly deployed along a 500 m transect at three distances from the river (0, 250, 500 m) and two vertical strata (ground and canopy), yielding 244 trap collections across repeated sampling nights. In total, 9,928 mosquitoes were collected, dominated by Culex spp. (9,079; 91.4%), whereas Anopheles spp. were rare (153; 1.5%); most remaining specimens were unidentified to genus, and species-level identification was limited primarily to Anopheles. Nevertheless, female Anopheles (n=57) were more frequently detected near the river and less commonly at intermediate distance, and tended to be captured more often in ground traps. Zero-inflated negative binomial GLMMs based on the full mosquito dataset indicated significant effects of river distance and height on mosquito abundance, while night-time temperature and humidity showed no detectable effects. The zero-inflated structure of the data further suggested that many zero captures reflected true absence rather than sampling variability. The Anopheles assemblage was dominated by An. balabacensis, and molecular screening of 57 females detected simian Plasmodium DNA in two individuals. Overall, these findings suggest that river-edge habitats may represent localized areas where vectors persist and where primates and human activities overlap, creating repeated opportunities for host-vector contact even when vector densities are low.

The global invasion of the Asian tiger mosquito Aedes albopictus has led to an increase in arboviral disease, including within Mesoamerica. Understanding vector invasion routes is important for public health because it directs biosecurity and identifies sources of adaptive allele spread. Panama is an important hub of global trade with opportunities for Aedes introduction through both maritime and overland routes but dispersal into the Isthmus has not yet been investigated. We therefore sought to investigate the population structure and invasion history of Ae. albopictus into Panama, targeting both its mitogenome and associated Wolbachia. Historical demographic analysis with Bayesian phylogeographic diffusion models and estimates of divergence revealed that Panamanian Ae. albopictus and its associated Wolbachia have a convergent evolutionary history resulting from multiple introductions. Both could be traced to Asian-derived lineages introduced via the Americas, with invasion primarily through the maritime trade of the Panama Canal rather than overland dispersal from neighboring Costa Rica. An investigation of the relative density of Wolbachia in Panama revealed that both the strains wAlbB and wAlbA were at a notably lower density compared to other worldwide locations. This finding has implications for arbovirus transmission and raises important questions about how Wolbachia density is impacted by the environment and impacts on population control. Overall, the Panama Canal is a key route for vector introductions into Mesoamerica.

Tickborne diseases are a significant burden in many parts of the world. In the upper Midwestern United States, Lyme disease is the most common tickborne disease. It is carried by Ixodes scapularis. This vector can also transmit the pathogens causing anaplasmosis, babesiosis, ehrlichiosis, and several more tickborne diseases in this region. There is also concern for other tick species, such as Amblyomma americanum, that are expanding their ranges northward. We launched a citizen science passive tick surveillance program in 2024 to investigate tick species ranges in the upper Midwest, as well as the pathogens carried by I. scapularis. We received over 12,000 ticks in the first two years of this program, primarily from Wisconsin. While we received submissions of adult A. americanum outside of their endemic range, we did not see evidence of establishment in our study area. We measured pathogen prevalence in adult female I. scapularis (n=707) and observed 51% positivity for Borrelia burgdorferi, 9% for Babesia microti, 9% for Anaplasma phagocytophilum, and 3% for Ehrlichia muris eauclairensis. Multiple pathogens were identified in 14% of tested specimens, and significant associations were observed between B. burgdorferi and B. microti, and B. burgdorferi and E. muris eauclairensis. Pathogen prevalences varied across time and geography. Our results can begin to inform risk assessment for tickborne diseases in our region. A non-technical version of this document with interactive maps is available here: https://storymaps.arcgis.com/stories/8008c9d710b5400599f3c6cf88b2c546 Our online data dashboard is available here: redcap.link/TICS

BackgroundMicroplastic (MP) pollution is an emerging environmental concern that extends beyond aquatic systems into terrestrial food webs. The mosquito Anopheles stephensi, a major malaria vector in Asia and the Middle East, undergoes complete metamorphosis and offers a useful model to examine cross-stage MP transfer. However, the physiological consequences of such exposure remain poorly understood. MethodsFluorescent polystyrene microplastics (1 {micro}m) were administered at six concentrations (0-300 mg L-1) under controlled laboratory conditions. Larvae were reared on standard fish pellets, and adults were maintained on a 10% sucrose solution. Fluorescence microscopy tracked MP ingestion and transfer across life stages. Larval weight, developmental timing, and survival were analyzed using ANOVA and Chi-square tests. ResultsOntogenic transfer of microplastics was confirmed from larvae to pupae (100%) and adults (94%). Increasing MP concentrations accelerated development by 1-2 days but significantly reduced survival, with mortality rising from 12% in controls to 64% at 300 mg L-1. Body weight declined consistently in a dose-dependent manner (p < 0.001). ConclusionThis study provides the first experimental evidence of ontogenic MP transfer in An. stephensi. Microplastic exposure alters development and survival, potentially affecting mosquito population dynamics and vectorial capacity, highlighting the need to incorporate MP pollution into vector ecology models.

Nature-Based Solutions are increasingly promoted to address current urban challenges. While their potential effects on vector-borne disease risks have been documented, data on Aedes albopictus, a known arbovirus vector, remain limited in France. A previous study showed that urban vegetation moderately increases the abundance of adult mosquitoes of this species, but the monitoring period lasted only six months. Using ovitraps, we monitored Ae. albopictus egg density dynamics over multiple years (2022 to 2024) and analysed its environmental predictors in various urban environments. We included lagged meteorological variables, land cover metrics, and the cumulated egg densities recorded in the previous weeks as environmental predictors. Both parametric (GLMM) and non-parametric (Random Forest) models were fitted to weekly egg counts per trap. Our findings highlight that (i) egg density dynamics were related to how vegetation classes structured the landscape, (ii) growing degree days and cumulated number of eggs recorded in specific lagged time windows were the main contributors to egg density, and (iii) the non-parametric and parametric models performed similarly in terms of prediction accuracy.