The research, led by Riccardo Piccinno and Anna Rodolfa Malacrida of the University of Pavia, together with colleagues at the Institut Pasteur in Paris and partners in Switzerland, Italy and the Balkans, set out to answer a deceptively simple question: do genetically distinct mosquito populations differ in their ability to transmit arboviruses? The answer, the authors report, is a clear yes, and the pattern they uncovered is striking. Neighboring mosquito populations with different genetic ancestries showed drastically different competence profiles for CHIKV and DENV, while geographically distant populations that share ancestry behaved similarly. In other words, for these viruses, where a mosquito’s genes came from matters more than where the mosquito lives.

To reach that conclusion, the team combined two complementary lines of evidence: population genetics and experimental vector competence assays. On the genetic side, they genotyped mosquitoes from an ancestral reference population in Guangzhou, China, and from ten adventive populations sampled across five Mediterranean regions, spanning Southern Switzerland, Northern and Central Italy, the Balkans and Greece. The markers of choice were highly polymorphic simple sequence repeats, or SSRs, which allow fine-scale discrimination of genetic lineages. Using the Bayesian clustering program STRUCTURE, the researchers assigned individuals to ancestry groups, and with the approximate Bayesian computation framework DIYABC-RF they reconstructed the demographic histories that produced the present-day genetic mosaic.

That history, the study finds, was anything but a single clean invasion wave. By combining historical records with demographic modeling, the authors show that the establishment of Aedes albopictus in the Mediterranean was driven by chaotic, discontinuous introductions of distinct lineages, followed by admixture events in which previously separated genetic backgrounds interbred. The result is high heterogeneity in both space and ancestry: populations separated by only a few hundred kilometers can carry markedly different genetic compositions, reflecting separate introduction routes, likely via the international trade in used tires and other commodities that has repeatedly ferried mosquito eggs across borders. This genetic patchwork, rather than a homogeneous expansion front, is the biological backdrop against which viral transmission now plays out.

The experimental half of the study measured vector competence using the standard trio of quantitative indices. Infection rate captures the proportion of mosquitoes in which the virus successfully establishes an infection in the midgut after an infectious blood meal; dissemination efficiency measures how many of those infected mosquitoes allow the virus to escape the midgut and spread to secondary organs, including the salivary glands; and transmission efficiency quantifies the fraction with virus present in the saliva, the prerequisite for onward transmission to a new host. Mosquitoes from each population were fed blood meals containing CHIKV strain 06.21, DENV-1, or ZIKV strain PE243, and these indices were scored at multiple days post-infection, specifically 7, 14 and 21 days, to track the temporal progression of infection.

Statistical analysis then linked the genetic and virological datasets. Univariate and multivariate models assessed whether population identity, ancestry group membership, and days post-infection were associated with each competence index. For CHIKV, the analyses identified day post-infection, population, and two ancestry components as significant factors associated with infection, with some ancestry fractions showing positive associations and others negative ones. For DENV, population and three ancestry components were significantly associated with infection rate, although the authors note that two of these lacked a biologically plausible monotonic trend across ancestry categories, meaning higher ancestry fractions did not simply translate into higher infection rates. For ZIKV, by contrast, no variable emerged as a significant predictor, suggesting that the genetic heterogeneity captured in this study does not translate into measurable variation in Zika competence among these populations.

The most consequential finding concerns CHIKV and DENV. Ancestry and population identity significantly influenced dissemination and transmission as well as infection, and the geographic pattern was counterintuitive: proximity did not predict similarity. Populations in neighboring geographical areas but with distinct ancestries exhibited drastically different competence profiles, whereas geographically distant populations sharing genetic ancestry displayed similar vector competence. This dissociation between geography and genetics implies that the introduction history of each local population, not local environmental conditions alone, has left a durable imprint on its capacity to transmit these viruses. It also suggests that the genetic variants governing viral infection and dissemination vary among source lineages, so that admixture has produced a mosaic of transmission potential across the region.

The public health implications are direct. Europe has experienced a rising trend of both imported and autochthonous arboviral infections in recent years, with chikungunya and dengue outbreaks recorded in Italy, France and elsewhere. If the mosquitoes buzzing in one province are substantially more competent vectors than those in the next, then uniform, region-wide control assumptions may misallocate resources. The authors argue that their results underscore the urgent need for localized, geographically tailored vector control strategies in Europe, in which surveillance and intervention intensity are calibrated to the actual transmission potential of local mosquito populations rather than to a generic regional estimate.

Methodologically, the study demonstrates the value of integrating fine-scale population genomics with standardized vector competence assays. The SSR-based genotyping, combined with STRUCTURE clustering and DIYABC-RF demographic inference, allowed the team to move beyond simple labels of origin and to quantify ancestry fractions within admixed populations. The logistic regression framework then made it possible to test the contribution of each factor while accounting for others, including the strong temporal effects of days post-infection that are well known to shape competence measurements. Supplementary analyses reported pairwise genetic differentiation among populations and detailed infection, dissemination and transmission rates stratified by virus, time point and population, providing a transparent record of the underlying data.

The work also carries broader lessons for invasion biology. Aedes albopictus is a textbook example of how global trade creates repeated, genetically diverse introductions, and this study shows that such demographic chaos can have functional consequences for disease transmission. As the climate warms and the mosquito’s suitable habitat expands northward, new introductions and further admixture are likely, potentially reshaping vector competence in currently lower-risk areas. Understanding the provenance of each new population, the authors suggest, should therefore become part of the risk-assessment toolkit, alongside entomological surveillance and case monitoring, if Europe is to anticipate rather than merely react to the next arboviral emergence.

Subject of Research: Vector competence and population genetics of invasive Aedes albopictus mosquitoes in the Mediterranean Basin

Article Title: Provenance and competence for CHIKV and DENV of Aedes albopictus populations

Article References: Piccinno, R., Madec, Y., Mariconti, M., Fiorenza, G., Carraretto, D., Forneris, F., Flacio, E., Coletti, S., Gasperi, G., Failloux, A.-B., & Malacrida, A. R. (2026). Provenance and competence for CHIKV and DENV of Aedes albopictus populations. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07705-6

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07705-6

Keywords: Aedes albopictus, Asian tiger mosquito, vector competence, chikungunya, dengue, Zika, population genetics, Mediterranean Basin, invasive species, arboviruses, genetic ancestry, vector control

The research team, led by Yu-hao Li, Zhi-zhao Zhang, Tong Fu, Xiao-bo Liu, Jian-xin Cui, Peng Cheng and Yu-hong Guo, drew on expertise from the National Institute for Communicable Disease Control and Prevention at the Chinese Center for Disease Control and Prevention, the Breeding Research Center of Insect Pests’ Natural Enemies at the Henan Institute of Science and Technology, and the Shandong Institute of Parasitic Diseases. Their goal was explicitly practical: to provide a scientific basis and theoretical support for the formulation of integrated control strategies against a mosquito whose expanding range continues to put hundreds of millions of people at risk of arboviral disease. Understanding how far and how long these insects can travel is a cornerstone of any attempt to predict outbreaks and target interventions.

To capture flight capacity in a controlled and comparable way, the researchers worked with a laboratory strain of Aedes albopictus under strictly standardized environmental conditions, holding temperature, humidity and photoperiod constant throughout the experiments. This was essential because ambient conditions are known to influence insect metabolism and muscle performance, and any uncontrolled variation could have confounded the comparisons between sexes and age classes. Male and female adults were tested at a finely resolved series of ages: every day from one to ten days after emergence, and then again at fifteen, twenty and twenty-five days of age, giving a total of thirteen age points that trace the full arc of adult physiological development.

The central instrument of the study was the flight mill, a classic tethered-flight technique that has been used for decades to quantify the flight potential of insects ranging from moths to beetles to mosquitoes. In a flight mill apparatus, an insect is attached to a lightweight rotating arm and flies in circles; sensors record the number of rotations, which can be converted into cumulative distance, total flight duration and average speed. Because the insect flies against minimal resistance in still air, flight mill measurements do not reproduce the exact aerodynamics of free flight in the field, but they are widely regarded as a robust proxy for an individual’s intrinsic flight capacity, allowing large numbers of insects to be compared under identical conditions.

For each mosquito, the team measured three parameters: cumulative flight distance, cumulative flight duration and average flight speed. These three metrics capture complementary dimensions of flight performance. Distance reflects overall dispersal potential, the quantity most directly relevant to how far a mosquito could carry a virus from one habitat patch to another. Duration reflects endurance, the ability to sustain flight over time, which matters for insects that must traverse hostile or resource-poor landscapes. Average speed reflects the intensity of flight effort and the mechanical power output of the flight muscles. Analyzing all three together gives a far richer picture of flight biology than any single metric alone.

Statistical analysis was carried out with generalized linear models, or GLMs, fitted with a Gamma distribution and a log link function, an approach well suited to strictly positive, right-skewed response variables such as distances and durations. Sex and age were entered as fixed factors, and their interaction, sex multiplied by age, was tested using likelihood ratio tests. This modeling framework allowed the researchers to ask not only whether males and females differ and whether flight changes with age, but also whether the trajectory of age-related change itself differs between the sexes, a subtler question that turns out to be central to the biology of this species.

The results were clear and, in places, striking. For cumulative flight distance, all three effects were significant: age mattered, sex mattered, and the interaction between sex and age mattered as well. Across the sampled ages, females displayed a significantly longer mean cumulative flight distance than males, confirming that the sex responsible for blood feeding and pathogen transmission is also the sex with the greater dispersal engine. For cumulative flight duration, age and the sex-by-age interaction were significant, although sex alone was not, meaning that the endurance gap between males and females emerges and shifts across the adult lifespan rather than being a constant difference. For average flight speed, both sex and age had significant main effects, but there was no significant sex-by-age interaction, indicating that the speed difference between the sexes remains comparatively stable as the insects grow older.

Taken together, these patterns demonstrate distinct age-related changes and sexual dimorphism in the flight capacity of Aedes albopictus, with the dimorphism itself varying dynamically across ages. The authors interpret this as highly consistent with mosquito physiological development and ecological functional differentiation. In biological terms, the story makes sense: newly emerged adults must complete sclerotization and reproductive maturation, flight muscles and energy reserves change over the first days of adult life, and females in particular undergo cycles of host seeking, blood digestion and egg development that reshape their energetic priorities. Males, whose ecological role centers on locating mates rather than seeking blood hosts, face different selective pressures on sustained flight, and the data suggest these pressures translate into measurably different flight trajectories.

The public health implications of the study are considerable. Aedes albopictus has spread from its native range in Southeast Asia across every inhabited continent over the past several decades, aided by the global trade in used tires and other water-holding containers that harbor its eggs and larvae. Because female mosquitoes can transmit dengue, chikungunya, Zika and yellow fever viruses, quantitative estimates of how far females of a given age can fly feed directly into models of epidemic spread, surveillance design and the placement of traps and control barriers. The authors emphasize that their findings offer a quantitative basis for predicting the dispersal potential of the species and for optimizing the timing and targets of control measures, information they describe as being of great reference value for the precise prevention and control of mosquito-borne infectious diseases such as dengue fever.

The study also illustrates a broader principle in vector biology: control programs that ignore the age structure and sex structure of vector populations may misallocate resources. If flight capacity peaks and declines at specific ages, then interventions aimed at interrupting dispersal, such as source reduction around breeding sites, spatial repellents or the release of sterile or Wolbachia-infected males, can be timed and targeted more effectively when the flight behavior of each sex and age class is known. Conversely, assuming that all adults pose an equal dispersal risk could lead to surveillance gaps precisely where and when the strongest fliers are active. By anchoring those assumptions in systematic flight mill data and rigorous statistical modeling, this research turns a basic entomological question into actionable epidemiological knowledge, and it underscores how much practical value can still be extracted from carefully executed laboratory studies of a familiar backyard pest.

Subject of Research: Age- and sex-dependent flight capacity of the mosquito Aedes albopictus measured by tethered flight

Article Title: The potential flight capacity of Aedes albopictus

Article References: Li, Y.-H., Zhang, Z.-Z., Fu, T., Liu, X.-B., Cui, J.-X., Cheng, P., & Guo, Y.-H. (2026). The potential flight capacity of Aedes albopictus. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07721-6

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07721-6

Keywords: Aedes albopictus, Asian tiger mosquito, flight capacity, flight mill, tethered flight, sexual dimorphism, mosquito age, vector biology, dengue, mosquito-borne disease, dispersal, Parasites & Vectors

The invasive mosquito has expanded its range across German cities in recent years, creating a nuisance for residents and a genuine public health concern because the species can transmit pathogens such as dengue, chikungunya and Zika viruses under suitable conditions. While intensive control and monitoring programs have demonstrated that local populations can be suppressed, these efforts are labor-intensive and expensive, prompting scientists to search for ways to target limited resources more efficiently.

In the new research, published in the journal Parasites & Vectors, the team focused on a 121-hectare suburban area in Pfaffengrund where active mosquito control was already underway. As part of routine control measures, breeding sites on 1,455 land parcels were repeatedly recorded between May and September 2023, offering an unusually detailed census of where water-holding containers suitable for mosquito larvae could be found. In parallel, egg counts from 39 ovitraps, standard surveillance devices that attract gravid females to lay eggs on wooden paddles or similar substrates, provided a direct measure of egg-laying activity across the neighborhood.

The statistical analysis hinged on generalized linear models and generalized linear mixed models, tools that allowed the researchers to test how building type moderated the effect of control measures on breeding sites, and how the composition of the surrounding urban landscape influenced trap counts. For each ovitrap, the team examined circular buffers of 100, 200 and 300 meters, calculating the proportion of parcels occupied by single-family houses, terraced houses and multi-family buildings, along with breeding site availability and the presence of parcels that were not included in control activities. Separate models were fitted for each buffer size and their performance was compared to identify the spatial scale that best explained the observed patterns.

The results were striking in their consistency. Terraced building plots contained the largest number of breeding sites, while multi-family house plots contained the fewest. This pattern likely reflects the structural features of terraced housing, where small private gardens, narrow courtyards and dense rows of interconnected properties offer numerous sheltered niches for water-collecting containers, from flower pot saucers to rain barrels, while shared access can complicate inspection and control efforts.

Building type also shaped the landscape-level signal in the ovitrap data. A higher share of terraced building plots within the surrounding area was associated with higher maximum egg counts in nearby traps, indicating that females were finding more favorable oviposition opportunities in these microhabitats. The researchers interpreted maximum egg counts as a measure of peak reproductive pressure at a location, making it a sensitive indicator of where mosquito populations were concentrating their egg-laying effort.

Perhaps counterintuitively, maximum egg counts were lower when the share of uncontrolled building plots in the buffer was higher and when more large breeding sites were present. The authors suggest that when untreated parcels and substantial breeding habitats dominate an area, female mosquitoes may disperse their eggs across those natural and semi-natural containers rather than concentrating them in the artificial attractants of ovitraps, diluting the apparent trap signal even where actual mosquito abundance may be high. This underscores a key lesson of surveillance ecology: ovitrap counts reflect both mosquito activity and the availability of competing breeding options in the environment.

Scale mattered as well. The best model performance emerged at a buffer radius of 200 meters, suggesting that the relevant neighborhood for predicting egg-laying behavior extends a few hundred meters around any given trap. However, when the temporal variability of the egg count data was incorporated into the analysis, no single optimal buffer size could be identified, and the effect of breeding site abundance lost statistical significance. The researchers caution that the noisy, seasonally fluctuating nature of ovitrap data limits how precisely the spatial drivers of egg laying can be pinned down, and that the maximum-count approach, while informative, should be complemented by temporal modeling in future studies.

For mosquito control programs, the practical implications are considerable. Because terraced house plots are positively associated with both breeding site abundance and ovitrap egg counts, control measures could be prioritized in neighborhoods dominated by this building type to increase efficiency. In an era when municipal budgets for invasive species management are under pressure, being able to direct inspections, larvicide applications and community engagement toward the most productive habitats represents a meaningful gain in cost effectiveness. Rather than treating every parcel equally, authorities can use building structure, a feature already mapped in most European cities, as a rapid proxy for risk.

More broadly, the study highlights how the built environment itself functions as ecological infrastructure for invasive species. As Aedes albopictus continues its northward expansion in a warming climate, the interplay between housing form, human behavior and vector biology will increasingly determine which streets and courtyards become mosquito strongholds. The Heidelberg findings provide a template that other cities in Germany and beyond could adapt, combining parcel-level breeding site records with trap surveillance and spatial modeling to design smarter, more targeted control campaigns against one of the world’s most successful urban invaders.

Subject of Research: Effects of urban building structure on breeding site distribution and ovitrap egg counts of the invasive mosquito Aedes albopictus in Heidelberg, Germany

Article Title: Effects of urban building structures on the distribution of breeding sites and ovitrap egg counts of Aedes albopictus in Pfaffengrund, Heidelberg, Germany

Article References: Wahl, C., Lautenbach, S., Tokatlian Rodríguez, A., & Becker, N. (2026). Effects of urban building structures on the distribution of breeding sites and ovitrap egg counts of Aedes albopictus in Pfaffengrund, Heidelberg, Germany. Parasites & Vectors, 19(1), Article 393. https://doi.org/10.1186/s13071-026-07655-z

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07655-z

Keywords: Aedes albopictus, Asian tiger mosquito, invasive species, mosquito control, urban ecology, breeding sites, ovitraps, terraced houses, vector-borne disease, Germany, urban structure, egg counts