The scale of the problem is difficult to overstate. Across the world, there are close to 300 million cases of malaria and almost 400 million dengue infections every year. Malaria is a serious, life-threatening disease caused by a parasite that is typically spread to humans through the bites of infected female Anopheles mosquitoes. Dengue, by contrast, is caused by a virus transmitted through the bites of infected female Aedes mosquitoes. The two diseases share a vector-borne mode of transmission but differ profoundly in their biology, their geography and, as the review makes clear, their recent trajectories.

Lead researcher Dr Toby Cumming, a research fellow in the Health and Climate Initiative at the Monash School of Public Health and Preventive Medicine, said properly understanding the drivers of disease transmission is key to identifying effective public health responses. The review, he argued, is an attempt to untangle the complex web of conditions, climatic and otherwise, that determine where mosquitoes thrive, where parasites and viruses circulate, and where human populations are exposed.

The climatic logic is straightforward in outline, even if it is complicated in detail. As climate change increases temperatures and alters rainfall patterns, this expands the areas with climatic conditions in which Anopheles and Aedes mosquito populations can thrive, Dr Cumming said. Temperature influences every stage of a mosquito’s life cycle, from the speed of larval development to adult survival, and it also governs the rate at which pathogens mature inside the insect. Warmer conditions can shorten the extrinsic incubation period of a virus or parasite, meaning a mosquito that picks up an infection becomes infectious sooner and is more likely to pass it on before it dies. Rainfall, meanwhile, determines the availability of the standing water in which mosquitoes breed, although the relationship is far from simple, since drought can concentrate breeding sites and heavy rain can flush them away.

Those complications matter, and the researchers are careful to emphasise them. The influence of climate factors on transmission is non-linear, effects are seasonal, and there is substantial local variability, meaning that a single global projection can obscure sharply different outcomes from one valley, city or country to the next. Yet despite this complexity, the review notes that warming and shifting rainfall have broadly similar impacts on malaria and dengue transmission, pushing both diseases into regions where they were previously rare or absent and intensifying transmission where conditions are already favourable.

Here the story takes a turn that the authors describe as crucial for policy. Over the last century, during a time of unambiguous warming, rates of malaria have declined while rates of dengue have risen, Dr Cumming said. If climate were the only force at work, such divergence would be hard to explain. The fact that it occurred anyway tells us something important: human interventions and human settlement patterns can overwhelm, redirect or amplify climatic signals, sometimes in opposite directions for two diseases carried by related insects.

The review highlights the non-climate factors that help explain these different trajectories. Mosquito control interventions and drug therapies have driven major gains in reducing malaria transmission. Insecticide-treated bed nets, indoor residual spraying, artemisinin-based combination therapies and rapid diagnostic tests have, over decades, pushed malaria out of large parts of the world where it once flourished, including much of Europe and North America. Dengue has enjoyed no such success. Increasing urbanisation has favoured Aedes mosquitoes, which breed in small man-made containers, thrive in dense tropical cities and bite during the day, and hence the spread of dengue, for which no therapeutics are available. Treatment for dengue is largely supportive, which means that prevention, rather than cure, carries the full weight of controlling the disease.

Dr Cumming emphasised that there is no room for complacency on the malaria front either. Although malaria is in long-term decline, global incidence has risen 8.5 per cent over the past decade, a reversal that coincides with challenges including funding shortfalls, drug and insecticide resistance, conflict and displacement in endemic regions. Recent malaria trends and the rapid growth in dengue are both serious concerns, and we must escalate our prevention and control efforts, he said. The warning is that gains built over a century can erode quickly, particularly as climate change expands the climatic envelope in which transmission is possible.

Against this backdrop, novel preventive interventions for dengue are emerging. Vaccines are now part of the toolkit, and innovative vector control strategies are showing promise, most notably the introduction of the bacterium Wolbachia into Aedes mosquito populations. Wolbachia reduces the mosquitoes’ ability to transmit dengue, and the strategy has been developed by the World Mosquito Program, a not-for-profit group of companies owned by Monash University. When Wolbachia-carrying males and females establish themselves in a wild population, they pass the bacterium to their offspring, and the virus-blocking effect spreads with them, offering a self-sustaining form of biological control that does not depend on repeated insecticide application. Such approaches, combined with the gradual arrival of dengue vaccines, mark a shift in the epidemiology of a disease that has long outpaced medical countermeasures.

Ultimately, the research reinforces the need for a coordinated approach, encompassing interventions to address the many climate and non-climate factors that contribute to the spread of mosquito-borne disease, Dr Cumming said. That coordination spans several domains at once: sustained vector control and surveillance, deployment of vaccines and drugs where they exist, urban planning and water management that reduce Aedes breeding habitat, and, at the global scale, cutting greenhouse gas emissions to limit the warming that is steadily redrawing the map of mosquito-borne risk. The review’s implicit conclusion is that climate change is not a sentence of inevitable escalation. The century of divergence between malaria and dengue demonstrates that human action, whether through bed nets and medicines or through unplanned urban growth, can shape disease outcomes as powerfully as any weather pattern. The task now, the authors argue, is to apply that lesson deliberately, before the combined pressures of warming temperatures, expanding mosquito ranges and growing urban populations tip the balance the other way.

Subject of Research: Climate change impacts on malaria and dengue transmission and prevention strategies

Article Title: Itching for a solution: Addressing mosquito-borne disease as climate change bites

Article References: Itching for a solution: Addressing mosquito-borne disease as climate change bites. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: malaria, dengue, climate change, mosquito-borne disease, vector control, Wolbachia, Aedes, Anopheles, vaccines, urbanisation, public health, Science Advances

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 research, led by Kylee R. Noel and colleagues at the University of Illinois Urbana-Champaign and the Illinois Natural History Survey, set out to answer a question that has received surprisingly little rigorous experimental attention. Insecticides applied to agricultural fields, suburban lawns, and mosquito control zones inevitably find their way into surface waters, where concentrations rarely reach levels that kill mosquito larvae outright. Yet these sublethal concentrations can still perturb larval physiology, development, and behavior. Because many of the traits that determine how efficiently a mosquito transmits a virus — adult survival, fecundity, and vector competence — are shaped during the aquatic juvenile stages, the researchers hypothesized that early-life insecticide exposure could leave a lasting imprint on transmission potential.

To test this, the team reared Culex pipiens larvae under standard insectary conditions, with temperatures maintained at approximately 27.6 degrees Celsius, relative humidity around 70 percent, and a photoperiod of 16 hours of light and 8 hours of darkness. One group of larvae was exposed to a sublethal concentration of permethrin, a widely used synthetic pyrethroid insecticide, at 0.01 milligrams per liter — a dose low enough not to cause mortality but high enough to exert physiological stress. Upon eclosion, adult mosquitoes from both the exposed and unexposed control groups were transferred into environmental chambers held at either 25 or 29 degrees Celsius, two temperatures within the range that Culex pipiens routinely experiences during the summer transmission season in the American Midwest.

The experimental design is notable because it separates the larval and adult environments, allowing the investigators to disentangle effects that occur during development from those imposed on the adult stage. Mosquitoes infected with West Nile virus were then monitored across the key parameters that together constitute vectorial capacity, the epidemiological framework used to estimate how effectively a vector population can transmit a pathogen. These parameters include adult survival, which determines how long a female lives and therefore how many blood meals she can take; fecundity, which influences population growth; and vector competence, a composite measure encompassing infection rate, dissemination rate from the midgut to other tissues, and the ability to transmit virus in saliva during a subsequent bite.

The life-history results revealed that permethrin exposure during the larval stage slowed development: exposed larvae took longer to mature into adults than untreated controls. More strikingly, the adult females that emerged from treated larvae survived longer than their control counterparts. Extended adult longevity is a critical variable in vectorial capacity, because the extrinsic incubation period of West Nile virus — the time it takes for an infected mosquito to become infectious — must be shorter than the mosquito’s lifespan for transmission to occur. Females that live longer have a greater probability of surviving that incubation window and biting another host while infectious, effectively multiplying their contribution to the transmission cycle.

Temperature exerted its own powerful influence on the virological side of the equation. At 29 degrees Celsius, mosquitoes showed higher infection and dissemination rates, and viral RNA was detected at greater levels within mosquito tissues, compared with the cooler 25 degree environment. This pattern is consistent with a broader literature showing that warmer temperatures accelerate viral replication within mosquito vectors, shortening the extrinsic incubation period and pushing mosquitoes to infectious status sooner after an infective blood meal. However, the study’s most consequential finding emerged when the two stressors were analyzed together rather than in isolation.

At 29 degrees Celsius, the control mosquitoes — those with no larval insecticide exposure — exhibited the lowest transmission potential of any group in the experiment. By contrast, mosquitoes that had been exposed to permethrin as larvae displayed markedly higher transmission potential under the same warm conditions. This interaction indicates that sublethal pesticide exposure and elevated temperature do not simply add their effects; they combine in a non-additive manner that reshapes the overall transmission equation. A warmer world, in other words, may not uniformly increase West Nile virus risk — the outcome depends on what the vector population experienced during its aquatic development, and urban or agricultural waters contaminated with pyrethroid residues could tip the balance toward greater transmission.

Why would larval chemical stress enhance transmission potential at high temperatures while control mosquitoes fared worse? The authors’ data suggest that the combination of extended adult survival in permethrin-exposed females and temperature-driven gains in infection and dissemination rates produced a population of longer-lived, more competent vectors precisely under the conditions where unexposed mosquitoes performed least well. The physiological mechanisms linking larval permethrin exposure to adult longevity and vector competence were not fully resolved in this experiment, but stress-induced changes in larval metabolism, immune priming, or resource allocation could plausibly alter adult physiology in ways that interact with viral kinetics at elevated temperatures. Further mechanistic work will be needed to pin down these pathways, and the authors note that their experiment used a single permethrin concentration and two adult temperatures, leaving open questions about dose-response relationships and the full thermal range experienced in the field.

The public health and environmental implications are substantial. Mosquito abatement districts routinely apply pyrethroids as larvicides and adulticides, and agricultural runoff delivers additional residues into stormwater ponds, drainage ditches, and other habitats where Culex pipiens breeds. If those residues leave surviving larvae physiologically primed for greater transmission as adults — particularly during heat waves, when West Nile virus epidemics historically peak — then conventional insecticide use could carry an unrecognized trade-off: suppressing mosquito abundance in the short term while inadvertently enhancing the transmission efficiency of the mosquitoes that survive. The study therefore argues for integrated surveillance that monitors not just mosquito numbers but the chemical and thermal conditions of larval habitats, especially in environments exposed to rising temperatures driven by climate change.

As with all laboratory studies, translating these results to real-world epidemics will require field validation, since wild mosquito populations encounter fluctuating temperatures, heterogeneous insecticide mixtures, and competing larval stresses that a controlled chamber experiment cannot fully replicate. Nevertheless, the work provides a clear experimental demonstration that the developmental environment of a disease vector can rewrite the rules of transmission established by adult conditions alone. For a virus like West Nile, whose seasonal dynamics depend on a delicate interplay between vectors, hosts, and climate, understanding these cross-generational and cross-stressor interactions may prove essential for predicting and preventing the outbreaks of the future. The research was supported by the State of Illinois Used Tire Management and Emergency Public Health funds and by a grant from the University of Illinois Center for Advanced Climate Solutions.

Subject of Research: Interaction of sublethal insecticide exposure and temperature on West Nile virus transmission by Culex pipiens mosquitoes

Article Title: Sublethal insecticide exposure and temperature interact to shape West Nile virus transmission potential of Culex pipiens

Article References: Sublethal insecticide exposure and temperature interact to shape West Nile virus transmission potential of Culex pipiens. (n.d.). https://doi.org/10.1186/s13071-026-07700-x

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07700-x

Keywords: West Nile virus, Culex pipiens, permethrin, sublethal exposure, vector competence, vectorial capacity, temperature, insecticide pollution, mosquito-borne disease, Parasites & Vectors, life history traits, climate change