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Over the past two decades efforts to control malaria have halved the number of cases globally, yet burdens remain high in much of Africa and the elimination of malaria has not been achieved even in areas where extreme reductions have been sustained, such as South Africa 1 , 2 . Studies seeking to understand the paradoxical persistence of malaria in areas in which surface water is absent for 3–8 months of the year have suggested that some species of Anopheles mosquito use long-distance migration 3 . Here we confirm this hypothesis through aerial sampling of mosquitoes at 40–290 m above ground level and provide—to our knowledge—the first evidence of windborne migration of African malaria vectors, and consequently of the pathogens that they transmit. Ten species, including the primary malaria vector Anopheles coluzzii , were identified among 235 anopheline mosquitoes that were captured during 617 nocturnal aerial collections in the Sahel of Mali. Notably, females accounted for more than 80% of all of the mosquitoes that we collected. Of these, 90% had taken a blood meal before their migration, which implies that pathogens are probably transported over long distances by migrating females. The likelihood of capturing Anopheles species increased with altitude (the height of the sampling panel above ground level) and during the wet seasons, but variation between years and localities was minimal. Simulated trajectories of mosquito flights indicated that there would be mean nightly displacements of up to 300 km for 9-h flight durations. Annually, the estimated numbers of mosquitoes at altitude that cross a 100-km line perpendicular to the prevailing wind direction included 81,000  Anopheles gambiae sensu stricto, 6 million A. coluzzii and 44 million Anopheles squamosus . These results provide compelling evidence that millions of malaria vectors that have previously fed on blood frequently migrate over hundreds of kilometres, and thus almost certainly spread malaria over these distances. The successful elimination of malaria may therefore depend on whether the sources of migrant vectors can be identified and controlled. Aerial sampling in the Sahel of Mali reveals large numbers of windborne malaria mosquitoes that had recently fed on blood and could cover hundreds of kilometres in a single night.

Mosquitoes track odors, locate hosts, and find mates visually. The color of a food resource, such as a flower or warm-blooded host, can be dominated by long wavelengths of the visible light spectrum (green to red for humans) and is likely important for object recognition and localization. However, little is known about the hues that attract mosquitoes or how odor affects mosquito visual search behaviors. We use a real-time 3D tracking system and wind tunnel that allows careful control of the olfactory and visual environment to quantify the behavior of more than 1.3 million mosquito trajectories. We find that CO 2 induces a strong attraction to specific spectral bands, including those that humans perceive as cyan, orange, and red. Sensitivity to orange and red correlates with mosquitoes’ strong attraction to the color spectrum of human skin, which is dominated by these wavelengths. The attraction is eliminated by filtering the orange and red bands from the skin color spectrum and by introducing mutations targeting specific long-wavelength opsins or CO 2 detection. Collectively, our results show that odor is critical for mosquitoes’ wavelength preferences and that the mosquito visual system is a promising target for inhibiting their attraction to human hosts. Vision in mosquitoes plays a critical but understudied role in their attraction to hosts. Here, the authors show that encounter with an attractive odor gates the mosquito attraction to specific colors, especially the long wavelengths reflected from human skin. Filtering the long wavelengths reflected from the human skin or knocking-out the ability for the mosquito to detect the wavelengths, suppressed their attraction. This work transforms our understanding of mosquito vision from the conventional view that vision does little in mediating mosquito-host interactions, to the recognition that vision plays a critical role.

Malaria transmission is known to be strongly impacted by temperature. The current understanding of how temperature affects mosquito and parasite life history traits derives from a limited number of empirical studies. These studies, some dating back to the early part of last century, are often poorly controlled, have limited replication, explore a narrow range of temperatures, and use a mixture of parasite and mosquito species. Here, we use a single pairing of the Asian mosquito vector, An. stephensi and the human malaria parasite, P. falciparum to conduct a comprehensive evaluation of the thermal performance curves of a range of mosquito and parasite traits relevant to transmission. We show that biting rate, adult mortality rate, parasite development rate, and vector competence are temperature sensitive. Importantly, we find qualitative and quantitative differences to the assumed temperature-dependent relationships. To explore the overall implications of temperature for transmission, we first use a standard model of relative vectorial capacity. This approach suggests a temperature optimum for transmission of 29°C, with minimum and maximum temperatures of 12°C and 38°C, respectively. However, the robustness of the vectorial capacity approach is challenged by the fact that the empirical data violate several of the model's simplifying assumptions. Accordingly, we present an alternative model of relative force of infection that better captures the observed biology of the vector-parasite interaction. This model suggests a temperature optimum for transmission of 26°C, with a minimum and maximum of 17°C and 35°C, respectively. The differences between the models lead to potentially divergent predictions for the potential impacts of current and future climate change on malaria transmission. The study provides a framework for more detailed, system-specific studies that are essential to develop an improved understanding on the effects of temperature on malaria transmission.

Since its initial isolation in Uganda in 1937 through the present, West Nile virus (WNV) has become an important cause of human and animal disease worldwide. WNV, an enveloped virus of the genus Flavivirus, is naturally maintained in an enzootic cycle between birds and mosquitoes, with occasional epizootic spillover causing disease in humans and horses. The mosquito vectors for WNV are widely distributed worldwide, and the known geographic range of WNV transmission and disease has continued to increase over the past 77 years. While most human infections with WNV are asymptomatic, severe neurological disease may develop resulting in long-term sequelae or death. Surveillance and preventive measures are an ongoing need to reduce the public health impact of WNV in areas with the potential for transmission.

Dirofilaria repens is a nematode affecting domestic and wild canids, transmitted by several species of mosquitoes. It usually causes a non-pathogenic subcutaneous infection in dogs and is the principal agent of human dirofilariosis in the Old World. In the last decades, D. repens has increased in prevalence in areas where it has already been reported and its distribution range has expanded into new areas of Europe, representing a paradigmatic example of an emergent pathogen. Despite its emergence and zoonotic impact, D. repens has received less attention by scientists compared to Dirofilaria immitis . In this review we report the recent advances of D. repens infection in dogs and humans, and transmission by vectors, and discuss possible factors that influence the spread and increase of this zoonotic parasite in Europe. There is evidence that D. repens has spread faster than D. immitis from the endemic areas of southern Europe to northern Europe. Climate change affecting mosquito vectors and the facilitation of pet travel seem to have contributed to this expansion; however, in the authors’ opinion, the major factor is likely the rate of undiagnosed dogs continuing to perpetuate the life-cycle of D. repens . Many infected dogs remain undetected due to the subclinical nature of the disease, the lack of rapid and reliable diagnostic tools and the poor knowledge and still low awareness of D. repens in non-endemic areas. Improved diagnostic tools are warranted to bring D. repens diagnosis to the state of D. immitis diagnosis, as well as improved screening of imported dogs and promotion of preventative measures among veterinarians and dog owners. For vector-borne diseases involving pets, veterinarians play a significant role in prevention and should be more aware of their responsibility in reducing the impact of the zoonotic agents. In addition, they should enhance multisectorial collaboration with medical entomologists and the public health experts, under the concept and the actions of One Health-One Medicine.

Mosquitoes collected from mid-December 2020 to early March 2021 from hibernacula in northeastern Germany, a region of West Nile virus (WNV) activity since 2018, were examined for WNV-RNA. Among the 6101 mosquitoes tested in 722 pools of up to 12 specimens, one pool of 10 Culex pipiens complex mosquitoes collected in early March 2021 in the cellar of a medieval castle in Rosslau, federal state of Saxony-Anhalt, tested positive. Subsequent mosquito DNA analysis produced Culex pipiens biotype pipiens. The pool homogenate remaining after nucleic acid extraction failed to grow the virus on Vero and C6/36 cells. Sequencing of the viral NS2B-NS3 coding region, however, demonstrated high homology with virus strains previously collected in Germany, e.g., from humans, birds, and mosquitoes, which have been designated the East German WNV clade. The finding confirms the expectation that WNV can overwinter in mosquitoes in Germany, facilitating an early start to the natural transmission season in the subsequent year. On the other hand, the calculated low infection prevalence of 0.016–0.20%, depending on whether one or twelve of the mosquitoes in the positive pool was/were infected, indicates a slow epidemic progress and mirrors the still-hypoendemic situation in Germany. In any case, local overwintering of the virus in mosquitoes suggests its long-term persistence and an enduring public health issue.

Female mosquitoes require a blood meal for reproduction, and this blood meal provides the underlying mechanism for the spread of many important vector-borne diseases in humans. A deeper understanding of the molecular mechanisms linked to mosquito blood meal processes and reproductive events is of particular importance for devising innovative vector control strategies. We found that the conserved microRNA miR-8 is an essential regulator of mosquito reproductive events. Two strategies to inhibit miR-8 function in vivo were used for functional characterization: systemic antagomir depletion and spatiotemporal inhibition using the miRNA sponge transgenic method in combination with the yeast transcriptional activator gal4 protein/upstream activating sequence system. Depletion of miR-8 in the female mosquito results in defects related to egg development and deposition. We used a multialgorithm approach for miRNA target prediction in mosquito 3′ UTRs and experimentally verified secreted wingless-interacting molecule ( swim ) as an authentic target of miR-8. Our findings demonstrate that miR-8 controls the activity of the long-range Wingless (Wg) signaling by regulating Swim expression in the female fat body. We discovered that the miR-8/Wg axis is critical for the proper secretion of lipophorin and vitellogenin by the fat body and subsequent accumulation of these yolk protein precursors by developing oocytes. Significance Mosquitoes transmit some of the most devastating human diseases. Acquisition of blood initiates a cascade of events in various tissues in the female mosquito. Here we describe our study using newly established genetic tools in mosquito biology and a comprehensive microRNA target identification analysis to characterize microRNA-8 (miR-8) functionally in Aedes aegypti female mosquitoes. miR-8 works in the fat body by regulating its target, secreted wingless-interacting molecule . miR-8 acts on the long-range Wingless signaling pathway and plays an essential role in the female mosquito fat body controlling the secretory activity of yolk protein precursors required for oocyte development. Thus, this study identifies the fat body specific action of miR-8 and its target in regulating mosquito reproduction.

Hearing is essential for the courtship of one of the major carriers of human disease, the mosquito. Males locate females through flight-tone recognition and both sexes engage in mid-air acoustic communications, which can take place within swarms containing thousands of individuals. Despite the importance of hearing for mosquitoes, its mechanisms are still largely unclear. We here report a multilevel analysis of auditory function across three disease-transmitting mosquitoes ( Aedes aegypti , Anopheles gambiae and Culex quinquefasciatus ). All ears tested display transduction-dependent power gain. Quantitative analyses of mechanotransducer function reveal sex-specific and species-specific variations, including male-specific, highly sensitive transducer populations. Systemic blocks of neurotransmission result in large-amplitude oscillations only in male flagellar receivers, indicating sexually dimorphic auditory gain control mechanisms. Our findings identify modifications of auditory function as a key feature in mosquito evolution. We propose that intra-swarm communication has been a driving force behind the observed sex-specific and species-specific diversity. Auditory processing is an important component of mosquito behaviour including mating. Here the authors demonstrate substantial sex- and also species-specific variation in mosquito auditory transduction, amplification and gain control.

Mosquitoes are a widely diverse group of organisms, comprising ∼3,500 species that live in an enormous range of habitats. Some species are vectors of diseases that afflict hundreds of millions of people each year. Although understanding of mosquito olfaction has progressed dramatically in recent years, mosquito taste remains greatly understudied. Since taste is essential to feeding, egg laying, and mating decisions in insects, improved understanding of taste in mosquitoes could provide new mechanistic insight into many aspects of their behavior. We provide a guide to current knowledge in the field, and we suggest a wealth of opportunities for research that are now enabled by recent scientific and technological advances. We also propose means by which taste might be exploited in new strategies for mosquito control, which may be urgently needed as the geographical ranges of vector species increase with climate change.

Surprisingly, previous studies that have investigated the vector competence for Zika virus have neglected other mosquito species,7-9 such as Culex species, which are very abundant in the tropical areas where Zika virus has spread and have also transmitted arboviruses that are closely related to Zika virus, such as West Nile virus. To assume that the main vector is A aegypti in areas in which other mosquito species coexist is naive, and could be catastrophic if other species are found to have important roles in Zika virus transmission. [...]researchers from different institutions who are working on vector-pathogen interactions must attempt to answer this important question as soon as possible, to direct control actions towards the correct target and to help to minimise the drastic effects of Zika virus disease outbreaks.