Mosquito Feeding Research Articles

The food of life: which nectar do mosquitoes feed on?-An evidence-based meta-analysis.

Nectar is an important source of food for adult mosquitoes, influencing their biological characteristics including longevity, fecundity, and flight range. Consequently, it can impact mosquitoes' survival and efficiency in transmitting disease. Different mosquito species are known to show preferences for flower nectar from certain plants, yet despite the importance of these plant-mosquito associations, knowledge of such biotic interactions is sparse. Here, we present a systematic map to address the question: "Which nectar do mosquitoes feed on?." The mapping process identified 49 articles (comprising 51 studies) meeting inclusion criteria, detailing 397 records of 74 mosquito species feeding on nectar from 145 plant species and 109 genera. Data extracted from the map were then analyzed to better understand if mosquitoes showed preferences for specific plant nectar. A key finding from this study is clear evidence supporting the hypothesis that mosquitoes exhibit preferences for nectar from particular plant species, including 77 species of plants and 58 genera for Aedes species, 18 species of plants and 17 genera for Anopheles species, and 16 species of plants and 16 genera for Culex species (all 3 genera belong in Diptera: Culicidae). Our study also highlighted the need for further field and laboratory work in time and space and using methods that randomly selects plant species for investigation. This would facilitate a better understanding of the relationship between mosquito feeding behavior and nectar seasonality and abundance; data that are critical for the development and improvement of new mosquito control methods to tackle vector-borne diseases.

Evaluation of the transmission-blocking potential of Plasmodium vivax antigen Pvg37 using transgenic rodent parasites and clinical isolates

BackgroundPlasmodium vivax is a major cause of malaria, particularly outside Africa, necessitating effective strategies for public health management. Transmission-blocking vaccines (TBVs) have shown the potential to inhibit malaria transmission by targeting antigens expressed in sexual-stage parasites. Pbg37, a conserved protein expressed in sexual stages from gametocyte to ookinete in the rodent parasite P. berghei, is a viable target for TBV development.Methods and findingsIn this study, we constructed a transgenic strain, TrPvg37Pb, expressing Pvg37 using the P. berghei ΔPbg37 strain. Initial findings demonstrated that the replacement of Pbg37 with the exogenous Pvg37 did not impact parasite growth or development. Notably, Pvg37 was expressed during the gametocyte to ookinete development and was associated with the plasmic membrane, similar to Pbg37. To evaluate the potential of Pvg37 as a TBV candidate, we synthesized two Pvg37 polypeptides and immunized rabbits to generate antibodies. In vitro experiments demonstrated that anti-Pvg37-P2 antibodies significantly inhibited the formation of male gametes and ookinetes in the transgenic TrPvg37Pb parasite. Additionally, in mosquito feeding assays, mosquitos feeding on TrPvg37Pb-infected mice passively transferred with anti-Pvg37-P2 antibodies showed a significant 80.2% decrease in oocyst density compared to the control group. Furthermore, in direct membrane feeding experiments using four clinical P. vivax isolates, the anti-Pvg37 antibodies significantly reduced oocyst density by 28.6–50.4%.ConclusionPvg37 is a promising candidate for P. vivax TBV development, deserving further research and optimization to enhance its immunogenicity and transmission-blocking activity.

Meta-analyses of Culex blood-meals indicates strong regional effect on feeding patterns.

Understanding host utilization by mosquito vectors is essential to assess the risk of vector-borne diseases. Many studies have investigated the feeding patterns of Culex mosquitoes by molecular analysis of blood-meals from field collected mosquitoes. However, these individual small-scale studies only provide a limited understanding of the complex host-vector interactions when considered in isolation. Here, we analyse the Culex blood-feeding data from 109 publications over the last 15 years to provide a global insight into the feeding patterns of Culex mosquitoes, with particular reference to vectors of currently emerging Culex-borne viruses such as West Nile and Usutu. Data on 29990 blood-meals from 70 different Culex species were extracted from published literature. The percentage of blood-meals on amphibian, avian, human, non-human mammalian, and reptilian hosts was determined for each Culex species. Our analysis showed that feeding patterns were not significantly explained by mosquito species-level phylogeny, indicating that external factors play an important role in determining mosquito feeding patterns. For Cx. quinquefasciatus, 'Cx. pipiens pooled', and Cx. tritaeniorhynchus, feeding patterns were compared across the world's seven biogeographical realms. Culex tritaeniorhynchus, 'Cx. pipiens pooled' and Cx. quinquefasciatus all had significantly varied feeding patterns between realms. These results demonstrate that feeding patterns of Culex mosquitoes vary between species but can also vary between geographically distinct populations of the same species, indicating that regional or population-level adaptations are major drivers of host utilization. Ultimately, these findings support the surveillance of vector-borne diseases by specifying which host groups are most likely to be at risk.

Contrasting vector competence of three main East African Anopheles malaria vector mosquitoes for Plasmodium falciparum

There are three Anopheles mosquito species in East Africa that are responsible for the majority of malaria transmission, posing a significant public health concern. Understanding the vector competence of different mosquito species is crucial for targeted and cost-effective malaria control strategies. This study investigated the vector competence of laboratory reared strains of East African An. gambiae sensu stricto, An. funestus s.s., and An. arabiensis mosquitoes towards local isolates of Plasmodium falciparum infection. Mosquito feeding assays using gametocytaemic blood from local donors revealed significant differences in both prevalence and intensity of oocyst and sporozoite infections among the three vectors. An. funestus mosquitoes presented the highest sporozoite prevalence 23.5% (95% confidence interval (CI) 17.5–29.6) and intensity of infection 6-58138 sporozoites. Relative to An. funestus, the odds ratio for sporozoites prevalence were 0.46 (95% CI 0.25–0.85) in An. gambiae and 0.19 (95% CI 0.07–0.51) in An. arabiensis, while the incidence rate ratio for sporozoite intensity was 0.31 (95% CI 0.14–0.69) in An. gambiae and 0.66 (95% CI 0.16–2.60) in An. arabiensis. Our findings indicate that all three malaria vector species may contribute to malaria transmission in East Africa, with An. funestus demonstrating superior vector competence. In conclusion, there is a need for comprehensive malaria control strategies targeting major malaria vector species, an update of malaria transmission models to consider vector competence and evaluation of malaria transmission blocking interventions in assays that include An. funestus mosquitoes.

Transmission of transgenic mosquito-killing fungi during copulation

Entomopathogenic fungi engineered to express insect-specific neurotoxins have demonstrated potential as microbial control agents against malaria mosquitoes. Currently, the primary application method is via direct contact of spores with indoor resting mosquitoes. However, many malaria-transmitting mosquitoes feed and rest outdoors. To target these, we have developed an alternative application method that exploits the lethality of transgenic fungi as a sexually transmitted mosquito disease. This approach has both a wider interdisciplinary significance and important implications for preventing mosquito-borne diseases.

Unraveling the Molecular Mechanisms of Mosquito Salivary Proteins: New Frontiers in Disease Transmission and Control.

Mosquito-borne diseases are a group of illnesses caused by pathogens transmitted by mosquitoes, and they are globally prevalent, particularly in tropical and subtropical regions. Pathogen transmission occurs during mosquito blood feeding, a process in which mosquito saliva plays a crucial role. Mosquito saliva contains a variety of biologically active proteins that facilitate blood feeding by preventing blood clotting, promoting vasodilation, and modulating the host's immune and inflammatory responses. These effects create an environment conducive to pathogen invasion and dissemination. Specific mosquito salivary proteins (MSPs) can promote pathogen transmission through mechanisms that either regulate hosts' anti-infective immune responses or directly enhance pathogens' activity. Strategies targeting these MSPs have emerged as an innovative and promising approach for the control of mosquito-borne diseases. Meanwhile, the diversity of these proteins and their complex interactions with the host immune system necessitate further research to develop safer and more effective interventions. This review examines the functional diversity of MSPs and their roles in disease transmission, discusses the advantages and challenges of strategies targeting these proteins, and explores potential future directions for research in this area.

Comparative efficacy of Vector Guard® to Olyset® Plus insecticide-treated nets against strongly pyrethroid-resistant Anopheles arabiensis in experimental huts in Tanzania

IntroductionThe resistance of malaria vectors to pyrethroids has compromised the efficacy of pyrethroid insecticide-treated nets (ITNs). In response, ITNs with pyrethroids and piperonyl butoxide (PBO) synergists were developed to overcome metabolic pyrethroid resistance mechanisms. One such net is Vector Guard®. To demonstrate its potential efficacy for public health use, a comparative efficacy study was conducted to evaluate Vector Guard® relative to Olyset® Plus (a pyrethroid–PBO ITN proven to reduce malaria transmission more effectively than pyrethroid ITNs) and Royal® Sentry 2.0 (a pyrethroid-only ITN included to demonstrate the added benefit of PBO) in experimental huts in Tanzania.MethodsAn experimental hut trial using two blocks of a 7 × 7 Latin square design was conducted over seven rounds (49 experimental nights). Treatments were rotated at the end of each round, and volunteers were rotated nightly within one block. Both unwashed and 20× washed nets of each type were evaluated, alongside an untreated net used as a negative control. The primary endpoint was the proportion of Anopheles arabiensis that died within 24 h, and the secondary endpoint was the proportion of blood feeding. Data were analyzed using binomial logistic regression with fixed effects using a 7% non-inferiority margin.ResultsThe pooled results showed that Vector Guard® was non-inferior and was superior to Olyset® Plus, with higher mortality for Vector Guard® [28% vs. 18%; odds ratio (OR) = 1.93, 95%CI = 1.81–2.06]. Both pyrethroid–PBO nets were superior to Royal Sentry® 2.0 (p < 0.001) in terms of mosquito mortality. For the secondary blood feeding endpoint, Vector Guard® was also found to be non-inferior to Olyset® Plus (0.6% vs. 0.2%; OR = 2.37, 95%CI = 1.77–3.17). Vector Guard® showed similar efficacy to Royal Sentry® 2.0 in reducing the proportion of mosquito blood feeding (0.6% vs. 0.6%; OR = 0.85, 95%CI = 0.68–1.07, p = 0.161).ConclusionVector Guard® demonstrated superior mosquito mortality compared with both Olyset® Plus and Royal Sentry® 2.0, indicating that Vector Guard® is another promising pyrethroid–PBO ITN for the control of resistant malaria vectors. The addition of Vector Guard® to the class of pyrethroid–PBO ITNs will enable malaria control programs to select cost-effective ITNs, improving access to effective protection from malaria transmitted by resistant vectors.

Simplified Plasmodium falciparum membrane feeding assay using small Petri dishes and gel warmers

Studies on Plasmodium falciparum transmission require blood-feeding infectious gametocytes to mosquitoes using standard membrane-feeding assays (SMFAs). SMFAs are routinely performed using electric heating coils or glass membrane feeders connected to a circulatory water bath using tubing and clamps. Each of these approaches is expensive and requires a complex setup, hence restricting the number of assays that can be performed simultaneously. Furthermore, existing methods cannot be easily applied in low-resource field settings. This study presents a low-cost and simplified method for feeding mosquitoes with an infectious blood meal using 35 mm Petri dishes where temperature is maintained by using reusable gel warmers. The intensity and prevalence of infection in mosquitoes (Anopheles stephensi and Anopheles gambiae) fed via a Petri dish overlaid with gel warmers were comparable to mosquitoes fed using standard glass membrane feeders. The methodology described here can be easily applied in low-resource and field settings due to its low cost, ease of set up, and use of easily available supplies, such as Petri dishes, and reusable gel warmers. We believe a wide range of laboratories can easily adapt this method for P. falciparum transmission studies.

Impact of Climatic Factors on the Temporal Trend of Malaria in India from 1961 to 2021.

Malaria remains a significant public health problem in India. Although temperature influences Anopheline mosquito feeding intervals, population density, and longevity, the reproductive potential of the Plasmodium parasite and rainfall influence the availability of larval habitats, and evidence to correlate the impact of climatic factors on the incidence of malaria is sparse. Understanding the influence of climatic factors on malaria transmission will help us predict the future spread and intensification of the disease. The present study aimed to determine the impact of temporal trend of climatic factors such as annual average maximum, minimum, mean temperature, and rainfall on the annual incidence of malaria cases in India for a period of 61 years from 1961 to 2021 and relative humidity for a period of 41 years from 1981 to 2021. Two different analyses were performed. In the first analysis, the annual incidence of malaria and meteorological parameters such as annual maximum, minimum, and mean temperature, annual rainfall, and relative humidity were plotted separately in the graph to see if the temporal trend of climatic factors had any coherence or influence over the annual incidence of malaria cases. In the second analysis, a scatter plot was used to determine the relationship of the incidence of malaria in response to associated climatic factors. The incidence of malaria per million population was also calculated. In the first analysis, the annual malaria cases showed a negative correlation of varying degrees with relative humidity, minimum, maximum, and mean temperature, except rainfall, which showed a positive correlation. In the second analysis, the scatter plot showed that the rainfall had a positive correlation with malaria cases, and the rest of the climatic factors, such as temperature and humidity, had negative correlations of varying degrees. Out of the total 61 years studied, in 29 years, malaria cases increased more than 1000 square root counts when the minimum temperature was at 18-19 °C; counts also increased over a period of 33 years when the maximum temperature was 30-31 °C, over 37 years when the mean temperature was 24-25 °C, over 20 years when the rainfall was in the range of 100-120, and over a period of 29 years when the relative humidity was at 55-65%. While the rainfall showed a strong positive correlation with the annual incidence of malaria cases, the temperature and relative humidity showed negative correlations of various degrees. The increasing temperature may push the boundaries of malaria towards higher altitude and northern sub-tropical areas from the southern peninsular region. Although scanty rainfall reduces the transmission, increases in the same would increase the malaria incidence in India.

The effect of novel mosquito bite prevention tools on Anopheles minimus landing and key secondary endpoints: semi-field evaluations in Thailand

BackgroundThe Greater Mekong Subregion (GMS) aims to eliminate all human malaria by 2030 and is making substantial progress toward this goal, with malaria increasingly confined to forest foci. These transmission foci are predominantly inhabited by ethnic minorities, local populations, and rural mobile and migrant populations working in mining and agriculture. The recommendations of the World Health Organization (WHO) on malaria elimination states that small population groups which constitute a large proportion of the malaria transmission reservoir should benefit from targeted strategies to reduce transmission overall. These population groups are exposed to malaria vector bites during the day due to Anopheles daytime biting, and during the night, due to low bed net use and open sleeping structures. Such characteristics limit the effectiveness of the WHO core vector control strategies [indoor residual spraying (IRS), insecticide-treated nets (ITNs)], which target indoor resting and indoor feeding mosquitoes. Interventions that target daytime and outdoor resting or biting mosquitoes, and which complement IRS and ITNs and drug strategies, may hasten a decline in the malaria burden.MethodsThis study evaluated two transfluthrin- and one metofluthrin-based volatile pyrethroid spatial repellents (VPSRs), and etofenprox insecticide-treated clothing (ITC) with and without a topical repellent in a semi-field system (SFS) at two research sites in Thailand, across two trial rounds. The study estimated the protective efficacies of the vector control tools against two pyrethroid-susceptible Anopheles minimus strains in the form of 15 interventions, including a combined VPSR and ITC intervention. The interventions’ modes of action were studied by measuring their impact on mosquito landing, and on key life history traits known to affect vectoral capacity (knockdown, post-exposure blood feeding, and 24-h mortality) using a block-randomized crossover design. The odds ratio (OR) for each intervention compared to the control on each outcome was estimated.ResultsAll interventions substantially reduced An. minimus landings and prevented more than 50% mosquito landings when new (VPSRs) or unwashed (treated clothing). In addition to landing reduction, all interventions decreased post-exposure blood feeding, induced knockdown and increased mortality at 24 h. The VPSR interventions were generally more protective against landing than the treated clothing intervention. The combined intervention (VPSR + ITC) provided the greatest protection overall.ConclusionThis SFS evaluation indicates an effect of these VPSR and ITC interventions in reducing An. minimus landing for the user, and indicates their potential for community protection by secondary modes of action. This study demonstrates the utility of SFS trials in the evaluation of bite prevention tools and emphasizes the need for multiple evaluations at different sites. It also highlights possible sources of biases observed, including the measuring of mosquito landing rather than biting, weather parameters, and low mosquito recapture.

Use of Synthetic Membranes and Bovine Blood in Artificial Feeding Systems of Mosquitoes Improves Feeding Rates: Results from a Systematic Review and Meta-Analysis.

Artificial blood feeding of mosquitoes is essential for their rearing in insectaries as well as for mosquito-borne pathogen transmission experiments. We conducted a systematic review and meta-analysis of the different artificial feeding systems available for mosquitoes to synthesize evidence regarding their efficacy in terms of feeding rates and fecundity. PubMed, Scopus, Web of Science, and Google Scholar were systematically searched to retrieve 1,822 experimental studies assessing the efficacy of artificial feeding systems. After assessing eligibility and risk of bias, 25 studies were included in the final analysis. Studies were reviewed and meta-analysis was conducted using random-effects model. The primary outcomes were feeding rates and fecundity of mosquitoes belonging to genera Aedes, Culex, and Anopheles for the different systems. Subgroup analyses with respect to membrane, blood source, and mosquito genera were conducted. Sensitivity analysis was done to assess heterogeneity. The overall pooled estimate of feeding rate of mosquitoes and the average number of eggs laid per female mosquito using artificial blood-feeding systems were 72% (66-77%) and 71.9 (56.68-87.12), respectively. Results from this systematic review are suggestive of the advantages of novel techniques, such as Digital Thermo Mosquito Blood Feeder and 3D-printed feeders. The study provides evidence for improved feeding rates of mosquitoes in systems using bovine blood and synthetic membranes such as latex.

The Crucial Role of Additives in the Properties of Perlite- and Gypsum-Based Superabsorbent Composites I: The Development of Composite Carrier Materials for Biological Mosquito Larva-Killing Agents

The increase in the risks of mosquito-transmitted serious diseases or viral infections generates strong motivations to find new and efficient solutions for controlling blood-sucking mosquitoes. There are selective protein toxins such as BTI (Bacillus thüringiensis israelensis) used to kill mosquito larvae, which require carrier materials that keep the active ingredient on the surface of the water where the mosquito larvae feed. Environmentally friendly and effective composite carrier materials consisting of gypsum and perlite with controlled floating and sinking times were developed. The partial closing of open pores with modified cellulose derivatives as carboxymethyl cellulose (CMC) or cricket made from corn starch and hot water were used to ensure the slow dissolution of “CMC corks” in the pores, which can control the floating and sinking properties as well. The carrier composites were combined with BTI toxins such as 4% Vectobac WP (5000 ITU (international toxic unit)) toxin, resulting in a 90–100% killing rate against different tests (Culex pipiens) and various naturally abundant mosquito larva species. The stability test of the BTI-containing new carrier materials shows good applicability at flooded/dried/re-flooded areas where the flooding is temporary thus the composites can be applied as preventive treatment as well.

AC-DC Electropenetrography for the Study of Probing and Ingestion Behaviors of Culex tarsalis Mosquitoes on Human Hands.

Mosquitoes transmit pathogens that negatively affect human and animal health. A greater understanding of their blood-feeding biology and interactions with hosts and pathogens could be exploited to develop new targets for controlling mosquito-borne diseases. Unfortunately, probing (i.e., biting) behaviors of mosquitoes are poorly understood because they occur inside host tissues. Here, a non-invasive procedure is described for using AC-DC electropenetrography (EPG) to indirectly visualize and quantify mosquito feeding behaviors by recording changes in electrical signals generated when probing and ingesting on human hands. Thin gold wires are attached to the mosquitoes using conductive silver glue and connected to the EPG instrument. The human host holds a substrate voltage probe in their hand. Probing of the host by the wired mosquito completes the electrical circuit, and electrical signals are recorded on a computer as "waveforms" that can then be measured and enumerated for analysis. This methodology has been used to characterize the probing and ingestion behaviors of Aedes aegypti and Culex tarsalis mosquitoes and can be applied to other mosquito species. EPG can be used to study the effects of pathogens, insecticides, and other factors on mosquito feeding behaviors.

Fluralaner treatment of chickens kills the southern house mosquito, Culex quinquefasciatus.

The control of zoonotic and vector-borne pathogens is challenging due to the limited availability of intervention tools. West Nile virus (WNV) is an example of a globally distributed zoonotic arbovirus that circulates between Culex species (Diptera: Culicidae) mosquitoes and avian hosts, with spillover transmission to humans, resulting in disease cases. Interventions delivering systemic insecticides to vertebrate hosts used by vector species, known as xenointoxication, are potential tools for managing vector populations by creating toxic bloodmeals. In this study, we evaluated the impact of two systemic pesticides (ivermectin; Ivomec® Pour-On and fluralaner; Bravecto®), and one anthelmintic (fenbendazole; Safe-Guard® Aquasol) on the mortality of Cx. quinquefasciatus Say (Diptera: Culicidae). We found no significant difference in the feeding rates of mosquitoes that fed on treated chickens compared with those fed on untreated chickens, suggesting that the treatment did not repel mosquitoes. The mortality of Cx. quinquefasciatus mosquitoes feeding on fluralaner-treated chickens was significantly higher (p < 0.01) than those fed on control chickens at 3 and 7 days post-treatment, but this effect was not observed in mosquitoes fed on chickens treated with fenbendazole or ivermectin. No differences in mortality were observed among the groups at 14, 26 or 56 days post-treatment. These data support fluralaner as a xenointoxication tool to control Cx. quinquefasciatus populations and decrease the risk of human exposure to their associated pathogens.

Mitochondrial ATP synthesis is essential for efficient gametogenesis in Plasmodium falciparum

Plasmodium male and female gametocytes are the gatekeepers of human-to-mosquito transmission, therefore essential for propagation of malaria within a population. Whilst dormant in humans, their divergent roles during transmission become apparent soon after mosquito feeding with a rapid transformation into gametes – males forming eight motile sperm-like cells aiming to fertilise a single female gamete. Little is known about how the parasite fuels this abrupt change, and the potential role played by their large and elaborate cristate mitochondrion. Using a sex-specific antibody and functional mitochondrial labelling, we show that the male gametocyte mitochondrion is less active than that of female gametocytes and more sensitive to antimalarials targeting mitochondrial energy metabolism. Rather than a vestigial organelle discarded during male gametogenesis, we demonstrate that mitochondrial ATP synthesis is essential for its completion. Additionally, using a genetically encoded ratiometric ATP sensor, we show that gametocytes can maintain cytoplasmic ATP homeostasis in the absence of mitochondrial respiration, indicating the essentiality of the gametocyte mitochondrion for transmission alone. Together, this reveals how gametocytes responsively balance the conflicting demands of a dormant and active lifestyle, highlighting the mitochondria as a rich source of transmission-blocking targets for future drug development.

Extrinsic and intrinsic regulation of blood feeding in mosquitoes.

Mosquitoes obtain large amounts of blood from hosts in a short period of time. To efficiently obtain high-quality blood without being noticed by the host, mosquitoes sense external factors such as the taste of the host blood and the surrounding environment, and integrate these signals with their own internal information to determine whether to initiate blood feeding and how long to continue feeding. With the development of gene editing and behavior monitoring techniques, the factors that control blood feeding are being identified. Elucidating the factors that contribute to blood feeding is expected to provide new ideas for artificially controlling blood feeding, which has often been overlooked behind host attraction mechanisms. Furthermore, understanding salivary components, mechanisms controlling satiety in feeding, and differences between sugar feeding and blood feeding would help us understand how some mosquitoes have adopted and developed blood feeding over the course of evolution.

Only incandescent light significantly decreases feeding of Anopheles funestus s.s. (Diptera: Culicidae) mosquitoes under laboratory conditions

Recent work has demonstrated that exposure to artificial light at night (ALAN) may alter mosquito feeding behavior and so must be considered a moderator of vector-borne disease transfer. Anopheles funestus mosquitoes are a primary malaria vector in sub-Saharan Africa, but no study to date has tested the impact of ALAN on their feeding behavior. Here we test if the exposure to commonly used household lights (compact fluorescent lights, light-emitting diodes, and incandescent lights) alters Anopheles funestus feeding. Mated, unfed female mosquitoes were exposed to a light treatment, at the onset of darkness, followed by a blood-feeding assay. The light treatments consisted of a 30-min light pulse of one of the three household lights, each in individual experimental containers, versus controls. All three household lights resulted in a reduction in the percentage of females taking a blood meal, but only mosquitoes exposed to incandescent light showed a statistically significant reduction in feeding of 19.6% relative to controls which showed a 42.8% feeding rate. Our results suggest that exposure to some household lights during the night may have an immediate inhibitory effect on Anopheles funestus feeding. By helping identify which light types lead to a suppression of feeding, the findings of this study could provide insight necessary to design household lights that can help minimize mosquito feeding on humans.

Mosquito Feeding Habits in Coastal French Guiana: Mammals in the Crosshairs?

Pathogens transmitted by mosquitoes (Diptera, Culicidae) in sylvatic or urban cycles involve wild or domestic animals and humans, driven by various mosquito species with distinct host preferences. Understanding mosquito-host associations is crucial for ecological insights and pathogen surveillance. In this study, we analyzed mosquito blood meals from coastal French Guiana by amplifying and sequencing host DNA from blood-fed females. Using the 12S ribosomal RNA gene and Sanger sequencing, we identified blood meals from 26 mosquito species across six genera, with 59% belonging to the Culex genus. Nanopore sequencing of selected samples showed 12 mosquito species with one to three mixed blood-meal sources. Mammals were the primary hosts (88%), followed by birds (7%), squamates (3%), and amphibians (2%), indicating a strong preference for mammalian hosts. A total of 46 vertebrate host species were identified, demonstrating high host diversity. This research provides insights into mosquito host usage and highlights the complexities of monitoring arboviruses of public health concern.

Impact on Aedes aegypti Mosquitoes Exposed to Honey-Impregnated Flinders Technology Associates (FTA®) Cards.

Programs to control viruses transmitted by mosquitoes requires the implementation of surveillance tools. Over the past decade, Flinders Technology Associates (FTA®) cards, which preserve nucleic acids, have emerged as an innovating surveillance system for collecting arboviruses expectorated during mosquito sugar feeding. In this study, we evaluate the survival rates of two strain of Aedes aegypti (New Orleans (NO) and Cayenne (CAY)) in the laboratory after exposing to either honey-impregnated FTA® cards or untreated filter paper (UFP) card. Experimental exposure of mosquitoes to FTA® cards during sugar feeding significantly negatively impacted their survival, as compared to untreated filter paper. The median survival time was 2 days (95% confidence interval [CI] 1 day, 3 days) for mosquitoes exposed to FTA cards from strain NO and 3 days (95% CI 2 days, 3 days) for mosquitoes exposed to FTA cards from strain CAY. Mosquitoes exposed to UFP did not survive until the end of the experiment (4 days for strain NO and 7 days for strain CAY). Although this finding does not preclude the use of FTA® cards in surveillance, it is crucial to consider and incorporate this factor into study designs.

Engineered skin microbiome reduces mosquito attraction to mice.

The skin microbiome plays a pivotal role in the production of attractive cues detected by mosquitoes. Here, we leveraged recent advances in genetic engineering to significantly reduce the production of L-(+)-lactic acid as a strategy to reduce mosquito attraction to the highly prominent skin commensals Staphylococcus epidermidis and Corynebacterium amycolatum. Engraftment of these engineered bacteria onto the skin of mice reduced mosquito attraction and feeding for up to 11 uninterrupted days, which is considerably longer than the several hours of protection conferred by the leading chemical repellent N,N-diethyl-meta-toluamide. Taken together, our findings demonstrate engineering the skin microbiome to reduce attractive volatiles represents an innovative untapped strategy to reduce vector attraction, preventing bites, and pathogen transmission. These findings set the stage for new classes of long-lasting microbiome-based repellent products.