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Background Long-lasting insecticidal nets (LLINs) are ineffective malaria transmission prevention tools if they are unused. Discomfort due to heat is the most commonly reported reason for not using nets, but this problem is largely unaddressed. With increasing rural electrification and the dropping price of solar power, fans could improve comfort inside nets and be affordable to populations in malaria endemic areas. Here, results are presented from a pilot randomized controlled cross-over study testing the effect of fans on LLIN use. Methods Eighty-three households from two rural communities in Greater Accra, Ghana, randomized into three groups, participated in a 10-month cross-over trial. After a screening survey to identify eligible households, all households received new LLINs. B[reversed sigma]k[reversed sigma][reversed sigma] net fan systems (one fan per member) were given to households in Group 1 and water filters were given to households in Group 2. At mid-point, Group 1 and 2 crossed over interventions. Households in Group 1 and 2 participated in fortnightly surveys on households' practices related to nets, fans and water filters, while households in Group 3 were surveyed only at screening, mid-point and study end. Entomological and weather data were collected throughout the study. Analysis took both 'per protocol' (PP) and 'intention to treat' (ITT) approaches. The mid- and end-point survey data from Group 1 and 2 were analysed using Firth logistic regressions. Fortnightly survey data from all groups were analysed using logistic regressions with random effects. Results Provision of fans to households appeared to increase net use in this study. Although the increase in net use explained by fans was not significant in the primary analyses (ITT odds ratio 3.24, p > 0.01; PP odds ratio = 1.17, p > 0.01), it was significant in secondary PP analysis (odds ratio = 1.95, p < 0.01). Net use was high at screening and even higher after provision of new LLINs and with follow up. Fan use was 90-100% depending on the fortnightly visit. Conclusions This pilot study could not provide definitive evidence that fans increase net use. A larger study with additional statistical power is needed to assess this association across communities with diverse environmental and socio-demographic characteristics.

Twenty-seven villages were selected in southwest Burkina Faso to implement new vector control strategies in addition to long lasting insecticidal nets (LLINs) through a Randomized Controlled Trial (RCT). We conducted entomological surveys in the villages during the dry cold season (January 2017), dry hot season (March 2017) and rainy season (June 2017) to describe malaria vectors bionomics, insecticide resistance and transmission prior to this trial. We carried out hourly catches (from 17:00 to 09:00) inside and outside 4 houses in each village using the Human Landing Catch technique. Mosquitoes were identified using morphological taxonomic keys. Specimens belonging to the Anopheles gambiae complex and Anopheles funestus group were identified using molecular techniques as well as detection of Plasmodium falciparum infection and insecticide resistance target-site mutations. Eight Anopheles species were detected in the area. Anopheles funestus s.s was the main vector during the dry cold season. It was replaced by Anopheles coluzzii during the dry hot season whereas An. coluzzii and An. gambiae s.s. were the dominant species during the rainy season. Species composition of the Anopheles population varied significantly among seasons. All insecticide resistance mechanisms (kdr-w, kdr-e and ace-1 target site mutations) investigated were found in each members of the An. gambiae complex but at different frequencies. We observed early and late biting phenotypes in the main malaria vector species. Entomological inoculation rates were 2.61, 2.67 and 11.25 infected bites per human per month during dry cold season, dry hot season and rainy season, respectively. The entomological indicators of malaria transmission were high despite the universal coverage with LLINs. We detected early and late biting phenotypes in the main malaria vector species as well as physiological insecticide resistance mechanisms. These data will be used to evaluate the impact of complementary tools to LLINs in an upcoming RCT.

Mosquito surveillance in remote areas with limited access to canisters of CO sub( 2) or dry ice will benefit from an effective alternative CO sub( 2) source, such as the natural production of CO sub( 2) from yeast fermentation. In this study, we investigate differences in mosquito capture rates from the Centers for Disease Control and Prevention (CDC) light traps baited with dry ice compared with traps baited with yeast fermentation of several carbohydrate sources over 23 trap-nights. Results demonstrated the ability of yeast-generated CO sub( 2) to effectively attract mosquitoes to a CDC trap, regardless of carbohydrate source. Total collections of mosquitoes using dry ice were significantly higher than collections from yeast-generated CO sub( 2) sources. However, mosquito community structure, i.e., the species and relative capture rate of each species, was represented comparably across collections regardless of CO sub( 2) source. Volatiles produced by yeast fermentation were analyzed by carbohydrate source, revealing a suite of compounds, possibly synergistic, enhancing effects with CO sub( 2) on mosquito collection capability compared with the amount of CO sub( 2) used to attract mosquitoes.

The fight against diseases spread by mosquitoes and other insects has enormous environmental, economic and social consequences. Chemical insecticides remain the first line of defence but the control of diseases, especially malaria and dengue fever, is being increasingly undermined by insecticide resistance. Mosquitoes have a large repertoire of P450s (over 100 genes). By pinpointing the key enzymes associated with insecticide resistance we can begin to develop new tools to aid the implementation of control interventions and reduce their environmental impact on Earth. Recent technological advances are helping us to build a functional profile of the P450 determinants of insecticide metabolic resistance in mosquitoes. Alongside, the cross-responses of mosquito P450s to insecticides and pollutants are also being investigated. Such research will provide the means to produce diagnostic tools for early detection of P450s linked to resistance. It will also enable the design of new insecticides with optimized efficacy in different environments.

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.

This study reports the first records of the genus ShannonianaLane & Cerqueira, 1942 and Trichoprosopon aff. castroiLane & Cerqueira, 1942 in Peru, both belonging to the Sabethini tribe of mosquitoes. Fieldwork was conducted in the Cerro Adobe conservation center in the Amazonas region, where ovitraps were used to collect mosquito larvae, which were then reared in the laboratory for identification. Morphological and molecular analyses confirmed the presence of these species, with Shannoniana showing differences from previously described species, and Trichoprosopon aff. castroi being recognized as a new record of this species for Peru. Phylogenetic analysis of COI sequences revealed 3 distinct genetic lineages, supporting the monophyly of Sabethini but indicating inconsistencies in the internal relationships within the genus Trichoprosopon. This work expands the known diversity of Sabethini mosquitoes in Peru and underscores the value of molecular tools in resolving taxonomic challenges in mosquito studies.

Mosquitoes are major infectious disease-carrying vectors. Assessment of current and future risks associated with the mosquito population requires knowledge of the full repertoire of pathogens they carry, including novel viruses, as well as their blood meal sources. Unbiased metatranscriptomic sequencing of individual mosquitoes offers a straightforward, rapid, and quantitative means to acquire this information. Here, we profile 148 diverse wild-caught mosquitoes collected in California and detect sequences from eukaryotes, prokaryotes, 24 known and 46 novel viral species. Importantly, sequencing individuals greatly enhanced the value of the biological information obtained. It allowed us to (a) speciate host mosquito, (b) compute the prevalence of each microbe and recognize a high frequency of viral co-infections, (c) associate animal pathogens with specific blood meal sources, and (d) apply simple co-occurrence methods to recover previously undetected components of highly prevalent segmented viruses. In the context of emerging diseases, where knowledge about vectors, pathogens, and reservoirs is lacking, the approaches described here can provide actionable information for public health surveillance and intervention decisions.

Background Malaria control through use of long-lasting insecticidal nets (LN) is threatened by the selection of anopheline mosquitoes strongly resistant to pyrethroid insecticides. To sustain future effectiveness it is essential to identify and evaluate novel insecticides suitable for nets. Mixtures of two insecticides with contrasting mode of action have the potential to kill resistant vectors and restore transmission control provided the formulation can withstand regular washing over the net's life span. Method The efficacy of a novel mixture LN, Interceptor registered G2, that combines the pyrrole chlorfenapyr and pyrethroid alpha-cypermethrin was evaluated under controlled household conditions (experimental hut trial) and by laboratory bioassay against pyrethroid resistant An. gambiae in Benin before and after standardized washing. Comparison arms included standard alpha-cypermethrin LN, nets hand-treated with chlorfenapyr-only and untreated nets. Results The chlorfenapyr-alphacypermethrin LN demonstrated improved efficacy and wash resistance compared to a standard alpha-cypermethrin LN against pyrethroid resistant mosquitoes (resistance ratio 207). In experimental hut trial alpha-cypermethrin LN killed only 20% (95% CI 15-26%) of host-seeking An. gambiae whilst mixture LN killed 71% (95% CI 65-77%). Mixture LN washed 20 times killed 65% (95% CI 58-71%), and thus intensive washing reduced efficacy by only 6% (95% CI 1.3-11%). The chlorfenapyr net killed 76% (95% CI 70-81%). Personal protection and blood feeding inhibition did not differ between mixture and pyrethroid LN; however, the mixture LN was 2.5 (95% CI: 2.1-3.1) times more protective than untreated nets. Standard WHO cone bioassays conducted during day time hours failed to anticipate field efficacy but overnight tunnel tests successfully predicted mixture LN and chlorfenapyr net efficacy in field trials. Conclusion Interceptor registered G2 LN demonstrates the potential to control transmission and provide community protection over the normal lifespan of long lasting nets where standard pyrethroid LN show signs of failing due to resistance.

Malaria transmission is highly heterogeneous, generating malaria hotspots that can fuel malaria transmission across a wider area. Targeting hotspots may represent an efficacious strategy for reducing malaria transmission. We determined the impact of interventions targeted to serologically defined malaria hotspots on malaria transmission both inside hotspots and in surrounding communities. Twenty-seven serologically defined malaria hotspots were detected in a survey conducted from 24 June to 31 July 2011 that included 17,503 individuals from 3,213 compounds in a 100-km2 area in Rachuonyo South District, Kenya. In a cluster-randomized trial from 22 March to 15 April 2012, we randomly allocated five clusters to hotspot-targeted interventions with larviciding, distribution of long-lasting insecticide-treated nets, indoor residual spraying, and focal mass drug administration (2,082 individuals in 432 compounds); five control clusters received malaria control following Kenyan national policy (2,468 individuals in 512 compounds). Our primary outcome measure was parasite prevalence in evaluation zones up to 500 m outside hotspots, determined by nested PCR (nPCR) at baseline and 8 wk (16 June-6 July 2012) and 16 wk (21 August-10 September 2012) post-intervention by technicians blinded to the intervention arm. Secondary outcome measures were parasite prevalence inside hotpots, parasite prevalence in the evaluation zone as a function of distance from the hotspot boundary, Anopheles mosquito density, mosquito breeding site productivity, malaria incidence by passive case detection, and the safety and acceptability of the interventions. Intervention coverage exceeded 87% for all interventions. Hotspot-targeted interventions did not result in a change in nPCR parasite prevalence outside hotspot boundaries (p ≥ 0.187). We observed an average reduction in nPCR parasite prevalence of 10.2% (95% CI -1.3 to 21.7%) inside hotspots 8 wk post-intervention that was statistically significant after adjustment for covariates (p = 0.024), but not 16 wk post-intervention (p = 0.265). We observed no statistically significant trend in the effect of the intervention on nPCR parasite prevalence in the evaluation zone in relation to distance from the hotspot boundary 8 wk (p = 0.27) or 16 wk post-intervention (p = 0.75). Thirty-six patients with clinical malaria confirmed by rapid diagnostic test could be located to intervention or control clusters, with no apparent difference between the study arms. In intervention clusters we caught an average of 1.14 female anophelines inside hotspots and 0.47 in evaluation zones; in control clusters we caught an average of 0.90 female anophelines inside hotspots and 0.50 in evaluation zones, with no apparent difference between study arms. Our trial was not powered to detect subtle effects of hotspot-targeted interventions nor designed to detect effects of interventions over multiple transmission seasons. Despite high coverage, the impact of interventions targeting malaria vectors and human infections on nPCR parasite prevalence was modest, transient, and restricted to the targeted hotspot areas. Our findings suggest that transmission may not primarily occur from hotspots to the surrounding areas and that areas with highly heterogeneous but widespread malaria transmission may currently benefit most from an untargeted community-wide approach. Hotspot-targeted approaches may have more validity in settings where human settlement is more nuclear. ClinicalTrials.gov NCT01575613.