The impact of uniform and mixed species blood meals on the fitness of the mosquito vector Anopheles gambiae s.s: does a specialist pay for diversifying its host species diet?

Abstract Background Knowledge on mosquito attraction to various host-mimicking odors provides a potential opportunity for designing effective tools for surveillance and control of potential disease vectors. This study was carried out to explore the potential of combining plant and human mimicking odours to attract Anopheles gambiae s. s . in the laboratory and semi field settings in Tanzania. Methodology Blood fed and unfed female Anopheles gambiae s.s. mosquitoes were offered choices between human skin, plant-based odours or combination thereof in laboratory and semi-field setting. The captured mosquitoes from each source were scored for comparison. Results In laboratory and semi-field trials, the tested attractants combination of plant and human-mimicking odours found to be slightly attractive (approximately 10% higher) than either individual attractant to blood fed female mosquitoes under lab and semi-field settings. The unfed female mosquitoes were more attracted to Vectrax (plant-based materials) by more than 10% in comparison to human skin-based attractant both in lab and semi-field settings. In semi-field settings particularly, more unfed female mosquitoes were attracted to Vectrax than to the combination (p < 0.01). Conclusions The findings that the combination blend (human host and plant based) semiochemical increases mosquito attraction hold the potential to increase efficiency of mosquitoes trapping devices in both indoor and outdoor settings. This may provide valuable tools for mosquito vector management programs. Moreover, these results also suggest the potential of the combination odours to be used in the attract and kill strategies.

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Transcriptome Profiles of Anopheles gambiae Harboring Natural Low-Level Plasmodium Infection Reveal Adaptive Advantages for the Mosquito

10.1101/2021.08.02.454766 ◽

2021 ◽

Author(s):

Ann L Carr ◽

David Rinker ◽

Yuemei Dong ◽

George Dimopoulos ◽

LJ Zwiebel

Keyword(s):

Anopheles Gambiae ◽

Transcript Abundance ◽

Plasmodium Infection ◽

Anopheles Gambiae S.S ◽

Molecular Physiology ◽

Low Level ◽

Olfactory Acuity ◽

Evolutionary Success ◽

Open Question ◽

The Impact

Anopheline mosquitoes are the sole vectors for the Plasmodium pathogens responsible for malaria, which is among the oldest and most devastating of human diseases. The continuing global impact of malaria reflects the evolutionary success of a complex vector-pathogen relationship that accordingly has been the long-term focus of both debate and study. An open question in the biology of malaria transmission is the impact of naturally occurring low-level Plasmodium infections of the vector on mosquito health and longevity as well as critical behaviors such as host-preference/seeking. To begin to answer this, we have completed a comparative RNAseq-based transcriptome profile study examining the effect of biologically salient, salivary gland transmission-stage Plasmodium infection on the molecular physiology of Anopheles gambiae s.s. head, sensory appendage, and salivary glands. When compared with their uninfected counterparts, Plasmodium infected mosquitoes exhibit increased transcript abundance of genes associated with olfactory acuity as well as a range of synergistic processes that align with increased fitness based on both anti-aging and reproductive advantages. Taken together, these data argue against the long-held paradigm that malaria infection is pathogenic for anophelines and, instead, suggests there are biological and evolutionary advantages for the mosquito that drive the preservation of its high vectorial capacity.

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Infection Intensity-Dependent Responses of Anopheles gambiae to the African Malaria Parasite Plasmodium falciparum

Infection and Immunity ◽

10.1128/iai.05647-11 ◽

2011 ◽

Vol 79 (11) ◽

pp. 4708-4715 ◽

Cited By ~ 35

Author(s):

Antonio M. Mendes ◽

Parfait H. Awono-Ambene ◽

Sandrine E. Nsango ◽

Anna Cohuet ◽

Didier Fontenille ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Anopheles Gambiae ◽

Transcriptional Response ◽

Infection Intensity ◽

Mosquito Vector ◽

Content Type ◽

Parasite Plasmodium Falciparum ◽

Control And Prevention ◽

Functional Classes ◽

The Impact

ABSTRACTMalaria remains a devastating disease despite efforts at control and prevention. Extensive studies using mostly rodent infection models reveal that successfulPlasmodiumparasite transmission by the African mosquito vectorAnopheles gambiaedepends on finely tuned vector-parasite interactions. Here we investigate the transcriptional response ofA. gambiaeto geographically relatedPlasmodium falciparumpopulations at various infection intensities and different infection stages. These responses are compared with those of mosquitoes infected with the rodent parasitePlasmodium berghei. We demonstrate that mosquito responses are largely dependent on the intensity of infection. A major transcriptional suppression of genes involved in the regulation of midgut homeostasis is detected in low-intensityP. falciparuminfections, the most common type of infection in Africa. Importantly, genes transcriptionally induced during these infections tend to be phylogenetically unique toA. gambiae. These data suggest that coadaptation between vectors and parasites may act to minimize the impact of infection on mosquito fitness by selectively suppressing specific functional classes of genes. RNA interference (RNAi)-mediated gene silencing provides initial evidence for important roles of the mosquito G protein-coupled receptors (GPCRs) in controlling infection intensity-dependent antiparasitic responses.

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A pyrethroïd-treated bed net increases host attractiveness for Anopheles gambiae s.s. carrying the kdr allele in a dual-choice olfactometer

10.1101/077552 ◽

2016 ◽

Cited By ~ 1

Author(s):

Angélique Porciani ◽

Malal Diop ◽

Nicolas Moiroux ◽

Tatiana Kadoke-Lambi ◽

Anna Cohuet ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Gambiae ◽

Sub Saharan Africa ◽

Malaria Vectors ◽

Malaria Vector Control ◽

Anopheles Gambiae S.S ◽

Host Seeking ◽

Seeking Behavior ◽

Sub Saharan ◽

The Impact

AbstractThe use of long lasting insecticide nets (LLINs) treated with pyrethroïd is known for its major contribution in malaria control. However, LLINs are suspected to induce behavioral changes in malaria vectors, which may in turn drastically affect their efficacy against Plasmodium sp. transmission. In sub Saharan Africa, where malaria imposes the heaviest burden, the main malaria vectors are widely resistant to pyrethroïds, the insecticide family used on LLINs, which also threatens LLIN efficiency. There is therefore a crucial need for deciphering how insecticide-impregnated materials might affect the host-seeking behavior of malaria vectors in regards to insecticide resistance. In this study, we explored the impact of permethrin-impregnated net on the host attractiveness for Anopheles gambiae mosquitoes, either susceptible to insecticides, or carrying the insecticide resistance conferring allele kdr. Groups of female mosquitoes were released in a dual-choice olfactometer and their movements towards an attractive odor source (a rabbit) protected by insecticide-treated (ITN) or untreated nets (UTN) were monitored. Kdr homozygous mosquitoes, resistant to insecticides, were more attracted by a host behind an ITN than an UTN, while the presence of insecticide on the net did not affect the choice of susceptible mosquitoes. These results suggest that permethrin-impregnated net is detectable by malaria vectors and that the kdr mutation impacts their response to a LLIN protected host. We discuss the implication of these results for malaria vector control.

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The environmental and ecological determinants of elevated Ross River Virus exposure in koalas residing in urban coastal landscapes

Scientific Reports ◽

10.1038/s41598-021-83919-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Brian J. Johnson ◽

Amy Robbins ◽

Narayan Gyawali ◽

Oselyne Ong ◽

Joanne Loader ◽

...

Keyword(s):

Animal Movement ◽

Ross River Virus ◽

Mosquito Vector ◽

Large Numbers ◽

Culex Annulirostris ◽

Coastal Landscapes ◽

In The Wild ◽

Virus Exposure ◽

Elevated Exposure ◽

The Impact

AbstractKoala populations in many areas of Australia have declined sharply in response to habitat loss, disease and the effects of climate change. Koalas may face further morbidity from endemic mosquito-borne viruses, but the impact of such viruses is currently unknown. Few seroprevalence studies in the wild exist and little is known of the determinants of exposure. Here, we exploited a large, spatially and temporally explicit koala survey to define the intensity of Ross River Virus (RRV) exposure in koalas residing in urban coastal environments in southeast Queensland, Australia. We demonstrate that RRV exposure in koalas is much higher (> 80%) than reported in other sero-surveys and that exposure is uniform across the urban coastal landscape. Uniformity in exposure is related to the presence of the major RRV mosquito vector, Culex annulirostris, and similarities in animal movement, tree use, and age-dependent increases in exposure risk. Elevated exposure ultimately appears to result from the confinement of remaining coastal koala habitat to the edges of permanent wetlands unsuitable for urban development and which produce large numbers of competent mosquito vectors. The results further illustrate that koalas and other RRV-susceptible vertebrates may serve as useful sentinels of human urban exposure in endemic areas.

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Understanding mosquito host-choice behaviour: a new and low-cost method of identifying the sex of human hosts from mosquito blood meals

Parasites & Vectors ◽

10.1186/s13071-021-04577-w ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Fiona Teltscher ◽

Sophie Bouvaine ◽

Gabriella Gibson ◽

Paul Dyer ◽

Jennifer Guest ◽

...

Keyword(s):

Blood Meal ◽

Host Species ◽

Disease Transmission ◽

Low Cost ◽

Host Choice ◽

Epidemiological Models ◽

Choice Behaviour ◽

Vector Borne ◽

Transmission Models ◽

Blood Meals

Abstract Background Mosquito-borne diseases are a global health problem, causing hundreds of thousands of deaths per year. Pathogens are transmitted by mosquitoes feeding on the blood of an infected host and then feeding on a new host. Monitoring mosquito host-choice behaviour can help in many aspects of vector-borne disease control. Currently, it is possible to determine the host species and an individual human host from the blood meal of a mosquito by using genotyping to match the blood profile of local inhabitants. Epidemiological models generally assume that mosquito biting behaviour is random; however, numerous studies have shown that certain characteristics, e.g. genetic makeup and skin microbiota, make some individuals more attractive to mosquitoes than others. Analysing blood meals and illuminating host-choice behaviour will help re-evaluate and optimise disease transmission models. Methods We describe a new blood meal assay that identifies the sex of the person that a mosquito has bitten. The amelogenin locus (AMEL), a sex marker located on both X and Y chromosomes, was amplified by polymerase chain reaction in DNA extracted from blood-fed Aedes aegypti and Anopheles coluzzii. Results AMEL could be successfully amplified up to 24 h after a blood meal in 100% of An. coluzzii and 96.6% of Ae. aegypti, revealing the sex of humans that were fed on by individual mosquitoes. Conclusions The method described here, developed using mosquitoes fed on volunteers, can be applied to field-caught mosquitoes to determine the host species and the biological sex of human hosts on which they have blood fed. Two important vector species were tested successfully in our laboratory experiments, demonstrating the potential of this technique to improve epidemiological models of vector-borne diseases. This viable and low-cost approach has the capacity to improve our understanding of vector-borne disease transmission, specifically gender differences in exposure and attractiveness to mosquitoes. The data gathered from field studies using our method can be used to shape new transmission models and aid in the implementation of more effective and targeted vector control strategies by enabling a better understanding of the drivers of vector-host interactions.

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The regulatory genome of the malaria vector Anopheles gambiae: integrating chromatin accessibility and gene expression

NAR Genomics and Bioinformatics ◽

10.1093/nargab/lqaa113 ◽

2021 ◽

Vol 3 (1) ◽

Author(s):

José L Ruiz ◽

Lisa C Ranford-Cartwright ◽

Elena Gómez-Díaz

Keyword(s):

Gene Expression ◽

Transcriptional Regulation ◽

Anopheles Gambiae ◽

Mosquito Control ◽

Regulatory Elements ◽

Chromatin Accessibility ◽

Malaria Vectors ◽

Specific Gene ◽

Mosquito Vector ◽

Human Malaria

Abstract Anopheles gambiae mosquitoes are primary human malaria vectors, but we know very little about their mechanisms of transcriptional regulation. We profiled chromatin accessibility by the assay for transposase-accessible chromatin by sequencing (ATAC-seq) in laboratory-reared A. gambiae mosquitoes experimentally infected with the human malaria parasite Plasmodium falciparum. By integrating ATAC-seq, RNA-seq and ChIP-seq data, we showed a positive correlation between accessibility at promoters and introns, gene expression and active histone marks. By comparing expression and chromatin structure patterns in different tissues, we were able to infer cis-regulatory elements controlling tissue-specific gene expression and to predict the in vivo binding sites of relevant transcription factors. The ATAC-seq assay also allowed the precise mapping of active regulatory regions, including novel transcription start sites and enhancers that were annotated to mosquito immune-related genes. Not only is this study important for advancing our understanding of mechanisms of transcriptional regulation in the mosquito vector of human malaria, but the information we produced also has great potential for developing new mosquito-control and anti-malaria strategies.

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