42,663 research outputs found
Transfected Mosquito Vectors
Get PDFA method is provided for producing an artificial infection in a Culicidae (mosquito) species. The mosquitoes include species within the subfamilies Culicinae and Anophelinae, and the species include Aedes albopictus, Aedes aegypti and Aedes polynesiensis infected with a Wolbachia infection. The infection may be a strain of Wolbachia which does not normally or naturally infect the selected mosquito species. The artificially infected Aedes mosquito can be introduced into a mosquito population to control the reproduction capability of the population by introducing an incompatible Wolbachia infection. The present method can be used as a novel means to limit mosquito-borne pathogens and thus control or prevent mosquito-borne diseases such as dengue, lymphatic filariasis, etc
Mathematical Modelling of Mosquito Dispersal in a Heterogeneous Environment.
Get PDFMosquito dispersal is a key behavioural factor that affects the persistence and resurgence of several vector-borne diseases. Spatial heterogeneity of mosquito resources, such as hosts and breeding sites, affects mosquito dispersal behaviour and consequently affects mosquito population structures, human exposure to vectors, and the ability to control disease transmission. In this paper, we develop and simulate a discrete-space continuous-time mathematical model to investigate the impact of dispersal and heterogeneous distribution of resources on the distribution and dynamics of mosquito populations. We build an ordinary differential equation model of the mosquito life cycle and replicate it across a hexagonal grid (multi-patch system) that represents two-dimensional space. We use the model to estimate mosquito dispersal distances and to evaluate the effect of spatial repellents as a vector control strategy. We find evidence of association between heterogeneity, dispersal, spatial distribution of resources, and mosquito population dynamics. Random distribution of repellents reduces the distance moved by mosquitoes, offering a promising strategy for disease control
Anopheline salivary protein genes and gene families: an evolutionary overview after the whole genome sequence of sixteen Anopheles species
Get PDFBackground: Mosquito saliva is a complex cocktail whose pharmacological properties play an essential role in
blood feeding by counteracting host physiological response to tissue injury. Moreover, vector borne pathogens are
transmitted to vertebrates and exposed to their immune system in the context of mosquito saliva which, in virtue
of its immunomodulatory properties, can modify the local environment at the feeding site and eventually affect
pathogen transmission. In addition, the host antibody response to salivary proteins may be used to assess human
exposure to mosquito vectors. Even though the role of quite a few mosquito salivary proteins has been clarified in
the last decade, we still completely ignore the physiological role of many of them as well as the extent of their
involvement in the complex interactions taking place between the mosquito vectors, the pathogens they transmit
and the vertebrate host. The recent release of the genomes of 16 Anopheles species offered the opportunity to get
insights into function and evolution of salivary protein families in anopheline mosquitoes.
Results: Orthologues of fifty three Anopheles gambiae salivary proteins were retrieved and annotated from 18
additional anopheline species belonging to the three subgenera Cellia, Anopheles, and Nyssorhynchus. Our analysis
included 824 full-length salivary proteins from 24 different families and allowed the identification of 79 novel
salivary genes and re-annotation of 379 wrong predictions. The comparative, structural and phylogenetic analyses
yielded an unprecedented view of the anopheline salivary repertoires and of their evolution over 100 million years
of anopheline radiation shedding light on mechanisms and evolutionary forces that contributed shaping the
anopheline sialomes.
Conclusions: We provide here a comprehensive description, classification and evolutionary overview of the main
anopheline salivary protein families and identify two novel candidate markers of human exposure to malaria vectors
worldwide. This anopheline sialome catalogue, which is easily accessible as hyperlinked spreadsheet, is expected to
be useful to the vector biology community and to improve the capacity to gain a deeper understanding of
mosquito salivary proteins facilitating their possible exploitation for epidemiological and/or pathogen-vector-host
interaction studies
Arboviruses and the challenge to establish systemic and persistent infections in competent mosquito vectors : the interaction with the RNAi mechanism
Get PDFArboviruses are capable to establish long-term persistent infections in mosquitoes that do not affect significantly the physiology of the insect vectors. Arbovirus infections are controlled by the RNAi machinery via the production of viral siRNAs and the formation of RISC complexes targeting viral genomes and mRNAs. Engineered arboviruses that contain cellular gene sequences can therefore be transformed to "viral silencing vectors" for studies of gene function in reverse genetics approaches. More specifically, "ideal" viral silencing vectors must be competent to induce robust RNAi effects while other interactions with the host immune system should be kept at a minimum to reduce non-specific effects. Because of their inconspicuous nature, arboviruses may approach the "ideal" viral silencing vectors in insects and it is therefore worthwhile to study the mechanisms by which the interactions with the RNAi machinery occur. In this review, an analysis is presented of the antiviral RNAi response in mosquito vectors with respect to the major types of arboviruses (alphaviruses, flaviviruses, bunyaviruses, and others). With respect to antiviral defense, the exo-RNAi pathway constitutes the major mechanism while the contribution of both miRNAs and viral piRNAs remains a contentious issue. However, additional mechanisms exist in mosquitoes that are capable to enhance or restrict the efficiency of viral silencing vectors such as the amplification of RNAi effects by DNA forms, the existence of incorporated viral elements in the genome and the induction of a non-specific systemic response by Dicer-2. Of significance is the observation that no major "viral suppressors of RNAi" (VSRs) seem to be encoded by arboviral genomes, indicating that relatively tight control of the activity of the RNA-dependent RNA polymerase (RdRp) may be sufficient to maintain the persistent character of arbovirus infections. Major strategies for improvement of viral silencing vectors therefore are proposed to involve engineering of VSRs and modifying of the properties of the RdRp. Because of safety issues (pathogen status), however, arbovirus-based silencing vectors are not well suited for practical applications, such as RNAi-based mosquito control. In that case, related mosquito-specific viruses that also establish persistent infections and may cause similar RNAi responses may represent a valuable alternative solution
The Effect of Climatic Factors on the Distribution and Abundance of Mosquito Vectors in Ekiti State
Get PDFIn warm and tropical climatic regions of the world, climatic factors have been associated with relative mosquito abundance and transmission of mosquito borne infections. The main objective of this study is to assess the change in seasonal abundance and distribution of mosquito vectors in relation to climate variables (rainfall, temperature and humidity). Mosquito samples were collected from randomly selected houses in all the Local Government Areas of the State using Aspirators, light trap and pyrethrum spray catch methods from July 2006 to June 2008. Species of Anopheles, Aedes and Culex mosquitoes were collected. Anopheles gambiae s.s had the highest number (43.5%) out the three malaria vectors found. For Aedes and Culex species collected, Aedes aegypti (37.6%) and Culex fatigans (37.1%) have the highest prevalence out of their sibling species. Temperature and Rainfall were highly correlated with the abundance of mosquito vectors. It was observed that relative humidity of at least 50- 55% prolong mosquito survival. The rainy season (March to October) recorded the highest number of mosquito vectors collection with the peak in the months of July and August while the lowest collection was in the month of February when there was little or no rains. The environmental and ecological factors including Human activities enhanced the breeding and abundance of these mosquito vectors. Keywords: Culex fatigans; Aedes aegypti; Mosquito; rainfall; temperature; abundanc
The olfactory basis of orchid pollination by mosquitoes.
Get PDFMosquitoes are important vectors of disease and require sources of carbohydrates for reproduction and survival. Unlike host-related behaviors of mosquitoes, comparatively less is understood about the mechanisms involved in nectar-feeding decisions, or how this sensory information is processed in the mosquito brain. Here we show that Aedes spp. mosquitoes, including Aedes aegypti, are effective pollinators of the Platanthera obtusata orchid, and demonstrate this mutualism is mediated by the orchid's scent and the balance of excitation and inhibition in the mosquito's antennal lobe (AL). The P. obtusata orchid emits an attractive, nonanal-rich scent, whereas related Platanthera species-not visited by mosquitoes-emit scents dominated by lilac aldehyde. Calcium imaging experiments in the mosquito AL revealed that nonanal and lilac aldehyde each respectively activate the LC2 and AM2 glomerulus, and remarkably, the AM2 glomerulus is also sensitive to N,N-diethyl-meta-toluamide (DEET), a mosquito repellent. Lateral inhibition between these 2 glomeruli reflects the level of attraction to the orchid scents. Whereas the enriched nonanal scent of P. obtusata activates the LC2 and suppresses AM2, the high level of lilac aldehyde in the other orchid scents inverts this pattern of glomerular activity, and behavioral attraction is lost. These results demonstrate the ecological importance of mosquitoes beyond operating as disease vectors and open the door toward understanding the neural basis of mosquito nectar-seeking behaviors
Anthropogenic impacts on mosquito populations in North America over the past century.
Get PDFThe recent emergence and spread of vector-borne viruses including Zika, chikungunya and dengue has raised concerns that climate change may cause mosquito vectors of these diseases to expand into more temperate regions. However, the long-term impact of other anthropogenic factors on mosquito abundance and distributions is less studied. Here, we show that anthropogenic chemical use (DDT; dichlorodiphenyltrichloroethane) and increasing urbanization were the strongest drivers of changes in mosquito populations over the last eight decades in areas on both coasts of North America. Mosquito populations have increased as much as tenfold, and mosquito communities have become two- to fourfold richer over the last five decades. These increases are correlated with the decay in residual environmental DDT concentrations and growing human populations, but not with temperature. These results illustrate the far-reaching impacts of multiple anthropogenic disturbances on animal communities and suggest that interactions between land use and chemical use may have unforeseen consequences on ecosystems
A study of the distribution and abundance of the adult malaria vector in western Kenya highlands
Get PDF<p>Abstract</p> <p>Background</p> <p>A sharp rise in the malaria mortality rate has been observed recently in western Kenya. Malaria is transmitted by mosquito vectors. Malaria control strategies can be more successful if the distribution and abundance of mosquito vectors is predicted. However, how mosquito vectors are distributed in space remain poor understood, and this question is rarely studied using spatial methods. This study aims to provide a better understanding of the distribution and abundance of mosquito vectors. To achieve this objective, spatial and non-spatial methods were employed. The data on the distribution of adult mosquitoes, and mosquito breeding habitats in a study area in western Kenya, and environmental variables were analyzed.</p> <p>Results</p> <p>The models developed using spatial methods outperformed the models developed using non-spatial methods. Houses close to locations where mosquito breeding habitats were repeatedly observed had more abundant adult female mosquitoes. Distance to high-order streams was identified as an effective predictor for the distribution of adult mosquitoes.</p> <p>Conclusion</p> <p>The spatial method is more effective in modeling the distribution of adult mosquitoes than the non-spatial method. The results of this study can be used to facilitate decision-making related to mosquito surveillance and malaria prevention.</p
Ecology: a prerequisite for malaria elimination and eradication
Get PDF* Existing front-line vector control measures, such as insecticide-treated nets and residual sprays, cannot break the transmission cycle of Plasmodium falciparum in the most intensely endemic parts of Africa and the Pacific
* The goal of malaria eradication will require urgent strategic investment into understanding the ecology and evolution of the mosquito vectors that transmit malaria
* Priority areas will include understanding aspects of the mosquito life cycle beyond the blood feeding processes which directly mediate malaria transmission
* Global commitment to malaria eradication necessitates a corresponding long-term commitment to vector ecolog
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