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1.
Biomed Res Int ; 2021: 6619175, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33884266

RESUMO

Background: To date, dengue is considered an important public health problem in Sri Lanka. Irrational use of insecticides without evidence-based applications has primed the development of resistance in mosquito vectors. Method: The present study investigated the resistance status of Aedes aegypti and Aedes albopictus to commonly used insecticides in three selected Medical Officer of Health (MOH) areas (i.e., Attanagalla, Dompe, and Negombo) in Gampaha District, Western Province of Sri Lanka. Entomological surveys were performed using ovitraps and larval collections. Larval bioassays were carried out to determine the LC50, LC90, and LC95 and susceptibility status for organophosphate temephos, whereas adult bioassays were performed to test the 0.03% deltamethrin and 0.8% malathion susceptibility. Results: The study revealed that the temephos concentrations required to control Ae. aegypti (13.7-17.7 times) and Ae. albopictus (4.6-7.6 times) are higher than the diagnostic concentration (0.012 mg/L) proposed by the World Health Organization. The highest resistance levels were observed for both Ae. aegypti (14 ± 1.87) and Ae. albopictus (36 ± 1.87) collected from the Negombo MOH area. Therefore, the WHO recommended diagnostic concentration is no longer effective in controlling Ae. aegypti and Ae. albopictus larvae in these areas. Both the dengue vectors have evolved a high level of insecticide resistance to malathion and deltamethrin in the Gampaha District except Ae. albopictus mosquitoes in rural areas. Further, vectors in rural areas are indicated susceptible (>98%) to pyrethroids and emergence of resistance (<97%) for organophosphate insecticides. Conclusion: The results of this study warrant the vector management authorities on the proper application of insecticides and rational use in vector control. The susceptibility status of vector mosquitoes should be continuously monitored especially in dengue-endemic areas parallel to the routine surveillance programme. Further molecular studies are strongly recommended to determine the Knockdown Resistance (kdr) mutations among Aedes populations.


Assuntos
Aedes/fisiologia , Dengue/prevenção & controle , Dengue/parasitologia , Vetores de Doenças , Resistência a Inseticidas , Mosquitos Vetores/fisiologia , Animais , Feminino , Geografia , Inseticidas/toxicidade , Larva/efeitos dos fármacos , Sri Lanka , Temefós/toxicidade
2.
J Vis Exp ; (169)2021 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-33779612

RESUMO

The control of such human diseases as dengue, Zika, and chikungunya relies on the control of their vector, the Aedes aegypti mosquito, because there is no prevention. Control of mosquito vectors can rely on chemicals applied to the immature and adult stages, which can contribute to the mortality of non-targets and more importantly, lead to insecticide resistance in the vector. The sterile insect technique (SIT) is a method of controlling populations of pests through the release of sterilized adult males that mate with wild females to produce non-viable offspring. This paper describes the process of producing sterile males for use in an operational SIT program for the control of Aedes aegypti mosquitoes. Outlined here are the steps used in the program including rearing and maintaining a colony, separating male and female pupae, irradiating and marking adult males, and shipping Aedes aegypti males to the release site. Also discussed are procedural caveats, program limitations, and future objectives.


Assuntos
Aedes/fisiologia , Fertilidade/efeitos da radiação , Resistência a Inseticidas , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , Pupa/fisiologia , Esterilização Reprodutiva/métodos , Aedes/efeitos da radiação , Animais , Feminino , Humanos , Masculino , Mosquitos Vetores/efeitos da radiação , Pupa/efeitos da radiação
3.
PLoS Negl Trop Dis ; 15(3): e0009259, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33705409

RESUMO

Dengue, Zika and chikungunya are diseases of global health significance caused by arboviruses and transmitted by the mosquito Aedes aegypti, which is of worldwide circulation. The arrival of the Zika and chikungunya viruses to South America increased the complexity of transmission and morbidity caused by these viruses co-circulating in the same vector mosquito species. Here we present an integrated analysis of the reported arbovirus cases between 2007 and 2017 and local climate and socio-economic profiles of three distinct Colombian municipalities (Bello, Cúcuta and Moniquirá). These locations were confirmed as three different ecosystems given their contrasted geographic, climatic and socio-economic profiles. Correlational analyses were conducted with both generalised linear models and generalised additive models for the geographical data. Average temperature, minimum temperature and wind speed were strongly correlated with disease incidence. The transmission of Zika during the 2016 epidemic appeared to decrease circulation of dengue in Cúcuta, an area of sustained high incidence of dengue. Socio-economic factors such as barriers to health and childhood services, inadequate sanitation and poor water supply suggested an unfavourable impact on the transmission of dengue, Zika and chikungunya in all three ecosystems. Socio-demographic influencers were also discussed including the influx of people to Cúcuta, fleeing political and economic instability from neighbouring Venezuela. Aedes aegypti is expanding its range and increasing the global threat of these diseases. It is therefore vital that we learn from the epidemiology of these arboviruses and translate it into an actionable local knowledge base. This is even more acute given the recent historical high of dengue cases in the Americas in 2019, preceding the COVID-19 pandemic, which is itself hampering mosquito control efforts.


Assuntos
Febre de Chikungunya/epidemiologia , Dengue/epidemiologia , Infecção por Zika virus/epidemiologia , Aedes/fisiologia , Aedes/virologia , Animais , Febre de Chikungunya/economia , Febre de Chikungunya/virologia , Vírus Chikungunya/fisiologia , Clima , Colômbia/epidemiologia , Dengue/economia , Dengue/virologia , Vírus da Dengue/fisiologia , Fatores Econômicos , Ecossistema , Humanos , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , América do Sul , Temperatura , Zika virus/fisiologia , Infecção por Zika virus/economia , Infecção por Zika virus/virologia
4.
Acta Trop ; 218: 105885, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33713628

RESUMO

Aedes aegypti and Aedes albopictus are mosquito vectors of numerous arboviruses of sanitary importance. Presently in Argentina, neither Ae. aegypti nor Ae. albopictus, have displaced the other species in the places where they coexist, since the introduction of the latter in 1998. In this study, we evaluated whether these species coexist at different scales (ovitrap, microhabitat and habitat) in the city of Eldorado, Misiones province, northeast Argentina. We also analyzed the seasonal variation and climate variables related to the delay in egg hatching of both species. Mosquitoes were collected weekly, from June 2017 to May 2018, using ovitraps placed in urban areas. We conclude that Ae. aegypti and Ae. albopictus coexist in the study area, at the ovitrap, microhabitat and habitat scales. Furthermore, no pronounced pattern of delayed hatching has been observed for either species; however, eggs of Ae. albopictus laid during colder weeks and less rainfall needed a greater number of immersions to hatch, while for Ae. aegypti those laid during weeks with low rainfall and high temperatures showed the longest delay in hatching response.


Assuntos
Aedes/fisiologia , Aedes/virologia , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Ovulação , Clima Tropical , Animais , Arbovírus/fisiologia , Argentina , Cidades , Ecossistema , Estações do Ano
5.
Nat Commun ; 12(1): 909, 2021 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-33568678

RESUMO

Malaria control may be enhanced by targeting reservoirs of Plasmodium falciparum transmission. One putative reservoir is asymptomatic malaria infections and the scale of their contribution to transmission in natural settings is not known. We assess the contribution of asymptomatic malaria to onward transmission using a 14-month longitudinal cohort of 239 participants in a high transmission site in Western Kenya. We identify P. falciparum in asymptomatically- and symptomatically-infected participants and naturally-fed mosquitoes from their households, genotype all parasites using deep sequencing of the parasite genes pfama1 and pfcsp, and use haplotypes to infer participant-to-mosquito transmission through a probabilistic model. In 1,242 infections (1,039 in people and 203 in mosquitoes), we observe 229 (pfcsp) and 348 (pfama1) unique parasite haplotypes. Using these to link human and mosquito infections, compared with symptomatic infections, asymptomatic infections more than double the odds of transmission to a mosquito among people with both infection types (Odds Ratio: 2.56; 95% Confidence Interval (CI): 1.36-4.81) and among all participants (OR 2.66; 95% CI: 2.05-3.47). Overall, 94.6% (95% CI: 93.1-95.8%) of mosquito infections likely resulted from asymptomatic infections. In high transmission areas, asymptomatic infections are the major contributor to mosquito infections and may be targeted as a component of transmission reduction.


Assuntos
Anopheles/parasitologia , Malária Falciparum/parasitologia , Malária Falciparum/transmissão , Mosquitos Vetores/parasitologia , Plasmodium falciparum/genética , Adulto , Animais , Anopheles/fisiologia , Infecções Assintomáticas/epidemiologia , Estudos de Coortes , Feminino , Genótipo , Humanos , Quênia/epidemiologia , Estudos Longitudinais , Malária Falciparum/epidemiologia , Masculino , Mosquitos Vetores/fisiologia , Plasmodium falciparum/classificação , Plasmodium falciparum/isolamento & purificação
6.
BMC Infect Dis ; 21(1): 194, 2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33607958

RESUMO

BACKGROUND: Long-lasting insecticidal nets (LLINs) are currently the primary method of malaria control in sub-Saharan Africa and have contributed to a significant reduction in malaria burden over the past 15 years. However, this progress is threatened by the wide-scale selection of insecticide-resistant malaria vectors. It is, therefore, important to accelerate the generation of evidence for new classes of LLINs. METHODS: This protocol presents a three-arm superiority, single-blinded, cluster randomized controlled trial to evaluate the impact of 2 novel dual-active ingredient LLINs on epidemiological and entomological outcomes in Benin, a malaria-endemic area with highly pyrethroid-resistant vector populations. The study arms consist of (i) Royal Guard® LLIN, a net combining a pyrethroid (alpha-cypermethrin) plus an insect growth regulator (pyriproxyfen), which in the adult female is known to disrupt reproduction and egg fertility; (ii) Interceptor G2® LLIN, a net incorporating two adulticides (alpha-cypermethrin and chlorfenapyr) with different modes of action; and (iii) the control arm, Interceptor® LLIN, a pyrethroid (alpha-cypermethrin) only LLIN. In all arms, one net for every 2 people will be distributed to each household. Sixty clusters were identified and randomised 1:1:1 to each study arm. The primary outcome is malaria case incidence measured over 24 months through active case detection in a cohort of 25 children aged 6 months to 10 years, randomly selected from each cluster. Secondary outcomes include 1) malaria infection prevalence (all ages) and prevalence of moderate to severe anaemia in children under 5 years old, measured at 6 and 18 months post-intervention; 2) entomological indices measured every 3 months using human landing catches over 24 months. Insecticide resistance intensity will also be monitored over the study period. DISCUSSION: This study is the second cluster randomised controlled trial to evaluate the efficacy of these next-generation LLINs to control malaria transmitted by insecticide-resistant mosquitoes. The results of this study will form part of the WHO evidence-based review to support potential public health recommendations of these nets and shape malaria control strategies of sub-Saharan Africa for the next decade. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03931473 , registered on 30 April 2019.


Assuntos
Resistência a Inseticidas/efeitos dos fármacos , Mosquiteiros Tratados com Inseticida , Malária/prevenção & controle , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , Animais , Benin/epidemiologia , Humanos , Incidência , Inseticidas/farmacologia , Malária/epidemiologia , Malária/transmissão , Prevalência , Piretrinas/farmacologia , Piridinas/farmacologia
7.
PLoS Negl Trop Dis ; 15(2): e0009173, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33600413

RESUMO

BACKGROUND: As an invasive mosquito species in the United States, Aedes albopictus is a potential vector of arboviruses including dengue, chikungunya, and Zika, and may also be involved in occasional transmission of other arboviruses such as West Nile, Saint Louis encephalitis, eastern equine encephalitis, and La Crosse viruses. Aedes albopictus feeds on a wide variety of vertebrate hosts, wild and domestic, as well as humans. METHODOLOGY/PRINCIPAL FINDINGS: In order to investigate blood feeding patterns of Ae. albopictus, engorged specimens were collected from a variety of habitat types using the Centers for Disease Control and Prevention light traps, Biogents Sentinel 2 traps, and modified Reiter gravid traps in southeast Virginia. Sources of blood meals were determined by the analysis of mitochondrial cytochrome b gene sequences amplified in PCR assays. Our aims were to quantify degrees of Ae. albopictus interactions with vertebrate hosts as sources of blood meals, investigate arboviral infection status, assess the influence of key socioecological conditions on spatial variability in blood feeding, and investigate temporal differences in blood feeding by season. Analysis of 961 engorged specimens of Ae. albopictus sampled between 2017-2019 indicated that 96%, 4%, and less than 1% obtained blood meals from mammalian, reptilian, and avian hosts, respectively. Domestic cats were the most frequently identified (50.5%) hosts followed by Virginia opossums (17.1%), white-tailed deer (12.2%), and humans (7.3%), together representing 87.1% of all identified blood hosts. We found spatial patterns in blood feeding linked to socioecological conditions and seasonal shifts in Ae. albopictus blood feeding with implications for understanding human biting and disease risk. In Suffolk Virginia in areas of lower human development, the likelihood of human blood feeding increased as median household income increased and human blood feeding was more likely early in the season (May-June) compared to later (July-October). Screening of the head and thorax of engorged Ae. albopictus mosquitoes by cell culture and RT-PCR resulted in a single isolate of Potosi virus. CONCLUSION AND SIGNIFICANCE: Understanding mosquito-host interactions in nature is vital for evaluating vectorial capacity of mosquitoes. These interactions with competent reservoir hosts support transmission, maintenance, and amplification of zoonotic agents of human diseases. Results of our study in conjunction with abundance in urban/suburban settings, virus isolation from field-collected mosquitoes, and vector competence of Ae. albopictus, highlight the potential involvement of this species in the transmission of a number of arboviruses such as dengue, chikungunya, and Zika to humans. Limited interaction with avian hosts suggests that Ae. albopictus is unlikely to serve as a bridge vector of arboviruses such as West Nile and eastern equine encephalitis in the study region, but that possibility cannot be entirely ruled out.


Assuntos
Aedes/fisiologia , Aedes/virologia , Arbovírus/isolamento & purificação , Comportamento Alimentar , Animais , Infecções por Arbovirus , Aves , Sangue/virologia , Humanos , Mamíferos , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Tartarugas , Virginia
8.
Parasit Vectors ; 14(1): 17, 2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33407790

RESUMO

BACKGROUND: The sibling species of the malaria mosquito, Anopheles gambiae (sensu stricto) and Anopheles coluzzii co-exist in many parts of West Africa and are thought to have recently diverged through a process of ecological speciation with gene flow. Divergent larval ecological adaptations, resulting in Genotype-by-Environment (G × E) interactions, have been proposed as important drivers of speciation in these species. In West Africa, An. coluzzii tends to be associated with permanent man-made larval habitats such as irrigated rice fields, which are typically more eutrophic and mineral and ammonia-rich than the temporary rain pools exploited by An. gambiae (s.s.) METHODS: To highlight G × E interactions at the larval stage and their possible role in ecological speciation of these species, we first investigated the effect of exposure to ammonium hydroxide and water mineralisation on larval developmental success. Mosquito larvae were exposed to two water sources and increasing ammonia concentrations in small containers until adult emergence. In a second experiment, larval developmental success was compared across two contrasted microcosms to highlight G × E interactions under conditions such as those found in the natural environment. RESULTS: The first experiment revealed significant G × E interactions in developmental success and phenotypic quality for both species in response to increasing ammonia concentrations and water mineralisation. The An. coluzzii strain outperformed the An. gambiae (s.s.) strain under limited conditions that were closer to more eutrophic habitats. The second experiment revealed divergent crisscrossing reaction norms in the developmental success of the sibling species in the two contrasted larval environments. As expected, An. coluzzii had higher emergence rates in the rice paddy environment with emerging adults of superior phenotypic quality compared to An. gambiae (s.s.), and vice versa, in the rain puddle environment. CONCLUSIONS: Evidence for such G × E interactions lends support to the hypothesis that divergent larval adaptations to the environmental conditions found in man-made habitats such as rice fields in An. coluzzii may have been an important driver of its ecological speciation.


Assuntos
Amônia/metabolismo , Anopheles/fisiologia , Adaptação Fisiológica , África Ocidental , Animais , Bioensaio/métodos , Evolução Biológica , Produtos Agrícolas , Ecossistema , Eutrofização , Especiação Genética , Laboratórios , Larva/fisiologia , Malária/transmissão , Mosquitos Vetores/fisiologia , Água/química
9.
Parasit Vectors ; 14(1): 21, 2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33407798

RESUMO

BACKGROUND: Aedes aegypti control programs have failed to restrain mosquito population expansion and, consequently, the spread of diseases such as dengue, Zika, and Chikungunya. Wolbachia infection of mosquitoes is a new and promising complementary tool for the control of arbovirus transmission. The use of Wolbachia-infected mosquitoes, mass reared using human blood, is currently being tested in several countries. However, the use of human blood for mass rearing mosquitoes, and thus expansion of this strategy, is problematic. With the aim of overcoming this problem, we tested the effect of different types of blood source on the fitness parameters of female Ae. aegypti and the Wolbachia titer over generations to be able to guarantee the suitability of an alternative source to human blood for mass rearing Wolbachia-infected mosquitoes. METHODS: We investigated and compared essential parameters of the vector capacity of laboratory strains of Ae. aegypti with and without Wolbachia that fed on blood of different types of host (human, guinea pig, and mouse). The parameters analyzed were fecundity, fertility, pupation dynamics, and adult survival. Also, we tested whether it is possible to maintain mosquitoes with Wolbachia on mouse blood over generations without losing the bacterium titer. RESULTS: The average number of eggs per female, egg viability and pupation dynamics in the Wolbachia-infected mosquito (wMelBr) strain were similar, regardless of the blood source. The F1 progenies of females that fed on mouse blood or human blood were analyzed. The longevity of males was lower than that of females. F1 female survival differed depending on the presence of Wolbachia in the mother. In subsequent generations analyzed up until F35, the relative Wolbachia density was even higher when mosquitoes fed on mouse blood in comparison to human blood. CONCLUSIONS: Taken together, our results provide no evidence that the different types of blood influenced the fitness of the Wolbachia-infected mosquitoes. The presence of the bacterium in the colonies of Wolbachia-infected Ae. aegypti after 35 generations under the conditions evaluated indicates that they can be maintained on mouse blood. Based on these results, we show that it is possible to use mouse blood to feed female mosquitoes when using human blood for this purpose is problematic.


Assuntos
Aedes , Sangue , Wolbachia , Aedes/crescimento & desenvolvimento , Aedes/microbiologia , Aedes/fisiologia , Ração Animal , Animais , Infecções por Arbovirus/transmissão , Vetores de Doenças , Fertilidade , Cobaias , Humanos , Controle de Insetos , Longevidade , Camundongos , Mosquitos Vetores/microbiologia , Mosquitos Vetores/fisiologia , Controle Biológico de Vetores/métodos , Reprodução
10.
PLoS One ; 16(1): e0245750, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33507908

RESUMO

BACKGROUND: While malaria transmission in Africa still happens primarily inside houses, there is a substantial proportion of Anopheles mosquitoes that bite or rest outdoors. This situation may compromise the performance of indoor insecticidal interventions such as insecticide-treated nets (ITNs). This study investigated the distribution of malaria mosquitoes biting or resting outside dwellings in three low-altitude villages in south-eastern Tanzania. The likelihood of malaria infections outdoors was also assessed. METHODS: Nightly trapping was done outdoors for 12 months to collect resting mosquitoes (using resting bucket traps) and host-seeking mosquitoes (using odour-baited Suna® traps). The mosquitoes were sorted by species and physiological states. Pooled samples of Anopheles were tested to estimate proportions infected with Plasmodium falciparum parasites, estimate proportions carrying human blood as opposed to other vertebrate blood and identify sibling species in the Anopheles gambiae complex and An. funestus group. Environmental and anthropogenic factors were observed and recorded within 100 meters from each trapping positions. Generalised additive models were used to investigate relationships between these variables and vector densities, produce predictive maps of expected abundance and compare outcomes within and between villages. RESULTS: A high degree of fine-scale heterogeneity in Anopheles densities was observed between and within villages. Water bodies covered with vegetation were associated with 22% higher densities of An. arabiensis and 51% lower densities of An. funestus. Increasing densities of houses and people outdoors were both associated with reduced densities of An. arabiensis and An. funestus. Vector densities were highest around the end of the rainy season and beginning of the dry seasons. More than half (14) 58.3% of blood-fed An. arabiensis had bovine blood, (6) 25% had human blood. None of the Anopheles mosquitoes caught outdoors was found infected with malaria parasites. CONCLUSION: Outdoor densities of both host-seeking and resting Anopheles mosquitoes had significant heterogeneities between and within villages, and were influenced by multiple environmental and anthropogenic factors. Despite the high Anopheles densities outside dwellings, the substantial proportion of non-human blood-meals and absence of malaria-infected mosquitoes after 12 months of nightly trapping suggests very low-levels of outdoor malaria transmission in these villages.


Assuntos
Distribuição Animal , Anopheles/fisiologia , Comportamento Alimentar , Mordeduras e Picadas de Insetos/epidemiologia , Mosquitos Vetores/fisiologia , Altitude , Animais , Biomassa , Feminino , Habitação , Humanos , Masculino , População Rural , Tanzânia
11.
PLoS Comput Biol ; 17(1): e1008627, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33465065

RESUMO

Heterogeneous exposure to mosquitoes determines an individual's contribution to vector-borne pathogen transmission. Particularly for dengue virus (DENV), there is a major difficulty in quantifying human-vector contacts due to the unknown coupled effect of key heterogeneities. To test the hypothesis that the reduction of human out-of-home mobility due to dengue illness will significantly influence population-level dynamics and the structure of DENV transmission chains, we extended an existing modeling framework to include social structure, disease-driven mobility reductions, and heterogeneous transmissibility from different infectious groups. Compared to a baseline model, naïve to human pre-symptomatic infectiousness and disease-driven mobility changes, a model including both parameters predicted an increase of 37% in the probability of a DENV outbreak occurring; a model including mobility change alone predicted a 15.5% increase compared to the baseline model. At the individual level, models including mobility change led to a reduction of the importance of out-of-home onward transmission (R, the fraction of secondary cases predicted to be generated by an individual) by symptomatic individuals (up to -62%) at the expense of an increase in the relevance of their home (up to +40%). An individual's positive contribution to R could be predicted by a GAM including a non-linear interaction between an individual's biting suitability and the number of mosquitoes in their home (>10 mosquitoes and 0.6 individual attractiveness significantly increased R). We conclude that the complex fabric of social relationships and differential behavioral response to dengue illness cause the fraction of symptomatic DENV infections to concentrate transmission in specific locations, whereas asymptomatic carriers (including individuals in their pre-symptomatic period) move the virus throughout the landscape. Our findings point to the difficulty of focusing vector control interventions reactively on the home of symptomatic individuals, as this approach will fail to contain virus propagation by visitors to their house and asymptomatic carriers.


Assuntos
Dengue/epidemiologia , Dengue/transmissão , Surtos de Doenças/estatística & dados numéricos , Mosquitos Vetores , Animais , Biologia Computacional , Dengue/prevenção & controle , Dengue/virologia , Vírus da Dengue , Feminino , Humanos , Modelos Estatísticos , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Dinâmica Populacional
12.
PLoS Negl Trop Dis ; 15(1): e0008915, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33406161

RESUMO

The adult females of Aedes aegypti mosquitoes are facultative hematophagous insects but they are unable to feed on blood right after pupae emergence. The maturation process that takes place during the first post-emergence days, hereafter named hematophagic and gonotrophic capacitation, comprises a set of molecular and physiological changes that prepare the females for the first gonotrophic cycle. Notwithstanding, the molecular bases underlying mosquito hematophagic and gonotrophic capacitation remain obscure. Here, we investigated the molecular and biochemical changes in adult Ae. aegypti along the first four days post-emergence, prior to a blood meal. We performed a RNA-Seq analysis of the head and body, comparing male and female gene expression time courses. A total of 811 and 203 genes were differentially expressed, respectively in the body and head, and both body parts showed early, mid, and late female-specific expression profiles. Female-specific up-regulation of genes involved in muscle development and the oxidative phosphorylation pathway were remarkable features observed in the head. Functional assessment of mitochondrial oxygen consumption in heads showed a gradual increase in respiratory capacity and ATP-linked respiration as a consequence of induced mitochondrial biogenesis and content over time. This pattern strongly suggests that boosting oxidative phosphorylation in heads is a required step towards blood sucking habit. Several salivary gland genes, proteases, and genes involved in DNA replication and repair, ribosome biogenesis, and juvenile hormone signaling were up-regulated specifically in the female body, which may reflect the gonotrophic capacitation. This comprehensive description of molecular and biochemical mechanisms of the hematophagic and gonotrophic capacitation in mosquitoes unravels potentially new targets for vector control.


Assuntos
Aedes/fisiologia , Comportamento Alimentar/fisiologia , Transcriptoma , Animais , Replicação do DNA , Feminino , Expressão Gênica , Humanos , Masculino , Mitocôndrias/metabolismo , Mosquitos Vetores/fisiologia , Oxigênio/metabolismo , Fosforilação
13.
Proc Natl Acad Sci U S A ; 117(52): 32848-32856, 2020 12 29.
Artigo em Inglês | MEDLINE | ID: mdl-33372129

RESUMO

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.


Assuntos
Culicidae/fisiologia , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , Paladar , Animais , Comportamento Animal , Culicidae/metabolismo , Humanos , Mosquitos Vetores/metabolismo
14.
PLoS One ; 15(12): e0244447, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33373422

RESUMO

Rapidly increasing pyrethroid insecticide resistance and changes in vector biting and resting behavior pose serious challenges in malaria control. Mosquito repellents, especially spatial repellents, have received much attention from industry. We attempted to simulate interactions between mosquitoes and repellents using a machine learning method, the Self-Propelled Particle (SPP) model, which we modified to include attractiveness/repellency effects. We simulated a random walk scenario and scenarios with insecticide susceptible/resistant mosquitoes against repellent alone and against repellent plus attractant (to mimic a human host). Simulation results indicated that without attractant/repellent, mosquitoes would fly anywhere in the cage at random. With attractant, all mosquitoes were attracted to the source of the odor by the end. With repellent, all insecticide-susceptible mosquitoes eventually moved to the corner of the cage farthest from the repellent release point, whereas, a high proportion of highly resistant mosquitoes might reach the attractant release point (the human) earlier in the simulation. At fixed concentration, a high proportion of mosquitoes could be able to reach the host when the relative repellency efficacy (compare to attractant efficacy) was <1, whereas, no mosquitoes reached the host when the relative repellency efficacy was > 1. This result implies that repellent may not be sufficient against highly physiologically insecticide resistant mosquitoes, since very high concentrations of repellent are neither practically feasible nor cost-effective.


Assuntos
Anopheles/fisiologia , Comportamento de Busca por Hospedeiro/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Malária/prevenção & controle , Mosquitos Vetores/fisiologia , Animais , Anopheles/efeitos dos fármacos , Simulação por Computador , Voo Animal/efeitos dos fármacos , Voo Animal/fisiologia , Comportamento de Busca por Hospedeiro/fisiologia , Humanos , Resistência a Inseticidas/fisiologia , Inseticidas/farmacologia , Aprendizado de Máquina , Modelos Biológicos , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , Odorantes , Piretrinas/farmacologia
15.
PLoS Negl Trop Dis ; 14(12): e0008971, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33338046

RESUMO

Aedes aegypti is a vector of dengue, chikungunya, and Zika viruses. Current vector control strategies such as community engagement, source reduction, and insecticides have not been sufficient to prevent viral outbreaks. Thus, interest in novel strategies involving genetic engineering is growing. Female mosquitoes rely on flight to mate with males and obtain a bloodmeal from a host. We hypothesized that knockout of genes specifically expressed in female mosquitoes associated with the indirect flight muscles would result in a flightless female mosquito. Using CRISPR-Cas9 we generated loss-of-function mutations in several genes hypothesized to control flight in mosquitoes, including actin (AeAct-4) and myosin (myo-fem) genes expressed specifically in the female flight muscle. Genetic knockout of these genes resulted in 100% flightless females, with homozygous males able to fly, mate, and produce offspring, albeit at a reduced rate when compared to wild type males. Interestingly, we found that while AeAct-4 was haplosufficient, with most heterozygous individuals capable of flight, this was not the case for myo-fem, where about half of individuals carrying only one intact copy could not fly. These findings lay the groundwork for developing novel mechanisms of controlling Ae. aegypti populations, and our results suggest that this mechanism could be applicable to other vector species of mosquito.


Assuntos
Aedes/genética , Sistemas CRISPR-Cas , Inseticidas/farmacologia , Controle de Mosquitos , Mosquitos Vetores/genética , Infecção por Zika virus/prevenção & controle , Zika virus/fisiologia , Aedes/fisiologia , Aedes/virologia , Animais , Feminino , Voo Animal , Técnicas de Inativação de Genes , Humanos , Masculino , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Fenótipo , Infecção por Zika virus/transmissão , Infecção por Zika virus/virologia
16.
Trends Parasitol ; 36(11): 888-897, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32952061

RESUMO

Sleep is a phenomenon conserved across the animal kingdom, where studies on Drosophila melanogaster have revealed that sleep phenotypes and molecular underpinnings are similar to those in mammals. However, little is known about sleep in blood-feeding arthropods, which have a critical role in public health as disease vectors. Specifically, sleep studies in mosquitoes are lacking despite considerable focus on how circadian processes, which have a central role in regulating sleep/wake cycles, impact activity, feeding, and immunity. Here, we review observations which suggest that sleep-like states likely occur in mosquitoes and discuss the potential role of sleep in relation to mosquito biology and their ability to function as disease vectors.


Assuntos
Ritmo Circadiano/fisiologia , Culicidae/fisiologia , Mosquitos Vetores/fisiologia , Sono/fisiologia , Doenças Transmitidas por Vetores/parasitologia , Doenças Transmitidas por Vetores/transmissão , Animais , Culicidae/genética , Mosquitos Vetores/genética , Sono/genética
17.
PLoS One ; 15(9): e0239636, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32976497

RESUMO

Animals with complex life cycles have traits related to oviposition and juvenile survival that can respond to environmental factors in similar or dissimilar ways. We examined the preference-performance hypothesis (PPH), which states that females lacking parental care select juvenile habitats that maximize fitness, for two ubiquitous mosquito species, Aedes albopictus and Culex quinquefasciatus. Specifically, we examined if environmental factors known to affect larval abundance patterns in the field played a role in the PPH for these species. We first identified important environmental factors from a field survey that predicted larvae across different spatial scales. We then performed two experiments, the first testing the independent responses of oviposition and larval survival to these environmental factors, followed by a combined experiment where initial oviposition decisions were allowed to affect larval life history measures. We used path analysis for this last experiment to determine important links among factors in explaining egg numbers, larval mass, development time, and survival. For separate trials, Aedes albopictus displayed congruence between oviposition and larval survival, however C. quinquefasciatus did not. For the combined experiment path analysis suggested neither species completely fit predictions of the PPH, with density dependent effects of initial egg number on juvenile performance in A. albopictus. For these species the consequences of female oviposition choices on larval performance do not appear to fit expectations of the PPH.


Assuntos
Adaptação Fisiológica , Comportamento Animal , Mosquitos Vetores/fisiologia , Oviposição , Aedes/fisiologia , Animais , Culex/fisiologia , Ecossistema , Feminino , Larva/fisiologia , Especificidade da Espécie
18.
PLoS Negl Trop Dis ; 14(9): e0008531, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32911504

RESUMO

Pathogens may manipulate their human and mosquito hosts to enhance disease transmission. Dengue, caused by four viral serotypes, is the fastest-growing transmissible disease globally resulting in 50-100 million infections annually. Transmission of the disease relies on the interaction between humans and the vector Aedes aegypti and is largely dependent on the odor-mediated host seeking of female mosquitoes. In this study, we use activity monitors to demonstrate that dengue virus-1 affects the locomotion and odor-mediated behavior of Ae. aegypti, reflecting the progression of infection within the mosquito. Mosquitoes 4-6 days post-infection increase locomotion, but do not alter their odor-driven host-seeking response. In contrast, females 14-16 days post-infection are less active, yet more sensitive to human odors as assessed by behavioral and electrophysiological assays. Such an increase in physiological and behavioral sensitivity is reflected by the antennal-specific increase in abundance of neural signaling transcripts in 14 days post-infection females, as determined by transcriptome analysis. This suggests that the sensitivity of the mosquito peripheral olfactory system is altered by the dengue virus by enhancing the overall neural responsiveness of the antenna, rather than the selective regulation of chemosensory-related genes. Our study reveals that dengue virus-1 enhances vector-related behaviors in the early stages post-infection that aid in avoiding predation and increasing spatial exploration. On the other hand, at the later stages of infection, the virus enhances the host-seeking capacity of the vector, thereby increasing the risk of virus transmission. A potential mechanism is discussed.


Assuntos
Aedes/virologia , Dengue , Comportamento de Busca por Hospedeiro , Aedes/genética , Aedes/metabolismo , Aedes/fisiologia , Animais , Antenas de Artrópodes/fisiologia , Comportamento Animal , Vírus da Dengue/fisiologia , Feminino , Perfilação da Expressão Gênica , Humanos , Locomoção , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia
19.
PLoS Negl Trop Dis ; 14(9): e0008705, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32986704

RESUMO

Over the past three decades, Europe has witnessed an increased spread of invasive aedine mosquito species, most notably Aedes albopictus, a key vector of chikungunya, dengue and Zika virus. While its distribution in southern Europe is well documented, its dispersal modes across the Alps remain poorly investigated, preventing a projection of future scenarios beyond its current range in order to target mosquito control. To monitor the presence and frequency of invasive Aedes mosquitoes across and beyond the Alps we set oviposition and BG-Sentinel traps at potential points of entry with a focus on motorway service areas across Switzerland. We placed the traps from June to September and controlled them for the presence of mosquitoes every other week between 2013 and 2018. Over the six years of surveillance we identified three invasive Aedes species, including Ae. albopictus, Ae. japonicus and Ae. koreicus. Based on the frequency and distribution patterns we conclude that Ae. albopictus and Ae. koreicus are being passively spread primarily along the European route E35 from Italy to Germany, crossing the Alps, while Ae. japonicus has been expanding its range from northern Switzerland across the country most likely through active dispersal.


Assuntos
Aedes/classificação , Aedes/fisiologia , Monitoramento Epidemiológico , Mosquitos Vetores/fisiologia , Aedes/virologia , Animais , Europa (Continente) , Feminino , Espécies Introduzidas , Itália , Controle de Mosquitos/instrumentação , Oviposição/fisiologia , Suíça , Zika virus
20.
PLoS Negl Trop Dis ; 14(9): e0008576, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32881865

RESUMO

BACKGROUND: The ability of cluster-randomized trials to capture mass or indirect effects is one reason for their increasing use to test interventions against vector-borne diseases such as malaria and dengue. For the same reason, however, the independence of clusters may be compromised if the distances between clusters is too small to ensure independence. In other words they may be subject to spillover effects. METHODS: We distinguish two types of spatial spillover effect: between-cluster dependence in outcomes, or spillover dependence; and modification of the intervention effect according to distance to the intervention arm, or spillover indirect effect. We estimate these effects in trial of insecticide-treated materials against the dengue mosquito vector, Aedes aegypti, in Venezuela, the endpoint being the Breteau index. We use a novel random effects Poisson spatial regression model. Spillover dependence is incorporated via an orthogonalized intrinsic conditional autoregression (ICAR) model. Spillover indirect effects are incorporated via the number of locations within a certain radius, set at 200m, that are in the intervention arm. RESULTS: From the model with ICAR spatial dependence, and the degree of surroundedness, the intervention effect is estimated as 0.74-favouring the intervention-with a 95% credible interval of 0.34 to 1.69. The point estimates are stronger with increasing surroundedness within intervention locations. CONCLUSION: In this trial there is some evidence of a spillover indirect effect of the intervention, with the Breteau index tending to be lower in locations which are more surrounded by locations in the intervention arm.


Assuntos
Aedes/efeitos dos fármacos , Inseticidas/farmacologia , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , Aedes/fisiologia , Animais , Dengue/transmissão , Humanos , Mosquitos Vetores/fisiologia , Análise Espacial , Venezuela
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