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1.
J Insect Sci ; 20(1)2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31916580

RESUMO

The western tree hole mosquito, Aedes sierrensis (Ludlow), is a common nuisance mosquito and vector of Dirofilaria immitis (Leidy), the etiologic agent of dog heartworm, in western North America. Here, we compare weekly mosquito collections made with Mosquito Magnet (MM) traps, Biogents Sentinel (BGS) traps, and Biogents Bowl (BGS Bowl) traps set in Salt Lake City, UT, from the start of June to mid-August 2017. We found the number of mosquitoes decreased with rainfall and temperature independently of trap type. The highest number of mosquitoes were caught by BGS traps baited with carbon dioxide (CO2) and BG lure, which collected 62% (n = 422) of all mosquitoes, followed by the MM at 31% (n = 213), and both the BGS and BG Bowl with BG lure had 3.5% (n = 24) each. Aedes sierrensis females were caught weekly at similar densities (mean ±â€…SD) in BGS with CO2 and lure (1.17 ±â€…2.93) and the MM (1.17 ±â€…2.66) traps during the study period. Given that BGS with CO2 and lure traps have several operational advantages over MM traps, including a quicker setup, smaller size, and lower cost, we consider BGS with CO2 and lure traps as the best suited surveillance tool to detect and remove Ae. sierrensis in the western United States and similar settings throughout North America.


Assuntos
Aedes , Controle de Mosquitos/métodos , Mosquitos Vetores , Vigilância da População/métodos , Animais , Dirofilaria immitis , Feminino , Masculino , Mosquitos Vetores/fisiologia , Dinâmica Populacional , Utah
3.
Acta Trop ; 201: 105179, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31539525

RESUMO

Natural products have proven to be an immeasurable source of bioactive compounds. The exceptional biodiversity encountered in Amazonia, alongside a rich entomofauna and frequent interactions with various herbivores is the crucible of a promising chemodiversity. This prompted us to search for novel botanical insecticides in French Guiana. As this French overseas department faces severe issues linked to insects, notably the strong incidence of vector-borne infectious diseases, we decided to focus our research on products able to control the mosquito Aedes aegypti. We tested 452 extracts obtained from 85 species originating from 36 botanical families and collected in contrasted environments against an Ae. aegypti laboratory strain susceptible to all insecticides, and a natural population resistant to both pyrethroid and organophosphate insecticides collected in Cayenne for the most active of them. Eight species (Maytenus oblongata Reissek, Celastraceae; Costus erythrothyrsus Loes., Costaceae; Humiria balsamifera Aubl., Humiriaceae; Sextonia rubra (Mez) van der Werff, Lauraceae; Piper hispidum Sw., Piperaceae; Laetia procera (Poepp.) Eichl., Salicaceae; Matayba arborescens (Aubl.) Radlk., Sapindaceae; and Cupania scrobitulata Rich., Sapindaceae) led to extracts exhibiting more than 50% larval mortality after 48 h of exposition at 100 µg/mL against the natural population and were considered active. Selectivity and phytochemistry of these extracts were therefore investigated and discussed, and some active compounds highlighted. Multivariate analysis highlighted that solvents, plant tissues, plant family and location had a significant effect on mortality while light, available resources and vegetation type did not. Through this case study we highlighted that plant defensive chemistry mechanisms are crucial while searching for novel insecticidal products.


Assuntos
Aedes , Inseticidas/farmacologia , Extratos Vegetais/farmacologia , Animais , Guiana Francesa , Larva/efeitos dos fármacos , Controle de Mosquitos
4.
Sci Total Environ ; 700: 134443, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31655455

RESUMO

Worldwide, billions of people are at risk from viruses, parasites and bacteria transmitted by mosquitoes, ticks, fleas and other vectors. Over exploitation of chemical pesticides to overcome the mosquito borne diseases led to detrimental effects on environment and human health. The present research aims to explore bio-fabrication of metal silver nanomaterials using Rhazya stricta extract against deadly mosquito vectors and microbial pathogens. The phytochemical profile of the R. stricta extracts was studied by HPLC-MS and 1H NMR. Further, confirmation of the bio-fabricated silver nanoparticles (AgNPs) was carried out by UV-vis spectroscopy and characterization through FTIR, TEM, EDX, and XRD analyses. The R. stricta-fabricated AgNPs showed acute toxicity on key mosquito vectors from two different country (India and Kingdom of Saudi Arabia, KSA) strains, notably, with LC50 values of 10.57, 11.89 and 12.78 µg/ml on malarial, dengue and filarial key Indian strains of mosquito vectors, respectively, and 30.66 and 38.39 µg/ml on KSA strains of Aedes aegypti and Culex pipiens, respectively. In mosquito adulticidal activity, R. stricta extract alone exhibited LC50 values ranging from 304.34 to 382.45 µg/ml against Indian strains and from 738.733 to 886.886 against Saudi Arabian strains, while AgNPs LC50 boosted from 9.52 to 12.16 µg/ml and from 30.66 to 38.39 µg/ml, respectively. Moreover, it was noticed that at low concentration the tested AgNPs showed high growth retardation of important pathogenic bacteria such as Bacillus subtilis, Klebsiella pneumoniae and Salmonella typhi with inhibition zone diameters from 11.86 to 22.92 mm. In conclusion, the present study highlighted that R. stricta-fabricated AgNPs could be a lead material for the management of mosquito vector and microbial pathogens control.


Assuntos
Anti-Infecciosos/química , Apocynaceae , Inseticidas/química , Nanopartículas Metálicas/química , Mosquitos Vetores/efeitos dos fármacos , Extratos Vegetais/química , Prata/química , Anti-Infecciosos/toxicidade , Índia , Inseticidas/toxicidade , Dose Letal Mediana , Controle de Mosquitos/métodos , Extratos Vegetais/toxicidade
5.
Rev Environ Contam Toxicol ; 252: 131-171, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31463624

RESUMO

Anurans from the genus Xenopus have long been used as standard testing organisms and occur naturally in tropical and sub-tropical areas where malaria vector control pesticides are actively used. However, literature on the toxic effects of these pesticides is limited. This review analyses the available data pertaining to both Xenopus and the pesticides used for malaria vector control in order to determine the pesticides that have the greatest potential to influence amphibian health while also identifying gaps in literature that need to be addressed. Amphibian diversity has shown the fastest decline of any group, yet there are still voids in our understanding of how this is happening. The lack of basic toxicity data on amphibians with regard to pesticides is an issue that needs to be addressed in order to improve effectiveness of amphibian conservation strategies. Meta-analyses performed in this review show that, at current usage, with the available acute toxicity literature, the pyrethroid pesticide group could hold the highest potential to cause acute toxicity to Xenopus sp. in relation to the other MVCPs discussed, but the lack of data cripples the efficacy with which meta-analyses can be performed and conclusions made from such analyses. Several studies have shown that DDT accumulates in Xenopus sp. from malaria vector control areas, but accumulation of other MVCPs in frogs is still largely unknown. Through this review we hope to encourage future research into the field of amphibian ecotoxicology and to promote the use of the Xenopus standard model in order to build comprehensive datasets that may be used in amphibian conservation.


Assuntos
Ecotoxicologia , Poluentes Ambientais/toxicidade , Malária , Controle de Mosquitos , Mosquitos Vetores , Praguicidas/toxicidade , Animais , Anopheles , Xenopus , Xenopus laevis
6.
Parasit Vectors ; 12(1): 522, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31690332

RESUMO

BACKGROUND: Insecticides formulated into products that target Anopheles mosquitos have had an immense impact on reducing malaria cases in Africa. However, resistance to currently used insecticides is spreading rapidly and there is an urgent need for alternative public health insecticides. Potential new insecticides must be screened against a range of characterized mosquito strains to identify potential resistance liabilities. The Liverpool School of Tropical Medicine maintains three susceptible and four resistant Anopheles strains that are widely used for screening for new insecticides. The properties of these strains are described in this paper. METHODS: WHO tube susceptibility bioassays were used for colony selection and to screen for resistance to the major classes of public health insecticides. Topical and tarsal contact bioassays were used to produce dose response curves to assess resistance intensity. Bioassays with the synergist piperonyl butoxide were also performed. Taqman™ assays were used to screen for known target site resistance alleles (kdr and ace-1). RT-qPCR was used to quantify expression of genes associated with pyrethroid resistance. RESULTS: Pyrethroid selection pressure has maintained resistance to this class in all four resistant strains. Some carbamate and organophosphate resistance has been lost through lack of exposure to these insecticide classes. The Anopheles gambiae (sensu lato) strains, VK7 2014, Banfora M and Tiassalé 13 have higher levels of pyrethroid resistance than the An. funestus FUMOZ-R strain. Elevated expression of P450s is found in all four strains and the 1014F kdr mutation is present in all three An. gambiae strains at varying frequencies. Tarsal contact data and overexpression of CYP4G16 and SAP2 suggest penetration barriers and/or sequestration also confer resistance in Banfora M. CONCLUSIONS: Continual selection with deltamethrin has maintained a stable pyrethroid-resistant phenotype over many generations. In conjunction with a standardized rearing regime, this ensures quality control of strains over time allowing for robust product comparison and selection of optimal products for further development. The identification of multiple mechanisms underpinning insecticide resistance highlights the importance of screening new compounds against a range of mosquito strains.


Assuntos
Anopheles/classificação , Inseticidas , Malária/prevenção & controle , Controle de Mosquitos/métodos , Mosquitos Vetores/classificação , Análise de Variância , Animais , Anopheles/genética , Bioensaio , Sistema Enzimático do Citocromo P-450/análise , Sistema Enzimático do Citocromo P-450/genética , DNA/genética , DNA/isolamento & purificação , Relação Dose-Resposta a Droga , Feminino , Técnicas de Genotipagem , Resistência a Inseticidas , Malária/transmissão , Controle de Mosquitos/normas , Mosquitos Vetores/genética , Mutação Puntual , Piretrinas
7.
Malar J ; 18(1): 347, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31615576

RESUMO

BACKGROUND: Gene drive mosquitoes have been proposed as a possible means to reduce the transmission of malaria in Africa. Because this technology has no prior use-history at this time, environmental risk assessments for gene drive mosquitoes will benefit from problem formulation-an organized and ordered process to identify protection goals and potential pathways to harm to the environment, or animal or human health. Recognizing this need, the New Partnership for Africa's Development (NEPAD), with support from African and international partners, organized four regional consultative workshops in Africa to initiate this process. METHODS: The workshops were attended by a diverse set of participants and stakeholders, including scientists, ethicists, health professionals, government regulators in the fields of environment health and biosafety as well government policymakers, who met for 4 days to deliberate on protection goals and pathways relevant to the use of gene drive mosquitoes for malaria control. The goal of the workshops was not to produce a comprehensive and detailed environmental risk assessment of gene drive mosquitoes, but rather to introduce problem formulation as a tool to the stakeholder community, and to serve as a starting point for conducting systematic environmental risk assessments in the future, identifying protection goals related to gene drive mosquitoes that are particular to African stakeholders. RESULTS: Participants in the workshops frequently identified human health and biodiversity as being relevant broad protection goals. Results of the deliberations provide insight into the concerns of African participants at an early stage in the development of gene drive organism/products that should be instructive to developers using this technology. CONCLUSIONS: In general, the African participants of the consultations had a precautionary perspective with regard to environmental risk assessment of gene drive technology. As gene drive technology develops, protection goals will become further refined and candidate products will be further defined. These workshops represent only the beginning of a continuing process that will ultimately inform environmental risk assessment for gene drive mosquitoes to control malaria in Africa.


Assuntos
Anopheles/genética , Tecnologia de Impulso Genético/métodos , Controle de Mosquitos/métodos , Mosquitos Vetores/genética , África , Animais , Medição de Risco
8.
Afr Health Sci ; 19(2): 2000-2007, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31656483

RESUMO

Background: In the last five decades, dengue has emerged as one of the most important infectious diseases, following a 30-fold increase in global incidence throughout tropical and sub-tropical regions of the world. The actual numbers of dengue cases are under-reported and many cases are misclassified. Objectives: This article describes the epidemiology, pathophysiology, clinical features and management of dengue. It also explores the implications of infection with this flavivirus for Nigeria, and similar countries. Methods: The literature search for publications on dengue in West Africa was performed using PubMed, African Journals Online (AJOL), Google Scholar, Web of Science, databases and grey literature to identify all published papers regarding the topic. A snowballing strategy was adopted to identify additional publications. Results: Recent reports suggest that dengue is a growing public health problem in Nigeria, the magnitude of which needs to be more clearly defined. Nigeria, the most populous country in Africa has an abundance of the Aedes aegypti mosquito which is known to transmit dengue, Zika, as well as chikungunya (CHIKV) and West Nile viruses. Conclusion: This article provides practical suggestions for strengthening the dengue virus control programme in Nigeria. The Nigerian health system shares similarities with health systems in many other sub-Saharan countries. Therefore, the practical suggestions provided at the end of this review are likely to be applicable to many other African countries.


Assuntos
Aedes/virologia , Vírus da Dengue/isolamento & purificação , Dengue/prevenção & controle , Controle de Mosquitos , Mosquitos Vetores/virologia , Animais , Dengue/diagnóstico , Humanos , Nigéria
9.
Malar J ; 18(1): 345, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31601226

RESUMO

BACKGROUND: Malaria is a public health problem in the Brazilian Amazon region. In integrated vector management for malaria (anopheline) control, indoor residual spraying (IRS) represents one of the main tools in the basic strategy applied in the Amazonian states. It is essential to understand the residual efficacy of insecticides on different surfaces to determine spray cycles, ensure their rational use, and prevent wastage. This study aimed to evaluate the residual efficacy of six insecticide formulations used in the National Malaria Control Programme on four different types of walls in a field simulation at a "test house". METHODS: The tests were performed as a field-simulating evaluation at a "test house" built in the municipality of Macapá. Six insecticide formulations comprising four pyrethroids, a carbamate, and an organophosphate were used, and evaluated when applied on different wall surfaces: painted wood, unpainted wood, plastered cement, and unplastered cement. The insecticides were applied to the interior walls of the "test house" by a trained technician. RESULTS: In the bioassays performed with pyrethroids, deltamethrin water-dispersible granules (WG) performed particularly well, presenting residual bioefficacy of 8 months on both wood surfaces after the IRS, whereas alpha-cypermethrin suspension concentrate (SC) and etofenprox wettable powder (WP) demonstrated residual bioefficacy of 4 months on at least one of the wood surfaces; however, the pyrethroid lambda-cyhalothrin WP showed a low residual bioefficacy (< 3 months) on all tested surfaces, demonstrating its inefficiency for areas with a long transmission cycle of malaria. For the carbamate-bendiocarb WP, residual bioefficacy for 3 months was achieved only on wood surfaces. In general, the organophosphate pirimifos-methyl capsule suspension (CS) demonstrated the best result, with a mortality rate < 80% over a period of 6 months on all surfaces tested. CONCLUSION: Insecticide efficiency varies among different types of surface; therefore, a "test house" is a valuable evaluation tool. This work highlights the usefulness of associating the residual efficacy of insecticides on the surfaces commonly found in houses in endemic areas, together with knowledge about the transmission cycle duration of the transmission cycle and the insecticide susceptibility of the vector. This association helps in the decision-making for the malaria control intervention regarding.


Assuntos
Anopheles , Inseticidas , Malária/prevenção & controle , Controle de Mosquitos , Mosquitos Vetores , Animais , Brasil , Habitação
10.
Malar J ; 18(1): 335, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31570107

RESUMO

BACKGROUND: The decline in malaria cases and vectors is major milestone in fighting against malaria. The efficacy of MAGNet long-lasting insecticidal nets (MAGNet LLIN), an alpha-cypermethrin incorporated long-lasting net, with the target dose ± 25% of 5.8 g active ingredient (AI)/kg (4.35-7.25 g AI/kg) was evaluated in six veranda-trap experimental huts in Muheza, Tanzania against freely flying wild population of Anopheles funestus. METHODS: MAGNet LLINs were tested against wild, free-flying, host-seeking An. funestus mosquitoes over a period of 6 weeks (total of 36 nights in the huts). MAGNet LLIN efficacy was determined in terms of mosquito mortality, blood-feeding inhibition, deterrence, induced exiting, personal protection, and insecticidal killing over 20 washes according to WHO standardized procedures. Efficacy was compared with reference to a WHOPES recommended approved LLINs (DuraNet) and to a net conventionally treated (CTN) treated with alpha-cypermethrin at WHO-recommended dose and washed to just before cut-off point. The efficacy of MAGNet was evaluated in experimental huts against wild, free-flying, pyrethroid-resistant An. funestus. The WHO-susceptibility method was used to detect resistance in wild Anopheles exposed to 0.75% permethrin. Mosquito mortality, blood-feeding inhibition and personal protection were compared between untreated nets and standard LLINs. Blood-feeding rates were recorded and compared between the 20 times washed; blood-feeding rates between 20 times washed MAGNet LLIN and 20 times washed WHOPES-approved piperonyl butoxide (PBO)/pyrethroid were not statistically different (p > 0.05). RESULTS: The results have evidently shown that MAGNet LLIN provides similar blood-feeding inhibition, exophily, mortality, and deterrence to the standard approved LLIN, thus meeting the WHOPES criteria for blood feeding. The significantly high feeding inhibition and personal protection over pyrethroid-resistant An. funestus recorded by both unwashed and 20 times washed MAGNet compared to the unwashed DuraNet, the WHOPES-approved standard pyrethroid-only LLIN provides proof of MAGNet meeting Phase II WHOPES criteria for a LLIN. CONCLUSION: Based on this study, MAGNet has been shown to have a promising impact on protection when 20 times washed against a highly resistant population of An. funestus.


Assuntos
Anopheles , Mosquiteiros Tratados com Inseticida , Inseticidas , Lavanderia , Piretrinas , Animais , Habitação , Resistência a Inseticidas , Controle de Mosquitos/instrumentação , Tanzânia
11.
Malar J ; 18(1): 332, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31564253

RESUMO

BACKGROUND: Misuse of long-lasting insecticidal nets together with resistance of vectors to most of the insecticides for indoor residual spraying and impregnated nets threaten malaria vector control interventions, requiring search for alternative control methods. Reports have shown that Anopheles mosquitoes die when they feed on endectocidal drugs used to treat humans and animals. A study was designed to investigate the efficacy of LongRange™ (eprinomectin 5%) on laboratory reared Anopheles arabiensis fed on treated calves. METHODS: Anopheles arabiensis from insectary colony was fed on three calves treated with therapeutic dose of LongRange™ eprinomectin (1 ml/50 kg) and on non-treated three other calves as control arm. For the feeding, mosquitoes were placed in paper cups covered with nylon cloth mesh and then allowed to feed on the necks of calves. Subsequently, mosquito survival, fecundity, egg hatchability, larval development and adult emergence were recorded. Data were entered and analysed by using SPSS version 20. The Kaplan-Meier survival analysis and independent sample t-test were used. RESULTS: All mosquitoes that fed on LongRange™ Eprinomectin treated calves died within 7 days following blood ingestion. The drug also slightly affected fecundity and hatchability of An. arabiensis. CONCLUSION: Treating livestock with LongRange™ (eprinomectin 5%) may serve as a supplementary control method for zoophagic An. arabiensis.


Assuntos
Anopheles , Inseticidas/administração & dosagem , Ivermectina/análogos & derivados , Controle de Mosquitos/métodos , Animais , Bioensaio , Bovinos , Comportamento Alimentar , Fertilidade , Injeções Subcutâneas , Ivermectina/administração & dosagem , Gado , Malária/transmissão , Mosquitos Vetores
12.
BMC Public Health ; 19(1): 1318, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31638928

RESUMO

BACKGROUND: Integrated vector management (IVM) remains a key strategy in the fight against vector-borne diseases including malaria. However, impacts of the strategy should be regularly monitored based on feedback obtained through research. The objective of this study was to assess the impact of IVM for malaria control in Botor-Tolay district, southwestern Ethiopia after three years (2016-2018) of IVM implementation. METHOD: Prior to the implementation of IVM, a survey of socio-demographic, malaria burden, and communities' perception towards malaria control was conducted in 200 households selected at random from 12 villages using standard questionnaire. Households were revisited after three years of project implementation for impact assessment. Compiled malaria case data was obtained from district health bureau for the three years period of the study while adult mosquito collection was conducted during each year using CDC light traps. Monthly larval mosquito collections were made each year using standard dipping method. Community education and mobilization (CEM) was made through different community-based structures. RESULTS: The proportion of respondents who sought treatment in health facilities showed a significant increase from 76% in 2015 to 90% in 2018(P < 0.001). An average of 6.3 working and 2.3 school days were lost per year in a household due to parents and children falling sick with malaria. Malaria costs in a household in Botor-Tolay averaged 13.3 and 4.5 USD per episode for medical treatment and transportation respectively. Significantly fewer adult mosquitoes were collected in 2018 (0.37/house/trap-night) as compared to 2015 (0.73/house/trap-night) (P < .001). Malaria cases significantly declined in 2018 (262) when compared to the record in 2015 (1162) (P < 0.001). Despite improved human behavioral changes towards mosquito and malaria control, there were many setbacks too. These include reluctance to seek treatment in a timely manner, low user compliance of LLINs and low net repairing habit. CONCLUSION: The coordinated implementation of community-based education, environmental management, larviciding together with main core vector control interventions in Botor-Tolay district in Southwestern Ethiopia have contributed to significant decline in malaria cases reported from health facilities. However, commitment to seeking treatment by people with clinical symptoms of malaria and to repair of damaged mosquito nets remained low.


Assuntos
Participação da Comunidade , Malária/prevenção & controle , Controle de Mosquitos/métodos , Mosquitos Vetores , Adulto , Etiópia/epidemiologia , Características da Família , Feminino , Educação em Saúde , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Mosquiteiros Tratados com Inseticida/estatística & dados numéricos , Malária/epidemiologia , Masculino , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Avaliação de Programas e Projetos de Saúde , Inquéritos e Questionários
13.
Parasit Vectors ; 12(1): 474, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31610804

RESUMO

BACKGROUND: The global spread of mosquito-borne diseases (MBD) has presented increasing challenges to public health. The transmission of MBD is mainly attributable to the biting behaviors of female mosquitoes. However, the ecological pattern of hourly host-seeking behavior in Aedes albopictus and its association with climatic variables are still not well understood, especially for a precise requirement for establishing an effective risk prediction system of MBD transmission. METHODS: Mosquito samples and data on mosquito hourly density and site-specific climatic variables, including temperature, relative humidity, illuminance and wind speed, were collected simultaneously in urban outdoor environments in Guangzhou during 2016-2018. Kernel regression models were used to assess the temporal patterns of hourly host-seeking behavior in mosquito populations, and negative binomial regression models in the Bayesian framework were used to investigate the associations of host-seeking behavior with climatic variables. RESULTS: Aedes albopictus was abundant, constituting 82% (5569/6790) of the total collected mosquitoes. Host-seeking behavior in Ae. albopictus varied across time and was significantly influenced by climatic variables. The predicted hourly mosquito densities showed non-linear relationships with temperature and illuminance, whereas density increased with relative humidity but generally decreased with wind speed. The range of temperature estimates for female biting was 16.4-37.1 °C, peaking at 26.5 °C (95% credible interval: 25.3-28.1). During the favorable periods, biting behavior of female Ae. albopictus was estimated to occur frequently all day long, presenting a bimodal distribution with peaks within 2-3 h around both dawn and dusk (05:00-08:00 h and 16:00-19:00 h). Moreover, a short-term association in hourly density between the females and males was found. CONCLUSIONS: Our field-based modeling study reveals that hourly host-seeking behavior of Ae. albopictus exhibits a complex pattern, with hourly variation constrained significantly by climatic variables. These findings lay a foundation for improving MBD risk assessments as well as practical strategies for vector control. For instances of all-day-long frequent female biting during the favorable periods in Guangzhou, effective integrated mosquito control measures must be taken throughout the day and night.


Assuntos
Aedes/fisiologia , Clima , Comportamento de Busca por Hospedeiro/fisiologia , Mosquitos Vetores/fisiologia , /prevenção & controle , Aedes/genética , Animais , Teorema de Bayes , Distribuição Binomial , China/epidemiologia , Complexo IV da Cadeia de Transporte de Elétrons/genética , Feminino , Humanos , Umidade , Mordeduras e Picadas de Insetos/epidemiologia , Luz , Masculino , Mitocôndrias/enzimologia , Controle de Mosquitos , Mosquitos Vetores/genética , Reação em Cadeia da Polimerase , Densidade Demográfica , Chuva , Análise de Regressão , Estações do Ano , Temperatura Ambiente , Fatores de Tempo , Vento
14.
Parasit Vectors ; 12(1): 477, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31610813

RESUMO

BACKGROUND: The Asian tiger mosquito, Aedes (Stegomyia) albopictus (Skuse) is an important worldwide invasive species and can be a locally important vector of chikungunya, dengue and, potentially, Zika. This species is native to Southeast Asia where populations thrive in both temperate and tropical climates. A better understanding of the population structure of Ae. albopictus in Lao PDR is very important in order to support the implementation of strategies for diseases prevention and vector control. In the present study, we investigated the genetic variability of Ae. albopictus across a north-south transect in Lao PDR. METHODS: We used variability in a 1337-bp fragment of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1), to assess the population structure of Ae. albopictus in Lao PDR. For context, we also examined variability at the same genetic locus in samples of Ae. albopictus from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA. RESULTS: We observed very high levels of genetic polymorphism with 46 novel haplotypes in Ae. albopictus from 9 localities in Lao PDR and Thailand populations. Significant differences were observed between the Luangnamtha population and other locations in Lao PDR. However, we found no evidence of isolation by distance. There was overall little genetic structure indicating ongoing and frequent gene flow among populations or a recent population expansion. Indeed, the neutrality test supported population expansion in Laotian Ae. albopictus and mismatch distribution analyses showed a lack of low frequency alleles, a pattern often seen in bottlenecked populations. When samples from Lao PDR were analyzed together with samples from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA, phylogenetic network and Bayesian cluster analysis showed that most populations from tropical/subtropical regions are more genetically related to each other, than populations from temperate regions. Similarly, most populations from temperate regions are more genetically related to each other, than those from tropical/subtropical regions. CONCLUSIONS: Aedes albopictus in Lao PDR are genetically related to populations from tropical/subtropical regions (i.e. Thailand, Singapore, and California and Texas in the USA). The extensive gene flow among locations in Lao PDR indicates that local control is undermined by repeated introductions from untreated sites.


Assuntos
Aedes/fisiologia , Mosquitos Vetores/fisiologia , Aedes/classificação , Aedes/genética , Aedes/virologia , Algoritmos , Animais , Ásia Sudeste , Teorema de Bayes , Análise por Conglomerados , DNA/química , DNA/isolamento & purificação , Complexo IV da Cadeia de Transporte de Elétrons/genética , Extremo Oriente , Feminino , Variação Genética , Genética Populacional , Haplótipos , Itália , Laos , Mitocôndrias/enzimologia , Controle de Mosquitos , Mosquitos Vetores/classificação , Mosquitos Vetores/genética , Mosquitos Vetores/virologia , Filogenia , Análise de Sequência de DNA , Clima Tropical , Estados Unidos
15.
Malar J ; 18(1): 311, 2019 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-31521176

RESUMO

BACKGROUND: Malaria remains one of the most important causes of morbidity and death in sub-Saharan Africa. Along with early diagnosis and treatment of malaria cases and intermittent preventive treatment in pregnancy (IPTp), vector control is an important tool in the reduction of new cases. Alongside the use of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), targeting the vector larvae with biological larvicides, such as Bacillus thuringiensis israelensis (Bti) is gaining importance as a means of reducing the number of mosquito larvae before they emerge to their adult stage. This study presents data corroborating the entomological impact of such an intervention in a rural African environment. METHODS: The study extended over 2 years and researched the impact of biological larviciding with Bti on malaria mosquitoes that were caught indoors and outdoors of houses using light traps. The achieved reductions in female Anopheles mosquitoes were calculated for two different larviciding choices using a regression model. RESULTS: In villages that received selective treatment of the most productive breeding sites, the number of female Anopheles spp. dropped by 61% (95% CI 54-66%) compared to the pre-intervention period. In villages in which all breeding sites were treated, the number of female Anopheles spp. was reduced by 70% (95% CI 64-74%) compared to the pre-intervention period. CONCLUSION: It was shown that malaria vector abundance can be dramatically reduced through larviciding of breeding habitats and that, in many geographical settings, they are a viable addition to current malaria control measures.


Assuntos
Anopheles , Bacillus thuringiensis/química , Inseticidas/uso terapêutico , Controle de Mosquitos/métodos , Mosquitos Vetores , Controle Biológico de Vetores/métodos , Animais , Anopheles/crescimento & desenvolvimento , Burkina Faso , Feminino , Larva/crescimento & desenvolvimento , Mosquitos Vetores/crescimento & desenvolvimento
16.
Acta Trop ; 200: 105171, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31521623

RESUMO

The ability of Aedes albopictus Skuse to transmit several pathogens to humans makes it a very important mosquito with public health significance. Ecofriendly products as alternatives to synthetic chemicals for the control of mosquito vectors are needed. Therefore, the larvicidal and repellent effects of two nontoxic chemicals, butyl anthranilate (BA) and ethyl anthranilate (EA), at different concentrations were compared in A. albopictus. The repellency persistence of BA and three commercial mosquito repellent products (Liushen repellent spray, DKB Korean, Raid repellent spray) against A. albopictus was compared. The results showed that 0.1% concentrations of BA and EA solutions were highly toxic to A. albopictus larvae, and the mortality rate was >90% after 4 h of treatment. We found that BA was more repellent than EA, and at 0.1% BA and 1% EA, and the repellency rates were 53.62% and 38.47%, respectively. Overall, 5% BA presented a significantly longer repellency time than the three commercial repellent products against female A. albopictus. These results indicate that BA has significant larvicidal and repellent effects and can be exploited further for the development of ecofriendly alternatives to existing toxic chemicals currently used for mosquito control.


Assuntos
Aedes/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Larva/efeitos dos fármacos , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , ortoaminobenzoatos/farmacologia , Animais , Feminino , Humanos
17.
BMC Infect Dis ; 19(1): 800, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31510931

RESUMO

BACKGROUND: Larviciding is an effective supplementary tool for malaria vector control, but the identification and accessibility of aquatic habitats impedes application. Dissemination of the insect growth regulator, pyriproxyfen (PPF), by gravid Anopheles might constitute a novel application strategy. This study aimed to explore the feasibility of using an attractive bait-station to contaminate gravid Anopheles gambiae sensu stricto with PPF and subsequently transfer PPF to larval habitats. METHODS: A bait-station was developed comprising of an artificial pond containing water treated with 20 ppm cedrol, an oviposition attractant, and a netting-cover treated with PPF. Three identical semi-field cages were used to assess the potential of gravid Anopheles to transfer PPF from the bait-station to ponds. Gravid females were released in two semi-field cages, one with PPF on its bait-station (test) and one without PPF (control). No mosquitoes were released in the third cage with a PPF-treated station (control). Transfer of PPF to open ponds was assessed by monitoring emergence of late instar insectary-reared larvae introduced into the ponds. The amount of PPF carried by a mosquito and transferred to water was quantified using liquid chromatography-mass spectrometry. RESULTS: In the controls, 86% (95% CI 81-89%) of larvae introduced into open ponds developed into adults, indicating that wind did not distribute PPF in absence of mosquitoes. Emergence inhibition was observed in the test cage but was dependent on the distance between pond and bait-station. Only 25% (95% CI 22-29%) of larvae emerged as adults from ponds 4 m from the bait-station, but 92% (95% CI 89-94%) emerged from ponds 10 m away. Each mosquito was contaminated on average with 112 µg (95% CI 93-123 µg) PPF resulting in the transfer of 230 ng/L (95% CI 180-290 ng/L) PPF to 100 ml volumes of water. CONCLUSIONS: The bait-stations successfully attracted gravid females which were subsequently dusted with effective levels of PPF. However, in this study design, attraction and dissemination was limited to short distances. To make this approach feasible for malaria vector control, stronger attractants that lure gravid females from longer distances, in landscapes with many water bodies, and better PPF delivery systems are needed.


Assuntos
Anopheles/efeitos dos fármacos , Inseticidas/toxicidade , Controle de Mosquitos/métodos , Piridinas/toxicidade , Animais , Anopheles/crescimento & desenvolvimento , Anopheles/fisiologia , Feminino , Larva/efeitos dos fármacos , Oviposição , Tanques , Terpenos/farmacologia
18.
Lancet ; 394(10203): 990-991, 2019 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-31511197
19.
Cell Host Microbe ; 26(3): 309-313, 2019 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-31513769

RESUMO

The inexorable emergence of mosquito-borne arboviruses and the failure of traditional vector control methods to prevent their transmission have triggered the development of alternative entomological interventions to render mosquito populations incapable of carrying arboviruses. Here, we use a theoretical framework to argue that decreasing mosquito tolerance to arbovirus infection could be a more evolutionarily sustainable disease control strategy than increasing mosquito resistance. Increasing resistance is predicted to select for mutant arboviruses escaping resistance, whereas reducing tolerance should lead to the death of infected vectors and thus select for mosquito-attenuated arbovirus variants that are less transmissible.


Assuntos
Infecções por Arbovirus/prevenção & controle , Arbovirus/fisiologia , Culicidae/virologia , Controle de Mosquitos/métodos , Mosquitos Vetores/virologia , Animais , Infecções por Arbovirus/transmissão , Evolução Biológica , Simulação por Computador , Interações Hospedeiro-Patógeno/fisiologia , Humanos , Modelos Biológicos
20.
Malar J ; 18(1): 322, 2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31547828

RESUMO

BACKGROUND: This paper outlines Zimbabwe's potential readiness in harnessing integrated vector management (IVM) strategy for enhanced control of vector-borne diseases. The objective is to provide guidance for the country in the implementation of the national IVM strategy in order to make improvements required in thematic areas of need. The paper also assesses the existing opportunities and gaps to promote and adopt the approach as a national policy. MAIN TEXT: Despite recent gains in combating vector-borne diseases, especially malaria, management of vector control programmes still remains insecticide-based and vertical in nature. Therefore, concerns have been raised on whether the current long-standing conventional vector control strategy still remains with sufficient action to continue to break the transmission cycle to the levels of elimination. This is so, given the continuous dwindling resources for vector control, changes in vector behaviour, the emergence of resistance to medicines and insecticides, climate change, environmental degradation, as well as diversity in ecology, breeding habitats, and community habits. Cognizant of all that, elements of a surveillance-driven IVM approach are rapidly needed to move vector control interventions a step further. These include advocacy, policy formulation, capacity building, public and private partnerships, community engagement, and increasingly basing decisions on local evidence. Understanding the existing opportunities and gaps, and the recognition that some elements of IVM are already imbedded in the current health programmes is important to encourage stakeholders to promptly support its implementation. Leveraging on the existing opportunities, combined with sufficient advocacy, IVM could easily be accepted by the Zimbabwe government as part of a wider integrated disease management strategy. The strategy could represent an excellent breakthrough to establish much needed intra and inter-sectoral dialogue, and coordination for improved vector-borne disease prevention. CONCLUSIONS: After synthesis of the opportunities and challenges clearly presented, it was concluded that it is imperative for Zimbabwe to adopt and implement IVM strategy that is informed by work already done, while addressing the bottlenecks. The significance of refocusing for improved disease prevention that has the potential to accomplish elimination of not only malaria but all vector borne diseases much earlier than anticipated under the existing vector control system is underscored.


Assuntos
Anopheles , Controle de Doenças Transmissíveis/legislação & jurisprudência , Política de Saúde/legislação & jurisprudência , Malária/prevenção & controle , Controle de Mosquitos/métodos , Mosquitos Vetores , Animais , Zimbábue
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