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Mem. Inst. Oswaldo Cruz ; 115: e200070, 2020. tab, graf
Article in English | SES-SP, LILACS, SES-SP | ID: biblio-1135278


BACKGROUND Nyssorhynchus deaneorum is a potential malaria vector because it has been shown to be competent to transmit Plasmodium vivax and Plasmodium falciparum, and because it exhibits antropophilic and endophilic behaviors in some regions of the Amazon. This profile makes Ny. deaneorum a useful mosquito for experiments that model Plasmodium-vector interactions in the Amazon. OBJECTIVE Herein we describe how a free-mating colony of Ny. deaneorum has been established using an automated light stimulation system. METHODS Mosquitoes were captured in São Francisco do Guaporé, Rondônia. The F1 generation was reared until adult emergence at which point copulation was induced using an automatic copulation induction system (ACIS). FINDINGS After four generations, natural mating and oviposition began to occur without light stimulation. The number of pupae and adult mosquitoes increased from the F5 to F10 generations. The new Ny. deaneorum colony exhibited susceptibility to P. vivax. MAIN CONCLUSIONS Automated light stimulation is an effective method for establishing an Ny. deaneorum colony under laboratory conditions as it produces enough adults to create a stenogamic colony. The establishment of a stable, P. vivax-susceptible colony of Ny. deaneorum makes it possible to model parasite-vector interactions and to test novel drug therapies that target parasite development in mosquitoes.

Animals , Female , Oviposition , Copulation/physiology , Mosquito Vectors/parasitology , Insect Vectors/growth & development , Malaria , Anopheles/parasitology , Plasmodium falciparum , Plasmodium vivax , Brazil , Insect Vectors/physiology , Anopheles/physiology
Rev. Soc. Bras. Med. Trop ; 52: e20190159, 2019. graf
Article in English | LILACS | ID: biblio-1041542


Abstract INTRODUCTION: The lack of highly-productive Nyssorhynchus darlingi laboratory colonies limits some studies. We report the first well-established laboratory colony of Ny. darlingi in Brazil. METHODS: Mosquitoes were collected from Porto Velho and were reared at the Laboratory of Fiocruz/RO. After induced mating by light stimulation in the F1 to F6, the subsequent generations were free mating. Larvae were reared in distilled water and fed daily until pupation. RESULTS: In 11 generations, the colony produced a high number of pupae after the F5 generation. CONCLUSIONS: These results demonstrate the potential for permanently establishing Ny. darlingi colonies for research purposes in Brazil.

Animals , Mosquito Vectors/growth & development , Anopheles/growth & development , Oviposition , Reproduction , Brazil , Mosquito Vectors/physiology , Malaria , Anopheles/physiology
Mem. Inst. Oswaldo Cruz ; 113(2): 87-95, Feb. 2018. tab, graf
Article in English | LILACS | ID: biblio-894897


BACKGROUND Studies on malaria vectors in the Pantanal biome, Central Brazil, were conducted more than half a century ago. OBJECTIVES To update anopheline records and assess receptivity and vulnerability to malaria transmission. METHODS Five-day anopheline collections were conducted bimonthly in Salobra, Mato Grosso do Sul state, for one year. Indoors, mosquitoes were collected from their resting places, while in open fields, they were captured using protected human-baited and horse-baited traps near the house and at the Miranda River margin, respectively. Hourly biting activity outdoors was also assessed. Secondary data were collected on the arrival of tourists, economic projects, and malaria cases. FINDINGS A total of 24,894 anophelines belonging to 13 species were caught. The main Brazilian malaria vector Anopheles darlingi was the predominant species, followed by An. triannulatus s.l. Hourly variation in anopheline biting showed three main peaks occurring at sunset, around midnight, and at sunrise, the first and last being the most prominent. The highest density of all species was recorded near the river margin and during the transition period between the rainy and early dry seasons. This coincides with the time of main influx of outsider workers and tourists, whose activities mostly occur in the open fields and frequently start before sunrise and last until sunset. Some of these individuals originate from neighbouring malaria-endemic countries and states, and are likely responsible for the recorded imported and introduced malaria cases. MAIN CONCLUSION Pantanal is a malaria-prone area in Brazil. Surveillance and anopheline control measures must be applied to avoid malaria re-emergence in the region.

Animals , Oviposition , Malaria/transmission , Anopheles/classification , Anopheles/physiology , Mosquito Vectors , Anopheles/parasitology
Mem. Inst. Oswaldo Cruz ; 111(9): 561-569, Sept. 2016. tab, graf
Article in English | LILACS | ID: lil-794724


In French Guiana, malaria vector control and prevention relies on indoor residual spraying and distribution of long lasting insecticidal nets. These measures are based on solid epidemiological evidence but reveal a poor understanding of the vector. The current study investigated the behaviour of both vectors and humans in relation to the ongoing prevention strategies. In 2012 and 2013, Anopheles mosquitoes were sampled outdoors at different seasons and in various time slots. The collected mosquitoes were identified and screened for Plasmodium infection. Data on human behaviour and malaria episodes were obtained from an interview. A total of 3,135 Anopheles mosquitoes were collected, of which Anopheles darlingi was the predominant species (96.2%). For the December 2012-February 2013 period, the Plasmodium vivax infection rate for An. darlingi was 7.8%, and the entomological inoculation rate was 35.7 infective bites per person per three-month span. In spite of high bednet usage (95.7%) in 2012 and 2013, 52.2% and 37.0% of the participants, respectively, had at least one malaria episode. An. darlingi displayed heterogeneous biting behaviour that peaked between 20:30 and 22:30; however, 27.6% of the inhabitants were not yet protected by bednets by 21:30. The use of additional individual and collective protective measures is required to limit exposure to infective mosquito bites and reduce vector densities.

Humans , Animals , Female , Anopheles/physiology , Insect Bites and Stings , Insect Vectors/physiology , Anopheles/classification , Anopheles/parasitology , Forests , French Guiana , Insect Vectors/classification , Insect Vectors/parasitology , Malaria, Falciparum/transmission , Malaria, Vivax/transmission , Population Density , Seasons , Species Specificity
Mem. Inst. Oswaldo Cruz ; 110(6): 760-770, Sept. 2015. tab, graf
Article in English | LILACS | ID: lil-763087


Here we present the first in a series of articles about the ecology of immature stages of anophelines in the Brazilian Yanomami area. We propose a new larval habitat classification and a new larval sampling methodology. We also report some preliminary results illustrating the applicability of the methodology based on data collected in the Brazilian Amazon rainforest in a longitudinal study of two remote Yanomami communities, Parafuri and Toototobi. In these areas, we mapped and classified 112 natural breeding habitats located in low-order river systems based on their association with river flood pulses, seasonality and exposure to sun. Our classification rendered seven types of larval habitats: lakes associated with the river, which are subdivided into oxbow lakes and nonoxbow lakes, flooded areas associated with the river, flooded areas not associated with the river, rainfall pools, small forest streams, medium forest streams and rivers. The methodology for larval sampling was based on the accurate quantification of the effective breeding area, taking into account the area of the perimeter and subtypes of microenvironments present per larval habitat type using a laser range finder and a small portable inflatable boat. The new classification and new sampling methodology proposed herein may be useful in vector control programs.

Animals , Humans , Anopheles/physiology , Disease Vectors , Entomology/methods , Indians, South American , Mosquito Control/trends , Rainforest , Brazil , Ecosystem , Lakes , Larva , Longitudinal Studies , Reproduction , Rivers , Seasons , Sunlight
Mem. Inst. Oswaldo Cruz ; 109(7): 905-911, 11/2014. tab, graf
Article in English | LILACS | ID: lil-728805


The physical integrity of bednets is a concern of national malaria control programs, as it is a key factor in determining the rate of replacement of bednets. It is largely assumed that increased numbers of holes will result in a loss of protection of sleepers from potentially infective bites. Experimental hut studies are valuable in understanding mosquito behaviour indoors, particularly as it relates to blood feeding and mortality. This review summarises findings from experimental hut studies, focusing on two issues: (i) the effect of different numbers or sizes of holes in bednets and (ii) feeding behaviour and mortality with holed nets as compared with unholed nets. As might be expected, increasing numbers and area of holes resulted in increased blood feeding by mosquitoes on sleepers. However, the presence of holes did not generally have a large effect on the mortality of mosquitoes. Successfully entering a holed mosquito net does not necessarily mean that mosquitoes spend less time in contact with the net, which could explain the lack in differences in mortality. Further behavioural studies are necessary to understand mosquito behaviour around nets and the importance of holed nets on malaria transmission.

Animals , Anopheles/physiology , Behavior, Animal/physiology , Culex/physiology , Mosquito Nets , Malaria/prevention & control , Culicidae/physiology , Feeding Behavior/physiology , Insecticides , Insect Vectors/physiology , Mosquito Control/methods , Nitriles , Permethrin , Pyrethrins
Rev. Inst. Med. Trop. Säo Paulo ; 56(5): 403-409, Sep-Oct/2014. tab, graf
Article in English | SES-SP, LILACS, SES-SP | ID: lil-722331


Anopheles (Kerteszia) cruzii has been implicated as the primary vector of human and simian malarias out of the Brazilian Amazon and specifically in the Atlantic Forest regions. The presence of asymptomatic human cases, parasite-positive wild monkeys and the similarity between the parasites infecting them support the discussion whether these infections can be considered as a zoonosis. Although many aspects of the biology of An. cruzii have already been addressed, studies conducted during outbreaks of malaria transmission, aiming at the analysis of blood feeding and infectivity, are missing in the Atlantic Forest. This study was conducted in the location of Palestina, Juquitiba, where annually the majority of autochthonous human cases are notified in the Atlantic Forest of the state of São Paulo. Peridomiciliary sites were selected for collection of mosquitoes in a perimeter of up to 100 m around the residences of human malaria cases. The mosquitoes were analyzed with the purpose of molecular identification of blood-meal sources and to examine the prevalence of Plasmodium. A total of 13,441 females of An. (Ker.) cruzii were collected. The minimum infection rate was calculated at 0.03% and 0.01%, respectively, for P. vivax and P. malariae and only human blood was detected in the blood-fed mosquitoes analyzed. This data reinforce the hypothesis that asymptomatic human carriers are the main source of anopheline infection in the peridomiciliary area, making the probability of zoonotic transmission less likely to happen.

Anopheles (Kerteszia) cruzii é o vetor primário das malárias humana e simiana fora da Amazônia Brasileira e especificamente nas regiões de Mata Atlântica. A presença de casos humanos assintomáticos, macacos silvestres positivos para Plasmodium e a similaridade entre os parasitas que os infectam suportam a discussão se essas infecções podem ser consideradas como zoonoses. Embora muitos aspectos da biologia de An. cruzii já tenham sido abordados, estudos conduzidos durante surtos de transmissão de malária, visando a análise de repasto sanguíneo e infectividade, são ausentes na Mata Atlântica. Este estudo foi conduzido na localidade de Palestina, Juquitiba, Mata Atlântica do Estado de São Paulo, onde anualmente a maioria dos casos humanos autóctones é notificada. Locais em peridomicílio foram selecionados para coleta de mosquitos em um perímetro de até 100 m em torno das residências de casos humanos de malária e da floresta circundante. Os mosquitos foram analisados com o objetivo de identificação molecular das fontes de repasto sanguíneo e para examinar a prevalência de Plasmodium. Um total de 13.441 fêmeas de An. (Ker.) cruzii foi coletado. A taxa de infecção mínima foi calculada a 0,03% e 0,01%, respectivamente, para P. vivax e P. malariae e somente sangue humano foi detectado nos mosquitos analisados que se alimentaram com sangue. Nossos dados reforçam a hipótese de que os portadores humanos assintomáticos são a principal fonte de infecção para os anofelinos na área do peridomicílio, tornando a transmissão zoonótica improvável.

Animals , Female , Humans , Anopheles/physiology , Asymptomatic Infections , Feeding Behavior/physiology , Insect Vectors/physiology , Malaria/transmission , Anopheles/classification , Blood , Brazil , Insect Vectors/classification , Population Density , Seasons , Trees
Mem. Inst. Oswaldo Cruz ; 108(8): 1057-1064, 6/dez. 2013. tab, graf
Article in English | LILACS | ID: lil-697145


On the southwest Pacific Coast of Colombia, a field study was initiated to determine the human-vector association between Anopheles (Kerteszia) neivai and fishermen, including their nearby houses. Mosquitoes were collected over 24-h periods from mangrove swamps, marshlands and fishing vessels in three locations, as well as in and around the houses of fishermen. A total of 6,382 mosquitoes were collected. An. neivai was most abundant in mangroves and fishing canoes (90.8%), while Anopheles albimanus was found indoors (82%) and outdoors (73%). One An. neivai and one An. albimanus collected during fishing activities in canoes were positive for Plasmodium vivax , whereas one female An. neivai collected in a mangrove was positive for P. vivax . In the mangroves and fishing canoes, An. neivai demonstrated biting activity throughout the day, peaking between 06:00 pm-07:00 pm and there were two minor peaks at dusk and dawn. These peaks coincided with fishing activities in the marshlands and mangroves, a situation that places the fishermen at risk of contracting malaria when they are performing their daily activities. It is recommended that protective measures be implemented to reduce the risk that fishermen will contract malaria.

Animals , Female , Humans , Anopheles/physiology , Bites and Stings/epidemiology , Fisheries , Feeding Behavior/physiology , Insect Vectors/physiology , Anopheles/classification , Anopheles/parasitology , Colombia/epidemiology , Insect Vectors/classification , Insect Vectors/parasitology , Malaria/epidemiology , Malaria/transmission , Population Density , Plasmodium/isolation & purification
Biomédica (Bogotá) ; 33(2): 241-250, abr.-jun. 2013. graf
Article in Spanish | LILACS | ID: lil-689561


Introducción. Anopheles darlingi es el principal vector de la malaria, o paludismo, en el neotrópico. Esta especie es reconocida por presentar un comportamiento antropofílico y variabilidad en sus hábitos de picadura a lo largo de su rango de distribución. Objetivo. Caracterizar el comportamiento de picadura de An. darlingi y establecer su relación con la transmisión de la malaria en Villavicencio. Materiales y métodos. Entre 2008 y 2009 se llevaron a cabo un estudio de tipo transversal y uno longitudinal, en cinco localidades de Villavicencio con transmisión de malaria. Estos incluyeron recolección de ejemplares inmaduros y de adultos en las viviendas. Se utilizó la prueba ELISA para la detección de infección con Plasmodium spp. Resultados. Se recolectaron 2.772 mosquitos. Anopheles darlingi fue la especie predominante en las capturas con atrayente humano. Los criaderos identificados para esta especie fueron pantanos, caños, lagunas y estanques piscícolas. Anopheles darlingi estuvo presente durante todo el año, con densidades mensuales promedio entre 2,2 y 55,5 mosquitos por persona por noche. Presentó actividad hematofágica durante toda la noche en el intradomicilio y en el peridomicilio. De las 18:00 a las 22:00, se registraron entre el 47 % y el 81 % de los mosquitos capturados en 12 horas de observación. Se encontró una tasa de infección con Plasmodium falciparum de 0,05 % y se estimó una tasa entomológica de inoculación de 2,9 picaduras infecciosas por persona al año. Conclusión. Anopheles darlingi se encontró infectado con P. falciparum, estuvo presente durante todo el año y exhibió características en su comportamiento de picadura que favorecen el contacto entre humano y vector, lo cual es un riesgo permanente para la transmisión de la malaria en Villavicencio.

Introduction: Anopheles darlingi is the main malaria vector in the neotropics. This species is recognized by its anthropophilic behavior and its high variability in biting activity throughout its distribution range. Objective: To characterize the biting behavior of An. darlingi and to establish its association with malaria transmission in Villavicencio. Materials and methods: Between 2008 and 2009, a cross sectional and a longitudinal entomological study were carried out in 5 localities with malaria transmission in Villavicencio. Mosquito collections included breeding sites search and human landing catches in houses. Collected mosquitoes were analyzed for Plasmodium using the ELISA standard protocol. Results: A total of 2,772 mosquitoes were collected in the study. Anopheles darlingi was the most abundant anopheline species. The most common breeding sites for this species were marshes, streams, lakes and fish ponds. Anopheles darlingi was found at all times during the year with monthly average human biting rates between 2.2 y 55.5 mosquitos/person/night. This species was collected throughout the night, indoors and outdoors, and 47 to 81% of An. darling captured during twelve hours of observation (18:00 to 06:00) were collected between18:00 and 22:00. Anopheles darlingi was found positive for P. falciparum with a 0.05% rate and the entomological inoculation rate was estimated at 2.9 infective bites/person per year. Conclusion: Anopheles darlingi was infected with P. falciparum, it was found all year long and it exhibited characteristics in biting behavior that favor human-vector contact, being a permanent risk for malaria transmission in Villavicencio.

Animals , Humans , Anopheles/physiology , Insect Bites and Stings/complications , Malaria/transmission , Cross-Sectional Studies , Colombia/epidemiology , Feeding Behavior , Insect Bites and Stings/epidemiology , Longitudinal Studies , Malaria/epidemiology
Mem. Inst. Oswaldo Cruz ; 108(2): 220-228, abr. 2013. tab, graf
Article in English | LILACS | ID: lil-670400


To explore the effects of deforestation and resulting differences in vegetation and land cover on entomological parameters, such as anopheline species composition, abundance, biting rate, parity and entomological inoculation rate (EIR), three villages were selected in the Lower Caura River Basin, state of Bolívar, Venezuela. All-night mosquito collections were conducted between March 2008-January 2009 using CDC light traps and Mosquito Magnet(r) Liberty Plus. Human landing catches were performed between 06:00 pm-10:00 pm, when anophelines were most active. Four types of vegetation were identified. The Annual Parasite Index was not correlated with the type of vegetation. The least abundantly forested village had the highest anopheline abundance, biting rate and species diversity. Anopheles darlingi and Anopheles nuneztovari were the most abundant species and were collected in all three villages. Both species showed unique biting cycles. The more abundantly forested village of El Palmar reported the highest EIR. The results confirmed previous observations that the impacts of deforestation and resulting changes in vegetation cover on malaria transmission are complex and vary locally.

Animals , Female , Humans , Male , Anopheles/classification , Biodiversity , Feeding Behavior/physiology , Insect Vectors/classification , Malaria/transmission , Anopheles/physiology , Insect Bites and Stings , Insect Vectors/physiology , Longitudinal Studies , Malaria/epidemiology , Population Density , Risk Factors , Rivers , Seasons , Venezuela/epidemiology
Mem. Inst. Oswaldo Cruz ; 108(supl.1): 48-58, 2013. graf
Article in English | LILACS | ID: lil-697831


Organisms from bacteria to humans have evolved under predictable daily environmental cycles owing to the Earth’s rotation. This strong selection pressure has generated endogenous circadian clocks that regulate many aspects of behaviour, physiology and metabolism, anticipating and synchronising internal time-keeping to changes in the cyclical environment. In haematophagous insect vectors the circadian clock coordinates feeding activity, which is important for the dynamics of pathogen transmission. We have recently witnessed a substantial advance in molecular studies of circadian clocks in insect vector species that has consolidated behavioural data collected over many years, which provided insights into the regulation of the clock in the wild. Next generation sequencing technologies will facilitate the study of vector genomes/transcriptomes both among and within species and illuminate some of the species-specific patterns of adaptive circadian phenotypes that are observed in the field and in the laboratory. In this review we will explore these recent findings and attempt to identify potential areas for further investigation.

Animals , Circadian Rhythm/genetics , Culicidae/genetics , Drosophila melanogaster/genetics , Insect Vectors/genetics , Period Circadian Proteins/genetics , Anopheles/physiology , Psychodidae/physiology
Mem. Inst. Oswaldo Cruz ; 106(supl.1): 239-245, Aug. 2011. ilus, tab
Article in English | LILACS | ID: lil-597266


Every year, autochthonous cases of Plasmodium vivax malaria occur in low-endemicity areas of Vale do Ribeira in the south-eastern part of the Atlantic Forest, state of São Paulo, where Anopheles cruzii and Anopheles bellator are considered the primary vectors. However, other species in the subgenus Nyssorhynchus of Anopheles (e.g., Anopheles marajoara) are abundant and may participate in the dynamics of malarial transmission in that region. The objectives of the present study were to assess the spatial distribution of An. cruzii, An. bellator and An. marajoara and to associate the presence of these species with malaria cases in the municipalities of the Vale do Ribeira. Potential habitat suitability modelling was applied to determine both the spatial distribution of An. cruzii, An. bellator and An. marajoara and to establish the density of each species. Poisson regression was utilized to associate malaria cases with estimated vector densities. As a result, An. cruzii was correlated with the forested slopes of the Serra do Mar, An. bellator with the coastal plain and An. marajoara with the deforested areas. Moreover, both An. marajoara and An. cruzii were positively associated with malaria cases. Considering that An. marajoara was demonstrated to be a primary vector of human Plasmodium in the rural areas of the state of Amapá, more attention should be given to the species in the deforested areas of the Atlantic Forest, where it might be a secondary vector.

Animals , Humans , Anopheles/physiology , Ecosystem , Insect Vectors/physiology , Plasmodium , Trees , Anopheles , Anopheles , Brazil , Insect Vectors , Insect Vectors , Malaria/transmission , Poisson Distribution , Rural Population
Article in English | IMSEAR | ID: sea-135711


Background & objectives: Anopheles minimus has recently been reported to have re-appeared in Keonjhar district of Orissa after a period of about 45 years of launching the malaria eradication programme. An. minimus and An. fluviatilis were the incriminated major malaria vectors in the district, endemic for falciparum malaria. The information on seasonal prevalence and resting behaviour of the vectors is crucial for implementing appropriate malaria control measures. Therefore, a study was undertaken on seasonal prevalence and resting behaviour of An. minimus and An. fluviatilis in this district. Methods: Seven randomly selected villages of Keonjhar district, Orissa, were studied during August 2005 to November 2007. Daytime resting collections indoors and outdoors were made covering three seasons of the year. The Anopheles mosquitoes obtained from different habitats were identified. Collections were maintained separately according to different sites as well as heights of the walls in human dwellings. Results: Among the indoor collections, the densities of An. minimus and An. fluviatilis were higher in human dwellings than cattle sheds. An. fluviatilis was the predominant (41.5%) species followed by An. minimus (26.3%) in human dwellings. The density of both the vector species in human dwellings peaked during rainy and winter seasons followed by summer. Walls were the most preferred site by these vectors for resting and the maximum number was collected at a height of 3 to 4 ft. Interpretation & conclusions: The resting behaviour of the vector species increases their contact with the sprayed walls and therefore, a quality residual spraying of human dwellings focusing indoor walls could interrupt the malaria transmission in this area.

Animals , Anopheles/microbiology , Anopheles/physiology , Cattle , Female , Humans , India/epidemiology , Insect Vectors/microbiology , Insect Vectors/physiology , Malaria, Falciparum/epidemiology , Malaria, Falciparum/prevention & control , Malaria, Falciparum/transmission , Male , Mosquito Control/methods , Seasons
Rio de Janeiro; Fiocruz; 2011. 373 p. ilus, mapas, tab, graf.(História e saúde. Classícos e fontes).
Monography in Portuguese | LILACS | ID: lil-620605


Fred L. Soper e D. Bruce Wilson lideraram uma campanha sanitária no Nordeste brasileiro que culminou com a erradicação, em tempo recorde – apenas 35 meses –, do mais eficiente dentre os vetores da malária, o mosquito Anopheles gambiae. Considerado leitura obrigatória para os interessados em saúde pública no Brasil, o relatório final dessa campanha – que descreve detalhadamente os procedimentos e métodos de trabalho sob o ponto de vista de seus diretores – foi originalmente publicado em inglês, em 1943. Pouco depois, em 1945, o relatório ganhou uma edição em português, mas não uma tradução fiel. Ela se voltava para as atividades do Serviço de Malária do Nordeste e a questão dos doentes de malária, enquanto o original era centrado nas ações da Fundação Rockefeller e na campanha de erradicação do mosquito. Decidiu-se, então, retraduzir o original – encontrado hoje em dia somente na seção de obras raras de bibliotecas especializadas –, incorporando alguns elementos de destaque da primeira versão em português. O resultado desse esforço é este novo volume da Coleção História e Saúde; Clássicos e Fontes.

Humans , History, 20th Century , Anopheles/physiology , Anopheles/parasitology , Anopheles/pathogenicity , Insect Vectors , Malaria/prevention & control , Brazil/epidemiology
Rev. Soc. Bras. Med. Trop ; 43(5): 516-522, set.-out. 2010. ilus, tab
Article in English | SES-SP, LILACS, SES-SP | ID: lil-564286


INTRODUCTION: Study of the temporal activity of malaria vectors during the implantation of a hydroelectric power station on the River Paraná, intended to generate electrical energy. The river separates the States of São Paulo and Mato Grosso do Sul, in Brazil. The objective was to verify whether alterations occurred in the wealth and diversity indices of Anopheles, following two successive floods, extended to the temporal activity and nycthemeral rhythm followed over a five year period. METHODS: Mosquito capture was performed monthly using the Human Attraction Technique and Shannon Traps. The first, executed for 24h, provided the nycthemeral rhythm and the second, lasting 15h, permitted the tracking of Anopheles during the two floods. RESULTS: The bimodal pattern of Anopheles darlingi defined before these floods was modified throughout the environment interventions. The same effect had repercussions on the populations of An albitarsis s.l., An triannulatus and An galvaoi. Activity prior to twilight was less affected by the environment alterations. CONCLUSIONS: The dam construction provoked changes in Anopheles temporal activity patterns, permitting classification of the area as an ecologically steady and unstable situation. Differences observed in Anopheles behavior due to the capture methods revealed the influence of solo and multiple attractiveness inside the populations studied.

INTRODUÇÃO: Estudo da atividade horária de vetores da malária durante a implantação de uma represa no Rio Paraná, destinada à geração de energia elétrica. O rio separa os Estados de São Paulo e Mato Grosso do Sul, no Brasil. O objetivo foi verificar se as alterações na riqueza e diversidades de Anopheles diante de duas inundações sucessivas se estendiam à atividade horária e ritmo nictimeral numa série temporal de cinco anos. MÉTODOS: A captura de mosquito foi mensal, por meio dos métodos Técnica Atrativa Humana e Armadilha de Shannon. A primeira, executada durante 24 horas, forneceu o ritmo nictimeral e a segunda, com duração de 15 horas, para acompanhar os anofelinos durante as duas inundações. RESULTADOS: O padrão bimodal de Anopheles darlingi definido antes dessas inundações foi alterado ao longo das intervenções ambientais. O mesmo efeito repercutiu nas populações de An albitarsis s.l., An triannulatus e An galvaoi. A atividade pré-crepuscular foi a menos afetada pelas alterações ambientais. CONCLUSÕES: As barragens provocam mudanças no padrão de atividade horária dos anofelinos permitindo classificar a área em situação ecologicamente estável e instável. Diferenças observadas no comportamento dos anofelinos pelos métodos de captura mostram a influência da uni e múltipla atratividade dentro das populações estudadas.

Animals , Anopheles/physiology , Biodiversity , Circadian Rhythm/physiology , Floods , Insect Vectors/physiology , Power Plants , Anopheles/classification , Brazil , Population Density , Population Dynamics
Article in English | IMSEAR | ID: sea-135578


Background & objectives: Under the national antimalaria programme DDT was introduced in early 1950s for vector control and later hexachloro cyclohexane (HCH) followed by malathion and recently synthetic pyrethroids in 1990s to manage the insecticide resistance in Anopheles culicifacies. Subsequent replacement led to development of multiple resistances in An. culicifacies in Surat district in Gujarat State. Indoor residual spray (IRS) was completely withdrawn in southern villages in Surat in 2002. This study was undertaken in these areas to study the persistence of resistance to DDT, malathion and deltamethrin after sequential withdrawal of IRS with these insecticides at different times. Methods: Susceptibility tests on An. culicifacies were conducted using standard WHO methods and kits. Mortality, knockdown time and lethal times were calculated for An. culicifacies exposed to WHO prescribed diagnostic concentrations of different insecticide impregnated papers. Results: Persistence of DDT-resistance was observed even after 30 yr of its withdrawal from IRS. Similarly, persistence of malathion resistance was also observed after 9 yr of its withdrawal from IRS, while reversal of deltamethrin-resistance was observed very fast within 2-3 yr after its withdrawal from IRS in 2002. Interpretation & conclusion: Present data indicate that the quantum of reversion of insecticide resistance in a population is relative and depends on the genetic stability of the respective resistance genes in the mosquitoes. In the present study withdrawal of pyrethroid-IRS resulted in increased susceptibility against pyrethroids alone and was independent of existence of resistance to insecticides of other groups. This study emphasizes that appropriate rotation of different insecticides; including carbamates may prevent or delay the onset of resistance.

Animals , Anopheles/drug effects , Anopheles/genetics , Anopheles/physiology , DDT/toxicity , Genetics, Population , India , Insecticide Resistance/genetics , Insecticides/toxicity , Malathion/toxicity , Mortality , Mosquito Control/methods , Nitriles/toxicity , Pyrethrins/toxicity , Regression Analysis , Time Factors
Bol. malariol. salud ambient ; 50(1): 95-107, jul. 2010. ilus, tab
Article in Spanish | LILACS | ID: lil-630430


Se reporta por primera vez una lista de especies de anofelinos y culicinos presentes en el territorio indígena del Bajo Caura, estado Bolívar. Entre larvas y adultos se colectaron en total ocho especies de anofelinos pertenecientes a los subgéneros Anopheles Meigen, Lophopodomyia Antunes, Stethomyia Theobald, Nyssorhynchus Blanchard del género Anopheles Meigen y Chagasia bathana Dyar y 10 géneros de culicinos entre los cuales se identificaron siete especies. Se identificaron y caracterizaron los criaderos con base a la hidrología en arroyo, caño, manantial, laguna, pantano y charco. En colectas de estadíos inmaduros la especie más abundante fue Anopheles triannulatus (Neiva & Pinto), mientras que en colectas de adultos con cebos humanos y trampas CDC la especie más abundante fue el vector de malaria An. darlingi Root. Las trampas de luz ultravioleta resultaron ineficientes para capturar anofelinos y culicinos. Se reporta por primera vez para el estado Bolívar los géneros Coquillettidia Dyar y Johnbelkinia Zavortink, así como las especies Aedes (Ochlerotatus) fulvus (Wiedemann) y Ae. (Och.) serratus (Theobald)

This is the first report of anophelines and culicines species in the indigenous territory of the Lower Caura River, Bolívar State. A total of 8 species of anophelines belonging to the subgenus Anopheles Meigen, Lophopodomyia Antunes, Stethomyia Theobald, Nyssorhynchus Blanchard of the genus Anopheles Meigen and Chagasia bathana Dyar and 10 genera of culicines were collected and 7 species identified. Larval habitats were identified and characterized based on the hidrology in stream, small river, spring, lagoon, swamp and pool. Culicines were also collected in artificial and natural containers. The most abundant species in collections of inmature stages was Anopheles triannulatus (Neiva & Pinto), while in adult collections on human landing catches and CDC light traps the most abundant species was the malaria vector An. darling Root. Ultra violet up draft light traps were inefficient to collect anophelines and culicines. It is reported for the first time the presence in Bolívar State of the genus Coquillettidia Dyar and Johnbelkinia Zavortink, and the species Aedes (Ochlerotatus) fulvus (Wiedemann) and Ae. (Och.) serratus (Theobald)

Humans , Adult , Anopheles/physiology , Anopheles/genetics , Anopheles/immunology , Anopheles/virology , Epidemiology/classification , Epidemiology/history , Epidemiology/trends , Malaria , Public Health
Rev. biol. trop ; 58(2): 777-787, jun. 2010. mapas, tab
Article in Spanish | LILACS | ID: lil-638040


Larval seasonality of the mosquito Anopheles aquasalis (Diptera: Culicidae) and other insects associated to its habitat in Sucre, Venezuela. Anopheles aquasalis Curry is considered the main vector of human malaria in Northern Venezuela. A longitudinal study was carried out in the coastal areas of the Paria Peninsula, Sucre state. The larval habitats of A. aquasalis were classified as: 1- Brackish mangrove, and 2- Freshwater herbaceous swamp. Field surveys of mosquito larvae and aquatic insects were carried out in the same breeding sites over a one-year period, between January and December 1999. At each site, 30 samples of Anopheles larvae and aquatic insects were taken monthly. Simultaneously with mosquito larvae sampling, five selected variables of water were measured: conductivity, salinity, dissolved oxygen, temperature and pH. Seasonal and temporal variations of A. aquasalis larvae and aquatic insects were determined in the two larval habitats. For the entire study period, the abundance of larvae was higher in the mangrove. Correspondence analysis showed a strong relation between some chemical factors of water and larval abundance. The abundance of A. aquasalis larvae in both seasons, was positively correlated with water salinity, pH and conductivity, and negatively with dissolved oxygen in the dry season. The presence of larvae was positively correlated with the presence of Avicenia germinans. In the mangrove there was a positive association between larvae abundance and Scirtidae family abundance and a negative correlation between larvae abundance and monthly precipitation (Spearman), as well as a significant negative correlation between Gerridae abundance and monthly precipitation. In the herbaceous swamp, there were not significant associations between A. aquasalis larvae abundance and abundance of others aquatic insects associated to habitat. Rev. Biol. Trop. 58 (2): 777-787. Epub 2010 June 02.

Anopheles aquasalis es considerado como el principal vector de malaria humana en el norte de Venezuela. El estudio longitudinal se llevó a cabo en áreas costeras de la Península de Paria, estado Sucre. El hábitat de las larvas de A. aquasalis fue clasificado como: manglar salobre y pantano herbáceo. Muestreos para recolectar larvas de mosquitos e insectos asociados se realizaron mensualmente en ambos criaderos desde enero hasta diciembre de 1999 (30 muestras). Simultáneamente se midieron cinco variables seleccionadas del agua: conductividad, salinidad, oxígeno disuelto, temperatura y pH. En ambos criaderos de determinaron las variaciones estacionales y temporales de las larvas de A. aquasalis e insectos acuáticos. Para el período de estudio, la abundancia de larvas fue mayor en el manglar. El análisis de correspondencia mostró una fuerte relación entre algunos factores químicos del agua y la abundancia de las larvas. La abundancia de las larvas de A. aquasalis en ambas épocas, se correlacionó positivamente con la salinidad del agua, pH y conductividad, y negativamente con el oxígeno disuelto, en la estación seca. La presencia de larvas se correlacionó positivamente con la presencia de Avicennia germinans. En el manglar existió una asociación positiva entre la abundancia de larvas y la abundancia de la familia Scirtidae y una correlación negativa entre la abundancia de larvas y la precipitación mensual (Spearman), así como una correlación negativa significativa entre la abundancia de Gerridae y la precipitación mensual. En el pantano herbáceo, no había asociaciones significativas entre la abundancia de las larvas de A. aquasalis y la abundancia de otros insectos acuáticos asociados al hábitat.

Animals , Anopheles/physiology , Coleoptera/physiology , Ecosystem , Hemiptera/physiology , Insect Vectors/physiology , Seasons , Anopheles/classification , Coleoptera/classification , Fresh Water/analysis , Hemiptera/classification , Insect Vectors/classification , Larva , Longitudinal Studies , Venezuela
Neotrop. entomol ; 39(2): 282-288, mar.-abr. 2010. tab
Article in English | LILACS | ID: lil-547693


We analyzed the reproductive status, ovarian development, daily survival rate, and length of the gonotrophic cycle in females of Anopheles ( Kerteszia ) cruzii Dyar & Knab, to determine how these factors influence the risk of malaria transmission in the coastal region of the state of Paraná, southern Brazil. In the Palmito State Forest, Paranaguá, females were captured at dawn and dusk by aspiration, bimonthly from December 2006 through March 2007. A total of 2,268 females were captured, of which 454 were dissected. Of these, 48 percent were parous, 50 percent not reproductive, 73 percent in Christopher and Mer stages I and II, 23 percent in stages III to V, 55 percent nulliparous, 14 percent uniparous, and 11 percent had blood in their midgut. Daily survival was 0.24 ± 0.03 overall, 0.51 ± 0.04 for females captured at dusk, and 0.25 ± 0.03 for those captured at dawn. The Davidson equation for calculation of the gonotrophic cycle was inadequate for An. cruzii populations. Females captured at dusk had a higher survival rate than those from dawn, which means that more females of the dusk population enter the parasite extrinsic cycle. The continuous activity and abundance of A. cruzii in the Palmito State Forest suggests that the conditions are very favorable for its development, with a potential for participation in the protozoan's transmission cycle.

Animals , Female , Anopheles/physiology , Age Factors , Brazil , Longevity , Trees
Neotrop. entomol ; 38(5): 624-631, Sept.-Oct. 2009. ilus
Article in English | LILACS | ID: lil-532054


Cell hypertrophy was the first reaction of the gut epithelial cells of Aedes aegypti (L.), Anopheles albitarsis (Lynch-Arribálzaga) and Culex quinquefasciatus (Say) to the toxins of strains 2362 and S1116 of Bacillus sphaericus, as cells had an increase of intracellular secretory activity. Soon after the cell hypertrophy developed, vesicles were formed at the cell apical portion, which detached with the plasma membrane, characterizing a type of apocrine secretion like. The first pathway of contamination of the mosquito larvae by these bacteria is through the gut, by feeding. Depending on the species of Culicidae and on the bacterial strain used, the hypertrophy of the gut epithelium occurred between 5 and 15 min after exposure to the contaminated environment. The second aspect observed after hypertrophy was the increase in apocrine secretion. The basophilic vesicles that detached from the cells remained between the peritrophic membrane and the gut lumen, such vesicles were filled with material of unknown nature. The gut posterior region showed secretory activity in both control and treated larvae, being much more intense in bacteria-exposed larvae. There were remarkable differences in the epithelial cell reaction according to the toxins of the two bacterial strains, but C.quinquefasciatus was the most susceptible. Differences in the gut cell reactions to the toxins produced by the two bacterial strains are discussed.

Observou-se hipertrofia das células do epitélio intestinal de Aedes aegypti (L.), Anopheles albitarsis (Lynch-Arribálzaga) e Culex quinquefasciatus (Say) devido ao aumento da atividade secretora intracelular como primeira reação às toxinas das linhagens 2362 e S1116 de Bacillus sphaericus (Neide). Após a hipertrofia epitelial, formaram-se vesículas na porção apical das células, as quais eram compostas de fragmentos de membrana plasmática contendo material de natureza desconhecida em seu interior, caracterizando um tipo de secreção apócrina. A via de contaminação das larvas dos mosquitos por essas bactérias é pelo intestino, através da alimentação. Dependendo da espécie de Culicidade e da linhagem bacteriana utilizada, a hipertrofia do epitélio ocorreu entre 5 a 15 min após a exposição das larvas ao meio contaminado. O segundo aspecto observado no processo de contaminação foi o aumento da atividade de secreção apócrina. As vesículas basófilas que se desprendiam das células permaneciam entre a membrana peritrófica e o lúmen intestinal. Observou-se atividade secretora tanto no grupo controle como no experimental, porém muito mais intensa no grupo experimental. Os Culicidae estudados apresentaram diferenças marcantes nas respostas às toxinas das bactérias utilizadas, sendo C. quinquefasciatus a espécie mais suscetível. As diferenças de reações das células em relação às toxinas produzidas pelas duas linhagens bacterianas são discutidas.

Animals , Aedes/physiology , Anopheles/physiology , Apocrine Glands , Bacillus , Culex/physiology , Epithelial Cells , Gram-Positive Bacterial Infections , Apocrine Glands/pathology , Epithelial Cells/pathology , Larva/physiology