Aedes (Stegomyia) aegypti L. e a culicideofauna associada em área urbana da região sul, Brasil

Foram mostrados alguns aspectos sobre a ecologia de 11 espécies de Culicidae que procriam em recipientes, em uma área urbana do Sul do Brasil. Os mais variados tipos de recipientes foram listados como eficientes criadouros para larvas de culicídeos. Aedes aegypti apareceu como espécie recém-introduzida e limitada somente a duas áreas da cidade. As espécies predominantes foram: Culex quinquefasciatus, Culex coronator, Aedes aegypti, Aedes fluviatilis e Limatus durhamii.

Criadouros de Aedes (Stegomyia) aegypti (Linnaeus, 1762) em bromélias nativas na Cidade de Vitória, ES

Alguns insetos transmissores de doenças procriam exclusivamente nas proximidades das residências. O Aedes aegypti, responsável por epidemias de dengue em cidades brasileiras, representa sério risco também para a febre amarela. Com o insucesso da campanha de erradicação do inseto, justifica-se a busca de criadouros fora do alcance das medidas de controle atualmente adotadas. Na Cidade de Vitória, ES, investigou-se a ocorrência de criadouros de Aedes aegypti na água coletada em bromélias nativas, sobre as rochas. Paralelamente, avaliou-se a infestação predial nas áreas urbanas contíguas. Em quatro das cinco áreas investigadas foram encontradas larvas de culicídeos nas bromélias, sendo que em duas foi identificado Aedes aegypti. A presença dos criadouros em bromélias não guardou relação com a infestação predial nas áreas próximas. Torna-se necessário definir se os criadouros em bromélias constituem focos primários do Aedes aegypti, ou se representam uma conseqüência da elevada infestação urbana.

Spatial distribution and esterase activity in populations of Aedes (Stegomyia) aegypti (Linnaeus) (Diptera: Culicidae) resistant to temephos

INTRODUCTION:The need for studies that describe the resistance patterns in populations of Aedes aegypti (Linnaeus) in function of their region of origin justified this research, which aimed to characterize the resistance to temephos and to obtain information on esterase activity in populations of Aedes aegypticollected in municipalities of the State of Paraíba.METHODS:Resistance to temephos was evaluated and characterized from the diagnostic dose of 0.352mg i.a./L and multiple concentrations that caused mortalities between 5% and 99%. Electrophoresis of isoenzymes was used to verify the patterns of esterase activity among populations of the vector.RESULTS:All populations of Aedes aegypti were resistant to temephos, presenting a resistance rate (RR) greater than 20. The greatest lethal dose 50% of the sample (CL50) was found for the municipality of Lagoa Seca, approximately forty-one times the value of CL50 for the Rockefeller population. The populations characterized as resistant showed two to six regions of α and β-esterase, called EST-1 to EST-6, while the susceptible population was only seen in one region of activity.CONCLUSIONS:Aedes aegyptiis widely distributed and shows a high degree of resistance to temephos in all municipalities studied. In all cases, esterases are involved in the metabolism and, consequently, in the resistance to temephos.

Ciclo de vida de Aedes (Stegomyia) aegypti (Diptera, Culicidae) em águas com diferentes características

O trabalho teve por objetivo avaliar o efeito da qualidade da água no desenvolvimento de Aedes aegypti (Linnaeus, 1762). O ciclo de vida desse vetor foi estudado em águas de esgoto bruto, efluente de reator UASB, efluente de lagoa de polimento, efluente de filtro anaeróbio, água de chuva e água desclorada. Diariamente avaliaram-se o período de desenvolvimento e as viabilidades de ovo, larva, pupa, longevidade e a fecundidade dos adultos. A duração do período larval variou de 5,6 a 9,1 dias, sendo a sobrevivência baixa em águas de esgoto bruto, efluente de reator UASB, efluente de lagoa de polimento e efluente de filtro anaeróbio. Não foram observadas diferenças nas durações e viabilidades das fases de ovo e pupa, longevidade e fecundidade dos adultos. Constatou-se que, apesar da baixa viabilidade larval, é possível o desenvolvimento do A. aegypti em águas com elevados graus de poluição e que todos os tratamentos permitiram o desenvolvimento desse vetor.

Flutuação populacional e comparação de métodos de coleta de Aedes (Stegomyia) aegypti (Diptera, Culicidae)

Fatores ambientais podem atuar como reguladores da expansão das populações de Aedes aegypti (Linnaeus, 1762). Este trabalho objetivou avaliar a influência da temperatura, umidade relativa do ar, e precipitação pluviométrica na flutuação populacional de Ae. aegypti. A pesquisa foi conduzida em Boqueirão, Campina Grande e Remígio, Estado da Paraíba, compreendendo um período de 12 meses, utilizando-se o método de coleta por armadilha de oviposição e de pesquisa larvária. A flutuação populacional de ovos e de outras formas imaturas, bem como os índices de infestação para ovos e larvas foi correlacionada com os dados climáticos utilizando-se a análise de correlação de Pearson. Os testes do qui-quadrado e de Tukey foram utilizados para comparar a infestação entre as áreas de estudo e a eficiência entre os métodos de pesquisas com armadilha de oviposição e de coletas de larvas. Não foram encontradas correlações entre as variáveis climáticas e a flutuação populacional de Ae. aegypti, nem com os índices para armadilha de oviposição (IAO) e de Breteau (IB). O IAO foi considerado alto, com média de 54,9; 59,53 e 59,51%, enquanto que o IB foi muito baixo com média de 1,55, 1,69 e 3,64, para os municípios de Boqueirão, Campina Grande e Remígio, respectivamente. A análise do qui-quadrado para o número de imóveis positivos foi altamente significativa, podendo-se inferir que o método de coleta por armadilha de oviposição foi mais eficiente que a pesquisa larvária na detecção da infestação pelo Ae. aegypti. Os resultados indicam que os fatores avaliados não podem ser considerados isolados na análise ecológica da distribuição desta espécie, já que não foram estabelecidas correlações entre a presença do vetor e fatores climático, como temperatura, umidade relativa do ar e precipitação pluviométrica. Assim na análise ecológica da distribuição do Ae. aegypti deve ser considerados os múltiplos fatores condicionantes e determinantes da sua infestação.

Experimental Infection of Culex (Culex) quinquefasciatus and Aedes (Stegomyia) aegypti with Wuchereria bancrofti

A study was conducted to determine the susceptibility of local strains of Culex quinquefasciatus and Aedes aegypti to infection with the strain of Wuchereria bancrofti that occurs in Maceió, State of Alagoas, Brazil. Cx. quinquefasciatus blood fed simultaneously on the same microfilariae carrier ingested more blood and 2-3x more microfilariae than Ae. aegypti. Survival rates of both species of insects living for 21 days after blood feeding on microfilaraemic patients were not significantly different from the survival rates of mosquitoes that blood fed on amicrofilaraemic individuals. W. bancrofti parasites underwent normal development in Cx. quinquefasciatus, with third stage larvae first being recorded on the 11th day post infection, and their numbers increasing thereafter. Development of filariae in Ae. aegypti did not proceed beyond the first larval stage, and there was a progressively increasing number of non-viable larvae with the passage of time. It is concluded that Ae. aegypti is not involved in the transmission of W. bancrofti in Maceió.

Oviposition activity and seasonal pattern of a population of Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) in subtropical Argentina

Monthly oviposition activity and the seasonal density pattern of Aedes aegypti were studied using larvitraps and ovitraps during a research carried out by the Public Health Ministry of Salta Province, in Tartagal, Aguaray and Salvador Mazza cities, in subtropical Argentina. The A. aegypti population was active in both dry and wet seasons with a peak in March, accordant with the heaviest rainfall. From May to November, the immature population level remained low, but increased in December. Ae. aegypti oviposition activity increased during the fall and summer, when the relative humidity was 60% or higher. Eggs were found in large numbers of ovitraps during all seasons but few eggs were observed in each one during winter. The occurrence and the number of eggs laid were variable when both seasons and cities were compared. The reduction of the population during the winter months was related to the low in the relative humidity of the atmosphere. Significant differences were detected between oviposition occurrences in Tartagal and Aguaray and Salvador Mazza cities, but no differences in the number of eggs were observed. Two factors characterize the seasonal distribution pattern of Ae. aegypti in subtropical Argentina, the absence of a break during winter and an oviposition activity concomitant of the high relative humidity of the atmosphere.

Identification of the best ovitrap installation sites for gravid Aedes (Stegomyia) aegypti in residences in Mirassol, state of São Paulo, Brazil

This study aimed at identifying the best ovitrap installation sites for gravid Aedes aegypti in Mirassol, state of São Paulo, Brazil. Ovitraps were installed in ten houses per block over ten blocks. Four ovitraps were placed per residence, one in the bedroom, one in the living room, and two outdoors with one in a sheltered area and one in an outside site. Each week for eleven weeks, visits were made to examine the ovitraps and to change the paddles used for egg-laying. Eggs were analyzed according to the trap location. The results showed that the outdoor sites received significantly more oviposition than indoor sites. Additionally, in respect to the outdoor sites, the outside site received significantly more oviposition than the sheltered site. A b correlation was observed between positive traps and egg numbers. The results are discussed with respect to the best installation site of the traps and their implications in surveillance and control of dengue vectors.

Genetic lineages in the yellow fever mosquito Aedes (Stegomyia) aegypti (Diptera: Culicidae) from Peru

The yellow fever mosquito Aedes aegypti was introduced in Peru in 1852 and was considered to be eradicated in 1958. In 2001, Ae. aegypti had been recorded in 15 out of 24 Peruvian Departments. Peru has great ecological differences between the east and west sides of Andes. Because of this, we consider that Ae. aegypti populations of both east and west sides can have a genetically distinct population structure. In this study we examined genetic variability and genealogical relationships among three Ae. aegypti Peruvian populations: Lima, Piura (west Andes), and Iquitos (east Andes) using a fragment of the ND4 gene of the mitochondrial genome. Three haplotypes were detected among 55 samples. Lima and Iquitos showed the same haplotype (Haplotype I), whereas Piura has two haplotypes (Haplotype II and III). Haplotype II is four mutational steps apart from Haplotype I, while Haplotype III is 13 mutational steps apart from Haplotype I in the network. The analysis of molecular variation showed that mostly of the detected genetic variation occurs at interpopulational level. The significant value phist suggests that Piura population is structured in relation to Lima and Iquitos populations and the gene flow of the ND4 is restricted in Piura when compared to Lima and Iquitos. Genetic relationship between haplotype I and haplotype II suggests introduction of the same mtDNA lineage into those localities. However the existence of a genetically distant haplotype III also suggests introduction of at least two Ae. aegypti lineages in Peru.

Study of the relationship between Aedes (Stegomyia) aegypti egg and adult densities, dengue fever and climate in Mirassol, state of São Paulo, Brazil

The purpose of this study was to examine the relationship between Aedes aegypti egg and adult density indices, dengue fever and climate in Mirassol, state of São Paulo, Brazil, between November 2004-November 2005. Weekly collections of adults and eggs were made using, respectively, manual aspirators and oviposition traps that produced four entomological indices (positivity and average of females and eggs). Weekly incidence coefficients were calculated based on dengue cases. Each week, the data obtained from entomological indices were related to each other, dengue, and climate variables. The first index to show an association with dengue transmission was the female average, followed by female positivity and egg average. Egg positivity did not show a relationship with risk for dengue, but was sensitive to identifying the presence of the vector, principally in dry seasons. The relationship between climatic factors, the vector and the disease found in this study can be widely employed in planning and undertaking dengue surveillance and control activities, but it is a tool that has not been considered by the authorities responsible for controlling the disease. In fact, this relationship permits the use of information about climate for early detection of epidemics and for establishing more effective prevention strategies than currently exist.

Laboratory and field evaluation of the effects of the neonicotinoid imidacloprid on the oviposition response of Aedes (Stegomyia) aegypti Linnaeus (Diptera: Culicidae)

In this paper, we assessed the suitability of using the neonicotinoid imidacloprid with standard ovitraps by evaluating the ovicidal properties of imidacloprid and its influence on the oviposition response of gravid females of Aedes (Stegomyia) aegypti Linnaeus (Diptera: Culicidae). First, we calculated the imidacloprid lethal dose 99 (LD99) by exposing third instar larvae of the target species to different concentrations of the insecticide. Next, Ae. aegypti eggs were exposed to the imidacloprid LD99 for 24 h and hatching inhibition was recorded. Finally, we investigated any potential repellent effect of the imidacloprid solution on the oviposition response of gravid Aedes females in field and laboratory conditions. The LD99 obtained from larvae tests proved to be sufficient to keep any exposed eggs from hatching. No repellent effect was observed; females laid as many eggs in imidacloprid-treated ovitraps as in traps containing either clean water or temephos-treated water in both field and laboratory conditions. Our results indicate that imidacloprid is a suitable insecticide for treating ovitraps against Ae. aegypti.

A comparison of larval, ovitrap and MosquiTRAP surveillance for Aedes (Stegomyia) aegypti

In Brazil, the entomological surveillance of Aedes (Stegomyia) aegypti is performed by government-mandated larval surveys. In this study, the sensitivities of an adult sticky trap and traditional surveillance methodologies were compared. The study was performed over a 12-week period in a residential neighbourhood of the municipality of Pedro Leopoldo, state of Minas Gerais, Brazil. An ovitrap and a MosquiTRAP were placed at opposite ends of each neighbourhood block (60 traps in total) and inspections were performed weekly. The study revealed significant correlations of moderate strength between the larval survey, ovitrap and MosquiTRAP measurements. A positive relationship was observed between temperature, adult capture measurements and egg collections, whereas precipitation and frequency of rainy days exhibited a negative relationship.

Dynamics of the control of Aedes (Stegomyia) aegypti Linnaeus (Diptera, Culicidae) by Bacillus thuringiensis var israelensis, related with temperature, density and concentration of insecticide

The dynamics of the control of Aedes (Stegomyia) aegypti Linnaeus, (Diptera, Culicidae) by Bacillus thuringiensis var israelensis has been related with the temperature, density and concentration of the insecticide. A mathematical model for biological control of Aedes aegypti with Bacillus thuringiensis var israelensis (Bti) was constructed by using data from the literature regarding the biology of the vector. The life cycle was described by differential equations. Lethal concentrations (LC50 and LC95) of Bti were determined in the laboratory under different experimental conditions. Temperature, colony, larvae density and bioinsecticide concentration presented marked differences in the analysis of the whole set of variables; although when analyzed individually, only the temperature and concentration showed changes. The simulations indicated an inverse relationship between temperature and mosquito population, nonetheless, faster growth of populations is reached at higher temperatures. As conclusion, the model suggests the use of integrated control strategies for immature and adult mosquitoes in order to achieve a reduction of Aedes aegypti.

Aedes (Stegomyia) albopictus (SKUSE), su asociación con Aedes (Stegomyia) aegypti (LINNAEUS) y otros culícidos en Allende, N.L., México [por] Juan de Dios Aguilar Gueta

Tesis (Maestría en Ciencias con Especialidad en Entomología Médica) U.A.N.L.

Distribuição espacial de criadouros de Aedes (Stegomyia) aegypti Linnaeus 1762 (Diptera: Culicidae) em pontos georreferenciados de dois bairros da cidade de Macapá-AP: área endêmica de dengue

O presente trabalho teve como objetivo estudar a distribuição espacial dos criadouros de Aedes (Stegomyia) aegypti Linnaeus 1762 Diptera: Culicidae) em pontos georreferenciados de dois bairros da cidade de Macapá-AP. Os espécimes foram coletados em dois períodos (seco e chuvoso) e analisados qualitativa e quantitativamente. Realizou-se mapeamento dos imóveis inspecionados, destacando-se aqueles com criadouros positivos para formas imaturas de A. aegypti, além de entrevistas com os residentes locais, a fim de se avaliar aspectos sócio-econômicos relacionados à ocorrência da espécie em questão. No bairro do Trem os depósitos móveis, detiveram 21,90% das larvas coletadas no período seco e 24,60% no período chuvoso; depósitos fixos 22,38% no período seco e 20,59% no período chuvoso; e depósitos removíveis 49,05% no período seco e 48,93% no período chuvoso. No Bairro Cidade Nova as fossas e depósitos de água para consumo, detiveram 26,79% e 18,66% no período seco respectivamente. No período chuvoso, os depósitos de água para consumo subiram para 34,16 %, as fossas se mantiveram inalteradas, sugerindo que esse último seja considerado um recipiente preferencial para a desova do mosquito. Constatou-se que o abastecimento de água encanada cobre 93% das residências do bairro do Trem, e 73% do bairro Cidade Nova, o qual não dispõe de rede de esgoto sanitário. No bairro do Trem houve variabilidade regular na distribuição dos criadouros nos dois períodos estudados. No bairro Cidade Nova o comportamento espacial apresentou uma tendência de variabilidade irregular, sendo possível caracterizar as áreas de risco existentes em relação ao tipo de criadouro. De modo geral, conclui-se que uma das grandes capacidades da análise de dados georeferenciados é a sua manipulação para produzir novas informações que contribuam para uma melhor gestão das medidas de controle.