Efeitos do alagamento do Rio Paraná na atividade horária de Anopheles (Nyssorhynchus) darlingi Root (Diptera: Culicidae), na divisa dos estados do Mato Grosso do Sul e São Paulo, Brasil

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.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Companhia Energética de São Paul

The influence of the ph and salinity of water in breeding sites on the occurrence and community composition of immature mosquitoes in the green belt of the city of São Paulo, Brazil

The physicochemical parameters of water, such as pH, salinity, conductivity, and total dissolved solids, can influence mosquito larval development, survival, and abundance. Therefore, it is important to elucidate how these factors influence mosquito occurrence. We hypothesized that the occurrence and community composition of immature mosquito species are driven not only by the availability of suitable aquatic habitats, but also by the physicochemical factors of these habitats. The primary objective of this study was therefore to investigate the influence of the physicochemical parameters of water in different types of aquatic habitats on the occurrence of mosquito species in two remnants of Atlantic Forest in the city of São Paulo, Brazil. Collections of immature mosquitoes and assessment of the physicochemical characteristics of the water in the collection sites were car-ried out for twelve months. The variation in species composition and occurrence with the measured physicochemical parameters and the type of breeding site was assessed using constrained ordination methods. The results indicate that there was a statistically significant difference in species composition as a function of the different types of aquatic habitats, and that pH had an influence on species occurrence even when the variance explained by the type of aquatic habitat was removed from the analysis. There was a statistically significant association between mosquito species occurrence and pH and salinity, and the former had a significant influence on the mosquito species collected regardless of the type of aquatic habitat, showing that the pH of the breeding site water is an important factor in driving mosquito population dynamics and species distribution

Feeding habits of mosquitoes (Diptera: Culicidae) in an area of sylvatic transmission of yellow fever in the state of São Paulo, Brazil

Abstract\ud \ud Background\ud The reintroduction of sylvatic yellow fever in the state of São Paulo after about six decades was confirmed in the Northwestern region in 2000, where in 2008 there also occurred an important epizootic. The purpose of this study was to investigate the feeding habits of culicids potentially involved in the sylvatic transmission of the virus in this region.\ud \ud \ud Methods\ud Specimens were collected in 24 forested localities at ground level with hand nets and mouth aspirators. Collections were made quarterly between October 2006 and July 2008 during daylight hours. Blood-meal identification was carried out in mosquitoes of the tribes Aedini, Mansoniini and Sabethini. The biotin/avidin sandwich ELISA was employed to determine six source types: bird, bovine, equine, rat, human and monkey.\ud \ud \ud Results\ud A total of 24,879 females of the three tribes were obtained, 245 (0.98%) of which were engorged. The presence of three different blood sources per engorged female was the predominant situation, and included 35.10% of the total of samples processed. Samples with two or four different sources were represented by 25.31% and 25.71%, of the specimens, respectively, while just 9.39% had only one type and 1.22%, five different sources. Aedes scapularis, Ae. serratus (Group), Psorophora albigenu and Ps. ferox were the most abundant species and accounted for about 95% of the engorged specimens. Of the principal vector species, Haemagogus janthinomys/capricornii was found with bird, bovine and primate blood. These sources were predominant and alternated top ranking as the most frequent source according to the mosquito species and collection site. In general, primate blood was the most prevalent source.\ud \ud \ud Conclusions\ud The human population of the region visits this ecotone frequently, which indicates the need for the periodical assessment of vaccination coverage against yellow fever. The frequency of non-human primate blood source in mosquito species that show minor vector importance in yellow fever virus transmission deserves attention. The eclectic feeding habits and some aspects of the interactions between potential vectors and reservoirs of yellow fever may be associated with the habitat fragmentation characteristic of the region. We recommend that further studies on the capacity and vector competence be performed on secondary vectors in extra-Amazonian region

Ecology of Anopheles darlingi, Root (1926) in Porto Primavera's reservoir, São Paulo and Mato Grosso do Sul States.

Problemas de saúde pública advindos da proliferação de vetores de agentes patogênicos são frequentemente relatados após a construção de grandes barragens nas regiões tropicais. Porto Primavera é um dos últimos grandes projetos hidrelétricos implementados no Brasil, abrangendo uma faixa de cerca 200 km do Rio Paraná, entre os Estados de São Paulo e Mato Grosso do Sul. Resultados preliminares de projetos de pesquisa desenvolvidos na região desde 1997 apontam para um aumento na densidade de Anopheles darlingi, coincidindo com uma intensificação dos fluxos e atividades humanas na área, como turismo, pesca e transporte. Diante disso, a preocupação com a ocorrência de surtos de malária nas localidades à margem do lago motivou a busca de um maior conhecimento sobre as populações destes vetores. O objetivo desta pesquisa foi investigar a associação entre a abundância das formas imaturas e adultas de An. darlingi com variáveis do microhabitat e da ecologia da paisagem (respectivamente), após a formação do reservatório. Em relação ao microhabitat, foram selecionados o pH, condutividade, o sombreamento, a presença de cianofíceas filamentosas, detritos flutuantes, matéria orgânica galhos ou raízes e a composição das assembléias de macrófitas aquáticas. Quanto à ecologia da paisagem, foram analisados o comprimento da borda abrigo-criadouro e o tamanho das áreas dos habitats através das técnicas de sensoriamento remoto e SIG. Para a verificação de associações entre variáveis do microhabitat e imaturos de An. darlingi foi empregada a análise de correspondência canônica e para as métricas da paisagem e formas adultas, a regressão linear simples. As formas imaturas de An. darlingi apresentaram associação positiva com todas as variáveis do microhabitat, exceto com a abundância de cianofíceas filamentosas. As associações mais fortes se deram na seguinte ordem: abundância de Wolffia sp. e profundidade no primeiro eixo canônico e presença de material flutuante tipo II, pH e grupo de macrófitas e componentes da superfície no segundo eixo. Foi encontrada associação positiva entre abundância de espécimes adultos de An. darlingi e o comprimento da borda fragmento florestal-coleção hídrica, mas não em relação às áreas dos fragmentos florestais. De acordo com estes resultados, novos referenciais teóricos podem ser aplicados no mapeamento do risco da transmissão da malária em escala regional e na vigilância e controle entomológicos em nível local.Public Health problems raised up from vector-borne diseases proliferation are frequently related after the construction of big dams in tropical regions. Porto Primavera is one of these greats hydroeletric projects stabilished recently in Brazil, occuping aproximately 200 km of Paraná river between São Paulo and Mato Grosso do Sul States. Preliminary results on developping investigations up to 1997 showed an Anopheles darlingi increase simultaneously the intensification of human moviment and activities in region, such as turism, fishing and transport. In face to the worry about the possibility of occurrence of malaria outbreaks in localities around the Lake raised the motivation to investigate a better knowledge about the populations of this vectors. In general, the objective was to investigate the association between the abundances of immatures and adult forms of Anopheles darlingi with microhabitat variables and landscape ecology respectively, after filling the reservoir. In relation to microhabitat variables was selected: pH, condutivity, shadow, deep, presence of filamentous cianoficeas, floating debris, and composition of aquatic macrophytes. In relation to landscape ecology it was analysed the perimeter of the florested shelters and breeding sites-edge and the area of florestal fragments, based on remote sensing and GIS technologies. Cannonical Correspondance analysis was the method to verify the association between microhabitat variables and immatures abundance. A large distribution of An. darlingi was noted because was find in all surveyed locations. Immature forms it was be positively associated with all microhabitat variables except filamentous cianoficea. The strongly association were in order: Wolffia sp. and deep to the first cannonical axis and floating debris of Type II, pH and macrophytes groups and surface components for the second. The Simple Linear Regression was the method to verify associations between landscape ecology variables and adult forms was find positive association between the abundance of An. darlingi and the perimeter of the florested shelters and breeding sites-edge, but not to the area of florestal fragments. According to this results, new theoretical knowledges are able to apply in the risk maps elaboration for malaria transmission in regional scale and to enthomological vigilance and control in local scale

A mathematical model for zoonotic transmission of malaria in the Atlantic Forest: Exploring the effects of variations in vector abundance and acrodendrophily.

Transmission foci of autochthonous malaria caused by Plasmodium vivax-like parasites have frequently been reported in the Atlantic Forest in Southeastern and Southern Brazil. Evidence suggests that malaria is a zoonosis in these areas as human infections by simian Plasmodium species have been detected, and the main vector of malaria in the Atlantic Forest, Anopheles (Kerteszia) cruzii, can blood feed on human and simian hosts. In view of the lack of models that seek to predict the dynamics of zoonotic transmission in this part of the Atlantic Forest, the present study proposes a new deterministic mathematical model that includes a transmission compartment for non-human primates and parameters that take into account vector displacement between the upper and lower forest strata. The effects of variations in the abundance and acrodendrophily of An. cruzii on the prevalence of infected humans in the study area and the basic reproduction number (R0) for malaria were analyzed. The model parameters are based on the literature and fitting of the empirical data. Simulations performed with the model indicate that (1) an increase in the abundance of the vector in relation to the total number of blood-seeking mosquitoes leads to an asymptotic increase in both the proportion of infected individuals at steady state and R0; (2) the proportion of infected humans at steady state is higher when displacement of the vector mosquito between the forest strata increases; and (3) in most scenarios, Plasmodium transmission cannot be sustained only between mosquitoes and humans, which implies that non-human primates play an important role in maintaining the transmission cycle. The proposed model contributes to a better understanding of the dynamics of malaria transmission in the Atlantic Forest

Evaluation of Methods for Collecting Mosquitoes (Culicidae: Diptera) in Canopy and Ground Strata in the Brazilian Savanna

The hand-net is the standard method for capturing mosquitoes with sylvatic diurnal activity in disease outbreaks in Brazil. However, occupational risks and biases related to the collectors’ abilities and attractiveness are important limitations. In this study, we compared hand-nets with automatic traps (CDC) associated to CO2 and BG-Lure® in the Vassununga State Park, a Brazilian Savanna protection area. The collections carried out over 27 days on the ground and the forest canopy. A total of 1555 mosquitoes were obtained in 20 taxa. The diversity index ranged between 1.12 and 1.79 and the dominance index from 0.22 to 0.40. The dominant species on the ground was Aedes scapularis (46.0%), and in the canopy, Hg. janthinomys/capricornii (31.9%). Haemagogus leucocelaenus was rare (n = 2). The hand-net resulted in the greatest diversity and abundance of species in both strata, followed by the traps associated with CO2. A low degree of similarity was observed between the hand-net on the ground compared to the other capture methods. The use of BG-Lure® alone resulted in a low number of specimens. In conclusion, the hand-net is still the method of choice for collecting arbovirus vectors in the diurnal period, especially yellow fever vectors

Aedes albopictus em área rural do Brasil e implicações na transmissão de febre amarela silvestre

Durante estudos ecológicos sobre mosquitos anofelíneos no município de Bataguassu, Estado de Mato Grosso do Sul, foram encontradas larvas e adultos de Aedes albopictus. Pela primeira vez sua introdução ocorre numa área enzoótica do vírus selvático da febre amarela no Brasil. Isto sugere risco potencial para transferência desse vírus para área urbana infestada com Aedes aegypti

Effects of anthropogenic landscape changes on the abundance and acrodendrophily of Anopheles (Kerteszia) cruzii, the main vector of malaria parasites in the Atlantic Forest in Brazil

Abstract Background The mosquito Anopheles (Kerteszia) cruzii is the main vector of human and simian malaria in the Atlantic Forest. This species is usually abundant in the forests where it occurs, preferring to live and feed on canopies, behaviour known as acrodendrophily. However, in several studies and locations this species has been observed in high density near the ground in the forest. In this study, it was hypothesized that factors associated with anthropogenic landscape changes may be responsible for the variation in abundance and acrodendrophily observed in An. cruzii. Methods The study was conducted in a conservation unit in the city of São Paulo, Brazil. Monthly entomological collections were performed from March 2015 to April 2017, and the resulting data were used with data from another study conducted in the same area between May 2009 and June 2010. Mosquitoes were collected from five sites using CDC and Shannon traps. Landscape composition and configuration metrics were measured, and generalized linear mixed-effect models were used to investigate the relationship between these metrics and variations in the abundance and acrodendrophily of An. cruzii. Results The model that showed the best fit for the relationship between landscape metrics and An. cruzii abundance suggests that an increase in the proportion of forest cover leads to an increase in the abundance of this mosquito, while the model that best explained variations in An. cruzii acrodendrophily suggests that an increase in total forest-edge length leads to greater activity by this species at ground level. Conclusion While the data indicate that changes in landscape due to human activities lead to a reduction in An. cruzii abundance, such changes may increase the contact rate between this species and humans living on the edges of forest fragments where An. cruzii is found. Future studies should, therefore, seek to elucidate the effect of these landscape changes on the dynamics of Plasmodium transmission in the Atlantic Forest, which according to some studies includes the participation of simian hosts