RESUMO
Mosquitoes of the genus Sabethes are exclusively sylvatic species occurring in Central and South Americas, where they play a role in the transmission of arbovirus. Sabethes identicus, a common bamboo-breeder species, has been found naturally infected with yellow fever virus. Our study aimed to describe biological and behavioral features of Sa. identicus in the laboratory, as well as establish and standardize an isolated colony for experimental assays. We tested different larval densities and evaluated larval and pupal development time, oviposition behavior, egg production, and longevity. We also shot and video-documented bionomics and behavioral aspects of the mosquitoes in the field and laboratory. A colony with more than 30 generations was achieved. Embryogenesis of Sa. identicus is completed in about three days with a 79% hatch rate, while larval and pupal development takes approximately 15-17 and nine days, respectively. The mosquito's entire life cycle lasts approximately 30 days. Adult females could survive 71 days, and each individual laid an average of 88 eggs over their lifetime; 50% of females and males survived 37 and 24 days, respectively. Hematophagy peaks as early as the first week of emergence. The net content of a bamboo internode influenced the choice for oviposition, with the average number of eggs laid in those containing rearing water with larval and pupal exuviae being significantly higher than when they had only dechlorinated water or water with yeast. We documented for the first time an ecological association of weevils and Sa. identicus, where the oviposition of the latter depends on the weevil creating a hole in the bamboo wall for egg-laying purposes. Video recordings revealed for the first time the peculiar movements of gravid females during egg-throwing into tiny bamboo holes, as well as the laborious escape of newly emerged adults from the bamboo cavity, and mating behavior.
Assuntos
Culicidae , Animais , Masculino , Feminino , Oviposição , Larva , Meio Ambiente , ÁguaRESUMO
Resumo As coleções e pesquisas feitas nas primeiras décadas do século XX, no Rio de Janeiro, foram fundamentais para o estudo da sistemática e da história natural dos mosquitos no Brasil. Um personagem de destaque nesse cenário foi Antonio Gonçalves Peryassú. Analisamos o histórico de uma coleção por ele organizada no Museu Nacional do Rio de Janeiro, entre 1918 e 1922.
Abstract Collections formed and studies conducted in the early decades of the twentieth century in Rio de Janeiro, Brazil, were crucial for the study of the systematization and natural history of mosquitoes in Brazil. One key figure in this context was Antonio Gonçalves Peryassú. The history of a collection he organized at Museu Nacional [National Museum] in Rio de Janeiro between 1918 and 1922 is analyzed.
Assuntos
Coleção , Entomologia , Culicidae , Brasil , História do Século XXRESUMO
BACKGROUND In Brazil, the Yellow Fever virus (YFV) is endemic in the Amazon, from where it eventually expands into epidemic waves. Coastal south-eastern (SE) Brazil, which has been a YFV-free region for eight decades, has reported a severe sylvatic outbreak since 2016. The virus spread from the north toward the south of the Rio de Janeiro (RJ) state, causing 307 human cases with 105 deaths during the 2016-2017 and 2017-2018 transmission seasons. It is unclear, however, whether the YFV would persist in the coastal Atlantic Forest of RJ during subsequent transmission seasons. OBJECTIVES To conduct a real-time surveillance and assess the potential persistence of YFV in the coastal Atlantic Forest of RJ during the 2018-2019 transmission season. METHODS We combined epizootic surveillance with fast diagnostic and molecular, phylogenetic, and evolutionary analyses. FINDINGS Using this integrative strategy, we detected the first evidence of YFV re-emergence in the third transmission season (2018-2019) in a dying howler monkey from the central region of the RJ state. The YFV detected in 2019 has the molecular signature associated with the current SE YFV outbreak and exhibited a close phylogenetic relationship with the YFV lineage that circulated in the same Atlantic Forest fragment during the past seasons. This lineage circulated along the coastal side of the Serra do Mar mountain chain, and its evolution seems to be mainly driven by genetic drift. The potential bridge vector Aedes albopictus was found probing on the recently dead howler monkey in the forest edge, very close to urban areas. MAIN CONCLUSIONS Collectively, our data revealed that YFV transmission persisted at the same Atlantic Forest area for at least three consecutive transmission seasons without the need of new introductions. Our real-time surveillance strategy permitted health authorities to take preventive actions within 48 h after the detection of the sick non-human primate. The local virus persistence and the proximity of the epizootic forest to urban areas reinforces the concern with regards to the risk of re-urbanisation and seasonal re-emergence of YFV, stressing the need for continuous effective surveillance and high vaccination coverage in the SE region, particularly in RJ, an important tourist location.
Assuntos
Febre Amarela/terapia , Sistemas de Transporte de Aminoácidos , Mosquitos Vetores/patogenicidade , Alouatta , FilogeografiaRESUMO
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.
Assuntos
Animais , Oviposição , Malária/transmissão , Anopheles/classificação , Anopheles/fisiologia , Mosquitos Vetores , Anopheles/parasitologiaRESUMO
We discuss the complex eco-social factors involved in the puzzle of the unexpected rapid viral spread in the ongoing Brazilian yellow fever (YF) outbreak, which has increased the reurbanisation risk of a disease without urban cases in Brazil since 1942. Indeed, this rapid spatial viral dissemination to the Southeast and South regions, now circulating in the Atlantic Forest fragments close to peri-urban areas of the main Brazilian megalopolises (São Paulo and Rio de Janeiro) has led to an exponential increase in the number of yellow fever cases. In less than 18 months, 1,833 confirmed cases and 578 deaths were recorded most of them reported in the Southeast region (99,9%). Large epizooties in monkeys and other non-human primates (NHPs) were communicated in the country with 732 YF virus (YFV) laboratory confirmed events only in the 2017/2018 monitoring period. We also discuss the peculiarities and similarities of the current outbreak when compared with previous great epidemics, examining several hypotheses to explain the recent unexpected acceleration of epizootic waves in the sylvatic cycle of the YFV together with the role of human, NHPs and mosquito mobility with respect to viral spread. We conclude that the most feasible hypothesis to explain this rapidity would be related to human behavior combined with ecological changes that promoted a significant increase in mosquito and NHP densities and their contacts with humans. We emphasize the urgent need for an adequate response to this outbreak such as extending immunisation coverage to the whole Brazilian population and developing novel strategies for immunisation of NHPs confined in selected reserve areas and zoos. Finally, we stress the urgent need to improve the quality of response in order to prevent future outbreaks and a catastrophic reurbanisation of the disease in Brazil and other South American countries. Continuous monitoring of YFV receptivity and vulnerability conditions with effective control of the urban vector Aedes aegypti and significant investments in YF vaccine production capacity and research and development for reduction of adverse effects are of the highest priority.
Assuntos
Humanos , Febre Amarela/diagnóstico , Febre Amarela/terapia , Febre Amarela/transmissão , Imunização/métodos , AedesRESUMO
BACKGROUND Zika has emerged as a new public health threat after the explosive epidemic in Brazil in 2015. It is an arbovirus transmitted mainly by Aedes aegypti mosquitoes. The knowledge of physiological, behavioural and biological features in virus-infected vectors may help the understanding of arbovirus transmission dynamics and elucidate their influence in vector capacity. OBJECTIVES We aimed to investigate the effects of Zika virus (ZIKV) infection in the behaviour of Ae. aegypti females by analysing the locomotor activity, egg production and viability. METHODOLOGY Ae. aegypti females were orally infected with ZIKV through an artificial feeder to access egg production, egg viability and locomotor activity. For egg production and viability assays, females were kept in cages containing an artificial site for oviposition and eggs were counted. Locomotor activity assays were performed in activity monitors and an average of 5th, 6th and 7th days after infective feeding was calculated. FINDINGS No significant difference in the number of eggs laid per females neither in their viability were found between ZIKV infected and non-infected females, regardless the tested pair of mosquito population and virus strain and the gonotrophic cycles. Locomotor activity assays were performed regardless of the locomotor activity in ZIKV infected females was observed, in both LD and DD conditions. MAIN CONCLUSIONS The lower locomotor activity may reduce the mobility of the mosquitoes and may explain case clustering within households reported during Zika outbreaks such as in Rio de Janeiro 2015. Nevertheless, the mosquitoes infected with ZIKV are still able to disseminate and to transmit the disease, especially in places where there are many oviposition sites.
Assuntos
Animais , Zika virus , Infecção por Zika virus/diagnóstico , Infecção por Zika virus/terapia , Infecção por Zika virus/transmissão , AedesRESUMO
Zika virus (ZIKV) is widely distributed in Brazil and the Northeast Region (NE) is the most affected zone, showing the highest incidence of microcephaly associated with ZIKV congenital infections worldwide. We report attempts to infect three populations of Culex quinquefasciatus from severely affected sites in the NE and Southeast Region (SE) of Brazil with three strains of ZIKV isolated from these localities. An Aedes aegypti population from the SE was used as a positive control. All tested Cx. quinquefasciatus populations were refractory to the ZIKV isolates. For these reasons, we believe Cx. quinquefasciatus should not be considered a potential vector of ZIKV in Brazil.
Assuntos
Animais , Saliva/virologia , Culex/virologia , Zika virus/isolamento & purificação , Infecção por Zika virus/transmissão , Infecção por Zika virus/epidemiologia , Mosquitos Vetores/virologia , Microcefalia/epidemiologia , Microcefalia/virologia , Brasil/epidemiologiaRESUMO
This article discusses the peculiar conditions that favoured the unexpected introduction of Zika virus into the poorest northeastern region of Brazil in 2015, its speed of transmission to other Brazilian states, other Latin American countries and other regions, and the severity of related neurological disorders in newborns and adults. Contrasting with evidence that Zika had so far caused only mild cases in humans in the last six decades, the epidemiological scenario of this outbreak in Brazil indicates dramatic health effects: in 2015, an increase of 20-fold in notified cases of microcephaly and/or central nervous system (CNS) alterations suggestive of Zika congenital infection, followed by an exponential increase in 2016, with 2366 cumulative cases confirmed in the country by the end of December 2016. A significant increase in Guillain-Barré syndrome in adults has also been reported. Factors involved in viral dissemination, neural pathogenesis and routes of transmission in Brazil are examined, such as the role of social and environmental factors and the controversies involved in the hypothesis of antibody-dependent enhancement, to explain the incidence of congenital Zika syndrome in Brazil. Responses to the Zika outbreak and the development of new products are also discussed.
Assuntos
Feminino , Gravidez , Recém-Nascido , Complicações na Gravidez/virologia , Dengue/imunologia , Dengue/epidemiologia , Infecção por Zika virus/complicações , Infecção por Zika virus/imunologia , Infecção por Zika virus/transmissão , Microcefalia/virologia , Brasil/epidemiologia , Surtos de Doenças , Notificação de Doenças , Análise EspacialRESUMO
The geographical distribution of Aedes albopictus in Brazil was updated according to the data recorded across the country over the last eight years. Countrywide house indexes (HI) for Ae. albopictus in urban and suburban areas were described for the first time using a sample of Brazilian municipalities. This mosquito is currently present in at least 59% of the Brazilian municipalities and in 24 of the 27 federal units (i.e., 26 states and the Federal District). In 34 Brazilian municipalities, the HI values for Ae. albopictus were higher than those recorded for Ae. aegypti, reaching figures as high as HI = 7.72 in the Southeast Region. Remarks regarding the current range of this mosquito species in the Americas are also presented. Nineteen American countries are currently infested and few mainland American countries have not confirmed the occurrence of Ae. albopictus. The large distribution and high frequency of Ae. albopictus in the Americas may become a critical factor in the spread of arboviruses like chikungunya in the new world.
Assuntos
Animais , Aedes , Distribuição Animal , Insetos Vetores , Controle de Mosquitos/normas , América , Aedes/classificação , Brasil , Cidades , Febre de Chikungunya/prevenção & controle , Dengue/prevenção & controle , Monitoramento Ambiental/normas , População UrbanaRESUMO
Distribution, abundance, feeding behaviour, host preference, parity status and human-biting and infection rates are among the medical entomological parameters evaluated when determining the vector capacity of mosquito species. To evaluate these parameters, mosquitoes must be collected using an appropriate method. Malaria is primarily transmitted by anthropophilic and synanthropic anophelines. Thus, collection methods must result in the identification of the anthropophilic species and efficiently evaluate the parameters involved in malaria transmission dynamics. Consequently, human landing catches would be the most appropriate method if not for their inherent risk. The choice of alternative anopheline collection methods, such as traps, must consider their effectiveness in reproducing the efficiency of human attraction. Collection methods lure mosquitoes by using a mixture of olfactory, visual and thermal cues. Here, we reviewed, classified and compared the efficiency of anopheline collection methods, with an emphasis on Neotropical anthropophilic species, especially Anopheles darlingi, in distinct malaria epidemiological conditions in Brazil.
Assuntos
Animais , Humanos , Anopheles/classificação , Insetos Vetores/classificação , Controle de Mosquitos/instrumentação , Brasil , Malária/transmissão , Controle de Mosquitos/métodos , Estações do AnoRESUMO
Two hypotheses for how conditions for larval mosquitoes affect vectorial capacity make opposite predictions about the relationship of adult size and frequency of infection with vector-borne pathogens. Competition among larvae produces small adult females. The competition-susceptibility hypothesis postulates that small females are more susceptible to infection and predicts frequency of infection should decrease with size. The competition-longevity hypothesis postulates that small females have lower longevity and lower probability of becoming competent to transmit the pathogen and thus predicts frequency of infection should increase with size. We tested these hypotheses for Aedes aegypti in Rio de Janeiro, Brazil, during a dengue outbreak. In the laboratory, longevity increases with size, then decreases at the largest sizes. For field-collected females, generalised linear mixed model comparisons showed that a model with a linear increase of frequency of dengue with size produced the best Akaike’s information criterion with a correction for small sample sizes (AICc). Consensus prediction of three competing models indicated that frequency of infection increases monotonically with female size, consistent with the competition-longevity hypothesis. Site frequency of infection was not significantly related to site mean size of females. Thus, our data indicate that uncrowded, low competition conditions for larvae produce the females that are most likely to be important vectors of dengue. More generally, ecological conditions, particularly crowding and intraspecific competition among larvae, are likely to affect vector-borne pathogen transmission in nature, in this case via effects on longevity of resulting adults. Heterogeneity among individual vectors in likelihood of infection is a generally important outcome of ecological conditions impacting vectors as larvae.
Assuntos
Animais , Feminino , Aedes/crescimento & desenvolvimento , Tamanho Corporal/fisiologia , Dengue/transmissão , Epidemias , Insetos Vetores/crescimento & desenvolvimento , Aedes/anatomia & histologia , Aedes/virologia , Teorema de Bayes , Brasil/epidemiologia , Aglomeração , Comportamento Competitivo/fisiologia , Vírus da Dengue/isolamento & purificação , Dengue/epidemiologia , Monitoramento Ambiental , Insetos Vetores/virologia , Larva/anatomia & histologia , Larva/crescimento & desenvolvimento , Longevidade/fisiologia , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Brazil, a country of continental proportions, presents three profiles of malaria transmission. The first and most important numerically, occurs inside the Amazon. The Amazon accounts for approximately 60% of the nation’s territory and approximately 13% of the Brazilian population. This region hosts 99.5% of the nation’s malaria cases, which are predominantly caused by Plasmodium vivax (i.e., 82% of cases in 2013). The second involves imported malaria, which corresponds to malaria cases acquired outside the region where the individuals live or the diagnosis was made. These cases are imported from endemic regions of Brazil (i.e., the Amazon) or from other countries in South and Central America, Africa and Asia. Imported malaria comprised 89% of the cases found outside the area of active transmission in Brazil in 2013. These cases highlight an important question with respect to both therapeutic and epidemiological issues because patients, especially those with falciparum malaria, arriving in a region where the health professionals may not have experience with the clinical manifestations of malaria and its diagnosis could suffer dramatic consequences associated with a potential delay in treatment. Additionally, because the Anopheles vectors exist in most of the country, even a single case of malaria, if not diagnosed and treated immediately, may result in introduced cases, causing outbreaks and even introducing or reintroducing the disease to a non-endemic, receptive region. Cases introduced outside the Amazon usually occur in areas in which malaria was formerly endemic and are transmitted by competent vectors belonging to the subgenus Nyssorhynchus (i.e., Anopheles darlingi, Anopheles aquasalis and species of the Albitarsis complex). The third type of transmission accounts for only 0.05% of all cases and is caused by autochthonous malaria in the Atlantic Forest, located primarily along the southeastern Atlantic Coast. They are caused by parasites that seem to be (or to be very close to) P. vivax and, in a less extent, by Plasmodium malariae and it is transmitted by the bromeliad mosquito Anopheles (Kerteszia) cruzii. This paper deals mainly with the two profiles of malaria found outside the Amazon: the imported and ensuing introduced cases and the autochthonous cases. We also provide an update regarding the situation in Brazil and the Brazilian endemic Amazon.
Assuntos
Animais , Humanos , Anopheles/classificação , Doenças Endêmicas , Insetos Vetores/classificação , Malária Falciparum/epidemiologia , Malária Vivax/epidemiologia , Viagem , Brasil/epidemiologia , Geografia Médica , Malária Falciparum/transmissão , Malária Vivax/transmissãoRESUMO
Wyeomyia exallos, a new mosquito species from Atlantic Forest of southeastern Brazil, is described based on morphological characters of the adult female, male, male genitalia, pupa and fourth-instar larva. The morphological characters of Wy. exallos sp. nov. are compared with those of different subgenera of Wyeomyia as well as of species without subgeneric position. It is proposed that the new species should be placed in genus Wyeomyia Theobald without subgeneric assignment.
Assuntos
Animais , Feminino , Masculino , Culicidae/anatomia & histologia , Culicidae/classificação , Brasil , Genitália Masculina/anatomia & histologia , Larva/anatomia & histologia , Pupa/anatomia & histologiaRESUMO
In this opinion paper, we discuss the potential and challenges of using the symbiont Wolbachia to block mosquito transmitted diseases such as dengue, malaria and chikungunya in Latin America.
Assuntos
Animais , Humanos , Culicidae/microbiologia , Insetos Vetores/microbiologia , Controle Biológico de Vetores/métodos , Wolbachia/fisiologia , Infecções por Alphavirus/prevenção & controle , Dengue/prevenção & controle , América Latina , Malária/prevenção & controleRESUMO
In Niterói, state of Rio de Janeiro, dengue virus type 4 (DENV-4) was isolated for the first time in March 2011. We analysed the laboratory findings of the first cases and evaluated the use of molecular techniques for the detection of DENV-4 in Aedes aegypti that were field-caught. Conventional reverse transcriptase-polymerase chain reaction (RT-PCR) and SimplexaTM Dengue real-time RT-PCR confirmed DENV-4 infection in all cases. Additionally, DENV-4 was confirmed in a female Ae. aegypti with 1.08 x 10³ copies/mL of virus, as determined by quantitative real-time RT-PCR. This is the first time the SimplexaTM Dengue real-time assay has been used for the classification of cases of infection and for entomological investigations. The use of these molecular techniques was shown to be important for the surveillance of dengue in humans and vectors.
Assuntos
Animais , Feminino , Humanos , Masculino , Aedes/virologia , Vírus da Dengue/genética , Dengue/virologia , Insetos Vetores/virologia , Brasil , Vírus da Dengue/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Anopheles triannulatus s.l. is a malaria vector with a wide geographic distribution, ranging from Argentina-Nicaragua and Trinidad. Here we analysed sequences of two genes, timeless and cpr, to assess the genetic variability and divergence among three sympatric cryptic species of this complex from Salobra, central-western Brazil. The timeless gene sequences did not conclusively differentiate Anopheles halophylus and An. triannulatus species "C". However, a partial separation has been observed between these species and An. triannulatus s.s. Importantly, the analysis of the cpr gene sequences revealed fixed differences, no shared polymorphisms and considerable genetic differentiation among the three species of the An. triannulatus complex. The results confirm that An. triannulatus s.s., An. halophylus and An. triannulatus species C are distinct taxa, with the latter two likely representing a more recent speciation event.
Assuntos
Animais , Feminino , Anopheles , Genes de Insetos , Variação Genética , Insetos Vetores , Análise de Sequência de DNA , Anopheles , Insetos Vetores , Reação em Cadeia da Polimerase , Especificidade da EspécieRESUMO
Recently, we showed that infection with dengue virus increases the locomotor activity of Aedes aegypti females. We speculate that the observed increased locomotor activity could potentially increase the chances of finding a suitable host and, as a consequence, the relative biting rate of infected mosquitoes. We used a mathematical model to investigate the impact of the increased locomotor activity by assuming that this activity translated into an increased biting rate for infected mosquitoes. The results show that the increased biting rate resulted in dengue outbreaks with greater numbers of primary and secondary infections and with more severe biennial epidemics.
Assuntos
Animais , Feminino , Humanos , Aedes/virologia , Vírus da Dengue/fisiologia , Dengue/transmissão , Insetos Vetores/virologia , Dengue/virologia , Modelos Biológicos , Dinâmica PopulacionalRESUMO
OBJECTIVE: To evaluate dispersal of Aedes aegypti females in an area with no container manipulation and no geographic barriers to constrain mosquito flight. METHODS: A mark-release-recapture experiment was conducted in December 2006, in the dengue endemic urban district of Olaria in Rio de Janeiro, Southeastern Brazil, where there is no evident obstacle to the dispersal of Ae. aegypti females. Mosquito traps were installed in 192 houses (96 Adultraps and 96 MosquiTRAPs). RESULTS: A total of 725 dust-marked gravid females were released and recapture rate was 6.3 percent. Ae. aegypti females traveled a mean distance of 288.12 m and their maximum displacement was 690 m; 50 percent and 90 percent of females flew up to 350 m and 500.2 m, respectively. CONCLUSIONS: Dispersal of Ae. aegypti females in Olaria was higher than in areas with physical and geographical barriers. There was no evidence of a preferred direction during mosquito flight, which was considered random or uniform from the release point.
OBJETIVO: Avaliar a dispersão de fêmeas de Aedes aegypti em uma área onde não houve nenhuma interferência quanto à redução de potenciais criadouros e não há barreira geográfica que limite o vôo dos mosquitos. MÉTODOS: Um experimento de marcação-soltura-recaptura foi realizado em dezembro de 2006, no bairro urbano Olaria, endêmico para dengue na cidade do Rio de Janeiro (RJ), onde não há obstáculos evidentes à dispersão de fêmeas de Ae. aegypti. Armadilhas para captura de mosquitos foram instaladas em 192 residências (96 Adultraps e 96 MosquiTraps). RESULTADOS: Foram soltas 725 fêmeas grávidas marcadas com pó fluorescente e a taxa de recaptura foi de 6,3 por cento. Fêmeas de Ae. aegypti dispersaram em média 288,12 m do ponto de soltura e o deslocamento máximo foi de 690 m; 50 por cento e 90 por cento das fêmeas voaram até 350 m e 500,2 m respectivamente. CONCLUSÕES: A dispersão de fêmeas de Ae. aegypti em Olaria foi maior que em áreas com barreiras físicas e/ou geográficas. Não houve evidências de preferência de direção do vôo dos mosquitos, o qual foi considerado randômico ou uniforme a partir do ponto de soltura.
OBJETIVO: Evaluar la dispersión de hembras de Aedes aegypti en un área sin manipulación de recipientes y sin barreras geográficas que limiten el vuelo del mosquito. MÉTODOS: Se realizó un experimento de marcaje y recaptura en diciembre de 2006, en el distrito urbano Olaria, Rio de Janeiro (Sureste de Brasil), área endémica para dengue, donde no hay obstáculo evidente para la dispersión de hembras de Ae. aegypti. Trampas para mosquitos fueron instaladas en 192 casas (96 Adultraps y 96 MosquiTraps). RESULTADOS: Un total de 725 hembras grávidas marcadas con polvo fueron liberadas y recapturadas siendo la tasa de 6,3 por ciento. Las hembras de Ae. Aegypti viajaron una distancia promedio de 288,12 m y su máximo desplazamiento fue de 690 m; 50 por ciento y 90 por ciento de las hembras volaron hasta los 350 m y 500,2 m, respectivamente. CONCLUSIONES: Dispersión de las hembras de Ae. aegypti en Olaria fue mayor que en las áreas con barreras físicas y geográficas. No hube evidencia de una dirección preferida durante el vuelo del mosquito, por lo que se considera aleatorio y uniforme desde el punto de liberación.
Assuntos
Animais , Feminino , Aedes/fisiologia , Voo Animal/fisiologia , Insetos Vetores/fisiologia , Brasil , Cidades , Corantes Fluorescentes , Controle de Mosquitos/instrumentação , Densidade Demográfica , População UrbanaRESUMO
Different urban structures might affect the life history parameters of Aedes aegypti and, consequently, dengue transmission. Container productivity, probability of daily survival (PDS) and dispersal rates were estimated for mosquito populations in a high income neighbourhood of Rio de Janeiro. Results were contrasted with those previously found in a suburban district, as well as those recorded in a slum. After inspecting 1,041 premises, domestic drains and discarded plastic pots were identified as the most productive containers, collectively holding up to 80 percent of the total pupae. In addition, three cohorts of dust-marked Ae. aegypti females were released and recaptured daily using BGS-Traps, sticky ovitraps and backpack aspirators in 50 randomly selected houses; recapture rate ranged from 5-12.2 percent within cohorts. PDS was determined by two models and ranged from 0.607-0.704 (exponential model) and 0.659-0.721 (non-linear model), respectively. Mean distance travelled varied from 57-122 m, with a maximum dispersal of 263 m. Overall, lower infestation indexes and adult female survival were observed in the high income neighbourhood, suggesting a lower dengue transmission risk in comparison to the suburban area and the slum. Since results show that urban structure can influence mosquito biology, specific control strategies might be used in order to achieve cost-effective Ae. aegypti control.
Assuntos
Animais , Feminino , Aedes/fisiologia , Insetos Vetores/fisiologia , Longevidade , Brasil , Dengue/transmissão , Dinâmica Populacional , Estações do Ano , População UrbanaRESUMO
Population size and daily survival rates of disease vectors are important determinants of vectorial capacity. A mark-release-recapture experiment was conducted in a dengue endemic urban neighborhood of Rio de Janeiro, Brazil, to estimate population size, survival rate and vectorial capacity of Aedes aegypti females using back-pack aspirators and gravid sticky traps (MosquiTRAP). Estimations of the gravid female population size were different when using data gathered from just the MosquiTRAP (3,505 individuals) or aspirator (1,470). However Ae. aegypti survival rates and longevity were similar irrespective of the method of capture. Up to 26.3 percent of released females would be able to survive for more than 10 days, the length of time of the extrinsic incubation period. Vectorial capacity value ranged between 0.01567 and 0.4215 and the basic reproductive number (R0) was estimated to be between 0.0695 and 1.88.
O tamanho populacional e a taxa de sobrevivência de vetores de doenças são importantes componentes da capacidade vetorial. Um experimento de marcação-soltura-recaptura foi conduzido numa área urbana endêmica de dengue no Rio de Janeiro, Brasil, para estimar o tamanho populacional, taxa de sobrevivência diária e capacidade vetorial de fêmeas de Aedes aegypti; para tal, usaram-se aspirador costal e armadilha para fêmeas grávidas de Ae. aegypti (MosquiTRAP). Estimativas do tamanho populacional de fêmeas grávidas foram diferentes quando foram analisados dados coletados apenas na MosquiTRAP (3.505 indivíduos) e aspiradores (1.470). Por outro lado, taxas de sobrevivência e longevidade de Ae. aegypti foram semelhantes independentemente do método de captura empregado. Até 26,3 por cento das fêmeas seriam capazes de sobreviver mais do que dez dias, tempo equivalente à duração do período de incubação extrínseco. O cálculo da capacidade vetorial revelou valores entre 0,01567 e 0,4215, e o número básico de reprodução foi estimado entre 0,0695 e 1,88.