Bionomia de Culex quinquefasciatus em áreas urbanas no Rio de Janeiro, RJ

OBJECTIVE: To evaluate density, parity rates, daily survival and longevity of natural populations of Culex quinquefasciatus in three neighborhoods with distinct socio-economic and infrastructure profiles. METHODS: Mosquito collections of the Culex quinquefasciatus species were performed weekly during two four month periods, from August to November 2008 (spring) and March to June 2009 (fall), in a favela (slum), a suburban area and a middle class area of Rio de Janeiro, Southeastern Brazil. Collections were performed with backpack aspirators, in 20 randomly selected houses in each area per week, during 15-20 minutes per house. Ovaries were removed from captured females and classified as initial, intermediary or final stage. Furthermore, females were dissected for determination of parity based on the condition of the tracheal system. Mosquito survival rate and longevity were estimated on a per month basis for each neighborhood. RESULTS: We collected a total of 2,062 Culex quinquefasciatus, but monthly vector density was not correlated with temperature and rainfall. We dissected the ovaries of 625 Culex quinquefasciatus, and overall, there was a higher proportion of nulliparous females during the dryer months, while gravid females were more frequent in rainy months. In the middle class neighborhood, the parity rate reached up to 93.75% with survivorship of 0.979. Lower parity and survival rates were obtained in the suburban area (as low as 36.4% parity and 0.711 daily survival). Up to 84.7% of Culex quinquefasciatus females could survive the eight day period needed to complete West Nile Virus incubation. CONCLUSIONS: The survival rate of Culex quinquefasciatus varied significantly between the neighborhoods. This suggests that vectorial capacity and disease transmission risk may vary greatly between different urban areas, which is potentially useful information for vector control programs.OBJETIVO: Evaluar densidad, tasa de paridad, sobrevivencia diaria y longevidad de poblaciones naturales de Culex quinquefasciatus de tres localidades con diferentes perfiles socioeconómicos y de infraestructura. MÉTODOS: Mosquitos de la especie Culex quinquefasciatus fueron colectados semanalmente en dos períodos de cuatro meses, de agosto a noviembre de 2008 y de marzo a junio de 2009, en un barrio, un área de suburbio y una urbanización de clase media en Rio de Janeiro, Litoral Sudeste de Brasil. Las colectas se realizaron con ayuda de aspiradores costales en 20 domicilios, aleatoriamente seleccionados por semana y por área, durante 15-20 minutos por domicilio. A las hembras capturadas se les retiraron los ovarios y clasificaron en fases inicial, intermediario y final. Adicionalmente, las hembras fueron diseccionadas para determinar la paridad de acuerdo con las condiciones del sistema traqueal. La tasa de sobrevivencia y la longevidad de las hembras fueron estimadas por mes para cada localidad. RESULTADOS: Se colectaron 2.062 Culex quinquefasciatus, sin embargo, la densidad mensual del vector no presentó correlación con la temperatura y precipitación. Se diseccionaron los ovarios de 625 Culex quinquefasciatus y se obtuvo mayor proporción de hembras nulíparas durante los meses más secos, mientras que las hembras grávidas fueron más frecuentes en los meses de lluvia. La tasa de paridad alcanzó el 93,75% en la urbanización de clase media, con sobrevivencia de 0,979. Menores valores de paridad y sobrevivencia se obtuvieron en el suburbio (comenzando en 36,4% de paridad y 0,711 de sobrevivencia diaria). El 84,7% de las hembras de Culex quinquefasciatus podrían sobrevivir al período de ocho días, necesario para completar el período de incubación del virus de la fiebre del Oeste del Nilo. CONCLUSIONES: La tasa de sobrevivencia de Culex quinquefasciatus varió significativamente entre las urbanizaciones, sugiriendo que la capacidad vectorial y el riesgo de transmisión de enfermedades pueden variar entre diferentes áreas urbanas, información relevante para la planificación de los programas de control de vectores.OBJETIVO: Avaliar densidade, taxa de paridade, sobrevivência diária e longevidade de populações naturais de Culex quinquefasciatus de três localidades com diferentes perfis socioeconômicos e de infraestrutura. MÉTODOS: Mosquitos da espécie Culex quinquefasciatus foram coletados semanalmente em dois períodos de quatro meses, de agosto a novembro de 2008 e de março a junho de 2009, em uma comunidade, uma área de subúrbio e um bairro de classe média no Rio de Janeiro, RJ. As coletas foram realizadas com o auxílio de aspiradores costais em 20 domicílios, aleatoriamente selecionados por semana e por área, durante 15-20 minutos por domicílio. As fêmeas capturadas tiveram os ovários removidos e classificados em estágios inicial, intermediário e final. Adicionalmente, as fêmeas foram dissecadas para determinação da paridade de acordo com as condições do sistema traqueal. A taxa de sobrevivência e a longevidade das fêmeas foram estimadas por mês, para cada localidade. RESULTADOS: Foram coletados 2.062 Culex quinquefasciatus, porém a densidade mensal deste vetor não apresentou correlação com temperatura e precipitação. Dissecamos os ovários de 625 Culex quinquefasciatus e obtivemos maior proporção de fêmeas nulíparas durante os meses mais secos, enquanto fêmeas grávidas foram mais frequentes nos meses chuvosos. A taxa de paridade foi de até 93,75% no bairro de classe média, com sobrevivência de 0,979. Menores valores de paridade e sobrevivência foram obtidos no subúrbio (começando em 36,4% de paridade e 0,711 de sobrevivência diária). Até 84,7% das fêmeas de Culex quinquefasciatus poderiam sobreviver ao período de oito dias, necessário para completar o período de incubação do vírus da febre do Nilo Ocidental. CONCLUSÕES: A taxa de sobrevivência de Culex quinquefasciatus variou significativamente entre os bairros, o que sugere que a capacidade vetorial e o risco de transmissão de doenças podem variar entre diferentes áreas urbanas, informação relevante para o planejamento dos programas de controle de vetores

Bionomics of Culex quinquefasciatus within urban areas of Rio de Janeiro, Southeastern Brazil

OBJECTIVE: To evaluate density, parity rates, daily survival and longevity of natural populations of Culex quinquefasciatus in three neighborhoods with distinct socio-economic and infrastructure profiles. METHODS: Mosquito collections of the Culex quinquefasciatus species were performed weekly during two four month periods, from August to November 2008 (spring) and March to June 2009 (fall), in a favela (slum), a suburban area and a middle class area of Rio de Janeiro, Southeastern Brazil. Collections were performed with backpack aspirators, in 20 randomly selected houses in each area per week, during 15-20 minutes per house. Ovaries were removed from captured females and classified as initial, intermediary or final stage. Furthermore, females were dissected for determination of parity based on the condition of the tracheal system. Mosquito survival rate and longevity were estimated on a per month basis for each neighborhood. RESULTS: We collected a total of 2,062 Culex quinquefasciatus, but monthly vector density was not correlated with temperature and rainfall. We dissected the ovaries of 625 Culex quinquefasciatus, and overall, there was a higher proportion of nulliparous females during the dryer months, while gravid females were more frequent in rainy months. In the middle class neighborhood, the parity rate reached up to 93.75% with survivorship of 0.979. Lower parity and survival rates were obtained in the suburban area (as low as 36.4% parity and 0.711 daily survival). Up to 84.7% of Culex quinquefasciatus females could survive the eight day period needed to complete West Nile Virus incubation. CONCLUSIONS: The survival rate of Culex quinquefasciatus varied significantly between the neighborhoods. This suggests that vectorial capacity and disease transmission risk may vary greatly between different urban areas, which is potentially useful information for vector control programs

Impacto da infecção com o vírus dengue 2 no comportamento alimentar, longevidade e fecundidade de fêmeas de Aedes aegypti

Submitted by Alessandra Portugal ([email protected]) on 2013-09-17T12:41:29Z No. of bitstreams: 1 Dissertacao de Mestrado - Gabriel Sylvestre Ribeiro.pdf: 1533452 bytes, checksum: 8d2db7800d46ef716ec2f56b355c2d8e (MD5)Made available in DSpace on 2013-09-17T12:41:29Z (GMT). No. of bitstreams: 1 Dissertacao de Mestrado - Gabriel Sylvestre Ribeiro.pdf: 1533452 bytes, checksum: 8d2db7800d46ef716ec2f56b355c2d8e (MD5) Previous issue date: 2012-03-23Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, BrasilO vírus da dengue é transmitido nas Américas por mosquitos Aedes aegypti. Este é adquirido através da picada em um hospedeiro em viremia e passa por intensa replicação em diferentes tecidos do inseto até tornar-se transmissível, após as partículas virais atingirem a luz das glândulas salivares. A partir deste momento o vírus pode ser inoculado, juntamente com a saliva, em todos os hospedeiros suscetíveis nos quais a fêmea se alimentar. Supõe-se que o vírus da dengue gere efeitos negativos sobre a biologia do mosquito, diminuindo o fitness dos indivíduos infectados. Apesar dos avanços recentes no conhecimento acerca de sua capacidade vetorial, ainda existem muitas lacunas na interação mosquito-vírus no par Ae. aegypti/dengue. Desta maneira, nosso objetivo é avaliar o impacto da infecção por DENV-2 no hábito alimentar do mosquito Ae. aegypti e, adicionalmente, monitorar a sobrevivência, longevidade, sucesso de oviposição e fecundidade de insetos infectados e controles. Duas populações foram testadas: Paea, confinada em laboratório desde 1994, e uma população de campo, coletada com o uso de ovitrampas em Tubiacanga (RJ). Fêmeas das duas populações foram aleatoriamente selecionadas para receber sangue infectado com 2x10-8 partículas de DENV-2 ou sangue com sobrenadante de cultura de célula livre de vírus, constituindo o grupo controle. Após a infecção oral, as fêmeas que estavam visualmente ingurgitadas foram confinadas individualmente em tubos de plástico. Ao longo de cinco semanas monitoramos aspectos de sua biologia e capacidade vetorial, tais como sua sobrevivência, fecundidade e cinco parâmetros do comportamento alimentar: tempo de início, o tempo gasto na localização do hospedeiro (camundongo anestesiado); o número de provas, quantas vezes a fêmea insere e retira sua probóscide do corpo do hospedeiro; tempo de prova, que termina quando notamos a inflação abdômen; o tempo de ingestão, que vai até a repleção total e retirada da probóscide do corpo do hospedeiro; tempo total de alimentação, a soma dos tempos de início, prova e ingestão. Utilizando uma análise de risco, fomos capazes de observar que a infecção pelo DENV-2 não modificou o hábito alimentar das fêmeas de Ae. aegypti. Por outro lado, a sobrevivência e a fecundidade foram menores quando a fêmea estava infectada com DENV-2. Através de uma ANOVA, observamos a influência da infecção na longevidade (F = 20,75 , gl = 1, P = 0,0001). A curva de sobrevivência das fêmeas infectadas apresentou queda significativamente mais intensa que a dos seus pares não-infectados (χ2 = 16,5, gl = 1, P < 0,001). Em relação à fecundidade, fêmeas infectadas têm menor sucesso de oviposição, ou seja, menor probabilidade de colocar ovos (χ2 = 14,40, gl = 3, p = 0,0024). Além disso, as fêmeas infectadas fazem a postura de um número significativamente menor de ovos do que seus pares não infectados.Dengue virus is transmitted in the Americas by Aedes aegypti mosquitoes. This virus is acquired from an infected host through the bite and undergoes intense replication in different tissues of the insect becoming transmissible only after the viral particles reach the lumen of salivary glands. From this moment on the virus can be inoculated with saliva into all susceptible hosts the female will eat. It is assumed that the dengue virus generates negative effects on the mosquito’s biology, decreasing the fitness of infected individuals. Despite recent advances in knowledge of the Ae. aegypti vectorial capacity, there are still many gaps in the knowledge of the interaction between Ae. aegypti / dengue. Thus, our goal is to evaluate the impact of infection with DENV-2 in the feeding habits of the mosquito Ae. aegypti and additionally monitor the survival, longevity, oviposition success and fecundity of infected and control insects. Two populations were tested: Paea, confined in the laboratory since 1994, and one from the field, collected using ovitraps in Tubiacanga (RJ). Females of both populations were randomly selected to receive blood infected with 2x10-8 particules of DENV-2 or blood culture supernatant from virus-free cells, constituting the control group. After oral infection, the visually engorged females were separated individually in plastic tubes. We have monitored, over five weeks, aspects of their biology and vectorial capacity, such as survival, fecundity and five parameters of their feeding behavior: start time, the time spent in locating the host (anesthetized mice); the number of probes, how many times the female inserts and takes off her proboscis; probing time, that ends when we notice the abdomen inflation; ingestion time, that goes until the total repletion and proboscis withdrawal from the mouse’s body; total feeding time, the sum of start, probing and ingestion times. Using a failure-time analysis, we were able to observe that infection with DENV-2 did not change the feeding habits of Ae. aegypti. Moreover, the survival and fecundity were lower when the female was infected with DENV-2. Using an ANOVA, we observed the influence of infection on longevity (F = 20.75, df = 1, P = 0.0001). The survivorship of infected females showed a significantly more intense mortality than that of their non-infected counterparts (χ2 = 16.5, df = 1, P <0.001). Regarding fecundity, infected females had a low oviposition success, i.e., they were less likely to lay eggs (χ2 = 14.40, df = 3, p = 0.0024). Moreover, the postures of infected females had significantly lower numbers of eggs than the ones from their uninfected peers

Bionomics of Culex quinquefasciatus within urban areas of Rio de Janeiro, Southeastern Brazil

OBJECTIVE: To evaluate density, parity rates, daily survival and longevity of natural populations of Culex quinquefasciatus in three neighborhoods with distinct socio-economic and infrastructure profiles. METHODS: Mosquito collections of the Culex quinquefasciatus species were performed weekly during two four month periods, from August to November 2008 (spring) and March to June 2009 (fall), in a favela (slum), a suburban area and a middle class area of Rio de Janeiro, Southeastern Brazil. Collections were performed with backpack aspirators, in 20 randomly selected houses in each area per week, during 15-20 minutes per house. Ovaries were removed from captured females and classified as initial, intermediary or final stage. Furthermore, females were dissected for determination of parity based on the condition of the tracheal system. Mosquito survival rate and longevity were estimated on a per month basis for each neighborhood. RESULTS: We collected a total of 2,062 Culex quinquefasciatus, but monthly vector density was not correlated with temperature and rainfall. We dissected the ovaries of 625 Culex quinquefasciatus, and overall, there was a higher proportion of nulliparous females during the dryer months, while gravid females were more frequent in rainy months. In the middle class neighborhood, the parity rate reached up to 93.75% with survivorship of 0.979. Lower parity and survival rates were obtained in the suburban area (as low as 36.4% parity and 0.711 daily survival). Up to 84.7% of Culex quinquefasciatus females could survive the eight day period needed to complete West Nile Virus incubation. CONCLUSIONS: The survival rate of Culex quinquefasciatus varied significantly between the neighborhoods. This suggests that vectorial capacity and disease transmission risk may vary greatly between different urban areas, which is potentially useful information for vector control programs

Bionomics of Culex quinquefasciatus within urban areas of Rio de Janeiro, Southeastern Brazil

OBJECTIVE: To evaluate density, parity rates, daily survival and longevity of natural populations of Culex quinquefasciatus in three neighborhoods with distinct socio-economic and infrastructure profiles. METHODS: Mosquito collections of the Culex quinquefasciatus species were performed weekly during two four month periods, from August to November 2008 (spring) and March to June 2009 (fall), in a favela (slum), a suburban area and a middle class area of Rio de Janeiro, Southeastern Brazil. Collections were performed with backpack aspirators, in 20 randomly selected houses in each area per week, during 15-20 minutes per house. Ovaries were removed from captured females and classified as initial, intermediary or final stage. Furthermore, females were dissected for determination of parity based on the condition of the tracheal system. Mosquito survival rate and longevity were estimated on a per month basis for each neighborhood. RESULTS: We collected a total of 2,062 Culex quinquefasciatus, but monthly vector density was not correlated with temperature and rainfall. We dissected the ovaries of 625 Culex quinquefasciatus, and overall, there was a higher proportion of nulliparous females during the dryer months, while gravid females were more frequent in rainy months. In the middle class neighborhood, the parity rate reached up to 93.75% with survivorship of 0.979. Lower parity and survival rates were obtained in the suburban area (as low as 36.4% parity and 0.711 daily survival). Up to 84.7% of Culex quinquefasciatus females could survive the eight day period needed to complete West Nile Virus incubation. CONCLUSIONS: The survival rate of Culex quinquefasciatus varied significantly between the neighborhoods. This suggests that vectorial capacity and disease transmission risk may vary greatly between different urban areas, which is potentially useful information for vector control programs

She’s a femme fatale: low-density larval development produces good disease vectors

Made available in DSpace on 2015-09-21T17:25:31Z (GMT). No. of bitstreams: 2 license.txt: 1914 bytes, checksum: 7d48279ffeed55da8dfe2f8e81f3b81f (MD5) gabriel_ribeiro_etal_IOC-2014.pdf: 532679 bytes, checksum: f215003bbb51ceecf78e0a3839f44645 (MD5) Previous issue date: 2014Illinois State University. School of Biological Science. Normal, IL, USA.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Transmissores de Hematozoários. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Transmissores de Hematozoários. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Transmissores de Hematozoários. Rio de Janeiro, RJ, Brasil.Programa de Computação Científica-Fiocruz. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Transmissores de Hematozoários. Rio de Janeiro, RJ, Brasil.University of Florida. Florida Medical Entomology Laboratory. Gainesville, FL, USA.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

She’s a femme fatale: low-density larval development produces good disease vectors

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&#8217;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

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora