52 research outputs found

    Estudos epidemiológicos da Mansonella ozzardi (Nematoda, Onchocercidae) em comunidades indígenas do município de Pauini, Amazonas, Brasil

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    The Mansonella ozzardi has a widespread distribution among the indigenous and riverine communities of Amazonas, Brazil. We estimated the prevalence of Mansonella ozzardi in indigenous communities of the Pauini municipality, Amazonas state, Brazil and the rate of parasitic infection in vectors. We collected thick blood smears from individuals from six Apurin√£ indigenous communities along the Purus River and its tributaries. Collections of simuliids were made and dissected, and the larval instars of M. ozzardi identified. The overall prevalence of M. ozzardi was 28.40%, with the highest incidence among males and agricultural workers. Among age groups, children 2-9 years of age had the lowest incidence, while individuals older than 58 exhibited the highest rates of infection. We found infected simuliids in three communities, with Parasitic Infection Rates (PIR) of 0.34-6.58%. The prevalence of M. ozzardi among the Apurin√£ people is high, possibly related to the diary activities of the riparian people, where a high abundance of the vectors exists.Esse trabalho tem como objetivos estimar a preval√™ncia de Mansonella ozzardi em comunidades ind√≠genas do munic√≠pio de Pauini, Amazonas, Brasil e estimar a Taxa de Infec√ß√£o Parasit√°ria nos vetores. Foram examinados ind√≠genas da etnia Apurin√£, pelo m√©todo de gota espessa, em seis comunidades localizadas as margens e afluentes do rio Purus. A preval√™ncia geral para M. ozzardi foi de 28,40%, com maior incid√™ncia para o sexo masculino e nos indiv√≠duos com atividade no campo (agricultores). Em rela√ß√£o √† faixa et√°ria, as menores preval√™ncias foram obtidas nos indiv√≠duos mais jovens (2-9 anos), enquanto as maiores nos indiv√≠duos acima de 58 anos. Foram encontrados simul√≠deos parasitados em tr√™s comunidades, com uma Taxa de Infec√ß√£o Parasit√°ria que variou de 0,34 a 6,58%. A preval√™ncia de M. ozzardi entre os Apurin√£ √© elevada, possivelmente relacionada √†s suas atividades di√°rias as margens dos rios, onde existe uma grande abund√Ęncia dos vetores

    Description of two new species of Palpomyia Meigen (Diptera: Ceratopogonidae) from the Brazilian Amazon

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    Resumo. Duas novas esp√©cies de insetos predadores e bioindicadores da qualidade da √°gua do g√™nero Palpomyia, grupo distincta, s√£o descritas e ilustradas baseadas em esp√©cimes machos. Os imaturos das esp√©cies Palpomyia amazonensis sp. nov. e Palpomyia lanceolata sp. nov. foram coletados em armadilhas ovitrampas e criados em laborat√≥rio at√© adultos. Ambas novas esp√©cies s√£o semelhantes a Palpomyia guyana Clastrier, 1992 e Palpomyia turnbowi Grogan et al., 2013 e diferem de Palpomyia versicolor Macfie, 1939, √ļnica esp√©cie do grupo distincta descrita na Amaz√īnia Brasileira. Com as duas descri√ß√Ķes, foram aumentadas para tr√™s o n√ļmero de esp√©cies para a Amaz√īnia e 32 para o Brasil. Descri√ß√£o de duas novas esp√©cies de Palpomyia Meigen (Diptera: Ceratopogonidae) da Amaz√īnia brasileira Abstract. Two new Amazonian predaceous midge of the genus Palpomyia, from the distincta group, were described based on male specimens. This genus is an important bioindicator of aquatic environments. The immatures of Palpomyia amazonensis sp. nov. and Palpomyia lanceolata sp. nov. were collected with ovitraps and reared in laboratory until adulthood. Both new species are similar with Palpomyia guyana Clastrier, 1992 and Palpomyia turnbowi Grogan et al., 2013 but differs from Palpomyia versicolor Macfie, 1939, the unique species described in Brazilian Amazon until now. With the description of these new species we increase to three the representative species of the distincta group in the Brazilian Amazon and to 32 the number of Brazilian species of Palpomyia

    Hematophagous biting midges (Diptera: Ceratopogonidae) from Tefé municipality, Amazonas state, Brazil

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    Some species of biting midges are vectors of pathogens that cause disease in vertebrates, including humans. The aim of this study was to survey the biting midge fauna in Tefé, Amazonas, Brazil. Culicoides were collected using HP light traps during January, February, and April 2013. Midges collected included one species from the genus Lectoconops that bites humans. A total of 248 Culicoides individuals were collected, representing 19 species from two subgenera (Haematomyidium and Hoffmania) and four informal species groups (carpenteri, leoni, fluvialis, and reticulatus). Twelve individuals of L. brasiliensis were also collected, and this is the first record of L. brasiliensis in Amazonas. Three species of Culicoides were also recorded for the first time in Amazonas, including Culicoides aitkeni, C. glabellus and C. ocumarensis. The most abundant species were C. hylas (81 individuals), and C. foxi (27). The Culicoides fauna in Tefé is diverse, and proven vectors such as C. paraensis and C. insignis were found

    Diversity of biting midges Culicoides (Diptera: Ceratopogonidae), potential vectors of disease, in different environments in an Amazonian rural settlement, Brazil

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    The Culicoides transmit a variety of pathogens. Our aim was to survey the Culicoides species occurring in an Amazonian rural settlement, comparing abundance, richness, and diversity in different environments. METHODS: Culicoides were captured using CDC light traps. The Shannon-Wiener (H') and Rényi indices were used to compare species diversity and evenness between environments, the equitability (J') index was used to calculate the uniformity of distribution among species, and similarity was estimated using the Jaccard similarity index. A permutational multivariate analysis of variance was applied to assess the influence of environment on species composition. A non-metric dimensional scale was used to represent the diversity profiles of each environment in a multidimensional space. RESULTS: 6.078 Culicoides were captured, representing 84 species (45 valid species/39 morphotypes). H' values showed the following gradient: forest > capoeira > peridomicile > forest edge. The equitability J' was greater in capoeira and forests compared to peridomiciles and the forest edge. The population compositions of each environment differed statistically, but rarefaction estimates indicate that environments of the same type possessed similar levels of richness. Species of medical and veterinary importance were found primarily in peridomiciles: C. paraensis, vector of Oropouche virus; C. insignis and C. pusillus, vectors of Bluetongue virus; C. filariferus, C. flavivenula, C. foxi, and C. ignacioi, found carrying Leishmania DNA. CONCLUSIONS: This study indicates that diversity was higher in natural environments than in anthropized environments, while abundance and richness were highest in the most anthropized environment. These findings suggest that strictly wild Culicoides can adapt to anthropized environments

    Local hydrological conditions influence tree diversity and composition across the Amazon basin

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    Tree diversity and composition in Amazonia are known to be strongly determined by the water supplied by precipitation. Nevertheless, within the same climatic regime, water availability is modulated by local topography and soil characteristics (hereafter referred to as local hydrological conditions), varying from saturated and poorly drained to well-drained and potentially dry areas. While these conditions may be expected to influence species distribution, the impacts of local hydrological conditions on tree diversity and composition remain poorly understood at the whole Amazon basin scale. Using a dataset of 443 1-ha non-flooded forest plots distributed across the basin, we investigate how local hydrological conditions influence 1) tree alpha diversity, 2) the community-weighted wood density mean (CWM-wd) ‚Äď a proxy for hydraulic resistance and 3) tree species composition. We find that the effect of local hydrological conditions on tree diversity depends on climate, being more evident in wetter forests, where diversity increases towards locations with well-drained soils. CWM-wd increased towards better drained soils in Southern and Western Amazonia. Tree species composition changed along local soil hydrological gradients in Central-Eastern, Western and Southern Amazonia, and those changes were correlated with changes in the mean wood density of plots. Our results suggest that local hydrological gradients filter species, influencing the diversity and composition of Amazonian forests. Overall, this study shows that the effect of local hydrological conditions is pervasive, extending over wide Amazonian regions, and reinforces the importance of accounting for local topography and hydrology to better understand the likely response and resilience of forests to increased frequency of extreme climate events and rising temperatures

    Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

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    Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ‚Č•‚ÄČ9.55‚ÄČcm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

    Estimating the global conservation status of more than 15,000 Amazonian tree species

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    Pervasive gaps in Amazonian ecological research

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    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5‚Äď7 vast areas of the tropics remain understudied.8‚Äď11 In the American tropics, Amazonia stands out as the world‚Äôs most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13‚Äď15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon‚Äôs biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region‚Äôs vulnerability to environmental change. 15%‚Äď18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
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