Distribución espacial de Anopheles pseudopunctipennis en las Yungas de Salta, Argentina

OBJETIVO: Comparar la abundancia de Anopheles pseudopunctipennis, y otros anofelinos, en tres zonas silvestres y modificadas por el hombre, a fin de verificar en qué medida tales diferencias ambientales afectan la distribución espacial de estos mosquitos. MÉTODOS: Se realizaron muestreos mensuales (diciembre de 2001 a diciembre de 2002), con trampas de luz CDC con CO2, en cada sitio de muestreo (selva, borde de selva y peridomicilio). En el peridomicilio, además, dos operadores aspiraron mosquitos posados sobre las paredes. Se estimaron índices de diversidad y abundancia de especies, y se intentó caracterizar a los ambientes estudiados mediante ANOVA, cálculo de cosenos y análisis de agrupamientos. RESULTADOS: Anopheles pseudopunctipennis fue la especie más abundante. Se colectaron también An. argyritarsis, An. nuneztovari, An. rangeli y An. strodei. Excepto An. nuneztovari que no se capturó en el peridomicilio, las demás se colectaron en los tres ambientes. No hubo diferencias en los índices de diversidad, ni tampoco entre los ambientes estudiados; sin embargo, el análisis de agrupamiento separó el borde de la selva, donde todas las especies fueron más abundantes en general. CONCLUSIONES: El borde de la selva fue el ambiente que presentó la mayor abundancia, representando, además del peridomicilio, un ambiente de alto riesgo para la transmisión del paludismo.

Vetores de malária em duas reservas indígenas da Amazônia Brasileira

OBJETIVO: Descrever a composição, características ecológicas e comportamentais e infectividade das espécies de anofelinos em reservas indígenas da região Amazônica. MÉTODOS: O estudo foi conduzido no ano de 2002 em aldeias das reservas indígenas Nhamundá-Mapuera e Cuminapanema no estado do Pará. Foram realizadas três coletas de duas semanas em cada reserva, com capturas de adultos e de imaturos. Anofelinos adultos foram capturados com capturador de Castro por atração humana nos ambientes intra e peridomiciliares, no período das 18h às 21h e das 18 às 06h e avaliados para verificação da paridade e infectividade para plasmódios por dissecção e ELISA. As coleções hídricas próximas às aldeias foram pesquisadas utilizando conchas de 500 ml, sendo 20 conchadas a cada 10 m, cobrindo-se a extensão máxima de 200 m de perímetro do criadouro. RESULTADOS: Foram capturadas 8.668 fêmeas somando-se as coletas das duas reservas. Anopheles darlingi foi a espécie predominante, com maior freqüência no peridomicílio. Na reserva Mapuera, a atividade hematofágica concentrou-se entre as 20h e 24h e, em Cuminapanema, manteve-se elevada até as 24h, diminuindo após esse horário e voltando a elevar-se no início da manhã. Das 6.350 fêmeas de An. darlingi examinadas, 18 estavam infectadas por Plasmodium vivax VK 247, VK 210, P. falciparum e P. malariae. Outras 1.450 fêmeas de outras espécies foram examinadas, mas nenhuma foi encontrada infectada. An. nuneztovari e Chagasia bonnae foram as espécies mais freqüentes nos criadouros das aldeias Mapuera e Cuminapanema, respectivamente. Imaturos de An. darlingi não foram localizados em Mapuera e foram capturados em apenas uma das coletas da reserva Cuminapanema. CONCLUSÕES: As populações de An. darlingi das duas reservas apresentaram comportamento exofílico e intensa atividade noturna. A ocorrência de imaturos foi pouco freqüente e a densidade larvária foi baixa. As características comportamentais dos vetores não se mostraram favoráveis às atividades usuais de controle vetorial.

Malaria vectors in the Brazilian Amazon: Anopheles of the subgenus Nyssorhynchus

Various species of Anopheles (Nyssorhynchus) were studied in the Amazon with the objective of determining their importance as malaria vectors. Of the 33 known Anopheles species occurring in the Amazon, only 9 were found to be infected with Plasmodium. The different species of this subgenus varied both in diversity and density in the collection areas. The populations showed a tendency towards lower density and diversity in virgin forest than in areas modified by human intervention. The principal vector, An. darlingi, is anthropophilic with a continuous activity cycle lasting the entire night but peaking at sunset and sunrise. These species (Nyssorhynchus) are peridomiciliary, entering houses to feed on blood and immediately leaving to settle on nearby vegetation. Anopheles nuneztovari proved to be zoophilic, crepuscular and peridomiciliary. These habits may change depending on a series of external factors, especially those related to human activity. There is a possibility that sibling species exist in the study area and they are being studied with reference to An. darlingi, An. albitarsis and An. nuneztovari. The present results do not suggest the existence of subpopulations of An. darlingi in the Brazilian Amazon.

Affinity and diversity indices for anopheline immature forms

As for the entire Amazon Region, malaria continues to be a major health public problem in Roraima that presented an Annual Parasitic Index of 85.4 in 2005, the highest in Brazil. Information on anopheline breeding sites is an essential component in malaria control strategies. Aiming to contribute to the limited knowledge on anopheline immature forms in Roraima, collections and breeding site observations were performed in 10 breeding sites around the capital city Boa Vista. Collections were carried out in the rainy and dry season periods between April 2004 and January 2005. Breeding sites comprised natural and artificial water reservoirs. A total of 623 immature forms were collected belonging to Anopheles albitarsis s.l., An.triannulatus s.l., An. nuneztovari/dunhami, An. braziliensis, An. evansae, An. oswaldoi s.l., An. strodei and An. darlingi. An. albitarsis and An. braziliensis were the most frequently found species. Eight larvae of An. darlingi were found in only one breeding site located in the forest. An. triannulatus/An. nuneztovari and An. albitarsis/An. braziliensis were the pairs of species that mostly occurred together. Both pair of species displayed the highest affinity index what might indicate a high compatibility for the same breeding conditions and/or a synergistic co-occurrence. Species diversity index was higher for the dry season.

Brazilian mosquito (Diptera: Culicidae) fauna: I. Anopheles species from Porto Velho, Rondônia state, western Amazon, Brazil

This study contributes to knowledge of Anopheles species, including vectors of Plasmodium from the western Brazilian Amazon in Porto Velho, Rondônia State. The sampling area has undergone substantial environmental changes as a consequence of agricultural and hydroelectric projects, which have caused intensive deforestation and favored habitats for some mosquito species. The purpose of this study was to diagnose the occurrence of anopheline species from collections in three locations along an electric-power transmission line. Each locality was sampled three times from 2010 to 2011. The principal adult mosquitoes captured in Shannon trap were Anopheles darlingi, An. triannulatus, An. nuneztovari l.s., An.gilesi and An. costai. In addition, larvae were collected in ground breeding sites for Anopheles braziliensis, An. triannulatus, An. darlingi, An. deaneorum, An. marajoara, An. peryassui, An. nuneztovari l.s. and An. oswaldoi-konderi. Anopheles darlingi was the most common mosquito in the region. We discuss Culicidae systematics, fauna distribution, and aspects of malaria in altered habitats of the western Amazon.

Espécies de Anopheles no município de Pinheiro (Maranhão), área endêmica de malária

A riqueza, abundância relativa, flutuação sazonal, preferência por ambiente (peri e intradomicílio) e horários de hematofagismo de espécies de Anopheles foram estudados no município de Pinheiro, Maranhão. As fêmeas foram capturadas mensalmente sobre iscas humanas de maio/1998 a abril/1999, das 18 às 6 horas. Foram coletados 1.321 espécimens pertencentes a 10 espécies de Anopheles, todas do subgênero Nyssorhynchus: A. argyritarsis com 62%, A. darlingi (21,7%), A. albitarsis (4,5%), A. galvaoi (4%), A. triannulatus (3,1%) e A. evansae (2,8%). As espécies A. nuneztovari, A. braziliensis, A. rondoni e A. strodei representaram juntas 1,9%. Os anofelinos ocorreram o ano todo, não havendo diferença significativa no número de exemplares capturados entre as estações chuvosa (51,7%) e seca (48,3%). A freqüência dos anofelinos no peridomicílio foi significativamente maior (p < 0,01) (82%) do que no intradomicílio (18%), preferindo sugar no crepúsculo vespertino e nas primeiras horas da noite.

Genetic variability among Anopheles species belonging to the Nyssorhynchus and Anopheles subgenera in the Amazon region

INTRODUCTION: Isoenzymatic analyses were performed involving species of the Nyssorhynchus and Anopheles subgenera in order to estimate the intra and interspecies genetic variability. METHODS: Mosquitoes were caught at different localities in the Amazon region. The collection and rearing of mosquitoes in the laboratory followed specific protocols. For the genetic variability analyses, the technique of horizontal electrophoresis on starch and starch-agarose gel with appropriate buffer systems was used. The alloenzyme variation was estimated using the Biosys-1 software. RESULTS: Out of the 13 loci, eight were polymorphic. Anopheles nuneztovari presented the largest number of alleles per locus, while the smallest number was detected in Anopheles marajoara from Macapá. The largest number of polymorphic loci was found for Anopheles marajoara from Maruanum and the smallest for Anopheles benarrochi (Guayará Mirim). Anopheles darlingi (Macapá) presented the greatest heterozygosity (Ho = 0.167 ± 0.071), while the lowest heterozygosity (Ho = 0.045 ± 0.019) was observed in Anopheles intermedius (Pacoval) of the subgenus Anopheles. Wright's F coefficient revealed considerable genetic structuring between the populations of Anopheles darlingi (Fst = 0.110) and between the populations of Anopheles marajoara (Fst = 0.082). CONCLUSIONS: Considering all the species studied, the genetic distance ranged from 0.008 to 1.114. The greatest distance was between Anopheles mattogrossensis and Anopheles oswaldoi, while the smallest was between the Anopheles benarrochi populations.

Evaluation of larvicidal activity and brine shrimp toxicity of rhizome extracts of Zingiber zerumbet (L.) Smith

Introduction In this study, we used dichloromethane (DCM) and methanol (MeOH) extracts of the Zingiber zerumbet rhizome to evaluate brine shrimp lethality and larvicidal activity on Aedes aegypti and Anopheles nuneztovari mosquitoes. Methods Bioassays were performed by exposing third-instar larvae of each mosquito species to the DCM or MeOH extracts. Results Probit analysis with DCM and MeOH extracts demonstrated efficient larvicidal activity against A. aegypti and A. nuneztovari larvae. Conclusions The DCM and MeOH extracts showed higher activity against A. nuneztovari larvae than against A. aegypti larvae, suggesting that the extracts have species-specific activity.

Larvicidal effects of endophytic and basidiomycete fungus extracts on Aedes and Anopheles larvae (Diptera, Culicidae)

Introduction In vitro bioassays were performed to access the larvicidal activity of crude extracts from the endophytic fungus Pestalotiopsis virgulata (Melanconiales, Amphisphaeriaceae) and the saprophytic fungus Pycnoporus sanguineus (Basidiomycetes, Polyporaceae) against the mosquitoes Aedes aegypti and Anopheles nuneztovari. Methods The extracts were tested at concentrations of 100, 200, 300, 400 and 500ppm. Ethyl acetate mycelia (EAM) extracts and liquid culture media (LCM) from Pe. virgulata and Py. sanguineus were tested against third instar larvae of Ae. aegypti and An. nuneztovari. Results The larvicidal activity of the EAM extracts from Pe. virgulata against Ae. aegypti had an LC50=101.8ppm, and the extract from the basidiomycete fungus Py. sanguineus had an LC50=156.8ppm against the Ae. aegypti larvae. The Pe. virgulata extract had an LC50=16.3ppm against the An. nuneztovari larvae, and the Py. sanguineus extract had an LC50=87.2ppm against these larvae. Conclusions These results highlight the larvicidal effect of EAM extracts from the endophyte Pe. virgulata against the two larval mosquitoes tested. Thus, Pe. virgulata and Py. sanguineus have the potential for the production of bioactive substances against larvae of these two tropical disease vectors, with An. nuneztovari being more susceptible to these extracts.

BIOLOGIA DE ANOFELINOS AMAZÔNICOS. XXL OCORRRÊNCIA DE ESPÉCIES DE ANOPHELES E OUTROS CULICÍDEOS NA ÁREA DE INFLUÊNCIA DA HIDRELÉTRICA DE BALBINA - CINCO ANOS APÓS O ENCHIMENTO DO RESERVATÓRIO

Um inquérito entomològico foi realizado na área de influência da Hidrelétrica de Balbina, situada a 146 km de Manaus, Amazonas, para avaliar os possíveis efeitos sobre as populações de Anophelese de outros culicídeos. Cinco anos após a formação do lago, An. darlingi, An. nuneztovarie An. triannulatusforam as espécies encontradas com maior freqüência nas coletas realizadas em 1. Rodovia BR-174, 2. Acceso á Usina Hidrelétrica de Balbina e 3. Área Uatumã-Morena. Para cada espécie os índices mosquito/homem/hora foram respectivamente: Area 1 - 0,57; 12,85; 0,43. Área 2 - 0; 3,75; 0,18 e Área 3 - 0; 26,38; 0,34. Representantes das duas primeiras espécies se mostraram positivas para Plasmodiumcom testes imunoenzimáticos. A prevalência de mosquitos positivos foi 1:35 para An. darlingie apenas 1:548 para An. nuneztovari.A densidade dos outros culicídeos foi baixa (Área 1 - 3,23 m/h/h; Área 2 - 4,5 m/h/h; Área 3 - 7,40 m/h/h) embora a diversidade foi comparável ( 32 espécies diferentes) com as encontradas em outras hidrelétricas construídas em rios de águas brancas ou claras da Amazônia. Nas águas pretas da Balbina, uma proliferação inicial de macrófitas foi seguida pela redução destas possivelmente pela falta de nutrientes na água. A diminuição no crescimento de macrófitas deve estar relacionada com a escassez de Mansoniasp. na área.

Structure of Anopheles (Diptera: Culicidae) population in areas with different degrees of human settlement: Cantá - Roraima - Brazil

Malaria has still been one of the most important endemic diseases in the Amazonian region. This study presents the impact of human settlements on the structure of Anopheles population. Diversity, abundance, richness and distribution of the genus Anopheles were observed in two areas with different levels of human settlement in the Cantá city, Roraima State, Northern Brazil. The influence of the dry and rainy seasons on mosquito populations was also observed. Mosquito captures were performed between 6:00 and 10:00 pm during the dry (February and November) and rainy (May and August) seasons at four different sites of each area. Among the 11 species of Anopheles identified through the adults' characteristics, An. albitarsis s.l. (45.5%) and An. darlingi (19.2%) were the most abundant in the more intensively anthropized area while An. triannulatus (19.2%) was more common in the less modified area. Other species found were An. nuneztovari (10.9%), An. oswaldoi (2.0%), An. evansae (1.7%), An. brasiliensis (0.6%), An. intermedius (0.3%), An. mediopunctatus (0.5%), An. periassui (0.08%) and An. argyritarsis (0.04%). The highest mosquitoes' population density was observed in May and the lowest one was observed in February and November. These results demonstrate the existence of a high diversity of anophelines in the study areas, showing that anthropic changes in the environment and climate variability affect both the population density and relative abundance of these vectors.

A cronologia da descoberta dos transmissores da malária na Amazônia brasileira

In the Amazon Region of Brazil, during the first three decades of this century, anophelines of the subgenus Nyssorhynchus not precisely identified to species were regarded as the probable malaria vectors. In 1931 and 1933 Anopheles darlingi, and in 1942-1946 An. aquasalis were confirmed as carriers, the former in the interior, the latter along the coast, because of their habits and salivary gland infection. An. albitarsis and An. braziliensis seemed to be occasional, secondary vectors. Forty years later, through immunological tests, other species are being pointed as naturally infected: An. triannulatus, An. nuneztovari, An. oswaldoi, An. strodei, An. galvaoi and An. peryassui. The importance of all incriminated species except An. darlingi (the main vector wherever present) and An. aquasalis has yet to be measured.

Fecundity, parity, and adult feeding relationships among Nyssorhynchus malaria vectors from Venezuela

Relative to their pre-engorgement weights, nulliparous Anopheles nuneztovari consumed significantly smaller blood meals than A. marajoara, A. triannulatus or A. aquasalis. When females were deprived of sugar before blood feeding, only one-quarter of A. nuneztovari, but more than two-thirds of A. marajoara, A. triannulatus and A. aquasalis matured eggs. Sugar feeding before blood, or two sucessive blood meals by sugar-deprived females, increased the proportion of nulliparous a. nuneztovari which developed eggs, but not significantly so. Nearly all individuals of nulliparous, sugar-fed A. marajoara, A. triannulatus and A. aquasalis matured eggs after one blood feeding. Among A. nuneztovari, A. marajoara and A. aquasalis that matured some eggs in the laboratory, there were no positive correlations between the number of eggs developed and relative vlood mealsize. However, blood meals larger than the mean size significantly increased the chance that A. nuneztovari would develop some eggs. Mean fecundities of gravid A. nuneztovari and A. marajoara reared in the laboratory were significantly lower than those of the same species captured at human bait in nature. Post-engorgement access to sugar by A. nuneztovari (captured at human bait) did not influence fecundity, but significantly enhanced survivorship and the proporticon of individuals which retained eggs. Release-recapture experiments revealed that relatively small blood meals are typical of A. nuneztovari only during the first gonotrophic cycle. We suggest that multiple blood feeding, seemingly necessary for most A. nuneztovari to develop a first clutch of eggs, may increase the probability of infection with Plasmodium vivax where this mosquito species is a primary vector.

Simian malaria at two sites in the Brazilian Amazon - II: Vertical distribution and frequency of anopheline species inside and outside the forest

An anopheline survey was carried out in two simian malaria areas in the Brazilian Amazon, Balbina and Samuel, to determine the potential vectors of Plasmodium brasilianum. The most abundant and/or acrodendrophilic anophelines in the forest and the most likely vector were Anopheles mediopunctatus, An. nuneztovari, An. oswaldoi, An. triannulatus and An. shannoni. An. darlingi and An. marajoara were captured essentially in anthropic habitats outside the forest and are unlikely to be involved in the transmission of P. brasilianum among monkeys within the forests and from monkeys to man in their surroundings in the Amazon.

Studies on the Bacillus sphaericus Larvicidal Activity against Malarial Vector Species in Amazonia

In this work, bioassays were carried out in laboratory conditions (average temperature 26 ± 2ºC) to test ten strains of Bacillus sphaericus, isolated from Brazilian soils against third instar larvae from anopheline species recorded as malaria vectors in Amazonian - Anopheles nuneztovari and An. darlingi. With the former mosquito, three strains - S2, S20 and S46 showed relative activity, in 24 and 48 hr exposure to the B. spahericus strains. With the latter only the S2 and S20 were effective in the 48 hr reading. The studied strains that showed the most adequate response in the Amazonian region were S2 and S20 showing broader and more efficient results. Therefore, S2 was the most effective when the 24 and 48 hr readings were considered, because it showed the greatest relative activity values.