Caracterización de hábitats larvales de anofelinos en el municipio Sifontes del estado Bolívar, Venezuela / Characterization of anophelines larval habitats in the municipality of Sifontes, Bolívar State, Venezuela

El municipio Sifontes, ubicado en el noreste del estado Bolívar, constituye el principal foco de malaria de Venezuela. Durante el quinquenio 2010-2014, se registró en el municipio un aumento considerable de la morbilidad con una fuerte tendencia al incremento, cerrando 2014 con la cifra record de 51.603 casos, 58% de la malaria del país en el año. Con el objeto de estudiar la distribución espacial de las larvas de anofelinos en los hábitats acuáticos y su relación con las variables ambientales, se hicieron colectas mensuales de larvas en hábitats representativos de los diferentes tipos existentes en la zona, entre septiembre 2002 y diciembre 2003. El Análisis de Correspondencia Canónica (CANOCO) indica que a nivel de hábitat (humedal), la presencia de las especies de Anopheles está determinada por el tipo y la dinámica hídrica del hábitat, mientras que a nivel de microhábitat (cucharonazo) las especies se ubican a lo largo de un gradiente dominado por el tipo de vegetación, y en menor grado por la luz solar y el color aparente del agua. Esto permitió establecer grupos de especies a priori, tales como las del subgénero Nyssorhynchus, asociadas a la luz solar y a ciertas plantas acuáticas, o las de los subgéneros Anopheles y Stethomyia, An. (Lophopodomyia) squamifemur y Chagasia bonneae asociadas a ambientes sombreados y carentes de vegetación. Los resultados ayudan a comprender mejor la relación de las especies de anofelinos con el medio ambiente y resaltan la importancia de variables como la dinámica hídrica, luz solar, vegetación y color aparente del agua para determinar su ocurrencia en el hábitat acuático.

The Municipality of Sifontes, located in the northeast of Bolivar State, is the main malaria foci in Venezuela. A considerable increase in malaria morbidity was recorded in the Municipality during the decade 2010-2014, with a record figure of 51.603 cases for 2014, 58% of the malaria for the country. In order to study the spatial distribution of anopheline inmature stages in the larval habitats and its relation to environmental variables, monthly collections were carried out in larval habitats representatives of the different types present in the area between September 2002 and December 2003. The Canonic Correspondance Analysis (CANOCO) showed that at the larval habitat level the Anopheles species is determined by the type and dynamics of the habitat, while at the microhabitat level (dip) the species are located along a gradient dominated by the type of vegetation, and in a lesser degree by the exposure to sun light and apparent water color. These allowed to established group of species a priori, such as those of the subgenus Nyssorhynchus associated to sun light and certain aquatic plants, or the subgenus Anopheles and Sthetomyia, An. squamifemur and Chagasia bonneae associated to shaded environments and lack of vegetation. The results help to understand the relationship of anopheline species with the environment and the importance of variables such s water dynamics, sun light, vegetation and water apparent color to determine its occurrence in the larval habitat.

Fluctuación poblacional y hábitat larval de anofelinos en el municipio Sifontes, estado Bolívar, Venezuela / Population fluctuation and larval habitat of anopheline in the Municipality of Sifontes, Bolivar State, Venezuela

El Municipio Sifontes, ubicado en el noreste del estado Bolívar, Venezuela, constituye uno de los principales focos de malaria del país debido a causas naturales y antrópicas.Durante el decenio 2004-2013, se registró en este municipio un aumento considerable del número de casos, cerrando 2013 con 42.981 casos, 56% de la malaria del país. Con el objeto de describir la dinámica poblacional de las principales especies de anofelinos, en fase pre-adulta, entre septiembre 2002 y diciembre 2003, se hicieron colectas mensuales en cuerpos de agua representativos de los diferentes tipos existentes en el municipio. Anopheles triannulatus Neiva & Pinto sensu lato fue la especie más abundante y ubicua en toda el área de estudio, seguida de An. albitarsis Lynch Arribalzaga s.l., mientras que An. darlingi Root fue encontrada principalmente en lagunas y ríos. La variabilidad estacional en la abundancia larval estuvo condicionada principalmente por la especie de anofelino y el tipo de hábitat que ésta coloniza, de tal forma que el efecto de la lluvia sobre la abundancia de las especies depende de la dinámica hídrica del hábitat larval, si bien en general, la abundancia de larvas tiende a ser mayor durante el periodo de transición lluvia-sequía y sequía. Los resultados de este estudio contribuyen a dilucidar la relación de la dinámica poblacional de los anofelinos con el patrón de lluvias en la región estudiada.

Sifontes Municipality in the north-east of Bolivar State is one of the main malaria foci in Venezuela due to both natural and anthropic factors. Between 2004 and 2013 a significant increase in the number of cases were reported for this region: at the close of 2013, 42.981 cases had been registered representing 56% of the total number of cases reported in the country. Between September 2002 and December 2003 anopheline larvae were collected monthly to study population fluctuations in different habitats representative of the study area. Anopheles triannulatus Neiva & Pinto sensu lato was the most abundant species collected followed by An. albitarsis Lynch Arribalzaga s.l., while An. darlingi Root was mainly found in lagoons and rivers. Seasonal variations in larval abundance were mainly determined by anopheline species and the type of larval habitat exploited by each one. Anopheline species are thus differentially influenced by rainfall according to the water dynamics of their larval habitats, but in general abundance is higher during the transitions between rainfall-drought and the dry season. These results help us to understand the relationships between anopheline population dynamics and rainfall patterns in this region. In addition, they contribute to our basic knowledge of the bio-ecology of anopheline vectors important for the epidemiology, surveillance and control of malaria in Sifontes Municipality.

Primer registro de Anopheles (Nyssorhynchus) oswaldoi B y Anopheles (Nys) albitarsis F en la cuenca del río Caura, Estado Bolívar, Venezuela / First record of anopheles (Nyssorhynchus) oswaldoi B y anopheles (Nys) albi-tarsis F from the Caura river basin, Bolívar State, Venezuela

Se registran por primera vez anopheles albitarsis F y anopheles oswaldoi B recolectadas en localidades de los municipios Sucre y Cedeño del estado Bolívar. Los análisis morfométricos de hembras adultas mostraron que los caracteres analizados en las manchas claras y oscuras de la vena Costa del ala y los tarsómeros de las patas posteriores para An. albitarsis F caen dentro de los rangos reportados para An. marajora sensu lato, mientras que para An. oswaldoi B los rangos de variación de los caracteres medidos están dentro del rango reportado para An. oswaldoi s.l., An. oswaldoi sensu stricto de Brasil y An. konderi. Sin embargo, el análisis de ADN mitocondrial (región código de barras, 658 pb) mostró una divergencia genética entre An. oswaldoi B y An. oswaldoi s.s. de 3,2%, mientras entre An. albirtarsis F y An. marajoara s.s. esta fue de 5,2%, valores que están por encima de los limites propuestos para delimitación de especies.

Anopheles albitarsis F and Anopheles oswaldoi B were first recorded from collections in Sucre and Cedeño Municipalities, Bolivar State. Morphometric analysis of dark and pale spots on wing Costa and hind tarsomeres of adult females, showed that the range of variation for An. albitarsis F are within the reported ranges for An. marajoara sensu latu For An. oswaldoi B the range of variation are within the ranges reported for An. oswaldoi s.l., An. oswaldoi sensu stricto from Brazil and An. konderi. DNA mitochondrial analysis (Barcode region 658 bp) showed 3.2% of genetic divergence between An. oswaldoi B and An. oswaldoi s.s., while this divergence was 5.2% between An. albirtarsis F and An. marajoara s.s. Both these values are above the proposed limits for species delimitation.

Mosquito Anthropophily: implications on malaria transmission in the northern Brazilian Amazon

Seasonal variation of adults and larvae of anophelines was studied during 2003 and 2004 in Roraima State, located in the Northern region of Brazilian Amazon. Species diversity increased with distance of capture to human dwellings. Greater diversity was found in extradomiciliary collections than in peridomiciliary or intradomiciliary. A significant association between Anopheles darlingi Root and An. albitarsis (s.l.) Arribálzaga (Diptera: Culicidae) breeding sites and the proximity to human dwellings was observed. Malaria Sporozoite Antigen Panel Assay (VectestTM Malaria) indicated An. albitarsis s.l. as one of the local vectors in the studied area. In this study, an index to describe the anthropophilic behavior of each anopheline species is proposed.

Espécies de Anopheles (Diptera, Culicidae) em municípios com risco e autoctonia de malária no estado de Goiás / Species of Anopheles (Diptera, Culicidae) collected in counties of risk and autochthonous cases of malaria in Goiás State, Brazil

Neste estudo, avaliou-se a frequência de espécies de Anopheles (Diptera, Culicidae) em municípios com risco e autoctonia de malária no estado de Goiás, no período de 1999 a 2006. Foram capturados 2.867 exemplares de 11 espécies de Anopheles em 26 municípios. A frequência das espécies Anopheles evansae, An. albitarsis, An. argyritarsis s.l., An. parvus, An. galvaoi e An. oswaldoi foi estatisticamente igual, porém significativamente maior do que a das espécies An. mediopunctatus, An. maculipes, An. braziliensis e An. kompi (p menor que 0,05). As espécies que apresentaram maior diversidade foram An. darlingi e An. argyritarsis. No período estudado, foram registrados 1.018 casos importados de malária e 23 casos autóctones. Dos casos autóctones diagnosticados, 21,7por cento foram causados por Plasmodium falciparum e 78,3por cento por P. vivax. Nos casos importados de malária, a frequência foi muito similar à dos autoctones, sendo de 27,2por cento e 72,8por cento para P. falciparum e P. vivax, respectivamente.

The Anopheles albitarsis complex with the recognition of Anopheles oryzalimnetes Wilkerson and Motoki, n. sp. and Anopheles janconnae Wilkerson and Sallum, n. sp. (Diptera: Culicidae)

The Anopheles (Nyssorhynchus) albitarsis complex includes six species: An. albitarsis, Anopheles oryzalimnetes Wilkerson and Motoki, n. sp., Anopheles marajoara, Anopheles deaneorum, Anopheles janconnae Wilkerson and Sallum, n. sp. and An. albitarsis F. Except for An. deaneorum, species of the complex are indistinguishable when only using morphology. The problematic distinction among species of the complex has made study of malaria transmission and ecology of An. albitarsis s.l. difficult. Consequently, involvement of species of the An. albitarsis complex in human Plasmodium transmission is not clear throughout its distribution range. With the aim of clarifying the taxonomy of the above species, with the exception of An. albitarsis F, we present comparative morphological and morphometric analyses, morphological redescriptions of three species and description of two new species using individuals from populations in Brazil, Paraguay, Argentina and Venezuela. The study included characters from adult females, males, fourth-instar larvae, pupae and male genitalia of An. albitarsis, An. marajoara, An. deaneorum and An. oryzalimnetes n. sp. For An. janconnae n. sp. only characters of the female, male and male genitalia were analyzed. Fourth-instar larvae, pupae and male genitalia characteristics of all five species are illustrated. Bionomics and distribution data are given based on published literature records.

Man biting rate seasonal variation of malaria vectors in Roraima, Brazil

Malaria control has been directed towards regional actions where more detailed knowledge of local determinants of transmission is of primary importance. This is a short report on range distribution and biting indices for Anopheles darlingi and An. albitarsis during the dry and rainy season that follows river level variation in a savanna/alluvial forest malaria system area in the Northern Amazon Basin. Distribution range and adult biting indices were at their highest during the rainy season for both An. darlingi and An. albitarsis. During the rainy season the neighboring alluvial forest was extensively flooded. This coincided with highest rates in malaria transmission with case clustering near the river. As the river receded, anopheline distribution range and density decreased. This decrease in distribution and density corresponded to a malaria decrease in the near area. An exponential regression function was derived to permit estimations of An. darlingi distribution over specified distances. Anopheline spatio-temporal variations lead to uneven malaria case distribution and are of important implications for control strategies.

Karyotype of Brazilian Anopheles albitarsis sensu lato (Diptera: Culicidae)

Anopheles (Nyssorhynchus) albitarsis sensu lato is an important malaria vector in Brazil, especially in the Brazilian Amazon region. Chromosome preparations of fourth-instar larvae of A. albitarsis from Iranduba and Coari (AM) and Ilha Comprida (SP) were analyzed for karyotype determination and to improve cytogenetic identification of this species. Anopheles albitarsis possesses 2n = 6 chromosomes, with two pairs (submetacentric and metacentric) of autosomes and one pair of sex chromosomes, with X-Y dimorphism. The sex pair is homomorphic and acrocentric in females and heteromorphic in males, with a punctiform Y chromosome. Somatic pairing was detected in the prometaphase and metaphase chromosomes of the three A. albitarsis populations. Apparently, sex chromosome evolution in the Culicidae does not function as does evolution in the Culicidae, since it occurs in the subfamily Anophelinae, which possesses heteromorphic sex chromosomes and is regarded as primitive, based on several criteria. These karyotype data on the albitarsis complex reinforce the hypothesis that sex chromosome evolution in the subfamily Anophelinae is conserved, and the variation revealed in the mean size of chromosomes in three populations indicates that selective pressure in these populations is occurring only at a genetic level.

Padrões ontogenéticos das Esterases, Leucina Aminopeptidase e X-Glicerofosfato Desidrogenase em Anopheles (Nyssorhynchus) Albitarsis lynch-arribálzaga, 1878 (Diptera: Culicidae)

Modifications in genetic expression were observed in the esterase, leucine aminopeptidase and x-glycerophosphate dehydrogenase systems during ontogenetic development of Anopheles albitarsis. The esterase revealed four regions of activity. Esterase 1 was detected in 4th stage larvae and in pupae. Esterase 2 and 4 were present during all stages of development and esterase 3 appeared mainly in larvae and rarely in pupae. Four regions of activity were also observed in leucine aminopeptidase during ontogeny. The LAP1 and LAP2 were characteristic of larvae and LAP3 was present only in pupae and adults. LAP4 was detected in all three stages, x-glycerophosphate dehydrogenase presented one activity band whose intensity increased with development.

Modificações na expressão gênica foram observadas nos sistemas esterase, leucina aminopeptidase e x-glicerofosfato desidrogenase, durante o desenvolvimento ontogenético de Anopheles albitarsis. A esterase revelou quatro regiões de atividade, sendo a esterase 1 detectada apenas em larvas de 4º estádio velhas e em pupas, as esterases 2 e 4 foram presentes durante todo o desenvolvimento, e a esterase 3 revelou-se praticamente apenas em larvas e raríssimas vezes em pupas. Também foram observadas quatro regiões de atividade na leucina aminopeptidase, durante a ontogenia. As LAP1 c LAP2 foram características de larvas, a LAP3 esteve presente somente em pupas e adultos e a LAP4 foi detectada nos três diferentes estágios. Uma única região foi observada para a x-glicerofosfato desidrogenase e a intensidade de sua atividade cresce à medida que se aproxima o estágio adulto.