Factors shaping the gut bacterial community assembly in two main Colombian malaria vectors.

BACKGROUND: The understanding of the roles of gut bacteria in the fitness and vectorial capacity of mosquitoes that transmit malaria, is improving; however, the factors shaping the composition and structure of such bacterial communities remain elusive. In this study, a high-throughput 16S rRNA gene sequencing was conducted to understand the effect of developmental stage, feeding status, species, and geography on the composition of the gut bacterial microbiota of two main Colombian malaria vectors, Anopheles nuneztovari and Anopheles darlingi. RESULTS: The results revealed that mosquito developmental stage, followed by geographical location, are more important determinants of the gut bacterial composition than mosquito species or adult feeding status. Further, they showed that mosquito gut is a major filter for environmental bacteria colonization. CONCLUSIONS: The sampling design and analytical approach of this study allowed to untangle the influence of factors that are simultaneously shaping the microbiota composition of two Latin-American malaria vectors, essential aspect for the design of vector biocontrol strategies.

Population dynamics of Anopheles nuneztovari in Colombia.

Anopheles nuneztovari is an important Colombian malaria vector widespread on both sides of the Andean Mountains, presenting morphological, behavioral and genetic heterogeneity throughout the country. The aim of this study was to evaluate whether the population structure and distribution of An. nuneztovari in Colombia are associated with ecological and physical barriers present in a heterogeneous landscape. Further, differences in behavior were addressed. A total of 5392 specimens of An. nuneztovari were collected. Mitochondrial and nuclear marker analyses detected subdivision among the northwest-west, northeast and east populations. For both markers, isolation by distance (~53%) and isolation by resistance (>30%) were determinants of population genetic differentiation. This suggests that physical barriers, geographical distance and ecological differences on both sides of the Andean Mountains promoted the genetic differentiation and population subdivision of An. nuneztovari in Colombia. This species showed the highest biting activity after 20:00h; indoor and outdoor preferences were found in all localities. These results indicated that the most effective interventions for controlling vector populations on both sides of the Andes need to be region-specific.

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.

Anopheles goeldii Rozeboom & Gabaldón (Diptera, Culicidae): a species of the Nuneztovari Complex of Anopheles Meigen

Anopheles (Nyssorhynchus) goeldii Rozeboom & Gabaldón, 1941, a species of the Nuneztovari Complex, was described based on morphological characteristics of the male, female, larva, pupa, and eggs. The typelocality is Boa Vista (= Fordlândia), a district in the vicinity of Rio Tapajós, in the municipality of Aveiro, in the state of Pará, Brazil. Anopheles goeldii is redescribed based on morphological traits of the fourth instar larva, pupa, egg, and male and female. DNA sequences from the cytochrome oxidase subunit I (COI barcoderegion) of the mitochondrial genome were utilized for species characterization. Specimens of An. goeldiifrom the Pará, Amapá, and Amazonas states were employed to redescribe the species and to compare with morphologically similar taxa...

Molecular evidence for a single taxon, Anopheles nuneztovari s.l., from two endemic malaria regions in Colombia

To elucidate the Anopheles nuneztovari s.l. taxonomic status at a microgeographic level in four malaria endemic localities from Antioquia and Córdoba, Colombia, fragments of the cytochrome oxidase subunit I (COI) and the white gene were used. The COI analysis showed low genetic differentiation with fixation index (F ST) levels between -0.02-0.137 and Nm values between 3-∞, indicating the presence of high gene flow among An. nuneztovari s.l. populations from the four localities. The COI network showed a single most common haplotype, type 1 (n = 55), present in all localities, as the likely ancestral haplotype. Analysis of the white gene showed that An. nuneztovari s.l. populations from both departments grouped with haplotypes 19 and 20, which are part of lineage 3 reported previously. The results of the present study suggest that An. nuneztovari s.l. is a single taxon in the area of the present study.

Morphological analysis of three populations of Anopheles (Nyssorhynchus) nuneztovari Gabaldón (Diptera: Culicidae) from Colombia

Based on the results of comparative analyses of 1,039 specimens of several progenies of Anopheles nuneztovarifrom three localities in Colombia, eight costal wing spot patterns were observed. Patterns I and III were the most frequent: 77.96 percent and 11.36 percent, respectively. Using the diagnostic characters ratio of the length of the basal dark area of hind tarsomere II/length of hind tarsomere II, ratio of the length of the humeral pale spot/length of the pre-humeral dark spot, and the ratio of the length of the subcostal pale spot/length of the distal sector dark spot (DS-III2/Ta-III2, HP/PHD, SCP/DSD) approximately 5 percent of the adult females were misidentified as a species of Nyssorhynchus, different from An. nuneztovari. Approximately 5 percent of the specimens showed DS-III2/Ta-III2 ratio less than 0.25 (range 0.21 - 0.24), and among them 3.34 percent shared a HP/PHD ratio less than 1.50. Consequently, 1.52 percent of An. nuneztovari individuals can be misidentified as Anopheles oswaldoi. In those specimens with the DS-III2/Ta-III2 ratios higher than 0.25, 34.45 percent displayed SCP/DSD values greater than 0.50 and of these, 3.65 percent displayed HP/PHD values greater than 1.8. This combination of characters could lead one to misidentify samples of An. nuneztovari as Anopheles rangeli. Similarly, 2.43 percent of the females could be identified erroneously as either Anopheles aquasalis or Anopheles benarrochi. Individuals with a HP/PHD ratio greater than 2.0, could be misidentified as Anopheles trinkae, Anopheles strodei or Anopheles evansae. A distinct combination of diagnostic characters for An. nuneztovari from Colombia is proposed.