Genetic structure of Anopheles (Nyssorhynchus) marajoara (Diptera: Culicidae) in Colombia

Updating the bionomy and geographical distribution of Anopheles (Nyssorhynchus) albitarsis F: A vector of malaria parasites in northern South America

Anopheles albitarsis F is a putative species belonging to the Albitarsis Complex, recognized by rDNA, mtDNA, partial white gene, and microsatellites sequences. It has been reported from the island of Trinidad, Venezuela and Colombia, and incriminated as a vector of malaria parasites in the latter. This study examined mitochondrially encoded cytochrome c oxidase I (MT-CO1) sequences of An. albitarsis F from malaria-endemic areas in Colombia and Venezuela to understand its relations with other members of the Complex, revised and update the geographical distribution and bionomics of An. albitarsis F and explore hypotheses to explain its phylogenetic relationships and geographical expansion. Forty-five MT-CO1 sequences obtained in this study were analyzed to estimate genetic diversity and possible evolutionary relationships. Sequences generated 37 haplotypes clustered in a group where the genetic divergence of Venezuelan populations did not exceed 1.6% with respect to Colombian samples. Anopheles albitarsis F (π = 0.013) represented the most recent cluster located closer to An. albitarsis I (π = 0.009). Barcode gap was detected according to Albitarsis Complex lineages previously reported (threshold 0.014–0.021). Anopheles albitarsis F has a wide distribution in northern South America and might play an important role in the transmission dynamics of malaria due to its high expansion capacity. Future studies are required to establish the southern distribution of An. albitarsis F in Venezuela, and its occurrence in Guyana and Ecuador.

Microevolution of medically important mosquitoes - A review

This review intends to discuss central issues regarding the microevolution of mosquito (Culicidae) vectors of several pathogens and how this process impacts vector biology, disease transmission, and vector control attempts. On the microevolutionary context, it comparatively discusses the current knowledge on the population genetics of representatives of the genera Aedes, Anopheles and Culex, and comments on insecticide resistance of culicids. It also discusses other biological aspects of culicids that are not usually addressed in microevolutionary studies, such as vectorial competence, endosymbiosis, and wing morphology. One conclusion is that mosquitoes are highly genetically variable, adaptable, fast evolving, and have versatile vectorial competence. Unveiling microevolutionary patterns is fundamental for the design and maintenance of all control programs. Sampling methods for assessing microevolution must be standardized and must follow meaningful guidelines, such as those of "landscape genetics". A good understanding of microevolution requires more than a collection of case studies on population genetics and resistance. Future research could deal not only with the microevolution sensu stricto, but also with evolutionarily meaningful issues, such as inheritable characters, epigenetics, physiological cost-free plasticity, vector immunity, symbiosis, pathogen-mosquito co-evolution and environmental variables. A genotyping panel for seeking adaptive phenotypes as part of the standardization of population genetics methods is proposed. The investigative paradigm should not only be retrospective but also prospective, despite the unpredictability of evolution. If we integrate all suggestions to tackle mosquito evolution, a global revolution to counter vector-borne diseases can be provoked.

Morphometric variations of two populations of Anopheles albitarsis F (Diptera: Culicidae) in the Orinoquia region, Colombia

Introducción. Anopheles albitarsis F ha sido registrada con infección natural por Plasmodium falciparum. En la Orinoquía, se encuentra en simpatría con Anopheles darlingi, un vector primario de malaria.Objetivo. Determinar variaciones morfométricas en caracteres diagnósticos de ala y pata posterior de mosquitos adultos procedentes de dos poblaciones naturales de la Orinoquía, donde la malaria constituye un problema de salud pública.Materiales y métodos. Se analizaron, mediante morfometría lineal y geométrica, los patrones de manchas de la vena Costa del ala de hembras silvestres, de hembras obtenidas de series entomológicas y de isofamilias. Se estimó la forma y el tamaño alar. El segundo tarsómero posterior se analizó por morfometría lineal.Resultados. Se observaron dos patrones de manchas de la vena Costa; se encontraron diferencias estadísticamente significativas en el tamaño y forma alar (p<0.05) entre las hembras silvestres y las obtenidas en condiciones de laboratorio. Para las poblaciones estudiadas, se proponen como caracteres diagnósticos la proporción PHD/HP de 1.17-1.19 en la vena Costa y 0.38-0.54 para la proporción DSIII2/TaIII2 del segundo tarsómero posterior de la pata posterior.Conclusión. Las poblaciones estudiadas de An. albitarsis F presentaron diferencias significativas entre las hembras silvestres y las obtenidas en condiciones de laboratorio, no solo en el tamaño de las alas, sino también en la forma. Se presentan nuevos rangos para los caracteres diagnósticos de la especie.

[Anopheles (Díptera: Culicidae) vectors of malaria in Puerto Carreño municipality, Vichada, Colombia]

INTRODUCTION

The study of the biological aspects of Anopheles spp., strengthens the entomological surveillance.

OBJECTIVE

To determine biological aspects and behavior of adult Anopheles mosquitoes in the urban area of Puerto Carreño municipality, Vichada, Colombia.

MATERIALS AND METHODS

Wild anophelines were collected landing on humans both indoors and outdoors between 18:00h and 06:00h for 50 min/h during two consecutive nights/month for eight months in the urban area of Puerto Carreño. The biting rate activity, the natural infection by Plasmodium falciparum and P. vivax VK247 and VK210 using ELISA, and the annual entomological inoculation rate were determined for each species. The members of the Albitarsis complex were determined by amplificacion of the white gene by polymerase chain reaction.

RESULTS

In order of abundance the species found were An. darlingi (n=1,166), An. marajoara sensu stricto (n=152), An. braziliensis (n=59), An. albitarsis F (n=25), An. albitarsis sensu lato (n=16), An. argyritarsis (n=3) and An. oswaldoi sensu lato (n=2). An. darlingi showed two activity peaks between 21:00 to 22:00 and 05:00 to 06:00 hours outdoors and between 21:00 to 22:00 and 04:00 to 05:00 indoors. Natural infection of this species was found with P. vivax VK210 and its annual entomological inoculation rate was 2. Natural infection of An marajoara sensu stricto with P. falciparum was found, with an annual entomological inoculation rate of 5 and a peak biting activity between 18:00 to 19:00 hrs both indoors and outdoors.

CONCLUSION

Transmission of malaria in the urban area of Puerto Carreño, Vichada, can occur by An. darlingi and An. marajoara s.s.

Wing geometric morphometrics and molecular assessment of members in the Albitarsis Complex from Colombia

Malaria parasites are transmitted to humans by female mosquitoes of the genus Anopheles. The Albitarsis Complex harbours at least eight species not readily differentiable by morphology. This complicates the determination of those species involved in malaria transmission and the implementation of targeted and effective vector control strategies. In Colombia, there is little information about the identity and distribution of the Albitarsis Complex members. In this work, COI DNA barcoding was used to assign specimens Anopheles albitarsis s.l. to any of the previously designated species of the Albitarsis Complex. Two molecular operational taxonomic units (MOTUs), differentially distributed in Colombia, were detected, A. albitarsis I in the NW and NE, and A. albitarsis F, E and NE Colombia. In contrast, nuclear white gene and ITS2 sequence analyses did not allow differentiating between the MOTUs. Wing landmark-based geometric morphometrics applied to explore intertaxa phenotypic heterogeneity showed a subtle but significant difference in size, while shape did not allow the separation of the MOTUs. In general, the multiple marker analysis was not supportive of the existence in Colombia of more than one species of the Albitarsis Complex.

Microgeographic spatial structuring of Triatoma infestans (Hemiptera: Reduviidae) populations using wing geometric morphometry in the Argentine Chaco

We investigated the occurrence of spatial structuring in Triatoma infestans (KLug) (Hemiptera: Reduviidae) populations 12 yr after the last community-wide insecticide spraying campaign in rural Pampa del Indio, in the Gran Chaco of northeastern Argentina. In total, 172 male and 149 female right wings collected at 16 georeferenced sites with at least 10 individuals of the same sex were analyzed using geometric morphometry. Mean female body length and wing centroid size (CS) were significantly larger than for males. Log-transformed CS and length were significantly and positively correlated both for males and females. Males collected in domiciles had significantly smaller CS than those collected in peridomestic structures both closed (kitchens or storerooms) or open (chicken coops), in agreement with our previous results elsewhere in the dry Argentine Chaco. Female wing CS was not significantly different between ecotopes. Wing shape analyses showed the occurrence of significant geographic structuring in males and females combined and in males only. Male wings showed a strong association between Mahalanobis distance and geographic distance. In general, Mahalanobis distances were significantly different between collection sites located > 4 km apart. For collection sites located < 4 km apart, the greater the geographic distance the larger the difference in wing shape variables. Among females, only a partial correspondence between geographic groups and Mahalanobis distances was recorded. The strong spatial structuring found in T. infestans populations may be useful for the identification of putative reinfestation sources after vector control interventions.

Anopheles (Díptera: Culicidae) vectors of malaria in Puerto Carreño municipality, Vichada, Colombia

Introducción. El estudio de los aspectos de la biología de los mosquitos Anopheles spp. fortalece la vigilancia entomológica.Objetivo. Determinar los aspectos de la biología y el comportamiento de las especies adultas del género Anopheles presentes en el área urbana de Puerto Carreño.Materiales y métodos. Se capturaron Anopheles spp. silvestres que se habían posado en personas, en el intradomicilio y peridomicilio de viviendas ubicadas en el área urbana del municipio de Puerto Carreño (Vichada), entre las 18:00 y las 06:00 horas, durante dos noches consecutivas por mes y durante ocho meses. Se determinó la actividad de picadura para cada especie, la infección natural por Plasmodium falciparum y P. vivax VK247 y VK210 mediante la técnica ELISA, y se determinó la tasa de inoculación entomológica. Los individuos pertenecientes al complejo Albitarsis se determinaron mediante amplificación en cadena de la polimerasa del fragmento del gen white.Resultados. En orden de abundancia, se encontraron: An. darlingi (n=1.166), An. marajoara sensu stricto (n=152), An. braziliensis (n=59), An. albitarsis F (n=25), An. albitarsis sensu lato (n=16), An. argyritarsis (n=3) y An. oswaldoi sensu lato (n=2). Anopheles darlingi registró dos picos de actividad de picadura entre las 21:00-22:00 y las 5:00-06:00 horas en el peridomicilio y, entre las 21:00-22:00 y las 04:00-05:00 horas, en el intradomicilio. Esta especie se encontró naturalmente infectada por P. vivax VK210 y registró una tasa de inoculación entomológica de dos para el año. Anopheles marajoara s.s. se encontró naturalmente infectado por P. falciparum y registró una tasa de inoculación entomológica de 5 para el año, con un máximo de actividad de picadura entre las 18:00 y las 19:00 horas, tanto en el intradomicilio como en el peridomicilio.Conclusión. Es posible que exista transmisión de malaria en el área urbana de Puerto Carreño (Vichada) y An. darlingi y An. marajoara s.s. serían las especies incriminadas.

DNA barcoding reveals both known and novel taxa in the Albitarsis Group (Anopheles: Nyssorhynchus) of Neotropical malaria vectors

Background

Mosquitoes belonging to the Albitarsis Group (Anopheles: Nyssorhynchus) are of importance as malaria vectors across the Neotropics. The Group currently comprises six known species, and recent studies have indicated further hidden biodiversity within the Group. DNA barcoding has been proposed as a highly useful tool for species recognition, although its discriminatory utility has not been verified in closely related taxa across a wide geographic distribution.

Methods

DNA barcodes (658 bp of the mtDNA Cytochrome c Oxidase - COI) were generated for 565 An. albitarsis s.l. collected in Argentina, Brazil, Colombia, Paraguay, Trinidad and Venezuela over the past twenty years, including specimens from type series and type localities. Here we test the utility of currently advocated barcoding methodologies, including the Kimura-two-parameter distance model (K2P) and Neighbor-joining analysis (NJ), for determining species delineation within mosquitoes of the Neotropical Albitarsis Group of malaria vectors (Anopheles: Nyssorhynchus), and compare results with Bayesian analysis.

Results

Species delineation through barcoding analysis and Bayesian phylogenetic analysis, fully concur. Analysis of 565 sequences (302 unique haplotypes) resolved nine NJ tree clusters, with less than 2% intra-node variation. Mean intra-specific variation (K2P) was 0.009 (range 0.002 - 0.014), whereas mean inter-specific divergence were several-fold higher at 0.041 (0.020 - 0.056), supporting the reported "barcoding gap". These results show full support for separate species status of the six known species in the Albitarsis Group (An. albitarsis s.s., An. albitarsis F, An. deaneorum, An. janconnae, An. marajoara and An. oryzalimnetes), and also support species level status for two previously detected lineages - An. albitarsis G &An. albitarsis I (designated herein). In addition, we highlight the presence of a unique mitochondrial lineage close to An. deaneorum and An. marajoara (An. albitarsis H) from Rondônia and Mato Grosso in southwestern Brazil. Further integrated studies are required to confirm the status of this lineage.

Conclusions

DNA barcoding provides a reliable means of identifying both known and undiscovered biodiversity within the closely related taxa of the Albitarsis Group. We advocate its usage in future studies to elucidate the vector competence and respective distributions of all eight species in the Albitarsis Group and the novel mitochondrial lineage (An. albitarsis H) recovered in this study.

A new mtDNA COI gene lineage closely related to Anopheles janconnae of the Albitarsis complex in the Caribbean region of Colombia

An understanding of the taxonomic status and vector distribution of anophelines is crucial in controlling malaria. Previous phylogenetic analyses have supported the description of six species of the Neotropical malaria vector Anopheles (Nyssorhynchus) albitarsis s.l. (Diptera: Culicidae): An. albitarsis, Anopheles deaneorum, Anopheles marajoara, Anopheles oryzalimnetes, Anopheles janconnae and An. albitarsis F. To evaluate the taxonomic status of An. albitarsis s.l. mosquitoes collected in various localities in the Colombian Caribbean region, specimens were analyzed using the complete mitochondrial DNA cytochrome oxidase I (COI) gene, the ribosomal DNA (rDNA) internal transcribed spacer 2 (ITS2) region and partial nuclear DNA white gene sequences. Phylogenetic analyses of the COI gene sequences detected a new lineage closely related to An. janconnae in the Caribbean region of Colombia and determined its position relative to the other members of the complex. However, the ITS2 and white gene sequences lacked sufficient resolution to support a new lineage closely related to An. janconnae or the An. janconnae clade. The possible involvement of this new lineage in malaria transmission in Colombia remains unknown, but its phylogenetic closeness to An. janconnae, which has been implicated in local malaria transmission in Brazil, is intriguing.

Malaria vector species in Colombia: a review

Here we present a comprehensive review of the literature on the vectorial importance of the major Anopheles malaria vectors in Colombia. We provide basic information on the geographical distribution, altitudinal range, immature habitats, adult behaviour, feeding preferences and anthropophily, endophily and infectivity rates. We additionally review information on the life cycle, longevity and population fluctuation of Colombian Anopheles species. Emphasis was placed on the primary vectors that have been epidemiologically incriminated in malaria transmission: Anopheles darlingi, Anopheles albimanus and Anopheles nuneztovari. The role of a selection of local, regional or secondary vectors (e.g., Anopheles pseudopunctipennis and Anopheles neivai) is also discussed. We highlight the importance of combining biological, morphological and molecular data for the correct taxonomical determination of a given species, particularly for members of the species complexes. We likewise emphasise the importance of studying the bionomics of primary and secondary vectors along with an examination of the local conditions affecting the transmission of malaria. The presence and spread of the major vectors and the emergence of secondary species capable of transmitting human Plasmodia are of great interest. When selecting control measures, the anopheline diversity in the region must be considered. Variation in macroclimate conditions over a species' geographical range must be well understood and targeted to plan effective control measures based on the population dynamics of the local Anopheles species.