Nicolás Jaramillo-O

Rhodnius barretti, a new species of Triatominae (Hemiptera: Reduviidae) from western Amazonia

Rhodnius barretti , a new triatomine species, is described based on adult specimens collected in rainforest environments within the Napo ecoregion of western Amazonia (Colombia and Ecuador). R. barretti resembles Rhodnius robustus s.l. , but mitochondrial cytochrome b gene sequences reveal that it is a strongly divergent member of the “robustus lineage”, i.e., basal to the clade encompassing Rhodnius nasutus , Rhodnius neglectus , Rhodnius prolixus and five members of the R. robustus species complex. Morphometric analyses also reveal consistent divergence from R. robustus s.l. , including head and, as previously shown, wing shape and the length ratios of some anatomical structures. R. barretti occurs, often at high densities, in Attalea butyracea and Oenocarpus bataua palms. It is strikingly aggressive and adults may invade houses flying from peridomestic palms. R. barretti must therefore be regarded as a potential Trypanosoma cruzi vector in the Napo ecoregion, where Chagas disease is endemic.

Genetic, Cytogenetic and Morphological Trends in the Evolution of the Rhodnius (Triatominae: Rhodniini) Trans-Andean Group

The Rhodnius Pacific group is composed of three species: Rhodnius pallescens, R. colombiensis and R. ecuadoriensis, which are considered important vectors of trypanosomes (Trypanosoma cruzi and T. rangeli) infecting humans. This group is considered as a recent trans-Andean lineage derived from the widespread distributed sister taxa R. pictipes during the later uplift of northern Andes mountain range. The widest spread species R. pallescens may be a complex of two divergent lineages with different chromosomal attributes and a particular biogeographical distribution across Central America and Colombia with several southern populations in Colombia occupying the same sylvatic habitat as its sister species R. colombiensis. Although the taxonomy of Rhodnius Pacific group has been well studied, the unresolved phylogenetic and systematic issues are the target of this paper. Here we explore the molecular phylogeography of this species group analyzing two mitochondrial (ND4 and cyt b) and one nuclear (D2 region of ribosomal 28S gene) gene sequences. The molecular analyses suggest an early divergence of the species R. ecuadoriensis and R. colombiensis, followed by a recent expansion of R. pallescens lineages. The phylogenetic relationship between sympatric R. pallescens Colombian lineage and R. colombiensis was further explored using wing morphometry, DNA genome size measurements, and by analyzing chromosomal behavior of hybrids progeny obtained from experimental crosses. Our results suggest that the diversification of the two R. pallescens lineages was mainly influenced by biogeographical events such as (i) the emergence of the Panama Isthmus, while the origin and divergence of R. colombiensis was associated with (ii) the development of particular genetic and chromosomal features that act as isolation mechanisms from its sister species R. pallescens (Colombian lineage). These findings provide new insights into the evolution of the Rhodnius Pacific group and the underlying biological processes that occurred during its divergence.

Eco-geographical differentiation among Colombian populations of the Chagas disease vector Triatoma dimidiata (Hemiptera: Reduviidae)

Triatoma dimidiata is currently the main vector of Chagas disease in Mexico, most Central American countries and several zones of Ecuador and Colombia. Although this species has been the subject of several recent phylogeographic studies, the relationship among different populations within the species remains unclear. To elucidate the population genetic structure of T. dimidiata in Colombia, we analyzed individuals from distinct geographical locations using the cytochrome c oxidase subunit 1 gene and 7 microsatellite loci. A clear genetic differentiation was observed among specimens from three Colombian eco-geographical regions: Inter Andean Valleys, Caribbean Plains and Sierra Nevada de Santa Marta mountain (SNSM). Additionally, evidence of genetic subdivision was found within the Caribbean Plains region as well as moderate gene flow between the populations from the Caribbean Plains and SNSM regions. The genetic differentiation found among Colombian populations correlates, albeit weakly, with an isolation-by-distance model (IBD). The genetic heterogeneity among Colombian populations correlates with the eco-epidemiological and morphological traits observed in this species across regions within the country. Such genetic and epidemiological diversity should be taken into consideration for the development of vector control strategies and entomological surveillance.

Spatial and Temporal Dynamics of Aedes aegypti Larval Sites in Bello, Colombia

ABSTRACT: Counts of immature stages of the mosquito Aedes aegypti have been used to calculate several entomological indices of dengue vector abundance. Some studies have concluded that these indices can be used as indicators of dengue epidemic risk, while other studies have failed to find a predictive relationship. Ecological niche models have been able to predict distributional patterns in space and time, not only of vectors, but also of the diseases that they transmit. In this study, we used Landsat 7 ETM+ images and two niche-modeling algorithms to estimate the local-landscape ecological niche and the dynamics of Ae. aegypti larval habitats in Bello, Colombia, and to evaluate their potential spatial and temporal distribution. Our models showed low omission error with high confidence levels: about 13.4% of the area presents conditions consistently suitable for breeding across the entire study period (2002–2008). The proportion of neighborhoods predicted to be suitable showed a positive association with dengue case rates, whereas the vector-focused Bretau index had no relationship to case rates. As a consequence, niche models appear to offer a superior option for predictive evaluation of dengue transmission risk and anticipating the potential for outbreaks.

Morphometric and molecular evidence of intraspecific biogeographical differentiation of Rhodnius pallescens (HEMIPTERA: REDUVIIDAE: RHODNIINI) from Colombia and Panama

Rhodnius pallescens is considered the main vector of Chagas disease in Panama and a relevant secondary vector in northern Colombia. Previous data reported that this species presents cytogenetically heterogeneous populations, which are probably biogeographically segregated. To provide new information on the diversity of R. pallescens, we compared several populations from Colombia and Panama based on the morphometric analyses of wings, mitochondrial cytochrome b (cyt b) gene sequencing, and genomic DNA measurements. Although no differences in DNA amount were detected, significant differences in cyt b sequences as well as wing size and shape were identified among populations. The results obtained in this work indicate R. pallescens comprises two evolutionary lineages with genetic and morphological differences that could be explained by their geographic isolation in distinct ecological zones. These results provide new insight into R. pallescens population diversity and the underlying biological processes that shape its evolution.

Environmental Determinants of the Distribution of Chagas Disease Vector Triatoma dimidiata in Colombia

Triatoma dimidiata (Hemiptera: Reduviidae) is a secondary vector of Trypanosoma cruzi in Colombia and represents an important epidemiological risk mainly in the central and oriental regions of the country where it occupies sylvatic, peridomestic, and intradomestic ecotopes, and because of this complex distribution, its distribution and abundance could be conditioned by environmental factors. In this work, we explored the relationship between T. dimidiata distribution and environmental factors in the northwest, northeast, and central zones of Colombia and developed predictive models of infestation in the country. The associations between the presence ofT. dimidiata and environmental variables were studied using logistic regression models and ecological niche modeling for a sample of villages in Colombia. The analysis was based on the information collected in field about the presence ofT. dimidiata and the environmental data for each village extracted from remote sensing images. The presence of Triatoma dimidiata(Latreille, 1811) was found to be significantly associated with the maximum vegetation index, minimum land surface temperature (LST), and the digital elevation for the statistical model. Temperature seasonality, annual precipitation, and vegetation index were the variables that most influenced the ecological niche model ofT. dimidiata distribution. The logistic regression model showed a good fit and predicted suitable habitats in the Andean and Caribbean regions, which agrees with the known distribution of the species, but predicted suitable habitats in the Pacific and Orinoco regions proposing new areas of research. Improved models to predict suitable habitats forT. dimidiata hold promise for spatial targeting of integrated vector management.