Publications by authors named "Fernando A Monteiro"

26 Publications

  • Page 1 of 1

Under pressure: phenotypic divergence and convergence associated with microhabitat adaptations in Triatominae.

Parasit Vectors 2021 Apr 8;14(1):195. Epub 2021 Apr 8.

Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.

Background: Triatomine bugs, the vectors of Chagas disease, associate with vertebrate hosts in highly diverse ecotopes. It has been proposed that occupation of new microhabitats may trigger selection for distinct phenotypic variants in these blood-sucking bugs. Although understanding phenotypic variation is key to the study of adaptive evolution and central to phenotype-based taxonomy, the drivers of phenotypic change and diversity in triatomines remain poorly understood.

Methods/results: We combined a detailed phenotypic appraisal (including morphology and morphometrics) with mitochondrial cytb and nuclear ITS2 DNA sequence analyses to study Rhodnius ecuadoriensis populations from across the species' range. We found three major, naked-eye phenotypic variants. Southern-Andean bugs primarily from vertebrate-nest microhabitats (Ecuador/Peru) are typical, light-colored, small bugs with short heads/wings. Northern-Andean bugs from wet-forest palms (Ecuador) are dark, large bugs with long heads/wings. Finally, northern-lowland bugs primarily from dry-forest palms (Ecuador) are light-colored and medium-sized. Wing and (size-free) head shapes are similar across Ecuadorian populations, regardless of habitat or phenotype, but distinct in Peruvian bugs. Bayesian phylogenetic and multispecies-coalescent DNA sequence analyses strongly suggest that Ecuadorian and Peruvian populations are two independently evolving lineages, with little within-lineage phylogeographic structuring or differentiation.

Conclusions: We report sharp naked-eye phenotypic divergence of genetically similar Ecuadorian R. ecuadoriensis (nest-dwelling southern-Andean vs palm-dwelling northern bugs; and palm-dwelling Andean vs lowland), and sharp naked-eye phenotypic similarity of typical, yet genetically distinct, southern-Andean bugs primarily from vertebrate-nest (but not palm) microhabitats. This remarkable phenotypic diversity within a single nominal species likely stems from microhabitat adaptations possibly involving predator-driven selection (yielding substrate-matching camouflage coloration) and a shift from palm-crown to vertebrate-nest microhabitats (yielding smaller bodies and shorter and stouter heads). These findings shed new light on the origins of phenotypic diversity in triatomines, warn against excess reliance on phenotype-based triatomine-bug taxonomy, and confirm the Triatominae as an informative model system for the study of phenotypic change under ecological pressure .
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13071-021-04647-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8034103PMC
April 2021

Homology-Free Detection of Transposable Elements Unveils Their Dynamics in Three Ecologically Distinct Species.

Genes (Basel) 2020 02 6;11(2). Epub 2020 Feb 6.

UNESP-Univ. Estadual Paulista, Departamento de Biologia, São José do Rio Preto, SP 15054-000, Brazil.

Transposable elements (TEs) are widely distributed repetitive sequences in the genomes across the tree of life, and represent an important source of genetic variability. Their distribution among genomes is specific to each lineage. A phenomenon associated with this feature is the sudden expansion of one or several TE families, called bursts of transposition. We previously proposed that bursts of the family (DNA transposons) contributed to the speciation of Stål, 1859. This hypothesis motivated us to study two additional species of the complex: da Rosa et al., 2012 and Souza et al., 2016, together with a new, de novo annotation of the repeatome using unassembled short reads. Our analysis reveals that the total amount of TEs present in genomes (19% to 23.5%) is three to four times higher than that expected based on the original quantifications performed for the original genome description of . We confirm here that the repeatome of the three species is dominated by Class II elements of the superfamily as well as members of the LINE order (Class I). In addition to , we also identified a recent burst of transposition of the Mariner family in and , suggesting that this phenomenon may not be exclusive to . Rather, we hypothesize that whilst the expansion of elements may have contributed to the diversification of the - species complex, the distinct ecological characteristics of these new species did not drive the general evolutionary trajectories of these TEs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/genes11020170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7073582PMC
February 2020

Transcriptome-based molecular systematics: Rhodnius montenegrensis (Triatominae) and its position within the Rhodnius prolixus-Rhodnius robustus cryptic-species complex.

Parasit Vectors 2019 Jun 17;12(1):305. Epub 2019 Jun 17.

Grupo Triatomíneos, Instituto René Rachou, Fiocruz Minas Gerais, Fundação Oswaldo Cruz (Fiocruz), Belo Horizonte, Brazil.

Background: Rhodnius montenegrensis (Triatominae), a potential vector of Chagas disease, was described after R. robustus-like bugs from southwestern Amazonia. Mitochondrial cytb sequence near-identity with sympatric R. robustus (genotype II) raised doubts about the taxonomic status of R. montenegrensis, but comparative studies have reported fairly clear morphological and genetic differences between R. montenegrensis and laboratory stocks identified as R. robustus. Here, we use a transcriptome-based approach to investigate this apparent paradox.

Results: We retrieved publicly-available transcriptome sequence-reads from R. montenegrensis and from the R. robustus stocks used as the taxonomic benchmark in comparative studies. We (i) aligned transcriptome sequence-reads to mitochondrial (cytb) and nuclear (ITS2, D2-28S and AmpG) query sequences (47 overall) from members of the R. prolixus-R. robustus cryptic-species complex and related taxa; (ii) computed breadth- and depth-coverage for the 259 consensus sequences generated by these alignments; and, for each locus, (iii) appraised query sequences and full-breadth-coverage consensus sequences in terms of nucleotide-sequence polymorphism and phylogenetic relations. We found evidence confirming that R. montenegrensis and R. robustus genotype II are genetically indistinguishable and, hence, implying that they are, in all likelihood, the same species. Furthermore, we found compelling genetic evidence that the benchmark 'R. robustus' stocks used in R. montenegrensis description and in later transcriptome-based comparisons are in fact R. prolixus, although likely mixed to some degree with R. robustus (probably genotype II, a.k.a. R. montenegrensis).

Conclusions: We illustrate how public-domain genetic/transcriptomic data can help address challenging issues in disease-vector systematics. In our case-study, taxonomic confusion apparently stemmed from the misinterpretation of sequence-data analyses and misidentification of taxonomic-benchmark stocks. More generally, and together with previous reports of mixed and/or misidentified Rhodnius spp. laboratory colonies, our results call into question the conclusions of many studies (on morphology, genetics, physiology, behavior, bionomics or interactions with microorganisms including trypanosomes) based on non-genotyped 'R. prolixus' or 'R. robustus' stocks. Correct species identification is a prerequisite for investigating the factors that underlie the physiological, behavioral or ecological differences between primary domestic vectors of Chagas disease, such as R. prolixus, and their sylvatic, medically less-relevant relatives such as R. robustus (s.l.) including R. montenegrensis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13071-019-3558-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6580618PMC
June 2019

Phylogeography and demographic history of the Chagas disease vector Rhodnius nasutus (Hemiptera: Reduviidae) in the Brazilian Caatinga biome.

PLoS Negl Trop Dis 2018 09 24;12(9):e0006731. Epub 2018 Sep 24.

Laboratório de Epidemiologia e Sistemática Molecular, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.

Background: Rhodnius nasutus, a vector of the etiological agent Trypanosoma cruzi, is one of the epidemiologically most relevant triatomine species of the Brazilian Caatinga, where it often colonizes rural peridomestic structures such as chicken coops and occasionally invades houses. Historical colonization and determination of its genetic diversity and population structure may provide new information towards the improvement of vector control in the region. In this paper we present thoughtful analyses considering the phylogeography and demographic history of R. nasutus in the Caatinga.

Methodology/principal Findings: A total of 157 R. nasutus specimens were collected from Copernicia prunifera palm trees in eight geographic localities within the Brazilian Caatinga biome, sequenced for 595-bp fragment of the mitochondrial cytochrome b gene (cyt b) and genotyped for eight microsatellite loci. Sixteen haplotypes were detected in the cyt b sequences, two of which were shared among different localities. Molecular diversity indices exhibited low diversity levels and a haplotype network revealed low divergence among R. nasutus sequences, with two central haplotypes shared by five of the eight populations analyzed. The demographic model that better represented R. nasutus population dynamics was the exponential growth model. Results of the microsatellite data analyses indicated that the entire population is comprised of four highly differentiated groups, with no obvious contemporary geographic barriers that could explain the population substructure detected. A complex pattern of migration was observed, in which a western Caatinga population seems to be the source of emigrants to the eastern populations.

Conclusions/significance: R. nasutus that inhabit C. prunifera palms do not comprise a species complex. The species went through a population expansion at 12-10 ka, during the Holocene, which coincides with end of the largest dry season in South America. It colonized the Caatinga in a process that occurred from west to east in the region. R. nasutus is presently facing an important ecological impact caused by the continuous deforestation of C. prunifera palms in northeast Brazil. We hypothesize that this ecological disturbance might contribute to an increase in the events of invasion and colonization of human habitations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pntd.0006731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6195287PMC
September 2018

Field-collected Triatoma sordida from central Brazil display high microbiota diversity that varies with regard to developmental stage and intestinal segmentation.

PLoS Negl Trop Dis 2018 08 23;12(8):e0006709. Epub 2018 Aug 23.

Laboratório de Epidemiologia e Sistemática Molecular, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.

Background/methodology: Triatomine bugs are the vectors of Trypanosoma cruzi, the agent of Chagas disease. Vector control has for decades relied upon insecticide spraying, but insecticide resistance has recently emerged in several triatomine populations. One alternative strategy to reduce T. cruzi transmission is paratransgenesis, whereby symbiotic bacteria are genetically engineered to produce T. cruzi-killing proteins in the vector's gut. This approach requires in-depth knowledge of the vectors' natural gut microbiota. Here, we use metagenomics (16S rRNA 454 pyrosequencing) to describe the gut microbiota of field-caught Triatoma sordida-likely the most common peridomestic triatomine in Brazil. For large nymphs (4th and 5th stage) and adults, we also studied separately the three main digestive-tract segments-anterior midgut, posterior midgut, and hindgut.

Principal Findings: Bacteria of four phyla (12 genera) were present in both nymphs (all five stages) and adults, thus defining T. sordida's 'bacterial core': Actinobacteria (Brevibacterium, Corynebacterium, Dietzia, Gordonia, Nitriliruptor, Nocardia, Nocardiopsis, Rhodococcus, and Williamsia), Proteobacteria (Pseudomonas and Sphingobium), and Firmicutes (Staphylococcus). We found some clear differences in bacterial composition and relative abundance among development stages; overall, Firmicutes and Proteobacteria increased, but Actinobacteria decreased, through development. Finally, the bacterial microbiotas of the bugs' anterior midgut, posterior midgut, and hindgut were sharply distinct.

Conclusions/significance: Our results identify the 'bacterial core set' of T. sordida and reveal important gut microbiota differences among development stages-particularly between 1st-3rd stage nymphs and adults. Further, we show that, within any given development stage, the vectors' gut cannot be regarded as a single homogeneous environment. Cultivable, non-pathogenic 'core' bacterial species may now be tested as candidates for paratransgenic control of T. cruzi transmission by T. sordida.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pntd.0006709DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6138416PMC
August 2018

Spatial and Molecular Epidemiology of Giardia intestinalis Deep in the Amazon, Brazil.

PLoS One 2016 8;11(7):e0158805. Epub 2016 Jul 8.

Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.

Background: Current control policies for intestinal parasitosis focuses on soil-transmitted helminths, being ineffective against Giardia intestinalis, a highly prevalent protozoon that impacts children's nutritional status in developing countries. The objective of this study was to explore spatial and molecular epidemiology of Giardia intestinalis in children of Amerindian descent in the Brazilian Amazon.

Methodology/principal Findings: A cross sectional survey was performed in the Brazilian Amazon with 433 children aged 1 to 14 years. Fecal samples were processed through parasitological techniques and molecular characterization. Prevalence of G. intestinalis infection was 16.9% (73/433), reaching 22.2% (35/158) among children aged 2-5 years, and a wide distribution throughout the city with some hot spots. Positivity-rate was similar among children living in distinct socioeconomic strata (48/280 [17.1%] and 19/116 [16.4%] below and above the poverty line, respectively). Sequencing of the β-giardin gene revealed 52.2% (n = 12) of assemblage A and 47.8% (n = 11) of assemblage B with high haplotype diversity for the latter. The isolates clustered into two well-supported G. intestinalis clades. A total of 38 haplotypes were obtained, with the following subassemblages distribution: 5.3% (n = 2) AII, 26.3% (n = 10) AIII, 7.9% (n = 3) BIII, and 60.5% (n = 23) new B genotypes not previously described.

Conclusions/significance: Giardia intestinalis infection presents a high prevalence rate among Amerindian descended children living in Santa Isabel do Rio Negro/Amazon. The wide distribution observed in a small city suggests the presence of multiple sources of infection, which could be related to environmental contamination with feces, possibly of human and animal origin, highlighting the need of improving sanitation, safe water supply and access to diagnosis and adequate treatment of infections.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0158805PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4938420PMC
July 2017

Rhodnius prolixus and R. robustus (Hemiptera: Reduviidae) nymphs show different locomotor patterns on an automated recording system.

Parasit Vectors 2016 Apr 27;9:239. Epub 2016 Apr 27.

Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil.

Background: Circadian rhythms of triatomines, vectors of the etiological agent Trypanosoma cruzi responsible for Chagas disease, have been extensively studied in adults of the two most epidemiologically relevant vector species, Rhodnius prolixus and Triatoma infestans. However, little attention has been dedicated to the activity patterns in earlier developmental stages, even though triatomine nymphs are equally capable of transmitting T. cruzi to humans. Because circadian rhythms may differ even between closely related species, studies that focus on this behavioral trait can also be used to shed light on the taxonomy of controversial taxa, which becomes especially relevant regarding vector species.

Methods: We compared the daily locomotor activity patterns of second- and third-instar nymphs of Rhodnius prolixus and Rhodnius robustus in order to unveil possible behavioral differences between these cryptic species. Mitochondrial and nuclear markers were sequenced to confirm species identification.

Results: Nymphs of both species had a bimodal pattern of locomotion and similar daily activity patterns, but R. prolixus is more active under light/dark cycles and depicts a more pronounced activity rhythm under constant darkness conditions.

Conclusions: We describe the implementation of an often-used automated method for the recording of individual locomotor activity to differentiate sibling species of Rhodnius with distinct epidemiological relevance. The higher levels of activity observed in the nymphs of R. prolixus could potentially contribute to increased vector capacity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13071-016-1482-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4848847PMC
April 2016

Marking Triatoma brasiliensis, Triatoma pseudomaculata and Rhodnius nasutus Nymphs with Trace Elements: Element Persistence and Effects of Marking on Insect Mortality.

PLoS Negl Trop Dis 2016 Mar 30;10(3):e0004548. Epub 2016 Mar 30.

Laboratório de Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.

Background: Field ecologists often rely on mark-release-recapture (MRR) experiments to estimate population dynamics parameters for a given species. In the case of a medically important taxon, i.e., a disease vector, inferences on species survival and dispersal rates are particularly important as they have the potential to provide insights into disease transmission dynamics in endemic areas. Medical entomologists have traditionally used fluorescent dusts to externally mark the cuticle of insects. However, dust marking is usually restricted to the adult life stage because immature insects lose the mark when they molt.

Methodology/principal Findings: We evaluated the efficacy of 13 trace elements in marking nymphs of three native Brazilian Chagas disease vectors: Triatoma brasiliensis, Triatoma pseudomaculata, and Rhodnius nasutus. Cr and Cu were detected in over 97% of T. brasiliensis (34/35 31/31 for Cr and Cu), while Cu and Mn were detected in more than 95% of T. pseudomaculata (29/29 for Cu and 28/29 for Mn) tested 120 days after marking. Only Mn marked over 90% of R. nasutus nymphs (38/41). Overall, trace elements had no negative effects on T. pseudomaculata longevity, but As-marked T. brasiliensis nymphs (p<0.01), and Cd-marked R. nasutus nymphs (p<0.01) had significantly shorter lifespan.

Conclusions/significance: Previous evidence shows that there is little or no genetic differentiation between populations at the microgeographic level, which often precludes indirect estimations of dispersal capability based on genetic markers. In such situations, MRR studies are more suitable as they measure insect movement directly from one site to another, instead of effective migration (i.e. gene flow). The determination of a reliable and persistent marking method is the first step towards the development of meaningful ecological estimates through the application of MRR methodology. Here, we have identified trace elements that can be used for mark and recapture studies of three triatomine species in Brazil.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pntd.0004548DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4814127PMC
March 2016

Trypanosoma cruzi-infected Panstrongylus geniculatus and Rhodnius robustus adults invade households in the Tropics of Cochabamba region of Bolivia.

Parasit Vectors 2016 Mar 16;9:158. Epub 2016 Mar 16.

Laboratório de Epidemiologia e Sistemática Molecular, Instituto Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil.

Background: There are hardly any data available on the relationships between the parasite and the vector or regarding potential reservoirs involved in the natural transmission cycle of Trypanosoma cruzi in the Tropics of Cochabamba, Bolivia. Local families from communities were responsible for the capture of triatomine specimens, following a strategic methodology based on entomological surveillance with community participation developed by the National Chagas Programme of the Ministry of Health of Bolivia.

Findings: We describe the collection of adult Panstrongylus geniculatus and Rhodnius robustus naturally infected with Trypanosoma cruzi from houses and from the hospital of Villa Tunari municipality. The flagellates found in the digestive tract of P. geniculatus belong to genetic lineages or DTUs TcI and TcIII, whereas only lineage DTU TcI was found in R. robustus. The detection of these vectors infected with T. cruzi reveals the vulnerability of local communities.

Conclusion: The results presented here highlight the risk of Chagas disease transmission in a region previously thought not to be endemic, indicating that the Tropics of Cochabamba should be placed under permanent entomological and epidemiological surveillance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13071-016-1445-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4794895PMC
March 2016

Genome of Rhodnius prolixus, an insect vector of Chagas disease, reveals unique adaptations to hematophagy and parasite infection.

Proc Natl Acad Sci U S A 2015 Dec 16;112(48):14936-41. Epub 2015 Nov 16.

Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-591, Brazil;

Rhodnius prolixus not only has served as a model organism for the study of insect physiology, but also is a major vector of Chagas disease, an illness that affects approximately seven million people worldwide. We sequenced the genome of R. prolixus, generated assembled sequences covering 95% of the genome (∼ 702 Mb), including 15,456 putative protein-coding genes, and completed comprehensive genomic analyses of this obligate blood-feeding insect. Although immune-deficiency (IMD)-mediated immune responses were observed, R. prolixus putatively lacks key components of the IMD pathway, suggesting a reorganization of the canonical immune signaling network. Although both Toll and IMD effectors controlled intestinal microbiota, neither affected Trypanosoma cruzi, the causal agent of Chagas disease, implying the existence of evasion or tolerance mechanisms. R. prolixus has experienced an extensive loss of selenoprotein genes, with its repertoire reduced to only two proteins, one of which is a selenocysteine-based glutathione peroxidase, the first found in insects. The genome contained actively transcribed, horizontally transferred genes from Wolbachia sp., which showed evidence of codon use evolution toward the insect use pattern. Comparative protein analyses revealed many lineage-specific expansions and putative gene absences in R. prolixus, including tandem expansions of genes related to chemoreception, feeding, and digestion that possibly contributed to the evolution of a blood-feeding lifestyle. The genome assembly and these associated analyses provide critical information on the physiology and evolution of this important vector species and should be instrumental for the development of innovative disease control methods.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1506226112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4672799PMC
December 2015

On palms, bugs, and Chagas disease in the Americas.

Acta Trop 2015 Nov 18;151:126-41. Epub 2015 Jul 18.

Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.

Palms are ubiquitous across Neotropical landscapes, from pristine forests or savannahs to large cities. Although palms provide useful ecosystem services, they also offer suitable habitat for triatomines and for Trypanosoma cruzi mammalian hosts. Wild triatomines often invade houses by flying from nearby palms, potentially leading to new cases of human Chagas disease. Understanding and predicting triatomine-palm associations and palm infestation probabilities is important for enhancing Chagas disease prevention in areas where palm-associated vectors transmit T. cruzi. We present a comprehensive overview of palm infestation by triatomines in the Americas, combining a thorough reanalysis of our published and unpublished records with an in-depth review of the literature. We use site-occupancy modeling (SOM) to examine infestation in 3590 palms sampled with non-destructive methods, and standard statistics to describe and compare infestation in 2940 palms sampled by felling-and-dissection. Thirty-eight palm species (18 genera) have been reported to be infested by ∼39 triatomine species (10 genera) from the USA to Argentina. Overall infestation varied from 49.1-55.3% (SOM) to 62.6-66.1% (dissection), with important heterogeneities among sub-regions and particularly among palm species. Large palms with complex crowns (e.g., Attalea butyracea, Acrocomia aculeata) and some medium-crowned palms (e.g., Copernicia, Butia) are often infested; in slender, small-crowned palms (e.g., Euterpe) triatomines associate with vertebrate nests. Palm infestation tends to be higher in rural settings, but urban palms can also be infested. Most Rhodnius species are probably true palm specialists, whereas Psammolestes, Eratyrus, Cavernicola, Panstrongylus, Triatoma, Alberprosenia, and some Bolboderini seem to use palms opportunistically. Palms provide extensive habitat for enzootic T. cruzi cycles and a critical link between wild cycles and transmission to humans. Unless effective means to reduce contact between people and palm-living triatomines are devised, palms will contribute to maintaining long-term and widespread, albeit possibly low-intensity, transmission of human Chagas disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.actatropica.2015.07.005DOI Listing
November 2015

Genetic diversity of Brazilian Aedes aegypti: patterns following an eradication program.

PLoS Negl Trop Dis 2014 Sep 18;8(9):e3167. Epub 2014 Sep 18.

Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, United States of America.

Background: Aedes aegypti is the most important vector of dengue fever in Brazil, where severe epidemics have recently taken place. Ae. aegypti in Brazil was the subject of an intense eradication program in the 1940s and 50s to control yellow fever. Brazil was the largest country declared free of this mosquito by the Pan-American Health Organization in 1958. Soon after relaxation of this program, Ae. aegypti reappeared in this country, and by the early 1980s dengue fever had been reported. The aim of this study is to analyze the present-day genetic patterns of Ae. aegypti populations in Brazil.

Methodology/principal Findings: We studied the genetic variation in samples of 11 widely spread populations of Ae. aegypti in Brazil based on 12 well-established microsatellite loci. Our principal finding is that present-day Brazilian Ae. aegypti populations form two distinct groups, one in the northwest and one in the southeast of the country. These two groups have genetic affinities to northern South American countries and the Caribbean, respectively. This is consistent with what has been reported for other genetic markers such as mitochondrial DNA and allele frequencies at the insecticide resistance gene, kdr.

Conclusions/significance: We conclude that the genetic patterns in present day populations of Ae. aegypti in Brazil are more consistent with a complete eradication of the species in the recent past followed by re-colonization, rather than the alternative possibility of expansion from residual pockets of refugia. At least two colonizations are likely to have taken place, one from northern South American countries (e.g., Venezuela) that founded the northwestern group, and one from the Caribbean that founded the southeastern group. The proposed source areas were never declared free of Ae. aegypti.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pntd.0003167DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169244PMC
September 2014

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

Mem Inst Oswaldo Cruz 2013 ;108 Suppl 1:92-9

Laboratório de Epidemiologia e Sistemática Molecular, Laboratório de Epidemiologia e Sistemática Molecular.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1590/0074-0276130434DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4109185PMC
December 2014

Phylogeographic pattern and extensive mitochondrial DNA divergence disclose a species complex within the Chagas disease vector Triatoma dimidiata.

PLoS One 2013 5;8(8):e70974. Epub 2013 Aug 5.

Laboratório de Epidemiologia e Sistemática Molecular, Instituto Oswaldo Cruz - Fiocruz, Rio de Janeiro, Brazil.

Background: Triatoma dimidiata is among the main vectors of Chagas disease in Latin America. However, and despite important advances, there is no consensus about the taxonomic status of phenotypically divergent T. dimidiata populations, which in most recent papers are regarded as subspecies.

Methodology And Findings: A total of 126 cyt b sequences (621 bp long) were produced for specimens from across the species range. Forty-seven selected specimens representing the main cyt b clades observed (after a preliminary phylogenetic analysis) were also sequenced for an ND4 fragment (554 bp long) and concatenated with their respective cyt b sequences to produce a combined data set totalling 1175 bp/individual. Bayesian and Maximum-Likelihood phylogenetic analyses of both data sets (cyt b, and cyt b+ND4) disclosed four strongly divergent (all pairwise Kimura 2-parameter distances >0.08), monophyletic groups: Group I occurs from Southern Mexico through Central America into Colombia, with Ecuadorian specimens resembling Nicaraguan material; Group II includes samples from Western-Southwestern Mexico; Group III comprises specimens from the Yucatán peninsula; and Group IV consists of sylvatic samples from Belize. The closely-related, yet formally recognized species T. hegneri from the island of Cozumel falls within the divergence range of the T. dimidiata populations studied.

Conclusions: We propose that Groups I-IV, as well as T. hegneri, should be regarded as separate species. In the Petén of Guatemala, representatives of Groups I, II, and III occur in sympatry; the absence of haplotypes with intermediate genetic distances, as shown by multimodal mismatch distribution plots, clearly indicates that reproductive barriers actively promote within-group cohesion. Some sylvatic specimens from Belize belong to a different species - likely the basal lineage of the T. dimidiata complex, originated ~8.25 Mya. The evidence presented here strongly supports the proposition that T. dimidiata is a complex of five cryptic species (Groups I-IV plus T. hegneri) that play different roles as vectors of Chagas disease in the region.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0070974PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3733668PMC
March 2014

A nuclear single-nucleotide polymorphism (SNP) potentially useful for the separation of Rhodnius prolixus from members of the Rhodnius robustus cryptic species complex (Hemiptera: Reduviidae).

Infect Genet Evol 2013 Mar 6;14:426-33. Epub 2012 Dec 6.

Laboratório de Sistemáticae Bioquímica, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil.

The design and application of rational strategies that rely on accurate species identification are pivotal for effective vector control. When morphological identification of the target vector species is impractical, the use of molecular markers is required. Here we describe a non-coding, single-copy nuclear DNA fragment that contains a single-nucleotide polymorphism (SNP) with the potential to distinguish the important domestic Chagas disease vector, Rhodnius prolixus, from members of the four sylvatic Rhodnius robustus cryptic species complex. A total of 96 primer pairs obtained from whole genome shotgun sequencing of the R. prolixus genome (12,626 random reads) were tested on 43 R. prolixus and R. robustus s.l. samples. One of the seven amplicons selected (AmpG) presented a SNP, potentially diagnostic for R. prolixus, on the 280th site. The diagnostic nature of this SNP was then confirmed based on the analysis of 154 R. prolixus and R. robustus s.l. samples representing the widest possible geographic coverage. The results of a 60% majority-rule Bayesian consensus tree and a median-joining network constructed based on the genetic variability observed reveal the paraphyletic nature of the R. robustus species complex, with respect to R. prolixus. The AmpG region is located in the fourth intron of the Transmembrane protein 165 gene, which seems to be in the R. prolixus X chromosome. Other possible chromosomal locations of the AmpG region in the R. prolixus genome are also presented and discussed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.meegid.2012.10.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3883588PMC
March 2013

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

Infect Genet Evol 2012 Dec 24;12(8):1975-83. Epub 2012 May 24.

Grupo de Biología y Control de Enfermedades Infecciosas - BCEI, Sede de Investigación Universitaria - SIU, Instituto de Biología, Universidad de Antioquia, Medellín, Colombia.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.meegid.2012.04.003DOI Listing
December 2012

Very low levels of genetic variation in natural peridomestic populations of the Chagas disease vector Triatoma sordida (Hemiptera: Reduviidae) in southeastern Brazil.

Am J Trop Med Hyg 2009 Aug;81(2):223-7

Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.

Levels of genetic variation and population structure were determined for 181 Triatoma sordida insects from four populations of southeastern Brazil, through the analysis of 28 allozyme loci. None of these loci presented fixed differences between any pair of populations, and only two revealed polymorphism, accounting for low levels of heterozygosity (H(e) = 0.027), and low genetic distances (D < 0.03) among populations. F(ST) and Contingency Table results indicated the existence of genetic structure among populations (F(ST) = 0.214), which were incompatible with the isolation by distance model (Mantel test: r = 0.774; P = 0.249).
View Article and Find Full Text PDF

Download full-text PDF

Source
August 2009

Ecology, evolution, and the long-term surveillance of vector-borne Chagas disease: a multi-scale appraisal of the tribe Rhodniini (Triatominae).

Acta Trop 2009 May-Jun;110(2-3):159-77. Epub 2008 Jun 21.

Instituto Leônidas e Maria Deane - Fiocruz Amazônia, Manaus, Amazonas, Brazil.

Chagas disease incidence has sharply declined over the last decade. Long-term disease control will, however, require extensive, longitudinal surveillance systems capable of detecting (and dealing with) reinvasion-reinfestation of insecticide-treated dwellings by non-domiciliated triatomines. Sound surveillance design calls for reliable data on vector ecology, and these data must cover different spatial scales. We conducted a multi-scale assessment of ecological and evolutionary trends in members of the tribe Rhodniini, including (i) a macroscale analysis of Rhodniini species richness and composition patterns across the Americas, and (ii) a detailed, mesoscale case-study of ecological and behavioural trends in Rhodnius neglectus and R. nasutus. Our macroscale overview provides some comprehensive insights about key mechanisms/processes probably underlying ecological and genetic diversification in the Rhodniini. These insights translate into a series of testable hypotheses about current species distributions and their likely causes. At the landscape scale, we used geometric morphometrics to identify dubious specimens as either R. neglectus or R. nasutus (two near-sibling species), and studied palm tree populations of these two vector taxa in five geographical areas. The data suggest that deforestation and the associated loss of habitat and host diversity might increase the frequency of vector-human contact (and perhaps Trypanosoma cruzi infection rates in vectors). Surveillance in central-northeastern Brazil should prioritise deforested landscapes where large palm trees (e.g., Attalea, Mauritia, Copernicia, Acrocomia or Syagrus) occur near houses. We anticipate that, by helping define the distribution patterns and ecological preferences of each species, multi-scale research will significantly strengthen vector surveillance systems across Latin America.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.actatropica.2008.06.005DOI Listing
May 2009

Molecular genetics reveal that silvatic Rhodnius prolixus do colonise rural houses.

PLoS Negl Trop Dis 2008 Apr 2;2(4):e210. Epub 2008 Apr 2.

Pathogen Molecular Biology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.

Background: Rhodnius prolixus is the main vector of Chagas disease in Venezuela. Here, domestic infestations of poor quality rural housing have persisted despite four decades of vector control. This is in contrast to the Southern Cone region of South America, where the main vector, Triatoma infestans, has been eliminated over large areas. The repeated colonisation of houses by silvatic populations of R. prolixus potentially explains the control difficulties. However, controversy surrounds the existence of silvatic R. prolixus: it has been suggested that all silvatic populations are in fact Rhodnius robustus, a related species of minor epidemiological importance. Here we investigate, by direct sequencing (mtcytb, D2) and by microsatellite analysis, 1) the identity of silvatic Rhodnius and 2) whether silvatic populations of Rhodnius are isolated from domestic populations.

Methods And Findings: Direct sequencing confirmed the presence of R. prolixus in palms and that silvatic bugs can colonise houses, with house and palm specimens sharing seven cytb haplotypes. Additionally, mitochondrial introgression was detected between R. robustus and R. prolixus, indicating a previous hybridisation event. The use of ten polymorphic microsatellite loci revealed a lack of genetic structure between silvatic and domestic ecotopes (non-significant F(ST) values), which is indicative of unrestricted gene flow.

Conclusions: Our analyses demonstrate that silvatic R. prolixus presents an unquestionable threat to the control of Chagas disease in Venezuela. The design of improved control strategies is essential for successful long term control and could include modified spraying and surveillance practices, together with housing improvements.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pntd.0000210DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2270345PMC
April 2008

Biogeography and evolution of Amazonian triatomines (Heteroptera: Reduviidae): implications for Chagas disease surveillance in humid forest ecoregions.

Mem Inst Oswaldo Cruz 2007 Oct 5;102 Suppl 1:57-70. Epub 2007 Nov 5.

Instituto Leonidas & Maria Deane-Fiocruz, Amazônia, Rua Teresina, Manaus, AM, Brasil.

An ecological-evolutionary classification of Amazonian triatomines is proposed based on a revision of their main contemporary biogeographical patterns. Truly Amazonian triatomines include the Rhodniini, the Cavernicolini, and perhaps Eratyrus and some Bolboderini. The tribe Rhodniini comprises two major lineages (pictipes and robustus). The former gave rise to trans-Andean (pallescens) and Amazonian (pictipes) species groups, while the latter diversified within Amazonia (robustus group) and radiated to neighbouring ecoregions (Orinoco, Cerrado-Caatinga-Chaco, and Atlantic Forest). Three widely distributed Panstrongylus species probably occupied Amazonia secondarily, while a few Triatoma species include Amazonian populations that occur only in the fringes of the region. T. maculata probably represents a vicariant subset isolated from its parental lineage in the Caatinga-Cerrado system when moist forests closed a dry trans-Amazonian corridor. These diverse Amazonian triatomines display different degrees of synanthropism, defining a behavioural gradient from household invasion by adult triatomines to the stable colonisation of artificial structures. Anthropogenic ecological disturbance (driven by deforestation) is probably crucial in the onset of the process, but the fact that only a small fraction of species effectively colonises artificial environments suggests a role for evolution at the end of the gradient. Domestic infestation foci are restricted to drier subregions within Amazonia; thus, populations adapted to extremely humid rainforest microclimates may have limited chances of successfully colonising the slightly drier artificial microenvironments. These observations suggest several research avenues, from the use of climate data to map risk areas to the assessment of the synanthropic potential of individual vector species.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1590/s0074-02762007005000108DOI Listing
October 2007

Molecular research and the control of Chagas disease vectors.

An Acad Bras Cienc 2005 Sep 24;77(3):437-54. Epub 2005 Aug 24.

Coordenação de Biodiversidade em Saúde, Centro de Pesquisa Leônidas e Maria Deane Fiocruz-Amazônia, Manaus, AM 69057-070, Brasil.

Chagas disease control initiatives are yielding promising results. Molecular research has helped successful programs by identifying and characterizing introduced vector populations and by defining intervention targets accurately. However, researchers and health officials are facing new challenges throughout Latin America. Native vectors persistently reinfest insecticide-treated households, and sylvatic triatomines maintain disease transmission in humid forest regions (including Amazonia) without colonizing human dwellings. In these scenarios, fine-scale vector studies are essential to define epidemiological risk patterns and clarify the involvement of little-known triatomine taxa in disease transmission. These eco-epidemiological investigations, as well as the planning and monitoring of control interventions, rely by necessity on accurate taxonomic judgments. The problems of cryptic speciation and phenotypic plasticity illustrate this need--and how molecular systematics can provide the fitting answers. Molecular data analyses also illuminate basic aspects of vector evolution and adaptive trends. Here we review the applications of molecular markers (concentrating on allozymes and DNA sequencing) to the study of triatomines. We analyze the suitability, strengths and weaknesses of the various techniques for taxonomic, systematic and evolutionary investigations at different levels (populations, species, and higher taxonomic categories).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1590/s0001-37652005000300007DOI Listing
September 2005

Can wild Triatoma infestans foci in Bolivia jeopardize Chagas disease control efforts?

Trends Parasitol 2005 Jan;21(1):7-10

Departamento de Entomologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av. Brazil.

The expected success of Chagas disease control programs in the Southern Cone countries relied on the assumption that Triatoma infestans, the main domestic vector, did not maintain silvatic foci except in the Cochabamba valley in Bolivia. Recent fieldwork revealed that wild populations of this vector are much more widespread throughout Bolivia than previously thought. Therefore, it is important to find out whether these silvatic populations could jeopardize control efforts in Bolivia, and to investigate their possible occurrence in neighboring regions of Paraguay and Argentina.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.pt.2004.10.007DOI Listing
January 2005

Nested clade and phylogeographic analyses of the Chagas disease vector Triatoma brasiliensis in Northeast Brazil.

Mol Phylogenet Evol 2004 Jul;32(1):46-56

Departamento de Medicina Tropical, Instituto Oswaldo Cruz-Fiocruz, Av. Brasil 4365, Rio de Janeiro, RJ 21045-900, Brazil.

Triatoma brasiliensis (Hemiptera: Reduviidae: Triatominae) is the most important Chagas disease vector in the semiarid areas of Northeast Brazil. We analyzed mitochondrial cytochrome b sequence variation among 136 individuals representing 16 populations from across the species' distribution. Neighbor-joining and parsimony tree-building methods were used in conjunction with nested clade analysis to describe the systematics and phylogeography of this species. Our results indicate that T. brasiliensis is composed of four genetically distinct chromatic forms (referred to as brasiliensis, macromelasoma, juazeiro, and melanica) that present inter-population divergence values (0.027-0.119, corrected K2-p) and a pattern of haplotype geographic distribution compatible with the existence of a species complex. As a consequence, such forms can be treated as isolated targets in vector control programs. We were unable to infer what is shaping the population structure of the brasiliensis form as we obtained mutually exclusive causes of structure, namely a barrier to gene flow caused by past population fragmentation, and isolation by distance between populations (which would permit gene flow). We found indication of mitochondrial DNA introgression occurring among forms in putative hybrid zones.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ympev.2003.12.011DOI Listing
July 2004

Molecular phylogeography of the Amazonian Chagas disease vectors Rhodnius prolixus and R. robustus.

Mol Ecol 2003 Apr;12(4):997-1006

Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, USA.

The phylogeographical structure of the closely related species Rhodnius prolixus and R. robustus is presented based on a 663-base pair (bp) fragment of the mitochondrial cytochrome b gene. Twenty haplotypes were recovered from 84 samples examined, representing 26 populations from seven Latin American countries. The resulting phylogenetic tree is composed of five major reciprocally monophyletic clades, one representing R. prolixus and four representing R. robustus. While R. prolixus is a very homogeneous assemblage, R. robustus has deeper clades and is paraphyletic, with the clade comprising R. robustus from Venezuela (Orinoco region) more closely related to the R. prolixus clade than to the other R. robustus populations from the Amazon region. The R. robustus paraphyly was supported further by the analysis of a nuclear gene (D2 region of the 28S RNA) for a subset of specimens. The data support the view that R. robustus represents a species complex. Levels of sequence divergence between clades within each region are compatible with a Pleistocene origin. Nucleotide diversity (pi) for all R. prolixus populations was extremely low (0.0008), suggesting that this species went through a recent bottleneck, and was subsequently dispersed by man.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1046/j.1365-294x.2003.01802.xDOI Listing
April 2003