First report of Triatoma sordida Stål, 1859 (Hemiptera, Reduviidae, Triatominae) in the State of Acre and Brazilian Western Amazon

Chagas Disease Vectors of Espírito Santo, Brazil: First Report of Triatoma infestans (Klug, 1834) (Hemiptera, Triatominae) in the Brazilian State and Development of an Identification Key Based on Cytogenetic Data

Chagas disease is a potentially life-threatening illness caused by the protozoan Trypanosoma cruzi and transmitted, mainly, by hematophagous insects of the Triatominae subfamily. In Brazil, there are currently about 66 triatomine species distributed throughout the country's 27 states. Triatoma infestans is considered as a species of great vectorial importance, mainly because of its biological characteristics, such as the high degree of anthropophilia, adaptation to the home environment, ability to withstand long periods of fasting, and present a wide geographical distribution. Taking into account the epidemiological importance of these species, we carried out the first report of T. infestans in the Espírito Santo, Brazil, and development of an identification key for all species notified in that state, based on cytogenetic data. This information is important because they contribute to the direction of epidemiological surveillance activities carried out by vector control programs of the Espírito Santo, Brazil.

Triatoma rosai sp. nov. (Hemiptera, Triatominae): A New Species of Argentinian Chagas Disease Vector Described Based on Integrative Taxonomy

Simple Summary

Although all triatomines are potential vectors of Chagas' disease, there are species with greater or lesser vectorial importance. Therefore, the correct identification of triatomines species is essential for the vector control programs. In general, triatomines are identified by external morphological characters. However, some species are very similar or even morphologically identical, being important the use of complementary analyses for the correct identification of species. For this reason, this study focused on the use of morphological, morphometric, molecular data, and experimental crosses to describe Triatoma rosai sp. nov., a new species of Argentinian Chagas disease vector. Significant morphological and morphometric differences, associated with phylogenetic support and high mortality rate of the hybrids made it possible to confirm the specific status of T. rosai sp. nov., emphasizing the importance of integrative analyses for the taxonomy of triatomines.

Abstract

Chagas disease is the most prevalent neglected tropical disease in the Americas and makes an important contribution to morbidity and mortality rates in countries where it is endemic since 30 to 40% of patients develop cardiac diseases, gastrointestinal disorders, or both. In this paper, a new species of the genus Triatoma is described based on specimens collected in the Department San Miguel, Province of Corrientes, Argentina. Triatoma rosai sp. nov. is closely related to T. sordida (Stål, 1859), and was characterized based on integrative taxonomy using morphological, morphometric, molecular data, and experimental crosses. These analyses, combined with data from the literature (cytogenetics, electrophoresis pattern, molecular analyses, cuticular hydrocarbons pattern, geometric morphometry, cycle, and average time of life as well as geographic distribution) confirm the specific status of T. rosai sp. nov. Natural Trypanosoma cruzi infection, coupled with its presence mostly in peridomestic habitats, indicates that this species can be considered as an important Chagas disease vector from Argentina.

Trypanosomes of vectors and domestic dogs in Trypanosoma cruzi transmission areas from Brazilian southwestern amazon: New mammalian host for Trypanosoma janseni

Trypanosoma cruzi is a widespread protozoan in Latin America causing Chagas disease in humans and able to infect several other mammal species. The objective of this study was to investigate the T. cruzi infection in triatomine fauna as well as in dogs from distinct areas of Acre, western Brazilian Amazonia, which recently reported acute cases of human CD as well as an area that have not notify this disease recently. Triatomines were collected and the intestinal contents were evaluated for the presence of trypanosomatids by optical microscopy and polymerase chain reaction (PCR) targeting the mini-exon gene. Blood smear, hemoculture, PCR and serology were performed in the studied mammals. Fecal content of four triatomines were positive (11.6%) in the fresh examination. Molecular analysis identified Trypanosoma cruzi TCI in two specimens. Blood samples from 90 dogs were obtained. Trypanosoma sp. was observed in six blood smears (6/83, 7.22%). Seropositivity for T. cruzi was 8/89 (8.98). One dog's hemoculture was obtained and characterized as T. rangeli. PCR reactions in blood clots resulted in one positive dog (1/75, 1.3%) infected by T. janseni, providing a new mammalian host for a recently described Trypanosoma species. The results demonstrate the low exposition and prevalence for T. cruzi suggesting that dogs are not important to T. cruzi transmission cycle in the studied áreas.

Revisiting the genetic variability of Brazilian peridomestic populations of the Chagas disease vector Triatoma sordida () (Hemiptera, Triatominae)

Triatoma sordida is an endemic species to South America, currently considered the species most frequently found in the peridomestic environment in Brazil. This triatomine has a wide ecological tolerability that allows it to inhabit several ecotopes and use different food sources. Although the species is considered predominantly peridomestic, it is also capable of colonizing households and forming numerous intra-household colonies, leading to its inclusion among the priorities for triatomine control campaigns in Brazil. All Brazilian populations of T. sordida are considered as T. sordida sensu stricto by chromosomal analyses (which highlights their epidemiological importance), although molecular studies that characterize the genetic diversity of these populations are scarce, being restricted only to the region of Minas Gerais. Thus, several populations of this vector distributed in the states of Bahia, Goiás, Mato Grosso do Sul, and Minas Gerais were analyzed using mitochondrial markers (cyt b and nd1). Low nucleotide diversity, high haplotypic diversity, low genetic distance, and high F_ST value were observed, as well as the formation of a monophyletic clade of the Brazilian populations of T. sordida, which confirms that this species has low genetic variability, with all specimens in Brazil grouped in T. sordida sensu stricto. In addition to the genetic and evolutionary importance for the knowledge of the biology of these vectors, these results are important from an epidemiological point of view, thus being able to direct vector control programs.

First report of Rhodnius montenegrensis (Hemiptera, Reduviidae, Triatominae) in Amazonas, Brazil

INTRODUCTION:

Triatomines are hematophagous insects of epidemiological importance because they are vectors of Chagas disease. We present here the first report of Rhodnius montenegrensis in Amazonas, Brazil.

METHODS:

Triatomines were collected from Attalea butyracea palm trees in the municipality of Guajará.

RESULTS:

Two adult female R. montenegrensis specimens were identified.

CONCLUSIONS:

The present study confirms that the number of triatomine species within the Amazon has increased from 10 to 11, and the number of Brazilian states with R. montenegrensis has increased from two to three.

Genetic Structure of Brazilian Populations of Triatoma sordida (Stål, 1859) (Hemiptera, Triatominae) by Means of Chromosomal Markers

Triatoma sordida is among the main Brazilian species considered as Chagas disease vectors. The genetic studies are directed mainly to phylogenetic questions because this species possibly have suffered cryptic speciation. Furthermore, there are few studies that analyzed the structure and genetic variability of specimens from Brazil and that showed low genetic diversity and strong genetic structuring of the population samples. Therefore, because of great epidemiological importance of T. sordida and mainly the restriction of genetic characterization of this vector only for populations of Minas Gerais state, this article performs a genetic analysis of the T. sordida from seven different Brazilian states (representing different biomes), by means of cytogenetic markers. All analyzed specimens presents the same cytogenetic characteristics: early meiotic prophase with several heterochromatic bodies dispersed in the nucleus (CG-rich), being one of them formed by the associated sex chromosomes surrounded by some autosomal heterochromatic regions, meiotic metaphase with most autosomal pairs exhibiting a C-heterochromatic block in one chromosomal end (CG-rich), Y sex chromosome fully heterochromatin (AT-rich), and X chromosome may present a small C-block (CG-rich). These results are important because the chromosomal markers enable to confirm and expand the low genetic diversity for all Brazilian states occupied by T. sordida, suggesting that all Brazilian populations were originated from a small ancestral population and possibly dispersed to other biomes by founder effect. In addition, we suggest that T. sordida from Brazil are not suffering cryptic speciation and we confirm the classification of all Brazilian examples as T. sordida sensu stricto.

Occurrence of triatomines (Hemiptera: Reduviidae) in domestic and natural environments in Novo Remanso, Itacoatiara, Amazonas, Brazil

INTRODUCTION

The present study reports the presence of triatomines in natural, peridomestic, and intradomicile environments in Itacoatiara municipality, state of Amazonas, a non-endemic region for Chagas disease.

METHODS

Active search was performed inside tree trunks, and palm trees, residences, and peridomiciles localized near the forest area.

RESULTS

Twenty adults and ten triatomines nymphs were collected, fifteen of which were from natural forests, thirteen from intradomiciles, and two from peridomicile areas.

CONCLUSIONS

The new records of adults and nymphs of triatomines in the intra- and peridomiciles suggest the adoption of prophylactic measures for vector surveillance in the study area.

First report of Panstrongylus lignarius (Walker, 1873) (Hemiptera: Reduviidae: Triatominae) in the State of Acre, Brazil

INTRODUCTION

This communication reports the first occurrence of Panstrongylus lignarius in the State of Acre, Brazil.

METHODS

A specimen of P. lignarius was collected from a residence in a rural area of the municipality of Rio Branco, Acre, Western Amazon.

RESULTS

This new report of P. lignarius extends the distribution of this species to eight Brazilian states, and also increases the number of species of Triatominae described from the state of Acre from nine to ten.

CONCLUSIONS

The occurrence of P. lignarius deserves attention, since this species has the potential for domiciliation and transmitting Trypanosoma cruzi.

First report of Panstrongylus megistus (Hemiptera, Reduviidae, Triatominae) in the State of Acre and Rondônia, Amazon, Brazil

INTRODUCTION

This article reports, for the first time, the occurrence of Panstrongylus megistus in the Brazilian Western Amazon.

METHODS

Specimens of P. megistus were collected in the cities of Rio Branco, Acre and Extrema, Rondônia.

RESULTS

The number of triatomine species in the State of Acre increased from eight to nine and in Rondônia from seven to eight. This was also the first report of P. megistus in the Brazilian Western Amazon.

CONCLUSION

The occurrence of P. megistus in the Western Amazon evidences an epidemiological alert, since it is an important vector of T. cruzi.

First report of Rhodnius neglectus (Hemiptera, Reduviidae, Triatominae) from the State of Acre, Brazil, and the Brazilian Western Amazon Region

INTRODUCTION

This communication reports the occurrence of Rhodnius neglectus in the State of Acre, Brazil.

METHODS

An adult male R. neglectus specimen was collected from the Catuaba Experimental Reserve, which is located in the municipality of Senador Guiomard.

RESULTS

This increases the number of triatomine species reported from the State of Acre to eight and is also the first report of R. neglectus from the Brazilian Western Amazon Region.

CONCLUSIONS

The occurrence of R. neglectus is alarming because even though the species is wild, it can invade and colonize human dwellings and peridomiciles, thereby increasing Chagas disease transmission.