Tiago Belintani

Despite the epidemiological importance of triatomine bugs as vectors of Trypanosoma cruzi , mitogenomic resources remain limited for many lineages, restricting evolutionary and comparative analyses. The endemic Chilean genus Mepraia is a notable example, with scarce mitochondrial genomic information despite its relevance to Chagas disease ecology and vector evolution. Here, we reconstructed partial mitochondrial genomes, including all 13 protein-coding genes, from RNA-Seq data for three Mepraia species. Phylogenetic analyses confirmed the monophyly of Mepraia and resolved interspecific relationships, whereas comparative analyses revealed heterogeneous patterns of intraspecific diversity, with elevated variation in M. parapatrica . Codon-based tests detected pervasive purifying selection together with localized signals of positive selection in oxidative phosphorylation genes, particularly NAD5, NAD6, NAD1, and COIII. These results show that transcriptomic data provide a reliable source for mitochondrial genome reconstruction in non-model insects and that adaptive signals can coexist with strong functional constraint in triatomine mitogenomes. Overall, this study expands mitogenomic resources for Triatominae, improves evolutionary inference in Mepraia , and provides a foundation for future integrative studies on diversification, mitochondrial evolution, and vector biology.

Chagas disease, a significant global health concern rooted in social inequalities and political oversights, remains a challenging public health issue impacting millions worldwide. The increasing detection of triatomines, the vectors of Chagas disease, in urban areas complicates the situation.

Corrigendum: Transcriptome-based phylogenomic analysis reveals evidence of ancient hybridization events in the Mepraia genus (Hemiptera: Reduviidae: Triatominae)

Introduction: The Mepraia genus is composed of three endemic species in Chile, namely Mepraia spinolai, Mepraia gajardoi, and Mepraia parapatrica, all capable of transmitting the causative agent of Chagas disease. Although species divergence within this genus is supported by morphological, molecular, and geological evidence, it has never been validated by genome-wide data.Methods: In this sense, a pioneering phylogenomic study was conducted using transcriptome data of the three species, aiming to infer robust phylogenies and evaluate the impact of interspecific gene flow on the evolution of these insects. Our transcriptomes were used to robustly infer the phylogenetic relationships, employing multi-species coalescent and supermatrix approaches, as well as to investigate the occurrence of introgression.Results and discussion: The inferred phylogenies support the monophyly of the three described taxa and infer divergence times, although gene trees display high levels of discordance. Our results indicate widespread introgression among Mepraia lineages. Thus, our results support that Mepraia diversification occurred in a short period resulting in reticulate phylogenies and low genetic diversity. Additionally, we obtained evidence of introgression suggesting that ancient hybridization has had a major role in the evolution of the three Mepraia species.

Triatoma infestans is one of the main vectors of Chagas disease in Latin America. Although the species is under control in most Latin countries, it is still necessary to maintain epidemiological surveillance. The present study aims to characterize T. infestans populations from residual foci in Bahia and Rio Grande do Sul, Brazil, comparing them with natural populations in Argentina and Bolivia. For this, we adopt the geometric morphometry of the heads. It is possible to report the morphometric variety of the studied populations. In addition, we show that the size of the heads contributes to the differentiation between populations, while the shape has less power to discriminate groups. Furthermore, we show that some natural populations have morphometric proximity to residual populations, suggesting a relationship between these triatomines. Our data do not support the origin of residual populations but demonstrate the importance of new studies with other techniques to understand the dynamics of distribution and reintroduction of these vectors in Brazilian territory.

Background: Among the 18 genera of the Triatominae subfamily, three stand out for their diversity and epidemiological importance:Triatoma,Panstrongylus, andRhodnius.Rhodniusincludes 21 species that can transmitTrypanosoma cruzi(the etiological agent of Chagas disease, also known as American trypanosomiasis) andTrypanosoma rangeli. TheRhodnius prolixuscomplex comprises seven species, includingRhodnius marabaensis,Rhodnius prolixus, andRhodnius robustus, which occur in the northern region of Brazil. Since both adults and immatures can carryT. cruzi, in this study the five nymphal instars of the three species mentioned were dorsally characterized.Methods: Using microscopy, morphometrics, and geometric morphometrics, the present work measures and describes the morphological characters of the five nymphal instars ofR. marabaensis,R. prolixus, andR. robustus.Results: The study enabled the characterization of all five nymphal instars, as well as the distinction between the three species in each of their instars.Conclusions: The morphological, morphometrics of the head, thorax, and abdomen and geometric morphometrics studies of the head enabled the specific distinction of these three species in all five instars.Graphical

Trypanosoma cruzi presents great variability in morphology, virulence, pathogenicity, avoidance of the host immune system, and antigenic constitution, associated with different clinical manifestations of the disease. Two strains of T. cruzi were cultivated in liver infusion tryptose to determine growth kinetics, morphometry and molecular characterization using restriction fragment length polymorphism polymerase chain reaction. The biological parameters showed sharp growth by the 7^th day. Morphologically, both strains showed short and thin forms and were classified as Group I. Group TcI presents cardiac manifestations and T. sherlocki is adapting to the home environment, requiring attention to future problems.

Triatoma is the most diversified and one of the most important genera from an epidemiological perspective. Given the difficulty in identifying some species of the Triatoma genus, morphological, histological, and morphometric studies were performed to provide new characters that make it possible to differentiate T. garciabesi, T. guasayana, T. patagonica, and T. sordida sensu stricto, triatomines that overlap geographically and have vector potential. Through the external female genitalia, as well as morphology, morphometry, and histology of eggshells, it was possible to discriminate the four species. In addition, this study reinforces the taxonomic validity of T. garciabesi and provides new data for discussion on systematic issues of T. guasayana and T. patagonica.

Triatoma lenti and Triatoma sherlocki are endemic species of the State of Bahia, located in northeastern Brazil, where they have records of domiciliation in the human environment. In view of the epidemiological aspect and taxonomic importance of these species for the systematics of the Triatoma genus, a study was carried out with nymphs of all five instars. An extensive review of studies on nymphs from the subfamily Triatominae is presented. Morphology was studied using a scanning electron microscope and morphometric analyses. The morphological study allowed us to characterize and discriminate species by means of scanning electron microscope of the last abdominal segment. In addition, the results show morphometric variability, with the total size of the head that best discriminates the species. Studies on nymphs are fundamental to the ecosystem; however, the literature on the immature forms of certain groups is scarce, difficult to use, or nonexistent. Therefore, this study includes morphological and morphometric data of the nymphal instars of T. lenti and T. sherlocki, corroborating the specific taxonomy of these species.