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Background A new triatomine species was discovered in the semiarid Caatinga region of Rio Grande do Norte, Brazil, where it coexists with Triatoma brasiliensis in both natural and artificial habitats. Methods Triatomine specimens were captured in peridomestic and sylvatic environments in Rio Grande do Norte. Their identification was based on a combination of analyses, including morphology using dichotomous keys, head and hemelytron morphometry, and phylogeny using cytochrome b and internal transcribed spacer markers. Results The new species exhibits morphological traits that are intermediate between those of Triatoma brasiliensis and Triatoma petrocchiae , but has distinct characteristics, leading to its designation as Triatoma chiarii sp. nov. Geometric morphometric analysis of its wings and head clearly distinguished T. chiarii sp. nov. from T. brasiliensis and T. petrocchiae , while phylogenetic reconstruction confirmed its placement within the T. brasiliensis species complex. Both approaches consistently supported T. chiarii sp. nov. as a species closely related to T. petrocchiae , but with sufficient phenotypic and genotypic divergence to warrant its recognition as a new taxonomic entity. Conclusions Since T. chiarii sp. nov. was also found in the peridomestic environment, its possible role in the eco-epidemiology of Chagas disease warrants further investigation.

The Triatominae are of relevant public health importance because they include hematophagous species which are proven or potential vectors of Chagas disease. Currently, eighteen genera are considered valid in this subfamily. Through a comprehensive and integrative study, the description of a new genus of Triatomine, the nineteenth of the subfamily, is presented. Were generated a robust phylogeny from data deposited in Genbank, created a table comparing two genera with Hospesneotomae , and prepared a dichotomous key for the genus and species. To this end, several systematic pieces of evidence about this group were taken into consideration, such as morphology, genetics, ecotopes and species distribution. The new genus is proposed to include the species previously included in the T. protracta complex, considered now in a new taxonomic assignment. Therefore, Hospesneotomae n. gen. will be composed by the following seven species (in the new combination): H. protracta , H. barberi , H. incrassata, H. peninsularis, H. sinaloensis, H. neotomae and H. nitida , providing an innovative perspective in understanding these organisms, because the seven species grouped here in the proposed new genus are distinct from the others species of Triatoma and at the same time show similarities that indicates that they form a monophyletic group.

The transmission dynamics of Trypanosoma cruzi in natural environments exhibit considerable variation at the micro-locality scale. However, the specific biotic and abiotic factors driving this heterogeneity remain largely unidentified. The Atlantic Forest of the state of Espírito Santo (ES) presents a unique transmission network of T. cruzi , in which Triatoma vitticeps represents the absolute majority among existing triatomines, with high infection rates and diversity of genotypes, frequently invading homes. No infection was found in peridomestic mammals. This study aimed to elucidate the spatial and environmental distribution patterns of T. vitticeps and its infection by T. cruzi DTUs throughout Espírito Santo, quantifying the influence of abiotic variables on both vector occurrence and infection dynamics. Species Distribution Modeling (SDM) of T. cruzi genotypes in T. vitticeps collected in the Atlantic Forest of Espírito Santo was performed using the ModleR package, in the R programming language, with climate and landscape variables (~1km²) selected by Spearman’s correlation [-0.7 ≤ ρ ≤ 0.7]. True Skill Statistic (≥ 0.7) was used to evaluate model performance. Decision tree to classify T. vitticeps infection by T. cruzi was created using machine learning algorithms in WEKA 3.8.6 software. The SDMs of T. vitticeps and its infection demonstrated: i. Central and South mesoregions presented better environmental conditions for their occurrence; ii. association with mountainous regions with high altitudes, humid and superhumid, with vegetation density and vigor and high values of topographic diversity; iii. Schoener similarity suggests Z3 is mixed, dominated by TcIV and TcIII in Central–South, with TcIII influence Northwest and North Coast; iv. Infection was explained by wind speed, mammal richness, and temperature, with the decision tree identifying 84% of positives and 29% of negatives. T. vitticeps may originate in high-altitude regions and disperse via wind to lowlands, promoting domiciliary invasion and supporting previously hypothesized long-distance transmission of T. cruzi .

Background Triatoma brasiliensis brasiliensis is the primary vector of Chagas disease in Brazil's semi-arid regions, exhibiting adaptability to various environments, including domestic and peridomestic. Despite its significance, comprehensive genomic data for this subspecies remain limited. Methods We assembled the complete mitochondrial genome of T. b. brasiliensis using a combination of Illumina and Sanger sequencing technologies, the latter being necessary to obtain the control region with eight primers designed in this study. The mitogenome was annotated to identify gene content and organization. Phylogenetic relationships were inferred using conserved blocks of 13 protein-coding genes and 22 transfer RNA genes. For this analysis, 18 representative triatomines with near-complete mitogenomes were selected, and phylogenetic reconstruction was performed using the maximum ikelihood method. Results The complete mitogenome spans 16,575 base pairs and includes 13 protein-coding genes, 22 transfer RNA genes, and two ribosomal RNA genes, consistent with the typical structure of insect mitochondrial genomes. The control region exhibited tandem and inverted repeats arranged in blocks, as observed for other Reduviidae. Given the limited availability of mitogenomes, our phylogenetic analysis provided statistical support for T. b. brasiliensis as a sister taxon to Triatoma infestans , forming a well-supported clade that is sister to Triatoma vitticeps . Conclusions The availability of this mitogenome provides insights into the systematics, biology, and genomics of triatomine species while also enhancing our understanding of their evolutionary relationships. However, the limited number of available mitogenomes, particularly for South American Triatoma species, underscores the need for further sequencing efforts to improve phylogenetic resolution and support comparative genomic studies. Graphical Abstract

Protozoan pathogen Trypanosoma cruzi (Chagas, 1909) is the etiologic agent of Chagas disease, which affects millions of people in Latin America. Recently, the disease has been gaining attention in Texas and the southern United States. Transmission cycle of the parasite involves alternating infection between insect vectors and vertebrate hosts (including humans, wildlife, and domestic animals). To evaluate vector T. cruzi parasite burden and feeding patterns, we tested triatomine vectors from 23 central, southern, and northeastern counties of Texas. Out of the 68 submitted specimens, the majority were genetically identified as Triatoma gerstaeckeri (Stal, 1859), with a few samples of Triatoma sanguisuga (LeConte, 1855), Triatoma lecticularia (Stal, 1859), Triatoma rubida (Uhler, 1894), and Triatoma protracta woodi (Usinger, 1939). We found almost two-thirds of the submitted insects were polymerase chain reaction-positive for T. cruzi. Bloodmeal sources were determined for most of the insects, and 16 different species of mammals were identified as hosts. The most prevalent type of bloodmeal was human, with over half of these insects found to be positive for T. cruzi. High infection rate of the triatomine vectors combined with high incidence of feeding on humans highlight the importance of Chagas disease surveillance in Texas. With our previous findings of autochthonous transmission of Chagas disease, urgent measures are needed to increase public awareness, vector control in and around homes, and Chagas screening of residents who present with a history of a triatomine exposure.

Triatomines are hematophagous insects of great epidemiological importance, since they are vectors of the protozoan Trypanosoma cruzi , the etiological agent of Chagas disease. Triatoma brasiliensis complex is a monophyletic group formed by two subspecies and six species: T . b . brasiliensis , T . b . macromelasoma , T . bahiensis , T . juazeirensis , T . lenti , T . melanica , T . petrocchiae and T . sherlocki . The specific status of several species grouped in the T . brasiliensis complex was confirmed from experimental crossing and analysis of reproductive barriers. Thus, we perform interspecific experimental crosses between T . lenti and other species and subspecies of the T . brasiliensis complex and perform morphological analysis of the gonads and cytogenetic analysis in the homeologous chromosomes of the hybrids of first generation (F1). Besides that, we rescue all the literature data associated with the study of reproductive barriers in this monophyletic complex of species and subspecies. For all crosses performed between T . b . brasiliensis , T . b . macromelasoma , T . juazeirensis and T . melanica with T . lenti , interspecific copulas occurred (showing absence of mechanical isolation), hybrids were obtained, none of the male hybrids presented the phenomenon of gonadal dysgenesis and 100% pairing between the chromosomes homeologous of the hybrids was observed. Thus, we demonstrate that there are no pre-zygotic reproductive barriers installed between T . lenti and the species and subspecies of the T . brasiliensis complex. In addition, we demonstrate that the hybrids obtained between these crosses have high genomic compatibility and the absence of gonadal dysgenesis. These results point to reproductive compatibility between T . lenti and species and subspecies of the T . brasiliensis complex (confirming its inclusion in the complex) and lead us to suggest a possible recent diversification of the taxa of this monophyletic group.

Background Plasticity in sensory perception and tolerance to xenobiotics contributes to insects’ adaptive capacity and evolutionary success, by enabling them to cope with potentially toxic molecules from the environment or internal milieu. Odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) have traditionally been studied in the context of chemoreception. However, accumulating evidence over the past few years indicates that these protein families can also sequester insecticide molecules. In doing so, the insecticide cannot reach its target site and can be more easily eliminated through the feces, complexed with these proteins. Thus, xenobiotic sequestration by OBPs and CSPs may lead to insecticide tolerance or even resistance. In the Southern Cone, the kissing bug Triatoma infestans is the main vector of Trypanosoma cruzi , the protozoan parasite that causes Chagas disease. Vectorial transmission of T. cruzi has not been interrupted in certain regions of Argentina, where several populations of T. infestans highly resistant to insecticides have been reported. Understanding the molecular mechanisms underlying resistance is crucial for designing effective vector control strategies. In this context, studying protein families involved in insecticide sequestration is essential. Results We manually corrected predicted gene models and identified new sequences of chemosensory and odorant-binding proteins in five Hemiptera species with different feeding habits. Using this information, we mined the raw genome sequence of T. infestans to identify and characterize their orthologs based on sequence conservation and phylogenetic relationships. In total, 26 chemosensory and 49 odorant-binding proteins were identified in the T. infestans genome. Phylogenetic analysis, tissue-specific expression, and molecular docking with major insecticides were performed to assess possible roles. Conclusions This work represents the first comprehensive genomic analysis of chemosensory and odorant-binding protein families across Hemiptera species, as well as the first characterization of these gene families in T. infestans using genomic data. It contributes to a better understanding of the molecular basis of chemoreception and insecticide resistance in T. infestans .

Background Chagas disease is caused by Trypanosoma cruzi , which is transmitted by triatomine vectors. The northeastern region of Brazil is endemic for Chagas disease and has the largest diversity of triatomine species. T. cruzi development in its triatomine vector depends on diverse factors, including the composition of bacterial gut microbiota. Methods We characterized the triatomines captured in the municipality of Russas (Ceará) by sequencing the cytochrome c oxidase subunit I (COI) gene. The composition of the bacterial community in the gut of peridomestic Triatoma brasiliensis and Triatoma pseudomaculata was investigated using culture independent methods based on the amplification of the 16S rRNA gene by polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), DNA fragment cloning, Sanger sequencing and 454 pyrosequencing. Additionally, we identified TcI and TcII types of T. cruzi by sequencing amplicons from the gut metagenomic DNA with primers for the mini-exon gene. Results Triatomines collected in the peridomestic ecotopes were diagnosed as T. pseudomaculata and T. brasiliensis by comparing their COI sequence with GenBank. The rate of infection by T. cruzi in adult triatomines reached 80% for T. pseudomaculata and 90% for T. brasiliensis . According to the DNA sequences from the DGGE bands, the triatomine gut microbiota was primarily composed of Proteobacteria and Actinobacteria. However, Firmicutes and Bacteroidetes were also detected, although in much lower proportions. Serratia was the main genus, as it was encountered in all samples analyzed by DGGE and 454 pyrosequencing. Members of Corynebacterinae, a suborder of the Actinomycetales, formed the next most important group. The cloning and sequencing of full-length 16S rRNA genes confirmed the presence of Serratia marcescens , Dietzia sp., Gordonia terrae , Corynebacterium stationis and Corynebacterium glutamicum . Conclusions The study of the bacterial microbiota in the triatomine gut has gained increased attention because of the possible role it may play in the epidemiology of Chagas disease by competing with T. cruzi . Culture independent methods have shown that the bacterial composition of the microbiota in the guts of peridomestic triatomines is made up by only few bacterial species.

We used an individual-based molecular multisource approach to assess the epidemiological importance of Triatoma brasiliensis collected in distinct sites and ecotopes in Rio Grande do Norte State, Brazil. In the semi-arid zones of Brazil, this blood sucking bug is the most important vector of Trypanosoma cruzi--the parasite that causes Chagas disease. First, cytochrome b (cytb) and microsatellite markers were used for inferences on the genetic structure of five populations (108 bugs). Second, we determined the natural T. cruzi infection prevalence and parasite diversity in 126 bugs by amplifying a mini-exon gene from triatomine gut contents. Third, we identified the natural feeding sources of 60 T. brasiliensis by using the blood meal content via vertebrate cytb analysis. Demographic inferences based on cytb variation indicated expansion events in some sylvatic and domiciliary populations. Microsatellite results indicated gene flow between sylvatic and anthropic (domiciliary and peridomiciliary) populations, which threatens vector control efforts because sylvatic population are uncontrollable. A high natural T. cruzi infection prevalence (52-71%) and two parasite lineages were found for the sylvatic foci, in which 68% of bugs had fed on Kerodon rupestris (Rodentia: Caviidae), highlighting it as a potential reservoir. For peridomiciliary bugs, Galea spixii (Rodentia: Caviidae) was the main mammal feeding source, which may reinforce previous concerns about the potential of this animal to link the sylvatic and domiciliary T. cruzi cycles.

Triatomine insects are vectors of Trypanosoma cruzi, a protozoan parasite that is the causative agent of Chagas' disease. This is a neglected disease affecting approximately 8 million people in Latin America. The existence of diverse pyrethroid resistant populations of at least two species demonstrates the potential of triatomines to develop high levels of insecticide resistance. Therefore, the incorporation of strategies for resistance management is a main concern for vector control programs. Three enzymatic superfamilies are thought to mediate xenobiotic detoxification and resistance: Glutathione Transferases (GSTs), Cytochromes P450 (CYPs) and Carboxyl/Cholinesterases (CCEs). Improving our knowledge of key triatomine detoxification enzymes will strengthen our understanding of insecticide resistance processes in vectors of Chagas' disease. The discovery and description of detoxification gene superfamilies in normalized transcriptomes of three triatomine species: Triatoma dimidiata, Triatoma infestans and Triatoma pallidipennis is presented. Furthermore, a comparative analysis of these superfamilies among the triatomine transcriptomes and the genome of Rhodnius prolixus, also a triatomine vector of Chagas' disease, and other well-studied insect genomes was performed. The expression pattern of detoxification genes in R. prolixus transcriptomes from key organs was analyzed. The comparisons reveal gene expansions in Sigma class GSTs, CYP3 in CYP superfamily and clade E in CCE superfamily. Moreover, several CYP families identified in these triatomines have not yet been described in other insects. Conversely, several groups of insecticide resistance related enzymes within each enzyme superfamily are reduced or lacking in triatomines. Furthermore, our qRT-PCR results showed an increase in the expression of a CYP4 gene in a T. infestans population resistant to pyrethroids. These results could point to an involvement of metabolic detoxification mechanisms on the high levels of pyrethroid resistance detected in triatomines from the Gran Chaco ecoregion. Our results help to elucidate the potential insecticide resistance mechanisms in vectors of Chagas' disease and provide new relevant information for this field. This study shows that metabolic resistance might be a contributing cause of the high pyrethroid resistance observed in wild T. infestans populations from the Gran Chaco ecoregion, area in which although subjected to intense pyrethroid treatments, vector control has failed. This study opens new avenues for further functional studies on triatomine detoxification mechanisms.