Experimental Hybrids of the Triatoma brasiliensis Species Complex Show Higher Susceptibility to the Trypanosoma cruzi Infection Than Their Parentals.

The Triatoma brasiliensis species complex is a monophyletic group encompassing two subspecies and six species. Recently, a hybrid zone of members of this complex was recorded in the state of Pernambuco. Questions concerning the capability of the hybrids to become infected with Trypanosoma cruzi have been raised. This study aimed to compare the susceptibility of Triatoma b. brasiliensis, Triatoma juazeirensis, and their experimental hybrids to infection with T. cruzi. We infected the parentals and their experimental hybrids (obtained through reciprocal crosses) through artificial feeding with citrated rabbit blood, to which the TcI 0354 strain of T. cruzi had been added. The insects were weighed before and after feeding on the rabbit blood, and then they were dissected on the 10th, 20th, and 30th day after infection. Both the hybrids and the parentals remained infected throughout the experiment. The parasite was mostly found in the epimastigote form. The number of epimastigotes was significantly lower in the stomach and small intestine of T. juazeirensis than in the hybrids or in T. b. brasiliensis. A significantly higher percentage of metacyclic trypomastigotes was detected in the small intestine and rectum of the hybrids. Hybrids demonstrated higher susceptibility to the TcI 0354 strain than their parentals, opening up new avenues to be investigated.

Unraveling the Sexual Dimorphism of First Instar Nymphs of the Giant Stick Insect, Cladomorphus phyllinus Gray, 1835, from the Atlantic Forest, Brazil.

The first instar nymphs, both male and female, of the giant stick insect Cladomorphus phyllinus Gray, 1835 were carefully described and measured, revealing a remarkable sexual dimorphism that is considered rare among insects and is poorly explored in the order Phasmida. The studied F1 nymphs originated in captivity from eggs laid by a coupled female specimen collected in the Atlantic Forest in the vicinity of Petrópolis city, state of Rio de Janeiro, Brazil. The first instar nymphs of C. phyllinus were measured and illustrated in high-resolution photographs to show the general aspects and details of sexually dimorphic traits, making clear the phenotypic differences in the sexes. A total of 100 nymphs were kept alive until morphological sexual dimorphism was confirmed and quantified. All recently hatched first instar nymphs were separated based on the presumed male and female characteristics, i.e., the presence and absence of the suture in the metanotum in the males and females, respectively, had their sexes confirmed in 100% of the specimens as previously assigned. These results confirm this new morphological trait, which here is named "alar suture" as sex-specific in the first instar nymphs, a novelty in this stage of development of sexual differentiation. In addition, the distinct conformations of the last three abdominal sternites of both sexes were recorded.

Cladomorphus petropolisensis, a New Species of Stick Insect from the Atlantic Forest, Rio de Janeiro, Brazil.

Cladomorphus petropolisensis sp. nov., a new species of stick insect from Petrópolis, Rio de Janeiro, Brazil, is herein described and compared to the other sympatric species, C. phyllinus Gray, 1835 (Phasmatidae, Cladomorphinae). The description of the new species is supported by morphological and molecular evidence. Kimura-2-parameter (K2P) intraspecific COI divergences among the holotype of C. petropolisensis sp. nov. and C. phyllinus individuals ranged from 2.9% to 4.4%, which are suggestive of distinct species, especially when considering that all Cladomorphus individuals studied were collected in the Petrópolis municipality. The new species can be distinguished from C. phyllinus Gray, 1835 by several characteristics: smaller size, the presence of two spines on the hind femora, the relative longer length of the ovipositor, and spiny tegument, especially in the mesonotum, sculpturing of the operculum of the egg.

Morphological Stasis in Time? A Triatoma brasiliensis brasiliensis Study Using Geometric Morphometrics in the Long Run.

Triatoma brasiliensis brasiliensis Neiva, 1911 is one of the most important vectors of Chagas disease in the Brazilian semiarid regions in the north-east. The risk imposed by T. b. brasiliensis to the human populations, due to frequent invasions and/or colonization of the domiciles, demands constant monitoring and control actions as well as an understanding of its evolutionary process. In this context, the following research studies the pattern of shape adaptation over time using a large dataset from 102 years of specimen collections in order to identify the morphological plasticity of this vector in Brazil. This dataset was analyzed using geometric morphometrics tools and the timescale was divided into eight different groups, containing specimens from 1912 to 2014. Geometric morphometrics analysis showed an interesting morphological stasis in the wing shape of T. b. brasiliensis, which allowed us to understand the high capacity of adaptation to changes in climate condition through time, and the invasive status which Triatoma species have around the world. Moreover, these results showed novel findings as an interesting phenotypic pattern, with no modifications in more than 100 years, leading us to understand the shape evolution in Triatominae as a vector species of diseases.

The connection between Trypanosoma cruzi transmission cycles by Triatoma brasiliensis brasiliensis: A threat to human health in an area susceptible to desertification in the Seridó, Rio Grande do Norte, Brazil.

An outbreak of Chagas disease, possibly involving its vector Triatoma brasiliensis brasiliensis, was identified in the state of Rio Grande do Norte (RN). Given the historical significance of this vector in public health, the study aimed to evaluate its role in the transmission dynamics of the protozoan Trypanosoma cruzi in an area undergoing desertification in the Seridó region, RN, Brazil. We captured triatomines in sylvatic and anthropic ecotopes. Natural vector infection was determined using parasitological and molecular methods and we identified discrete typing units (DTUs) of T. cruzi by analyzing the COII gene of mtDNA, 24Sα rDNA, and mini-exon gene. Their blood meals sources were identified by amplification and sequencing of the mtDNA cytochrome b gene. A total of 952 T. b. brasiliensis were captured in peridomestic (69.9%) and sylvatic ecotopes (30.4%). A wide range of natural infection rates were observed in peridomestic (36.0% - 71.1%) and sylvatic populations (28.6% - 100.0%). We observed the circulation of TcI and TcII DTUs with a predominance of Tcl in sylvatic and peridomestic environments. Kerodon rupestris, rocky cavy (13/39), Homo sapiens, human (8/39), and Bos taurus, ox (6/39) were the most frequently detected blood meals sources. Thus, Triatoma b. brasiliensis is invading and colonizing the human dwellings. Furthermore, high levels of natural infection, coupled with the detection of TcI and TcII DTUs, and also the detection of K. rupestris and H. sapiens as blood meals sources of infected T. b. brasiliensis indicate a risk of T. cruzi transmission to human populations in areas undergoing desertification.

Do the new triatomine species pose new challenges or strategies for monitoring Chagas disease? An overview from 1979-2021.

Chagas disease persists as one of the most important, and yet most neglected, diseases in the world, and several changes in its epidemiological aspects have been recorded since its discovery. Currently, some of the most relevant changes are related to: (i) the reduction in the incidence of the endemic due to the control of the most important vectors, Triatoma infestans and Rhodnius prolixus, in many countries; (ii) the migration of human populations spreading cases of the disease throughout the world, from endemic to non-endemic areas, transforming Chagas disease into a global threat; and (iii) new acute cases and deaths caused by oral transmission, especially in the north of Brazil. Despite the reduction in the number of cases, new challenges need to be responded to, including monitoring and control activities aiming to prevent house infestation by the secondary vectors from occurring. In 1979, Lent & Wygodzinsky(1) published the most complete review of the subfamily Triatominae, encompassing 111 recognised species in the taxon. Forty-two years later, 46 new species and one subspecies have been described or revalidated. Here we summarise the new species and contextualise them regarding their ecology, epidemiologic importance, and the obstacles they pose to the control of Chagas disease around the world.

Dynamics of food sources, ecotypic distribution and Trypanosoma cruzi infection in Triatoma brasiliensis from the northeast of Brazil.

Innovative approaches used to combat Chagas disease transmission tend to combine a set of comprehensive efforts to understand the ecology of local vectors. In this work we identified molecularly the blood meal of 181 Triatoma brasiliensis, distributed in 18 populations (8 sylvatic and 10 peridomestic), which were collected across a range of 240 km (East-West) and 95 km (North-South) in the semi-arid region of northeastern, Brazil. We used the vertebrate mitochondrial gene (cytochrome B) sequencing applied to DNA isolated from bug midgut to identify the insect blood meal sources via the BLAST procedure. The peridomestic populations were classified according to two main hypotheses of site-occupancy for T. brasiliensis: the first says that the infestation is mainly driven by structures that resemble its natural habitat (stony-like ecotopes) and the second assumes that it is associated with key-hosts (rodents and goats). Rodents of the Caviidae family (Galea spixii and Kerodon rupestris) were identified as the key-host of T. brasiliensis, but also the potential Trypanosoma cruzi reservoir-able to connect the sylvatic and domestic T. cruzi cycle. Cats also deserve to be studied better, as potential T. cruzi reservoirs. By modeling the food sources + site-occupancy + T. cruzi natural infection, we identified man-made ecotopes suitable for forming dense triatomine infestations with high rates of T. cruzi natural infection, which may be taken into account for vector control measures.

Drivers of molecular and morphometric variation in Triatoma brasiliensis (Hemiptera: Triatominae): the resolution of geometric morphometrics for populational structuring on a microgeographical scale.

BACKGROUND: The protozoan Trypanosoma cruzi circulates in semiarid areas of northeastern Brazil in distinct ecotopes (sylvatic, peridomestic and domestic) where Triatoma brasiliensis Neiva, 1911 is the most important Chagas disease vector. In this study, we analyzed microevolutionary and demographic aspects of T. brasiliensis populations at the ecotypic, micro and macro-geographic scales by combining morphometrics and molecular results. Additionally, we aimed to address the resolution of both markers for delimiting populations in distinct scales. METHODS: We sampled populations of T. brasiliensis from distinct ecotypic and geographic sites in the states Rio Grande do Norte (RN) and Paraíba (PB). The geometric morphometry was carried out with 13 landmarks on the right wings (n = 698) and the genetic structure was assessed by sequencing a region of cytochrome b mitochondrial gene (n = 221). Mahalanobis distance (MD) and coefficient of molecular differentiation (ΦST) were calculated among all pairs of populations. The results of comparisons generated MD and ΦST dendrograms, and graphics of canonical variate analysis (CVA). RESULTS: Little structure was observed for both markers for macro-geographic scales. Mantel tests comparing geographic, morphometric and genetic matrices showed low correlation (all R2 < 0.35). The factorial graphics built with the CVA evidenced population delimitation for the morphometric data at micro-geographic scales. CONCLUSIONS: We believe that T. brasiliensis carries in its genotype a source of information to allow the phenotypical plasticity across its whole distribution for shaping populations, which may have caused a lack of population delimitation for CVAs in morphometric analysis for macro-geographic scale analysis. On the other hand, the pattern of morphometric results in micro-geographic scales showed well-defined groups, highlighting the potential of this tool to inferences on the source for infestation.

Triatoma brasiliensis species complex: characterization of the external female genitalia.

The Triatoma brasiliensis complex is composed of six species (Triatoma bahiensis, T. juazerensis, T. lenti, T. melanica, T. petrocchiae, and T. sherlocki) and two subspecies (T. brasiliensis brasiliensis and T. b. macromelasoma). Phylogenetic studies have shown that it is a monophyletic group, but the morphological relationships among the members can be better understood. We applied a tool of high resolution based on morphology to identify details that characterize the female genitals for each member of this group. The external genital structures of five to fifteen females of each taxon were analyzed. Insects had their abdomen transversely cut to separate the last abdominal segments, and representative illustrations obtained via scanning electron microscopy (SEM) are shown. Observations were performed in the dorsal and the ventral views. The morphological characterization of female external genitalia allowed a differentiation of each species/subspecies. The subspecies T. b. brasiliensis and T. b. macromelasoma were the most similar. On the other hand, dorsal view of structures evidenced some unique characteristics for T. petrocchiae and T. sherlocki. Regarding these structures for T. petrocchiae, the differentiation was in accordance with molecular studies, since this species exhibits the highest genetic distances in relation to other species of T. brasiliensis complex.

As Borboletas, o Besouro e a Fada da Biodiversidade

Obra ilustrada com espécimes da Coleção Entomológica do IOC promove reflexão sobre importância dos diferentes seres vivos para o equilíbrio ambiental. O material está disponível para acesso online. Este livro direcionado ao público infanto-juvenil, principalmente, representa uma expressão de amor à natureza, especificamente aos insetos, muitas vezes ignorados ou vistos de forma negativa.

Molecular eco-epidemiology on the sympatric Chagas disease vectors Triatoma brasiliensis and Triatoma petrocchiae: Ecotopes, genetic variation, natural infection prevalence by trypanosomatids and parasite genotyping.

Triatoma petrocchiae is the newly member of the Triatoma brasiliensis species complex. This species overlaps with T. brasiliensis in geographic and ecotypic occupation in the sylvatic habitat because both inhabit rocky outcrops in the semi-arid portion of Brazilian northeast. In this region T. brasiliensis is the most important Chagas disease vector because it constantly colonizes domiciles. In contrast, T. petrocchiae is rarely found in peri or intradomiciliary habitats - reason why little is known about this species. Therefore, Here, we present information for the first time on. the T. petrocchiae ecotopes, genetic diversity, Trypanosoma cruzi prevalence/genotyping in comparison to T. brasiliensis. We found T. brasilensis (N = 223) and T. petrocchiae (N = 69) in co-habitation in rocky outcrops in three Districts of Paraíba and Rio Grande do Norte states. Forty-tree T. petrocchiae insects of eleven sampling spots (composing three geographic populations) were genotyped for the mitochondrial Cyt B gene and little geographic structure was observed. Tajima's D test suggested that species is evolving toward a mutation-drift equilibrium in our collection range. Sylvatic T. petrocchiae had 4% (3/68) of infected insects by T. cruzi, whereas T. brasiliensis had 26% (59/223). Fluorescent Fragment Length Barcoding demonstrated that all three T. petrocchiae harbored TcI whereas T. brasiliensis had TcI, but also TcIII, TcII/TcVI and T. rangeli genotype A, sometimes under mixed infections. None of infected T. petrocchiae were carrying mixed infections. However, this result should be confirmed using a larger pool of infected bugs. We here presented the first documentation of T. rangeli infecting T. brasiliensis. The finding of infected T. petrocchiae calls for constant vector monitoring because the epidemiologic scenario is dynamic and sylvatic vectors are progressively found in adaptation to anthropic environments.

Different anesthetics on the efficacy of inferior alveolar nerve block in patients with irreversible pulpitis: A network systematic review and meta-analysis.

BACKGROUND: The authors of this systematic review and meta-analysis aimed to evaluate the effect of different anesthetics on the efficacy of inferior alveolar nerve block (IANB) in patients with irreversible pulpitis. TYPES OF STUDIES REVIEWED: The authors conducted a search of MEDLINE databases (PubMed, Scopus, Web of Science, Cochrane Central Register of Controlled Trials, Latin American and Caribbean Health Sciences Literature, and Brazilian Library of Dentistry). There was no restriction on publication year or idiom. The gray literature was also explored. The authors included only randomized clinical trials that compared different anesthetics in the efficacy of IANB in patients with irreversible pulpitis. The risk of bias was evaluated by using the Cochrane Collaboration's tool. A random-effects Bayesian mixed treatment comparison model was used to compare different anesthetic solutions in randomized clinical trials with low or unclear risk of bias. Heterogeneity was assessed by using Cochran Q test and I2 statistics. Quality of evidence was assessed by using the Grading of Recommendations Assessment, Development and Evaluation approach. RESULTS: A total of 7,981 studies were identified; only 16 met the eligibility criteria, and they were all meta-analyzed. A significant difference was observed in the pair lidocaine versus articaine, with higher success with articaine (risk ratio, 0.76; 95% confidence interval, 0.63 to 0.88) in the mixed treatment comparison analysis, as this comparison was graded as high-quality evidence. The probability of success for each treatment was 73% for articaine, 57% for prilocaine, 55% for mepivacaine, 53% for bupivacaine, and 12% for lidocaine. This ranking was considered high quality of evidence. CONCLUSIONS AND PRACTICAL IMPLICATIONS: The use of articaine can increase the IANB success rate in patients with irreversible pulpitis. Among the anesthetic solutions, lidocaine was the least effective.

Bionomic notes on parthenogenetic females and a record of parasitism by Forcipomyia Meigen (Diptera: Ceratopogonidae) in the stick insect Cladoxerus cryphaleus (Westwood) (Phasmatodea: Phasmatidae)

ABSTRACT Stick insects (Phasmatodea) are among the least studied insect groups in Brazil. Although in recent years there has been an increase in the number of published studies on taxonomy and morphology of Brazilian stick insects, they remain very little-known concerning biological and bionomic aspects. From five females of Cladoxerus cryphaleus (Phasmatidae: Cladomorphinae) collected in the Iguaçu National Park, Paraná, Brazil, a captive colony of parthenogenetic females was started, based on which data on longevity, fertility, and viability of eggs of this species were recorded for the first time. After imaginal molting, the 21 females studied had an average longevity of 103.7 days. Each female produced on average 125.3 eggs, which had a hatching rate of 34.2%. In addition, we recorded a C. cryphaleus male nymph being parasitized by a biting midge of the subgenus Forcipomyia (Microhelea) (Diptera: Ceratopogonidae). The male, in pre-imaginal instar and already parasitized, was collected in the municipality of Petrópolis, Rio de Janeiro.

An updated and illustrated dichotomous key for the Chagas disease vectors of Triatomabrasiliensis species complex and their epidemiologic importance.

In the subfamily Triatominae, Triatoma exhibits the largest number of species, which are arranged in complexes. For the T.brasiliensis species complex, recent investigations based on results of geometric morphometrics combined with phylogeny have provided evidence that it should be composed of seven species: T.brasiliensis, T.bahiensis, T.juazeirensis, T.lenti, T.melanica, T.petrocchiae, and T.sherlocki, in which T.brasiliensis is divided in two subspecies: T.b.brasiliensis and T.b.macromelasoma. A taxonomic key is presented to identify each taxon. Among members of this complex, T.b.brasiliensis is the most important in an epidemiologic context, due to its high prevalence in natural infection by Trypanosomacruzi combined with a pronounced adaptation to domiciliary habitats. However, some members may be currently invading and colonizing homes, a process known as domiciliation. Therefore, the key presented here may be potentially useful for researchers as well as those involved in vector control measures.

High Triatoma brasiliensis Densities and Trypanosoma cruzi Prevalence in Domestic and Peridomestic Habitats in the State of Rio Grande do Norte, Brazil: The Source for Chagas Disease Outbreaks?

AbstractA total of 2,431 Triatoma brasiliensis were collected from 39 populations of Paraíba (PB) and Rio Grande do Norte (RN) states, Brazil. In PB, Trypanosoma cruzi infection was not detected in either peridomestic or domestic vector populations. In contrast, in RN, T. brasiliensis was detected with high parasite prevalence in these ecotopes (30.7-40.0%). Moreover, peridomicile insect population densities were more than double the average densities of all other settings evaluated (19.17 versus < 8.94 triatomine/man-hour). Genotyped parasites evidenced a mix of T. cruzi lineages circulating in both peridomestic and sylvatic populations. Although vector control efforts have dramatically decreased Chagas disease transmission to humans, recent outbreaks have been detected in four municipalities of RN state. Our results clearly evidence a worrisome proximity between infected vectors and humans in RN. Indeed, finding of infected T. brasiliensis inside homes is routinely recorded by local vector control surveillance staff around the outbreak area, challenging the current and conventional view that vector transmissions are controlled in northeastern Brazil. This scenario calls for strengthening vector control surveillance and interventions to prevent further Chagas transmission, especially in RN State.

Biology of Triatoma sherlocki (Hemiptera: Reduviidae) Under Laboratory Conditions: Biological Cycle and Resistance to Starvation.

Triatoma sherlocki Papa, Jurberg, Carcavallo, Cerqueira & Barata was described in 2002, based on specimens caught in the wild in the municipality of Gentio do Ouro, Bahia, Brazil. In 2009, nymphs and adults were detected inside homes and sylvatic specimens were positive for Trypanosoma cruzi (Chagas). No information on the bionomics of T. sherlocki exists, although such data are considered essential to estimate its vector and colonization potential in domestic environments. Herein, the biological cycle of T. sherlocki was studied based on 123 eggs, with nymphs and adults fed on Mus musculus (Linnaeus). Nymphal development time phases, number of meals consumed, and stage-specific mortality rates were analyzed. Survival time under starvation conditions was measured between ecdysis and death among 50 nymphs (first to fifth instar) and 50 male and female adults. The median development time from egg to adult was 621.0 (CI: 489-656) d. The number of meals consumed ranged from 1 to 20 for nymphs of the first to fifth instar. The fifth instar showed the greatest resistance to starvation, with a mean of 156.5 d. The high number of meals consumed by T. sherlocki favored infection with and transmission of T. cruzi. The full development of this species under laboratory conditions with a low mortality rate indicates that this vector presents biological characteristics that may contribute to its adaptation to artificial human ecotopes. Its high resistance to starvation emphasizes the importance of entomological surveillance for this species.

Combined phylogenetic and morphometric information to delimit and unify the Triatoma brasiliensis species complex and the Brasiliensis subcomplex.

"Triatoma brasiliensis species complex" was defined as a monophyletic group of the species: T. brasiliensis, T. juazeirensis, T. melanica, and T. sherlocki. An alternative grouping scheme proposed the concept of "Brasiliensis subcomplex" which included the former species together with T. melanocephala, T. petrocchiae, T. lenti, T. tibiamaculata, and T. vitticeps. To evaluate the relationship among these taxa we combined the results obtained with four mitochondrial genes (12S, 16S, COI and Cytb, adding to 1811bp) and geometric morphometric analysis of wings and heads. Panstrongylus megistus was included in the analysis as it was previously found related to T. tibiamaculata, T. melanocephala and T. vitticeps. The results of both molecular and morphometric approaches clearly grouped the species analyzed into two monophyletic units, supported by both genetic and wing variability. The first one (G1) comprises the four species originally included in the T. brasiliensis species complex plus T. lenti and T. petrocchiae. The second group (G2) was composed by T. melanocephala, T. tibiamaculata and T. vitticeps, and remarkably, P. megistus if considering wing variability and phylogenetic results. Nevertheless, geometric morphometrics of heads provided a quantitative measurement that discriminates Panstrongylus from the Triatoma species based on the position of the antennal insertion relative to eyes, as it is used as the generic distinctive character. The discrepancy among approaches questions the validity of this character to define Panstrongylus genus. Independently of the chosen group definition -"T. brasiliensis species complex" or "Brasiliensis subcomplex"-we propose to delimit it to species of G1 that are all associated with the Caatinga biome in the Brazilian Northeast. G2 are the ones associated with the Atlantic Forest biome.

Triatomine bugs, their microbiota and Trypanosoma cruzi: asymmetric responses of bacteria to an infected blood meal.

BACKGROUND: Triatomine bugs (Hemiptera: Reduviidae) are vectors of the flagellate Trypanosoma cruzi, the causative agent of Chagas disease. The study of triatomine gut microbiota has gained relevance in the last years due to its possible role in vector competence and prospective use in control strategies. The objective of this study is to examine changes in the gut microbiota composition of triatomines in response to a T. cruzi-infected blood meal and identifying key factors determining those changes. RESULTS: We sampled colony-reared individuals from six triatomine vectors (Panstrongylus megistus, Rhodnius prolixus, Triatoma brasiliensis, T. infestans, T. juazeirensis and T. sherlocki) comparing experimentally T. cruzi strain 0354-challenged and non-challenged insects. The microbiota of gut and gonad tissues was characterized using high throughput sequencing of region V3-V4 of bacterial 16S rRNA gene. The triatomine microbiota had a low intra-individual diversity, and a high inter-individual variation within the same host species. Arsenophonous appeared as the dominant triatomine bacterial symbiont in our study (59% of the total 16S coverage), but there were significant differences in the distribution of bacterial genera among vectors. In Rhodnius prolixus the dominant symbiont was Pectobacterium. CONCLUSIONS: Trypanosoma cruzi-challenge significantly affects microbiota composition, with challenged vectors harbouring a significantly more diverse bacterial community, both in the gut and the gonads. Our results show that blood-feeding with T. cruzi epimastigotes strongly affects microbiota composition in a species-specific manner. We suggest that triatomine-adapted enterobacteria such as Arsenophonus could be used as stable vectors for genetic transformation of triatomine bugs and control of Chagas disease.

Under-Expression of Chemosensory Genes in Domiciliary Bugs of the Chagas Disease Vector Triatoma brasiliensis.

BACKGROUND: In Latin America, the bloodsucking bugs Triatominae are vectors of Trypanosoma cruzi, the parasite that causes Chagas disease. Chemical elimination programs have been launched to control Chagas disease vectors. However, the disease persists because native vectors from sylvatic habitats are able to (re)colonize houses-a process called domiciliation. Triatoma brasiliensis is one example. Because the chemosensory system allows insects to interact with their environment and plays a key role in insect adaption, we conducted a descriptive and comparative study of the chemosensory transcriptome of T. brasiliensis samples from different ecotopes. METHODOLOGY/PRINCIPAL FINDING: In a reference transcriptome built using de novo assembly, we found transcripts encoding 27 odorant-binding proteins (OBPs), 17 chemosensory proteins (CSPs), 3 odorant receptors (ORs), 5 transient receptor potential channel (TRPs), 1 sensory neuron membrane protein (SNMPs), 25 takeout proteins, 72 cytochrome P450s, 5 gluthatione S-transferases, and 49 cuticular proteins. Using protein phylogenies, we showed that most of the OBPs and CSPs for T. brasiliensis had well supported orthologs in the kissing bug Rhodnius prolixus. We also showed a higher number of these genes within the bloodsucking bugs and more generally within all Hemipterans compared to the other species in the super-order Paraneoptera. Using both DESeq2 and EdgeR software, we performed differential expression analyses between samples of T. brasiliensis, taking into account their environment (sylvatic, peridomiciliary and domiciliary) and sex. We also searched clusters of co-expressed contigs using HTSCluster. Among differentially expressed (DE) contigs, most were under-expressed in the chemosensory organs of the domiciliary bugs compared to the other samples and in females compared to males. We clearly identified DE genes that play a role in the chemosensory system. CONCLUSION/SIGNIFICANCE: Chemosensory genes could be good candidates for genes that contribute to adaptation or plastic rearrangement to an anthropogenic system. The domiciliary environment probably includes less diversity of xenobiotics and probably has more stable abiotic parameters than do sylvatic and peridomiciliary environments. This could explain why both detoxification and cuticle protein genes are less expressed in domiciliary bugs. Understanding the molecular basis for how vectors adapt to human dwellings may reveal new tools to control disease vectors; for example, by disrupting chemical communication.

Vector capacity of members of Triatoma brasiliensis species complex: The need to extend Chagas disease surveillance to Triatoma melanica.

We conducted a lab-based comparative study on vector capacity features of two species of triatomines: Triatoma brasiliensis and T. melanica. Both are members of the T. brasiliensis species complex. The former is the most important Chagas disease vector in the northeastern region of Brazil. To date, no transmission via T. melanica has been recorded. Immature insects exhibited distinct intermoult periods without a direct relationship to a given species. Females of T. brasiliensis consumed an average of 1.9 times more meals (mean = 12.92 vs 6.63) and survived for a shorter period (mean =330.8 days) than T. melanica (mean = 365.2 days), probably due to the cost of reproduction (all significant at P<0.05). These data support the idea that T. brasiliensis is more adapted to lab conditions and is more able to infest domiciles than T. melanica. We also found significant distinctions in other features between these species, such as the elapsed time without eating before molting, which was higher for the second, third, and fifth nymph stages of T. melanica. Regarding features analyzed related to vector capacity, insects of all life stages of both species were considered competent to transmit Trypanosoma cruzi because they needed many feedings (mean =1.5-3.82) to moult and because a high proportion (>39%) of insects defecated rapidly (<30 s) after feeding. Overall, results highlight the need to extend vector surveillance to T. melanica.