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Triatomines (kissing bugs) and tsetse flies (genus: Glossina) are natural vectors of Trypanosoma cruzi and Trypanosoma brucei, respectively. T. cruzi is the causative agent of Chagas disease, endemic in Latin America, while T. brucei causes African sleeping sickness disease in sub‐Saharan Africa. Both triatomines and tsetse flies are host to a diverse community of gut microbiota that co‐exist with the parasites in the gut. Evidence has shown that the gut microbiota of both vectors plays a key role in parasite development and transmission. However, knowledge on the mechanism involved in parasite–microbiota interaction remains limited and scanty. Here, we attempt to analyse Trypanosoma spp. and gut microbiota interactions in tsetse flies and triatomines, with a focus on understanding the possible mechanisms involved by reviewing published articles on the subject. We report that interactions between Trypanosoma spp. and gut microbiota can be both direct and indirect. In direct interactions, the gut microbiota directly affects the parasite via the formation of biofilms and the production of anti‐parasitic molecules, while on the other hand, Trypanosoma spp. produces antimicrobial proteins to regulate gut microbiota of the vector. In indirect interactions, the parasite and gut bacteria affect each other through host vector‐activated processes such as immunity and metabolism. Although we are beginning to understand how gut microbiota interacts with the Trypanosoma parasites, there is still a need for further studies on functional role of gut microbiota in parasite development to maximize the use of symbiotic bacteria in vector and parasite control. [ABSTRACT FROM AUTHOR]

Chagas disease is considered one of the most important human parasitosis in the United States. This disease is mainly transmitted by insects of the subfamily Triatominae. The chemical vector control is the main tool for reducing the incidence of the disease. However, the presence of triatomines after pyrethroids spraying has been reported in some regions, as in the case of Triatoma infestans in Argentina and Bolivia. The presence of insects can be explained by the colonization from neighbouring areas, the reduction of insecticide dose to sublethal levels due to environmental factors, and/or by the evolution of insecticide resistance. In the last two scenarios, a proportion of the insects is not killed by insecticide and gives rise to residual populations. This article focuses on the toxicological processes associated with these scenarios in triatomines. Sublethal doses may have different effects on insect biology, that is, sublethal effects, which may contribute to the control. In addition, for insect disease vectors, sublethal doses could have negative effects on disease transmission. The study of sublethal effects in triatomines has focused primarily on the sequence of symptoms associated with nervous intoxication. However, the effects of sublethal doses on excretion, reproduction and morphology have also been studied. Rhodnius prolixus and T. infestans and pyrethroids insecticides were the triatomine species and insecticides, respectively, mainly studied. Insecticide resistance is an evolutionary phenomenon in which the insecticide acts as a selective force, concentrating on the insect population's pre‐existing traits that confer resistance. This leads to a reduction in the susceptibility to the insecticide, which was previously effective in controlling this species. The evolution of resistance in triatomines received little attention before the 2000s, but after the detection of the first focus of resistance associated with chemical control failures in T. infestans from Argentina in 2002, the study of resistance increased remarkably. A significant number of works have studied the geographical distribution, the resistance mechanisms, the biological modifications associated with resistance, the environmental influences and the genetic of T. infestans resistant to pyrethroid insecticides. Currently, studies of insecticide resistance are gradually being extended to other areas and other species. The aim of this article was to review the knowledge on both phenomena (sublethal effects and insecticide resistance) in triatomines. For a better understanding of this article, some concepts and processes related to insect‐insecticide interactions, individual and population toxicology and evolutionary biology are briefly reviewed. Finally, possible future lines of research in triatomine toxicology are discussed. [ABSTRACT FROM AUTHOR]

Ecological theory predicts that species that can utilise a greater diversity of resources and, therefore, have wider niche breadths should also occupy larger geographic areas (the 'niche breadth-range size hypothesis'). Here, we tested this hypothesis for a blood-sucking group of insects of medical significance: the Triatominae (aka 'kissing bugs') (Hemiptera: Reduviidae). Given that niches can be viewed from different perspectives, we tested this hypothesis based on both dietary and climatic niches. We assembled the most complete dataset of triatomine feeding patterns to date by reviewing 143 studies from the literature up to 2021 and tested whether the niche breadth-range size hypothesis held for this group for both dietary and climatic components of the niche. Temperature and precipitation niche breadths were estimated from macro-environmental variables, while diet breadth was calculated based on literature data that used PCR and/or ELISA to identify different types of hosts as blood sources per triatomine species. Our results showed that temperature and precipitation niche breadths, but not dietary breadth, were positively correlated with range sizes, independent of evolutionary history among species. These findings support the predictions from the range size-niche breadth hypothesis concerning climate but not diet, in Triatominae. It also shows that support for the niche breadth-range size hypothesis is dependent upon the niche axis under consideration, which can explain the mixed support for this hypothesis in the ecological literature. Author summary: Many triatomine species carry the parasite Trypanosoma cruzi, a flagellate protozoan that causes Chagas disease in animals and humans, posing a long-standing public health threat to communities in the Global South. We investigated how the niche of triatominae species correlates with their geographic range. We compiled a comprehensive dataset on their feeding habits and environmental preferences and found that temperature and precipitation niche breadth correlated geographic range size but dietary breadths did not. These findings highlight the complexity of ecological relationships and contribute to a better understanding of how species interact with their environment, and can play a crucial role in determining the range of these vectors. Thus, this knowledge can aid in the development of more effective strategies for managing vector-borne diseases. [ABSTRACT FROM AUTHOR]

The molecular bases of animal behaviour are intricate due to the pleiotropic nature of behaviour‐modulating genes, which are often expressed across multiple tissues. The foraging gene (for) encodes a cGMP‐dependent protein kinase (PKG), pivotal in regulating downstream target proteins through phosphorylation. In insects, for has been implicated in various behavioural contexts and physiological processes regarding searching for food. Rhodnius prolixus, a hematophagous bug that transmits Trypanosoma cruzi, the causative agent of Chagas disease, exhibits specific activity patterns associated with its hematophagous behaviour. Our previous work demonstrated a correlation between locomotor activity profiles and the expression of Rpfor, suggesting its involvement in modulating triatomine locomotion. In this study, we investigated the impact of Rpfor knockdown on locomotory activity, host‐seeking behaviour, feeding performance and lipid metabolism in R. prolixus nymphs. Using RNA interference, we achieved a significant reduction of Rpfor expression in both the brain and fat body of R. prolixus nymphs. Knocked‐down nymphs exhibited diminished non‐oriented locomotory activity compared with controls, without altering the characteristic bimodal pattern of activity. Additionally, they displayed an increased tendency to approach a host, suggesting a role for Rpfor in modulating host‐seeking behaviour. Feeding performance and lipid metabolism remained unaffected by Rpfor knockdown. Our findings underscore the multifaceted role of Rpfor in modulating locomotor activity and host‐seeking behaviour in R. prolixus nymphs, shedding light on the molecular mechanisms underlying their hematophagous behaviour and potential implications for disease transmission. Further research is necessary to elucidate the intricate interplay between Rpfor expression, behaviour and physiological processes in triatomine bugs. [ABSTRACT FROM AUTHOR]

The study focuses on identifying and understanding the ecological dynamics of Triatoma breyeri in Bolivia. Morphological identification and molecular analysis using gene fragments (COI, CytB and 16S) confirms T. breyeri's presence and its relation to other species. The species has been consistently found in the Estancia-Mataral–La Palma region since 2010 but has not spread to other regions in Bolivia. The region of occurrence is a small characteristic dry inter-Andean valley. A MaxEnt model suggests part of the Bolivian Montane Dry Forest ecoregion serves as a unique habitat within its range. The infrequent presence in Bolivia and the distance from its main range in Argentina suggest recent accidental introduction, possibly through human transport. Further research is needed to comprehend its persistence in this small area of Bolivia. [ABSTRACT FROM AUTHOR]

Triatomines of the species Triatoma sherlocki are considered sylvatic; however, household invasion appears imminent, potentially carrying Trypanosoma cruzi, the causative agent of Chagas disease. The aim of this study was to report the first occurrence of a colony of T. sherlocki infected by T. cruzi in a subsistence pig farm. Triatomines collected underwent polymerase chain reaction (PCR) technique for T. cruzi detection and determination of blood meal source. The 19 triatomines collected in the pig farm were of the species T. sherlocki, comprising 26.3% nymphs (5/19), 52.6% males (10/19) and 21.1% females (4/19). PCR showed that 15.8% (3/19) of triatomines were infected by T. cruzi. The only detected blood meal source in triatomines (n = 11) was the domestic mammal Sus scrofa, commonly known as domestic pig, indicating that T. sherlocki is an opportunist, feeding on available vertebrates in the environment, including domestic animals such as pigs. These results highlight the possibility of domiciliation of the species T. sherlocki and its potential role in bridging the transmission of T. cruzi between sylvatic and domestic environments. [ABSTRACT FROM AUTHOR]

Assassin bugs (Hemiptera: Reduviidae Latreille) comprise not only one of the largest radiations of predatory animals (22 subfamilies; >6,800 spp.) but also include the medically important kissing bugs (Triatominae Jeannel). Reduviidae are morphologically diverse, engage in an astounding array of predatory strategies and have evolved some of the most unique anti‐predator and stealth techniques in the animal kingdom. While significant progress has been made to reveal the evolutionary history of assassin bugs and revise their taxonomy, the non‐monophyly of the second largest assassin bug subfamily, Reduviinae Latreille, remains to be addressed. Leveraging phylogenomic data (2,291 loci) and 112 morphological characters, we performed the first data‐ and taxon‐rich (195 reduvioid taxa) combined phylogenetic analysis across Reduvioidea and reconstructed morphological diagnostic features for major lineages. We corroborated the rampant polyphyly of Reduviinae that demands substantial revisions to the subfamilial and tribal classification of assassin bugs. Our new classification for Reduviidae reduces the number of subfamilies to 19 and recognizes 40 tribes. We describe three new subfamilies to accommodate distantly related taxa previously classified as Reduviinae (Heteropinae subfam. nov., Nanokeralinae subfam. nov., and Pasirinae subfam. nov.). Triatominae sensu nov. are expanded to include closely related predatory reduviine genera. Cetherinae Jeannel, Chryxinae Champion, Pseudocetherinae Villiers, Salyavatinae Amyot & Serville and Sphaeridopinae Amyot & Serville are treated as junior synonyms of Reduviinae sensu nov. Epiroderinae Distant are synonymized with Phimophorinae Handlirsch sensu nov. and Bactrodini Stål stat. nov. are reclassified as a tribe of Harpactorinae Amyot & Serville. Psophidinae Distant is treated as a valid subfamily. This new classification represents a robust framework for future taxonomic and evolutionary research on assassin bugs.Zoobank Registration: http://zoobank.org/urn:lsid:zoobank.org:pub:2310C9AA-0D53-4EF6-9E75-C2B3A98CE096 [ABSTRACT FROM AUTHOR]

Introduction: Triatomines are vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. Currently, there is no vaccine against this disease. Thus, control of the insect vector population is the main strategy available to reduce the number of cases. Triatomines are considered obligate hematophagous, but different alternative feeding behaviors were described, such as haemolymphagy or plant feeding. Methods: To determine the preference for sugar feeding in nymphs and adults of Rhodnius prolixus, the insects were exposed a piece of cotton containing bromophenol blue plus sucrose. In addition, we offered several sugars for different species of triatomines, and tested sugar meals as a route of delivery of insecticides in first-instar nymphs of R. prolixus. The effect of sugar feeding on the physiology of these different species of triatomines was recorded. Results: First instar nymphs ingested sucrose more strongly than other stages, and showed high mortality rates. In different species of triatomines, sucrose induced an ingestion, but engorgement varied according to the species. R. prolixus nymphs showed an indiscriminate intake of various sugars, with very different physiological effects. Furthermore, ingesting different combinations of insecticides + sugar significantly reduced insect survival. Discussion: In summary, we described for the first-time sugar feeding as a widespread behavior in several species of triatomines, and the possibility of the use of toxic sugar baits for the control of these vectors. The knowledge of feeding behavior in these insects can be fundamental for the development of new strategies to control Chagas disease. [ABSTRACT FROM AUTHOR]

Background: The emergence of pyrethroid resistance has threatened the elimination of Triatoma infestans from the Gran Chaco ecoregion. We investigated the status and spatial distribution of house infestation with T. infestans and its main determinants in Castelli, a municipality of the Argentine Chaco with record levels of triatomine pyrethroid resistance, persistent infestation over 2005–2014, and limited or no control actions over 2015–2020. Methods: We conducted a 2-year longitudinal survey to assess triatomine infestation by timed manual searches in a well-defined rural section of Castelli including 14 villages and 234 inhabited houses in 2018 (baseline) and 2020, collected housing and sociodemographic data by on-site inspection and a tailored questionnaire, and synthetized these data into three indices generated by multiple correspondence analysis. Results: The overall prevalence of house infestation in 2018 (33.8%) and 2020 (31.6%) virtually matched the historical estimates for the period 2005–2014 (33.7%) under recurrent pyrethroid sprays. While mean peridomestic infestation remained the same (26.4–26.7%) between 2018 and 2020, domestic infestation slightly decreased from 12.2 to 8.3%. Key triatomine habitats were storerooms, domiciles, kitchens, and structures occupied by chickens. Local spatial analysis showed significant aggregation of infestation and bug abundance in five villages, four of which had very high pyrethroid resistance approximately over 2010–2013, suggesting persistent infestations over space-time. House bug abundance within the hotspots consistently exceeded the estimates recorded in other villages. Multiple regression analysis revealed that the presence and relative abundance of T. infestans in domiciles were strongly and negatively associated with indices for household preventive practices (pesticide use) and housing quality. Questionnaire-derived information showed extensive use of pyrethroids associated with livestock raising and concomitant spillover treatment of dogs and (peri) domestic premises. Conclusions: Triatoma infestans populations in an area with high pyrethroid resistance showed slow recovery and propagation rates despite limited or marginal control actions over a 5-year period. Consistent with these patterns, independent experiments confirmed the lower fitness of pyrethroid-resistant triatomines in Castelli compared with susceptible conspecifics. Targeting hotspots and pyrethroid-resistant foci with appropriate house modification measures and judicious application of alternative insecticides with adequate toxicity profiles are needed to suppress resistant triatomine populations and prevent their eventual regional spread. [ABSTRACT FROM AUTHOR]

Introduction: Trypanosoma cruzi is a protozoan parasite that causes the tropical ailment known as Chagas disease, which has its origins in South America. Globally, it has a major impact on health and is transported by insect vector that serves as a parasite. Given the scarcity of vaccines and the limited treatment choices, we conducted a comprehensive investigation of core proteomics to explore a potential reverse vaccine candidate with high antigenicity. Methods: To identify the immunodominant epitopes, T. cruzi core proteomics was initially explored. Consequently, the vaccine sequence was engineered to possess characteristics of non-allergenicity, antigenicity, immunogenicity, and enhanced solubility. After modeling the tertiary structure of the human TLR4 receptor, the binding affinities were assessed employing molecular docking and molecular dynamics simulations (MDS). Results: Docking of the final vaccine design with TLR4 receptors revealed substantial hydrogen bond interactions. A server-based methodology for immunological simulation was developed to forecast the effectiveness against antibodies (IgM + IgG) and interferons (IFN-g). The MDS analysis revealed notable levels of structural compactness and binding stability with average RMSD of 5.03 Aring;, beta-factor 1.09e +5 Å, Rg is 44.7 Aring; and RMSF of 49.50 Aring;. This is followed by binding free energies calculation. The system stability was compromised by the complexes, as evidenced by their corresponding Gibbs free energies of -54.6 kcal/mol. Discussion: Subtractive proteomics approach was applied to determine the antigenic regions of the T cruzi. Our study utilized computational techniques to identify B- and T-cell epitopes in the T. cruzi core proteome. In current study the developed vaccine candidate exhibits immunodominant features. Our findings suggest that formulating a vaccine targeting the causative agent of Chagas disease should be the initial step in its development. [ABSTRACT FROM AUTHOR]

The hematophagous common bed bug, Cimex lectularius, is not known to transmit human pathogens outside laboratory settings, having evolved various immune defense mechanisms including the expression of antimicrobial peptides (AMPs). We unveil three novel prolixicin AMPs in bed bugs, exhibiting strong homology to the prolixicin of kissing bugs, Rhodnius prolixus, and to diptericin/attacin AMPs. We demonstrate for the first time sex-specific and immune mode-specific upregulation of these prolixicins in immune organs, the midgut and rest of body, following injection and ingestion of Gr+ (Bacillus subtilis) and Gr– (Escherichia coli) bacteria. Synthetic CL-prolixicin2 significantly inhibited growth of E. coli strains and killed or impeded Trypanosoma cruzi, the Chagas disease agent. Our findings suggest that prolixicins are regulated by both IMD and Toll immune pathways, supporting cross-talk and blurred functional differentiation between major immune pathways. The efficacy of CL-prolixicin2 against T. cruzi underscores the potential of AMPs in Chagas disease management. [ABSTRACT FROM AUTHOR]

Triatomines are haematophagous insects, some species are vectors of Trypanosoma cruzi, the aetiological agent of Chagas disease. The main strategy for interrupting T. cruzi transmission is to avoid contact of the vector populations with humans. Volatiles from commercial essential oils are excellent candidates to serve as repellents of kissing bugs. We used an exposure device to assess the repellence effect of eight commercial essential oils on Triatoma pallidipennis. The most effective oils were blended and evaluated against T. infestans, T. pallidipennis and Rhodnius prolixus. The blend was also evaluated on parasitised T. pallidipennis. Data were compared with the commercial repellent NN‐diethyl‐3‐methylbenzamide. We recorded the time the insects spent in the proximity of the host and determined if any of the evaluated oils served as kissing bug repellent. We found commercial essential oils and a blend that significantly reduced the time spent in the proximity of the host. The blend was effective for use by human males and females, repelling infected and non‐infected insects. The study of essential oils as repellents of blood‐sucking disease‐vector insects could shed light on the development of new control strategies. [ABSTRACT FROM AUTHOR]

Chagas disease is a complex clinical entity caused by a protozoan parasite, Trypanosoma cruzi, transmitted by the bite of infected triatomines. The objective of this study was to establish the distribution of vector species of T. cruzi according to all the geopolitical regions of Ecuador. This narrative review was conducted from December 2022 to July 2023 by searching the following databases: PubMed, Elsevier, Google Scholar, Scielo, Latindex, and Dialnet. Also, websites of international and national health organizations: WHO and PAHO, Epidemiological Gazette of Ecuador, SIVE-ALERTA, Ministry of Public Health of Ecuador, and national repositories of theses generated by Ecuadorian universities. In the Coastal region, T. dimidiata was found as the predominant vector (83%), followed by Panstrongylus howardi, P. chinai and P. geniculatus, all with the same percentage of circulation (33%) and Rhodnius ecuadoriensis (17%). In the Andean region, the most important species was R. ecuadoriensis in the Province of Loja (59%). The province of Orellana (Amazon region) had the highest value of R=0.471 and greater species diversity (P. geniculatus, P. lignarius, R. robustus, R. pictipes, R. pallences, R. barreti, E. cuspidatus, E. mucronatu). Currently, the circulation of 4 genera and 17 species of triatomines is reported in Ecuador. It is necessary to expand the collection sites in different regions to update the geographical distribution of triatomine species circulating in Ecuadorian territory. [ABSTRACT FROM AUTHOR]

Background: During its life cycle, the human pathogen Trypanosoma cruzi must quickly adapt to different environments, in which the variation in the gene expression of the regulatory U-rich RNA-binding protein 1 (TcUBP1) plays a crucial role. We have previously demonstrated that the overexpression of TcUBP1 in insect-dwelling epimastigotes orchestrates an RNA regulon to promote differentiation to infective forms. Methods: In an attempt to generate TcUBP1 knockout parasites by using CRISPR-Cas9 technology, in the present study, we obtained a variant transcript that encodes a protein with 95% overall identity and a modified N-terminal sequence. The expression of this mutant protein, named TcUBP1mut, was notably reduced compared to that of the endogenous form found in normal cells. TcUBP1mut-knockdown epimastigotes exhibited normal growth and differentiation into infective metacyclic trypomastigotes and were capable of infecting mammalian cells. Results: We analyzed the RNA-Seq expression profiles of these parasites and identified 276 up- and 426 downregulated genes with respect to the wildtype control sample. RNA-Seq comparison across distinct developmental stages revealed that the transcriptomic profile of these TcUBP1mut-knockdown epimastigotes significantly differs not only from that of epimastigotes in the stationary phase but also from the gene expression landscape characteristic of infective forms. This is both contrary to and consistent with the results of our recent study involving TcUBP1-overexpressing cells. Conclusion: Together, our findings demonstrate that the genes exhibiting opposite changes under overexpression and knockdown conditions unveil key mRNA targets regulated by TcUBP1. These mostly encompass transcripts that encode for trypomastigote-specific surface glycoproteins and ribosomal proteins, supporting a role for TcUBP1 in determining the molecular characteristics of the infective stage. Author summary: In the intriguing world of Trypanosoma cruzi, the parasite causing Chagas disease in humans, a key factor known as TcUBP1 helps the pathogen navigate its different life stages. This microorganism undergoes a complex life cycle in which it alternates between a triatomine bug ("kissing bug") and a mammalian host. Our research demonstrated that increasing TcUBP1 levels in insect-dwelling forms prompts a gene expression pattern akin to infective forms, enhancing their ability to infect. Attempts to turn off TcUBP1 through gene editing resulted in TcUBP1mut, a variant with reduced expression closely resembling the native protein. TcUBP1mut cells exhibited distinct gene expression profiles compared to infective forms, according to the results of RNA-Seq analysis. This study corroborates our earlier findings on TcUBP1 overexpression, pinpointing genes with opposing expression patterns in both scenarios. These affected genes govern the production of infective-specific glycoproteins and ribosomal proteins, offering valuable insights into TcUBP1's regulatory role and unraveling mRNA targets crucial for parasite differentiation and infectivity. [ABSTRACT FROM AUTHOR]

Background: Triatoma infestans, Triatoma brasiliensis, Triatoma pseudomaculata and Rhodnius prolixus are vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. Chickens serve as an important blood food source for triatomines. This study aimed to assess the insecticidal activity of fluralaner (Exzolt®) administered to chickens against triatomines (R. prolixus, T. infestans, T. brasiliensis and T. pseudomaculata). Methods: Twelve non-breed chickens (Gallus gallus domesticus) were randomized based on weight into three groups: negative control (n = 4); a single dose of 0.5 mg/kg fluralaner (Exzolt®) (n = 4); two doses of 0.5 mg/kg fluralaner (Exzolt®) (n = 4). Nymphs of 3rd, 4th and 5th instars of R. prolixus, T. infestans, T. brasiliensis and T. pseudomaculata (all n = 10) were allowed to feed on chickens before treatment, and at intervals of 1, 7, 14, 21, 28, 35 and 56 days after treatment, with insect mortality determined. Results: Treatment with two doses of fluralaner showed higher insecticidal efficacy against R. prolixus, T. infestans and T. brasiliensis compared to the single-dose treatment. Similar insecticidal efficacy was observed for T. pseudomaculata for one and two doses of fluralaner. Insecticidal activity of fluralaner (Exzolt®) against triatomine bugs was noted up to 21 and 28 days after treatment with one and two doses of fluralaner, respectively. Conclusions: The results demonstrate that treatment of chickens with fluralaner (Exzolt®) induces insecticidal activity against triatomines for up to 28 days post-treatment, suggesting its potential use as a control strategy for Chagas disease in endemic areas. [ABSTRACT FROM AUTHOR]

We report Triatominae species Panstrongylus rufotuberculatus (Champion, 1899) for the first time in Belize. The specimen was collected in Cayo District, Belize in 2003 and later discovered in 2023 in a research collection. The distribution of P. rufotuberculatus spans Mexico to Argentina, and Belize lies within this range. This finding represents the fifth triatomine species reported in Belize, but only two species, Triatoma dimidata Latreille, 1811 and T. mopan Dorn et al., 2018, have been reported more than once. More research is needed to fully understand Triatominae biodiversity in Belize. [ABSTRACT FROM AUTHOR]

This review summarizes the interactions between Trypanosoma cruzi, the etiologic agent of Chagas disease, its vectors, triatomines, and the diverse intestinal microbiota of triatomines, which includes mutualistic symbionts, and highlights open questions. T. cruzi strains show great biological heterogeneity in their development and their interactions. Triatomines differ from other important vectors of diseases in their ontogeny and the enzymes used to digest blood. Many different bacteria colonize the intestinal tract of triatomines, but only Actinomycetales have been identified as mutualistic symbionts. Effects of the vector on T. cruzi are indicated by differences in the ability of T. cruzi to establish in the triatomines and in colonization peculiarities, i.e., proliferation mainly in the posterior midgut and rectum and preferential transformation into infectious metacyclic trypomastigotes in the rectum. In addition, certain forms of T. cruzi develop after feeding and during starvation of triatomines. Negative effects of T. cruzi on the triatomine vectors appear to be particularly evident when the triatomines are stressed and depend on the T. cruzi strain. Effects on the intestinal immunity of the triatomines are induced by ingested blood-stage trypomastigotes of T. cruzi and affect the populations of many non-symbiotic intestinal bacteria, but not all and not the mutualistic symbionts. After the knockdown of antimicrobial peptides, the number of non-symbiotic bacteria increases and the number of T. cruzi decreases. Presumably, in long-term infections, intestinal immunity is suppressed, which supports the growth of specific bacteria, depending on the strain of T. cruzi. These interactions may provide an approach to disrupt T. cruzi transmission. [ABSTRACT FROM AUTHOR]

Background: Triatoma garciabesi and T. guasayana are considered secondary vectors of Trypanosoma cruzi and frequently invade rural houses in central Argentina. Wing and head structures determine the ability of triatomines to disperse. Environmental changes exert selective pressures on populations of both species, promoting changes in these structures that could have consequences for flight dispersal. The aim of this study was to investigate the relationship between a gradient of anthropization and phenotypic plasticity in flight-related traits. Methods: The research was carried out in Cruz del Eje and Ischilín departments (Córdoba, Argentina) and included 423 individuals of the two species of triatomines. To measure the degree of anthropization, a thematic map was constructed using supervised classification, from which seven landscapes were selected, and nine landscape metrics were extracted and used in a hierarchical analysis. To determine the flight capacity and the invasion of dwellings at different levels of anthropization for both species, entomological indices were calculated. Digital images of the body, head and wings were used to measure linear and geometric morphometric variables related to flight dispersion. One-way ANOVA and canonical variate analysis (CVA) were used to analyze differences in size and shape between levels of anthropization. Procrustes variance of shape was calculated to analyze differences in phenotypic variation in heads and wings. Results: Hierarchical analysis was used to classify the landscapes into three levels of anthropization: high, intermediate and low. The dispersal index for both species yielded similar results across the anthropization gradient. However, in less anthropized landscapes, the density index was higher for T. garciabesi. Additionally, in highly anthropized landscapes, females and males of both species exhibited reduced numbers. Regarding phenotypic changes, the size of body, head and wings of T. garciabesi captured in the most anthropized landscapes was greater than for those captured in less anthropized landscapes. No differences in body size were observed in T. guasayana collected in the different landscapes. However, males from highly anthropized landscapes had smaller heads and wings than those captured in less anthropized landscapes. Both wing and head shapes varied between less and more anthropogenic environments in both species. Conclusions: Results of the study indicate that the flight-dispersal characteristics of T. garciabesi and T. guasayana changed in response to varying degrees of anthropization. [ABSTRACT FROM AUTHOR]

In the subfamily Triatominae, the genus Rhodnius is one of the most studied, not only because of its epidemiological importance, but also because of the difficulty in differentiating its species. Currently, one of the strategies to control Chagas disease, besides other initiatives such as the analysis of donated blood, is focused on fighting the vector. Correctly identifying triatomines is essential for the entomoepidemiological surveillance of Chagas disease. The objective of the present work was to compare the species of the R. prolixus complex using geometric morphometry of hemelytra and heads to evaluate the patterns of intraspecific and interspecific allometry and their taxonomic implications. This method can help in the diagnosis of close species, whose morphological characteristics are insufficient for correct identification. Specimens from five different collections were used, covering the species included in the R. prolixus complex (R. barretti, R. dalessandroi, R. domesticus, R. marabaensis, R. milesi, R. montenegrensis, R. nasutus, R. neglectus, R. neivai, R. prolixus and R. robustus). Morphometric analyses indicated that the hemelytra are not structures with good resolution for separating species and, for this reason, the use of the heads proved to be more adequate for this group (thus allowing differentiation of all species of the R. prolixus complex). The results suggest that R. milesi is a variant of R. neglectus and confirms that R. prolixus and R. robustus are distinct species. Furthermore, we propose the creation of the R. neivai complex comprising R. domesticus and R. neivai. [ABSTRACT FROM AUTHOR]

Triatomines (Hemiptera: Heteroptera: Reduviidae), commonly known as conenose or kissing bugs, includes species of outstanding medical importance given their role as vectors of the protozoan parasite Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae), the aetiological agent of Chagas disease. Herein, we present an updated review of the chemical ecology of triatomines, with special reference to molecules involved in the communication of these insects. Infochemicals, including hormones and semiochemicals (pheromones and allelochemicals), have a pivotal role in mediating information and shaping interactions within and between triatomines, during distinct behavioural contexts. We analyse the new findings about the chemical composition of alarm, aggregation and sex pheromones, as well as on cuticular hydrocarbons, host attractants and repellents. We also discuss how triatomine hormones may serve as communication signals and highlight the importance of the reverse chemical ecology approach in studying the complex chemoecology of these arthropod vectors. In the final section, we outline how knowledge about triatomine chemical ecology can be used for implementing real-world control operations with proven epidemiological impact. [ABSTRACT FROM AUTHOR]

Trypanosoma cruzi is the etiologic agent of Chagas disease. This flagellated protozoan is transmitted to humans as well as different species of domestic and wild animals via vectors from the Reduviidae family (known as "kissing bugs"). Despite the fact that hundreds of species of wild mammals are part of the reservoir system, the morphological changes and clinical manifestations resulting from the pathogenesis of the infection have been largely neglected. The aim of this review is to systematically compile the available information regarding clinicopathological alterations in wild mammals due to natural infection by T. cruzi. Information was obtained from six online bibliographic data search platforms, resulting in the identification of 29 publications that met the inclusion criteria. Mortality was the most common clinical manifestation, cardiac damage was the main finding at necropsy, and lymphoplasmacytic inflammation was the most frequent microscopic injury. Thus, regardless of its role as a reservoir, T. cruzi has the potential to affect the health status of wild mammals, a situation that highlights the need for further research to analyze, measure, and compare its effects at both the individual and population levels. [ABSTRACT FROM AUTHOR]

Background: Chagas disease, affecting approximately eight million individuals in tropical regions, is primarily transmitted by vectors. Rhodnius prolixus, a triatomine vector, commonly inhabits in ecotopes with diverse palm tree species, creating optimal conditions for vector proliferation. This study aims to explore the transmission ecology of Trypanosoma cruzi, the causative parasite of Chagas disease, by investigating the feeding patterns and natural infection rates of R. prolixus specimens collected from various wild palm species in the Colombian Orinoco region. Materials and methods: To achieve this objective, we sampled 35 individuals from three palm species (Attalea butyracea, Acrocomia aculeata, and Mauritia flexuosa) in a riparian forest in the Casanare department of eastern Colombia, totaling 105 sampled palm trees. DNA was extracted and analyzed from 115 R. prolixus specimens at different developmental stages using quantitative PCR (qPCR) for T. cruzi detection and identification of discrete typing units. Feeding preferences were determined by sequencing the 12S rRNA gene amplicon through next-generation sequencing. Results: A total of 676 R. prolixus specimens were collected from the sampled palms. The study revealed variation in population densities and developmental stages of R. prolixus among palm tree species, with higher densities observed in A. butyracea and lower densities in M. flexuosa. TcI was the exclusive T. cruzi discrete typing unit (DTU) found, with infection frequency positively correlated with R. prolixus abundance. Insects captured in A. butyracea exhibited higher abundance and infection rates than those from other palm species. The feeding sources comprised 13 mammal species, showing no significant differences between palm species in terms of blood sources. However, Didelphis marsupialis and Homo sapiens were present in all examined R. prolixus, and Dasypus novemcinctus was found in 89.47% of the insects. Conclusion: This study highlights the significance of wild palms, particularly A. butyracea, as a substantial risk factor for T. cruzi transmission to humans in these environments. High population densities and infection rates of R. prolixus were observed in each examined palm tree species. Author summary: Previous studies on Chagas disease in the Orinoco region primarily focused on domestic and peri-domestic areas of rural residences. However, to fully grasp the dynamics of T. cruzi transmission from natural, preserved areas to humans, it is crucial to comprehend the habitats and food resources that kissing bugs encounter in their natural distribution zones. In this study, we delved into both the habitat conditions and the food sources available on wild palms in the eastern plains region of Colombia, with the aim of understanding the establishment of the Chagas disease vector. Notably, our findings revealed that the studied kissing bugs fed on both wild and domestic animals, as well as humans, across all stages of their development. Furthermore, this research identified differences in the structural physiognomy of wild palms directly linked to the establishment of bug colonies. This knowledge enhances our understanding of the role of wild habitats in the dynamics of T. cruzi transmission in endemic areas. [ABSTRACT FROM AUTHOR]

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi transmitted by blood-sucking insects of the subfamily Triatominae, is a major neglected tropical disease affecting 6 to 7 million of people worldwide. Rhodnius prolixus, one of the most important vectors of Chagas disease in Latin America, is known to be highly sensitive to environmental factors, including temperature. This study aimed to investigate the effects of different temperatures on R. prolixus development and life-cycle, its relationship with T. cruzi, and to gather information about the nutritional habits and energy consumption of R. prolixus. We exposed uninfected and infected R. prolixus to four different temperatures ranging from 24°C to 30°C, and monitored their survival, developmental rate, body and blood meal masses, urine production, and the temporal dynamics of parasite concentration in the excreted urine of the triatomines over the course of their development. Our results demonstrate that temperature significantly impacts R. prolixus development, life-cycle and their relationship with T. cruzi, as R. prolixus exposed to higher temperatures had a shorter developmental time and a higher mortality rate compared to those exposed to lower temperatures, as well as a lower ability to retain weight between blood meals. Infection also decreased the capacity of the triatomines to retain weight gained by blood-feeding to the next developmental stage, and this effect was proportional to parasite concentration in excreted urine. We also showed that T. cruzi multiplication varied depending on temperature, with the lowest temperature having the lowest parasite load. Our findings provide important insights into the potential impact of climate change on the epidemiology of Chagas disease, and can contribute to efforts to model the future distribution of this disease. Our study also raises new questions, highlighting the need for further research in order to understand the complex interactions between temperature, vector biology, and parasite transmission. Author summary: Chagas disease, caused by the parasite Trypanosoma cruzi and transmitted by blood-sucking kissing bugs, is a major neglected tropical disease affecting millions of people worldwide. The insect vector Rhodnius prolixus is highly sensitive to environmental factors, including temperature. In this study, we investigated the effects of different temperatures on R. prolixus and its interaction with T. cruzi, as well as the nutritional habits and energy consumption of the vector. We exposed uninfected and infected insects to various temperatures, and monitored their survival, development, body and blood meal weights, urine production, and T. cruzi infection over their lifespan. Our results revealed that temperature significantly influenced R. prolixus development, life-cycle, and its interaction with T. cruzi. Insects exposed to higher temperatures had shorter development time, increased mortality, and reduced ability to maintain weight. Infection further compromised the ability of the triatomines to retain weight gained by blood-feeding, and this effect correlated with parasite load. Additionally, T. cruzi multiplication varied with temperature, with lower temperatures associated with lower parasite concentration. Our findings have important implications for understanding the impact of climate change on Chagas disease epidemiology and contribute to modeling its future spread. [ABSTRACT FROM AUTHOR]

Triatomines are the vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. The study aimed to evaluate the association between sociodemographic and environmental factors, and changes in land use and cover, with the occurrence and abundance of triatomines by census sectors in an endemic municipality of northern Minas Gerais, Brazil. The study was conducted in Montes Claros, located in the north of Minas Gerais, Brazil. The entomological data used in the study were collected by active surveillance in the rural area from 2015 to 2019 and by passive surveillance in the urban area from 2009 to 2019. Data on sociodemographic and environmental factors and changes in land use and land cover were obtained from the urban and rural census sectors. A total of 1404 triatomines, belonging to eight species, were captured in domiciles in the rural area (2015–2019) and 277 triatomines in domiciles in the urban area (2009–2019) of the municipality of Montes Claros. The variables the number of domiciles, household economic income, pavement, NDVI, deforestation, unchanged, and anthropic proved to be positively associated with the occurrence and/or number of triatomines in census sectors, within the models. The occurrence of triatomines in the domestic environment of the municipality of Montes Claros should be considered a public health problem, as it suggests a potential risk of establishment and transmission of T. cruzi to domestic animals, farm animals, and humans. [ABSTRACT FROM AUTHOR]

Background: In the Amazon region, several species of triatomines occur in the natural environments. Among them, species of the genus Rhodnius are a risk to human populations due to their high rates of infection with Trypanosoma cruzi. The aim of this study was to identify the T. cruzi genotypes in Rhodnius specimens and their relationship with sylvatic hosts from different environments in the Brazilian Amazon. Methods: A total of 492 triatomines were collected from the municipalities of Monte Negro, Rondônia state, and Humaitá, Amazonas state, 382 of them being nymphs and 110 adults. Genotyping of T. cruzi in six discrete typing units (DTUs) was performed using conventional multilocus PCR. The triatomines that were positive for T. cruzi and engorged with blood were also targeted for amplification of the cytochrome B (cytB) gene to identify bloodmeal sources. Results: Of the 162 positive samples, the identified DTUs were TcI (87.65%) and TcIV (12.35%). It was observed that 102 specimens were engorged with a variety of bloodmeals. Triatomines infected with TcI were associated with DNA of all identified vertebrates, except Plecturocebus brunneus. TcIV was detected in triatomines that fed on Coendou prehensilis, Didelphis marsupialis, Mabuya nigropunctata, P. brunneus, Pithecia irrorata, Sapajus apella, and Tamandua tetradactyla. Conclusion: Results highlight the need to understand the patterns of T. cruzi genotypes in Rhodnius spp. and their association with sylvatic hosts to better elucidate their role in the transmission of Chagas disease in the Amazon region. [ABSTRACT FROM AUTHOR]

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Chagas disease is a zoonosis caused by the protozoan parasite Trypanosoma cruzi and transmitted by a broad range of blood-sucking triatomine species. Recently, it is recognized that the parasite can also be transmitted by host ingestion. In this paper, we propose a Chagas disease model incorporating two transmission routes of biting-defecation and host predation between vectors and hosts with Holling II functional response. The basic reproduction number Rv of triatomine population and basic reproduction numbers Ro of disease population are derived analytically, and it is shown that they are insufficient to serve as threshold quantities to determine dynamics of the model. Our results have revealed the phenomenon of bistability, with backward and forward bifurcations. Specifically, if Rv > 1, the dynamic is rather simple, namely, the disease-free equilibrium is globally asymptotically stable as Ro < 1 and a unique endemic equilibrium is globally asymptotically stable as Ro > 1. However, if Rv < 1, there exists a backward bifurcation with one unstable and one stable positive vector equilibria, and bistability phenomenon occurs, revealing that different initial conditions may lead to disease extinction or persistence even if the corresponding Ro > 1. In conclusion, predation transmission in general reduces the risk of Chagas disease, whilst it makes the complexity of Chagas disease transmission, requiring an integrated strategy for the prevention and control of Chagas disease. [ABSTRACT FROM AUTHOR]

BACKGROUND: The southwestern United States is home to a variety of arthropods including Turkestan cockroaches, Blatta lateralis (Walker); hematophagous kissing bugs, Tritoma rubida (Uhler); and Arizona bark scorpions, Centruroides sculpturatus Ewing. These arthropods cause medical concern when they become established around homes and/or invade indoors. Traditionally, the management of these pests has relied primarily on the use of chemical insecticides; however, they offer poor prospects for control owing to their lack of efficacy as well as the effects of insecticides on humans and the environment. Botanical repellents are an option that has not been fully investigated for the management of these pests. Here, we investigated the behavioral responses of common urban pests of the southwestern USA to recently discovered coconut fatty acids (CFAs), to establish the potential use of these compounds as repellents. RESULTS: Fresh residues of CFA mixture (CFAm) and their constituents caprylic acid, capric acid, capric acid methyl ester, lauric acid, and lauric acid methyl ester, tested at a concentration of 1 mg cm−2, strongly repelled all arthropods. The repellent activity of CFAm lasted for at least 7 days, and the addition of lavender oil, used as an odor‐masking agent, did not decrease this effect. Concentrations of CFAm ten times lower (0.1 mg cm−2) still repelled Turkestan cockroaches, and concentrations 100 times lower (0.01 mg cm−2) repelled T. rubida and scorpions. CONCLUSIONS: CFAm and some of their constituents are efficacious, economical, and logistically feasible for inclusion in integrated pest management programs for these important urban pests of the southwestern USA. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Chagas disease is one of the most important public health problems in America, involving triatomines (Hemiptera: Reduviidae: Triatominae) in the vectorial transmission of Trypanosoma cruzi (Protista: Kinetoplastea: Trypanosomatidae). In Argentina, 15 species of triatomines are distributed, of which seven are the most common in the domicile and peridomicile, while the rest are mainly associated with wild environments. Due to the lack of updated data of geographic distribution, the GeoVin Project arises to provide not only a triatomine digital tool of triatomine notification, but also resources with information about Chagas and triatomine vectors. The aim of this paper is to present, describe and highlight the progress of the project, emphasizing the principles of participatory science and entomological surveillance. So far, more than 2,300 web visits have been recorded and the application has been downloaded over 3,400 times. The contribution of the project in articulating with the corresponding government health agencies and the immediacy of the interaction with the community are key elements for the project success. At the same time, the information collected is a constant input for updating the geographical distributions of Argentinian triatomines. [ABSTRACT FROM AUTHOR]

Simple Summary: This study analyzed microsatellite distribution in the holocentric chromosomes of Triatominae, Chagas disease vectors. Using a non-denaturing FISH technique, 16 microsatellites were examined across 25 species from the Triatomini and Rhodniini tribes. Three hybridization patterns emerged: strong signals in specific regions, dispersed signals based on microsatellite abundance and the absence of signals in certain regions or chromosomes. Rhodniini had weak and scattered signals, indicating low microsatellite abundance, while Triatomini showed diverse and abundant patterns, suggesting their significance in genomes. Particularly, all Triatomini species exhibited a high abundance of GATA repeats in the Y chromosome, unlike Rhodniini. This suggests the ancestral trait is specific to Triatomini. The study provides insights into microsatellite composition and distribution in Triatominae genomes, shedding light on their evolutionary processes and relationships with other reduviid groups. This study focused on analyzing the distribution of microsatellites in holocentric chromosomes of the Triatominae subfamily, insect vectors of Chagas disease. We employed a non-denaturing FISH technique to determine the chromosomal distribution of sixteen microsatellites across twenty-five triatomine species, involving five genera from the two principal tribes: Triatomini and Rhodniini. Three main hybridization patterns were identified: strong signals in specific chromosomal regions, dispersed signals dependent on microsatellite abundance and the absence of signals in certain chromosomal regions or entire chromosomes. Significant variations in hybridization patterns were observed between Rhodniini and Triatomini species. Rhodniini species displayed weak and scattered hybridization signals, indicating a low abundance of microsatellites in their genomes. In contrast, Triatomini species exhibited diverse and abundant hybridization patterns, suggesting that microsatellites are a significant repetitive component in their genomes. One particularly interesting finding was the high abundance of GATA repeats, and to a lesser extent AG repeats, in the Y chromosome of all analyzed Triatomini species. In contrast, the Y chromosome of Rhodniini species did not show enrichment in GATA and AG repeats. This suggests that the richness of GATA repeats on the Y chromosome likely represents an ancestral trait specific to the Triatomini tribe. Furthermore, this information can be used to elucidate the evolutionary relationships between Triatomini and other groups of reduviids, contributing to the understanding of the subfamily's origin. Overall, this study provides a comprehensive understanding of the composition and distribution of microsatellites within Triatominae genomes, shedding light on their significance in the evolutionary processes of these species. [ABSTRACT FROM AUTHOR]

Chagas disease is caused by the hemoflagellate protozoan Trypanosoma cruzi. The main transmission mechanism for the parasite in endemic areas is contact with the feces of an infected triatomine bug. Part of the life cycle of T. cruzi occurs in the digestive tract of triatomines, where vector and parasite engage in a close interaction at a proteomic–molecular level. This interaction triggers replication and differentiation processes in the parasite that can affect its infectivity for the vertebrate host. With the aim of compiling and analyzing information from indexed publications on transcripts, proteins, and glycoproteins in the guts of fasting, fed, and T. cruzi-infected triatomines in the period 2000–2022, a systematic review was conducted following the PRISMA guidelines. Fifty-five original research articles retrieved from PubMed and ScienceDirect were selected; forty-four papers reported 1–26,946 transcripts, and twenty-one studies described 1–2603 peptides/proteins. [ABSTRACT FROM AUTHOR]

Simple Summary: Zoos help to rescue, rehabilitate, and care for wildlife. Approximately fifteen years ago, the Alpine ibex (Capra ibex) was successfully reintroduced into the Alps. There are at least 17 zoos throughout Europe that keep Alpine ibexes in captivity. To ensure success, the staff must understand the animal's specific requirements and provide leading managers and researchers to investigate strategies such as feed quality control, successful reproduction, and appropriate social group structure. The animal welfare strategy is an important factor for success. Appropriate and stress-free animal capture and sampling methods are especially important. Non-invasive sampling methods are increasingly being used in veterinary practice. Cortisol (C) concentrations can be measured in various matrices, such as saliva, hair, and faeces. Blood collection using venipuncture, which is stressful, can be replaced by collection with kissing bugs (Triatomines) or medicinal leeches (Hirudo medicinalis). In this article, C concentrations in different matrices were compared in Alpine ibexes at the zoo. Differences according to the sex, age, and season of sampling were also compared. The usefulness of blood collection using venipuncture versus kissing bugs or medicinal leeches and the collection of saliva, faeces, hair, urine, and tears for measuring "immunoreactive" C (iC) concentration in Alpine ibexes was verified using commercial enzyme immunoassays. The mean value of serum C was highest in serum collected using venipuncture and lowest in serums collected using kissing bugs. Statistically significant differences were observed between venipuncture and kissing bugs and between leeches and kissing bugs. However, no statistically significant difference was found in C concentrations between samples collected with venipuncture and those collected with leeches. The highest mean value of C concentration was measured in serum (all three methods), followed by that in hair and faeces, and the lowest mean value was found in saliva. Statistically significant differences were found between saliva and faeces samples and between saliva and hair samples. The difference between the concentrations for faeces and hair was not statistically significant. A significant difference in C concentration between males and females was found in saliva. A significant difference in C concentration among different ages was measured in serum obtained using venipuncture in all three groups and in faeces between the groups older than ten years and younger than 10 months. Highly significant differences in C concentrations were also found between hair sampled in summer and hair sampled in autumn. Collecting tear and urine samples is a laborious procedure and is therefore less acceptable for C determination. Due to the small number of samples, statistical values are not given for these two matrices. [ABSTRACT FROM AUTHOR]

Background: Triatomines are blood-sucking insects capable of transmitting Trypanosoma cruzi, the parasite that causes Chagas disease in humans. Vectorial transmission entails an infected triatomine feeding on a vertebrate host, release of triatomine infective dejections, and host infection by the entry of parasites through mucous membranes, skin abrasions, or the biting site; therefore, transmission to humans is related to the triatomine–human contact. In this cross-sectional study, we evaluated whether humans were detected in the diet of three sylvatic triatomine species (Mepraia parapatrica, Mepraia spinolai, and Triatoma infestans) present in the semiarid–Mediterranean ecosystem of Chile. Methods: We used triatomines collected from 32 sites across 1100 km, with an overall T. cruzi infection frequency of 47.1% (N = 4287 total specimens) by conventional PCR or qPCR. First, we amplified the vertebrate cytochrome b gene (cytb) from all DNA samples obtained from triatomine intestinal contents. Then, we sequenced cytb-positive PCR products in pools of 10–20 triatomines each, grouped by site. The filtered sequences were grouped into amplicon sequence variants (ASVs) with a minimum abundance of 100 reads. ASVs were identified by selecting the best BLASTn match against the NCBI nucleotide database. Results: Overall, 16 mammal (including human), 14 bird, and seven reptile species were identified in the diet of sylvatic triatomines. Humans were part of the diet of all analyzed triatomine species, and it was detected in 19 sites representing 12.19% of the sequences. Conclusions: Sylvatic triatomine species from Chile feed on a variety of vertebrate species; many of them are detected here for the first time in their diet. Our results highlight that the sylvatic triatomine–human contact is noteworthy. Education must be enforced for local inhabitants, workers, and tourists arriving in endemic areas to avoid or minimize the risk of exposure to Chagas disease vectors. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Immunogenic Salivary Proteins of Triatoma infestans: Development of a Recombinant Antigen for the Detection of Low-Level Infestation of Triatomines." The concerns raised about Figure 1 were addressed by the author, who stated that the concerns were artifacts generated through reproduction of the image and not relevant to the interpretation of the figure. The PLOS Neglected Tropical Diseases Editors consider these concerns to be resolved. The underlying data from the original experiments were provided and support the conclusions reported in the article. The document also includes an updated version of Figure 3 and states that the remainder of the data is available from the author. [Extracted from the article]

Entomological surveillance is essential for the control of triatomines and the prevention of Trypanosoma cruzi infection in humans and domestic animals. Thus, the objective of this study was to evaluate entomological indicators and triatomine control during the period from 2005 to 2015 in an endemic area in the state of Rio Grande do Norte, Brazil. This observational and retrospective study was developed based on data analysis related to active entomological surveillance activities and chemical control of infested housing units (HU) in the Agreste mesoregion of the state of Rio Grande do Norte, Brazil, in the period between 2005 to 2015. The quantitative analysis of housing units surveyed for entomological indicators was performed by linear regression of random effects (p < 0.05). The effect of the number of HU surveyed on the entomological indicators was analyzed by fitting a linear random effects regression model and an increasing intradomiciliary colonization rate was significant. In the period evaluated 92,156 housing units were investigated and the presence of triatomines was reported in 4,639 (5.0%). A total of 4,653 specimens of triatomines were captured and the species recorded were Triatoma pseudomaculata (n = 1,775), Triatoma brasiliensis (n = 1,569), Rhodnius nasutus (n = 741) and Panstrongylus lutzi (n = 568), with an index of natural infection by T. cruzi of 2.2%. Only 53.1% of the infested HU were subjected to chemical control. Moreover, there was a decrease in the total number of HU surveyed over time associated with an increase in the index of intradomiciliary colonization (p = 0.004). These data demonstrated that entomological surveillance and control of vectors in the Agreste mesoregion of the state has been discontinued, emphasizing the need for more effective public policies to effectively control the vectors, in order to avoid the exposure of humans and domestic animals to the risk of T. cruzi infection. [ABSTRACT FROM AUTHOR]

To update a list of arthropod group-species, including triatomines, in the State of Sonora, northwestern Mexico, entomological surveys were done during the spring of 2022 in conserved areas of the state. Triatomines Triatoma rubida (Uhler) and T. sinaloensis Ryckman (Hemiptera: Reduviidae) were found living in nests of woodrats, Neotoma sp., and California roadrunners, Geococcyx californianus (Lesson). Because T. rubida is one of the main vectors of Chagas disease in North America, and T. sinaloensis has been found naturally infected with Trypanosoma cruzi Chagas, surveillance of the species should be essential for Chagas disease control programs in northwestern Mexico. [ABSTRACT FROM AUTHOR]

The present study, carried out in the municipality of Gentio do Ouro, Bahia, Brazil aimed to evaluate which wild mammals may be involved in the transmission of T. cruzi and which are the blood sources for triatomines collected in the study area. PCR analysis of 31 wild mammals captured revealed T. cruzi infection in 6.4% (2/31): one specimen of the opossum Didelphis albiventris (1/3) and one of the rodent Kerodon rupestris (1/5); despite being more frequent in the area, no specimen of the rodent Thrichomys sp. (0/23) was infected. A total of 169 triatomines were captured. The conclusive detection of food sources was possible only for Triatoma sherlocki Papa et al., 2002 (n = 56), with evidence for: K. rupestris (35.7%), Gallus (17.9%), D. albiventris (14.3%), Homo sapiens (14.3%), Tropidurus hispidus (7.1%), Leopardus geoffroyi (5.3%), Conepatus semistriatus (1.8%), Thrichomys inermis (1.8%) and Rattus norvegicus (1.8%). Triatomines of the species T. sherlocki showed food eclecticism, including feeding on humans, with some of them being captured at dwellings. These facts make this triatomine a potential link for the transmission of T. cruzi between wild and anthropic environments, highlighting a latent risk of the reemergence of Chagas disease outbreaks. [ABSTRACT FROM AUTHOR]

Chagas disease (CD) is a neglected illness affecting approximately seven million individuals, with vector transmission occurring via triatomine bugs. The Rhodniini tribe comprises 24 species, grouped into the Rhodnius and Psammolestes genera. Given the importance of accurately identifying CD vectors, the taxonomy of Psammolestes spp. was revisited using morphological and morphometric data. Specimens of P. tertius, P. coreodes, and P. arthuri were collected, and the morphological characteristics of the head, thorax, abdomen, and eggs were analyzed. Morphometric studies of eggs were also conducted. Dichotomous keys allowing for the differentiation of Psammolestes spp. were elaborated based on adult insect and egg morphological characteristics. Through these studies, it was possible to differentiate the three Psammolestes species and confirm that this genus should not be classified under the Rhodnius genus, contributing to Rhodniini taxonomy. [ABSTRACT FROM AUTHOR]

Simple Summary: Triatominae, commonly known as kissing bugs, are blood-feeding insects that can carry the parasite Trypanosoma cruzi to spread Chagas disease. In this study, we conducted a taxonomic review of Chinese triatomines, which involved describing two new species, Triatoma picta Zhao & Cai sp. nov. and T. atrata Zhao & Cai sp. nov. We also calculated the pairwise genetic distances of Triatoma and offered a key to species of Triatominae in China. This review may facilitate a better understanding of the diversity of Chinese kissing bugs. Triatominae, the only blood-sucking subfamily in Reduviidae, are the vectors of Chagas disease. The majority of them are distributed in the Americas, while the diversity in China has been underestimated, as only two species have been recorded. Here, we describe two new species from China, Triatoma picta Zhao & Cai sp. nov. and T. atrata Zhao & Cai sp. nov., and provide a redescription of T. sinica Hsiao, 1965, along with remarks on T. rubrofasciata (De Geer, 1773). To facilitate the identification, we include photos, especially of genitalia, as well as a distribution map and a key to Chinese triatomines. We calculated the pairwise genetic distances between 23 Triatoma species, which further supported the validity of these new species. We anticipate that our taxonomic review will be useful for identifying Chinese Triatominae. [ABSTRACT FROM AUTHOR]

Simple Summary: All 155 living species of triatomines are considered to be potential vectors of Chagas disease. Laboratory and field studies demonstrate that these insects are capable of crossing and producing hybrids. Hybrids of Triatoma spp. have a greater capacity and vectorial competence to acquire and transmit Trypanosoma cruzi than the parental species. Therefore, we conducted studies to assess whether the Rhodnius spp. and Psammolestes spp. that live in sympatry (if found in natural conditions) or allopatry (geographically isolated) are capable of producing hybrids. We observed that all cross species produce hybrid offspring in at least one direction. Although the vectorial capacity and competence of these insect vectors must be evaluated, we emphasize the importance of directing the monitoring activities of vector control programs toward possible natural hybridization events in the face of climatic and environmental changes. Chagas disease affects about eight million people. In view of the issues related to the influence of anthropogenic changes in the dynamics of the distribution and reproductive interaction of triatomines, we performed experimental crosses between species of the Rhodniini tribe in order to evaluate interspecific reproductive interactions and hybrid production capacity. Reciprocal crossing experiments were conducted among Rhodnius brethesi × R. pictipes, R. colombiensis × R. ecuadoriensis, R. neivai × R. prolixus, R. robustus × R. prolixus, R. montenegrensis × R. marabaensis; R. montenegrensis × R. robustus, R. prolixus × R. nasutus and R. neglectus × R. milesi. With the exception of crosses between R. pictipes ♀ × R. brethesi ♂, R. ecuadoriensis ♀ × R. colombiensis ♂ and R. prolixus ♀ × R. neivai ♂, all experimental crosses resulted in hybrids. Our results demonstrate that both allopatric and sympatric species produce hybrids, which can generate concern for public health agencies in the face of current anthropogenic events. Thus, we demonstrate that species of the Rhodniini tribe are capable of producing hybrids under laboratory conditions. These results are of great epidemiological importance and raise an important discussion about the influence of climatic and environmental interactions on Chagas disease dynamics. [ABSTRACT FROM AUTHOR]

Simple Summary: Triatominae (Hemiptera, Reduviidae) bugs are considered species of medical relevance because they are vectors of Chagas disease. In Mexico, most species of the Triatoma genus are distributed in the lowlands of the west of Mexico, including the Mexican Pacific coast. Here, we describe Triatoma yelapensis sp. nov. from the Pacific coast of Jalisco (Mexico). We provide statistical support for the morphological distinctiveness of the new species and an updated key of the genus Triatoma for species recorded in Mexico. Thirty-four species of Triatominae (Hemiptera, Reduviidae) are recorded in Mexico, Triatoma Laporte, 1832 the most speciose genus in this country. Here, we describe Triatoma yelapensis sp. nov. from the Pacific coast of Jalisco (Mexico). The most similar species to T. yelapensis sp. nov. is T. recurva (Stål, 1868), but they differ in head longitude, the proportion of labial segments, coloration pattern of corium and connexivum, spiracles location, and male genitalia. To provide statistical support for the morphological distinctiveness of the new species, we performed a geometric morphometric analysis of T. yelapensis sp. nov., T. dimidiata s.s. (Latreille, 1811), T. gerstaeckeri (Stål, 1859), and T. recurva (Stål, 1868), considering head morphology. We also provide an updated key of the genus Triatoma for species recorded in Mexico. [ABSTRACT FROM AUTHOR]

Simple Summary: The kissing bug, Rhodnius prolixus, is a blood-gorging insect that is medically important, being a principal vector of Trypanosoma cruzi, which causes Chagas disease. Understanding the reproductive biology of R. prolixus is, therefore, of some importance from a scientific perspective, but also in the medical context in order to control the spread of the disease. Here we show that the male reproductive system of R. prolixus is composed of muscular tissues performing contractions that aid in the transfer of sperm and other fluids into the female during mating. These contractions are further shown to be controlled by neuropeptides released by the nervous system that act on the receptors to either increase or inhibit the contractions. The male reproductive structures are, therefore, coordinated for successful copulation, whereby the transfer of sperm and fluid occurring during copulation is facilitated through a coordination of the contraction of the muscles within the male reproductive system. This study is critically important to provide novel options for pest management. The gross anatomy of the male reproductive structures and their associated musculature are described in the blood-gorging vector of Chagas disease, Rhodnius prolixus. The male reproductive system is composed of muscular tissues each performing contractions that aid in the movement of sperm out of the testis into the vas deferens, seminal vesicle and then into the ejaculatory duct, along with proteins and lipids from the transparent and opaque accessory glands. Phalloidin staining shows the various patterns of muscle fiber layers, from thin circular to more complex crisscross patterns, implying subtle differences in the form of the contractions and movement of each of the structures, allowing for waves of contractions or twisting patterns. The transcripts for the receptors for proctolin, myosuppressin (RhoprMS) and for the extended FMRFamides are expressed in the various regions of the reproductive system, and the nerve processes extending over the reproductive structures are positive for FMRFamide-like immunoreactivity, as are neurosecretory cells lying on the nerves. Proctolin and AKDNFIRFamide are strong stimulators for the frequency of the contractions, and RhoprMS can inhibit the proctolin-induced contractions. Taken together, this work implicates these two families of peptides in coordinating the male reproductive structures for the successful transfer of sperm and the associated accessory gland fluid to the female during copulation. [ABSTRACT FROM AUTHOR]

Simple Summary: Foci of Triatoma infestans were found in the states of Rio Grande do Sul and Bahia, Brazil. The objective of the present work is to evaluate the morphometric differences between populations of residual and wild focus of T. infestans through head geometric morphometry. It is possible to show significant morphometric differences between the studied populations. Furthermore, it is possible to establish a morphometric relationship between these populations and to list hypotheses about the distribution and maintenance of residual foci of T. infestans in Brazil. 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. [ABSTRACT FROM AUTHOR]

Several cytogenetic studies have already been performed in Triatominae, such that different karyotypes could be characterized (ranging from 2n = 21 to 25 chromosomes), being the changes in the number of chromosomes related mainly to fusion and fission events. These changes have been associated with reproductive isolation and speciation events in other insect groups. Thus, we evaluated whether different karyotypes could act in the reproductive isolation of triatomines and we analyzed how the events of karyotypic evolution occurred along the diversification of these vectors. For this, experimental crosses were carried out between triatomine species with different karyotypes. Furthermore, based on a phylogeny with 88 triatomine taxa (developed with different molecular markers), a reconstruction of ancestral karyotypes and of anagenetic and cladogenetic events related to karyotypic alterations was performed through the ChromoSSE chromosomal evolution model. All crosses performed did not result in hybrids (prezygotic isolation in both directions). Our modeling results suggest that during Triatominae diversification, at least nine cladogenetic events may be associated with karyotype change. Thus, we emphasize that these alterations in the number of chromosomes can act as a prezygotic barrier in Triatominae (karyotypic isolation), being important evolutionary events during the diversification of the species of Chagas disease vectors. [ABSTRACT FROM AUTHOR]

Background: Triatomine insects, vectors of the etiologic agent of Chagas disease (Trypanosoma cruzi), are challenging to locate in sylvatic habitats. Collection techniques used in the United States often rely on methods to intercept seasonally dispersing adults or on community scientists' encounters. Neither method is suited for detecting nest habitats likely to harbor triatomines, which is important for vector surveillance and control. Furthermore, manual inspection of suspected harborages is difficult and unlikely to reveal novel locations and host associations. Similar to a team that used a trained dog to detect sylvatic triatomines in Paraguay, we worked with a trained scent detection dog to detect triatomines in sylvatic locations across Texas. Principle methodology/Findings: Ziza, a 3-year-old German Shorthaired Pointer previously naturally infected with T. cruzi, was trained to detect triatomines. Over the course of 6 weeks in the fall of 2017, the dog and her handler searched at 17 sites across Texas. The dog detected 60 triatomines at 6 sites; an additional 50 triatomines were contemporaneously collected at 1 of these sites and 2 additional sites without the assistance of the dog. Approximately 0.98 triatomines per hour were found when only humans were conducting searches; when working with the dog, approximately 1.71 triatomines per hour were found. In total, 3 adults and 107 nymphs of four species (Triatoma gerstaeckeri, Triatoma protracta, Triatoma sanguisuga, and Triatoma indictiva) were collected. PCR testing of a subset revealed T. cruzi infection, including DTUs TcI and TcIV, in 27% of nymphs (n = 103) and 66% of adults (n = 3). Bloodmeal analysis of a subset of triatomines (n = 5) revealed feeding on Virginia opossum (Didelphis virginiana), Southern plains woodrat (Neotoma micropus), and eastern cottontail (Sylvilagus floridanus). Conclusion/Significance: A trained scent detection dog enhanced triatomine detections in sylvatic habitats. This approach is effective at detecting nidicolous triatomines. Control of sylvatic sources of triatomines is challenging, but this new knowledge of specific sylvatic habitats and key hosts may reveal opportunities for novel vector control methods to block the transmission of T. cruzi to humans and domestic animals. Author summary: Triatomine insects, also known as 'kissing bugs,' are vectors of Trypanosoma cruzi, the parasite that causes Chagas disease in humans, dogs, and other mammals. Triatomines are found throughout the Americas, but for many species, little is known about where these blood-sucking insects spend their early life stages. Knowing more is important to vector control initiatives aimed at preventing Chagas disease. Scent detection dogs have been trained to detect many pests, including one study in Paraguay of a dog trained to detect triatomines. In this study, we used a dog to detect triatomines in their natural environments throughout Texas. Over 6 weeks, the dog identified 60 triatomines at 6 different sites; an additional 50 triatomines were collected without the dog's assistance. More triatomines were collected per hour when the dog was searching when compared to only humans searching. Of all the triatomine nymphs collected, 27% were positive for T. cruzi, and bloodmeal analyses revealed kissing bugs had fed on Southern plains woodrat, opossum, and eastern cottontail. This study outlines a strategy that can be replicated in the United States to enhance the detection and control of habitats where triatomines spend their early life stages. [ABSTRACT FROM AUTHOR]

Objective. Systematize, evaluate and synthesize specific research for Mexico on the zoonosis caused by Trypanosoma cruzi, its vectors (Triatominae: Hemiptera: Reduviidae), and Chagas disease (CD). Materials and methods. Using PRISMA, original research was identified through four search engines, selected using inclusion criteria, assigned to 14 topic areas, and evaluated using technical criteria. Results. 1 410 records were identified and 659 (46.7%) were chosen for technical evaluation, of which 221 (15.7%) were rated as the highest quality. PubMed contributed 95% of the publications, while BibTri, Lilacs and Scielo contributed the remaining 5%. Publication rate was constant between 1950 and 1990, although there was an exponential increase from 1995 to 2020. Publication quality increased from 5.3% of registries in 1990 to 49.8% in 2020. Systemic, economic, anthropological and social aspects of CD in Mexico were the topics least published (8%). Conclusions. Despite the remarkable increase in knowledge generated in the last two decades in Mexico, this systematic review highlights evidence gaps fundamental for public healthcare policy to attend, prevent, and control CD in the country. [ABSTRACT FROM AUTHOR]

Triatomines display most of their activities during the night. Before sunrise, they search, select and occupy adequate shelters to stay during the photophase, avoiding exposure to diurnal predators. In this work, we first explored the interactions between individuals of the same or different species in the shelter selection process of Triatoma infestans (Klug 1834) and Rhodnius prolixus (Stål 1859). When two groups of insects (either of different nutritional status, nymphal instar or species) were released together over an experimental arena containing two identical shelters, all nymphs were distributed randomly, suggesting the absence of intra‐ and inters‐pecific interactions. Secondly, we analysed their preferences for particular features of shelters by releasing one group of insects (either T. infestans or R. prolixus) over an arena containing two different refuges. Nymphs exhibited preferences for darker shelters with a vertical orientation of its substrate and elevated from the ground, highlighting the importance of such features in a shelter selection context. We conclude that these species disregard the presence of other individuals but evaluate certain characteristics of the shelters to choose them. This information may contribute to understanding the colonization/recolonization dynamic processes of these Chagas disease vectors. [ABSTRACT FROM AUTHOR]

Simple Summary: Triatomines are hemimetabolous and hematophagous insect vectors of Trypanosoma cruzi, the parasite that causes Chagas disease. The life cycle of triatomines is composed of five nymphal stages and an adult stage. The wild kissing bug Mepraia spinolai is distributed in a vast area of the semiarid Mediterranean ecosystem of South America, characterized by strongly marked seasons. The population structure of this vector changes during the different seasons, suggesting its development is controlled under natural conditions. In this study, we performed a biological assay to study this vector development after two laboratory feedings. We collected nymphs, first to fourth instars, in eight M. spinolai populations during the transition of late fall to winter (cooling period) and spring (warming period) of three consecutive years. The gathered information with vectors molting twice suggests that development is differentially controlled in nymphs from first and fourth instars depending on the climatic period of collection. Additionally, T. cruzi infection changes development forward only in nymphs of second and fourth instars of the warming period. Our findings suggest that the effect of the climatic period and T. cruzi infection on the development of this vector species is a stage-dependent phenomenon. In this study, we evaluated the effect of the climatic season and infection by Trypanosoma cruzi, etiological agent of Chagas disease, on the molting capacity of the triatomine vector Mepraia spinolai endemic to Chile. We used wild-caught first-to-fourth instar nymphs during cooling (fall and winter) and warming (spring) periods. After capturing, nymphs were fed at the laboratory, and maintained under optimal rearing conditions. Feeding was repeated 40 days later. We followed-up the molting events on 709 nymphs, recording one, two or the absence of molts after two feeding opportunities. Within the same climatic period, only infected second- and fourth-instar nymphs from the warming period showed a larger proportion of double molting compared to uninfected nymphs. Regarding the climatic period, infected and uninfected first- and fourth-instar nymphs exhibited a larger proportion of double molting in the warming and cooling periods, respectively. The pattern of non-molting nymph occurrence suggests they probably reach diapause by environmental stochasticity. The effect of the climatic period and T. cruzi infection on the development of M. spinolai is an instar-dependent phenomenon, highlighting the occurrence of finely synchronized processes at different moments of the life cycle of such an hemimetabolous insect as triatomines. [ABSTRACT FROM AUTHOR]