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Triatomine bugs are vectors for the Trypanosoma cruzi Chagas parasites, the etiological agent for Chagas disease. This study evaluated 6 epidemiologically significant behaviors (development time, number of blood meals required for molting to the next instar, mortality rate, aggressiveness, feeding duration, and defecation delay) across 4 populations of Triatoma mexicana Herrich-Schaeffer (Heteroptera: Reduviidae), a major T. cruzi vector in Central Mexico. We collected triatomines from areas characterized by high (HP), medium (MP), medium-high (MHP), and low (LP) prevalence of human T. cruzi infection.The MHP population had the shortest development time, <290 days. Both the HP and MP populations required the most blood meals to molt to the next instar, with a median of 13. Mortality rates varied across all populations, ranging from 44% to 52%. All of the tested populations showed aggressive behavior during feeding. All populations shared similar feeding durations, with most exceeding 13 min and increasing with each instar. Quick defecation, during feeding, immediately after or less than 1 min after feeding, was observed in most nymphs (78%–90%) from the MP and MHP populations and adults (74%–92%) from HP, MP, and MHP populations.Though most parameters suggest a low potential for T. mexicana to transmit T. cruzi, unique feeding and defecation behaviors in 3 populations (excluding the LP group) could elevate their epidemiological importance.These population-specific differences may contribute to the varying prevalence rates of T. cruzi infection in areas where T. mexicana is found. Graphical Abstract

Triatomine vectors transmit Trypanosoma cruzi, the etiological agent of Chagas disease in humans. Transmission to humans typically occurs when contaminated triatomine feces come in contact with the bite site or mucosal membranes. In the Southern Cone of South America, where the highest burden of disease exists, Triatoma infestans is the principal vector for T. cruzi. Recent studies of other vector-borne illnesses have shown that arthropod microbiota influences the ability of infectious agents to colonize the insect vector and transmit to the human host. This has garnered attention as a potential control strategy against T. cruzi, as vector control is the main tool of Chagas disease prevention. Here we characterized the microbiota in T. infestans feces of both wild-caught and laboratory-reared insects and examined the relationship between microbial composition and T. cruzi infection using highly sensitive high-throughput sequencing technology to sequence the V3-V4 region of the 16S ribosomal RNA gene on the MiSeq Illumina platform. We collected 59 wild (9 with T. cruzi infection) and 10 lab-reared T. infestans (4 with T. cruzi infection) from the endemic area of Arequipa, Perú. Wild T. infestans had greater hindgut bacterial diversity than laboratory-reared bugs. Microbiota of lab insects comprised a subset of those identified in their wild counterparts, with 96 of the total 124 genera also observed in laboratory-reared insects. Among wild insects, variation in bacterial composition was observed, but time and location of collection and development stage did not explain this variation. T. cruzi infection in lab insects did not affect α- or β-diversity; however, we did find that the β-diversity of wild insects differed if they were infected with T. cruzi and identified 10 specific taxa that had significantly different relative abundances in infected vs. uninfected wild T. infestans (Bosea, Mesorhizobium, Dietzia, and Cupriavidus were underrepresented in infected bugs; Sporosarcina, an unclassified genus of Porphyromonadaceae, Nestenrenkonia, Alkalibacterium, Peptoniphilus, Marinilactibacillus were overrepresented in infected bugs). Our findings suggest that T. cruzi infection is associated with the microbiota of T. infestans and that inferring the microbiota of wild T. infestans may not be possible through sampling of T. infestans reared in the insectary.

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

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

Live animals are the preferred food source for rearing and keeping triatomines in insectaries. However, there is an increasing demand for artificial feeding as an alternative method to using live animals. Despite this demand, scientific studies showing the viability of rearing triatomine colonies in insectaries with artificial feeding are still lacking. In this regard, we tested whether feeding triatomines with an artificial system affects different physiological and biological parameters during the insects' development. Three experimental groups were established for the species Triatoma infestans and Panstrongylus megistus. The insects were fed weekly and individually, with each group receiving different treatments, as follows: A) artificial feeding system with rabbit blood, B) live animal host, and C) alternating feeding (one week A and the next B). The groups were kept under the same environmental conditions and monitored daily. The parameters evaluated per instar and total cycle were the effect of the blood supply method on the insects' developmental time, the association between feeding method and insect mortality, weight gain, and the number of feedings needed to trigger molting. The latter two were evaluated only in P. megistus. Sex did not influence the insects' survival or weight gain. The biological cycle duration was shortest in insects fed on a live animal host, followed by the group fed alternately, and longest in those fed artificially. Panstrongylus megistus fed on an artificial system required more feedings to complete molting and gained less weight. The insect mortality rate was not influenced by the feeding method. This is the first study showing that artificial feeding conditions affect different physiological parameters in two triatomine species, questioning the viability of exclusive artificial feeding as a sustainable strategy in a laboratory environment.

Triatoma sanguisuga (Leconte) is one of the most widely distributed kissing bugs in the United States, associated with an extensive zoonotic circulation of Trypanosoma cruzi, the agent of Chagas disease, in a large part of the country. However, the actual risk for human infection in the United States is poorly understood. Here, we further assessed the ecology of T. sanguisuga bugs collected in residents' houses in Illinois and Louisiana, using a metagenomic approach to identify their blood-feeding sources, T. cruzi parasites and gut microbiota. Blood meal analysis revealed feeding on domestic animals (dogs, cats, pigs, goats, and turkeys), synanthropic species (raccoons, opossums, and squirrels), as well as the more sylvatic white-tail deer. Human blood was identified in 11/14 (78%) of bugs, highlighting a frequent vector–human contact. The infection rate with T. cruzi was 53% (8/15), and most infected bugs (6/8) had fed on humans. A total of 41 bacterial families were identified, with significant differences in microbiota alpha and beta diversity between bugs from Louisiana and Illinois. However, predicted metabolic functions remained highly conserved, suggesting important constraints to fulfill their role in bug biology. These results confirmed a significant risk for vector-borne transmission of T. cruzi to humans in Louisiana and Illinois, which warrants more active screening for human infections. Also, while there is broad plasticity in the bacterial composition of T. sanguisuga microbiota, there are strong constraints to preserve metabolic profile and function, making it a good target for novel vector control strategies. Graphical Abstract

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.

Triatomine bugs (Hemiptera, Reduviidae, Triatominae) are blood-sucking vectors of the protozoan parasite, Trypanosoma cruzi, which causes Chagas disease, a significant source of human morbidity and mortality in the Americas. Autochthonous transmission of Chagas disease in the United States is considered rare, despite evidence of Triatoma species harboring T. cruzi, invading homes, and biting occupants. In the southeastern United States, Triatoma sanguisuga is considered common, yet its distribution, host use, and T. cruzi infection are practically unknown in this region. Using field sampling and community science programs from 2013 to 2023, we collected triatomines from peridomestic and domestic settings, identified them to species, analyzed for bloodmeals, and screened for T. cruzi infection and Discrete Typing Units (DTUs) TcI - TcVI utilizing molecular techniques. Triatoma sanguisuga (n = 310) were collected from 23 counties throughout the state, particularly in northern and central Florida. More than one third (34.6%) of T. sanguisuga were found inside a human dwelling, and 39.2% were collected by community members. T. cruzi infection was observed in 29.5% (88/298) of tested triatomines, with infection found in 12 of the 23 counties where triatomines had been collected. DTU-typing was successful for 47 of the T. cruzi-positive triatomines: 74.5% were infected with DTU TcI, 21.3% were infected with DTU TcIV, and 4.3% were co-infected with TcI and TcIV. Bloodmeal analysis of 144 T. sanguisuga found broad host use, including mammals (60%), ectothermic vertebrates (37%), and cockroaches (2.5%). Human blood meals contributed nearly a quarter (23%) of bloodmeals, indicating significant vector-human contact. Our field data from Florida demonstrate that T. sanguisuga is present near, and sometimes in, human dwellings, feeds upon humans, and is infected with multiple DTUs of T. cruzi. This indicates that the environment in the southeastern United States is suitable for autochthonous transmission of Chagas disease or that the human risk for T. cruzi infection is possible. The roles of ectotherms in T. sanguisuga and T. cruzi ecology also warrant further investigation.

Trypanosoma cruzi, the causative agent of Chagas disease, is primarily transmitted through the infected feces of blood-sucking bugs known as triatomines. As a result, its transmission is closely linked to the feeding and defecation behaviors of these insects. T. cruzi can alter various physiological processes in its vectors, including those involved in parasite acquisition, development, and excretion. This study aimed to assess the feeding and defecation behaviors of Triatoma dimidiata sensu lato (Latreille,1811), one of the main vectors, in relation to its T. cruzi infection status. Using both T. cruzi-infected and uninfected T. dimidiata, we measured various variables related to feeding and defecation behaviors. Notably, infected insects reached their host four times faster and began defecating twice as quickly as uninfected ones (282 ± 58 s vs. 1132 ± 198 s; 580 ± 120 s vs. 1220 ± 166 s, respectively), and these differences were significant. Among the bugs that defecated, 89% (16/18) of infected insects and 70% (14/20) of uninfected insects defecated during feeding. Moreover, among the bugs that defecated, a significantly higher proportion of infected insects defecated within the first 10 minutes after the start of feeding (11/18 = 61%) compared to uninfected insects, in which this behavior was less frequent (5/20 = 25%) and occurred later. Additionally, infected insects presented a significantly greater blood meal intake and feeding rate. Overall, these findings suggest that T. cruzi alters the feeding and defecation behaviors of T. dimidiata in a way that could enhance its transmission potential.

Chagas disease is one of the most important vector-borne diseases in Mexico. Triatoma pallidipennis (Stål) is one of the most epidemiologically important vector species. Despite being classified as a single species, various studies (molecular, morphometric, and biological) on populations across its distribution suggested it is composed of a group of cryptic species. This study examined reproductive isolation among 5 populations of T. pallidipennis originating from the western, southern, and central regions of Mexico to help clarify the potential existence of a cryptic species complex of T. pallidipennis in Mexico. A generation of hybrids was analyzed for fertility and fecundity. Fertility rates varied from 50% to 100% in the parental crosses and from 20% to 100% in the F1 × F1 crosses. Fecundity ranged from 1.4 to 3.2 eggs/female/day in the parental crosses, which decreased to 0.9–2.9 in the F1 × F1 crosses (except in Jalisco × Morelos). The fertility of the eggs ranged from 61.4% to 85.4% in the parental crosses, dropping to 44% to 90.1% in some F1 × F1 crosses, indicating partial reproductive isolation among these populations.