Julieta Nattero

Triatoma infestans and Triatoma platensis are closely related species that may coexist in peridomestic habitats and produce viable hybrids. Since dispersal is a key process in the epidemiology of Chagas disease, understanding how hybridization affects flight-related traits is important. Here, we compared head and wing morphology of parental species and experimental hybrids to assess whether hybridization alters traits associated with flight capacity and dispersal potential. Hybrids were obtained by crossing T. infestans females with T. platensis males. Head and wing shape were analyzed using landmark-based geometric morphometrics, whereas size variation, allometric relationships, and wing aspect ratio were evaluated using generalized linear and generalized least-squares models. Significant differences in head and wing morphology were detected among parental species and hybrids. Overall, hybrids exhibited intermediate phenotypes, combining morphological features of both parental species. However, several flight-related traits, including wing shape and aspect ratio, were more similar to those of T. infestans than to T. platensis. The positive association between wing shape and aspect ratio indicated that hybrids possess relatively elongated and pointed wings, suggesting a dispersal potential closer to that of T. infestans. Overall, hybridization generated a distinctive combination of morphological traits with potential implications for vector dispersal and Chagas disease transmission.

Objectives: Chagas disease has shifted from a predominantly rural infection to an increasingly urban health concern. In the Southern Cone, Triatoma infestans remains the main vector of Trypanosoma cruzi and is frequently detected in Argentine cities, with urban areas of San Juan representing the principal hotspot of active vector‐borne transmission. We evaluated post‐spraying house‐level T. infestans infestation persistence and compared detection by active manual searches (AS) with chemically baited adhesive sensors (CS). Methods: The study was conducted in the metropolitan area of San Juan, Argentina, where 432 houses were inspected at baseline. Houses with detected triatomines and adjacent houses were sprayed with beta‐cypermethrin. Follow‐up surveys were performed at 1, 3, 6, and 12 months. During the first three surveys, previously infested houses were randomly assigned to either AS or CS detection methods; at 12 months, all houses were reassessed using AS. Results: At baseline, 369 T. infestans (adults and nymphs) were detected in 20 houses. After spraying, infestation and abundance declined sharply and remained low over 12 months. Infested houses decreased from 20 to 5, and total abundance from 369 to 6 individuals. Most post‐spraying detections were sporadic and low‐density. Manual searches were the only method that consistently detected triatomine infestation. Although most highly infested houses showed marked reductions, one exhibited a later increase, and occasional shifts between outdoor and indoor infestation. Conclusions: These findings indicate that residual spraying can reduce T. infestans infestation in urban settings for at least 1 year, and that active manual searches show a strong operational performance for detecting low‐density residual infestations during urban surveillance compared to chemically baited sensors.

Background: Chagas disease has historically been linked to triatomines and rural areas. However, urban infestations by one of its vectors, Triatoma infestans , are increasingly being reported. Urbanization is reshaping vectorial transmission patterns of this disease, creating new collective health challenges. To provide evidence on the eco-epidemiological status of Chagas in the metropolitan region of San Juan, Argentina, this study integrates data collected on biomedical, epidemiological, socioenvironmental, and territorial factors. Methods: We conducted a cross-sectional analysis of 432 urban houses for infestations by Triatoma infestans and infection of these vectors with Trypanosoma cruzi , complemented by environmental, sociodemographic, and human practices surveys. Additionally, we carried out information, education, and communication (IEC) activities to engage with and become acquainted with the community. The IEC activities included immersive virtual reality experiences, community dialogue, and educational games in public spaces. Results: Our study revealed a house infestation prevalence with T. infestans of 10% both indoors and in the houses’ outdoor spaces; T. cruzi infection was not detectable in any of the insects . Wind was identified as an environmental factor associated with house infestation, as was the presence of chicken coops, in addition to the condition of the houses (structural condition, such as cracks and poor plastering, and how the outdoor space of the houses was used, e.g., for the storage of objects that had accumulated over time). A combination of sociodemographic and environmental factors influenced T. infestans infestation prevalence. The IEC activities reached over 150 community members and promoted a dialogue about Chagas disease and vector control. The virtual reality and educational games encouraged strong youth engagement, and the media campaign helped raise awareness and visibility of the issue in the region. Conclusions: The infestation prevalence of T. infestans in the urban area of San Juan highlights the need for urban-specific control strategies that differ from those used in rural settings. The key findings of this study, such as chicken coops being infestation hotspots and the importance of wind direction, and the unique urban context (high-density housing, a territorial institutional presence, and community networks), enable us to recognize opportunities for integrated, multi-actor control frameworks that actively involve communities. Graphical

The active dispersal of triatomines has great epidemiological importance as it constitutes the main mechanism of colonization and reinfestation. Walking dispersal and its locomotor system have been little studied in triatomines. The aim of this study was to characterize the locomotor activity of fifth‐instar nymphs of T. infestans and link it to morphometric characteristics of the body, legs and their articles. For locomotor activity, each insect was placed on a circular arena and was filmed while walking freely for 10 min. The variables analysed were distance travelled (TD), movement time (TM) and effective speed (ES). Photographs were then taken of the body, the right legs and their articles, and morphometric tools were used to obtain linear, size and shape metrics. On average, a nymph walked 470 cm and moved for 5 min at an ES of 98 cm/min. Positive correlations were observed for TD‐TM and TD‐ES. Body and leg lengths correlated mainly with ES. Linear measurements showed the same pattern for each leg: TD correlated with femur and tibia length, and coxa width; TM did not show correlation; and ES correlated with femur and meron length, and coxa width. Size variables showed different associations for each leg. Shape variables revealed the associations of the meron with TD for foreleg and of the femur with TD for mid and hind leg. The locomotor activity of fifth‐instar nymphs of T. infestans was highly variable in time and distance, with a relatively constant speed. The results suggest that linear dimensions are not linked to the function of each leg, but rather the size and shape of the articles. Thus, the specific function of the foreleg during walking would be linked to the size and shape of its proximal part, while that of the hind leg would be linked to the size and shape of its distal part. Our results provide a solid understanding of how the form of the locomotor structures is linked to walking performance.

Understanding the dispersal capacity of Triatoma infestans, the main vector of Chagas disease in South America, is vital for vector control and managing recolonization after insecticide use. This study compares the seasonal frequency of melanic and non-melanic T. infestans morphs in Northwestern Córdoba Province, Argentina, and examines their association with environmental variables, morphometric traits, nutritional status, and flight capacity. Insects were collected at the beginning and end of the warm season. Dorsal coloration, morphometric traits, nutritional status, flight-related indices, climatic variables, and vegetation cover were recorded. Chromatic morph frequencies were analyzed using chi-square tests. Biological predictors were identified through multi-model inference, and environmental associations explored with Canonical Correspondence Analysis. Melanic individuals decreased from early to late warm season, especially males. Wing loading correlated strongly with morphotype, being higher in non-melanic forms. Pronotum size were also a significant predictor. Nutritional status had no clear effect. Cattle pasture cover and rainfall influenced morph frequency, mainly in males. These results reveal a complex interaction between phenotypic and environmental factors shaping color morph variation, highlighting the importance of understanding these dynamics to optimize vector surveillance and control in areas prone to reinfestation.

Background: Chagas disease, transmitted by triatomine bugs, is a major vector-borne parasitic disease in Latin America. Triatoma infestans, the principal vector in the Southern Cone, is primarily controlled through residual insecticide spraying. However, resistance to pyrethroids, especially in Northern Argentina and Southern Bolivia, has emerged. Resistant T. infestans populations exhibit reduced fitness, including impacts on reproductive success and dispersal capacity. This study investigates the flight potential and morphological changes in T. infestans populations with varying levels of insecticide resistance, hypothesizing that resistance may induce morphological changes in wing and head structures related to dispersal. Methods: We analyzed three resistance profiles of T. infestans—susceptible (S), moderately resistant (MR), and highly resistant (HR)—collected from ten domestic or peridomestic sites in two municipalities from Chaco province, Argentina. We registered flight muscle development and measured flight-related traits (wings, heads, and the stiff and membranous portions of the wing) using a landmark-based methodology. We also assessed morphological disparity and covariation of these traits across toxicological groups. Results: Significant morphological differences were found between resistant and susceptible populations. The frequency of insects with and without muscle varied across toxicological groups only for females, exhibiting the highest proportion of HR insects with fight muscle (86.21%). MR and HR males exhibited smaller stiff portions of the wing and heads than S males. Shape variation analysis showed that S females had wider forewings than resistant females, while HR females had narrower wings with a wider stiff portion. Susceptible males had wider and longer wings compared with resistant groups. Additionally, resistant populations showed greater morphological disparity and reduced covariation between flight-related traits. Conclusions: Our study shows that pyrethroid resistance in T. infestans is linked to morphological changes in flight-related traits. These changes suggest a tradeoff between resistance and flight capacity, with energy allocated to resistance mechanisms potentially limiting flight. The reduced covariation between flight traits in resistant individuals supports the idea of pleiotropic effects. While resistant individuals may perform better in insecticide treated areas, their reduced flight capacity could limit long-distance dispersal, affecting population dynamics and vector control efforts. Graphical

The conformation of the Sordida subcomplex has been a topic of prolonged debate, with diverse methodological approaches employed to discern its constituent species. Up to now, Triatoma sordida , T. garciabesi and T. rosai comprise part of this subcomplex. Distinguishing and identifying these three species pose significant challenges due to their pronounced morphological similarity, overlapping distributions, and presence of natural hybrids. This study aims to uncover the genetic diversity and geographic spread of these three species by analyzing a mitochondrial cytochrome b gene fragment and complementing it with chromosomal studies across natural populations from an extensive geographical range, including Argentina, Bolivia, Brazil, and Paraguay. Phylogenetic analyses revealed genetic distances that suggest the presence of at least six putative species, rather than the three currently recognized. The present findings underscore the potency and significance of molecular analyses from natural populations for species identification and highlight the limitations of morphology in classifying Triatominae species.