RESUMEN Triatoma infestans y Triatoma platensis son especies interfértiles que en ocasiones comparten ecotopos y producen híbridos fértiles naturales. El cruzamiento interespecífico podría permitir la producción de genotipos híbridos capaces de colonizar nuevos hábitats. Por ello, los estudios de aspectos reproductivos sobre estos organismos son de gran importancia. En este sentido la oogénesis, proceso que implica el desarrollo del ovocito y permite la formación de huevos viables, es un aspecto relevante. En este estudio se caracterizaron aspectos histológicos enfocados en el desarrollo folicular de híbridos experimentales. Para ello, se extrajeron los ovarios de 35 hembras híbrido, se embebieron en parafina y colorearon con hematoxilina-eosina. Se caracterizó el desarrollo del epitelio folicular y del ovocito en las etapas de previtelogénesis y vitelogénesis, encontrándose que la oogénesis de las hembras híbrido se encuentra bien definida produciendo huevos viables y que los cambios ocurridos a nivel histológico se asemejan a los registrados en T. infestans.

ABSTRACT Triatoma infestans and Triatoma platensis are interfertile species that frequently share ecotopes and produce natural fertile hybrids. Interspecific crossing allows the production of more suitable hybrid genotypes capable of colonizing new habitats. Therefore, studies of reproductive aspects in hybrids are of great importance. In this sense, oogenesis, a process that involves the development of the oocyte and allows the formation of viable eggs, is a relevant aspect. In this study, histological aspects focused on the follicular development of experimental hybrids were characterized. To do this, the ovaries of35 hybrid females were removed, paraffin-embedded and stained with hematoxylin-eosin. The development of the follicular epithelium and the oocyte in the stages of previtellogenesis and vitellogenesis were characterized, finding that the oogenesis of the hybrid females is well defined producing viable eggs and that the changes occurred at the histological level resemble those registered in T. infestans.

Abstract To better understand the dispersion strategies of Triatoma infestans (Klug) (Hemiptera: Reduviidae, Triatominae), we evaluated the spatial effect of infested peridomicile and density vegetation cover in a historically endemic area for Chagas disease. The study was conducted in rural houses of the northwest of Córdoba province, Argentine, during 2012-2013. Active search of triatomines were made in domicile and peridomicile habitats. To characterize vegetation coverage, a thematic map was obtained considering five types of vegetation cover (closed/open forest, closed/open shrubland and cultural land). From each house we extracted the area of vegetation coverage, housing density and infested peridomiciles density. We used generalized linear models to evaluate the effect of these variables on the occurrence of infested peridomicile. According to our results, the probability of a peridomicile to be infested increases by 1.34 (95%CI [0.98; 1.90]) times more when peridomicile structures are in environments with higher housing density and by 1.25 (95%CI [0.84; 1.88]) more times when houses are surrounded by open shrublands. Among the multiple ecological determinants of peridomestic infestation, the influence of vegetation cover has been poorly studied. In this study we discussed the effect of the vegetation as a potential modulator of the dispersion strategies of T. infestans.

Triatoma infestans is the main vector of Chagas disease in the southern cone of South America. This species is well adapted to living in rural houses and structures used for housing domestic animals (peridomestic habitats). In this study, we evaluated the relationship between the source of blood consumed by adults of T. infestans collected from different peridomestic habitats from two localities from Cruz del Eje department (Córdoba, Argentina) and their nutritional and reproductive status. In each individual, the ratio between body weight and total body length was used as an indicator of nutritional status (NS). The presence of sperm in spermathecae and the number of chorionated oocytes in ovaries and oviducts were considered indicators of reproductive status (RS) of females. The feeding source in the promesenteron of male and female insects was identifed using anti-chicken, anti-goat, anti-human and anti-dog antisera. Chicken coops were the main peridomestic structure present in the study area as well as the peridomestic sites with the highest percentage of T. infestans. Insects collected from the different peridomestic structures showed a NS between 8 and 15 mg/mm. Of the evaluated females, 35.7% presented chorionated oocytes. Food profle analyses revealed that chicken was the main blood source. Independently of the blood source, the triatomines presented a NS between 8 and 15 mg/mm. No specimens feeding exclusively on human blood were found; nevertheless, of 31.48% of insects feeding on mixed blood sources, 59% included human blood. All T. infestansspecimens that included human blood in the mixed blood source were collected from chicken coops and storerooms located in a 12-m area around domiciles. Human blood present in mixed blood meal of adult insects suggests that T. infestansmoves from domiciles to peridomicilies and vice versa.

Triatoma infestans es el principal vector de la enfermedad de Chagas en el Cono Sur de Sudamérica. Esta especie está bien adaptada a vivir en el domicilio y estructuras utilizadas para albergar animales domésticos (hábitats peridomésticos). En este trabajo evaluamos la relación entre la fuente de sangre consumida por los adultos de T. infestans recolectados de diferentes hábitats peridomésticos de dos localidades del departamento de Cruz del Eje (Córdoba, Argentina) y su estado nutricional y reproductivo. En cada individuo, la relación entre el peso y la longitud corporal total se utilizó como un indicador del estado nutricional (EN). La presencia de espermatozoides en espermatecas y el número de ovocitos corionados en ovarios y oviductos se consideraron indicadores del estado reproductivo (ER) de las hembras. La fuente de alimentación en el promesenterón de insectos machos y hembras se identifcó utilizando antisueros anti-gallina, anti-cabra, anti-humano y anti-perro. Los gallineros fueron las principales estructuras peridomésticas presentes en el área de estudio, así como los sitios con el mayor porcentaje de T. infestans. Los insectos recolectados en las diferentes estructuras peridomésticas mostraron un EN entre 8 y 15 mg / mm. De las hembras evaluadas, el 35,7% presentó ovocitos corionados. Los análisis del perfl alimentario revelaron que las gallinas fueron la principal fuente de sangre. Independiente de la fuente de sangre los triatominos presentaron EN entre 8 y 15 mg / mm. No se encontraron ejemplares alimentados exclusivamente con sangre humana; sin embargo, del 31,48% de los insectos que se alimentaron de fuentes de sangre mixtas, el 59% incluía sangre humana. Todas las muestras de T. infestans que incluían sangre humana en la fuente de sangre se recolectaron en gallineros y depósitos ubicados en un área de 12 m alrededor de los domicilios. La sangre humana presente en las fuentes de alimentación mixta sugiere que T. infestans se mueve de los domicilios a los peridomicilios y viceversa.

Abstract INTRODUCTION: The domestic and peridomestic presence of Triatoma infestans depends on several factors, such as human behavior, vector behavior, ecology, and the environment. METHODS: This work was conducted in 139 domiciliary units, where triatomines were captured and risk factors in domiciles and peridomicilies were recorded. Household dwellers were interviewed to obtain information about practices regarding this disease and entomological indicators were calculated. RESULTS: Infestation indices were 59.7% for house compounds, 4.3% for domestic areas and 58.3% for the peridomestic areas. Intradomicile infestation was significantly associated with housing characteristics. The presence of chicken coops in peridomicilies was associated with an increased risk of infestation. Of the respondents, 80% did not recognize the importance of the peridomiciliary structures for triatomine control and had infested peridomicilies. CONCLUSIONS: The results show the importance of peridomiciles as refuge sites for Triatominae bugs; however, household dwellers do not perceive peridomiciles as areas that favor the presence of vectors. Actions for raising awareness about factors that favor the presence of triatomines are needed to improve the conditions of peridomiciliary environments.