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.

Among the vectors of Chagas disease, Triatoma guasayana (Wygodzinsky & Abalos) is a peridomestic species with epidemiological importance in Argentina. It could play an important role in the transmission of Trypanosoma cruzi (Chagas) to man, in areas where Triatoma infestans (Klug) had been eliminated by insecticide spraying. The aim of this work was to evaluate two aspects of vectorial competence: feeding behaviour and defaecation patterns, and to compare them with publihed data on Triatoma sordida (Stal). These processes were studied in fifth instar nymphs fed ad libitum on a restrained pigeon. The results show blood meal size controlling excretion behaviour. The first defaecation was emitted at 4.8 ± 9.2 min, with 87.5% of the insects defaecating during the first 10 min post-feeding. The comparison with T. sordida shows that both species have a similar pattern of feeding and defaecation behaviour.

Entre los vectores de la Enfermedad de Chagas, Triatoma guasayana (Wygodzinsky y Abalos) es un vector peridomiciliario de importancia epidemiológica en la Argentina, debido a que se comportaría como un vector secundario de Trypanosoma cruzi (Chagas), especialmente en áreas donde las poblaciones de Triatoma infestans (Klug) han sido temporalmente erradicadas por tratamiento con insecticidas. En este trabajo se evaluaron aspectos de la competencia vectorial de ninfas V de T. guasayana relacionados con su patrón de alimentación y excreción, para compararlos luego con datos ya publicados de Triatoma sordida (Stal). Estos procesos fueron estudiados en insectos alimentados ad libitum sobre paloma. Los resultados obtenidos indican una estrecha relación entre tamaño de la ingesta y patrón de excreción. El tiempo medio de emisión de la primera deyección fue de 4,8 ± 9,2 min y el 87.5% de las ninfas defecó dentro de los primeros 10 min post-ingesta. La relación entre tamaño de la ingesta y tiempo de emisión de la primera deyección fue significativa (r= -0,32). La comparación con T. sordida muestra que ambas especies poseen patrones similares en cuanto a los hábitos de alimentación y excreción.

Among the vectors of Chagas disease, Triatoma patagonica is a species in the process of adaptation to the human environment being recently registered in urban and suburban zones. However, its importance as a vector of Chagas disease is unknown. The aim of this work was to evaluate two aspects of vectorial competence: the feeding behaviour and the defaecation pattern. These processes were studied in females of T. patagonica fed ad libitum on a restrained pigeon. The results showed that the blood meal size was negatively correlated with the time of first defaecation (r = -0.42). The first defaecation was emitted before the first 10 min and defaecations during feeding were frequent. A total of 73% of females, defaecated during the first 30 min post-feeding. These results suggest that if this species subsequently colonizes the domicile, it would be capable of transmitting Trypanosoma cruzi.