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This is a description of experimental field studies that evaluated the efficacy of Telenomus fariai as a biological control agent of Triatoma infestans, the main vector of Trypanosoma cruzi (the aetiological agent of Chagas disease) in the Southern Cone countries of Latin America. The objective of this note is to report the inefficacy of T. fariai to regulate the population abundance of T. infestans under field conditions in a narrative way, as the original data have long been lost and unpublished because "negative" results were not published at the time (1980s). The aim is to correct that selective reporting and inform interested colleagues about efforts made on an idea that was (and probably still is) very appealing at the time the work was made. [ABSTRACT FROM AUTHOR]

Triatoma infestans is the main vector of the parasite that causes the Chagas disease in South America. It is known that T. infestans has different reproductive and development patterns depending on whether they feed on birds or mammals. Using the head of adult insects as an estimator of the specimen development, we attempt to determine if there are any differences in the sexual size dimorphism associated with the availability of the food resource in T. infestans of natural habitats in the Llanos Riojanos region (Argentina). The nutritional status resulted higher in chicken coops and, in both habitats, it was higher for females in relation to males. The centroid size was larger in females than in males from chicken coops, but not in the specimens from goat corrals. Centroid sizes revealed smaller medians in goat insects in comparison to those coming from chicken coops. Sexual size dimorphism occurs associated with differences in the nutritional status only for triatomines from chicken coops in natural habitats. The heads shape was not influenced by the nutritional status. The sexual morphophysiological differences found in T. infestans help us understand aspects of the behavior of the species in diverse environments and its implications in the vectorial transmission of Trypanosoma cruzi. [ABSTRACT FROM AUTHOR]