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Male and female T. infestans were released on two consecutive nights in the salinas of Cordoba Province, Argentina, when air temperatures during the flying period averaged 28.5 degrees C. 136 males (43% of the total released) and 170 females (57%) flew on the first night, and 6 males (18%) and 7 females (27%) on the second. Of these, we recovered 23 males and 14 females within 100 m, and a further female within 200 m, all from the first night's release. The remainder appear to have flown more than 100 m and possibly more than 200 m. In support of this conclusion 4 male and 5 female bugs were recovered in an abandoned brick house 550 m from the release point. Since the proportion of bugs apparently flying more than 200 m is considerably greater than that deduced from previous experiments at lower temperatures (Lehane & Schofield, 1981) it is possible that temperature influences not only the proportion of bugs flying but also the distance flown. Flight appears to be affected by wind speed. On the first night, when there was negligible wind, 43% of male and 57% of female bugs flew. On the second night, with winds gusting at 4-5 m/s, only 18% of the male and 27% of the female bugs flew.

By scanning electron microscopy, sensilla type and distribution were studied on the antennae of ten species of Rhodnius. No sexual dimorphism was apparent. Intraspecific differences in sensillar pattern were shown to be potentially useful in species determination and to agree with results from biochemical studies and previous morphometric studies in terms of species affinities. © 1994 Wiley-Liss, Inc.

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Abstract. Geometric morphometrics is a novel approach to biological shape analysis, and its application to medical entomology is just beginning. Here, we use it to examine geographical and interspecific variation in the Triatoma infestans complex, vectors of Chagas disease in southern Latin America. Using six landmarks defining the membranous part of the hemelytra, we analysed the geographical patterns of variation in several populations of T. infestans, including the recently described`dark morph' of T. infestans from hollow trees in the Bolivian Chaco. As a potential outgroup, T. melanosoma was added to the sample. A consistent geographical differentiation was observed, but no evidence was found in either sex to consider either the dark morph or T. melanosoma as a species distinct from T. infestans. Triatoma melanosoma is relegated to synonymy with T. infestans (syn.n.).

Background: Triatoma infestans is the main vector of Chagas disease in the Gran Chaco region of South America. The traditional spraying technique used for the application of pyrethroid insecticides has shown low efficiency in the elimination of the vector species populations occupying peridomestic structures of rural houses in the endemic area of Argentina. As part of studies looking for better alternatives, we evaluated the residual effect of insecticidal paints on the mortality of fourth instar nymphs of T. infestans.

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