Natural ecotopes of Triatoma infestans dark morph and other sylvatic triatomines in the Bolivian Chaco

A survey of natural ecotopes of #Triatoma infestans$ dark morph and other triatomine sylvatic species was performed in an uninhabited area of the Bolivian Chaco. Among the 321 triatomines collected by light trapping, only 4 #T. infestans$ dark morph specimens were identified. Predominant flying species were #T. guasayana$ and #T. sordida$ group 2 (51.7% and 37.1% of capture, respectively). The same species prevailed in terrestrial and epiphytic bromeliads where scarce #T. infestans$ dark morph nymphal instars were also detected. In parrot nests #T. delpontei$ prevailed broadly over other species (90.2% of the capture) and only 4 #T. infestans$ dark morph adults were collected. In contrast, #T. infestans$ dark morph was the predominant species captured in hollow trees (46.0% of the total collected). The abundance of immature forms (88.2% of the collection) shows that hollow trees constitute a favourable ecotope for this species. Of the 421 trees investigated, 33.7% were positive for triatomines. #T. infestans$ dark morph, found inside 15.0% of them, also had higher apparent density than other species (average number of #T. infestans$ in positive trees, 2.0 plus or minus 1.6 vs 1.3 plus or minus 0.6 for other species). Light trapping seems to be an efficient method to sample the #T. sordida$-#T. guasayana$ complex in that it shows a similar distribution to that observed in natural ecotopes. However, this method is ineffective for the assessment of the local abundance of #T. infestans$ dark morph. (Résumé d'auteur