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

Abstract

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 +/- 1.6 vs 1.3 +/- 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.

Sylvatic foci of the Chagas disease vector Triatoma infestans in Chile: description of a new focus and challenges for control programs

“…Because the baited system is likely to attract and capture starved bugs, the observed stage structure of both populations (Figs 3, 4) may be biased (Noireau et al 2000). We observed differing counts of T. infestans between seasons.…”

“…The Mantel/Haenszel Chi-squared test for stratified data also showed no differences when the positivity in each nymphal instar was compared between Putaendo and the previous data of the metropolitan region (Bacigalupo et al 2006) (X² H-M = 0.366; p = 0.55); however, results reported in other wild T. infestans foci in South America are highly variable. For e�ample, infection inde�es in endemic areas of Bolivia vary from 2.5% in the Chaco to 60% in the Andes (Noireau et al 2000, Cortez et al 2006. This wide range of infection was suggested to be the result of different sources of their blood meal hosts, with the lower levels resulting from feeding mainly on birds -which are not susceptible to T. cruzi -and the higher levels resulting from feeding mostly on mammals' blood (Noireau et al 2000, Cortez et al 2006.…”

Molecular epidemiology of domestic and sylvatic Trypanosoma cruzi infection in rural northwestern Argentina

“…Natural infection by T. cruzi has been found in several local species of sylvatic mammals (Carcavallo and Martínez, 1968;Ceballos et al, 2006;Diosque et al, 2003;Yeo et al, 2005), whereas the putative sylvatic vectors have only been identified in Bolivia (Noireau et al, 2000). In the Gran Chaco, the bug Triatoma infestans is the main or single domiciliary vector; dogs, humans and chickens are usually the main blood meal sources of domestic bugs, and dogs and cats are considered the most important domestic reservoir hosts of T. cruzi (Minter, 1976;Gürtler et al, 1997Gürtler et al, , 2007a.…”

Capture of Triatoma arthurneivai (Hemiptera: Reduviidae) using a new luminous trap in Southeast Brazil

“…The use of traps has been an alternative method for triatomine capture, contributing to knowledge of species distribution and their population dynamics 3 . Among the trap designs commonly used in field research are those that use illumination sources or live-baits as an insect attractant [4][5][6] .…”

“…During the period that the traps were in the field, one year, specimens from two another species were also captured: two females of Panstrongylus geniculatus (Latreille, 1811) and one female of Triatoma vitticeps (Stål, 1859), (18°11'54'' S 43°34'01'' W, 1,331m). Direct searches were also performed in the possible ecotopes surrounding the capture locations (stones, barks, nests and animals burrows), as well as the installation of 60 traps with mice as the attractive 5 , though no other specimens were found.…”