Potential Colonization of the Peridomicile by Triatoma guasayana (Hemiptera: Reduviidae) in Santiago del Estero, Argentina

Abstract

Sylvatic triatomines might use the peridomicile as a 1st step in the process of domiciliation. Therefore, we evaluated the capability of sylvatic species to colonize the peridomicile of a rural area in the Province of Santiago del Estero, Argentina. The research was carried out in 6 houses in the village of Trinidad. The person per hour capture method was employed to determine the presence of triatomines in all the buildings (n = 44). Dispersing adults were collected by means of light traps and by villagers when approaching their houses. Triatoma infestans (Klug) was the most abundant species followed by the sylvatic Triatoma guasayana Wygodzinsky & Abalos. The branch pens, which included cacti, Opuntia quimilo, and bromeliads in their structure, were significantly associated with T. guasayana. Most of these insects had fed on domestic blood sources. With the exception of 1 Triatoma sordida (Stål), dispersing adults were T. guasayana; among those approaching houses, 12 were females (2 of which were infected with Trypanosoma cruzi Chagas) and 3 were males. T. guasayana was found to be capable of intensively invading the intradomicile and the peridomicile, showing a high tendency to settle in the ecotopes which included nontransformed raw material from the wild and where T. infestans was less abundant.

Vectorial capacity of Triatoma guasayana (Wygodzinsky & Abalos) (Hemiptera: Reduviidae) compared with two other species of epidemic importance

“…Since T. guasayana was found infected with T. cruzi in the wild, as well as invading housing, although without colonizing it, various authors support the hypothesis that this species would not only be acting as a link between the three cycles of parasite transmission (wild -peridomiciliary -domiciliary), but is also behaving as a possible secondary vector of the parasite in Argentina and is a potential substitute of T. infestans during the surveillance stage (Wisnivesky-Colli et al 1993, Gajate et al 1996, Cecere et al 1999.…”

“…With regard to the vectorial control of Chagas disease, the peridomicile vectors have a special importance due to their role in these processes and the re-infestation of housing during entomological surveillance. Among these vectors, T. guasayana and T. sordida, are species which might play a significant role in the transmission of T. cruzi to human beings, specially after the eradication of T. infestans from houses (Carcavallo et al 1985, Wisnivesky-Colli et al 1993, Gajate et al 1996, Cecere et al 1999, Noireau et al 1999, Canale 2000.…”

“…This last parameter, which was not considered in this study, should be studied in T. guasayana to see if it can be considered as a possible vector. In the wild, T. sordida and T. guasayana are species which occupy different peridomiciliary areas without coexisting, except in the "monte chaqueño" of Santiago del Estero, Argentina (Gajate et al 1996, Cecere et al 1999. Studies in Argentina on their dispersal capacity show that T. guasayana actively invades not only the peridomiciliary area but also the domestic area, where it is numerically superior to T. sordida.…”

“…Triatoma sordida and T. guasayana are closely related species of Triatominae since they are morphologically similar and occupy the same ecotopes with an overlapping distribution in northern Argentina and part of the Bolivian Chaco and Paraguay (Schofield 1994,Usinger et al 1966. Although originally they were wild species, they were frequently found in peridomestic and domestic habitats (Forattini 1980, Wisnivesky-Colli et al 1993, Gajate et al 1996, Noireau et al 1998 due to their domestic tendency, and may be considered as possible domestic vectors of Chagas disease.…”

“…Its epidemiological importance is considered but in 1985 its presence in housing, where T. infestans had been controlled by insecticides (Carcavallo et al, 1985), was mentioned. Studies in Argentina showed that both this species and T. sordida were secondary vectors of Trypanosoma cruzi (Chagas) and would be a potential danger for human beings during entomological surveillance, since T. guasayana, is not only able to invade homes and attack human beings and dogs but has been found naturally infected with the parasite (Carcavallo et al 1985, Wisnivesky-Colli et al 1993, Gajate et al 1996, Cecere 1999, Canale 2000.…”