Peridomestic distribution of Triatoma garciabesi and Triatoma guasayana in north‐west Argentina

Abstract

The Reduviid bugs Triatoma garciabesi Carcavallo et al. (Hemiptera: Reduviidae: Triatominae), previously known as T. sordida Ståhl in the semi-arid chaco region, and T. guasayana Wygodzinsky & Abalos, vectors of Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae), were found to occupy wide but different ranges of ecotopes in the peridomestic environment. At Amamá and nearby rural villages in north-western Argentina, a combined total of 1233 specimens were collected from 325/2314 (14%) sites surveyed at 6-monthly intervals from November 1994 to November 1996. Triatoma garciabesi and T. guasayana displayed a significantly different distribution among peridomestic ecotopes. Triatoma garciabesi predominated over T. guasayana in the prevalence of infested sites, the number of colonies and the number of bugs collected. For T. garciabesi, the predominant ecotopes most likely to yield T. garciabesi repeatedly were the rugged bark of Prosopis alba or P. nigra (Fabaceae) trees, where chickens roosted, and chicken coops. For T. guasayana the main ecotopes were goat or sheep corrals, piled materials and orchard fences. Triatoma garciabesi and T. guasayana were collected concurrently from the same site on 9/2314 (0.4%) occasions, and on different dates at the same site on 12 (0.5%) occasions. The observed low frequency of mixed populations (< 1%) was not significantly different from that expected from a hypothesis of independence. Triatoma garciabesi clearly outnumbered T. guasayana in four of the nine mixed populations, none of which persisted as such. Neither T. garciabesi nor T. guasayana colonized human habitations, even in the absence of T. infestans (formerly the predominant domestic vector of T. cruzi in this area), a situation that apparently has not changed in the last 50 years in northern Argentina.

An overview on the ecology of Triatominae (Hemiptera:Reduviidae)

“…Shelter of a sloth (Lent and Wygodzinsky, 1979) # # Yes (Lent and Wygodzinsky, 1979) T. eratyrusiformi s Among rocks and in stone walls (Lent and Wygodzinsky, 1979) # (Lent and Wygodzinsky, 1979) # (Lent and Wygodzinsky, 1979) T. garciabesi Under tree barks (Canale et al, 2008) Observed in a wide range of peridomestic structures (Canale et al, 2008) # #…”

Genetics and evolution of triatomines: from phylogeny to vector control

“…Such ecological displacement has indeed been observed in laboratory experiments where T. infestans consistently excluded T. sordida after a few months (Bar et al, 1994;Oscherov et al, 2001Oscherov et al, , 2004. Indirect field evidence of competition includes observations of higher house infestation and abundance of T. sordida (Canale et al, 2000;Oscherov et al, 2004), P. megistus (Villela et al, 2005) and T. brasiliensis (Pereira et al, 2006) after removal of T. infestans by control programs. Intraspecific and interspecific competition for blood meals appears to be the key mechanisms to explain such exclusion.…”

Distribution and pathogenicity of Trypanosoma cruzi isolated from peridomestic populations of Triatoma infestans and Triatoma guasayana from rural Western Argentina

“…The collection sites included corrals, pigpens, chicken coops, trees where chickens roosted, piled materials, orchard fences, storerooms, and kitchens. All bugs were examined in the field laboratory to determine numbers by species, stage and collection site as described by Canale et al (2000), stored and shipped to the laboratory for parasitological examination. Pools of feces from three live or moribund insects of a given species and collection site were examined for flagellate as described.…”

“…In Northern Argentina, T. sordida, T. guasayana, and T. garciabesi may have potential for domestication in the absence of T. infestans because they have sylvatic or peridomestic colonies and frequently invade human dwellings (Carcavallo & Martínez 1985. The main peridomestic ecotopes of T. guasayana are goat or sheep corrals (Canale et al 2000), but it is usually associated with bromeliads, Opuntia cacti and fallen logs (Wisnivesky-Colli et al 1997, Noireau et al 2000. The main peridomestic habitats of T. garciabesi are the rugged bark of Prosopis trees in which chickens roost and coops (Canale et al 2000).…”

“…The main peridomestic ecotopes of T. guasayana are goat or sheep corrals (Canale et al 2000), but it is usually associated with bromeliads, Opuntia cacti and fallen logs (Wisnivesky-Colli et al 1997, Noireau et al 2000. The main peridomestic habitats of T. garciabesi are the rugged bark of Prosopis trees in which chickens roost and coops (Canale et al 2000). The peridomestic environment includes key sites for the elimination of T. infestans, such as goat or pig corrals and chicken coops , and may be the interface between sylvatic and domestic transmission cycles of T. cruzi, where more parasite diversity can be found.…”