Characterization of Triatoma guasayana Biotopes in a Hardwood Forest of Santiago del Estero, Argentina
Vol.96(4): 459-466, May 2001
Darío Vezzani,Nicolás J Schweigmann,Silvia M Pietrokovsky, Cristina Wisnivesky-Colli+
Unidad de Ecología de Reservorios y Vectores de Parásitos, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, 4º p, 1428 Buenos Aires, Argentina
Triatoma guasayana is a silvatic triatomine species distributed in Argentina, Bolivia and Paraguay. The study was performed in a secondary forest of Santiago del Estero, Argentina. The abundance of T. guasayana was evaluated by census in the following wild biotopes: quimiles (Opuntia quimilo), chaguares (dry bromeliads), logs and underground burrows. Ten biotopes of each type were dismantled in winter (August) and another 40 in summer (January); all fauna was recorded. The biotopes most infested by T. guasayana were quimiles (65%), followed by chaguares (55%), and logs (25%). Quimiles and chaguares were infested in both seasons, whereas logs were positive only in summer and burrows were never infested. Infestation and abundance were higher in summer than in winter. The biotope structure is a key factor for T. guasayana colonization. The larger number of refuges, the constant presence of blood sources and suitable inner microclimatic conditions offered by quimiles may favour the persistence of T. guasayana colonies. The richness of invertebrate fauna per type of biotope was ranked in the same order as that of T. guasayana, suggesting similar microhabitat requirements for all studied arthropods.
Key words: Triatoma guasayana - silvatic triatomines - microhabitats - biotopes - census - Argentina
Triatoma guasayana Wygodzinsky & Abalos is a silvatic triatomine species (Hemiptera: Reduviidae) distributed in Central and Northern Argentina, Bolivia, and Paraguay (Lent & Wygodzinsky 1979, Noireau et al. 1999). In the hardwood forest of Santiago del Estero, Argentina, T. guasayana has been found in dry cactacea, bromeliads, and logs, which are also used as temporary shelters by opossums (Didelphis albiventris), the main wild reservoir host of Trypanosoma cruzi (Schweigmann et al. 1999).
Those biotopes, considered as wild parasite transmission foci, showed very low T. guasayana densities (Wisnivesky-Colli et al. 1997), probably due to the methods used to capture triatomines. Conventional sampling methods (man/hour method, inspection using dislodging substances) do not ensure an accurate estimation of the population inhabiting a biotope. The census, an extremely demanding method, was unnecessary in previous studies on biotope occurrence and spatial distribution of T. guasayana. However, the fact that silvatic transmission modeling needs more precise values of T. guasayana abundance, prompted us to carry on a census in every biotope.
Since Schweigmann (1994) showed that opossums periodically shelter in underground burrows (caves), we included in our study these biotopes which had never been inspected for triatomines before.
Although available literature provides general information on triatomine habitat (Rabinovich 1985), there are no specific descriptions of inner biotope structures with the exception of palms in Venezuela (Pifano 1973, Rossell Reyes 1984). In order to characterize the microhabitat of T. guasayana, we describe the inner structure of its biotopes and the coexisting fauna.
ACKNOWLEDGEMENTS
To Lic Patricia Gajate for the taxonomic determination of triatomines and to Mr Ibera and Mrs Leo Sosa for their hospitality and help during the fieldwork.
Fig.1 | Fig.2 | Fig.3 | Fig.4 | Fig.5 | Fig.6 | Table I | Table II
This research was supported by the Secretaría de Ciencia y Técnica, Universidad de Buenos Aires (PID EX 184).
+Corresponding author.Fax: +54-11-48545412.E-mail:criswi@biolo.bg.fcen.uba.ar or tato@ba.net
Received 29 May 2000
Accepted 14 February 2001
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