Diagnóstico da diversidade de Phlebotominae (Diptera: Psychodidae) em uma paisagem fragmentada no Amazonas, Brasil.

Abstract

To diagnose the diversity of Phlebotominae in a fragmented landscape in Amazonia, the species richness, abundance and composition of sand flies in light trap samples from three Fazendas (cattle ranches) north of the city of Manaus were compared. Sampling was done in continuous primary forest, forest fragments of one, ten and one hundred hectares, and secondary vegetation (the matrix of the fragments), at one meter and fifteen meters above the florest floor, in the interior and at the edges of the different treatments. A pilot trial of light traps suplemented with a source of carbon dioxide was carried out to evaluate the cost effectiveness of this attractant. Female sand flies collected from their day time resting places on tree trunks were dissected for parasitological examination. The Phlebotomine fauna of the three fazendas in the area of the Biological Dynamics of Forest Fragments Project was found to include 58 species of Lutzomyia and one species of Brumptomyia among the 23 303 specimens collected. Light traps supplemented with carbon dioxide captured more sand flies than did the control traps, but the increased productivity was considered insufficient to compensate the additional cost and possible selective bias in the relative abundance of individual species. Samples from 15 m above the forest floor had on average fewer species and individuals than those taken at 1 m, with significant differences in the relative abundance of some species. Between fazendas, species richness and abundance varied more as a function of season (lower in the dry period) than of space over a range of 40 km. The three fazendas could be discriminated both in terms of presence or absence of species and their relative abundance. Comparisons of contemporaneous samples from different environments within fazendas revealed divergent patterns between fazendas. Vector species infected with Leishmania were found in fragments as small as 1 ha, which is consistent with the habits of at least Didelphis marsupialis, a mammalian reservoir host of Leishmania guyanensis.