Efeito das clareiras de ação petrolífera sobre a composição de Drosophilidae (Diptera) na Bacia do Rio Urucu, Coari-Amazonas

Abstract

Drosophilidae are ecosystem condition indicators in relation to the effects of deforestation in tropical rainforest, and are a tool for designing conservation strategies in large biomes. A study in the Urucu oilfields (State of Amazonas, Brazil), was conducted seeking to compare richness and diversity of drosophilidae in artificial clearings (oilfields), natural clearings and continuous forest. Three excursions took place between 2003 and 2005. Fermented banana traps were used in 33 sites: 11 natural clearings, 16 artificial clearings and six continuous forest transects. We also, tested in the field the ability of nine species to develop is these three habitats. We captured 7,652 insects, 4,354 of which belonging to the Order Diptera (56,90%), distributed among 24 species of Drosophilidae, of two subgenus, Sophophora and Drosophila. Species distribution varied among habitats. 60,54% of the drosophilidae were of the willistoni subgroup, heavily concentrated in primary forest (79,09%). The second largest subgroup was ananassae (10,40% of total drosophilidae), in higher concentrations in oilfields (35,36%). The species accumulation curves, with 227 samples did not approached asymptotes; the estimates varied between 24 and 34 species. Jaccard coefficient similarity analysis shows 55% likeness between natural clearing and oilfield habitats, while in Morisita it measured 98,1% between primary forest and natural clearings. D. malerkotliana was the only specie of the ananassae subgroup that appeared in all habitats, with significant variations (ANOVA, p=0.001). Willistoni subgroup species appeared less frequently, only in forest areas, regardless of the original location of parental xv flies. These results show the effectiveness of the methods used and the need to increase the sampling effort to estimate the actual diversity of fruit Drosophilidae.