Drosophilid assemblages as a bioindicator system of human disturbance in the Brazilian Savanna

According to the Convention on Biological Diversity (CBD) the development of bioindicators is extremely necessary to achieve the conservation targets by 2010, and insects are considered an effective group for this goal. Drosophilids are regarded as potential indicators, although this idea remains untested. Therefore, we followed up a protocol to test the drosophilid potential indicator for human disturbance in the Brazilian Savanna, one of the richest and most threatened tropical biomes in the world. Sampling was undertaken in one urban environment and two biological reserves, representing four habitat types (undisturbed gallery forest, disturbed gallery forest, undisturbed savanna, and urban environment). We examined differences in the drosophilid assemblages among habitat types and used the Indicator Value (IndVal) method to point out the indicator species. We also tested the two-stage indicator validation, a protocol recently proposed in the literature, to validate the indicator species for undisturbed gallery forest and savannas, in independent samples. The assemblage variables varied mainly in undisturbed gallery forests, and reflected changes from an undisturbed to a disturbed stage. The IndVal associated with the two-stage protocol showed reliable characteristic species, which are very helpful for diagnostic surveys. Likewise, species that can detect changes in the habitats were also found. We found a set of indicators, which together may be very efficient for both assessing and reflecting a variety of conditions, improving the confidence of the bioindication system, expanding the taxonomic options for bioindicators, and therefore, contributing to the conservation of this region.