YEAST COMMUNITIES AS DESCRIPTORS OF HABITAT USE BY THE DROSOPHILA-FASCIOLA SUBGROUP (REPLETA GROUP) IN ATLANTIC RAIN-FORESTS

Yeast communities associated with four species of the Drosophila fasci ola subgroup (repleta group) in tropical rain forests were surveyed in an abandoned orchard, and rain forest sites of Rio de Janeiro and Ilh a Grande, State of Rio de Janeiro, Brazil. Adult flies of Drosophila c arolinae, Drosophila coroica, Drosophila fascioloides and Drosophila o nca frequently carried Candida colliculosa, Geotrichum sp, Kloeckera a zpiculata and a Pichia membranefaciens-like species. The most frequent yeasts in the crop of flies included Candida collicullosa, C. krusei, Pichia kluyveri and a P. membranefaciens-like species. The physiologi cal abilities and species composition of these yeast communities diffe red from those of other forest-inhabiting Drosophila. The narrow feedi ng niches of the fasciola subgroup suggested the use of only part of t he substrates available to the flies as food in the forest environment , as noted previously for cactophilic Drosophila serido (mulleri subgr oup of the repleta group) in a sand dune ecosystem. The cactophilic ye asts that were isolated have not been previously found in forests. The fasciola subgroup probably used epiphytic cactus substrates as breedi ng and feeding sites in the forest. The physiological profile of yeast s associated with the fasciola flies was broader than that of yeasts a ssociated with the cactophilic Drosophila serido, suggesting that the fasciola subgroup represents an older lineage from which the South Ame rican repleta species evolved.