YEASTS VECTORED BY DROSOPHILA-QUADRUM (CALLOPTERA GROUP) IN TROPICAL RAIN-FORESTS

Yeast-Drosophila interactions in Tropical Rain Forests of Brazil are s pecialized when compared to temperate ecosystems, and tropical species of Drosophila have preferences that vary in the degree of choice of y easts. Yeasts associated with Drosophila of the forest-inhabiting trip unctata, willistoni and guarani groups are probably of fruit origin. T hey differ from yeasts isolated fi om the fasciola subgroup flies of t he repleta group, which seem to colonize epiphytic cacti in the forest canopy. The yeasts vectored by Drosophila quadrum (calloptera group) were surveyed and compared with the communities associated with the fl ies of tripunctata, willistoni, guarani and the cosmopolitan melanogas ter group in forest sites of Rio de Janeiro. The yeasts vectored by D. quadrum included Candida guilliermondii, Debaryomyces melissophilus, Debaryomyces vanriji, Kloeckera apis, Pichia membranaefaciens and Rhod otorula rubra as most frequent species. These yeasts are usually assoc iated with flowers and deteriorating fruits in the forest, indicating that D. quadrum feeds preferably on flowers and fruits in advanced sta tes of decomposition. The yeasts associated with the calloptera group were similar to yeasts isolated from the tripunctata and guarani flies that probably occupy similar niches on the forest floor and vicinitie s. The calloptera flies had a lower niche overlap with flies from the fasciola subgroup, and from the willistoni and melanogaster groups in the sane forest.