YEAST COMMUNITIES OF THE CACTUS PILOSOCEREUS-ARRABIDAE AS RESOURCES FOR LARVAL AND ADULT STAGES OF DROSOPHILA-SERIDO

The feeding behavior of Drosophila serido on the yeast communities of necrotic stem tissue of Pilosocereus arrabidae were studied in a sand dune ecosystem of Rio de Janeiro, Brazil. The prevalence of cactophili c yeasts including Pichia barkeri, Candida sonorensis and Geotrichum s p. in the crops and external surfaces of D. serido reflected its assoc iation with the cactus habitat. The effective number of yeasts vectore d on the surface of flies was higher than that in the crops. Also over lap between the yeasts from stems and from crops was partial suggestin g selective feeding by the flies in the substrates visited. The female s had a higher effective number of yeast species and a lower similarit y than males with the yeast community of P. arrabidae. This was probab ly related to the search for oviposition sites by females. The presenc e of Pichia thermotolerans-like and Pichia amethionina var pachycerean a in the flies, but not in P. arrabidae stems, indicated that D. serid o was not limited to this cactus species. The larvae and adults lived in different patches with the adults feeding in patches with higher ye ast species richness. The larvae had a narrower feeding niche and high er overlap with Fl arrabidae, and preferred P. barkeri and Pichia cact ophila as food. Adult flies fed on patches with the most frequent yeas ts except for P. cactophila. Pichia caribaea was found in higher frequ ency in the adult crops than in the stems. Our data suggested that the re was food selection and diet partitioning between adult and larval s tages of D. serido.