RELEVANCE OF THE ECOLOGY OF CITRUS YEASTS TO THE DIET OF DROSOPHILA

A study of the yeast flora of necrotic oranges and associated Drosophila yielded a total of 221 isolates composed of Kloeckera apiculata (75), Pichia fermentans (75), Pichia kluyveri (50), Torulopsis stellata (17), Hanseniaspora uvarum (2), P. membranaefaciens (1), and Candida vini (1). The yeast species of all samples of oranges and adult Drosophila were very similar; however, the species of Drosophila contained a higher proportion of P. fermentans and a lower proportion of K. apiculata than was found in the rotting oranges. P. fermentans was subsequently found more frequently on the surface of the necrotic tissue, where the flies feed, than was found internally. Since P. fermentans characteristically produces a pellicle and pseudomycelium and K. apiculata does not, it is concluded that the growth characteristics of the yeasts are an important factor determining adult Drosophila diets. © 1979 Springer-Verlag New York Inc.