Yeasts Isolated from Drosophila and From Their Suspected Feeding Places in Southern and Central California

Abstract

In 1948 Dobzhansky expressed the view that yeasts are important in understanding some of the forces of natural selection to which popula? tions of Drosophila flies are exposed. Since then there has been an intense interest in the relation of yeast to Drosophila in nature. Al? though certain aspects of this relationship have been studied, information pertaining to the taxonomy of yeast occurring in Drosophila flies is quite limited. Chatton (1913) reported the occurrence of Coccidiascus ligeri as an intestinal parasite of D. funebris. In 1944 Dobzhansky and Epling iso? lated a yeast, which they termed 5 farinosus (syn. Pichia farinosa), from the crops of D. pseudoobscura. Later, at Dobzhansky's suggestion, Wagner isolated some yeasts from the crops of D. pseudoobscura col? lected at Pinon Flats in the San Jacinto mountains in Southern Cali? fornia. These were identified by Mrak (unpublished data) as species of the genus Zygosaccharomyces. Wagner (1944) also isolated but did not identify 8 types of yeast from Opuntia fruits and demonstrated that the yeasts had different nutritional qualities for certain species of Dro? sophila. Buzzati-Traverso in 1950 3 isolated 15 cultures of Torulopsis from Drosophila flies trapped in the Po Valley in Italy. Hedrick and Burke (1950) and Hedrick and Burke (1952) identified 17 yeasts iso? lated from crop contents, feces, and immediate substrates of two species of flies (D. crucigera and D. pilimana) collected in Hawaii. Shehata and Mrak (1952) compared the intestinal yeast floras of successive populations of Drosophila. In this study emphasis was placed on the relation of the type of yeast to the population cycles of the differ? ent chromosomal types of Drosophila pseudoobscura rather than on the taxonomy of the yeast isolated. In somewhat similar work da Cunha et al. (1951) demonstrated that certain yeasts isolated from the crops