Feeding and oviposition preferences of Drosophila buzzatii for microbial species isolated from its natural environment

Abstract

Mature, mated female Drosophila buzzatii were given a choice of nine microbial communities actively growing on cactus homogenate in laboratory population cages. All communities contained identical naturally occurring bacteria, and comprised bacteria only and bacteria plus one of eight yeast species. Relative frequency of each yeast species ingested and number of eggs laid on each community were measured daily for three successive days. Flies generally preferred to feed and oviposit on those yeast species which are most abundant in rots of Opuntia cactus, and Pichia caclophila was the most preferred yeast. Light intensity, position of the yeast in the cage, and probably aggregation behaviour affected preference. Direct observation of adults was found to be inadequate for determining feeding preference. The ability of the flies to discriminate between yeasts developed with time. By day three, there was a significant correlation (r= 0.96) between the yeasts preferred for feeding and those preferred for oviposition. Feeding preference may be determined in part by oviposition preference; and the latter appears to be the most fruitful avenue for future research into habitat selection by D. buzzatii-