Abstract
Using chromatographic and spectrophotometric methods, riboflavin was determined to be the major component of yellow pigment in the Malpighian tubes of wild-type Drosophila melanogaster. While reduced yellow pigment accumulation in larvae of eye color mutants is consistently correlated with a reduction of drosopterin formation in adults, reduction of drosopterin synthesis is not always associated with decreased yellow pigment in Malpighian tubes.In the light mutant, reduced yellow pigment accumulation per se is not responsible for reduced drosopterin synthesis; however, a labile cytoplasmic factor associated with the light maternal effect does influence yellow pigment accumulation in Malpighian tubes.