The harmful effect of light on Drosophila is diet-dependent

Larvae and pupae of Drosophila melanogaster are light sensitive. Light increases mortality and retards development from egg to adulthood. This effect of light is diet dependent. High yeast concentrations protect larvae and pupae against the injurious effect of light. At low yeast concentrations the larvae and pupae become extremely light sensitive. Addition of vitamins to a low yeast medium also gave protection against light. A first analysis revealed that vitamin H (biotin) is involved in the protection. This is shown by the effect of avidin, an inhibitor of biotin dependent enzymes, on the development time. In all these aspects we recorded significant differences between two strains, a control strain C and a strain P. The latter had been adapted to a palmitic acid supplemented medium. In addition to the effect of vitamins on the survival, amino acids and sucrose supplements protect the control strain. These supplements have no effect on the survival of the P strain at high light intensities. At low light intensities they improve the survival of both strains. Palmitic acid supplements affect the survival of the control strain at both light intensities approximately to the same extent. The P strain is affected by palmitic acid only under the low light conditions.