Modulation of reproductive output in Drosophila by spectral properties of ambient light

Abstract

The net reproductive output was determined for two strains of Drosophila melanogaster, wild-type (+) and white-eyed (w), under conditions of varied wavelength and intensity of illumination. The reproductive output of wild-type flies raised under blue light (max. 470 nm) was significantly lower (p < 0.01) than that of organisms grown under red (max. 630 and 660 nm) or green(max. 530 nm) illumination, or under conditions of total darkness. In contrast, blue light did not depress the reproductive output of white-eyed flies. The differential reproductive response of the two strains, then, appears to be related to genetically determined properties of the eye. Changes in the radiant fluence rate over a 10-fold range were not found to significantly modify reproductive output of wild-type flies, and if flies were illuminated with red, green, or blue light at identical fluence rates, those under blue, again, had a significantly lower (p < 0.01) reproductive output than the other two. The data suggest that the emission spectrum, not the radiant light intensity, significantly affects the number of offspring produced per parent.