Fast phototaxis and electroretinograms in red-eyed and white-eyed retinal degeneration mutants of Drosophila melanogaster

Due to the presence or absence of screening pigments red-eyed and white-eyed Drosophila melanogaster have electroretinograms with different sensitivity spectra (Stark and Wassermann, 1974). The same differences were found in a comparison of ERGs of red-eyed and white-eyed retinal degeneration mutants. No effect of the pigments can, however, be found in the spectral sensitivity of escape phototaxis behaviour. The observations imply that only receptor cells in on-axis ommatidia contribute to this behaviour even in the white-eyed fly.