Spectral sensitivity of wildtype and mutant Drosophila melanogaster larvae

Wild-type (Canton-S) Drosophila melanogaster larvae are generally repelled by white light. Mutant larval photokinesis A (lphA) larvae are less strongl y repelled than controls. Mutant Larval photokinesis B (LphB) larvae are un responsive to light, as are larvae from LI2, an isofemale line whose progen itors were recently derived from a natural population. To characterize the behavior of larvae from the mutant stocks and the isofemale line more preci sely, we determined the range of wavelengths that repel wild-type (Canton-S ) D. melanogaster larvae and identified wavelengths to which larvae are mos t sensitive. In comparison to adult flies, Canton-S larvae are much less se nsitive to white light and respond to a narrower range of wavelengths. The wavelengths to which Canton-S larvae are maximally sensitive are 500 nm (gr een), 420 nm (indigo), and 380 nm (ultraviolet). Mutant lphA larvae respond abnormally to green and indigo light but are as strongly repelled by ultra violet light as controls. In contrast, mutant LphB larvae and larvae from t he LI2 isofemale line are unresponsive to green, indigo, or ultraviolet lig ht. Thus, lphA larvae have a wavelength-specific defect, while LphB and LI2 larvae are generally unresponsive to wavelengths that repel wild-type larv ae.