Genotypic differences in larval olfactory discrimination in two Drosophila melanogaster strains.

Wild-type (+B) and compound chromosome mutant (bB) Drosophila melanogaster larvae were tested in a U-maze. Fresh Drosophila food or food and larvae were placed in each of the two goals (+B only in goal 1, bB in goal2) and served as stimulus. Separate trials were conducted using +B and bB larvae to test for preference in the maze. Significantly more test larvae went to the arm of the maze containing their own strain as stimulus when (1) both goals contained larvae, (2) one goal contained homogenetic larvae and the other fresh food only, and (3) the goals contained biotic residues of stimulus larvae. The strength of the stimulus necessary to elicit the response differed for the two strains, the +B strain apparently being more sensitive. As the density of the stimulus larvae was increased, the choices of the test larvae became statistically nonsignificant and the number of larvae remaining in the starting arm of the maze increased. The data suggested that the strains of larvae utilized here have the capacity for olfactory discrimination.