LARVAL FORAGING BEHAVIOR IN ISOFEMALE LINES OF DROSOPHILA-MELANOGASTER AND DROSOPHILA-PSEUDOOBSCURA

Isofemale lines of Drosophila, recently sampled from nature, were used to study the within- and between-line phenotypic variability of a preadult behavior. The locomotory component of larval foraging behavior was quantified by measuring the length of the path transversed by a foraging 3rd instar larva on a yeasted dish. Significant between-line variation for this behavior was found in D. melanogaster and in D. pseudoobscura. Matings between lines with extreme phenotypes indicated a relatively simple genetic basis for differences in larval foraging behavior.