Larval behavior of Drosophila central complex mutants: interactions between no bridge, foraging, and Chaser.

The central complex (CC) is a prominent component of the adult insect brain. In Drosophila melanogaster, mutations which alter CC structure also impair adult locomotion. This has led to the suggestion that the CC functions as a higher organizer of adult locomotor patterns (Strauss and Heisenberg, 1993). In the present study, we describe altered larval behavior resulting from mutations in six CC structural genes. Differences from the control strain were found for larvae from each CC mutant strain in at least one of three assays. central body defect1 (cbd1), central complex deranged1 (ccd1), central brain deranged1 (ceb1) and central complex1 (cex1) larvae all had general defects in locomotion (on a non-nutritive agar surface). Both ellipsoid body open2 (ebo2) and no bridge1 (nob1) had larval foraging behavior defects (on a nutritive yeast surface). Only cex1 larvae required significantly longer time in a roll over assay of muscle tone. Genetic analysis suggested that nob1 interacts additively with two other genes influencing larval foraging behavior, foraging (for) and Chaser (Csr). for also had an influence on adult foraging, whereas here we found that Csr did not. We did not include adult foraging behavior tests of the CC mutants due to general locomotion defects in these flies (Strauss and Heisenberg, 1993).