A homeotic mutation influences the wing vibration patterns during mating in males of the silkworm moth Bombyx mori.

An abnormality in the wing vibration pattern in males of the E(Nc) homeotic mutant of Bombyx mori was investigated. The wild-type (+/+) males show a switching of the rhythmic wing vibrations from a sequential pattern to an intermittent pattern during mating, whereas the E(Nc) mutants show a sequential pattern both before and during mating. Wing motions in +/+ males became small during mating, but those in +/E(Nc) males did not. Ablation of the head ganglia of +/+ and +/E(Nc) males during mating caused no change in the motor patterns of wing vibrations. Ablation or cooling of the posterior abdomen in the +/+ males during mating caused sequential wing vibrations, suggesting that the change in wing vibrations is induced by signals from the posterior abdomen. The pterothoracic ganglion in the +/E(Nc) males is separated into two ganglia, in contrast to the complete ganglionic fusion in the +/+ males. The neurons in the pterothoracic ganglion stained from abdominal nerve cords are homologus in +/+ and +/E(Nc) males, but many of these in +/E(Nc) males are elongated along the anteroposterior axis. These results suggest that the wing vibration pattern is restricted by genetic factors through reconstruction of the thoracic nervous system during metamorphosis.