Abstract
Function of the corpus allatum in the embryonic diapause in Bombyx was investigated by experimental morphological methods. It is a well-known fact that the corpus allatum does not secrete the diapause hormone by itself in Bombyx. However allatectomy resulted in the change of diapause eggs into non-diapause ones, and the most effective period for allatectmy corresponded to 72hr after the 4th ecdysis in tetramolters.
Effect of the corpus allatum on the hormonal activity of the suboesophageal ganglion was examined. Allatectomy performed in 72hr old 5th instar larvae decreased the activity of the suboesophageal ganglion for the induction of diapause eggs. It was found that the secretion of diapause hormone by the suboesophageal ganglion of larvae producing non-diapause eggs became active by implantation of a pair of corpora allata from larvae producing diapause eggs. The secretion of diapause hormone by the suboesophageal ganglion of larvae producing non-diapause eggs was activated by mere contact for a certain period of time with corpora allata from larvae producing diapause eggs through the circulation of the active substances.
These results indicate that the corpus allatum controls the secretion of diapause hormone by the suboesophageal ganglion.
