Hormone-pheromone relationships in the beetle, Tenebrio molitor

A study was undertaken to determine the rôle, if any, of the neuroendocrine system in the production of a sex pheromone by adult females of Tenebrio molitor. The corpora allata, brain, the entire head, the frontal ganglion, or the ovaries were removed from newly emerged females. Ten to 14 days after the operation the pheromone content of these females was estimated in comparison with that of appropriate controls by biological assay. The pheromone activity of the extracts from females subjected to allatectomy and/or brain removal, or to decapitation, was significantly decreased when compared with sham-operated controls or normals. Reimplantation of the corpora allata or brain did not restore the pheromone level. However, treatment with juvenile hormone analogues was able to counter the effect of the operations. Removal of the frontal ganglion or the ovaries did not have any significant effect. The experimental results indicate that the secretion of the corpus allatum (juvenile hormone) is directly involved in the control of pheromone secretion; an intact brain-corpus allatum axis appears to be essential for normal production of pheromone by female T. molitor.