Antennal lobe organization and pheromone usage in bombycid moths

We investigated the neuroanatomy of the macroglomerular complex, which is dedicated for sex pheromone processing, in five species belonging to the subfamily Bombycinae, Ernolatia moorei, Trilocha varians, Rondotia menciana, Bombyx mandarina, and Bombyx mori. The glomerulus located at the dorsal-most part of the olfactory center shows the largest volume in most of the moth species studied thus far. Such normal glomerular organization has been observed in E. moorei and T. varians, which use a two-component mixture, including the compound bombykal as a mating signal. On the other hand, the other three species, which use another component as a single attractant, exhibit a modified arrangement of the macroglomerular complex. This correlation between pheromone usage and neural organization might be helpful for understanding speciation.