Organization of the retrocerebral gland system in lepidopterous larvae of the family pyralidae

The organization of the retrocerebral gland system in larvae of six species of Lepidoptera belonging to the family Pyralidae was compared using light and electron microscopy. We have demonstrated for the first time the presence of separate corpora cardiaca and corpora allata in the following economically important borers: the southwestern corn borer, Diatraea grandiosella, the sugar cane borer, Diatraea saccharalis, the European corn borer, Ostrinia nubilalis, and the rice stalk borer, Chilo plejadellus. In these species a long nervus corporis allati (ca. 300 μm) runs from the corpus cardiacum to the corpus allatum which is attached to the duct of the mandibular gland.The identity of the corpora allata of D. grandiosella was confirmed by transplantation. Corpora allata removed from pre-diapausing larvae and implanted into the haemocoele of early last stage non-diapausing larvae led to a high incidence of supernumerary larval rather than pupal ecdyses.