Activity of corpora allata, endocrine balance and reproduction in female Labidura riparia (Dermaptera).

The reproductive activity of Labidura riparia females involves, after a 5-day maturation stage, a regular alternation of ovarian cycles and egg-care stages averaging 10 days each. Vitellogenesis is characterized by an increase in the size of the corpora allata (CA) where structured SER bodies appear, and by a rise of juvenile hormone (JH III) content in the hemolymph which is followed by an increase in the level of ecdysteroids. During the egg-care periods, the CA are inactive; structured bodies generate autophagic vacuoles, the titer of JHs and later that of ecdysteroids in the hemolymph decreases and remains stationary. Ovariectomy causes hypertrophy and hyperactivity of the CA for about two months. Subsequently, the titer of JH decreases and old females may display parental behaviour; the level of ecdysteroids falls and remains unchanged. After cauterization of the pars intercerebralis (PI) of the protocerebrum, the ovarian activity stops, the ovary shrinks, the JHs rapidly disappear but ecdysteroids remain at the same or even higher levels than those of normal females of the same age. On the basis of these data, we postulate the existence of a center located in the PI, inhibiting the production of ecdysteroids, and of a stimulating center located outside this area. The PI also exhibits an allatotropic function.