The role of neurosecretory neurons in the pars intercerebralis and pars lateralis in reproductive diapause of the blowfly, Protophormia terraenovae.

Microlesions of the brain were made to examine the role of neurosecretory neurons in the pars intercerebralis (PI) and pars lateralis (PL) in the induction of reproductive diapause of the female blowfly Protophormia terraenovae. Under both diapause-inducing (LD 12:12, 20 degrees C) and diapause-averting conditions (LD 18:6, 25 degrees C), the ovaries invariably failed to develop when the PI was removed. When the PL was removed bilaterally, the ovaries developed in most of the females, irrespective of the rearing conditions. Removal of the PL prevented females from entering reproductive diapause. These results show that certain neurosecretory neurons in the PI are necessary for vitellogenesis, and that the PL contains inhibitory neurons which suppress vitellogenesis during reproductive diapause.