Hormonal control of adult reproductive diapause in the Egyptian grasshopper, Anacridium aegyptium, L.

Abstract

SUMMARY The histology of the cerebral neurosecretory system and the corpora allata of Anacridium aegyptium is similar to that of other locusts, except that the adult diapause of this species introduces differences during oocyte growth. In diapausing adults of Anacridium, the cerebral neurosecretory cells contain large amounts of stainable material; when diapause is broken, the cells contain very much less material as the oocytes develop, but material accumulates once more when the oocytes are fully grown. The corpora allata are small in diapausing females, enlarge considerably during oocyte growth and vitellogenesis in post-diapause insects, and again decrease in size when the oocytes are fully grown. It is inferred from these observations that the neurosecrectory cells and the corpora allata are both inactive during diapause. But the effects upon oocyte growth of destruction of the neurosecretory cells, and of allatectomy, in diapausing females which are subsequently kept under conditions which terminate diapause in normal individuals, strongly suggest that the cerebral neurosecretory system is the primary cause of the inhibition of oocyte growth during adult diapause.