Cholinesterase and the Secretion of the Brain Hormone in Insects

Abstract

Growth and moulting in inseots are stimulated by a hormone from neuroseoretory oells in the brain. In diapause these oells fail to seorete their hormone, ? and van der Kloot (1955) oorrelated this failure with the disappearanoe of oholinesterase and oholinergio substanoe from the brain. The experiments reported here show that eserine, whioh blooks the aotion of oholinesterase, will also retard the adult development of Phalaenoides glycine Lew. (Lepidoptera) if injeoted into the pupa before the brain has released its hormone. But in Pieris rapae L. and Danaus plwippu8 L. (Lepidoptera) the brain has usually seoreted suffioient hormone before pupation and eserine does not delay adult development when it is injeoted into these pupae. Apparently oholinesterase is essential to the secretion of the brain hormone in non-diapausing insects, and by blocking it an artificial diapause may be induced.