Precocious termination of diapause in neck- and abdomen-ligated pupal preparations of the tobacco hornworm, Manduca sexta

When ligatures were placed between the head and thorax of freshly pupated hornworms, the resulting brainless preparations initiated adult development weeks earlier than intact diapausing controls and months earlier than similar preparations from which the brain had been surgically extirpated. This phenomenon could not be reproduced by removal of any single recognized cephalic neural or endocrine organ or any combination of organs. A similar accelerated development took place in many isolated pupal abdomens prepared by ligature or surgical section between the thorax and abdomen.Extirpation of the prothoracic glands of either diapause or non-diapause pupae resulted in only a very slight delay in the onset of adult development. Nevertheless, this development remained highly dependent on the brain, since preparations lacking brains as well as prothoracic glands underwent a prolonged developmental arrest. Preparations lacking prothoracic glands demonstrated elevated levels of ecdysone at the outset of adult de...