A POSSIBLE ROLE OF POSTERIOR HALF OF LARVAL BODY ON THE PUPATION OF THE FLESHFLY, SARCOPHAGA PEREGRINA

Abstract

In mature larvae of the fleshfly ligatured tightly at the middle of the body, both anterior and posterior halves failed to pupate in dry condition, where intact larvae usually pupate in 17 hr. When the ligatures were loosened after a certain period, the paralized larvae began to pupate in 16-18 hr.
Single injection of ecdysterone of 10μg per g body weight induced full pupariation of the isolated anterior and posterior parts, showing that the blocked pupation in both parts of ligatured larvae is due to prevention of synthesis and secretion of ecdysone in the ring gland. Severance of the peripheral nerves just behind the ganglionic mass or of the recurrent nerves just in front of the proventricle did not show any influence upon the pupation time. Artificial shrinking of the crops did not accerelate pupation in wet condition, nor continuous supply of oxygen reduced the duration till pupation of the anterior parts.
When ligations were applied at the level behind the 10th segment larger anterior parts pupated mostly within 40 hr.
These results suggest that some humoral factor derived from a certain region in posterior segments, probably located in 11th to the last segments, may play an important role in synthesis of ecdysone at the ring gland.