Meeting Abstract

31.2  Wednesday, Jan. 5  Respiratory physiology and the initiation of molting in the tobacco hornworm, Manduca sexta CALLIER, V.*; NIJHOUT, H. F.; Duke University; Duke University vc12@duke.edu

In Manduca sexta, the molting process is initiated when larvae attain a set size, the critical weight. Although the critical weight phenomenon is well documented, the physiological event that initiates the molting process is not known. We hypothesize that, during the intermolt period, the tracheal system is fixed in size, which puts an upper limit on the rate of oxygen supply. Metabolic demand for oxygen increases with body size, so oxygen supply could become inadequate beyond a certain size. Lack of oxygen might therefore trigger the molt, during which the old tracheal system is shed and replaced with a new larger one.