THE ROLE OF THE FRONTAL GANGLION IN THE FEEDING AND ECLOSION BEHAVIOROF THE MOTH MANDUCA-SEXTA

We have examined the musculature and motor patterns of the foregut and the role of the frontal ganglion in the adult moth Manduca sexta, Dur ing adult development, the structure of the foregut changes from a sim ple straight tube to a pump consisting of a flexible-roofed chamber or cibarium, with dilator muscles that raise the roof to draw in fluids and a compressor to push it down and force the fluid down the thin-wal led esophagus, The frontal ganglion drives the activity of this cibari al pump during feeding, which is triggered by the application of sucro se solution or water to the proboscis, The feeding motor pattern consi sts of coupled bursts of the pump dilators and shorter-duration, high- frequency bursts of spikes from the pump compressor. The pump is also activated at the adult molt. At this time, it is used both before the moth emerges from the pupal case for swallowing molting fluid and agai n after emergence for swallowing air. These behaviors are important fo r eclosion and are necessary for the expansion of the wings after eclo sion, Their motor patterns are similar to the feeding program. Up to 2 4 h before adult ecdysis, this motor pattern can be triggered by the p eptide eclosion hormone. The other eclosion-related peptide, Manduca s exta eclosion-triggering hormone, does not appear to trigger activity of the cibarial pump.