This project is designed to identify a chemical in the blood of an insect that alters its feeding behavior. It focuses on the frontal ganglion (FG) of the moth Manduca sexta, a part of the nervous system that controls the ingestion of food. The FG drives the activity of the first part of the gut, the foregut. In the caterpillar, the foregut is constantly moving, taking in food and moving it further down the gut. Disrupting the function of the FG greatly reduces the amount of food ingested by the caterpillar or adult moth. At specific times during the moth's life cycle, the activity of the foregut is altered. For example, when the caterpillar is preparing to molt, it stops feeding and the foregut stops moving for about 16 hours. A preliminary study found that this change in activity is triggered by a factor in the blood. In the current study, experiments, several biochemical procedures will be used to isolate and purify the factor(s) in the blood of molting insects that alters foregut activity. Further studies of how the factor(s) act on the FG and foregut to alter their activities will be initiated. This project addresses basic research questions and provides the potential for more practical applications. One of the most fundamental questions in neurobiology is how an animal's nervous system is modified to produce changes in behavior. The large identifiable neurons and relatively simple behaviors of insects have allowed investigators to carry out detailed analyses of alterations in the neural circuitry underlying insect behaviors. Identification of a naturally occurring factor that disrupts a critical component of feeding behavior may prove useful for the development of specific chemical controls of insect feeding.