The control of spontaneous locomotor activity in Phormia regina Meigen—I. Locomotor activity patterns of intact flies

Abstract

Locomotor activity patterns of intact flies under various feeding and deprivation schedules were studied with a tilting-type actograph and suitable recording apparatus. Under conditions of constant darkness, adults of P. regina exhibit well-marked circadian rhythms in locomotor activity. Constant light eliminates these rhythms and locomotor activity increases with deprivation time until the decline associated with the depletion of energy stores prior to death from starvation. When deprived flies are fed to repletion on sucrose solutions, locomotor activity is immediately and markedly depressed. Upon subsequent deprivation, activity increases at a rate dependent upon the concentration of the sugar ingested. The shape of the locomotor activity curve with deprivation is more dependent upon the frequency of periods of locomotor inactivity than upon the actual speed of movement involved. These observations suggest an on: off switching mechanism activated by the presence or absence of foodstuffs in some portion of the alimentary tract as the mechanism controlling spontaneous locomotor activity in relation to nutritional state.