Central nervous system regulation of finicky feeding by the blowfly.

Abstract

Finicky feeding refers to an animal's tendency to become more particular in accepting and choosing food as satiation is approached. We tested the hypothesis that finickiness in the blowfly is related to the balance between internal inhibition, generated by a full crop, and external sensory information, generated by oral chemoreceptor contact with food. Response thresholds to sucrose and sucrose/quinine mixtures were determined for blowflies at two different levels of food deprivation. The deterrent effect of a given quinine concentration on feeding depends upon the concentration of sucrose in the mixture and the animal's level of deprivation. Transection of the recurrent nerve that normally signals fullness of the crop releases central inhibition and leads satiated flies to accept higher concentrations of quinine mixed with sucrose than controls. The results of this study suggest that the central nervous system's set point for responding to sensory excitation by sugar, rather than sensitivity to quinine, peripheral or central, determines gustatory finickiness in the blowfly.