BLOOD TREHALOSE LEVELS HAVE A ROLE IN THE CONTROL OF DIETARY SELF-SELECTION BY HELIOTHIS-ZEA LARVAE

Heliothis zea (Boddie) larvae that fed on an optimal diet (80: 20 protein: sugar ratio) had low levels of blood trehalose. In contrast, blood trehalose levels were high when larvae fed on a diet with a greater sugar content. Blood trehalose was also elevated in self-selecting larvae that had been feeding ad libitum from the sugar diet and that, satiated with sugar, had voluntarily left the sugar diet to begin feeding on the protein diet. These larvae had been offered only the choice of a sugar diet (lacking protein) and a protein diet (lacking sugar). Larvae previously deprived of sugar in their diet subsequently showed a strong tendency to feed on a sugar diet if given a choice between a protein diet and a sugar diet. This tendency was abolished if trehalose was injected into the blood of sugar-deprived larvae. A physiological mechanism for the control of dietary self-selection is proposed.