MAXILLECTOMY DOES NOT DISRUPT SELF-SELECTION BY LARVAE OF MANDUCA-SEXTA (LEPIDOPTERA, SPHINGIDAE)

Manduca sexta (Johannson) larvae were maxillectomized early in the third instar, and as newly emerged fourth instars were permitted to feed by self-selection (i.e., offered the opportunity to feed selectively on a defined sucrose diet [lacking only protein], or a defined protein diet [lacking only sucrose]) through the entire stadium. They did not differ significantly in their self-selected protein/carbohydrate ratio from sham-operated control larvae. Further experiments were done in which similarly operated larvae and controls were preconditioned for 15 h on diets lacking either sucrose or protein, starved for 4 h, placed in a self-selection environment, and observed every 10 min for 5 h of a 7-h period as they made their choices between sucrose and protein diets. Larvae that had been preconditioned on a protein-free diet tended to associate with the protein diet, whereas those preconditioned on a sucrose-free diet spent their early hours on the sucrose diet. The behavior of maxillectomized larvae differed only in minor ways from that of the controls.