Abstract:
Last instar larvae of the armyworm, Spodoptera exempta WALKER were given the opportunity to self-select from two defined diets, both complete except that one contained protein (casein) but no digestible carbohydrate (sucrose) and the other contained carbohydrate but no protein. The larvae ate the protein and carbohydrate diets in a ratio of 80:20. In general, the growth and efficiency of food use of the larvae were not significantly different between the self-selectors and that of the controls. When the larvae were provided with a nutritionally complete diet with a protein:carbohydrate (casein:sucrose) ratio of 80:20, 50:50 , or 20:80, they performed best in 80:20 diet, "the self-selected ratio" as compared with the 50:50 diet. The larvae grew very poorly in 20:80 diet, with all nutritional indices significantly inferior as compared to those of 80:20, or 50:50 diets.