Relations between dietary proportions of nutrients, growth rate, and choice of food in the fly larva Agria affinis

Abstract

Larvae of the fly Agria affinis respond to varying dietary levels of glucose and of amino acids. Regardless of the glucose level, for instance, a certain balance of nutrients—namely about 2·25 per cent of amino acids and 0·5 per cent of glucose—was superior for larval growth and was chosen predominantly over a lesser level of amino acids (0·75 per cent) and over a greater level (6·0 per cent). Certain different levels of amino acids—for example, 2·0 and 4·0 per cent—resulted in equal rates of growth and choice, or selection. But, in other cases, though different levels—for example, 0·75 and 5·5 per cent—may result in equal rates of growth, they do not necessarily result in equal degrees of selection. Thus, some insight is provided into relations between dietary ratios of nutrients, growth rate, and choice of food, which may be useful as principles in any attempts at nutritional control of insect pests.