[Nutritional budgets for third stage instars of Myzus persicae (Sulz.)]

A general equation is provided for the nutritional budgets of both morphal stages of third-instar larva of the green-peach aphid Myzus persicae (Sulz.), fed on an artificial diet. Uptake of food and oxygen is related to: 1) gain in (fresh) weight, 2) amount of excrement, 3) carbon dioxide respired, and 4) water lost by transpiration (Table 4).Aphids fed holidicly exhibit a respiratory quotient of 1.0 during food uptake, thus using mainly carbohydrates during respiration. Hence, based upon quantitative chemical analysis of the excrement, an equation for an amino acid or glucose budget can be formulated (Table 5). The energy budget can then be calculated from these equations (Table 6). The water budget (Table 7) of the aphids is derived from the equation of the general budget. These values confirm that the alatiform morphs differ from their apteriform sisters in the efficiency of their nutritional budgets.