The need for high levels of phenylalanine in the diet of Schistocerca gregaria nymphs

It has been demonstrated that an apparently good, nutrient-rich plant can be relatively short of phenylalanine for fifth-instar nymphs of Schistocerca gregaria. Supplementary phenylalanine invariably increased the efficiency of conversion of ingested food to body substance, showing that this was the limiting nutrient. Relatively large quantities of phenylalanine are required for cuticle protein over a few days in the first half of the instar, which is when this amino acid is at a premium.