Amino Acid Synthesis from Glucose-U-14C in Argyrotaenia velutinana (Lepidoptera: Tortricidae) Larvae

Abstract

In previous studies using the dietary amino acid deletion technique, it was found that the insect Argyrotaenia velutinana (Walker) required the same 10 amino acids indispensable for the rat. To further verify the dietary amino acid requirements of this insect, amino acid synthesis from glucose-U-14C was investigated in the larval stage. For this, fifth-instar larvae were reared aseptically on a synthetic medium containing glucose-U-14C. The relatively high specific activity measurements for aspartic acid, glutamic acid, glycine, serine, alanine and cysteine indicate that the insect is capable of synthesizing these amino acids from glucose. Lysine, histidine, arginine, valine, methionine, isoleucine, leucine, phenylalanine and threonine showed low specific activity measurements; therefore, these amino acids are classified as nutritionally indispensable. These results agree with those obtained by the amino acid deletion technique. Although tyrosine showed no radioactivity it may be considered a dispensable amino acid because it was shown to be dispensable by the deletion technique, and its synthesis from phenylalanine has been demonstrated in other insects. Proline was shown to be dispensable by the deletion technique and the low specific activity measurement obtained for proline in this study was accounted for by dilution of the 14C with unlabeled components of the diet during the indirect synthetic route from glucose to proline.