Ecological and Nutritional Studies on Coleomegilla maculate (Coleoptera: Coccinellidae) IV. Amino Acid Requirements of the Adults Determined by the Use of C14-Labeled Acetate

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Abstract
Fifty adult Coleomegilla maculata (De Geer) were fed on 250 ml of an aqueous solution of sodium acetate-1-C14 which contained 600 micrograms of the salt; total C14 was 10 microcuries. After 4 hr, the beetles were homogenized, the amino acids were extracted and separated by thin-layer chromatography, and the activity was measured, using a scintillation counter. Glycine, serine, aspartic acid, glutamic acid, proline, and lysine showed high activity, and are considered to have been synthesized in vivo. They are apparently nonessential, in contrast to threonine, phenylalanine, isoleucine, and valine, which are essential or derived exclusively from essential dietary constituents. The low activity shown by alanine, leucine, arginine, and histidine indicated a low level of C14 incorporation. Three unknown ninhydrin-positive compounds were isolated, in addition to the 19 amino acids that were identified.