Amino acid requirements of Hypoderma bovis (L.), determined with glucose-U-14C

A radioactivity method that has been used to determine certain nutritional requirements of other insects was applied to third-instar larvae of Hypoderma bovis (L.). The larvae were squeezed from backs of infested calves, injected with glucose-U-¹⁴C, and held at room temperature for 37 hours. ¹⁴CO₂ was expired by the larvae showing that the sugar was metabolized. Concentrations of some of the amino acids in tissues of the grubs were determined. The amino acids were isolated and purified by column and band-paper chromatography. Alanine, proline, aspartic acid, and glutamic acid were shown to contain radioactive carbon. Since these compounds were readily synthesized, they are considered to be nutritionally nonessential for the cattle grub. The absence of radioactivity in phenylalanine, tyrosine, leucine, histidine, lysine, isoleucine, valine, and threonine show that these amino acids are not synthesized by the cattle grub from glucose and are probably nutritionally essential. Methionine also appears to be essential. Limited biosynthesis of glycine, arginine, and possibly serine by this insect suggests that it would benefit from a dietary supply of these compounds.