Composition corporelle en acides amines du parasitoide Phryxe caudata (Diptera) au cours de sa croissance larvaire

The analysis of amino acids in acid hydrolysates of whole larvae of the parasitoïd Diptera, Phryxe caudata, has permitted us to establish a relationship showing the quantity Q of each of the seventeen aminoacids measured, as a function of the fresh weight P of the larva. We have considered two kinds of relationships: allometric (Q = cP^d) and polynomial ones (Q = eP² + gP), these adapt most precisely to the whole field of study.Those relations show that the incorporation of the aminoacids in the living material is not exactly proportional to the weight of growing larva.Tyrosine, β alanine, phenylalanine, methionine, and histidine accumulate, whereas the ratios of the other aminoacids decrease during growth. Thus the relative needs of the larva in tyrosine are ten times greater at the end of growth than at the beginning.It has been also shown that, because of the very fast larval growth, the quantitative needs in aminoacids become considerable. The consequences of these facts are discussed in view of realisation of in vitro satisfactory nutritional conditions.The total protids, which are constant during growth (10% of the fresh weight) represent a half of the dry weight at the beginning of larval growth, but, because of the accumulation of non protidic reserves, (probably lipids) represent only one third, at the end of development.