Protein nutrition of Tenebrio molitor L. XX. Growth response of larvae to graded levels of amino acids

Abstract

Larvae of Tenebrio molitor L;, Gembloux strain, race F, having an average initial weight of 10 mg were reared for 4 weeks at 27 +/- 0.25 degrees C and 65 +/- 5% relative humidity on diets containing an amino-acid mixture resembling the composition of larval tissues; Each of 14 amino acids was tested individually at levels of 0, 10, 20, 50, 100 and 200% of the amount found in larval tissues, while the concentration of other amino acids remained constant. Diets were maintained isonitrogenous at 1.6% nitrogen with supplementary glutamic acid, glycine, serine and tyrosine; Maximum fresh weight gains and dry weights were achieved by larvae fed reference levels of all essential amino acids except phenylalanine, threonine and tryptophan. Maximum growth was achieved by larvae fed 50% of the phenylalanine level found in larval tissues, Threonine and tryptophan were the limiting amino acids in this study and are probably required in the diet in excess of twice the concentration occuring in larval tissues, Probable ranges for quantitative amino-acid requirements of T. molitor were determined and suggestions were made for improving the nutritional adequacy of the amino-acid mixture.