ASPECTS QUANTITATIFS DES BESOINS EN MINÉRAUX DE TRIBOLIUM CONFUSUM DUVAL: II. POURCENTAGE OPTIMUM DES CATIONS Mg, Ca, Na et K

The quantitative requirements of the Tribolium confusum larvae for magnesium, calcium, sodium, and potassium are reported. Magnesium and potassium are definitely essential for larval growth. Without these elements, the larvae do not survive long. Calcium appears essential for imaginal metamorphosis. In its absence, rapid dehydration of the pupae occurs and emergence of the adult is practically suppressed. The importance of sodium could not be demonstrated because the minute quantities already present in the basal diet appear sufficient to meet the requirements of this insect. The requirements of both sexes for these cations are of the same order of magnitude. Additions of these cations in excess of the optimum values are well tolerated.

ASPECTS QUANTITATIFS DES BESOINS EN MINÉRAUX DES LARVES DE TRIBOLIUM CONFUSUM DUVAL: I. POURCENTAGE OPTIMUM D'UN MÉLANGE SALIN

The quantitative requirements of the larvae of Tribolium confusum are studied. For optimal growth, the larvae require 1% to 8% of salt mixture No. 2 U.S.P. XIII. For the imaginal metamorphosis, we must add at least 2% of the salt Mixture. The requirements of the male and female are absolutely identical.

ÉTUDE BIOCHIMIQUE DE LA MÉTAMORPHOSE DE TRIBOLIUM CONFUSUM DUVAL (COLÉOPTÈRE: TÉNÉBRIONIDAE): I. VARIATIONS DU POIDS CORPOREL, DE L'HUMIDITÉ, DE LA MATIÈRE SÈCHE ET DES CENDRES TOTALES

The variations in the total body weight, water content, dry weight, and total ash of Tribolium confusum during metamorphosis are reported. A drop in total body weight before the insect enters pupation is observed. The pupal stage shows a moderate but sustained decrease in body weight followed by a further large one at emergence. Though the water content falls during the prepupal stage and at the emergence, there is a moderate increase in the water content during the pupal stage. These changes show that the pupae utilize the reserves accumulated during the larval stage. Variations in both dry weight and total body weight are similar. A study of simple correlation of these variables is discussed. The elimination in the prepupal stage of a large amount of the inorganic constituents (ash) is noticed. During the pupal stage, total ash remains constant while at emergence, there is a slight fall.

NUTRITION DES LARVES DE TRIBOLIUM CONFUSUM DUVAL: I. RECHERCHE D'UN RÉGIME SYNTHÉTIQUE BASAL SATISFAISANT LEURS BESOINS NUTRITIFS

A purified diet suitable for the study of the qualitative amino acids requirements of the larvae of the Coleoptera Tribolium confusum is presented. The composition of the diet is as follows: amino acid mixture 20%, cornstarch 75.5%, cholesterol 1%, wheat germ oil 1.5%, salt mixture No. 2 U.S.P. XII 2%, yeast 0.5%, vitamin mixture M.V.–II. In presence of amino acids, glucose cannot be used as a source of hydrocarbon. The mixture is very hygroscopic, develops a brown color, and is apparently toxic to the larvae. The importance of choline as a growth factor is demonstrated. Wilson's Liver Fraction L or Liver Concentrate 1: 20 cannot replace this vitamin. Yeast appears to contain unknown factors for it improves growth when added to a diet already supplemented with vitamins known to be essential for the larvae. A mixture of 19 crystalline amino acids known to occur in casein satisfies the nitrogen requirements of the larvae of T. confusum equally as well as purified casein.

NUTRITION DES LARVES DE TRIBOLIUM CONFUSUM DUVAL: II. IMPORTANCE DES ACIDES AMINES

The normal pupation period of Tribolium confusum on whole wheat diet averages 18 days. In presence of a purified diet containing 19 crystalline amino acids known to exist in casein, the pupation period is increased to 28 days. Removal of one of the amino acids considered as nonessential for growth in the rat from such a diet, results in pupation periods falling between 26 and 32 days. On the other hand, omission of lysine, threonine, phenylalanine, methionine, isoleucine, and arginine, one at a time, increases the pupation period from 61 to 70 days. If valine, tryptophane, histidine, or leucine are left out singly, pupation is prevented, though two-thirds of the larvae survive. It is concluded that the amino acids known to be essential for growth in the rat are also essential for growth and pupation of the larvae of T. confusum. Four of these essential amino acids appear to be connected with the phenomenon of pupation.

FURTHER WORK ON THE NUTRITION OF DUCKLINGS: A.—LIPOTROPIC FACTORS. B.—SULPHUR AMINO ACID REQUIREMENTS

Using a purified diet deficient in choline and containing 18% casein, it has been found that in the duckling: (a) betaine and aminoethanol have little or no lipotropic activity, are poor growth factors, and cannot prevent perosis; (b) monomethylaminoethanol and dimethylaminoethanol, on the other hand, have well marked lipotropic activity. Both substances stimulate growth and are antiperotic, dimethylaminoethanol being the most active of the two in these respects; (c) ducklings, like chicks, appear unable to methylate aminoethanol to any extent; (d) a level of 28% casein is more satisfactory than one of 18% in the prevention of fatty infiltration of the liver in ducklings.Betaine and methionine have a definite lipotropic activity, when fed to ducklings along with a semipurified diet containing peanut meal as the only natural ingredient. The substitution of yellow corn meal to sucrose in the above semipurified diet inhibits the lipotropic activity of methionine, without affecting that of betaine.The availability of a protein low in sulphur amino acids has resulted in the preparation of a more hypolipotropic diet. On this diet, ducklings presented livers containing, on the average, 24% of lipids. Methionine added to this diet is strongly lipotropic, but is without effect on growth. Methionine will promote growth only in presence of choline.Ducklings like chicks and poults appear to be able to convert methionine to cystine. In presence of 0.4% cystine, approximately 0.5% methionine is required for normal growth.

LIPOTROPIC ACTIVITY OF CHOLINE, BETAINE, AND METHIONINE IN DUCKLINGS

A purified diet, deficient in choline and containing 18% casein, results in fatty infiltration of the liver in ducklings killed at four weeks. Total liver lipids is about 13%, the normal value being 6 to 7%. Addition of 0.1 or 0.3% choline chloride results in nearly normal livers. In this respect, ducklings differ from chicks and are comparable to rats and dogs. Betaine has a slight lipotropic activity but does not stimulate growth and has no antiperotic properties. DL-methionine, when added to a purified diet containing 9% casein or to a simplified diet containing 15% casein, has no lipotropic activity. On the contrary, this ammo acid increases the total lipids and the severity of fatty infiltration of the livers. Choline has a triple function in ducklings; it promotes growth, prevents hepatic fatty infiltration, and perosis.