Quantitative dietary requirements of the beetle Trogoderma for cholesterol and choline

The quantitative dietary requirements for cholesterol and choline of Trogoderma granarium were investigated. The ‘cholesterol-sparing’ activity of several sterols and substituents for choline were also studied. Cholesterol in amounts of 0·031 and 0·062 mg/g diet did not support growth. Two mg cholesterol/g diet gave optimal growth. Lanosterol, isocholesterol, 6-ketocholesterol, and cholecalciferol did not act as sparing sterols in the presence of 0·015 and 0·03 mg cholesterol/g diet. Cholesteryl methyl ether and cholesteryl chloride inhibited the growth of Trogoderma larvae in the presence of normally sufficient amounts of cholesterol. Choline was shown to be essential in the diet and the growth of the larvae was directly proportional to the amount of choline. Optimal growth was obtained at a level of 50 μg choline/g diet. Choline could be only poorly substituted by triethanol amine, γ-butyrobetaine, and carnitine.