Vitamin Requirement of the American Flour Beetle Tribolium confusum Duval

Abstract

THE larvæ of the American flour beetle Tribolium confusum Duval can only develop on a diet consisting of protein, carbohydrate, salts, and water if yeast or some other suitable vitamin source is added¹. Fröbrich² found the addition of 5 percent of dry yeast to a diet of casein, rice starch and Osborne-Mendel salt mixture in a relative humidity of 70–75 percent to be sufficient. For the activity of the yeast extract thiamine, riboflavine, and an unknown factor B_x were important ; in the insoluble fraction there were recognized as necessary ergo sterol (which could be replaced completely by cholesterol) and a further unknown factor, U. Offhaus³ obtained similar results with a diet of dried egg-white, rice starch, and di-potassium hydrogen phosphate, but found that the insoluble yeast fraction could be completely replaced by cholesterol + histidin. Fraenkel and Blewett⁴ have also investigated this problem.