Symbiontic Interrelationships between Microbes and Ambrosia Beetles.1 III. Ergosterol as the Source of Sterol to the Insect2

In the absence of a mutualistic fungus, X. ferrugineus (F.) (Coleoptera: Scolytidae) pupated in the 2nd genoration on test diets which contained 0.2 g of ergosterol. Cholesterol at 0.2 g per diet batch was not an adequate source of sterol in the 2nd fungus-free generation. Those sterol requirements of the 1st fungus-free generation of the insect which were not in the diets apparently were met by carry-over of such nutrients from the previous generation (stock culture) fed fungus-containing diets.