The Nutrition of the Larva of Aedes Aegypti L. II. Essential Water-Soluble Factorb From Yeast

Abstract

1. Autolysis products of fresh brewer's yeast, tested for their ability to promote growth of larvae of Aedes aegypti, revealed the loss of an essential part of the activity of the original yeast. Under suitably modified conditions this loss could be avoided. 2. A basal medium comprising the water-insoluble factor of brewer's yeast, glucose, salt mixture and yeast nucleic acid requires supplementation with thiamin, riboflavin, nicotinic acid, pantothenic acid and possibly with biotin in order to permit larval growth to the fourth instar. 3. For pupation, one further factor appears to be necessary, namely, folic acid. Its effect is specific, for it cannot be replaced by xanthopterin or thymine. It exercises an important effect also on growth and survival rates, bodily pigmentation and size of the larvae. 4. The following substances when added to or withheld from various media did not appear to influence growth or survival of the larvae; other vitamins of the B group, amino-acids, purines, pyrimidines, glutathione, ascorbic acid and possibly vitamin K. 5. Transference of larvae from a folic acid-free medium to one containing the vitamin, and vice versa, revealed that the presence of folic acid seems to have its most vital effect during the third stage of larval life.