The chemistry of insect hemolymph. III. Glycerol.

Free glycerol has been identified as a major solute in plasma of pupae of the silk moth, Hyalophora cecropia. Glycerol is not found in the blood of larvae; it appears about the time of pupation, and then gradually accumulates during diapause to reach after 6 months a level of about 0.3 M. When diapause is broken and the adult develops, glycerol rapidly disappears. In diapausing pupae of the related species, Telea polyphemus, about 0.05 M glycerol was found; in 3 other saturniid species, there was little or none. It is suggested that glycerol may be a product of a modified glycolytic pathway.