Utilization of sterols by larvae of Drosophila melanogaster

Abstract

Twenty sterols were tested for their ability to replace cholesterol in an axenic, defined diet for Drosophila melanogaster. Larval development rate, survival to eclosion, and weight were used as criteria of efficiency. Only sterols with an intact, planar ring structure, with a side-chain similar to that of cholesterol and with a 3β-OH grouping support full development. Phytosterols are superior to cholesterol; and Drosophila shows a pattern of sterol utilization similar to other phytophagous insects. Departures from this are discussed, including the ability of dihydrocholesterol to substitute for cholesterol. The limited ability of larvae to use desmosterol, althought they grow normally when this is supplemented with small amounts of cholesterol, is taken to confirm the view that sterols have a bulk and a micronutrient rôle in insect nutrition. Interstrain comparisons show that genotypic differences may influence ability to utilize various sterols.