Metabolic pathways of steroids in insects

This paper discusses sterol metabolism and utilization in insects with particular emphasis on the two known major metabolic pathways for steroids in insects: (1) The conversion of C28 and C29 plant sterols to cholesterol, including a comprehensive survey of the intermediates involved in the conversion of phytosterols to cholesterol, certain inhibitors of phytosterol metabolism, and the end products of sterol metabolism in insects. (2) The biosynthesis and metabolism of the steroid moulting hormones of insects (ecdysones), including the present state of our knowledge of the sterol precursors of the ecdysones, the ecdysteroid intermediates in their biosynthesis, and the inactivation of the ecdysteroids in insects. The biological and physiological significance of these metabolic pathways in insects is discussed, as well as their relationship to analogous pathways in plants and vertebrates.