The long-standing wisdom holds that insects or other invertebrates do not require vitamins D and K. Vitamin A is involved in many mammalian tissues, mostly in ways not completely understood. One well-appreciated action of this nutrient is its role in vision. We will discuss the physiology of vision in a later lecture, in which the role of vitamin A will be addressed in detail. For now we will just make the point that vitamin A is required for insect vision. Vitamin E is also thought to be dietarily essential in at least some insects.
Vitamin E is essential for fertility in rats, and apparently in male crickets.
The specific roles of vitamin E are not understood, although its most well known activity is its action as an antioxidant. Vitamin E is thought to interact with certain free radicals, and thereby prevent oxidative damage to cells. Whether vitamin E is required by all insects is difficult to say. I speculate it is required, however, the requirement is very hard to detect because the vitamin is stored in tissues and turns over only very slowly. Now there is one last problem in energy metabolism.