Carbohydrates and lipids are the two major energy sources. All animals use these macronutrients for growth and survival. Insects use these molecules for molt, flight, migration, diapause, starvation, nutrition of the embryo, synthesis of sex pheromones, cuticular wax, and production of various defensive secretions. Working group 3 will describe the major cell types involved in lipid and carbohydrate metabolism, evaluate the nutritional requirements in terms of quality and quantity for the selected insect species, and establish the key genes involved in lipogenesis and glycogenesis. WG3 will particularly collaborate with WG1 to evaluate the effect of nutrient digestibility and with WG5 to redact the experimental protocols.