Nutritional requirements for reproduction and survival in the blowfly, Lucilia sericata

Insects with access to finite energy resources must allocate these between maintenance and reproduction in a way that maximises fitness. This will be influenced by a range of life-history characteristics and the environment in which any particular insect species lives. Here females of the blowfly, Lucilia sericata (Diptera: Calliphoridae), were fed diets differing in protein and carbohydrate (sucrose) content, and the allocation of lipid to reproduction was quantified using a spectrophotometric method of analysis. Immediately after adult emergence, total body lipid, scaled for differences in body size, showed an initial decline as it was utilised to meet the metabolic demands of cuticle deposition, muscle maturation and then flight. When flies were denied access to sucrose, stored lipid then continued to decrease until flies died, usually within four days of emergence. However, flies given access to sucrose were able to increase body lipid content, demonstrating that carbohydrate is essential for homeostasis and that it can be used to synthesise lipid. Nevertheless, female flies fed sucrose only were unable to synthesise egg yolk. Only flies provided with protein were able to mature eggs. However, the rate of egg maturation and number and size of eggs matured were greater for female flies given liver compared to flies provided with pure whey protein powder. The results demonstrate the importance of different dietary components for different elements of the life-history of L. sericata, namely survival and reproduction.