The fatty acid contents of the edible grasshopper Ruspolia differens can be manipulated using artificial diets

Edible insects have been suggested as an alternative and sustainable source of fats, proteins and vitamins for humans. However, their nutritional content may largely depend on the diets offered for insects. Diet-based manipulation of fatty acids in edible insects shows promise to possibly increase their essential and long-chained polyunsaturated fatty acid content and thus further enhance human diets. We reared the edible grasshopper, Ruspolia differens, under various diets with manipulated content of fatty acids, proteins and carbohydrates. The manipulated diets dramatically altered the insects' content and composition of fatty acids, especially the content of polyunsaturated fatty acids. Dietary fatty acids were stored largely unaltered in insects. Artificial diets with high content of linoleic, a-linolenic, eicosapentaenoic or docosahexaenoic acids, increased the content of these fatty acids in the insect tenfold. The manipulated diets also affected the omega-6/omega-3 (n-6/n-3) fatty acid ratio and developmental performance. Lack of protein and fats in the diet prolongs the development and leads to lower final weight. To achieve required n-6/n-3 ratio for human consumption and to maximise biomass gain and weight, diverse diets with a source of n-3 fatty acids and protein should be used when rearing R. differens. These results demonstrate the potential for improving human nutrition in an effective and sustainable way by producing edible insects with designed nutritional content.