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

Abstract

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, α-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.

The fatty acid composition of edible grasshopper Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) feeding on diversifying diets of host plants

“…Several studies have shown that fatty acid composition in insects varies due to age, stage of development, reproductive activities, insects' state of health and, most importantly, diet (Finke ; Lehtovaara et al . ; Perez‐Mendoza et al . ; Sihamala et al .…”

“…In feeding, the insects and generally all animals aim at their 'nutrient intake target' (Fielding & Defoliart 2008), in order to allow them to fulfill their physiological functions such as reproduction. Several studies have shown that fatty acid composition in insects varies due to age, stage of development, reproductive activities, insects' state of health and, most importantly, diet (Finke 2013;Lehtovaara et al 2017;Perez-Mendoza et al 1999;Sihamala et al 2010).…”

“…Thus, the selected feeds for rearing R. differens, should be optimized to improve the nutritional content, especially for the PUFAs. In our previous study, we found that rearing R. differens on various artificial diets with manipulated fatty acid, carbohydrate and protein content significantly altered the content and composition of fatty acids in R. differens, including the essential linoleic (omega 6) and α-linolenic (omega 3) fatty acids (Lehtovaara et al 2017). However, the effect of plant diet diversification on total lipid content and composition of fatty acids in R. differens has not been explored.…”

“…In insects, the fatty acid compositions are dependent on species, developmental stage, rearing conditions, sex, metabolic activity, and, most importantly, diet (Bozkus ; Dadd ; Lehtovaara et al . ; Oonincx et al . ; Sönmez et al .…”

“…Fatty acids are biologically important in key life processes such as metabolic energy storage, cell structure and membrane function, temperature acclimation, cell signaling, and immune system function (Bikshapathy et al 2011;Hixson et al 2016;Stanley-Samuelson et al 1988). In insects, the fatty acid compositions are dependent on species, developmental stage, rearing conditions, sex, metabolic activity, and, most importantly, diet (Bozkus 2003;Dadd 1973;Lehtovaara et al 2017;Oonincx et al 2015;Sönmez et al 2016;van Broekhoven et al 2015). Most insects synthesize certain fatty acids such as palmitic acid de novo, from plant sugars and amino acids (Stanley-Samuelson et al 1988).…”