Effects of diet on the chemical composition of migratory locusts (Locusta migratoria)

An experiment was conducted to determine the effects of diet on the chemical composition of migratory locusts (Locusta migratoria L.). Fresh and dry weight and the contents of dry matter, ash, lipid, protein, Ca, K, Mg, Na, P, Cu, Fe, Zn, retinol, lutein, zeaxanthine, cryptoxanthin, carotenes, lycopene and gross energy were determined in penultimate instar and adult locusts, that had been fed three different diets. The locusts received a diet of grass or grass+wheat bran or grass+wheat bran+carrots. Adding wheat bran decreased the protein content and increased fat content (633 vs. 583 and 182 vs. 231 g/kg DM, respectively). Addition of carrots to the diet increased fat content further from 231 to 271 g/kg DM. Mineral concentrations of Ca, K, Mg, and Na, were significantly affected by diet. P, K, Cu, and Fe concentrations were significantly different in penultimate migratory locusts compared with adults. Wheat bran decreased the α-carotene content, which did not change by incorporating carrots in the diet. However, carrots did result in higher β-carotene concentrations. Retinol concentrations were increased by incorporating both wheat bran and carrots in the diet compared with the diet containing only grass. This study shows that the chemical composition of migratory locusts can be manipulated through the diet. As such, it enables nutritionists to adapt the chemical composition of live feeder insects to better meet the nutritional demands of predators.