The juvenile hormone analogue, pyriproxifen, alters protein and fat composition of Tenebrio molitor larvae

Maximising the yield of product from livestock is common practice in the agriculture industry and there is potential to extend this practice to the emerging insect industry, to produce high-quality, sustainable protein. Tenebrio molitor larvae, commonly called yellow mealworms, were fed for 28 days on wheat bran containing the juvenile hormone analogue, pyriproxifen at either 2 mg pyriproxifen/kg wheat bran (JH-PL) or 15 mg pyriproxifen/kg wheat bran (JH-PH). As expected, pupation was inhibited in both pyriproxifen treated groups and significant changes in nutritional composition were observed. Pyriproxifen treated mealworms had a higher protein content per 100 grams of dried material, while fat content was reduced 68% in JH-PH compared to control. These changes were associated with an increase in moisture content and reduction in energy content. The fatty acid profile of extracted fat also displayed significant alterations, with pyriproxifen treated mealworms showing an increase in proportions of saturated fatty acids, reduction in oleic acid but no effect on linoleic acid. The amino acid composition also exhibited a change in composition as a result of pyriproxifen treatment, including an increase in the essential amino acid, lysine, in JH-PH treated mealworms. This change in amino acid profile was associated with a change in the protein composition as observed on SDS-PAGE, with the appearance of a new band identified as the egg-yolk protein, vitellogenin, which has lipid-transporter activity. Hence, pyriproxifen treatment of mealworms has a repartitioning effect, resulting in an increase in the proportion of protein and a decrease in fat on a dry matter basis, demonstrating that mealworm nutrient composition can be manipulated to provide a higher value feed ingredient.