Yellow mealworm, Tenebrio molitor, reared on fruit-waste supplemented substrates: a promising aquafeed ingredient

The growing demand for sustainable and cost-effective protein in aquaculture has intensified the interest in edible insects, with mealworm (Tenebrio molitor) larvae recognized as a promising alternative due to their high protein content and ability to thrive on low-cost substrates. This study investigated the nutritional enhancement of T. molitor larvae reared for a period of 12 weeks on wheat bran (WB) supplemented with fruit wastes such as pineapple peels (PP) and watermelon rinds (WR). Five substrates were prepared as: WB (control), WB/PP (1:1); WB/WR (1:1); WB/PP/WR (1:1:1) and PP/WR (1:1). The insects were reared on experimental diets for 12 weeks of feeding period. Proximate, mineral, and amino acid profiles were analyzed. Crude protein ranged from 41.83% (WB) to 46.35% (WB/WR), with no significant differences in moisture, fat, and carbohydrate contents, but significant differences in ash, crude fiber, and protein levels. Larvae reared on WB/PP/WR had higher calcium, manganese, and sodium, while WB-fed larvae had higher iron, magnesium, and phosphorus. The amino acid profile varied with substrate, with WB/WR larvae recording the highest levels of histidine, threonine, leucine, tryptophan, asparagine, glutamic acid, cystine, alanine, glutamine, and arginine. Overall, fruit waste supplementation improved the nutritional quality of T. molitor larvae, with WB/WR exhibiting the most favorable amino acid and protein profile, supporting their potential as sustainable protein ingredients in aquafeeds.