Self-Selection of Agricultural By-Products and Food Ingredients by Tenebrio molitor (Coleoptera: Tenebrionidae) and Impact on Food Utilization and Nutrient Intake

Abstract

Nutrient self-selection was used to determine optimal intake ratios of macro-nutrients by Tenebrio molitor L. larvae. Self-selection experiments consisted of 9 combinations (treatments) of 8 ingredients, from a total of 20 choices, radially distributed in a multiple-choice arena presented to groups of 100 T. molitor larvae (12th–13th instar). Larvae freely selected and feed on the pelletized ingredients for a period of 21 days at 27 °C, 75% RH, and dark conditions. Consumption (g) of each ingredient, larval live weight gained (mg), and frass production were recorded and used to calculate food assimilation and efficiency of conversion of ingested food. The macro-nutrient intake ratios were 0.06 ± 0.03, 0.23 ± 0.01, and 0.71 ± 0.03 for lipid, protein, and carbohydrate, respectively on the best performing treatments. The intake of neutral detergent fiber negatively impacted food assimilation, food conversion and biomass gain. Food assimilation, food conversion, and biomass gain were significantly impacted by the intake of carbohydrate in a positive way. Cabbage, potato, wheat bran, rice bran (whole and defatted), corn dry distillers’ grain, spent brewery dry grain, canola meal and sunflower meal were considered suitable as T. molitor diets ingredients based on their relative consumption percentages (over 10%) within treatment.

The Effect of Substrate on the Nutrient Content and Fatty Acid Composition of Edible Insects

“…However, in the study by Zhang et al [ 34 ], no clear correlation between the nutritional composition of substrates and yellow mealworm was observed. Morales-Ramos et al [ 43 ] observed in their study that a macronutrient ratio of 0.23 protein: 0.06 lipid: 0.71 carbohydrate was optimal for growth of yellow mealworm, and the intake of carbohydrates was seen to increase the efficiency of growth, whereas the intake of neutral detergent fiber had a negative impact on growth.…”

Rearing Tenebrio molitor and Alphitobius diaperinus Larvae on Seed Cleaning Process Byproducts

“…Both species are approved as aquafeed ingredient in EU [ 12 ], whereas T. molitor was the first insect species to acquire an EU-wide approval for human consumption [ 13 ]. The upcycling and bioconversion of several organic side-streams and wastes by T. molitor has been studied by several studies [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. For instance, an olive pomace-enriched substrate up to 25% enrichment sufficiently supported T. molitor larval growth, providing a means for exploitation, as well as management, of the olive processing byproducts [ 22 ].…”

Potential of mealworms used in polyhydroxyalkanoate/bioplastic recovery as red hybrid tilapia (Oreochromis sp.) feed ingredient

“…The FCR (8.2) and efficiency of conversion of ingested feed (ECI) (12.2%) were as earlier reported 17 . Low feed consumption affects growth rate which in turn affects feed conversion to biomass 65 . Interestingly, cell-fed mealworms showed a higher protein and lower lipid content than wheat bran-fed mealworms, due to the higher protein content of C. necator H16.…”