Wheat damage by Sitophilus granarius: impact on nutritional value of Tenebrio molitor as an alternative feed

The use of Tenebrio molitor larvae as feed for monogastric animals is increasingly widespread. The nutritional value of these larvae, particularly their organic matter and protein content, directly influences animal growth performance, which is strongly affected by the larvae's own diet. This study investigated the use of wheat grains differently damaged by Sitophilus granarius as a substrate for rearing T. molitor . Four wheat samples were artificially infested with varying densities of S. granarius and incubated for one year to allow graded levels of damage. The resulting substrates were analysed for organic matter (Wendeii analysis) and amino acid composition. Subsequently, they were ground and used in a four-week feeding trial with T. molitor . Insect weight, length, feed conversion efficiency, and mortality were recorded throughout the experiment. At the end of the trial, the larvae were also subjected to organic matter and amino acid analysis to evaluate their nutritional composition. The results showed that T. molitor larvae reared on the most heavily damaged wheat exhibited the highest feed conversion efficiency and most favorable nutrient profile. This outcome is attributed to the omnivorous feeding habits of T. molitor , which likely benefited from the metabolic by-products and partially decomposed material in severely infested grains. These findings suggest that heavily insect-damaged stored products may represent a valuable substrate for rearing T. molitor , thereby adding potential value to otherwise wasted commodities and supporting sustainable insect biomass production. • Modified protein and amino acid composition caused by S. granarius in damaged wheat. • Endosperm-consuming S. granarius transforms carbohydrates into protein. • Feeding of insect-damaged lots ensured the optimal development of T. molitor. • Sitophilus damaged lots can be a good base for the rearing of omnivorous T. molitor .