Productivity and larval growth of Tenebrio molitor reared on differently composed diets of similar nutritional composition

Abstract

The artificial diet of Tenebrio molitor has been a focal point of many studies that aimed to design the best diet combination. Recently, studies are focusing on the use of by-products and their efficiency as diets for rearing T. molitor. The rearing was successful on a wide range of by-products-based diets. The feed has a profound impact on the lifespan, growth, productivity and nutritional composition of T. molitor. Productivity is one of the traits highly influenced by the diet’s composition, especially macronutrients. This work aims to study the effect of eight different diets on the weight and productivity of females and their progeny weight: larval weight. Wheat bran, brewer’s yeast, spent grain and bread remains were used to compose the diets, based on different inclusion percentages of each by-product. The nutritional composition, mainly the macronutrients, of the diets had a narrow range of differences. The diets were designed in a way to avoid the effect of different nutritional compositions and study the effect of the by-products type only. Results showed that the female’s weight-change during the egg-laying period was not significant under different rearing diets. Moreover, the female’s productivity measured by the larval number showed no significant difference between the different diets. However, the total larval biomass (452.4 mg) was significantly higher for larvae reared on diet A composed of wheat bran and brewer’s yeast. Also, the total mean larval weight was significantly higher for larvae reared on diets A (3.1 mg) and G (3.2 mg) composed of wheat bran, brewer’s yeast and spent grain. The mentioned diets although composed of different by-products have similar amounts of protein and carbohydrates. These results prove that the type of by-products included in the experimental diets does not affect the reproductive performance of T. molitor, while it can affect larval growth.