Effects of two diets on adults’ survival and productivity in mass-rearing of Tenebrio molitor (Coleoptera: Tenebrionidae)

Yellow mealworm is a grain infesting pest that is receiving attention nowadays as an alternative protein source for humans and animals. Its ability to convert low quality feed, like organic by-products, into high-quality food increases its production sustainability. The feeding diet is one of the most important factors in rearing Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae), which affects its growth, longevity and nutritional composition. Many by-products have been tested on larvae, but studies are scarce on adults. This work aimed to compare the effect of chicken feed diet (C) and wheat bran (B) by-product, as well as integrating yeast (CY and BY), on the adults’ reproduction and larval growth. Experiment was set up in a complete productive cycle of mass-rearing. The evaluation was done on the reproductive stage of the adults and the development of the larvae until harvesting (appearance of the first pupa). Results showed that the bran-based diets significantly improved the adults’ survival; after 50 days, mean of 110 and 146 adults survived on B and BY diets respectively compared to mean of 23 adults when reared on both chicken feed diets. Besides, wheat bran supplemented with yeast improved the total number of larvae (6,448.2 larvae) compared to bran diet (4,016.7 larvae). Whereas the two chicken feed-based diets had significant positive effect on the average larval weight; the maximum weight reached was 116.3 mg and 145.8 mg for larvae read on C and CY diets respectively compared to 47.8 mg and 57.3 mg on B and BY diets. Nevertheless, in 50 days of reproduction, the total larval biomass was highest on bran supplemented with yeast (283.1 g). In conclusion, the increase of sustainability and efficiency in mass-rearing of mealworms is possible by using appropriate diets on respective stages; bran-based diets for reproduction and chicken feed-based diets for larval growth.