Due to increasing welfare and population, the demand for alternative protein sources, obtained with minimal use of natural resources, is rising in today’s society. Insects have the potential to be used as an alternative protein source since they are considered to be able to convert low-value biomass into high-value components, resulting in opportunities for valorisation of organic side streams. Moreover, insects are suggested to be a sustainable protein source, referring to the efficient “feed to body” mass conversion potential. The aim of this review was to explore the potential to rear the yellow mealworm (Tenebrio molitor), the house cricket (Acheta domesticus) and the migratory locust (Locusta migratoria) on low or not yet valorised organic side streams within the food supply chain. This was performed by collecting research information focusing on the rearing of the insects in scope on organic biomass. In addition, the nutritional composition of the produced insects as well as their dietary requirements will be reviewed. Finally, the availability of side streams in the EU will be discussed as well as their potential to be used as insects feed.

Insect farming, a potential approach to deal with the increasing global protein demand, is a new activity in the Western world with many unanswered questions regarding product quality and safety. Insects may fulfill an important role in a circular economy by upcycling biowaste into valuable biomass. About half of the total mass of mealworm feeding substrates exists out of wet feed. This can be sourced from biowaste, increasing the sustainability of insect farming. This paper reports on the nutritional profile of yellow mealworm, Tenebrio molitor, reared with supplementation of organic sidestreams. These included unsold vegetables, potato cuttings, fermented chicory roots and horticultural foliage. The evaluation was performed by analyzing proximate compositions, fatty acid profiles, mineral and heavy metal contents. Mealworms fed with potato cuttings doubled their fat content and increased saturated and mono-unsaturated fatty acids. Providing fermented chicory roots increased the mineral content and accumulated heavy metals. Additionally, the uptake of minerals by mealworms was selective as only calcium, iron and manganese concentrations increased. Adding vegetable mix or horticultural foliage to the diet did not significantly change the nutritional profile. In conclusion, sidestreams were successfully recycled into protein-rich biomass and their nutrient content and bio-availability influenced the composition of mealworms.

Whereas the production of conventional livestock can rely on years of knowledge and experience, the mealworm production industry is still in its early stages. Although the yellow mealworm Tenebrio molitor has been cultivated as feed for pets and zoo animals for quite some time, the optimization of the reproduction process has not been widely explored. For reproduction, beetles are placed in crates supplemented with a substrate to oviposit their eggs. After a specified time, the beetles are removed, and the eggs are further cultivated to develop into larvae. Factors such as oviposition duration and beetle density influence the number of produced mealworms per beetle, partly due to the cannibalistic behavior of the beetles. However, reproductive success has mostly been assessed by determining the number of offspring several weeks after oviposition. As a result, the number of eggs laid and their hatch rates are unknown. In this research, eggs are separated from the oviposition substrate, i.e., harvested. This approach allows to determine the influence of beetle density, oviposition duration, beetle age and the use of a grid during oviposition on the number of eggs produced and the egg hatching rate and timing thereof. In addition, the influence of the harvesting method on the hatching of T. molitor′s eggs was determined.