TenEDEN: Efficient organic fertiliser from mealworm meal

The larvae of the flour beetle (Tenebrio molitor), colloquially known as the mealworm, are among the most economically important beneficial insects. They are rich in high-quality proteins, vitamins and omega-3 fatty acids. The mealworm is authorised as feed for aquaculture and livestock (excluding ruminants) as well as food. In addition to the insects themselves, mealworm farming produces another product: insect frass, a mixture of excrement from farmed insects, feed residues and parts of farmed insects. This frass has great economic potential as an organic fertiliser and contains bacteria and functional ingredients that can promote plant growth and soil life. However, in 2021, the EU regulation (Regulation (EU) 2021/1925) was adapted, according to which frass must be heated (hygienised) at 70°C for one hour to ensure microbiological safety before it can be sold as a fertiliser. However, this energy and cost-intensive targeted killing of microorganisms also decimates the beneficial bacteria, which can have an impact on the fertiliser properties. 

The project will take a closer look at frass as an organic fertiliser from an economic, sustainable and microbiological perspective in order to better control, characterise, market and use frass-based products. To this end, the influence of hygienisation is analysed in detail by comparing hygienised frass with untreated frass. The microbiological characterisation will focus on safety-relevant aspects such as contamination with potentially pathogenic germs. Furthermore, bacteria that support plant growth, e.g. through nitrogen fixation or phytohormone production, are to be identified. Together with our project partners, the differently treated Frass varieties will also be examined for inorganic plant nutrients and fertiliser effectiveness, and greenhouse gas balances will be determined.  

On the one hand, this knowledge should provide information on the extent to which the fertiliser potential is reduced by hygienisation. On the other hand, a better characterisation should help to ensure that, in the event of a long-term continuation of the hygienisation obligation, the harmless bacteria with a positive effect on soil and plants are known and characterised and can therefore be used in agriculture to improve the soil.