“VALORIZATION OF COMPOST DERIVED FROM THE PRODUCTION OF HERMETIA ILLUCENS LARVAE FOR USE IN THE DEVELOPMENT OF NEW PLANT SUBSTRATES WITH ADVANCED FEATURES”

The main objective of this project, which has been carried out throughout the year 2022, is the evaluation and experimental development of a new process for the transformation of agro-food by-products and wastes, specifically the frass resulting from the production of the black soldier fly (Hermetia illucens), in such a way that its valorization is achieved by reducing its electrical conductivity through its inclusion in the formulation of other substrates as a substitute for fertilizers and chemical additives, which will allow obtaining from this by-product new ideal substrates of advanced performance for the development and production of high quality plants of ornamental type, as well as for seedbeds and propagation nurseries.

In addition, to ensure the success of the project by achieving this general objective, a series of specific-technical objectives were defined, which are detailed below:

• Study and analysis of frass resulting from the production of the larva of Hermetia Illucens according to different products used as food for it, in order to determine its validity as an ingredient for new substrates.
• Define and develop new formulations and prototype substrates that include larval frass as an ingredient to replace other fertilizers and chemical additives.
• Characterization of the new prototype substrates in order to determine their physical-chemical characteristics and whether their electrical conductivity is suitable for use in ornamental plants as well as in seedbeds and propagation nurseries.
• Validation of the new prototype substrates with larval frass in seedling and nursery stages, both at pilot level in a laboratory under controlled conditions and in the field, in order to determine the interactions between the physical-chemical properties of the substrate and the effects induced at plant level, showing the improvement of the performance of these substrates.

The main innovative element has resided in the formulation of the new substrates itself, since for the first time it will include fertilizing substances such as nitrogen, phosphorus or potassium derivatives from both the digestion and excretion process of the larvae and their decomposition process, i.e. biostimulant and elicitor substances that will help the plants to improve their root and aerial development as well as their immune system.

These biostimulant and elicitor substances are chitin and chitosan from the exoskeleton of the larvae after their decomposition, which have demonstrated their multiple beneficial effects in agricultural activities such as their protective activity for the control of pests and diseases caused by bacteria, fungus and nematodes, by producing biocidal metabolites and activating defense mechanisms in the plant, fertilizing effect, acting as an adjuvant to improve the effectiveness of other biocontrol agents, stimulating growth and increasing the productivity of ornamental crops, and improving water retention in the soil; and hemicellulose, cellulose and lignin fibers that will not only help the growth of the root system generating higher quality seedlings in a shorter period of time but will also make them more resistant to possible transplanting.

In this sense, the main novelties and substantial technological advantages that the innovative solution proposed brought in the form of the new substrates to be developed can be encompassed in the following aspects:

• Increased vegetative growth..
• Increased root system development.
• Increased flowering.
• Increased absorption and mobility of nutrients.
• Increased lignification and suberization of the plants.
• Increased synthesis of biochemical compounds beneficial for the plant. 
• Decrease in abiotic stress. 
• Decrease in the spread of diseases between plants and within the same plant.
• Decreased impact of fungal, bacterial and viral attacks.
• Decreased impact of insect and nematode attacks.