By Maja Berden Zrimec
The alarming rate of global waste production and the escalating demand for animal protein sources have created two pressing environmental and food security challenges. Surprisingly, the solution to both may lie in something as tiny as insect larvae. Insect bioconversion has emerged as a sustainable, economically viable, and environmentally friendly solution for managing livestock and poultry manure. These larvae can effectively process various organic waste materials and by-products, converting them into valuable insect-based products and upcycling organic matter into the food system.
Nutritious feed for farmed animals
Insects in general are precious reservoirs of proteins, fatty acids, micronutrients and contain high amounts of energy. They have a good profile of amino acids, including the most-limiting essential ones like lysine, threonine, and methionine, often lacking in plant-based protein sources for non-ruminants (1). One of the most promising applications of processed insect larvae is thus in animal feed. The abundance of protein makes larvae a potential substitute for fishmeal and soy-based feeds in aquaculture, poultry, and swine farming. They can also be processed into a protein-rich flour, suitable for pet food or as a supplement in human diets, thereby contributing to a more circular economy in our food systems.
One species that stands out for its efficiency is the black soldier fly (Hermitia illucens L.), a cosmopolitan tropical fly belonging to the Stratiomyidae family (Diptera). The dry weight of black soldier fly larvae contains up to 50% crude protein, up to 35% lipids and have an amino acid profile that is similar to that of fishmeal (1). They have a good profile of essential amino acids, with prevailing of leucine, lysine, valine, and histidine (1,2). Their content of saturated fatty acids exceeds that of the unsaturated fatty acids, and they contain vitamins like B1 and B2. Minerals such as calcium, potassium, phosphorus, sodium, magnesium, zinc, iron, manganese, and copper were found to be in adequate amounts in different larvae feed products tested by Zulkifli and co-workers (2).
Bioconversion of organic waste
The biological process of black soldier fly larvae involves their voracious consumption of organic waste, including fruit and vegetable scraps, manure, and even brewery waste. As they feed, they grow rapidly and convert the nutrients in the waste into high-quality protein within their own bodies. Their bioconversion process helps recycle nutrients, reduce noxious odours, lower carbon dioxide emissions, eliminate pathogenic bacteria, and decrease the need for antibiotics. For instance, poultry litter, a valuable resource with high nutrient content, can be effectively processed by black soldier fly larvae to reduce environmental contamination.
Black soldier flies have a short life cycle of around 40-50 days and a high reproductive potential, with each female capable of laying nearly 500 eggs (3). Consequently, they can modify physical, chemical, and biological properties of manure and reduce organic waste accumulation by up to 50% in a short period (few weeks) (3). In addition to feed, their biomass can serve as a source of fatty acids for biofuel, minerals, chitin, and chitosan for the production of various bio-based products (3).
Several studies have demonstrated the effectiveness of black soldier fly larvae in bioconversion processes. For example, the treatment of brewery-spent grain with black soldier fly larvae resulted in a significant increase in larval production and a 21% increase in nitrogen retention in frass fertilizer, achieving a 195% increase in the biomass conversion rate compared to the control (4). Another study showed that black soldier fly larvae bioconversion of soybean dregs with biochar reduced ammonia emission by 18.0% and increased nitrogen in frass by 35.0%, confirming the feasibility of biochar as an amendment for the black soldier fly larvae-based bioconversion system (4).
Can companies adapt the insect bioconversion technology?
Despite its potential, the widespread adoption of this technology faces several barriers. Regulatory challenges exist in many parts of the world concerning insects as feed or food as well as regulatory constrictions for using organic waste in biomass production (5).
Integrating insect larvae conversion into a company’s operations presents an innovative approach to sustainability, transforming organic waste into valuable resources. However, this process is not without its complexities. Companies must navigate regulatory challenges, as the legalities of using insects for waste management and their subsequent use in the food or feed chain differ across jurisdictions, often requiring considerable time and resources for compliance. Establishing this system demands specialized infrastructure for breeding, rearing, and processing insects at a commercial scale, alongside substantial upfront investment. Staff training is necessary to ensure proper handling of insects, system maintenance, and management of biosecurity risks, which might initially slow operations and inflate costs. While insect larvae can process a significant waste volume, scaling this process for industrial waste quantities might pose challenges, potentially necessitating supplementary waste management strategies. Furthermore, the economic viability of this venture depends on a viable market for the end products – protein-rich larvae and residual organic fertilizer – which varies across regions and sectors.
Public perception of using insect larvae for waste processing also plays a crucial role, as negative associations could affect customer reception. Finally, if allowed to use waste stream, its composition must be consistent and suitable for larvae, as not all organic wastes are appropriate, and some may even be harmful. Companies contemplating such a venture should conduct a thorough feasibility study to understand potential returns, regulatory constraints, infrastructure needs, and market prospects. In many cases, partnering with existing insect processing enterprises as part of a broader waste management strategy could be more beneficial than creating independent infrastructure.
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References
- Shumo, M., Osuga, I.M., Khamis, F.M., Tanga, C.M., Fiaboe, K.K.M., Subramanian, S., Ekesi, S., van Huis, A., Borgemeister, C. (2019): The nutritive value of black soldier fly larvae reared on common organic waste streams in Kenya. Scientific Reports 9:10110. https://doi.org/10.1038/s41598-019-46603-z
- Zulkifli, N.F.N.M., Seok-Kian, A.Y., Seng, L.L., Mustafa, S., Kim, Y.-S., Shapawi, R. (2022): Nutritional value of black soldier fly (Hermetia illucens) larvae processed by different methods. PLoS ONE 17(2):e0263924. https://doi.org/10.1371/journal.pone.0263924
- Pushpalatha, M., Gadge, A.S., Bankar, D.R. (2023): Treasure out of trash – black soldier fly. Insect Environment Vol. 26 (1):57-64. Doi: 10.55278/QFAB1574
- Zhang, H., Zhang, X., Chen, M., Deng, X., Pei, Y., Zhang, J., Chen, H., Yang, S. (2023): Biochar Can Improve Absorption of Nitrogen in Chicken Manure by Black Soldier Fly. Life 13: 938. https://doi.org/10.3390/life13040938
- Fera workshop (2023): Is Insect Bioconversion a Route to Delivering Sustainable & Safe Products for the Petfood Industry?
