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New FBN study provides insights into the carbon footprint of the black soldier fly
The larvae of the black soldier fly (Hermetia illucens) are considered a promising source of sustainable protein, as they contain high-quality protein comparable to soy protein. They can produce this protein from a wide variety of biomass sources, including by-products and residues from agriculture and food processing. However, while their potential is the subject of intense debate, little is known about the emission of greenhouse gases during their rearing.
A new study by the Research Institute for Farm Animal Biology (FBN), published in the journal Bioresource Technology (DOI: 10.1016/j.biortech.2025.133812), approaches this question systematically for the first time. The researchers investigated how the quality and nutrient composition of the biomass fed to the larvae affects their growth, body composition and gas emissions. Continuous measurements of carbon dioxide and ammonia gas emissions were taken during a sensitive phase of larval development, namely between the 9th and 16th day after hatching.
Growth, emissions and the question of the correct reference value
The results show that the profile of gas emissions depends largely on the quality and nutrient availability of the biomass fed. The lower the digestibility and degradability of the feed substrate, the lower the growth and protein accumulation of the larvae – and the higher the CO₂ emissions. As expected, larvae grow significantly better when fed with more nutrient-rich biomass. At the same time, increased ammonia emissions can occur under these conditions towards the end of the growth phase. These are probably related to an unbalanced protein-energy ratio in the feed substrate towards the end of the growth phase. However, the decisive factor is how these emissions are evaluated.
‘Emissions can only be meaningfully classified if they are related to the actual output – for example, the protein yield or the dry matter of the larvae,’ explains PD Dr Manfred Mielenz from the Nutritional Physiology working group at the FBN. ‘Higher absolute emissions do not necessarily mean a worse carbon footprint if the emissions per unit of high-quality protein produced are lower.’
However, a final assessment of emissions requires consideration of the entire life cycle. In addition to the rearing of the larvae, this also includes the production of feed substrates and the handling of residual materials at the end of the growth phase.
Initial guidance for the assessment of insect protein
The study not only provides important quantitative emission data, but also indicates how the nutrient content of feed substrates can be specifically optimised to reduce emissions and further improve the efficiency of insect production.
In an initial comparative analysis, CO₂ emissions related to protein production in black soldier fly larvae are below the values described in the literature for cattle and chickens. However, the authors expressly emphasise that this is an initial estimate and that further research is needed.
Against the backdrop of national climate targets, the German bioeconomy strategy and European farm-to-fork approaches, the study emphasises that new production systems require robust and comparable key figures. The present results provide initial scientific guidance in this regard, but do not replace comprehensive life cycle analyses. However, integrating insects into existing production systems can help to make the production of high-quality animal protein more sustainable in the long term.
The Research Institute for Farm Animal Biology will continue to advance insect research in the future in order to thoroughly evaluate the environmental impact of new protein sources and provide scientific support for their sustainable use.
PD Dr. rer. nat. habil. Manfred Mielenz
Research Institute for Farm Animal Biology (FBN)
Working Group Nutritional Physiology
Wilhelm-Stahl-Allee 2
18196 Dummerstorf
T: +49 38208 68-685
M: mielenz@fbn-dummerstorf.de
Manfred Mielenz, Thomas Geick, Solvig Görs, Gürbüz Daş, Dirk Dannenberger, Laura Gasco, Sara Bellezza Oddon, David Deruytter, Liane Hüther, Sven Dänicke, Cornelia C. Metges,
Energy and nutrient composition and origin of common feed substrates for black soldier fly larvae determine their efficiency and life-stage-specific carbon dioxide and ammonia production,
Bioresource Technology, Volume 443, 2026, 133812, ISSN 0960-8524, https://doi.org/10.1016/j.biortech.2025.133812.(https://www.sciencedirect.com/sc...)
Experimental setup: Larvae of the black soldier fly (Hermetia illucens) in a respiration chamber for ...
Copyright: FBN
Close-up of the black soldier fly (Hermetia illucens)
Copyright: Nordlicht/FBN
Criteria of this press release:
Journalists, Scientists and scholars, all interested persons
Biology, Environment / ecology, Nutrition / healthcare / nursing, Oceanology / climate, Zoology / agricultural and forest sciences
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English
Experimental setup: Larvae of the black soldier fly (Hermetia illucens) in a respiration chamber for ...
Copyright: FBN
Close-up of the black soldier fly (Hermetia illucens)
Copyright: Nordlicht/FBN
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