New publication: Klammsteiner et al. (2025) iScience 28(7), 112794

Study summary:
In this study, we investigated how varying larval densities influence thermogenesis in black soldier fly larvae (BSFL) reared on food waste, and assessed the potential of potassium sorbate as an agent to reduce heat generation. By monitoring temperature changes within the substrate, we observed that larval density significantly drives thermogenesis, with higher densities leading to increased heat production. The presence of potassium sorbate, however, was associated with reduced larval biomass gain and slower waste degradation, which in turn impacted the extent of thermogenesis observed. Additionally, we found that the supplementation of potassium sorbate altered the physicochemical properties of the substrate and shifted the composition of both gut and frass microbiomes. These findings highlight the interconnected effects of preservative residues on larval metabolism, heat generation, and microbial dynamics in BSFL-based food waste bioconversion systems.

Link to full study: doi.org/10.1016/j.isci.2025.112794

**Graphical abstract.** An overview of the key outputs from the black soldier fly bioconversion process, accompanied by an illustration of how increasing larval densities influence substrate temperature profiles. The addition of potassium sorbate not only delays and reduces peak temperatures but also impacts larval development.

Additional information:
We have also created a website that provides comprehensive data download options and detailed documentation. The website is linked in the publication and can be accessed at: tklammsteiner.github.io/templarvae.

**Figure 1.** A preview of the website providing additional information on the data and analysis.

References

2025

Larval density drives thermogenesis and affects microbiota and substrate properties in black soldier fly trials

Thomas Klammsteiner, Carina D. Heussler, Heribert Insam, Birgit C. Schlick-Steiner, and Florian M. Steiner

iScience, May 2025

Abstract doi Bib PDF

Industrial insect farming has potential for converting low-value organic waste into nutrient-rich insect biomass, producing valuable by-products like organic fertilizers. However, a better understanding of density-related thermogenesis and microbial dynamics is needed to enhance standardization and bridge gaps between laboratory and industry needs. This lab-scale study focuses on the black soldier fly (Hermetia illucens), which exhibits thermogenesis that intensifies with larval population size and its natural crowding behavior. Using high-resolution temperature monitoring and biomolecular methods, we found that doubling larval density (0, 1.25, 2.5, 5 larvae/cm2) increased temperatures by 0.6 to 2.4 °C, depending on the treatment. Adding potassium sorbate altered microbial profiles, increasing Enterobacter and decreasing Providencia, while promoting lactic acid bacteria. Density also impacted pH, water content, dry matter, volatile solids, and ash in the substrate. Our findings provide essential insights into managing microbial and thermal dynamics, offering valuable information for optimizing and standardizing conditions in rearing trials.
@article{klammsteiner_iscience_2025, title = {Larval density drives thermogenesis and affects microbiota and substrate properties in black soldier fly trials}, issn = {2589-0042}, url = {https://www.sciencedirect.com/science/article/pii/S2589004225010557}, doi = {10.1016/j.isci.2025.112794}, urldate = {2025-06-02}, year = {2025}, month = may, journal = {iScience}, volume = {28}, number = {7}, pages = {112794}, language = {eng}, author = {Klammsteiner, Thomas and Heussler, Carina D. and Insam, Heribert and Schlick-Steiner, Birgit C. and Steiner, Florian M.}, keywords = {circular economy, composting, thermal ecology, preservation, microbiome, food waste, heat}, dimensions = true, }