BACKGROUND AND OBJECTIVES: Organic waste accumulation demands sustainable valorization strategies. Black soldier fly larvae efficiently convert waste into chitin-derived chitosan, an eco-friendly biostimulant. However, comparative efficacy of insect versus crustacean chitosan in
orchid acclimatization remains unexplored. The objectives of this study were to evaluate effects of chitosan from fish scales, shrimp shells, and black soldier fly larvae exuviae at ۰, ۵, ۱۰, and ۱۵ milligrams per liter on growth of four epiphytic orchids (Coelogyne asperata, Coelogyne pandurata, Dendrobium species., Grammatophyllum speciosum) over ۱۲ weeks, while characterizing structural differences using Fourier Transmission Infrared spectroscopy.METHODS: A completely randomized factorial design with five replicates per treatment was employed. The black soldier fly larvae exuviae chitosan was extracted via demineralization, deproteinization, and deacetylation (۷۰ percent deacetylation), while commercial fish and shrimp chitosan showed ۹۵ and ۸۰ percent. Plantlets were cultured on Murashige and Skoog medium supplemented with chitosan treatments. Plant height, leaf, root, and shoot numbers were recorded weekly. Two-way Analysis of Varian was performed.FINDINGS: The Fourier Transmission Infrared spectroscopy confirmed characteristic chitosan peaks across sources. Shrimp chitosan exhibited a pronounced Nitrogen-Hydrogen bending vibration at ۶۸۵.۴۵ centimeters to the power of minus one, while black soldier fly larvae exuviae chitosan displayed a unique skeletal vibration at ۶۶۰.۷۰ centimeters to the power of minus one.
Chitosan source and concentration did not significantly affect plant height, root number, or shoot number across all species. However, leaf number showed species-specific responses. In Coelogyne asperata, shrimp chitosan at ۱۰ miligram per liter produced ۶.۸ leaves versus ۴.۲ in controls (۶۲ percent increase). The Grammatophyllum speciosum treated with shrimp chitosan at ۵ miligram per liter yielded ۵.۵ leaves versus ۳.۸ in controls.
Chitosan source and concentration did not significantly affect plant height, root number, or shoot number across all species. However, leaf number showed species‑specific responses.CONCLUSION: The black soldier fly larvae exuviae chitosan serves as a sustainable alternative to crustacean chitosans for
orchid acclimatization. Leaf proliferation can be enhanced in a species- and source-dependent manner, supporting circular economy principles and guiding tailored biostimulant formulations for
orchid conservation.