Bioconversion potential of tomato, corn, and date palm wastes by black soldier fly larvae: a comparative evaluation

Black soldier fly larvae (Hermetia illucens L.; BSFL) are increasingly used for organic waste valorization; however, the suitability of 100% non-food agricultural residues common in arid and semi-arid systems remains insufficiently tested without supplementation. This study compared growth performance, bioconversion efficiency, and nutrient outputs of BSFL reared for 14 d on chicken feed (control) versus 100% corn, tomato, and date palm wastes. Larvae were reared under controlled conditions in a completely randomized design (n = 3 per treatment). Growth, substrate reduction, bioconversion efficiency, larval composition, and frass properties were measured. Data were analyzed using 1-way analysis of variance with Tukey's honest significant difference (HSD) (α = 0.05). Chicken feed produced the highest final larval weight (0.166 ± 0.010 g), while corn waste supported intermediate growth (0.070 ± 0.004 g). Tomato and date palm wastes resulted in minimal final weights (0.011 ± 0.001 g and 0.014 ± 0.002 g), indicating failure to support development when used alone. Substrate reduction and bioconversion efficiency were highest in the control, intermediate in corn waste, and lowest in date palm waste. Larval protein content was highest in chicken feed and tomato waste, intermediate in corn waste, and lowest in date palm waste. Tomato-derived frass showed elevated electrical conductivity and chloride, suggesting salinity risk limiting direct soil application without dilution. Corn waste showed the greatest potential for BSFL bioconversion without supplementation. Tomato and date palm wastes in pure form were unsuitable and likely require pretreatment and/or co-substrates to enable larval growth and safer frass use.