Supplementing aquaponics with black soldier fly (Hermetia illucens) larvae frass tea: Effects on the production and composition of sweetpotato slips and sweet banana peppers

Abstract

In this 10-week study, sweet banana chili plants (Capsicum annuum) and sweetpotato (Ipomea batatas) slips were cultured with or without media and with or without black soldier fly (Hermetia illucens) larvae (BSFL) frass tea supplementations in a 2 × 2 factorial design. Each treatment was triplicated with 30 channel catfish (Ictalurus punctatus) juveniles and plant growth was periodically monitored and harvested. Water quality and minerals were measured throughout the study and at final sampling, the mineral/phenol/antioxidant capacity was measured in the sweetpotato leaves, sugar content was measured in the sweet chilies and final sizes/survival of catfish were recorded. BSFL frass tea additions had no significant effect on water quality. Such additions also had no adverse effect on catfish growth, feeding efficiency or liver histology. However, BSFL frass tea significantly elevated water calcium, potassium and phosphorus levels at weeks 1, 5 and 10 while magnesium was significantly higher on weeks 5 and 10. BSFL frass tea significantly elevated manganese in sweetpotato leaves, but no increase in production, possibly due to BSFL frass having no effect on water iron levels that were undetectable throughout the study. Similarly, BSFL frass tea had no effect on chili production but did significantly elevate total sugar content. Sweetpotato slip and chili production were significantly increased in media and without media, respectively. Overall, results show that leafy growth was significantly better with media, fruiting was significantly better without media, and BSFL frass tea enhanced the nutritional quality of the aquaponic products without compromising fish production or water quality.