Effects of introducing Pseudomonas putida to black soldier fly (Hermetia illucens) Gainesville diet

With a growing human population, food security and waste management strategies are needed. To avoid food competition, insects have been promoted for both. Black soldier fly larvae (Hermetia illucens) are widely endorsed for their ability to decompose substrates and as feed. Recent studies show the life cycle and behavior of black soldier fly larvae can be impacted by bacterial supplementation. We determined effects of supplementing Gainesville diet of black soldier fly larvae with Pseudomonas putida, as this bacterial species can degrade recalcitrant compounds suggesting the possibility of making nutrients in larval diet more readily available. Further, this bacterium is heavily involved in nitrogen cycling, and could benefit black soldier fly organics upcycling for soil amendments. We conducted two bench-top studies, one with daily larval agitation, the other with only limited agitation. We measured larval mass, frass conversion, C:N content, and ammonia production with supplementation of P. putida in single and double-doses. Comparisons of data between both experimental designs showed that daily interruptions in the larval rearing system in P. putida treatment groups produced larger dried larval masses but the opposite is true when the system is left alone for the same amount of rearing time. Overall, data suggest that aeration is a positive driver for larval growth, and a lack of aeration, along with ammonia or other compounds in the P. putida treatment groups, could have impacted larval mass, measured energy, and frass to biomass conversion. an important consideration depending on the desired end product and utility.