Growth of Hermetia illucens on waste from mass rearing of other insect species

Recent interest in integrating insects into the human food chain, as a sustainable protein source for both food and animal feed, has led to a growing number of insect farms establishing across Europe. Cricket and grasshopper species are suitable for human food applications and, despite their higher production efficiency than traditional livestock, their farming still produces substantial quantities of organic waste; consisting of frass, exuviae and uneaten food. Here we assessed the potential use of Hermetia illucens (Dipetra: Stratiomyidae), the black soldier fly (BSF), as a bioaccumulator to recapture the nutrients from this waste for potential applications in the animal feed, pet food, biofuel or pharmaceutical industries. BSF larvae were reared on three experimental diets: (1) cricket farm waste; (2) locust farm waste; and (3) the Gainesville diet, used as a control. Farm wastes were used either unmodified or finely chopped giving five experimental conditions. Trials were started with young handling larvae, provided feed ad libitum and reared in a climate chamber. The impact of experimental condition on BSF mortality, developmental time, final larval mass, and adult emergence was assessed. Adult flies were successfully reared on all diets, demonstrating their suitability for BSF growth. The final weight of larvae reared on cricket waste was significantly higher than those on the locust and control diet. Chopping the locust waste did not affect larval weight. Diet did not significantly affect time taken to reach the prepupal stage, but chopping the locust waste diet significantly slowed the developmental rate. Mortality rate was low and not significantly affected by diet. We conclude that among substrates suitable for rearing H. illucens, the waste from farming locusts and crickets represents another opportunity for this interesting saprophagous species. The bioconversion ability of H. illucens means that wastes from the edible insect industry represent a new feed source for the mass rearing of this species, providing the opportunity to establish a circular nutrient econom