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Securing protein for the approximate 10 billion humans expected to inhabit our planet by 2050 is a major priority for the global community. Evidence has accrued over the past 30 years that strongly supports and justifies the sustainable use of insects as a means to produce protein products as feed for pets, livestock, poultry, and aquacultured species. Researchers and entrepreneurs affiliated with universities and industries, respectively, from 18 nations distributed across North and South America, Europe, Asia, Africa and Australia contributed to the development of this article, which is an indication of the global interest on this topic. A brief overview of insects as feed for the aquaculture industry along with a review of the black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), as a model for such systems is provided.

The feed sector requires new sustainable sources of protein, and at the same time better waste management practices are required to decrease and upcycle post-consumers’ food waste (catering and organic household waste), which is currently used for energy production or discharged as waste. The production of Hermetia illucens larvae (L.) (BSFL) was conducted in 15 batches at pilot scale. Furthermore, a feeding strategy experiment was conducted to optimize feedings and decrease handling, followed by a digestibility study for assessing the applicability of BSFL as a feed ingredient. About 190 kg of food waste was used to produce 79 kg of BSFL. The bioconversion of food waste into BSFL was found to be highly efficient, with feed conversion rate (FCR) values ranging between 1.7 and 3.6, when assessed on dry matter. The feeding experiment showed similar BSFL and insect frass production as well as similar FCR, revealing that a decrease in handling can be obtained if two feeding episodes are used. The digestibility of protein and fat was high at 86.2 and 90.4% and revealed that BSFL meal can be successfully used as a protein and fat source in feed for carnivore animals outside the food chain (e.g., pet food).

A major barrier for using animal waste as substrate for production of insects for feed or food is the concern for safety of the end products. In this study we investigated how rearing of fly larvae of Musca domestica in poultry manure influenced the counts of three pathogenic test strains (Escherichia coli, Salmonella Enteritidis and Campylobacter jejuni) and investigated whether these were transferred from manure to larvae, pupae or adults flies. We monitored quantitative microbiological changes over a study period of seven days. We showed that the decay in the numbers of E. coli, S. Enteritidis, and C. jejuni was faster in manure with rearing of fly larvae than in manure without larvae; an 8 log10 reduction of all three test bacteria was observed within four days in manure with larvae; compared to manure without larvae where a 1 to 2 log10 was observed. We found no sign of propagation of the pathogens in the larvae gut. All test strains were detectable in low numbers at day 4 in the larvae gut but only C. jejuni survived until day 7. In the pupae, only S. Enteritidis was detectable at day 3, and no test strains were found later than day 3. None of the test strain was isolated from adult flies. The total aerobic bacterial count remained at a high level throughout the study both in manure, in larvae and in pupae. In conclusion, our results showed that elimination of the pathogens from the manure was accelerated by larvae rearing, but were still detectable at low number in the larvae gut until end of the larvae stage. This study provides data for evaluation of feed safety of fly larvae reared on animal waste. Furthermore suggests a potential use for reduction of these pathogens in manure.

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