Re ECF Project: 2013-06

Project Title: Value of Hermetia illucens (black soldier fly) for food waste conversion in Hong Kong

Applicant: Dr CHU Lee Man, of The Chinese University of Hong Kong

Total Approved Grant: $499,500 (ECF & WWGF: 50/50)

Duration: 1/9/2014 to 30/11/2015

Project Status/Remarks: Project completion to be reviewed by the ECF Research Projects Vetting Subcommittee

The present study examines the waste reduction capability of using Hermetia illucens ( black soldier fly ( BSF)) in recycling various common food wastes in Hong Kong. The project aims to -

  • assess the effect of different food substrates on the growth rate of BSF larvae based on the diet habit in Hong Kong;
  • characterize the conversion rate of various food waste mixes by BSF larvae;
  • evaluate the effect of seasonings and additives on waste conversion capability;
  • study the nutritive value of larval protein as fish feed; and
  • expand the scale so that a pilot conversion system can be evaluated for its usefulness and efficiency in food waste management.

Summary of the Findings/Outcomes:
The study examined the waste conversion capacity of black soldier fly (BSF) in recycling food wastes in Hong Kong. BSF larvae consumed different food substrates to various extents. For the genuine food waste study, waste collected from a hotel showed a comparable result with the commercial chicken feed; BSF larvae reared on other types of food waste like university canteen, restaurant from a mall as well as mixture of food wastes from these eateries showed relatively slow growth rate but reasonable food reduction rate and conversion rate, though the two outcome parameters were somewhat contrasting. Food waste that gave the best consumption (removal) rate did not necessarily support the highest efficiency regarding the conversion to insect biomass. Nevertheless, this study demonstrated the feasibility and efficiency of applying BSF larvae on food waste recycling. Waste type with the best result in previous study was chosen for a scale-up study to produce great number of BSF prepupae for feeding trials on fish. Prepupae with good nutritional value but relatively slow growth rate were harvested, which were further used for making fishmeal in the feeding trials. More BSF prepupae were needed than produced, which was indicative of slightly declined growth performance despite higher food conversion rate. Two feeding trials that included both marine and freshwater fish species were conducted. For the marine Orange-spotted grouper, growth performance decreased along with the higher inclusion of BSF prepupae while the final protein content of fish muscle was not significantly different among treatments. Too much fat and indigestible carbohydrate in prepupae mixed diets were considered as the most adverse factors. Similarly, for freshwater Jade perch, no differences were found among all parameters in all treatments. Prepupae mixed diet was as good as the commercial feed for fish growth. To conclude, BSF larvae were capable of removing food wastes and converting them to insect biomass that were potentially good fish feed, though the high lipid content in the diet, hence lipid content in the BSF prepupae, was a concern.