Evaluation of the nutritional value and functional potential of several meal fractions produced from black soldier fly (Hermetia illucens) larvae in rainbow trout (Oncorhynchus mykiss) feed

The aquaculture sector has been growing since the 1950s to meet the increasing demand of the consumer market. The development of this sector also leads to a strong demand for raw material to feed fish farms. Fishmeal is currently used on a massive scale because it has characteristics adapted to the nutritional needs of fish. They are made from forage species from industrial fisheries or from by-catches. This is one of the major problems of this sector, which is currently neither sustainable nor ecological. It is therefore necessary to develop alternative sources of animal protein to replace fishmeal. Since July 2017, the use of seven species of insects in aquaculture feed has been authorised. This is particularly the case for Hermetia illucens, a species capable of efficiently converting a wide variety of organic matter into biomass, particularly plant organic matter.

It is in this context that this CIFRE thesis project was born, with the framework of a tripartite collaboration bringing together an industrial partner, the company Innovafeed, created in 2016, which is one of the leaders on the market for the production of insect meal from the species Hermetia illucens a UMR specialising in the nutrition and metabolism of farmed fish (UMR 1419 NuMéA, INRAE) and the PhyPAQ team of UMR BOREA developing "omics" approaches on teleost fish and cephalopods.

The objective of this thesis is to evaluate the nutritional value and functional potential of several meal fractions produced from black soldier fly (Hermetia illucens) larvae, with a view to rapidly obtaining direct applications in fish farming. The model fish species chosen for this study will be the rainbow trout (Oncorhynchus mykiss), which, with more than 35,000 tonnes produced annually, is the leading fish species raised in France.

Organisation of the research work:

• Stage 1 : characterise the insect meal using transcriptomic/proteomic/peptidomic and biochemical omics approaches
• Step 2 : Identify bioactive peptides by coupling separation techniques (rpHPLC) with in vitro myotropic and antibacterial functional tests (bioassays).
• Step 3 : evaluate the nutritional value of meal fractions: digestibility measurement, growth test (body composition, histology of intestinal villi, expression profile of certain intestinal genes (RNAseq), composition of the intestinal microbiota (metabarcoding), determination of the myotropic potential of feeds, evaluation of feed palatability (behavioural approach, DanioVision and EthoVision XT Noldus)