Greenhouse gases and ammonia emissions from the breeding of black soldier fly (Hermetia illucens L.) larvae

There is an increased interest in using insect larvae to recycle organic waste in high-quality protein products for livestock and aquaculture feeds. Different species can be used for this propose and Hermetia illuncens L., the black soldier fly (BSF), is one of the most promising. However, during rearing, due to the metabolism of these insects and their excreted material, greenhouse gases (GHG) and ammonia (NH3) can be produced and emitted. A study has been carried out to investigate carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and NH3 emissions during rearing of BSF larvae. The diet tested were based on agro-industrial by-products: corn stover (CS), residues from vegetable processing (VW) and brewery waste (BW). Three diet were formulated: a cereal-based diet (Gainesville) used as control (C), C+25%CS and BW+25%CS. Black soldier fly larvae (BSFL) were housed in containers (5 replications per treatment) placed in a climate-controlled room. Air flow rate and temperature were set according to rearing conditions used by commercial BSFL rearing farms. Gaseous emissions were determined with dynamic chamber method by Infrared Photoacoustic Detection. BSFL rearing was shown to produce sizeable NH3 and GHG emissions. Estimated NH3 losses ranged from 2.15 mg (C) and 8.52 mg (BW) per gram of produced insect crude protein (CP), whereas cumulative GHG emissions averaged 2.68 gCO2eq/gCP. A full evaluation of BSFL meal production system, including GHG related to energy used for BSFL rearing and processing as well as to the management of rearing residues, is already under study by our research group.