Environmental impact of insect rearing for food and feed: state of the art and perspectives

The demand for feed and animal food products is expected to rise sharply until 2050. In addition, livestock production plays a role in the overall anthropogenic impact. Thus, valuable protein alternatives such as edible insects are welcome. Edible insects have an excellent protein value, low feed conversion ratio (FCR) and can be massively reared on low-value substrates. Based on the available literature, this paper is aimed at reviewing the environmental performances of insect rearing and drawing the perspectives for future investigations. To date, few papers focused on the environmental impact of insects farming and used the Life Cycle Assessment (LCA) as standardized methodology. Impacts such as Global Warming Potential (GWP), energy use (EU) and land use (LU) have been estimated for the mealworm meal (MM) production. If compared to some animal food products, the GWP of MM ranges from about a half (pork) to less than a tenth (beef) (Tab. 1), mainly due to the weak climate-relevant emissions of this insect. In addition, the low LU of MM production sounds promising and may be partially explained by the low FCR (2.2) observed for this species. With the exception of beef and pork, the EU of MM is higher than the literature values for the other animal food products due to the rearing facility climate-conditioning. For feed production, housefly larvae grown on organic wastes (including poultry manure) have been studied. The data were obtained from a commercial-exploited testing site. If compared to literature data on fishmeal (FM), housefly larvae meal (HLM) exhibits a very low impact on climate changes, but is comparable to soybean meal (SBM) production (Table 1). Producing HLM requires less agricultural land than SBM as no dedicated crops are required. The energy demand of HLM production is more than twice the EU for SBM meal, but it is lower than for FM. Even if comparisons between these studies are not easy due to several methodological aspects, edible insects appear more sustainable than other animal products or feedstuffs. However, other environmental indicators (e.g., acidification potential) should be investigated to get a complete understanding of the environmental performance of edible insects as food and feed. The different rearing strategies adopted have a significant effect on the sustainability of the mealworm and housefly rearing cycles. Studies comparing different insect species and/or different rearing strategies should be undertaken.