Several insect species are mass produced for animal feeds, fish bait, or human consumption. The yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), is one of the more-popular insects considered for this use. To make T. molitor competitive with more-traditional protein sources, mass production must be optimized. Herein, we review the scientific literature on the range and optimal environmental, physical, and dietary conditions for the rearing T. molitor. Our review identified that: (a) the optimum temperature for T. molitor growth is 25–28°C; (b) T. molitor larval growth rate is greatest at ≥70% relative humidity (RH) with an optimum range between 60–75% RH, and; (c) optimal growth is achieved with diets containing 5–10% yeast, 80–85% carbohydrate, and the addition of B-complexvitamins.

Among the insect species reared as alternative protein sources, Hermetia illucens (black soldier Fly, BSF) has shown a huge potential mostly due to its high protein content, its bioconversion rates, and versatility in using different feeding substrates. Insect rearing may use continuous or batch feeding regimes and, among the used substrates, supermarket feedstock waste has gained recent interest under a circular economy perspective, but several uncertainties remain regarding the heterogeneity and the potential effects of the quantity and quality of these substrates on BSF larvae (BSFL) development. In this experimental work, five replicates of a hundred BSFL were fed in a continuous feeding regime, using seven different isolated vegetables as substrates (wheat bran, pumpkin, apple, grape pomace, red onion, red cabbage, and spinach), at three different temperatures (20, 25, and 30 °C) and two substrate moisture conditions (natural and 70% substrate moisture), until 50% of the larvae achieved the prepupal stage. BSFL performance and bioconversion parameters were evaluated. Our results show that some substrates should be avoided when rearing Hermetia illucens on feedstocks. Among these, apple feed led to poorer and slower development performances with more than 100 days of larval stage, while grape pomace and spinach showed higher mortality rates, which may be due to some anti-nutritional compounds. Larvae fed on pumpkin, red cabbage, and red onion presented good bioconversion results with higher values of efficiency of conversion of digested feed between 14.4 and 25. This work delivers relevant results for black soldier fly reared on a continuous feeding system using vegetable feedstock substrates and their potential trade-offs.

Hermetia illucens (Black Soldier Fly) larvae (BSFL) have great potential as new protein source for either feed or food use due to the high content of protein and fat. BSFL may be used in different forms including dried with extended shelf life. Mathematical models describing dehydration kinetics are useful to optimize BSFL drying conditions. A non-stationary 3D diffusion model, given by Fick's Law was used to describe the moisture depletion inside BSFL during drying. The numerical solution of PDE was obtained with COMSOL Multiphysics assuming simple boundary conditions. Data were obtained in a drying experiment performed with fresh larvae uniformly laid on a metallic grid in a forced air oven at 80 °C. Five randomly larvae were periodically selected and removed for moisture content determination until equilibrium moisture was reached. A qualitative good agreement between predictions and data was observed corroborating that the main physical phenomena were considered in the mathematical description. A better quantitave description is expected with the improvement of the boundary condition at larvae surface in the model and the upgrading of the three-dimensional geometry used as domain for the numerical resolution.

Insects are a new alternative for food and feed and a solution for circular economy. Among the most promising insects, black soldier fly, mainly in the larvae phase, is a solution specially for feed, and in particular in its dried form. The aim of this work was to study the water loss transfer during convective drying of black soldier fly larvae (BSFL). The mass transfer model consisted of mass diffusion with two alternative boundary conditions (no external resistance and convection) and with/without shrinkage, applied with finite elements method, with a triangular mesh of 3,036 elements and a geometry reproducing the shape of the larvae. The moisture diffusion coefficient, estimated from the experimental data assuming an infinite slab, increased from 0.7002×10^-10 m²/s at 60 °C to 2.792×10^-10 m²/s at 90 °C, with an activation energy of 43.97 kJ/mol. The simulation predicted with detail the water content profile showing a quick water loss on the outer layers of the BSFL at the initial times. The evolution of the overall water content of BSFL during drying was better predicted for long times (when more than 80% of the moisture was removed) and at the highest temperature of 90 °C and showed that diffusion was the dominating mechanism, with small influence of the boundary conditions studied. Although shrinkage between 21 and 29% was considered, depending on the temperature, the inclusion of volume change in the model did not significantly improved the water content prediction.

Purpose: Insect rearing for food and feed has gained momentum as an emerging sector aimed at addressing global food security and enhancing sustainability. However, several environmental studies raised concerns and questioned this growing industry, especially in the European context. This review aims to systematically summarize the current available knowledge on Life Cycle Assessments (LCA) in insect production systems, evaluate how different LCA methods and production configurations influence the environmental and sustainability outcomes and determine major trends and knowledge gaps, emphasizing what is sufficiently robust and what needs a critical re-examination. Methods: A systematic review of the available literature of peer-reviewed case studies that employed LCA methodology for insect mass was performed. Data were extracted on key methodological aspects: functional units (e.g., insect biomass, protein, fat, waste treated), system boundaries (e.g., cradle-to-gate, cradle-to-plate), allocation methods (economic, mass, system expansion), impact assessment methods (ReCiPe, TRACI, CML, IPCC), and data sources (primary and secondary databases such as Ecoinvent and Agri-footprint). The review also considered production scale, insect species, geographical distribution, and end-use purposes. A SWOT analysis was also performed to assess the internal strengths and weaknesses, and external opportunities and threats of LCA applications in insect farming, presenting implications for future research and policy. Results and discussions: Insects have several advantages over traditional livestock; nonetheless, comparability of LCA studies is challenged by methodological disparities, most notably in the way functional units, system boundaries, allocation procedures and impact assessment methods are defined. The strength of evidence is also restricted when considering data quality of direct emissions, energy consumption, water use, and nutritional content. Consequential LCA is still scarcely used, though it can help to capture market dynamics and system-wide consequences. Feed category, energy carriers, and technological processing exert influences on environmental performance, with waste-based feeding and replacement fossil energy with renewable energy sources as recognized sustainable options. Proximity of insect farms with related industry sectors, that produce adequate feedstock, while reducing feeding stuff transportation costs, can increase sustainability. Conclusions: Although insect farming is considered a potential and sustainable option for future food systems, its utmost potential can be reached only through consistent knowledge, data precision improvements and more widespread use of consequential approaches, being LCA an important tool to achieve the sustainability goals. The development of consistent tools to evaluate sustainability trade-offs, increase the regulations flexibility, and build markets, is critical to place insect farming as a viable, and resilient component of innovative food systems.