Storing live black soldier fly larvae: the influence of temperature and storage techniques

The use of live larvae of Hermetia illucens for farmed animals has shown positive influence on their behaviour, welfare and health. However, insect rearing facilities may not be in the immediate proximity of the farm that will receive the live larvae. Storage and transport at low temperatures could be then necessary to preserve the larvae until consumption. The aim of this study is to evaluate the feasibility of storing live larvae at cold temperature with different storage methods. Tested treatments (5 replicates each) were: quantity (1 kg or 3 kg), type of container (bucket or bag), the addition (or not) of frass and storage temperature (6 °C, 8 °C and 10 °C). Larvae samples were daily taken from each replicate, live and dead larvae were counted, and the weight of the live larvae was recorded. A replicate was considered over when 15% of the larvae were dead. Data were analysed by means of generalized linear mixed models ([GLMM] IBM SPSS software, P ≤ 0.05). Storing black soldier fly larvae is possible in all the tested conditions, with losses below 15% and for periods below 6 days. The temperature plays a major role, with 10°C allowing the longest lifespan (P < 0.001). The addition of frass, storing larger quantities of larvae and using polypropylene bags were the treatments which enhanced larval lifespan (P < 0.001), while the use of bags instead of buckets reduced mortality (P < 0.01). The trade-off for longer storage of the larvae is a higher weight loss.