Recycling of spent mushroom substrate and food waste: utilisation as feed materials for black soldier fly (Hermetia illucens (L.) Diptera: Stratiomyidae)

Abstract

Spent mushroom substrate (SMS) is the organic material remaining after harvesting mushrooms. We evaluated the potential of using SMSs of four different edible fungi (Auricularia heimuer, Lentinus edodes, Pleurotus eryngii and Pleurotus citrinopileatus) as a food resource for rearing black soldier fly (Hermetia illucens) larvae (BSFL) and to decrease waste recycling and save conventional feed. The larval weight after being fed only on the SMS of L. edodes (68.8 mg), a mushroom with worldwide cultivation, was heavier than larvae fed entirely on P. eryngii SMS (38.3 mg). The L. edodes SMS was selected from the various SMS treatments and subsequently mixed with food waste in different percentages to make BSFL rearing medium. When L. edodes SMS replaced 0, 10, 20, 30, 40, 50, 60, 70, 80 or 90% of the food waste in the mixed feed treatments, the BSFL survival rates (99.2-100%) did not differ among the treatments. Body size or weight was reduced only when 90% of the food waste was replaced by L. edodes SMS. A higher percentage of BSFL, however, developed into prepupae (55.8, 46.7, 75.8%, respectively) when 20, 30 or 90% of the food waste were replaced by L. edodes SMS. Compared to BSFL fed entirely on food waste, larvae fed a mixed diet consisting of 30% L. edodes SMS and 70% food waste had a lower fat content (178.1 g/kg) and a higher content of crude ash (15.54%), crude fibre (17.81%), crude protein (38.13%), and moisture (10.08%). Although the aerobic plate count (9,200 cfu/g), total mould count (260 cfu/g), and the arsenic (0.1830 mg/kg) and lead (0.202 mg/kg) contents increased in larvae reared on the mixed diet, all were below the safety limit. Collectively, these results suggest that mixed diets consisting of 20-30% L. edodes SMS and 70-80% food waste have a great potential as a daily medium for culturing this important resource insect.

Analysis of heavy metals in the conversion of lake sediment and restaurant waste by black soldier fly (Hermetia illucens)

“…The group of restaurant waste that contained no pure sediment demonstrated the lowest BSFL survival rate, while the group of restaurant waste that had meat sediment showed a higher BSFL survival rate (Figure 2). This corroborates the previous finding by Li et al (2021). Adding restaurant waste to the substrate for BSFL culture to improve the survival rate of BSFL is not a very rare occurrence and has been used before (Cai et al, 2019).…”

“…Both the average insect length and insect weight showed a remarkable difference in 100% restaurant waste and 1:4 groups than in other groups. Li et al (2021) concluded that adding 50% wheat bran, 30% alfalfa meal, and 20% corn meal resulted in an average insect length of 23.5 mm and an average insect weight of 240 mm, which were significantly different from those observed in the BSFL group fed with other pure mushroom wastes. According to Julita et al (2018), the proportion of organic waste, such as vegetables, should be increased in the substrate to improve the yield of BSFL.…”

A review on edible insects in China: Nutritional supply, environmental benefits, and potential applications

“…The black soldier fly-derived oil is a high-quality biodiesel with a high content of medium-chain saturated fatty acids of 67% (w%) and a low concentration of polyunsaturated fatty acids of 13%. The residual serves as green compost candidates for the growth of crops ( Jucker et al, 2020 ; Li et al, 2021 ; Ragossnig and Ragossnig, 2021 ; Surendra et al, 2016 ; Zhang et al, 2021 ). Similarly, the bioconversion of swine manure using house fly provided value-added animal foodstuff with 56.9% protein and 23.8% total fat as dry matter, preventing waste products in an intensive animal production system from threatening public health ( Wang et al, 2013 ).…”

Spent substrate from mushroom cultivation: exploitation potential toward various applications and value-added products

“…The potential of six SMS derived from Auricularia cornea , Auricularia heimuer , P. eryngii , P. ostreatus , Pleurotus citrinopileatus , and L. edodes was recently evaluated to rear black soldier fly ( Hermetia illucens ) and Tenebrio molitor larvae. L. edodes SMS was shown to be the most suitable to replace the insects' conventional feed [ 96 , 97 ]. Furthermore, when Protaetia brevitarsis larvae were grown on L. edodes or Auricularia auricula-judae SMS, a nutrient-rich organic fertilizer with low phytotoxicity and high humic acid content was produced [ 98 ].…”