The Study On Efficient Conversion Of Refractory Organic Wastes Such As Algal Mud,Silkworm Sand And Chinese Medicine Residue By Hermetia Illucens Wuhan Strain

Black soldier fly(Hermetia illucens L.)is currently one of the most promising resource insects.It can convert organic waste,produce insect biomass and organic fertilizer,and has important development potential in alleviating global food shortage and solving environmental pollution problems of livestock and poultry.In nature,the larvae of this species feed mainly on organic wastes such as livestock feces and kitchen leftovers.Many articles have pointed out that the larvae of black soldier fly can efficiently deal with animal manure,kitchen waste and agricultural waste,etc.However,it is still unknown whether their larvae can efficiently transform difficult organic wastes such as algae mud,silkworm sand and Chinese medicine residue.Therefore,in this study we used black soldier fly(Hermetia illucens L.Wuhan strain)domesticated in our laboratory,and selected the optimal conversion formula for the larvae through reasonable combination of refractory organic wastes such as algae mud,silkworm sand and pharmaceutical residues with traditional organic wastes(bran,corn husk,etc.).The conversion efficiency of the larvae of black soldier fly was further improved by adding growth-promoting Bacillus subtilis strain BSF-Cl.The main results are as follows:1.Study on conversion of algal mud,silkworm sand and Chinese medicine residue by black soldier fly Wuhan strainThe toxic algal powder was transformed by black soldier fly Wuhan strain larvae for 10 days,the material reduction rate was 46.12%,the conversion rate was 13.44%,the mortality rate of larvae was 2.50%,and the degradation rate of algal toxin was40.98%.Only 0.81% of algal toxin was transferred into black soldier fly,and the transfer amount was small,which proved the feasibility of algal sludge conversion by black soldier fly.Then,two optimized formulas were obtained by transforming black soldier fly into diets with algal mud and different proportions of wheat bran or corn husk.In the black soldier fly diet,when fresh cyanobacteria mud: bran =3:1 and fresh cyanobacteria mud: corn husk: fungus residue = 4:2:1,the overall conversion efficiency of black soldier fly was the highest.When the addition of dry matter of algal mud in the feed of the larvae of black soldier fly is less than 10%,their growth will not be negatively affected,and a better conversion rate and higher material reduction rate can be obtained.However,a large number of black soldier fly died and the conversion time was prolonged when the addition of dry matter in algal mud exceeded 14%,which may be related to the amount of algal toxin in algal mud.In this study,two optimized formulas were obtained by transforming silkworm sand into feed with different proportions of corn husk and bran by the larvae of Wuhan black soldier fly.In the Wuhan black soldier fly feed formula,when fresh silkworm sand: corn husk = 1:1,the comprehensive conversion efficiency of black soldier fly was the highest,and the material reduction rate was 61.49% and the conversion rate was 16.31%.Fresh silkworm sand: bran = 1:1,the comprehensive conversion efficiency is the highest,the material reduction rate is 60.29%,the conversion rate is 14.81%.It was found that the larvae of Wuhan black soldier fly could transform the residue of traditional Chinese medicine,but the effect was not ideal,and the residue could be used as additive in Wuhan black soldier fly feed.2.Study on improving conversion efficiency of traditional Chinese medicine residue by combining black soldier fly Wuhan strain with growth-promoting bacteria(BSF-CL)In this study,Bacillus subtilis BSF-Cl was inoculated into black soldier fly system to transform traditional Chinese medicine residues,and the co-conversion of black soldier fly and B.Subtilis BSF-Cl improved the conversion efficiency and shortened the conversion time.The larval weight gain rate,conversion rate and material reduction rate were increased by 11.2%,11.7% and 8.3% respectively,and the conversion time was shortened by one day.These results suggest that BSF-Cl can improve the efficiency of black soldier fly using Chinese medicine residue ingredients and effectively promote the growth and development of the larvae,but the specific mechanism needs further experimental demonstration.In conclusion,this study found that the Wuhan black soldier fly has a certain degradation effect on the algal toxins in cyanobacterial mud.Hard-to-treat organic wastes such as algae mud,silkworm sand and traditional Chinese medicine residues can also be efficiently used by the larvae of Wuhan black soldier fly when properly combined with traditional organic wastes such as bran and corn husk.Finally,using growth-promoting bacterium BSF-Cl can further promote the growth of Wuhan black soldier fly and efficiently transform the residue.