A method for promoting the stepwise conversion of straw by tenebrio and hermetia to produce high-protein insect bodies

Abstract

The application discloses a method for promoting yellow mealworm and black soldier fly to realize step-by-step conversion of straw to obtain high-protein worm bodies, which comprises the following steps: pre-fermenting straw by using intestinal microorganisms of yellow mealworm, feeding yellow mealworm by using the obtained pre-fermented straw to obtain worm bodies and straw worm manure, fermenting the straw worm manure by using intestinal microorganisms of black soldier fly and Penicillium janthinellum PA01, and finally feeding black soldier fly by using the obtained fermentation product. The intestinal microorganisms of yellow mealworm are enriched and cultured, the pre-fermentation of straw by using the intestinal microorganisms is used to improve the chewability and degradability of straw, and the efficiency of feeding yellow mealworm by using straw is improved. Then, the intestinal microorganisms of black soldier fly and Penicillium janthinellum PA01 are enriched and cultured, the straw worm manure is fermented by using the intestinal microorganisms of black soldier fly and Penicillium janthinellum PA01, the efficiency of feeding black soldier fly by using straw worm manure is improved, the step-by-step conversion of straw by using yellow mealworm and black soldier fly is realized, high-protein worm bodies and worm manure are obtained, the green conversion and cyclic utilization of straw are realized, and a new way for high-value application of straw is provided.

Description

Technical Field

[0001] This invention belongs to the field of high-value utilization technology of plant straw, specifically involving a method for promoting the cascade conversion of straw into high-protein insect bodies by yellow mealworms and black soldier flies. Background Technology

[0002] Yellow mealworms and black soldier flies are high-protein insects that are easy to raise and have high economic value. They have the ability to transform organic waste such as kitchen waste and livestock manure, and have been widely studied at home and abroad.

[0003] Straw is a byproduct of agricultural production. my country's annual crop straw production exceeds 800 million tons, accounting for about 20% of global straw resources, making it the world's largest straw producer. With the significant increase in my country's crop straw production, adjustments to rural energy structures, and regulations prohibiting straw burning, a large surplus of straw has emerged. How to efficiently and coordinately utilize straw resources is an important research topic.

[0004] Straw contains abundant organic matter, nitrogen, phosphorus, potassium, and trace elements, making it a potential biomass resource for feeding mealworms and black soldier flies. However, there are currently some problems with the conversion and utilization of straw for mealworms and black soldier flies: First, mealworms and black soldier flies have chewing mouthparts, and the hardness of straw makes it difficult for them to directly consume; second, insects like mealworms have short and straight digestive tracts, requiring feed with high nutritional content, and the dense structure of straw is not conducive to the conversion of cellulose and hemicellulose, and it is relatively lacking in nitrogen, so directly using it to feed mealworms and black soldier flies cannot meet their breeding needs. Currently, researchers generally use straw as a supplementary feed for insects, with a low proportion of straw in the feed, and the conversion efficiency of using straw as the main raw material for feeding mealworms and black soldier flies is low. Summary of the Invention

[0005] In view of this, the present invention aims to develop a method for efficiently converting straw using mealworms and black soldier flies to obtain high-protein insect bodies, so as to achieve the green conversion and recycling of straw.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw includes the following steps:

[0008] S1. Pre-fermenting straw with intestinal microorganisms of mealworms, wherein the intestinal microorganisms of mealworms include bacteria and fungi derived from the intestines of mealworms;

[0009] S2. Use the pre-fermented straw obtained in step S1 to feed mealworms and obtain straw worm excrement;

[0010] S3. Ferment straw and insect excrement by mixing black soldier fly intestinal microorganisms and Penicillium micropurus PA01. The preservation number of Penicillium micropurus PA01 is CCTCC NO: M2015757. The black soldier fly intestinal microorganisms include bacteria and fungi derived from the black soldier fly intestine.

[0011] S4. Use the fermentation product obtained from S3 to feed black soldier flies.

[0012] In the method of the present invention, the straw includes, but is not limited to, corn straw, rapeseed straw, rice straw, wheat straw and water hyacinth straw, and the straw can be one type of straw or a mixture of multiple types of straw in any proportion.

[0013] Preferably, in the above method, the length of the straw after mechanical crushing is <5cm.

[0014] Preferably, in the above method, the intestinal microorganisms of mealworms or black soldier flies are prepared by the following process: taking the intestines of mealworms or black soldier flies and placing them in physiological saline, grinding them into a homogenate, taking the homogenate and inoculating it into LB medium to obtain a bacterial suspension of mealworms or black soldier flies, taking another homogenate and inoculating it into PDB medium to obtain a fungal suspension of mealworms or black soldier flies, and mixing the corresponding bacterial suspension and fungal suspension to obtain the final product.

[0015] In some embodiments of the present invention, the preparation method of the intestinal microorganisms of yellow mealworms is as follows: yellow mealworms are taken, their surfaces are disinfected with alcohol, washed, and their intestines are dissected and placed in physiological saline. The intestines are then ground into a homogenate. The homogenate is diluted with sterile water, and a portion of the diluted homogenate is placed in LB liquid medium (containing 10 g / L peptone, 5 g / L yeast extract, and 10 g / L sodium chloride, with a pH of 7.0–7.2). Another portion of the diluted homogenate is placed in PDB liquid medium (each 1 L contains 200 g of filtrate obtained from boiling peeled potatoes and 20 g of glucose). The medium is then cultured in an air shaker at 30°C and 180 rpm for 72–96 h to obtain enriched bacterial and fungal cultures of yellow mealworms. The bacterial and fungal cultures are then mixed in equal proportions to obtain the intestinal microbial culture of yellow mealworms.

[0016] In some embodiments of the present invention, the preparation method of black soldier fly intestinal microorganisms is as follows: black soldier flies are taken, their surfaces are disinfected with alcohol, washed, and their intestines are dissected and placed in physiological saline. The intestines are then ground into a homogenate. The homogenate is diluted with sterile water, and a portion of the diluted homogenate is placed in LB liquid medium (containing 10 g / L peptone, 5 g / L yeast extract, and 10 g / L sodium chloride, with a pH of 7.0–7.2). Another portion of the diluted homogenate is placed in PDB liquid medium (each 1 L contains 200 g of filtrate obtained from boiling peeled potatoes and 20 g of glucose). The medium is then cultured in an air shaker at 30°C and 180 rpm for 72–96 h to obtain enriched cultured black soldier fly intestinal bacterial and fungal cultures. The bacterial and fungal cultures are then mixed in equal proportions to obtain the black soldier fly intestinal microbial culture.

[0017] Preferably, in the above method, the pre-fermentation conditions in step S1 are as follows: the moisture content of the straw is adjusted to 70-75%, the intestinal microorganisms of mealworms are inoculated and mixed, and the mixture is anaerobic fermented at 30-35°C for 7-9 days.

[0018] Preferably, in the above method, the rearing conditions in step S2 are as follows: insect density of 10-15 insects / g-straw, straw thickness of 1.5-2.5cm, temperature of 27±2℃, humidity of 65±5%, rearing for 40-60 days, and feeding the mealworm larvae with carrots or green vegetable leaves every 3 days to supplement their water.

[0019] More preferably, in the above method, the mealworms mentioned in step S2 are mealworm larvae fed with wheat bran, with an age of 60-80 days, a body length of 1.5-2.5 cm, and an individual weight of 0.06-0.08 g.

[0020] Preferably, in the above method, *Penicillium micropurpurum* PA01 is cultured through the following process: 2 mL of bacterial culture is inoculated into PDA liquid culture medium, and the culture medium is placed in an air shaker at 30°C and 180 rpm for 72–96 h to obtain *Penicillium micropurpurum* PA01 bacterial culture.

[0021] Preferably, in the above method, the pre-fermentation conditions in step S3 are as follows: the moisture content of straw and insect excrement is adjusted to 75-80%, black soldier fly intestinal microorganisms and Penicillium micropurus PA01 are inoculated and mixed, and then anaerobic fermented at 30-35°C for 6-8 days.

[0022] Preferably, in the above method, the rearing conditions in step S4 are as follows: the insect density is 5-7 insects / g-insect excrement, the straw-insect excrement thickness is 2.0-3.0cm, and the black soldier flies are reared for 12-15 days at a temperature of 30±2℃ and a humidity of 75±5%.

[0023] More preferably, in the above method, the black soldier fly larvae in step S4 are black soldier fly larvae fed with soybean meal, with an age of 4-6 days, a body length of 0.5-1.0 cm, and an individual weight of 0.013-0.017 g.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) This invention enriches and cultivates the intestinal microorganisms of yellow mealworms, and uses the intestinal microorganisms to pre-ferment change the structural characteristics of straw, thereby improving the chewability and degradability of straw and increasing the efficiency of feeding yellow mealworms with straw; then, the intestinal microorganisms of black soldier fly and the micropurus purpureus PA01 are mixed and fermented to improve the efficiency of feeding black soldier fly with straw and insect excrement.

[0026] (2) By pre-fermenting straw and insect excrement by intestinal microorganisms of yellow mealworms and black soldier flies, not only is the biodegradability of the substrate improved, but the abundance of straw-degrading bacteria in the intestine is also increased, which promotes the stepwise transformation of straw by yellow mealworms and black soldier flies, overcomes the problem of low efficiency in feeding yellow mealworms and black soldier flies with straw, and realizes the efficient green bioconversion of straw.

[0027] (3) Using the method of the present invention, high-protein insect bodies and insect excrement can be obtained at low cost. The insect bodies can be used as protein feed for pigs, fish and chickens or as raw materials for high-value nutritional products. The insect excrement can be used to make high-quality organic fertilizer, realizing the green transformation and recycling of straw and promoting the integration of planting and breeding. Attached Figure Description

[0028] Figure 1 The present invention provides a process flow diagram of a method for promoting the cascade conversion of straw into high-protein insect bodies by yellow mealworms and black soldier flies.

[0029] Figure 2 This is a comparison chart showing the growth rate of mealworm and black soldier fly body weight during the tiered conversion of corn straw under different treatment conditions in this embodiment of the invention. Detailed Implementation

[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terms “comprising” and “having”, and any variations thereof, used in the specification and claims of this invention, are intended to cover non-exclusive inclusion.

[0032] The efficient and coordinated utilization of abundant surplus straw resources is an urgent problem to be solved. However, in the feed of mealworms and black soldier flies, straw can only be added as an auxiliary ingredient and its proportion is low. To address this technical problem, this invention provides a method for promoting the tiered conversion of straw into high-protein insect bodies in mealworms and black soldier flies. This method can obtain high-protein insect bodies and insect excrement using straw as the main raw material. The insect bodies can be used as protein feed for pigs, fish, and chickens or as raw materials for high-value nutritional products, while the insect excrement can be used to make high-quality organic fertilizer. This achieves the green conversion and recycling of straw and promotes the integration of crop farming and animal husbandry.

[0033] For ease of explanation, the following description uses methods from some embodiments of the present invention as examples.

[0034] Please refer to Figure 1 , Figure 1 This is a process flow diagram of a method for promoting the cascade conversion of straw into high-protein insect bodies by yellow mealworms and black soldier flies, as described in some embodiments of the present invention. The method includes the following steps:

[0035] (1) Enrichment of intestinal microorganisms of yellow mealworms, wherein the intestinal microorganisms of yellow mealworms are derived from the intestines of yellow mealworms and include bacteria and fungi, wherein bacteria are enriched by LB medium and fungi are enriched by PDA medium;

[0036] (2) Using the intestinal microorganisms of yellow mealworms to pre-ferment straw, the pre-fermentation conditions are preferably: adjusting the straw moisture content to 70% to 75% and anaerobic fermenting the straw at 30℃ to 35℃ for 7 to 9 days;

[0037] (3) Feeding mealworms with pre-fermented straw using intestinal microorganisms of mealworms to obtain mealworms and straw excrement. The preferred feeding conditions are: a mealworm density of 10-15 mealworms / g-straw, a straw thickness of 1.5-2.5cm, feeding mealworms at a temperature of 27±2℃ and a humidity of 65±5% for 40-60 days, with timely water replenishment; the preferred mealworms are: 60-80 days old, 1.5-2.5cm in length, and 0.06-0.08g in weight per mealworm.

[0038] (4) Enrichment culture of black soldier fly gut microbiota, wherein the black soldier fly gut microbiota is derived from the black soldier fly gut and includes bacteria and fungi, wherein bacteria are enriched by LB medium and fungi are enriched by PDA medium;

[0039] (5) The culture of Penicillium micropurpurum PA01 can be activated and expanded using PDA liquid culture medium.

[0040] (6) The straw insect manure is fermented by mixing black soldier fly intestinal microorganisms and micropurus purpureus PA01 to obtain mixed fermented straw insect manure. The preferred fermentation conditions are: adjusting the moisture content of the straw insect manure to 75% to 80%, inoculating it with black soldier fly intestinal microorganisms and micropurus purpureus PA01, and then anaerobic fermenting it at 30℃ to 35℃ for 6 to 8 days.

[0041] (7) Black soldier fly larvae were fed with mixed fermented straw and insect excrement. After the feeding was completed, the black soldier flies and the remaining insect excrement were collected separately. The preferred feeding conditions were: larvae density of 5-7 larvae / g-insect excrement, straw and insect excrement thickness of 2.0-3.0cm, and black soldier flies were fed for 12-15 days at a temperature of 30±2℃ and a humidity of 75±5%. The preferred black soldier fly larvae were: larvae age of 4-6 days, body length of 0.5-1.0cm, and individual larvae weight of 0.013-0.017g.

[0042] In the method described in this invention, the intestinal microorganisms of insects play a crucial role in the degradation and transformation of substrates. This invention utilizes the intestinal microorganisms of yellow mealworms and black soldier flies to pre-ferment straw or straw excrement, which effectively improves the chewability and degradability of straw, enhances the efficiency of insect cascade transformation of straw, and obtains high-protein insect bodies and excrement.

[0043] The *Penicillium janthinellum* PA01 strain described in this invention is deposited at the China Center for Type Culture Collection (CCTCC), accession number M2015757, deposit date: 2015-12-15, Wuhan University, Wuhan, China. This bacterium was initially found to increase the available phosphorus content in acidic soils, improve phosphate fertilizer utilization efficiency, and increase crop yields. Later research by the inventors revealed that this bacterium also has the function of degrading straw. Furthermore, this invention demonstrates that using a mixture of black soldier fly gut microbiota and *Penicillium janthinellum* PA01 for fermentation of straw and insect excrement can effectively improve the utilization efficiency of straw and insect excrement by black soldier flies.

[0044] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0045] The LB liquid culture medium used in the following examples was prepared as follows: 10g of peptone, 5g of yeast powder and 10g of sodium chloride were added to 1L of deionized water, and the pH of the solution was adjusted to 7.0-7.2 with 1mol / L sodium hydroxide. Then, the solution was autoclaved at 121℃ for 30min and cooled for later use.

[0046] The preparation method of PDB liquid culture medium used in the following examples is as follows: 200g of peeled potatoes are added to 1L of deionized water, heated and boiled for 30min, and then filtered with gauze to collect the filtrate; 20g of glucose is added to the filtrate, and then deionized water is added to make up to 1L, followed by autoclaving at 121℃ for 30min, and then cooled for use.

[0047] Unless otherwise specified, the techniques or conditions described in the following examples are based on those described in the literature or the product instructions. Unless otherwise specified, the reagents or instruments used are all commercially available products.

[0048] Example 1

[0049] This example uses corn stalks to provide a method for promoting the cascade conversion of corn mealworms and black soldier flies into high-protein insect bodies from corn stalks. The method includes the following steps:

[0050] (1) Enrichment culture of intestinal microorganisms of yellow mealworms.

[0051] Thirty mealworms were collected, and their surfaces were disinfected with 75% alcohol and washed three times with sterile water. Under aseptic conditions, the mealworms were dissected, and their intestines were placed in 1 mL of 0.9% physiological saline and ground into a homogenate using a mortar. The homogenate was diluted 10-fold with sterile water, and 2 mL of the diluted homogenate was inoculated into 100 mL of LB liquid medium. Another 2 mL of the diluted homogenate was inoculated into 100 mL of LPDB liquid medium. The medium was incubated at 30℃ and 180 rpm in an air shaker for 72 h to obtain enriched mealworm intestinal bacterial suspension A and fungal suspension B. Suspension A and suspension B were then mixed in equal volumes to obtain mealworm intestinal microbial suspension C.

[0052] (2) Pre-fermentation of straw by intestinal microorganisms of yellow mealworms.

[0053] 350g of corn stalks less than 5cm in length were placed in a polyethylene bag, and 817mL of deionized water was added to adjust the moisture content of the stalks to 70%. 35mL of the yellow mealworm intestinal microbial inoculum C from step (1) was inoculated, and the mixture was thoroughly mixed and sealed. The mixture was then anaerobic fermented at 30±2℃ for 7 days to obtain corn stalks pre-fermented with yellow mealworm intestinal microorganisms.

[0054] (3) Fermented straw is used to feed mealworms.

[0055] Take 25g of corn stalks pre-fermented with intestinal microorganisms of yellow mealworms obtained in step (2) and add them to the rearing basin. Inoculate 370 yellow mealworm larvae with an age of 75 days, a fresh weight of 24.0g, and a straw thickness of 2.0cm. Reare them for 48 days at a temperature of 27±2℃ and a humidity of 65±5%. During the rearing period, feed the yellow mealworm larvae 4g of carrots with a moisture content of 92% every 3 days to supplement the water required by the yellow mealworm larvae.

[0056] After the rearing period, mealworms, corn stalk frass, and remaining corn stalks were collected. The fresh weight of the mealworm larvae was measured, and the dry weight was further measured using a freeze-drying method. The results showed that the mealworms consumed 16.31g of stalks, with a stalk consumption rate of 65.24%, and the survival rate was 97.9%. The fresh weight of the mealworms increased by 17.89g, representing a fresh weight growth rate of 74.54%. The dry weight of the mealworms increased from 8.44g to 10.39g, representing a dry weight growth rate of 23.10%.

[0057] (4) Enrichment culture of black soldier fly intestinal microorganisms.

[0058] Thirty black soldier flies were taken, and their surfaces were disinfected with 75% alcohol and washed three times with sterile water. Under aseptic conditions, the black soldier flies were dissected, and their intestines were placed in 1 mL of 0.9% physiological saline and ground into a homogenate using a mortar. The homogenate was diluted 10 times with sterile water, and 2 mL of the diluted homogenate was inoculated into 100 mL of LB liquid medium. Another 2 mL of the diluted homogenate was inoculated into 100 mL of LPDB liquid medium. The medium was incubated in an air shaker at 30°C and 180 rpm for 72 h to obtain enriched black soldier fly intestinal bacterial suspension D and fungal suspension E. Suspension D and suspension E were then mixed in equal volume ratio to obtain black soldier fly intestinal microbial suspension F.

[0059] (5) Cultivation of Penicillium micropurpurum PA01.

[0060] Take 2 mL of PA01 bacterial suspension and inoculate it into 100 mL of PDA liquid medium. Place the medium in an air shaker at 30℃ and 180 rpm for 72 h to obtain the micropurus purpureus PA01 bacterial suspension G.

[0061] (6) Black soldier fly intestinal microorganisms and Penicillium micropurus PA01 mixed fermentation of straw and insect excrement.

[0062] 25g of corn stalk insect excrement from step (3) was placed into a polyethylene bag, and 75mL of deionized water was added to adjust the moisture content of the straw insect excrement to 75%. 1.25mL of black soldier fly intestinal microbial inoculum solution F from step (4) and 1.25mL of Penicillium microbiota PA01 inoculum solution from step (5) were inoculated separately. After thorough mixing, the bag was sealed and anaerobic fermented at 30℃ for 7 days to obtain mixed fermented corn stalk insect excrement.

[0063] (7) Fermented straw and insect excrement are used to feed black soldier flies.

[0064] Add the mixed fermented corn stalk and insect excrement with a dry weight of 10g and a moisture content of 75% from step (6) into the rearing basin, inoculate with 60 black soldier fly larvae, 5 days old, with a fresh weight of 0.893g, and the corn stalk and insect excrement thickness of 2.5cm. The black soldier flies were reared for 14 days under the conditions of a temperature of 30±2℃ and a humidity of 75±5%.

[0065] After the rearing period, black soldier flies and remaining frass were collected. The fresh weight of the black soldier flies was measured, and the dry weight was further measured using a freeze-drying method. The results showed that the survival rate of the black soldier flies was 96.7%, the fresh weight increased by 4.738 g, and the fresh weight growth rate was 530.65%; the dry weight of the black soldier flies increased from 0.320 g to 1.078 g, and the dry weight growth rate was 237.28%.

[0066] Example 2

[0067] This example uses rapeseed straw to provide a method for promoting the cascade conversion of yellow mealworms and black soldier flies into high-protein insect bodies from straw, specifically including the following steps:

[0068] (1) Enrichment culture of intestinal microorganisms of yellow mealworms is consistent with step (1) of Example 1.

[0069] (2) Pre-fermentation of straw by intestinal microorganisms of yellow mealworms.

[0070] 350g of rapeseed straw with a length of less than 5cm was placed in a polyethylene bag, and 825mL of deionized water was added to adjust the straw moisture content to 70.2%. 35mL of the yellow mealworm intestinal microbial inoculum C from step (1) was inoculated, and the mixture was thoroughly mixed and sealed. The mixture was then anaerobic fermented at 30±2℃ for 7 days to obtain pre-fermented rapeseed straw with yellow mealworm intestinal microorganisms.

[0071] (3) Fermented straw is used to feed mealworms.

[0072] Take 25g of rapeseed straw pre-fermented by the intestinal microorganisms of yellow mealworms in step (2) and add it to the rearing basin. Inoculate 370 yellow mealworm larvae with an age of 75 days, a fresh weight of 24.0g, and a straw thickness of 2.0cm. Reare them for 48 days at a temperature of 27±2℃ and a humidity of 65±5%. During the rearing period, feed 4g of carrots with a water content of 92% every 3 days to supplement the water required by the yellow mealworm larvae.

[0073] After the rearing period, mealworm excrement, rapeseed straw, and remaining rapeseed straw were collected. The fresh weight of the mealworm larvae was measured, and the dry weight was further measured using a freeze-drying method. The results showed that the mealworms consumed 14.04 g of straw, with a straw consumption rate of 56.16%, and the survival rate of the mealworms was 97.8%. The fresh weight of the mealworms increased by 14.01 g, with a fresh weight growth rate of 58.38%. The dry weight of the mealworms increased from 8.44 g to 9.48 g, with a dry weight growth rate of 12.32%.

[0074] (4) The enrichment culture of black soldier fly intestinal microorganisms is the same as step (4) in Example 1.

[0075] (5) The culture of Penicillium micropurpurum PA01 is the same as step (5) in Example 1.

[0076] (6) Black soldier fly intestinal microorganisms and Penicillium micropurus PA01 mixed fermentation of straw and insect excrement.

[0077] 25g of rapeseed straw insect excrement from step (3) was placed into a polyethylene bag, and 78mL of deionized water was added to adjust the moisture content of the straw insect excrement to 75.7%. 1.25mL of black soldier fly intestinal microbial inoculum F from step (4) and 1.25mL of Penicillium microbiota PA01 inoculum from step (5) were inoculated separately. After thorough mixing, the bag was sealed and anaerobic fermented at 30℃ for 7 days to obtain mixed fermented rapeseed straw insect excrement.

[0078] (7) Fermented straw and insect excrement are used to feed black soldier flies.

[0079] Add the mixed fermented corn stalk and insect excrement with a dry weight of 10g and a moisture content of 75.7% from step (6) into the rearing basin, inoculate with 60 black soldier fly larvae, 5 days old, with a fresh weight of 0.910g, and the insect excrement thickness of 2.5cm. Reare the black soldier flies for 14 days at a temperature of 30±2℃ and a humidity of 75±5%.

[0080] After the rearing period, black soldier flies and their remaining excrement were collected. The fresh weight of the black soldier flies was measured, and their dry weight was further measured using a freeze-drying method. The results showed that the survival rate of the black soldier flies was 95.3%, the fresh weight increased by 4.310 g, and the fresh weight growth rate was 473.85%; the dry weight of the black soldier flies increased from 0.326 g to 1.078 g, and the dry weight growth rate was 218.36%.

[0081] Comparative Example 1

[0082] This example uses corn stalks to feed mealworms and black soldier flies through the following process, and then examines the obtained insects:

[0083] (1) Feed mealworms directly with corn stalks, and the feeding conditions are the same as step (3) in Example 1.

[0084] (2) The corn stalks and insect excrement obtained in step (1) are used to feed black soldier flies directly, and the feeding conditions are the same as in step (7) of Example 1.

[0085] The results showed (using the same detection method as in Example 1) that, in the stage of directly feeding mealworms with corn stalks, the mealworms consumed 15.84g of stalks, with a stalk consumption rate of 63.36% and a survival rate of 99.3%. The fresh weight of the mealworms increased by 10.52g, representing a growth rate of 43.83%, and their dry weight increased from 8.44g to 9.14g, representing a growth rate of 8.29%. In the stage of directly feeding black soldier flies with corn stalk and mealworm excrement, the survival rate of the black soldier flies was 93.33%, their fresh weight increased by 2.492g, representing a growth rate of 273.82%, and their dry weight increased from 0.326g to 0.680g, representing a growth rate of 108.74%.

[0086] Comparative Example 2

[0087] This example uses corn stalks to feed mealworms and black soldier flies through the following process:

[0088] (1) Feed mealworms directly with corn stalks, and the feeding conditions are the same as step (3) in Example 1.

[0089] (2) The enrichment culture of black soldier fly gut microbiota is the same as step (4) in Example 1.

[0090] (3) The corn straw insect excrement obtained by fermenting step (1) with black soldier fly intestinal microorganisms was fermented under the same conditions as step (6) in Example 1.

[0091] (4) Use the black soldier fly gut microbiota obtained in step (3) to ferment corn straw and insect excrement to feed black soldier flies. The feeding conditions are the same as in step (7) of Example 1.

[0092] The obtained mealworms and black soldier flies were tested according to Example 1. The experimental results of directly feeding mealworms with corn stalks were the same as those of Comparative Example 1. The results of feeding black soldier flies with corn stalk excrement fermented by intestinal microorganisms were as follows: the survival rate of black soldier flies was 91.67%, the fresh weight increased by 2.603g, and the fresh weight growth rate was 291.52%; the dry weight of black soldier flies increased from 0.320g to 0.724g, and the dry weight growth rate was 126.52%.

[0093] Comparative Example 3

[0094] This example uses corn stalks to feed mealworms and black soldier flies through the following process:

[0095] (1) Feed mealworms directly with corn stalks, and the feeding conditions are the same as step (3) in Example 1.

[0096] (2) The culture of Penicillium micropurpurum PA01 is the same as step (5) in Example 1.

[0097] (3) Ferment corn straw insect excrement obtained in step (1) using Penicillium micropurus PA01, under the same fermentation conditions as step (6) in Example 1.

[0098] (4) Use the micropurus purpureus PA01 obtained in step (3) to ferment corn straw and insect excrement to feed black soldier flies. The feeding conditions are the same as in step (7) of Example 1.

[0099] The obtained mealworms and black soldier flies were tested according to Example 1. The experimental results of directly feeding mealworms with corn stalks were the same as those of Comparative Example 1. The results of feeding black soldier flies with corn stalk mealworm excrement fermented by Penicillium micropurpurum PA01 were as follows: the survival rate of black soldier flies was 95.50%, the fresh weight increased by 3.110g, and the fresh weight growth rate was 347.34%; the dry weight of black soldier flies increased from 0.321g to 0.828g, and the dry weight growth rate was 158.34%.

[0100] Comparison of the growth rate of mealworm body weight during the cascade conversion of corn straw by yellow mealworms and black soldier flies under different treatment conditions, for example Figure 2 As shown in the figure, the efficiency of directly feeding mealworms with corn stalks and then directly feeding black soldier flies with their excrement was the lowest. The fresh weight increase of mealworms was 43.83%, and the dry weight increase was 8.29%, while the fresh weight increase of black soldier flies was 273.82%, and the dry weight increase was 108.74%. The highest efficiency was achieved when corn stalks were pre-fermented with mealworm intestinal microorganisms, and then the excrement was fermented with a mixture of mealworm intestinal microorganisms and *Penicillium purpureus* PA01 before feeding black soldier flies. The fresh weight increase of mealworms was 74.54%, and the dry weight increase was 23.10%, while the fresh weight increase of black soldier flies was 530.65%, and the dry weight increase was 237.28%.

[0101] In summary, this invention first uses the intestinal microorganisms of yellow mealworms to pre-ferment straw, and then uses the intestinal microorganisms of black soldier flies and Penicillium micropurus PA01 to ferment the straw and insect excrement. This can significantly improve the efficiency of yellow mealworm-black soldier fly cascade conversion of straw for high-protein insect body recovery. This invention provides a new approach for the efficient utilization of straw and the breeding of yellow mealworms and black soldier flies.

[0102] The above description is a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw, characterized in that, Includes the following steps: S1. Pre-fermenting straw with intestinal microorganisms of mealworms, wherein the intestinal microorganisms of mealworms include bacteria and fungi derived from the intestines of mealworms; S2. Use the pre-fermented straw obtained in step S1 to feed mealworms and obtain straw worm excrement; S3. Ferment straw and insect excrement by mixing black soldier fly intestinal microorganisms and Penicillium micropurus PA01. The preservation number of Penicillium micropurus PA01 is CCTCCNO: M2015757. The black soldier fly intestinal microorganisms include bacteria and fungi derived from the black soldier fly intestine. S4. Use the fermentation product obtained from S3 to feed black soldier flies.

2. The method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw, as described in claim 1, is characterized in that... The straw includes corn straw, rapeseed straw, rice straw, wheat straw, and water hyacinth straw, and the length of the straw is <5cm.

3. The method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw according to claim 1, characterized in that, The intestinal microorganisms of the yellow mealworm are prepared by the following process: the intestines of the yellow mealworm are placed in physiological saline, ground into a homogenate, and the homogenate is inoculated into LB medium for culture to obtain the bacterial culture of the yellow mealworm intestine. The homogenate is inoculated into PDB medium for culture to obtain the fungal culture of the yellow mealworm intestine. The bacterial culture and the fungal culture are mixed to obtain the final product. The intestinal microorganisms of the black soldier fly are prepared by the following process: black soldier fly intestines are placed in physiological saline, ground into a homogenate, and the homogenate is inoculated into LB medium for culture to obtain the bacterial culture of the black soldier fly intestine. The homogenate is then inoculated into PDB medium for culture to obtain the fungal culture of the black soldier fly intestine. The bacterial culture and the fungal culture are then mixed to obtain the final product.

4. The method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw according to claim 1, characterized in that, The pre-fermentation conditions described in step S1 are as follows: adjust the moisture content of the straw to 70-75%, inoculate with intestinal microorganisms of mealworms, mix well, and anaerobic ferment at 30-35°C.

5. The method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw according to claim 1, characterized in that, The rearing conditions described in step S2 are as follows: 10-15 mealworms are placed for every 1g of pre-fermented straw, the straw thickness is 1.5-2.5cm, the temperature is 27±2°C, the humidity is 65±5%, and the rearing period is 40-60 days. Carrots or green vegetable leaves are fed every 3 days to supplement the water of the mealworm larvae.

6. The method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw according to claim 5, characterized in that, The mealworms mentioned in step S2 are mealworm larvae fed with wheat bran, with an age of 60-80 days, a body length of 1.5-2.5 cm, and an individual weight of 0.06-0.08 g.

7. The method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw according to claim 1, characterized in that, The conditions for mixed fermentation in step S3 are as follows: the moisture content of straw and insect excrement is adjusted to 75-80%, black soldier fly intestinal microorganisms and Penicillium micropurus PA01 are inoculated and then mixed, and anaerobic fermentation is carried out at 30-35°C.

8. The method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw according to claim 1, characterized in that, The rearing conditions described in step S4 are as follows: 5 to 7 black soldier flies are prepared for every 1g of straw frass, the straw frass is 2.0 to 3.0cm thick, and the black soldier flies are reared for 12 to 15 days at a temperature of 30±2°C and a humidity of 75±5%.

9. The method for promoting the cascade conversion of mealworms and black soldier flies into high-protein insect bodies from straw according to claim 8, characterized in that, Step S4: The black soldier fly larvae are black soldier fly larvae fed with soybean meal. The larvae are 4-6 days old, with a body length of 0.5-1.0 cm and an individual weight of 0.013-0.017 g.

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