Bacillus amyloliquefaciens aqueous solution as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of microorganisms, and relates to a bacillus amyloliquefaciens aqueous solution as well as a preparation method and application thereof. The invention provides a bacillus amyloliquefaciens aqueous solution, the bacillus amyloliquefaciens is bacillus amyloliquefaciens YJNbs21.10, the bacillus amyloliquefaciens is preserved in the China General Microbiological Culture Collection Center (CGMCC), and the preservation number is CGMCC No.25798. The bacillus amyloliquefaciens aqueous solution has the advantages that the bacillus amyloliquefaciens is bacillus amyloliquefaciens YJNbs21.10, the bacillus amyloliquefaciens is preserved in the China General Microbiological Culture Collection Center (CGMCC); the bacillus amyloliquefaciens aqueous solution is prepared from APG1214, Tween 20, sodium carboxymethyl cellulose, ethylene glycol, ascorbic acid, sodium dodecyl benzene sulfonate and bacillus amyloliquefaciens fermentation liquor. The invention can provide a new scheme for promoting sustainable development of green agriculture.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology and relates to an aqueous solution of Bacillus amyloliquefaciens, its preparation method and application. Background Technology

[0002] In recent years, the extensive use of chemical pesticides has caused environmental pollution and led to pesticide resistance in agricultural and forestry pests, weakening the effectiveness of traditional insecticides. Therefore, the search for new insecticides has become a hot topic. Among the many types of insecticides, microbial insecticides have come into focus due to their targeted nature, safety, and high efficiency.

[0003] Bacillus amyloliquefaciens ( Bacillus amyloliquefa—ciens ) belongs to the genus Bacillus ( Bacillus sp. Bacillus amyloliquefaciens (BAM) is widely distributed in nature and possesses abundant metabolites. Its secreted antibiotics, antibacterial proteins, and polypeptides provide effective biological control. It is a globally recognized biocontrol bacterium, characterized by rapid growth, long shelf life, and the ability to produce resistant spores. After application, it colonizes the host surface and forms a protective layer, thus blocking the infection of various pathogens. In the field of plant pest control, studies have shown that BAM has a certain control effect on tomato leafminer. Treatment with BAM through methods such as leaf dipping significantly increased the mortality rate of cereal aphids and wheat aphids. Field trials showed a significant reduction in the number of winged and wingless aphids in wheat fields, and it was harmless to parasitic wasps, the natural enemies of wheat aphids. Drip irrigation application of BAM HN11 can promote the absorption of tetrachlorantraniliprole in corn, enhancing the control effect against fall armyworm.

[0004] Aphids, also known as plant lice or honeydew insects, are a type of herbivorous insect belonging to the family Aphididae in the order Hemiptera, including the superfamilies Aphididae and Aphidoidea. They are tiny (usually 1-10 mm) with soft bodies and diverse colors (green, yellow, black, etc.). They possess piercing-sucking mouthparts and are among the most destructive pests on Earth. Both adults and nymphs damage plants. Initially, they cause leaf curling and inhibit growth by sucking sap; later, honeydew accumulation induces sooty mold. They also act as vectors for various viral diseases, causing mosaic patterns, yellowing flowers, and leaf curling in crops, becoming a major threat to stable crop yields. Whiteflies, also known as greenhouse whiteflies, belong to the family Amyliidae in the order Hemiptera and are commonly called small white moths. They are a global agricultural pest. Both adults and nymphs damage plants, and their wide spread and strong resistance to pesticides have made them one of the main threats to greenhouse, polytunnel, and open-field crops. Their powerful reproductive and dispersal capabilities pose a multi-dimensional threat to agricultural production, causing significant damage in the agricultural and forestry sectors. Whiteflies, as important vectors of plant viruses, cause even more severe indirect damage. By feeding on infected plants and then biting healthy ones, whiteflies can rapidly spread various viruses, such as tomato yellow leaf curl virus and cucumber chlorosis virus, leading to large-scale epidemics of viral diseases among crops. Once viral diseases break out, they are often difficult to control effectively with chemical methods, frequently resulting in large-scale yield reductions or even crop failure, causing losses far exceeding those caused by the direct feeding of whiteflies. Summary of the Invention

[0005] The purpose of this invention is to provide a Bacillus amyloliquefaciens aqueous solution and its preparation method, to establish and test the key indicators of the Bacillus amyloliquefaciens aqueous solution, and then to apply it in the field, laying the foundation for the industrial application of Bacillus amyloliquefaciens aqueous solution, and also to develop a new biocontrol agent for the biological control of aphids and whiteflies.

[0006] To achieve the above objectives, the present invention provides the following technical solution: On one hand, the present invention provides an aqueous solution of Bacillus amyloliquefaciens, wherein the Bacillus amyloliquefaciens is Bacillus amyloliquefaciens. Bacillus amyloliquefaciens YJNbs21.10 is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 25798; the Bacillus amyloliquefaciens aqueous solution comprises APG1214 (decyl glucoside), Tween 20, sodium carboxymethyl cellulose, ethylene glycol, ascorbic acid, sodium dodecylbenzene sulfonate, and Bacillus amyloliquefaciens fermentation broth.

[0007] Preferably, 100 mL of the Bacillus amyloliquefaciens aqueous solution comprises 10 g APG1214, 5 mL Tween 20, 1.5 g sodium carboxymethyl cellulose, 15 mL ethylene glycol, 0.2 g ascorbic acid, 3 g sodium dodecylbenzenesulfonate, and the remainder being Bacillus amyloliquefaciens fermentation broth.

[0008] Preferably, the method for preparing the Bacillus amyloliquefaciens fermentation broth is as follows: The Bacillus amyloliquefaciens strain YJNbs21.10 was activated on PDA medium and cultured at 28°C for 3-4 days. A sterile inoculation loop was used to scrape the activated Bacillus amyloliquefaciens YJNbs21.10 bacterial colony from the PDA medium and transferred it to a sterile test tube containing sterile physiological saline. The colony was then shaken to disperse the Bacillus amyloliquefaciens YJNbs21.10 bacterial colony in the saline, thus preparing a suspension of Bacillus amyloliquefaciens YJNbs21.10. Subsequently, the Bacillus amyloliquefaciens YJNbs21.10 bacterial suspension was diluted to control the concentration at the order of 10 cells / mL. The Bacillus amyloliquefaciens YJNbs21.10 bacterial suspension was then inoculated into the fermentation medium at a volume ratio of 5% and cultured at 28℃ and 150 r / min for 72 h to obtain the original fermentation broth of Bacillus amyloliquefaciens YJNbs21.10 strain. The fermentation medium consists of 3 g / L beef extract, 10 g / L peptone, 5 g / L NaCl, and 1 L distilled water.

[0009] On the other hand, a method for preparing the Bacillus amyloliquefaciens aqueous solution according to the present invention is provided, the preparation method comprising the following steps: (1) Weigh 10g of APG1214 and add 10mL of Bacillus amyloliquefaciens fermentation broth. Heat in a 60℃ water bath until it melts and becomes transparent. (2) Add 1.5g of sodium carboxymethyl cellulose while it is still hot and stir thoroughly; (3) After cooling, add 5 mL of Tween 20, 15 mL of ethylene glycol, 0.2 g of ascorbic acid, and 3 g of sodium dodecylbenzenesulfonate in sequence, and then add Bacillus amyloliquefaciens fermentation broth to make up to 100 mL; (4) Mix them thoroughly until foam is produced, cover with plastic wrap and let stand; (5) Once the foam has completely disappeared, the aqueous solution of Bacillus amyloliquefaciens is obtained.

[0010] On the other hand, a method for detecting key indicators of the Bacillus amyloliquefaciens aqueous solution described in this invention is provided, the method comprising: Dilute the Bacillus amyloliquefaciens fermentation broth to 10... -6 The suspension was pipetted 100 μL and evenly spread on the surface of PDA medium. It was then placed in a 37°C incubator and incubated until single colonies grew. The number of colonies was counted to determine the viable count.

[0011] Preferably, the viable count of the Bacillus amyloliquefaciens aqueous solution is 2.5 × 10⁻⁶. 9 CFU / mL.

[0012] On the other hand, an agricultural composition is provided, the agricultural composition comprising the Bacillus amyloliquefaciens aqueous solution described in this invention.

[0013] On the other hand, the present invention provides the application of the Bacillus amyloliquefaciens aqueous solution in the control of agricultural plant pests.

[0014] Preferably, the pests include adult strawberry aphids, peach aphids, and whiteflies.

[0015] On the other hand, the present invention provides the application of the agricultural composition in the control of agricultural plant pests, including adult strawberry aphids, peach aphids, and whiteflies.

[0016] It should be noted that the Bacillus amyloliquefaciens described in this invention is Bacillus amyloliquefaciens. Bacillus amyloliquefaciens YJNbs21.10, the Bacillus amyloliquefaciens described therein is deposited at the China General Microbiological Culture Collection Center, with accession number CGMCC No.25798. For details, please refer to patent CN116121137A.

[0017] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: (1) The present invention develops a Bacillus amyloliquefaciens aqueous solution by adding various adjuvants to the secondary fermentation broth of Bacillus amyloliquefaciens YJNbs21.10. The Bacillus amyloliquefaciens aqueous solution has the activity of controlling aphids (strawberry aphids, peach aphids) and whiteflies.

[0018] (2) This invention clarifies the key indicator detection method for Bacillus amyloliquefaciens aqueous solution.

[0019] (3) The Bacillus amyloliquefaciens aqueous solution of this invention showed good control effects against aphids and whiteflies, providing important strain resources and theoretical basis for the development of new microbial pesticides. The successful development of this aqueous solution has promoted the field application of Bacillus amyloliquefaciens YJNbs21.10 biocontrol agents, providing a new solution for promoting the sustainable development of green agriculture. Specifically, after field efficacy trials, the aqueous solution achieved a 99.60% reduction rate in aphid populations of greenhouse strawberries 15 days after application; a corrected control efficacy of 82.34% against peach aphids 7 days after application, increasing to 98.77% after 15 days; and a corrected control efficacy of 90.36% against whiteflies 7 days after application.

[0020] (4) Based on the technical solution of the present invention, it can be predicted that the Bacillus amyloliquefaciens YJNbs21.10 has good development and application prospects in the fields of microbial pesticides, microbial preparations and other agricultural pest and disease control. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 Bacillus amyloliquefaciens Bacillus amyloliquefaciens The front view of the colony morphology of strain YJNbs21.10 after culturing on PDA medium for 3 days.

[0023] Figure 2 Bacillus amyloliquefaciens Bacillus amyloliquefaciens Image of secondary seed liquid of strain YJNbs21.10 after 3 days of fermentation.

[0024] Figure 3 Bacillus amyloliquefaciens Bacillus amyloliquefaciens Image of the fermentation broth after 3 days of fermentation of strain YJNbs21.10.

[0025] Figure 4 A diagram of Bacillus amyloliquefaciens aqueous solution.

[0026] Figure 5 A graph showing the bacterial count results for determining key indicators of Bacillus amyloliquefaciens aqueous solution.

[0027] Figure 6 Comparison of strawberry aphids 15 days before and after application of Bacillus amyloliquefaciens aqueous solution (A is before application, B is 15 days after application).

[0028] Figure 7 Comparison of peach aphids 15 days before and after application of Bacillus amyloliquefaciens aqueous solution (A is before application, B is 15 days after application).

[0029] Figure 8 Comparison of adult whiteflies 15 days before and after application of Bacillus amyloliquefaciens aqueous solution (A: before application, B: 15 days after application). Detailed Implementation

[0030] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods and detection methods described in each embodiment are conventional methods; unless otherwise specified, the reagents and materials can be purchased commercially.

[0031] Example 1 This embodiment provides information on Bacillus amyloliquefaciens. Bacillus amyloliquefaciensCultivation and fermentation of strain YJNbs21.10 The *Bacillus amyloliquefaciens* strain YJNbs21.10 was activated using PDA medium (200g potato, 20g glucose, 20g agar, 1000mL water) and cultured at 28℃ for 3 days. Figure 1 (As shown); Using a sterile inoculation loop, scrape the *Bacillus amyloliquefaciens* YJNbs21.10 bacterial colony from the activated PDA medium and transfer it to a sterile test tube containing sterile physiological saline. Shake to disperse the *Bacillus amyloliquefaciens* YJNbs21.10 bacterial colony in the physiological saline, thus preparing a *Bacillus amyloliquefaciens* YJNbs21.10 bacterial suspension (e.g., ...). Figure 2 (As shown); Subsequently, the *Bacillus amyloliquefaciens* YJNbs21.10 bacterial suspension was diluted to control the concentration at the order of 10 cells / mL; the *Bacillus amyloliquefaciens* YJNbs21.10 bacterial suspension was inoculated into fermentation medium (composed of: 3 g / L beef extract, 10 g / L peptone, 5 g / L NaCl and 1 L distilled water) at a volume ratio of 5%, and cultured at 28℃ and 150 r / min for 72 h with shaking to obtain the original fermentation broth of *Bacillus amyloliquefaciens* YJNbs21.10 strain (as shown). Figure 3 (As shown).

[0032] Depend on Figure 1 It was found that after culturing Bacillus amyloliquefaciens strain YJNbs21.10 on PDA medium for 3 days, it formed colonies with a specific morphology, exhibiting wrinkled or filamentous textures on the colony surface. Figure 2 , Figure 3 It can be seen that after 3 days of fermentation, the *Bacillus amyloliquefaciens* strain YJNbs21.10 produced a fermentation broth. Both the secondary seed culture and the fermentation broth were turbid yellow, indicating that the strain produced metabolic products during fermentation, causing changes in the liquid's appearance. Furthermore, the color and turbidity of the fermentation broth in multiple conical flasks were relatively consistent, indicating that the fermentation process of this strain has good repeatability and stability, maintaining similar growth and metabolic states in different culture containers. Overall, Figures 1-3 This indicates that Bacillus amyloliquefaciens YJNbs21.10 can grow on PDA medium and form characteristic colonies, and can stably produce metabolites during liquid fermentation, providing a basis for further research on the characteristics and applications of this strain.

[0033] Example 2 This embodiment describes the preparation and key indicator determination of Bacillus amyloliquefaciens aqueous solution. The preparation method of Bacillus amyloliquefaciens aqueous solution includes the following steps: (1) Weigh 10g APG1214 and add 10mL of Bacillus amyloliquefaciens fermentation broth, place it in a 60℃ water bath and heat until it melts and becomes transparent; (2) While it is hot, add 1.5g sodium carboxymethyl cellulose and stir thoroughly; (3) After cooling, add 5mL Tween 20, 15mL ethylene glycol, 0.2g ascorbic acid, and 3g sodium dodecylbenzene sulfonate in sequence, and then add Bacillus amyloliquefaciens fermentation broth to make up to 100mL; (4) Mix it thoroughly until foam is produced, cover it with plastic wrap and let it stand; (5) When the foam completely disappears, Bacillus amyloliquefaciens aqueous solution is obtained. Figure 4 ).

[0034] The key indicator detection method for Bacillus amyloliquefaciens aqueous solution is as follows: dilute the Bacillus amyloliquefaciens fermentation broth to 10... -6 The suspension was pipetted 100 μL and evenly spread on the surface of PDA medium. The medium was then incubated at 37°C until single colonies appeared. The number of colonies was counted to determine the viable count. Figure 5 ).

[0035] Depend on Figure 4 It can be seen that the Bacillus amyloliquefaciens aqueous solution formed a stable emulsion suspension system, exhibiting a turbid, milky appearance. The Bacillus amyloliquefaciens fermentation broth, as the main component, together with other substances in the aqueous solution, formed this specific appearance, indicating that the components in the Bacillus amyloliquefaciens aqueous solution formulation could mix well and form a relatively stable system, indicating successful preparation of the aqueous solution. Figure 5 As can be seen, multiple white colonies were distributed on the PDA medium, indicating that the *Bacillus amyloliquefaciens* in the aqueous solution could still maintain its activity and grow and reproduce normally. The various components in the aqueous solution formulation did not significantly inhibit the activity of the bacteria. The amount of *Bacillus amyloliquefaciens* in the solution reached a detectable and sufficient level, and the large number of colonies indicates that the aqueous solution formulation of this invention is effective in maintaining bacterial activity. Overall, Figure 4 and Figure 5 The study confirmed that the aqueous formulation of Bacillus amyloliquefaciens can produce a product that is physically stable and contains live bacteria, which is valuable for further development and application.

[0036] Example 3 This embodiment presents a field efficacy test of Bacillus amyloliquefaciens aqueous solution (Bacillus amyloliquefaciens YJNbs21.10 aqueous solution) for controlling strawberry aphids.

[0037] In this experiment, Bacillus amyloliquefaciens YJNbs21.10 aqueous solution was diluted 300 times to form the treatment group, with water as the negative control. Each treatment was replicated four times. The experimental area was 10 m². 2The strawberry aphid population was randomly assigned to blocks. A manual sprayer was used for uniform spraying. Before application, the initial strawberry aphid population was assessed, and a manual sprayer was used for uniform spraying. Leaf tags were used to pin the leaves in each treatment group, and the number of aphids on each leaf was recorded during the assessment. The aphid population reduction rate was recorded at 1, 3, 5, 7, 11, and 15 days after application. The field trial was conducted in April 2025 in strawberry greenhouses No. 3 and No. 5 of Liangdongchang Village, Zhaixi Village, Yangling District, Xianyang City, Shaanxi Province. The results are shown in Table 1. Figure 6 .

[0038] This embodiment uses the insect population reduction rate to evaluate the control effect, and the relevant formula is as follows:

[0039] Table 1. Field efficacy results of Bacillus amyloliquefaciens YJNbs21.10 aqueous solution for controlling strawberry aphids.

[0040] The experimental results in Table 1 show that Bacillus amyloliquefaciens YJNbs21.10 aqueous solution has good control efficacy against strawberry aphids. When Bacillus amyloliquefaciens YJNbs21.10 aqueous solution is diluted 300 times, the aphid population reduction rate reaches 98.53% 7 days after application, and the maximum reduction rate of 99.60% is reached 15 days after application.

[0041] Depend on Figure 6 It can be seen that before the application of the pesticide, the number of strawberry aphids was relatively large and their distribution was relatively dense; however, 15 days after the application, the number of strawberry aphids decreased significantly, and it was almost impossible to observe a large number of aphids. This indicates that the Bacillus amyloliquefaciens aqueous solution of the present invention has a good control effect on strawberry aphids and can significantly reduce the population density of strawberry aphids within a certain period of time.

[0042] Example 4 This embodiment presents a field efficacy test of Bacillus amyloliquefaciens YJNbs21.10 aqueous solution for controlling peach aphids.

[0043] In this experiment, Bacillus amyloliquefaciens YJNbs21.10 aqueous solution was diluted 300 times as the treatment group, with water as the negative control. Each treatment was repeated four times. The pesticide was applied using a manual sprayer for uniform spraying. Before application, the initial population of peach aphids was assessed, and the pesticide was applied uniformly using a manual sprayer. The number of peach aphids per leaf was recorded during the assessment. The population reduction rate and corrected control efficacy were calculated at 1, 3, 5, 7, 11, and 15 days after application. The field trial was conducted in May 2025 on red-leaf peach trees at the Northwest A&F University Water-Saving Irrigation Experimental Station in Yangling District, Xianyang City, Shaanxi Province. The experimental results are shown in Table 2. Figure 7 .

[0044] This embodiment adopts To evaluate the effectiveness of prevention and control, the relevant formula is as follows:

[0045] Table 2. Field efficacy results of Bacillus amyloliquefaciens YJNbs21.10 aqueous solution for controlling peach mealybug.

[0046] Table 2 shows the field efficacy results of Bacillus amyloliquefaciens YJNbs21.10 aqueous solution in controlling peach aphids. The results indicate that when Bacillus amyloliquefaciens YJNbs21.10 aqueous solution is diluted 300 times, it has a good but not high early-stage control effect on strawberry aphids, indicating that the aqueous solution has a weak fast-acting effect but a good residual effect. The corrected control efficacy exceeded 98.77% after 15 days.

[0047] Depend on Figure 7 It can be seen that before the application of the pesticide, peach aphids were widely distributed on the plants, causing certain signs of damage. After 15 days of application, the number of peach aphids decreased significantly, and the aggregation of aphids on the plants was greatly improved. This indicates that the Bacillus amyloliquefaciens aqueous solution of the present invention also has a significant inhibitory and killing effect on peach aphids and can effectively control the population of peach aphids.

[0048] Example 5 This embodiment presents a field efficacy test of Bacillus amyloliquefaciens YJNbs21.10 aqueous solution for controlling adult whiteflies.

[0049] In this experiment, Bacillus amyloliquefaciens YJNbs21.10 aqueous solution was diluted 300 times as the treatment group, with water as the negative control. Each treatment was repeated four times. The pesticide was applied using a manual sprayer for uniform spraying. Before application, the whitefly population was assessed using a manual sprayer for uniform spraying. The number of whiteflies per leaf was recorded during the assessment. The population reduction rate and corrected control efficacy were calculated at 1, 3, 5, 7, 11, and 15 days after application. The field trial was conducted in June 2025 in Wang Shifu's Provence tomato greenhouse in Yangling District, Xianyang City, Shaanxi Province, and Liang Dongchang's No. 4 melon greenhouse in Zhaixi Village, Yangling District, Xianyang City, Shaanxi Province. The results are shown in Table 3. Figure 8 .

[0050] Table 3. Field efficacy results of Bacillus amyloliquefaciens YJNbs21.10 aqueous solution for controlling adult whiteflies.

[0051] Table 3 shows the field efficacy results of Bacillus amyloliquefaciens YJNbs21.10 aqueous solution for controlling peach white aphids. The experimental results show that when Bacillus amyloliquefaciens YJNbs21.10 aqueous solution is diluted 300 times, the control efficacy reaches the highest level of 98.58% 1 day after application, indicating that the aqueous solution has a strong rapid effect on whiteflies but a short duration of effect.

[0052] Depend on Figure 8It can be seen that the number of adult whiteflies was relatively large before the application of the pesticide; 15 days after the application, the number of adult whiteflies decreased significantly and their activity was significantly reduced; this indicates that the Bacillus amyloliquefaciens aqueous solution of the present invention also has a good control effect on adult whiteflies, which can reduce the number of adult whiteflies and reduce their damage to crops.

[0053] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope defined by the present invention.

Claims

1. An aqueous solution of Bacillus amyloliquefaciens, wherein the Bacillus amyloliquefaciens is Bacillus amyloliquefaciens. Bacillus amyloliquefaciens YJNbs21.10, deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 25798, is characterized by: The Bacillus amyloliquefaciens aqueous solution includes APG1214, Tween 20, sodium carboxymethyl cellulose, ethylene glycol, ascorbic acid, sodium dodecylbenzene sulfonate, and Bacillus amyloliquefaciens fermentation broth.

2. The Bacillus amyloliquefaciens aqueous solution according to claim 1, characterized in that, 100 mL of the Bacillus amyloliquefaciens aqueous solution comprises 10 g APG1214, 5 mL Tween 20, 1.5 g sodium carboxymethyl cellulose, 15 mL ethylene glycol, 0.2 g ascorbic acid, 3 g sodium dodecylbenzenesulfonate, and the remainder Bacillus amyloliquefaciens fermentation broth.

3. The Bacillus amyloliquefaciens aqueous solution according to claim 1 or 2, characterized in that, The preparation method of the Bacillus amyloliquefaciens fermentation broth is as follows: The Bacillus amyloliquefaciens strain YJNbs21.10 was activated on PDA medium and cultured at 28°C for 3-4 days. A sterile inoculation loop was used to scrape the activated Bacillus amyloliquefaciens YJNbs21.10 bacterial colony from the PDA medium and transferred it to a sterile test tube containing sterile physiological saline. The colony was then shaken to disperse the Bacillus amyloliquefaciens YJNbs21.10 bacterial colony in the saline, thus preparing a suspension of Bacillus amyloliquefaciens YJNbs21.

10. Subsequently, the Bacillus amyloliquefaciens YJNbs21.10 bacterial suspension was diluted to control the concentration at the order of 10 cells / mL. The Bacillus amyloliquefaciens YJNbs21.10 bacterial suspension was then inoculated into the fermentation medium at a volume ratio of 5% and cultured at 28℃ and 150 r / min for 72 h to obtain the original fermentation broth of Bacillus amyloliquefaciens YJNbs21.10 strain. The fermentation medium consists of 3 g / L beef extract, 10 g / L peptone, 5 g / L NaCl, and 1 L distilled water.

4. The method for preparing the Bacillus amyloliquefaciens aqueous solution according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) Weigh 10g of APG1214 and add 10mL of Bacillus amyloliquefaciens fermentation broth. Heat in a 60℃ water bath until it melts and becomes transparent. (2) Add 1.5g of sodium carboxymethyl cellulose while it is still hot and stir thoroughly; (3) After cooling, add 5 mL of Tween 20, 15 mL of ethylene glycol, 0.2 g of ascorbic acid, and 3 g of sodium dodecylbenzenesulfonate in sequence, and then add Bacillus amyloliquefaciens fermentation broth to make up to 100 mL; (4) Mix them thoroughly until foam is produced, cover with plastic wrap and let stand; (5) Once the foam has completely disappeared, the aqueous solution of Bacillus amyloliquefaciens is obtained.

5. The method for detecting key indicators of the Bacillus amyloliquefaciens aqueous solution according to claim 1 or 2, characterized in that, The key indicator detection methods include: Dilute the Bacillus amyloliquefaciens fermentation broth to 10... -6 The suspension was pipetted 100 μL and evenly spread on the surface of PDA medium. It was then placed in a 37°C incubator and incubated until single colonies grew. The number of colonies was counted to determine the viable count.

6. The key indicator detection method according to claim 5, characterized in that, The viable count of the Bacillus amyloliquefaciens aqueous solution is 2.5 × 10⁻⁶. 9 CFU / mL.

7. An agricultural composition, characterized in that, The agricultural composition includes the Bacillus amyloliquefaciens aqueous solution as described in claim 1 or 2.

8. The application of the Bacillus amyloliquefaciens aqueous solution according to claim 1 or 2 in the control of agricultural plant pests.

9. The application according to claim 8, characterized in that, The pests include adult strawberry aphids, peach aphids, and whiteflies.

10. The application of the agricultural composition according to claim 7 in the control of agricultural plant pests, characterized in that, The pests include adult strawberry aphids, peach aphids, and whiteflies.

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