Aspergillus oil suspending agent for preventing and treating spodoptera frugiperda as well as preparation method and application of aspergillus oil suspending agent

Abstract

The invention belongs to the technical field of insect prevention preparations, and particularly relates to an aspergillus oil suspending agent for preventing and treating spodoptera frugiperda as well as a preparation method and application thereof. The aspergillus oil suspending agent containing the spore powder of the aspergillus with the preservation number of CGMCC No: 42111 has excellent insecticidal activity on spodoptera frugiperda, and has excellent stability, the stable period at the normal temperature reaches 12 months or above, and the aspergillus oil suspending agent is not layered after being frozen at the temperature of-5 DEG C for 24 hours. Besides, the aspergillus oil suspending agent is a dosage form which is high in activity, resistant to rain wash and suitable for various pesticide application scenes, aspergillus spores in the aspergillus oil suspending agent are high in adhesiveness and permeability to insect epidermis, and the prevention and control effect on the grassland spodoptera frugiperda can be enhanced.

Description

Technical Field

[0001] This invention belongs to the field of insect repellent formulation technology, specifically relating to an Aspergillus oil suspension for controlling fall armyworm, its preparation method, and its application. Background Technology

[0002] fall armyworm ( Spodoptera frugiperda Biological pests (BMPs) are a major global agricultural pest, primarily damaging food crops such as corn and rice. Their high reproductive capacity and rapid migration speed pose a serious threat to global agricultural production security. While traditional chemical pesticides can control pests in the short term, long-term use easily leads to increased pesticide resistance, pesticide residues polluting the environment, and harming human health, making them unsuitable for the demands of modern agriculture for green and sustainable development. With the increasing global emphasis on food safety and environmental protection, the development of highly efficient, low-toxicity, and environmentally friendly biological pesticides has become an inevitable trend in the construction of green pest control systems and a core approach to solving the problem of chemical pesticide overuse.

[0003] Microbial pesticides, due to their advantages such as good environmental compatibility, strong target specificity, and easy biodegradability, have shown great potential in the biological control of fall armyworm. Among them, entomopathogenic fungi are an important research direction. Aspergillus sp., as a class of highly efficient entomopathogenic fungi, has conidia that can penetrate the insect's body wall and enter the body cavity, killing the host through secreted enzymes and secondary metabolites. It has broad application prospects in the control of pests such as Lepidoptera and Coleoptera. However, the types of biological pesticides for fall armyworm are still relatively limited, and existing fungal preparations have significant technical bottlenecks: spores in water suspensions are easily degraded by ultraviolet light, with a field half-life of less than 5 days; oil suspensions are costly and have poor affinity with leaf surfaces, limiting large-scale application; and there is a technological gap in the field of wettable powders. Existing Aspergillus powders have low survival rates of dried spores (<40%), poor storage stability, and insufficient germination rates after rehydration, which seriously restricts the industrialization process of Aspergillus strains.

[0004] To address the aforementioned issues, particularly the core bottlenecks faced by Aspergillus strains in formulation development, such as the contradiction between drying inactivation and rehydration germination, and insufficient stability of wettable powders, there is an urgent need to develop a novel Aspergillus formulation that combines high storage stability, rapid wetting, and convenient field application through formulation innovation and technological optimization. This is of great significance for improving the biological control efficacy of fall armyworm, reducing application costs, and promoting the industrialization of microbial pesticides. Simultaneously, it can provide agricultural production with a low-cost, environmentally adaptable, and green control solution, meeting the diverse application needs of small-scale farmers in hilly areas. Summary of the Invention

[0005] Based on this, the present application provides a kind of aspergillus oil suspension agent containing the spore powder of aspergillus with preservation number CGMCC No:42111, the aspergillus oil suspension agent has excellent killing activity to Spodoptera frugiperda (Smith) Spodoptera frugiperda ) And excellent stability.

[0006] In order to achieve the above purpose, the present application can adopt the following technical scheme: The present application provides an aspergillus oil suspension agent for preventing and treating Spodoptera frugiperda, which comprises aspergillus spore powder, dispersant, emulsifier, thickening agent and oil carrier, and the preservation number of the aspergillus is CGMCC No:42111.

[0007] Preferably, the aspergillus oil suspension agent comprises, by mass percentage, 20-40% of aspergillus spore powder, 2-8% of dispersant, 3-10% of emulsifier, 0.5-3% of thickening agent and the balance of oil carrier.

[0008] Preferably, the aspergillus oil suspension agent has a particle size distribution of D50 of 5-8 μm and D90≤10 μm, and / or a suspension rate of ≥90%.

[0009] Preferably, the aspergillus oil suspension agent satisfies one or more combinations of the following conditions: (a1) the moisture content of the aspergillus spore powder is ≤5%; (b1) the particle size of the aspergillus spore powder is ≤50 μm; (c1) the viable spore count of the aspergillus spore powder is ≥1×10 9 CFU / g.

[0010] Preferably, the aspergillus oil suspension agent satisfies one or more combinations of the following conditions: (a2) the dispersant is selected from one or more combinations of sodium lignosulfonate, sodium polycarboxylate or alkylnaphthalene sulfonate; (b2) the emulsifier is selected from one or more combinations of Span-80, Tween-80 or fatty acid polyoxyethylene ester; (c2) the thickening agent is selected from one or more combinations of xanthan gum, bentonite or magnesium aluminum silicate; (d2) the oil carrier is selected from one or more combinations of soybean oil, methyl oleate or mineral oil.

[0011] Preferably, the aspergillus oil suspension agent further comprises an antifreeze agent and / or an ultraviolet absorber.

[0012] More preferably, in the aspergillus oil suspension agent, the antifreeze agent is selected from glycerol and / or ethylene glycol; and / or the ultraviolet absorber is selected from titanium dioxide and / or zinc oxide.

[0013] More preferably, in the above-mentioned Aspergillus oil suspension, the mass percentage of antifreeze is 1% to 5%; and / or the mass percentage of UV protectant is 0.1% to 1%.

[0014] Another aspect of the present invention provides a method for preparing the Aspergillus oil suspension of the present invention, the preparation method comprising: (1) Mix the dispersant, emulsifier, thickener and oil carrier and heat to obtain a uniform oil phase; (2) Add Aspergillus spore powder to the oil phase, grind, and adjust the pH to 6.5~7.5 to obtain Aspergillus oil suspension.

[0015] Another aspect of the present invention provides a method for controlling fall armyworm in crops, the method comprising: spraying the Aspergillus oil suspension of the present invention onto the leaves of crops.

[0016] Aspergillus in this invention ( Aspergillus sp. The preservation information for Aspergillus ( ) is as follows: Preservation Institution: China General Microbiological Culture Collection Center (CGMCC); Preservation Address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing; Preservation Date: June 26, 2025; Preservation Number: CGMCC No: 42111; Classification and Nomenclature: Aspergillus ( ) Aspergillus sp. ).

[0017] The beneficial effects of this invention include: the Aspergillus oil suspension containing Aspergillus spore powder with accession number CGMCC No: 42111 provided by this invention is effective against fall armyworm (… Spodoptera frugiperda It exhibits excellent insecticidal activity and stability, remaining stable for over 12 months at room temperature and showing no stratification after being frozen at -5°C for 24 hours. Furthermore, Aspergillus oil suspension is a highly active, rain-resistant formulation suitable for various application scenarios. The Aspergillus spores within it have strong adhesion and penetration to insect epidermis, enhancing its control effect against fall armyworm. Attached Figure Description

[0018] Figure 1 The images show preliminary morphological identification of Aspergillus; where A is a sporangiophore of Aspergillus spp., B is Aspergillus hyphae and spores, C is Aspergillus spores, and D is a sporangiophore of Aspergillus spp. producing conidia. Figure 2 Phylogenetic tree for molecular identification of Aspergillus strains. Detailed Implementation

[0019] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0020] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Singular expressions include plural expressions unless they have a distinct meaning in the context. As used herein, it should be understood that terms such as “comprising,” “having,” “including,” are intended to indicate the presence of features, numbers, operations, components, parts, elements, materials, or combinations thereof. The terminology of the invention is disclosed in the specification and is not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials, or combinations thereof may be present or added. As used herein, “ / ” may be interpreted as “and” or “or,” depending on the context.

[0021] In a first aspect, embodiments of the present invention provide an Aspergillus oil suspension for controlling fall armyworm. The Aspergillus oil suspension includes Aspergillus spore powder, dispersant, emulsifier, thickener and oil carrier. The Aspergillus preservation number is CGMCCNo:42111.

[0022] It should be noted that the Aspergillus ( ) in this invention Aspergillus sp. The preservation information for Aspergillus ( ) is as follows: Preservation Institution: China General Microbiological Culture Collection Center (CGMCC); Preservation Address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing; Preservation Date: June 26, 2025; Preservation Number: CGMCC No: 42111; Classification and Nomenclature: Aspergillus ( ) Aspergillus sp. ).

[0023] It should also be noted that the Aspergillus oil suspension containing Aspergillus spore powder with accession number CGMCC No: 42111 provided by this invention is effective against fall armyworm (…). Spodoptera frugiperda It exhibits excellent insecticidal activity and stability, remaining stable for over 12 months at room temperature and showing no stratification after being frozen at -5°C for 24 hours. Furthermore, Aspergillus oil suspension is a highly active, rain-resistant formulation suitable for various application scenarios. The Aspergillus spores within it have strong adhesion and penetration to insect epidermis, enhancing its control effect against fall armyworm.

[0024] It should also be noted that the functions of each component in the Aspergillus oil suspension of this invention are as follows: Aspergillus spore powder, as the active ingredient, can infect and kill the fall armyworm; the dispersant prevents spore aggregation and improves dispersibility; the thickener prevents stratification and regulates viscosity; the oil carrier acts as a solvent and spreading agent, enhancing epidermal permeability; and the emulsifier promotes spreading and adhesion, protects spore activity, and improves efficacy.

[0025] In some specific examples, the above-mentioned Aspergillus oil suspension agent comprises, in terms of mass percentage, 20-40% of Aspergillus spore powder, 2-8% of dispersing agent, 3-10% of emulsifying agent, 0.5-3% of thickening agent, and the balance of oil carrier.

[0026] It should be noted that the mass percentage of each component in the Aspergillus oil suspension agent in the present application can be prepared according to the above-mentioned mass percentage, for example, in terms of mass percentage, it can comprise 20-40% of Aspergillus spore powder (such as 25%, 30% or 35%, etc.), 2-8% of dispersing agent (such as 3%, 4%, 5%, 6% or 7%), 3-10% of emulsifying agent (such as 4%, 5%, 6%, 7%, 8% or 9%, etc.), 0.5-3% of thickening agent (such as 1%, 1.5%, 2% or 2.5%, etc.), and the balance of oil carrier.

[0027] In some specific examples, the particle size distribution of the above-mentioned Aspergillus oil suspension agent is that D50 is 5-8 μm, and D90≤10 μm.

[0028] It should be noted that the particle size of the Aspergillus oil suspension agent in the present application can be controlled to D50 of 5-8 μm (such as 5.5 μm, 6 μm, 6.5 μm or 7 μm, etc.), and D90≤10 μm. Controlling the particle size in this range is more conducive to the dispersion and suspension of the Aspergillus oil suspension agent.

[0029] In some specific examples, the above-mentioned Aspergillus oil suspension agent has a suspension rate of ≥90%.

[0030] It should be noted that the suspension rate of the Aspergillus oil suspension agent in the present application is preferably ≥90%, which is more conducive to the application of the Aspergillus oil suspension agent.

[0031] In some specific examples, the above-mentioned Aspergillus oil suspension agent satisfies one or a combination of the following conditions: (a1) the water content of the Aspergillus spore powder is ≤5%; specifically, the water content of the Aspergillus spore powder can be controlled to ≤5%, such as 2%, 3% or 4%, etc.; (b1) the particle size of the Aspergillus spore powder is ≤50 μm; specifically, the particle size of the Aspergillus spore powder is preferably ≤50 μm, which is more conducive to the dispersion of the Aspergillus spore powder in the mold oil suspension agent; (c1) the viable spore count of the Aspergillus spore powder is ≥1×10 9 CFU / g.

[0032] In some specific examples, the above-mentioned Aspergillus oil suspension agent satisfies one or a combination of the following conditions: (a2) the dispersing agent is selected from one or more combinations of sodium lignosulfonate, sodium polycarboxylate or alkylnaphthalene sulfonate; in particular, the dispersing agent in the present application is well known in the art, and one or more combinations of sodium lignosulfonate, sodium polycarboxylate or alkylnaphthalene sulfonate can be preferred in the present application, which has better dispersing effect in the aspergillus oil suspension agent in the present application; (b2) the emulsifying agent is selected from one or more combinations of Span-80, Tween-80 or fatty acid polyoxyethylene ester; in particular, the emulsifying agent in the present application is well known in the art, and one or more combinations of Span-80, Tween-80 or fatty acid polyoxyethylene ester can be preferred in the present application, which has better emulsifying effect in the aspergillus oil suspension agent in the present application; (c2) the thickening agent is selected from one or more combinations of xanthan gum, bentonite or magnesium aluminum silicate; in particular, the thickening agent in the present application is well known in the art, and one or more combinations of xanthan gum, bentonite or magnesium aluminum silicate can be preferred in the present application, which has better thickening effect in the aspergillus oil suspension agent in the present application; (d2) the oil carrier is selected from one or more combinations of soybean oil, methyl oleate or mineral oil; in particular, the oil carrier in the present application is well known in the art, and one or more combinations of soybean oil, methyl oleate or mineral oil can be preferred in the present application.

[0033] In some specific examples, the aspergillus oil suspension agent described above further comprises an anti-freezing agent and / or an ultraviolet protection agent.

[0034] It should be noted that the aspergillus oil suspension agent in the present application can also add an anti-freezing agent and / or an ultraviolet protection agent, which can improve the anti-freezing and ultraviolet resistance of the aspergillus oil suspension agent.

[0035] In some specific examples, the aspergillus oil suspension agent described above, the anti-freezing agent is selected from glycerol and / or ethylene glycol; and / or the ultraviolet protection agent is selected from titanium dioxide and / or zinc oxide.

[0036] It should be noted that the anti-freezing agent and the ultraviolet protection agent in the present application are well known in the art, and the above-mentioned anti-freezing agent and ultraviolet protection agent are preferred.

[0037] In some specific examples, the aspergillus oil suspension agent described above, the mass percentage of the anti-freezing agent is 1% to 5%; and / or the mass percentage of the ultraviolet protection agent is 0.1% to 1%.

[0038] It should be noted that the mass percentage of the anti-freezing agent in the present application can be 1% to 5%, for example, 2%, 3% or 4%, etc.; in addition, the mass percentage of the ultraviolet protection agent can be 0.1% to 1%, for example, 0.3%, 0.5% or 0.7%, etc.

[0039] In a second aspect, the present application provides a preparation method of the aspergillus oil suspension in the present application, which comprises the following steps: (1) mixing and heating a dispersing agent, an emulsifier, a thickening agent and an oil carrier to obtain a uniform oil phase; (2) adding aspergillus spore powder into the oil phase, grinding, and adjusting the pH to 6.5-7.5 to obtain the aspergillus oil suspension.

[0040] It should be noted that the preparation method of the aspergillus oil suspension in the present application only needs to mix, crush and grind the components, and the preparation method is simple. In addition, in step (2), the pH is adjusted to 6.5-7.5 after grinding, and the pH of 6.5-7.5 is the optimum pH for the germination of aspergillus spores.

[0041] In a third aspect, the present application provides a method for preventing and treating Spodoptera frugiperda in crops, which comprises spraying the aspergillus oil suspension in the present application on the leaf surface of crops.

[0042] It should be noted that the aspergillus oil suspension in the present application can be used to prevent and treat Spodoptera frugiperda by spraying it on the leaf surface of crops.

[0043] In order to better understand the present application, the content of the present application will be further illustrated below in combination with specific examples, but the content of the present application is not limited to the following examples.

[0044] In the following examples, the preservation number of the aspergillus used is CGMCC No: 42111, and the isolation, purification and identification process of the aspergillus strain is provided as follows: (1) Isolation and purification of the strain The target fungus is isolated from the dead red imported fire ant body wall covered with mycelium, which specifically comprises: slowly soaking the red imported fire ant body wall with sterile water, then inoculating on an SDA plate (containing SDA medium, the same below), and culturing in a 28°C constant temperature incubator; after mycelium grows on the surface of the tissue block, it is timely transferred to a new SDA plate and cultured in an inverted culture in a 28°C incubator, and the purification is repeated for 3 times, then inoculated on an SDA test tube (SDA medium) slant, and after the colony covers the slant, it is stored in a-80°C refrigerator. (2) Identification of the strain (2-1) Morphological identification The isolated and purified strain was inoculated on SDA plate and cultured in a constant temperature incubator at 28°C. The color, texture, size, height, surface texture, edge, exudate, etc. of the front and back of the colony were observed daily and photographed. A small amount of spores was picked up with an inoculation needle and inoculated on SDA plate. When the sporulation was mature, a slide was prepared. A small piece of transparent tape with fine texture was clamped with tweezers, and the tape was gently and slowly adhered from the edge to the center of the colony. Then, 95% alcohol was used for fixation and immersion in cotton lan dye. The transparent tape with spore-producing structure was placed with the face up, and a cover glass was gently placed after 3 min to avoid air bubbles. The field of view was found under low power, cedar oil or paraffin oil was added, and the structure characteristics of conidial phialide, spore cell and spore were observed under an oil immersion lens. The camera was used to take pictures at 1000 times, and then the pictures were synthesized and arranged, as shown in Figure 1 . Figure 1 It was shown that the strain presented a white milk color on the front of the colony, a tree branch bifurcation, a light yellow back, multiple irregular wheel marks and irregular folds of the colony. In addition, the conidiophores were of different lengths, the wall was smooth, the top of the conidiophore was swollen to form a nearly spherical top cyst, and the conidiophore was attached to a nearly spherical conidium.

[0045] (2-2) Molecular identification Extraction of strain DNA: After activation and culture of the strain, about 0.1 g of mycelium was picked into a sterile 1.5 mL centrifuge tube, frozen in liquid nitrogen and ground into powder. The Genewiz Ezup column type fungal genomic DNA extraction kit (Genewiz Biotech Co., Ltd., Shanghai) was used to extract the total DNA of the fungus. After extraction, the total DNA was stored at -20°C for standby.

[0046] Amplification and determination of rDNA ITS sequence: The extracted total DNA of the fungus was used as a template, and PCR amplification was performed using fungal 18rDNA universal primers ITS1 (base sequence 5'-TCCGTAGGTGAACCTGCGG-3') and ITS4 (base sequence 5'-TCCTCCGCTTATTGATATGC-3'). The PCR reaction system (50 μL) was: ddH2O 20 μL, Mix 25 μL, forward primer 1.5 μL, reverse primer 1.5 μL, DNA 2 μL. The reaction conditions were: 94°C pre-denaturation for 3 min, then 35 cycles of 94°C denaturation for 30 s, 56°C annealing for 40 s, and 72°C extension for 50 s, and finally 72°C extension for 10 min.

[0047] Gel electrophoresis detection: PCR products were detected by 1% agarose gel electrophoresis and then sent to Kunming Sophon Biotechnology Co., Ltd. for direct sequencing; then molecular phylogenetic analysis: after bidirectional sequencing and sequence splicing, BLAST comparison was performed in the NCBI database, and the sequence of the strain with higher homology in Gen Bank was selected. MEGA 5.0 and ClustalX 1.83 software were used for multiple sequence alignment analysis, and a phylogenetic tree was constructed, with 1000 times of repetition for Bootstrap to verify its credibility. The gene sequence obtained by purifying, recovering and sequencing the PCR product of the strain (Table 1) was used to construct a Neighbor Joining Tree (see Figure 2 ). The obtained DNA sequence was subjected to Blast comparison on NCBI. After comparison, it was found that the strain had high similarity with Aspergillus, and the strain and Aspergillus related strains were clustered into one branch, while the genetic distance with the outgroup was far; combined with the morphological identification of the strain, it could be determined that the strain was Aspergillus Aspergillus sp. ).

[0048] Table 1 Sequence of PCR product of the strain , In addition, the mycelial growth and sporulation characteristics of the Aspergillus strain with the preservation number of CGMCC No: 42111 are as follows: the slant strain of the Aspergillus strain was taken out and activated, inoculated on SDA plates, and cultured in a constant temperature incubator for 10 days, and then the conidiospores on the surface of the culture medium were scraped off and collected by filtering with sterile water containing 0.1% Tween 80, and prepared into a conidiospore suspension of 1×10 7 spores / mL; 1 mL of the conidiospore suspension was dropped on the center of the SDA plate, evenly spread, and then sealed in a constant temperature incubator for culture, and the diameters of the colonies were recorded every day for 10 days, with 3 repeats; after 10 days, the conidiospores were filtered with sterile water containing 0.1% Tween 80, and the sporulation amount was determined using a modified Neubauer counting chamber. The results showed that the colony diameter of the Aspergillus strain reached (85±2) mm after 7 days of culture, and the sporulation amount on SDA after 10 days of culture was 1.2×10 7 spores / mL, as shown in Table 2 below.

[0049] Table 2 Colony growth rate and sporulation amount of Aspergillus strain , In the following examples, the viable spore content is measured by plate counting method, the particle size distribution is tested by Mastersizer series laser particle size analyzer, the suspension rate is tested by measuring cylinder method, the emulsion stability is tested by centrifugation method, and the room temperature storage stability is tested by accelerated aging test.

[0050] Example Example 1

[0051] (1) Aspergillus spore powder treatment: Aspergillus strain with preservation number CGMCC No: 42111 was fermented in a liquid fermentation tank, spores were collected by centrifugation with a disc centrifuge, vacuum freeze-dried to a water content of 5%, and ground to a particle size of ≤50 μm, with a viable spore content of 1.1×10 9 CFU / g; (2) Oil phase preparation: 30 g of Aspergillus spore powder, 5 g of sodium lignosulfonate, 6 g of Span-80, 1 g of xanthan gum, and 58 g of soybean oil were added to a reaction kettle, stirred at 60°C for 30 minutes until completely dissolved, and a uniform oil phase was formed; (3) Sand mill dispersion: The spore powder was slowly added to the oil phase, and the sand mill (zirconium bead diameter 1.2 mm, mass 29.2 kg) was started (mass ratio of oil to spore powder 4:1), and ground for 3 hours to a particle size D90≤10 μm; (4) Finished product formulation: The pH was adjusted to 6.5-7.5 with dilute hydrochloric acid or sodium hydroxide to obtain Aspergillus oil suspension concentrate.

[0052] The Aspergillus oil suspension concentrate prepared in Example 1 had a particle size D50=6.2 μm, a suspension rate of 92%, qualified emulsion stability, and a viable spore survival rate of 88% after 6 months of storage at room temperature.

[0053] Example 2 Example 2 was substantially the same as Example 1, except that the raw materials were different, and the Aspergillus oil suspension concentrate was prepared according to Example 1. The raw materials for Example 2 were: Aspergillus spore powder 26 g, sodium polycarboxylate 4 g, Tween-80 8 g, bentonite 2 g, methyl oleate 59 g, and titanium dioxide 1 g (added in step (4)).

[0054] The viable spore survival rate of the Aspergillus oil suspension concentrate prepared in Example 2 was 75% after 4 hours of UV irradiation (52% for the Aspergillus oil suspension concentrate prepared in Example 1), and the residual period was extended to 14 days through field trials.

[0055] Example 3 Example 3 was substantially the same as Example 1, except that the raw materials were different, and the Aspergillus oil suspension concentrate was prepared according to Example 1. The raw materials for Example 3 were: Aspergillus spore powder 35 g, alkyl naphthalene sulfonate 6 g, fatty acid polyoxyethylene ester 7 g, magnesium aluminum silicate 1.5 g, mineral oil 49 g, and glycerol 1.5 g.

[0056] The Aspergillus oil suspension concentrate prepared in Example 3 had no delamination after being frozen at -5°C for 24 hours, and the suspension rate was 89% after thawing, making it suitable for use in early spring in the north.

[0057] Example 4 Example 4 is substantially the same as Example 1, except that the raw materials are different, and the rest is the same as Example 1, to prepare an Aspergillus oil suspension agent; wherein the raw materials of Example 4 are: Aspergillus spore powder 32 g, alkyl naphthalene sulfonate 4 g, triethanolamine oleate 9 g, magnesium aluminum silicate 1.5 g, methyl oleate 52 g, zinc oxide 0.5 g (added in step (4)).

[0058] The contact angle of the Aspergillus oil suspension agent prepared in Example 4 on the cuticle of Spodoptera exigua larvae is only 18° (32° for ordinary formulations), significantly improving the infection efficiency.

[0059] Example 5 Example 5 is substantially the same as Example 1, except that the raw materials are different, and the rest is the same as Example 1, to prepare an Aspergillus oil suspension agent; wherein the raw materials of Example 5 are: Aspergillus spore powder 28 g, sodium lignosulfonate 5 g, fatty acid polyoxyethylene ester 10 g, bentonite 2 g, mineral oil (high viscosity type) 54 g, polyvinyl alcohol (PVA) 1 g.

[0060] The spore retention rate of the Aspergillus oil suspension agent prepared in Example 5 reaches 78% (55% for the Aspergillus oil suspension agent prepared in Example 1) within 2 hours after application and before rainfall (rainfall amount 30 mm); In addition, the Aspergillus oil suspension agent prepared in Example 5 is used for field experiments in corn fields in the rainy areas of South China, and the 7-day mortality rate of Spodoptera exigua reaches 84%, which is 6% higher than that of the Aspergillus oil suspension agent prepared in Example 1; that is, the Aspergillus oil suspension agent prepared in Example 5 is suitable for agricultural areas in the south where it rains frequently, or scenarios that require simultaneous operation with irrigation.

[0061] Performance test The indoor toxicity of the Aspergillus oil suspension agent prepared in Example 1 on Spodoptera exigua is determined by leaf immersion method, which specifically includes: collecting fresh corn leaves without toxicity, and making leaf discs of uniform size (such as 2 cm in diameter) with a puncher; diluting the oil suspension agent with sterile water to different concentration gradients; immersing each concentration-treated leaf disc in the liquid for 15 seconds, and then taking it out and absorbing the excess liquid with filter paper; the negative control leaf blades are immersed in sterile water; placing the treated leaf discs in a rearing box, and putting 1 three-age larva into each box; 80 larvae are treated at each concentration (usually 10 repeats, 8 larvae per repeat); placing the rearing box in a constant temperature incubator (such as 25±1°C, light cycle L:D=14:10, RH>70%); replacing the fresh treated leaf discs every day until the control group pupates or the test is completed; investigating the larval mortality after treatment (death standard: touching the body with a soft brush, no reaction or body decay is considered dead), and recording the number of dead insects. Using professional statistical software (such as SPSS, POLO, DPS or R language), the concentration logarithm (X) and the mortality probability value (Y) are analyzed by Probit analysis, and the half lethal concentration (LC50 ) and the median lethal time (LT 50 ). The results show that the Aspergillus oil suspension prepared in Example 1 has an LC 50 of 2.3 x 10 7 spores / mL and an LT 50 of 3.8 days.

[0062] In addition, the insecticidal activity of the Aspergillus oil suspension prepared in Examples 1 to 5 against Spodoptera exigua was tested, and the test was performed as follows: three groups of parallel tests were set up, and a randomized block design was used; three doses of the Aspergillus oil suspension were set up for high, medium and low treatment, and one blank control (water) was set up. Each treatment was set up at least 4 times. The area of each plot was generally not less than 30 m 2 . Guard rows were set up between plots to avoid interference caused by drift of the pesticide; a conventional knapsack sprayer (fan-shaped nozzle) was used to uniformly spray the foliage, and the amount of pesticide liquid used per mu was 50 L; the pesticide was applied in sunny and windless or light wind weather to avoid application at noon in high temperature or before rain; one day before application, 20 corn plants were investigated in each plot using the "Z" shaped five-point sampling method, the number of 3rd instar larvae on each plant was recorded as the initial pest population, and the number of surviving pests after application was investigated; the investigation focused on checking the hiding places of pests such as heart leaves, tassels and ear parts; the pest population reduction rate (%) = [(number of pests before application-number of pests after application) / number of pests before application] x 100; the control effect (%) = [(population reduction rate in the treatment area-population reduction rate in the control area) / (100-population reduction rate in the control area)] x 100; the test results are shown in Table 3.

[0063] Table 3 Insecticidal activity of the Aspergillus oil suspension prepared in Examples 1 to 5 against Spodoptera exigua , Note: The reduction rate refers to the percentage of the reduction in the number of pests after treatment. On the basis of the pest population reduction rate, the natural change in the control area is used to eliminate the influence of natural factors, and the final control effect caused purely by the pesticide is obtained.

[0064] As can be seen from Table 3, the Aspergillus oil suspension prepared in Examples 1 to 5 has high insecticidal activity against Spodoptera exigua.

[0065] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and they should all be covered in the scope of the claims of the present application.

Claims

1. An Aspergillus oil suspension for controlling fall armyworm, characterized in that, Aspergillus oil suspensions include Aspergillus spore powder, dispersants, emulsifiers, thickeners, and oil carriers. The preservation number of Aspergillus is CGMCC No: 42111.

2. The Aspergillus oil suspension according to claim 1, characterized in that, Aspergillus oil suspension, by mass percentage, includes: 20%–40% Aspergillus spore powder, 2%–8% dispersant, 3%–10% emulsifier, 0.5%–3% thickener, and the balance being an oil carrier.

3. The Aspergillus oil suspension according to claim 1 or 2, characterized in that, The particle size distribution of Aspergillus oil suspension is: D50 5μm~8μm, D90≤10μm; and / or The suspension rate of Aspergillus oil suspension is ≥90%.

4. The Aspergillus oil suspension according to claim 1 or 2, characterized in that, Aspergillus oil suspension meets one or more of the following conditions: (a1) The moisture content of Aspergillus spore powder is ≤5%; (b1) The particle size of Aspergillus spore powder is ≤50μm; (c1) The number of viable spores in Aspergillus spore powder is ≥1×10 9 CFU / g.

5. The Aspergillus oil suspension according to claim 1 or 2, characterized in that, Aspergillus oil suspension meets one or more of the following conditions: (a2) The dispersant is selected from one or more combinations of sodium lignosulfonate, sodium polycarboxylate, or alkyl naphthalene sulfonate; (b2) The emulsifier is selected from one or more combinations of Span-80, Tween-80 or fatty acid polyoxyethylene esters; (c2) The thickener is selected from one or more combinations of xanthan gum, bentonite or magnesium aluminum silicate; (d2) The oil carrier is selected from one or more combinations of soybean oil, methyl oleate or mineral oil.

6. The Aspergillus oil suspension according to claim 1 or 2, characterized in that, Aspergillus oil suspensions also include antifreeze agents and / or ultraviolet absorbers.

7. The Aspergillus oil suspension according to claim 6, characterized in that, Antifreeze agents are selected from glycerin and / or ethylene glycol; and / or The UV protectant is selected from titanium dioxide and / or zinc oxide.

8. The Aspergillus oil suspension according to claim 7, characterized in that, The antifreeze has a mass percentage of 1% to 5%; and / or The mass percentage of the UV protectant is 0.1% to 1%.

9. The method for preparing the Aspergillus oil suspension according to any one of claims 1 to 8, characterized in that, Preparation methods include: (1) Mix the dispersant, emulsifier, thickener and oil carrier and heat to obtain a uniform oil phase; (2) Add Aspergillus spore powder to the oil phase, grind, and adjust the pH to 6.5~7.5 to obtain Aspergillus oil suspension.

10. A method for controlling fall armyworm in crops, characterized in that, The methods include: The Aspergillus oil suspension according to any one of claims 1 to 8 is sprayed on the leaves of crops.

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