A slow-release nano-suspension agent, a preparation method and application thereof

Abstract

The application provides a slow-release nano-suspension agent and a preparation method and application thereof, and belongs to the technical field of pesticide preparations. The slow-release nano-suspension agent is prepared from the following raw materials in percentage by weight: pyrethroid 1-20%, wetting agent 3-8%, dispersing agent 2-7%, antifreezing agent 4-6%, defoaming agent 0.05-1%, preservative 0.01-1%, pH regulator 0.01-0.4%, and water is added to 100%; the wetting agent is polyvinyl alcohol and sodium lignosulfonate, and the mass ratio of the polyvinyl alcohol and the sodium lignosulfonate is 1-3:3. The slow-release nano-suspension agent can reduce the decomposition of the raw material, gradually releases through the slow destruction of hydrogen bonds, and prolongs the drug efficacy. The slow-release nano-suspension agent is stable in the tests of heat storage, cold storage and long-term storage, and the slow-release nano-suspension agent has obvious prevention effect and the effective period is prolonged by 1-2 times compared with the traditional suspension agent.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of agricultural preparation, and particularly relates to a slow-release nano-suspension agent and a preparation method and application thereof. BACKGROUND

[0002] Pyrethroid insecticides are biomimetic synthetic insecticides, which are synthesized esters derived by changing the chemical structure of natural pyrethroids. They have stronger insecticidal toxicity than other pyrethroid insecticides, can quickly interfere with the function of neurons after entering the insect body, and can effectively protect various crops such as cotton and fruit trees from being eaten by pests with piercing-sucking mouthparts and various pests such as mites. Due to the characteristics of broad-spectrum, high efficiency, easy degradation and low toxicity, pyrethroid insecticides are widely used in the process of planting field crops and vegetables. The pyrethroid insecticides prepared by traditional preparation methods are prone to aggregation and solidification, which leads to poor storage and poor control effect on crop pests, and it is difficult to meet the preparation needs of pesticides for controlling crop pests. Moreover, they are easy to lose effectiveness under the action of external environment, such as sunlight, soil pH, etc., and have a short duration, thereby reducing the control effect of the pesticide. SUMMARY

[0003] In view of this, the purpose of the present application is to provide a slow-release nano-suspension agent and a preparation method and application thereof. The slow-release nano-suspension agent prolongs the duration of controlling pests and significantly improves the efficiency of controlling pests.

[0004] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0005] The present application provides a slow-release nano-suspension agent, which is prepared from the following raw materials in weight percentage: 1-20% of pyrethroid insecticide, 3-8% of wetting agent, 2-7% of dispersing agent, 4-6% of antifreeze, 0.05-1% of defoaming agent, 0.01-1% of preservative, 0.01-0.4% of pH regulator, and water to make up to 100%.

[0006] The wetting agent is polyvinyl alcohol and sodium lignosulfonate, and the mass ratio of polyvinyl alcohol and sodium lignosulfonate is 1-3:3.

[0007] Preferably, the particle size of the slow-release nano-suspension agent is 200-500 nm.

[0008] Preferably, the pyrethroid insecticide includes one or more of lambda-cyhalothrin, ethofenprox, benzotrac, deltamethrin, cypermethrin, high-efficiency cypermethrin, cis-cypermethrin, allethrin, fenvalerate, cyhalothrin, fluoroethane, fluvalinate, fluvalinate, allethrin, methylocyanophyll, chlorofluorocyanophyll and bifenthrin.

[0009] Preferably, the dispersant comprises one or both of a phosphate ester and a block polyether.

[0010] Preferably, the phosphate ester comprises one of 33SC, 500LQ, 2210 and 1020; the block polyether comprises one of 5500 and 5050PB.

[0011] Preferably, the antifoaming agent comprises one or more of an ester-ether type compound, C8-C 10 one or more of a fatty alcohol, an organic silicone and a silicone oil; the preservative comprises one or more of formaldehyde, sodium benzoate and potassium sorbate; the pH regulator comprises one or more of phosphoric acid, lactic acid and citric acid; the pH value of the slow-release nano-suspension agent is 5.0-7.0; and the antifreeze agent is ethylene glycol.

[0012] The present application provides a preparation method of the slow-release nano-suspension agent, comprising the following steps:

[0013] (1) mixing the pyrethroid original drug, the dispersant, the wetting agent, the antifreeze agent, the preservative and water to obtain a mixed slurry;

[0014] (2) sand milling the mixed slurry, and adding the antifoaming agent during the milling process to obtain a sand-milled slurry;

[0015] (3) mixing the sand-milled slurry with the pH regulator to obtain the slow-release nano-suspension agent.

[0016] Preferably, the sand milling temperature is 20-30℃, and the sand milling is to a particle size of 200-500nm.

[0017] The present application provides an application of the slow-release nano-suspension agent or the preparation method in the prevention and control of pests or the preparation of insecticides.

[0018] Preferably, the pests comprise one or more of aphids, cotton bollworms, beet armyworms, tea green leafhoppers and black ground beetles.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The application provides a slow-release nano-suspension agent and a preparation method and application thereof, and adopts polyvinyl alcohol and sodium lignosulfonate as wetting agents, in the sanding process, the hydrophilic end of the sodium lignosulfonate can form 3D hydrogen bonds with water and polyvinyl alcohol to wrap the original pesticide particles to self-assemble nano original pesticide particles, meanwhile, the hydrophobic end of the wetting agent can combine with the wax layer of the insect cuticle to make it quickly enter the insect body, and also form a water-locking film on the leaf surface to reduce the decomposition of the original pesticide, and gradually release through the slow destruction of the hydrogen bonds, so as to achieve the purpose of prolonging the drug effect. The slow-release nano-suspension agent is stable in performance, obvious in prevention effect and 1-2 times longer in effective period than the traditional suspension agent through the heat storage, cold storage and long-term storage stability tests. DETAILED DESCRIPTION

[0021] The application provides a slow-release nano-suspension agent, which is prepared from the following raw materials in percentage by weight: pyrethroid original pesticide 1-20%, wetting agent 3-8%, dispersing agent 2-7%, antifreezing agent 4-6%, defoaming agent 0.05-1%, preservative 0.01-1%, pH regulator 0.01-0.4%, and water is added to 100%.

[0022] The wetting agent is polyvinyl alcohol and sodium lignosulfonate, and the mass ratio of the polyvinyl alcohol and the sodium lignosulfonate is 1-3:3.

[0023] The slow-release nano-suspension agent is preferably prepared from the following raw materials in percentage by weight: pyrethroid original pesticide 2-15%, wetting agent 4-6%, dispersing agent 3-6%, antifreezing agent 4-6%, defoaming agent 0.2-0.6%, preservative 0.03-0.5%, pH regulator 0.1-0.3%, and water is added to 100%.

[0024] The wetting agent is polyvinyl alcohol and sodium lignosulfonate, and the mass ratio of the polyvinyl alcohol and the sodium lignosulfonate is 1-3:3.

[0025] In this invention, the preferred mass ratio of polyvinyl alcohol to sodium lignosulfonate is 1.5–2.5:3, more preferably 2:3. The wetting agent of this invention is a hydrogel, a highly hydrophilic three-dimensional network structure gel that can serve as a drug carrier. During the sand milling process, polyvinyl alcohol and sodium lignosulfonate are added to the pesticide formulation as wetting agents. The abundant amphiphilic functional groups of sodium lignosulfonate self-assemble into micro / nano particles in aqueous solution. Simultaneously, the hydrophilic functional groups such as sulfonic acid groups, carboxyl groups, and hydroxyl groups exposed on the outer surface can form abundant hydrogen bonds with the polyvinyl alcohol matrix and water, constructing a 3D hydrogen bond network to encapsulate the active ingredient and form active ingredient nanoparticles. After the pesticide acts on the surface of the pest, the hydrophobic end of the polyvinyl alcohol-modified sodium lignosulfonate combines with the waxy layer on the pest's surface to form a thin film, promoting drug absorption. The pesticide sprayed on plant leaves achieves slow release through the gradual disruption of hydrogen bonds, thus prolonging the efficacy, increasing the duration of drug effectiveness, reducing the number of applications, and improving the control effect.

[0026] In this invention, for the pesticide active ingredient, the smaller the particle size in the formulation, the more pesticide active ingredient particles are dispersed per unit area of ​​the target, the larger the specific surface area, and the larger the contact area with the target organism, thus achieving better efficacy. The nanoscale slow-release nano-suspension of this invention has higher efficacy and requires less dosage than traditional suspensions with micron-sized (1-5 μm) particles, aligning with the national policy of reducing application and increasing efficiency, and is of great significance to food safety. The particle size of the slow-release nano-suspension is preferably 200-500 nm.

[0027] In this invention, the pyrethroid technical grade includes one or more of the following: lambda-cyhalothrin, fenpropathrin, benzyl chlorpyrifos, deltamethrin, cypermethrin, lambda-cyhalothrin, cis-cypermethrin, cypermethrin, fenvalerate, cypermethrin, cypermethrin, deltamethrin, fenpropathrin, cypermethrin, cypermethrin, and bifenthrin. The dispersant includes one or both of phosphate esters and block polyethers. More preferably, the phosphate ester includes one of 33SC, 500LQ, 2210, and 1020; the block polyether includes one of 5500 and 5050PB. The defoamer includes ester-ether compounds, C8-C... 10 The preservative includes one or more of fatty alcohols, organosilicones, and silicone oils; the preservative includes one or more of formaldehyde, sodium benzoate, and potassium sorbate; the pH adjuster includes one or more of phosphoric acid, lactic acid, and citric acid; and the pH value of the sustained-release nano-suspension is 5.0 to 7.0.

[0028] This invention provides a method for preparing the above-mentioned sustained-release nano-suspension, comprising the following steps:

[0029] (1) The pyrethroid technical, dispersant, wetting agent, antifreeze, preservative and water are mixed to obtain a mixed slurry;

[0030] (2) The mixed slurry is milled, and the defoamer is added during the milling process to obtain the milled slurry;

[0031] (3) The slurry after sand milling is mixed with the pH adjuster to obtain a slow-release nano suspension.

[0032] In this invention, the pyrethroid technical, dispersant, wetting agent, antifreeze, preservative, and water are mixed to obtain a slurry. The mixing can be shear mixing to ensure uniform mixing. After obtaining the slurry, it is milled, with the defoamer added during the milling process, to obtain a milled slurry. The milling temperature is preferably 20–30°C, more preferably 22–28°C, and the milling is performed to a particle size preferably of 200–500 nm. The milled slurry is then mixed with the pH adjuster to obtain a sustained-release nano-suspension with a pH value of 5.0–7.0.

[0033] This invention provides an application of the above-mentioned slow-release nano-suspension or preparation method in the prevention and control of pests or the preparation of insecticides.

[0034] In this invention, the slow-release nano-suspension or its preparation method can be used to extend the duration of pest control and improve pest killing efficiency, thereby reducing the amount of pesticide applied. The preferred pests include one or more of aphids, bollworms, beet armyworms, tea green leafhoppers, and cutworms.

[0035] Compared with traditional suspending agents, the slow-release nano-suspending agent of the present invention, even without the addition of thickeners, shows through stability tests that it has a uniform appearance, no crystal precipitation under temperature changes, good pourability, and good cold and hot storage stability.

[0036] In this invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0037] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0038] In the following embodiments, the phosphate ester (33SC) was purchased from Xingfei Chemical (Shanghai) Co., Ltd.; the phosphate ester (500LQ) was purchased from Nanjing Jierun Technology Co., Ltd.; the phosphate ester (2210) was purchased from Indorama Corporation, Indonesia; the phosphate ester (1020) was purchased from Wuxi Yijingfeng Technology Co., Ltd.; the block polyether (5500) was purchased from Indorama Corporation, Indonesia; the block polyether (5050PB) was purchased from Jieshi Chemical (Shanghai) Co., Ltd.; and the sodium lignosulfonate was purchased from Shenzhen Zhong Shenghe Biotechnology Co., Ltd. Among them, 33SC is the product number of phosphate esters purchased from Xingfei Chemical (Shanghai) Co., Ltd.; 500LQ is the product number of phosphate esters purchased from Nanjing Jierun Technology Co., Ltd.; 2210 is the product number of phosphate esters purchased from Indorama Corporation, Indonesia; 1020 is the product number of phosphate esters purchased from Wuxi Yijingfeng Technology Co., Ltd.; 5500 is the product number of block polyethers purchased from Indorama Corporation, Indonesia; and 5050PB is the product number of block polyethers purchased from Jieshi Chemical (Shanghai) Co., Ltd.

[0039] Example 1

[0040] A slow-release nano-suspension, based on 100 parts by weight of its raw materials, comprises the following components: 2.5% lambda-cyhalothrin, 2% polyvinyl alcohol, 3% sodium lignosulfonate, 3% phosphate ester (33SC), 4% ethylene glycol, 0.4% organosilicone, 0.1% formaldehyde, and 0.2% phosphoric acid, with water to make up to 100%.

[0041] The specific steps for preparing the sustained-release nano-suspension are as follows:

[0042] a. Weigh out the above-mentioned amounts of high-efficiency cyhalothrin, phosphate ester (33SC), polyvinyl alcohol, sodium lignosulfonate, ethylene glycol, formaldehyde and water respectively, and put them into a mixing tank for shearing and mixing until uniform, to obtain the mixed slurry;

[0043] b. Under the condition of 20-30℃, the slurry mixed in step a is fed into a pin mill for grinding, and the above-mentioned weight amount of organosilicone is added while grinding. The slurry is ground until the particle size is 200-500nm to obtain the ground slurry.

[0044] c. Add the slurry obtained from sand milling in step b to the above-mentioned weight amount of phosphoric acid to adjust the pH value to the range of 5.0 to 7.0, thereby obtaining 2.5% high-efficiency cyhalothrin nano-suspension agent.

[0045] Example 2

[0046] A slow-release nano-suspension agent, based on 100 parts by weight of its raw materials, comprises the following components in weight percentage: 5% high-efficiency cypermethrin, 2% polyvinyl alcohol, 3% sodium lignosulfonate, 2% phosphate ester (2210), 1% block polyether (5500), 4% ethylene glycol, 0.4% organosilicone, 0.1% formaldehyde, 0.2% phosphoric acid, and water to make up to 100%.

[0047] The specific steps for preparing the sustained-release nano-suspension are as follows:

[0048] a. Weigh out the above-mentioned amounts of high-efficiency cyhalothrin, phosphate ester (2210), block polyether (5500), polyvinyl alcohol, sodium lignosulfonate, ethylene glycol, formaldehyde and water respectively, and put them into a mixing tank for shearing and mixing until uniform, to obtain the mixed slurry.

[0049] b. Under the condition of 20-30℃, the slurry mixed in step a is fed into a pin mill for grinding, and the above-mentioned weight amount of organosilicone is added while grinding. The slurry is ground until the particle size is 200-500nm to obtain the ground slurry.

[0050] c. Add the above-mentioned weight amount of phosphoric acid to the slurry obtained in step b after sand milling to adjust the pH value to the range of 5.0 to 7.0, thereby obtaining 5% high-efficiency cyhalothrin nano-suspension.

[0051] Example 3

[0052] A slow-release nano-suspension, based on 100 parts by weight of its raw materials, comprises the following components in weight percentage: deltamethrin 10%, polyvinyl alcohol 2%, sodium lignosulfonate 3%, phosphate ester (2210) 3%, ethylene glycol 4%, organosilicon 0.4%, formaldehyde 0.1%, phosphoric acid 0.3%, and water to make up to 100%.

[0053] The specific steps for preparing the sustained-release nano-suspension are as follows:

[0054] a. Weigh out the above-mentioned amounts of deltamethrin, phosphate ester (2210), polyvinyl alcohol, sodium lignosulfonate, ethylene glycol, formaldehyde and water respectively, and put them into a mixing tank for shearing and mixing until uniform, to obtain the mixed slurry;

[0055] b. Under the condition of 20-30℃, the slurry mixed in step a is fed into a pin mill for grinding, and the above-mentioned weight amount of organosilicone is added while grinding. The slurry is ground until the particle size is 200-500nm to obtain the ground slurry.

[0056] c. Add the slurry obtained from sand milling in step b to the above-mentioned weight amount of phosphoric acid to adjust the pH value to the range of 5.0 to 7.0, thereby obtaining 10% deltamethrin nano-suspension.

[0057] Example 4

[0058] A slow-release nano-suspension, based on 100 parts by weight of its raw materials, comprises the following components in weight percentage: 20% bifenthrin, 2% polyvinyl alcohol, 3% sodium lignosulfonate, 2% block polyether (5050PB), 4% ethylene glycol, 0.4% organosilicone, 0.1% formaldehyde, 0.25% phosphoric acid, and water to make up to 100%.

[0059] The specific steps for preparing the sustained-release nano-suspension are as follows:

[0060] a. Weigh out the above-mentioned amounts of bifenthrin, block polyether (5050PB), polyvinyl alcohol, sodium lignosulfonate, ethylene glycol, formaldehyde and water respectively, and put them into a mixing tank for shearing and mixing until uniform, to obtain the mixed slurry.

[0061] b. Under the condition of 20-30℃, the slurry mixed in step a is fed into a pin mill for grinding, and the above-mentioned weight amount of organosilicone is added while grinding. The slurry is ground until the particle size is 200-500nm to obtain the ground slurry.

[0062] c. Add the above-mentioned weight amount of phosphoric acid to the slurry obtained in step b after sand milling to adjust the pH value to the range of 5.0 to 7.0, thereby obtaining 20% ​​bifenthrin nano-suspension.

[0063] Comparative Example 1

[0064] This embodiment provides a high-efficiency cyhalothrin suspension, which, by weight percentage, comprises the following components: 2.5% high-efficiency cyhalothrin, 3% sodium dodecylbenzenesulfonate (wetting agent), 3% phosphate ester (33SC) (dispersant), 0.1% formaldehyde (preservative), 0.1% phosphoric acid (pH adjuster), 4% ethylene glycol (antifreeze), 0.5% xanthan gum (thickener), 0.4% silicone (defoamer), and water to make up to 100%.

[0065] The specific steps for preparing the high-efficiency cyhalothrin suspension are as follows:

[0066] a. Weigh out the above-mentioned amounts of high-efficiency cyhalothrin, phosphate esters (33SC), sodium dodecylbenzenesulfonate, ethylene glycol, formaldehyde and water respectively, and put them into a mixing tank for shearing and mixing until uniform, to obtain the mixed material;

[0067] b. Under conditions of 20-30℃, the mixed material in step a is fed into a sand mill for sand milling. While grinding, the above-mentioned weight content of organosilicone is added. The material is sand milled until the particle size is 1-5μm to obtain the sand-milled material.

[0068] c. Add the milled material obtained in step b to the xanthan gum of the above weight percentage, and shear and stir evenly again. Add the phosphoric acid of the above weight percentage to adjust the pH value to 5.0-7.0, thus obtaining 2.5% high-efficiency cyhalothrin suspension.

[0069] Comparative Example 2

[0070] A high-efficiency cypermethrin suspension concentrate, comprising the following components by weight percentage: 5% high-efficiency cypermethrin technical grade, 3% sodium dodecylbenzenesulfonate (wetting agent), 2% phosphate ester (2210) (dispersant), 1% block polyether (5500) (dispersant), 0.1% formaldehyde (preservative), 0.1% phosphoric acid (pH adjuster), 4% ethylene glycol (antifreeze agent), 0.5% xanthan gum (thickener), 0.4% organosilicone (defoamer), and water to make up to 100%.

[0071] The specific steps for preparing the high-efficiency cyhalothrin suspension are as follows:

[0072] a. Weigh out the above-mentioned amounts of high-efficiency cyhalothrin, phosphate esters (2210), block polyethers (5500), sodium dodecylbenzene sulfonate, ethylene glycol, formaldehyde and water respectively, and put them into a stirring tank for shearing and mixing until uniform, to obtain the mixed material.

[0073] b. Under conditions of 20-30℃, the mixed material in step a is fed into a sand mill for sand milling. While grinding, the above-mentioned weight content of organosilicone is added. The material is sand milled until the particle size is 1-5μm to obtain the sand-milled material.

[0074] c. Add the milled material obtained in step b to the xanthan gum of the above weight percentage, and shear and stir evenly again. Add the phosphoric acid of the above weight percentage to adjust the pH value to 5.0-7.0, thus obtaining 2.5% high-efficiency cyhalothrin suspension.

[0075] Comparative Example 3

[0076] A deltamethrin suspension concentrate, by weight percentage, comprises the following components: deltamethrin 10%, sodium dodecylbenzenesulfonate 3% (wetting agent), phosphate ester (2210) 3% (dispersant), formaldehyde 0.1% (preservative), phosphoric acid 0.1% (pH adjuster), ethylene glycol 4% (antifreeze), xanthan gum 0.5% (thickener), silicone 0.4% (defoamer), and water to make up to 100%.

[0077] The specific steps for preparing the deltamethrin suspension are as follows:

[0078] a. Weigh out the above-mentioned amounts of deltamethrin, phosphate esters (2210), sodium dodecylbenzenesulfonate, ethylene glycol, formaldehyde and water respectively, and put them into a stirring tank for shearing and mixing until uniform, to obtain the mixed material;

[0079] b. Under conditions of 20-30℃, the mixed material in step a is fed into a sand mill for sand milling. While grinding, the above-mentioned weight content of organosilicone is added. The material is sand milled until the particle size is 1-5μm to obtain the sand-milled material.

[0080] c. Add the milled material obtained in step b to the xanthan gum of the above weight amount, and shear and stir evenly again. Add the phosphoric acid of the above weight amount to adjust the pH value to the range of 5.0 to 7.0, and thus obtain the deltamethrin suspension.

[0081] Comparative Example 4

[0082] A bifenthrin suspension concentrate, by weight percentage, comprises the following components: 20% bifenthrin, 3% sodium dodecylbenzenesulfonate (wetting agent), 3% block polyether (5050PB) (dispersant), 0.1% formaldehyde (preservative), 0.1% phosphoric acid (pH adjuster), 4% ethylene glycol (antifreeze agent), 0.5% xanthan gum (thickener), 0.4% silicone (defoamer), and water to make up to 100%.

[0083] The specific steps for preparing the bifenthrin suspension are as follows:

[0084] a. Weigh out the above-mentioned amounts of bifenthrin, block polyether (5050PB), sodium dodecylbenzenesulfonate, ethylene glycol, formaldehyde and water respectively, and put them into a mixing tank for shearing and mixing until uniform, to obtain the mixed material;

[0085] b. Under conditions of 20-30℃, the mixed material in step a is fed into a sand mill for sand milling. While grinding, the above-mentioned weight content of organosilicone is added. The material is sand milled until the particle size is 1-5μm to obtain the sand-milled material.

[0086] c. Add the milled material obtained in step b to the xanthan gum of the above weight amount, and shear and stir evenly again. Add the phosphoric acid of the above weight amount to adjust the pH value to the range of 5.0 to 7.0, and the bifenthrin suspension is obtained.

[0087] Example 5

[0088] Storage stability test

[0089] Storage stability tests were conducted on the sustained-release nano-suspensions from Examples 1-4, including heat storage tests and cold storage tests. The nano-suspensions were stored at 54±2℃ for 2 weeks and at 0±2℃ for 1 week, respectively. After storage, it was found that the sustained-release nano-suspensions from Examples 1-4 of this invention had a uniform appearance, no crystal precipitation under temperature changes, and good pourability. Specifically, D... 90 The particle size is between 200 and 300 nm, and the suspension rate is above 99% (see Table 1).

[0090] Table 1. Test results of physical stability determination of the sustained-release nano-suspension of the present invention.

[0091]

[0092] Example 6

[0093] Field application

[0094] Experimental crop: Tobacco, variety Yunyan 87

[0095] Target pests: Aphids

[0096] Test reagents: The treatment reagent was the 2.5% high-efficiency cyhalothrin nano-suspension of Example 1, the control reagent was the 2.5% high-efficiency cyhalothrin suspension of Comparative Example 1, and the blank control was an equal volume of water.

[0097] Experimental Methods: The experiment was conducted at the Hongyan Tobacco Station in Huaning County, Yuxi City, Yunnan Province, from July to August 2023. When the tobacco aphid population density exceeded the control threshold, backpack electric sprayers were used to spray the rice plants with each of the tested pesticides once. The pesticide solution dosage was 750 liters / hectare. Each pesticide treatment was replicated four times, with a plot area of ​​40 m². 2 Before applying the pesticide, the initial insect population was assessed. Five sampling points were used at 1, 3, 7, and 14 days after application, with five plants sampled at each point to determine the number of surviving insects. The experimental results were then analyzed and statistically significant, and a significance analysis was performed.

[0098] Insect population reduction rate (%) = [(Number of insects before application - Number of insects after application) ÷ Number of insects before application] × 100% Formula 1.

[0099] Control effect (%) = [(Pest population reduction rate in the treated area - pest population reduction rate in the blank control area) ÷ (100 - pest population reduction rate in the blank control area)] × 100% Formula 2.

[0100] Table 2. Results of inter-pharmaceutical efficacy tests of the sustained-release nano-suspension of the present invention against tobacco aphids.

[0101]

[0102] Note: Different lowercase letters after the data in the same column indicate the significance of the difference when P≤0.05 under Duncan's new multiple range test.

[0103] As shown in Table 2, the slow-release nano-suspension of Example 1 exhibited good control efficacy against tobacco aphids, with a significant improvement compared to Comparative Example 1. Furthermore, compared to the comparative example, the slow-release nano-suspension of Example 1 had a longer duration of action, maintaining a control efficacy of 89.6% even 14 days after application, far exceeding the 73.4% of the control.

[0104] Example 7

[0105] Field application

[0106] Experimental crop: Cabbage, variety Zhonggan 11

[0107] Target pest: Beet armyworm

[0108] Test reagents: 5% high-efficiency cyhalothrin nano-suspension of Example 2, 10% deltamethrin nano-suspension of Example 3, and 20% bifenthrin nano-suspension of Example 4; 2.5% high-efficiency cyhalothrin suspension of Comparative Example 2, deltamethrin suspension of Comparative Example 3, and bifenthrin suspension of Comparative Example 4; blank control was an equal volume of water.

[0109] Experimental Methods: The experiment was conducted in August and September 2022 at the experimental field of Northwest A&F University, Yangling District, Xianyang City, Shaanxi Province. During the peak period of beet armyworm infestation, each of the tested pesticides was sprayed once onto the cabbage plants using a backpack electric sprayer. The pesticide application rate was 900 liters / ha. Each pesticide treatment was replicated four times, with a plot area of ​​30 m². 2 Three, seven, and fourteen days after pesticide application, a five-point sampling method was used, with eight plants sampled at each point to investigate the number of all insect larvae at different ages on the entire plant. The initial population of beet armyworm larvae was assessed before pesticide application. The insect population reduction rate and control efficacy were calculated. Finally, the experimental results were analyzed and statistically significant, and a significance analysis was performed. The calculation methods for the insect population reduction rate and control efficacy are shown in Formulas 1 and 2.

[0110] Table 3. Field efficacy test results of the slow-release nano-suspension agent of the present invention for controlling cabbage and beet armyworm.

[0111]

[0112] Note: Different lowercase letters after the data in the same column indicate the significance of the difference when P≤0.05 under Duncan's new multiple range test.

[0113] As shown in Table 3, Examples 2-4 all showed good control effects against the beet armyworm. Compared with the comparative examples, the sustained-release nano-suspension formulations of Examples 1-4 had a significantly longer effective period against the beet armyworm and a significantly improved control effect. The examples showed significant differences compared with the comparative examples.

[0114] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A sustained-release nano-suspension agent, characterized in that, The raw materials are as follows by weight percentage: 1%–20% pyrethroid technical grade, 3%–8% wetting agent, 2%–7% dispersant, 4%–6% antifreeze, 0.05%–1% defoamer, 0.01%–1% preservative, 0.01%–0.4% pH adjuster, and water to 100%. The wetting agent is polyvinyl alcohol and sodium lignosulfonate, and the mass ratio of polyvinyl alcohol to sodium lignosulfonate is 1 to 3:

3. The particle size of the sustained-release nano-suspension is 200–500 nm.

2. The sustained-release nano-suspension agent according to claim 1, characterized in that, The pyrethroid technical grade includes one or more of the following: lambda-cyhalothrin, fenvalerate, benzyl chlorpyrifos, deltamethrin, cypermethrin, lambda-cyhalothrin, cis-cypermethrin, cypermethrin, fenvalerate, cypermethrin, cypermethrin, fenvalerate, cypermethrin, cypermethrin, cypermethrin, and bifenthrin.

3. The sustained-release nano-suspension agent according to claim 1, characterized in that, The dispersant includes one or both of phosphate esters and block polyethers.

4. The sustained-release nano-suspension agent according to claim 3, characterized in that, The phosphate ester includes one of 33SC, 500LQ, 2210 and 1020; the block polyether includes one of 5500 and 5050PB.

5. The sustained-release nano-suspension agent according to claim 1, characterized in that, The defoamer includes ester-ether type compounds, C8-C 10 The preservative comprises one or more of fatty alcohols, organosilicones, and silicone oils; the preservative comprises one or more of formaldehyde, sodium benzoate, and potassium sorbate; the pH adjuster comprises one or more of phosphoric acid, lactic acid, and citric acid; the pH value of the slow-release nano-suspension is 5.0 to 7.0; and the antifreeze is ethylene glycol.

6. A method for preparing a sustained-release nano-suspension according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) The pyrethroid technical, dispersant, wetting agent, antifreeze, preservative and water are mixed to obtain a mixed slurry; (2) The mixed slurry is milled, and the defoamer is added during the milling process to obtain the milled slurry; (3) The slurry after sand milling is mixed with the pH adjuster to obtain a slow-release nano suspension.

7. The preparation method according to claim 6, characterized in that, The grinding temperature is 20-30℃, and the grinding is performed to a particle size of 200-500nm.

8. The application of the sustained-release nano-suspension according to any one of claims 1 to 5 or the sustained-release nano-suspension prepared by the preparation method according to claim 6 or 7 in the prevention and control of pests or the preparation of insecticides.

9. The application according to claim 8, characterized in that, The pests include one or more of the following: aphids, bollworms, beet armyworms, tea green leafhoppers, and cutworms.

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