Insecticidal composition containing ethiprole and flonicamid

Abstract

The invention relates to the technical field of pesticides, and discloses an insecticidal composition containing ethiprole and flonicamid, which is characterized in that the ethiprole and the flonicamid are embedded in biodegradable polylactic acid-glycolic acid copolymer microcapsules; the microcapsules are suspended and dispersed in an aqueous medium containing an acrylic resin film-forming agent, an ultraviolet light absorber and agriculturally acceptable auxiliary materials. Through multi-layer protection and controlled release, the pesticide effect lasting period is effectively prolonged to 15-20 days, the application frequency and the dosage are reduced, and long-acting, efficient and environment-friendly pest control is achieved. The composition disclosed by the invention has excellent suspension stability, redispersibility, wettability and biological activity, and is suitable for being applied by adopting conventional spraying equipment. The insecticidal composition is suitable for preventing and treating various piercing-sucking mouthpart pests, such as aphids, plant hoppers, phylloxera and aleyrodid, and underground pests, such as grub cockroaches and wireworms. The composition can be widely applied to various crops such as rice, cotton, vegetables, fruit trees and tea trees.

Description

Technical Field

[0001] This invention belongs to the field of pesticide technology and relates to an insecticidal composition containing acetamiprid and flonicamid. Background Technology

[0002] Existing compound formulations, to achieve synergistic effects of two or more pesticide active ingredients, often employ traditional formulations such as emulsifiable concentrates (ECs) or wettable powders. Emulsifiable concentrates dissolve the active ingredient in an organic solvent and add an emulsifier, forming a stable emulsion upon contact with water, facilitating spray application. Their advantages include uniform dispersion of the active ingredient and rapid efficacy. Wettable powders, on the other hand, mix and grind the active ingredient with fillers, dispersants, wetting agents, and other adjuvants into a fine powder, which disperses and suspends upon contact with water. Their advantage lies in the absence of organic solvents, making them relatively more environmentally friendly. These two traditional formulations have indeed provided convenience for pesticide application in specific scenarios and, for a certain period, effectively solved problems related to pesticide dispersibility and ease of use, allowing the active ingredient to cover the crop surface relatively evenly, thereby exerting its insecticidal efficacy.

[0003] Taking acetamiprid and flonicamid as examples, when they are prepared as emulsifiable concentrates or wettable powders and applied to crop surfaces, the active ingredients are typically exposed directly to the external environment in the form of extremely fine droplets or particles. Traditional formulations aim to rapidly release the active ingredients to their target, but they lack physical barriers to protect the active ingredients and mechanisms for sustained release control. In this context, acetamiprid contains UV-sensitive groups in its molecular structure, making it highly susceptible to photolysis under sunlight, especially UV radiation. Once sprayed onto crop leaves, the exposed acetamiprid molecules are continuously attacked by UV radiation, leading to rapid decomposition and inactivation.

[0004] Correspondingly, as a water-soluble or easily dispersible compound, flonicamid, when applied in traditional formulations, is easily washed away by rainwater as its particles or dissolved molecules adhere to the crop surface. Although a film may form on the crop surface, the physical strength and water resistance of this film are often insufficient to withstand continuous rain or heavy rainfall, resulting in a significant loss of the active ingredient. This lack of adequate protection leads to a rapid and sustained decline in the effective concentration of the active ingredient on the crop surface after application.

[0005] According to practical data, the efficacy of pesticides drops to below 50% within just 7-10 days after application. This means that frequent reapplication is often necessary throughout the pest's life cycle to maintain effective control. This frequent reapplication not only increases labor costs in agricultural production but also directly leads to increased pesticide usage, exacerbating the potential risk of pesticide residues and placing unnecessary pressure on the ecological environment. Traditional formulations fail to effectively balance the immediate release of active ingredients with long-term protection. Especially when facing the inherent weaknesses of specific active ingredients, the lack of protective mechanisms becomes a fundamental obstacle restricting their application efficacy and promotion potential. Summary of the Invention

[0006] This invention aims to provide an insecticidal composition containing acetamiprid and flonicamid to address the technical contradictions of existing pesticide formulations where the active ingredients are easily degraded or lost due to environmental factors in practical applications, leading to short-lasting efficacy, high application frequency, increased dosage, and exacerbated environmental burden. Addressing the inherent characteristics of acetamiprid being susceptible to UV photolysis and flonicamid being easily washed away by rainwater, this invention constructs a multi-layered protection and controlled-release system to extend the effective action time of the active ingredients on the crop surface, thereby achieving long-lasting, highly effective, and environmentally friendly pest control.

[0007] To achieve the aforementioned objectives, this invention provides an insecticidal composition containing acetamiprid and flonicamid, characterized in that the composition is a microcapsule suspension and comprises the following components: acetamiprid, flonicamid, a biodegradable polylactic-co-glycolic acid copolymer, an acrylic resin film-forming agent, an ultraviolet absorber, and an agricultural additive. Acetaminophen and flonicamid are encapsulated within microcapsules composed of the polylactic-co-glycolic acid copolymer, forming microcapsules loaded with the active ingredients. These microcapsules are suspended and dispersed in an aqueous medium containing the acrylic resin film-forming agent, the ultraviolet absorber, and the agricultural additive.

[0008] In a preferred embodiment of the present invention, the microcapsule suspension contains 10% acetamiprid and 5% flonicamid by mass. The total mass fraction of the two active ingredients in the microcapsules is typically set within the range of 5% to 20% of the total mass of the microcapsules. The average particle size of the microcapsules is controlled within the range of 1 μm to 3 μm, and their total encapsulation efficiency of the active ingredients is greater than 90%. The particle size of the microcapsules is determined by laser diffraction particle size analyzer, with a median particle size D50 falling within the range of 1 μm to 3 μm, and a polydispersity index less than 0.3, to ensure the uniformity and stability of the microcapsule system.

[0009] Furthermore, the biodegradable polylactic acid-glycolic acid copolymer (PLA-GAC copolymer) serves as the wall material of the microcapsules. It is polymerized from L-lactic acid and glycolide via ring-opening polymerization, or from lactic acid and glycolic acid via condensation polymerization. The weight-average molecular weight of the PLA-GAC copolymer ranges from 10,000 Da to 100,000 Da. The molar ratio of lactic acid to glycolic acid in the PLA-GAC copolymer can be adjusted according to the desired release rate and degradation period of the active ingredient, typically selected between 50:50 and 85:15. When the molar ratio is 50:50, the PLA-GAC copolymer exhibits a relatively fast degradation rate, suitable for applications requiring rapid release; when the molar ratio is 75:25, the PLA-GAC copolymer has a moderate degradation rate, providing a sustained release period of 15 to 20 days; and when the molar ratio is 85:15, the PLA-GAC copolymer exhibits a relatively slow degradation rate, suitable for applications requiring a longer duration of effect. The glass transition temperature of the polylactic acid-glycolic acid copolymer is typically between 40°C and 60°C, and its melting point is typically between 160°C and 170°C. These physical parameters ensure the structural stability of the microcapsules during preparation and storage. The polylactic acid-glycolic acid copolymer is biodegraded in vivo and in the environment via ester bond hydrolysis, with the final products being lactic acid and glycolic acid. It exhibits good biocompatibility and metabolizability, and is environmentally friendly.

[0010] In a preferred embodiment of the present invention, the acrylic resin film-forming agent has a mass fraction of 2%. The acrylic resin film-forming agent is an aqueous acrylic copolymer emulsion, whose monomer components mainly include acrylates (e.g., butyl acrylate, isooctyl acrylate) and / or methacrylates (e.g., methyl methacrylate, butyl methacrylate), and a small amount of comonomers with carboxyl or hydroxyl functional groups (e.g., acrylic acid, methacrylic acid) to provide good adhesion and crosslinking sites. The weight-average molecular weight of the acrylic resin typically ranges from 50,000 g / mol to 200,000 g / mol. The glass transition temperature of the acrylic resin is preferably between 0°C and 30°C to ensure the formation of a flexible and continuous transparent film on the crop surface, which has excellent waterproof properties, good light transmittance, and strong adhesion to plant leaves. After being sprayed onto the crop surface, the film-forming agent causes the polymer particles to aggregate and form a dense, impermeable polymer film through water evaporation. This film effectively fixes the microcapsules to the crop surface and provides a physical barrier to prevent rainwater from washing away the active ingredients and microcapsules. The film also exhibits excellent moisture resistance and wind erosion resistance.

[0011] Further, the mass fraction of the ultraviolet absorber (2-hydroxy-4-n-octyloxybenzophenone) is 0.5%. This ultraviolet absorber is a highly efficient ultraviolet absorber that, through a rapid photoisomerization mechanism via intramolecular hydrogen bonds, converts absorbed ultraviolet energy into heat dissipation, thereby effectively inhibiting the decomposition of the active ingredient by ultraviolet radiation. The ultraviolet absorber has a broad-spectrum ultraviolet absorption capacity, with a maximum absorption wavelength range of 290 nm to 330 nm, and can efficiently absorb the main ultraviolet bands that cause the photolysis of acetamiprid. The ultraviolet absorber exhibits good photostability, thermal stability, and chemical stability, good compatibility with the other components, and can be uniformly dispersed in the formulation, ensuring the comprehensiveness of its photoprotective effect.

[0012] The agricultural adjuvants include, but are not limited to, dispersants, wetting agents, thickeners, antifreeze agents, defoamers, pH adjusters, stabilizers, and deionized water. These adjuvants are selected and proportioned according to the formulation requirements of the suspension to ensure the stability, spray performance, and bioactivity of the formulation.

[0013] In a preferred embodiment of the present invention, the dispersant is a polycarboxylate (e.g., sodium polyacrylate, polymaleic anhydride copolymer) or a naphthalenesulfonic acid formaldehyde condensate, with a mass fraction ranging from 0.5% to 5%. The dispersant, by adsorbing onto the surface of the microcapsules, generates steric hindrance and / or electrostatic repulsion effects, effectively preventing the microcapsules from agglomerating, settling, or flocculating in the aqueous medium, thereby maintaining the long-term physical stability of the suspension system.

[0014] Furthermore, the wetting agent is a nonionic surfactant, such as alkylphenol polyoxyethylene ether (e.g., nonylphenol polyoxyethylene ether or octylphenol polyoxyethylene ether) or fatty alcohol polyoxyethylene ether, with a mass fraction ranging from 0.1% to 2%. The wetting agent can reduce the surface tension of the liquid, promote rapid wetting and uniform dispersion of the microcapsule particles in the aqueous phase, and ensure good spreadability of the formulation on crop leaves after spraying.

[0015] In a preferred embodiment of the present invention, the thickener is one or more of xanthan gum, magnesium aluminum silicate, polyvinyl alcohol, or sodium carboxymethyl cellulose, with a mass fraction ranging from 0.1% to 1%. The thickener increases the viscosity of the suspension system, slows the settling rate of the microcapsules, thereby further enhancing the storage stability of the formulation and preventing solid-liquid separation. The thickener exhibits thixotropy under shear force, which is beneficial for spray application, and recovers its high viscosity upon standing.

[0016] Furthermore, the antifreeze is propylene glycol or glycerol, with a mass fraction ranging from 1% to 5%. The antifreeze lowers the freezing point of the aqueous medium, preventing the formulation from freezing during low-temperature storage or transportation, thereby avoiding microcapsule rupture or decreased stability of the formulation system due to ice crystal formation.

[0017] In a preferred embodiment of the present invention, the defoamer is an organosilicone emulsion type defoamer with a mass fraction ranging from 0.01% to 0.1%. The defoamer effectively inhibits foam generated during the production, storage, and application of the formulation, ensuring smooth production and stable application results.

[0018] Further, the pH adjuster is citric acid, a phosphate buffer system, or sodium hydroxide, and its addition amount is determined to adjust the pH value of the formulation to the range of 6.0 to 8.0. The pH adjuster is used to maintain the pH stability of the formulation system and prevent the active ingredients, polylactic acid-glycolic acid copolymer wall material, and other excipients from being degraded or deactivated due to extreme pH conditions.

[0019] The microcapsule preparation method of this invention can employ solvent evaporation, such as oil-in-water emulsion solvent evaporation or oil-in-oil emulsion solvent evaporation. The specific preparation steps are as follows: (1) Dissolution stage of active ingredients and wall material: A predetermined mass of acetamiprid and flonicamid is dissolved in a selected volatile organic solvent, such as dichloromethane, ethyl acetate, or chloroform, to form an active ingredient solution. The amount of the organic solvent is typically 10 to 20 times the total mass of the active ingredients.

[0020] A predetermined mass of polylactic acid-glycolic acid copolymer is dissolved in the same organic solvent to form a polylactic acid-glycolic acid copolymer solution. The concentration of the polylactic acid-glycolic acid copolymer is typically from 50 mg / mL to 150 mg / mL.

[0021] Subsequently, the active ingredient solution and the polylactic acid-glycolic acid copolymer solution are mixed evenly to obtain an organic phase solution of polylactic acid-glycolic acid copolymer containing the active ingredient. This mixing process is carried out on a magnetic stirrer at a stirring speed of 200 rpm to 400 rpm for 10 to 20 minutes.

[0022] (2) Primary emulsification stage: The organic phase solution of the polylactic acid-glycolic acid copolymer containing the active ingredient is slowly added dropwise to a first aqueous phase containing an emulsifier, such as a deionized aqueous solution containing polyvinyl alcohol (polyvinyl alcohol, molecular weight 10,000-70,000 Da, degree of hydrolysis 85%-90%), wherein the concentration of polyvinyl alcohol is 0.5% to 2% (mass fraction).

[0023] The dropping rate is controlled between 5 mL / min and 10 mL / min. During this process, primary emulsification is performed using a high-speed shear emulsifier or an ultrasonic disperser to disperse the organic phase into fine droplets, forming a water-in-oil primary emulsion. The emulsification temperature is controlled between 5°C and 15°C to reduce the evaporation of organic solvents.

[0024] (3) Secondary emulsification stage: If the oil-in-oil method is used, in the initial emulsification step, the aqueous phase (internal aqueous phase) is first dispersed into the polylactic acid-glycolic acid copolymer organic phase solution to form an oil-in-oil type initial emulsion. Some hydrophilic active ingredients or stabilizers can be dissolved in the internal aqueous phase.

[0025] Subsequently, the oil-in-oil primary emulsion is slowly added dropwise to a second aqueous phase (external aqueous phase) containing an emulsifier. This second aqueous phase typically also contains polyvinyl alcohol or other nonionic emulsifiers at a concentration of 0.5% to 2%. During this process, a secondary emulsification is performed again by high-speed shear emulsification or ultrasonic dispersion to form an oil-in-oil secondary emulsion. The emulsification conditions are similar to those of the primary emulsification, but parameters need to be adjusted to obtain the target particle size and stability.

[0026] (4) Solvent evaporation / extraction and solidification stage: The primary or secondary emulsion is transferred to a container containing a large amount of deionized water or diluted polyvinyl alcohol solution for solvent evaporation or extraction.

[0027] If the solvent evaporation method is used, the system is placed on a magnetic stirrer at a speed of 300 rpm to 600 rpm and stirred and evaporated under normal pressure or reduced pressure. The temperature is controlled at 25°C to 40°C and the duration is 4 to 8 hours to allow the organic solvent to fully evaporate.

[0028] If solvent extraction is used, the system is mixed with a large volume of non-solvent (e.g., deionized water), allowing the organic solvent to diffuse into the non-solvent while the microcapsule wall material solidifies. This process also requires continuous stirring.

[0029] As the organic solvent is removed, the polylactic acid-glycolic acid copolymer polymer precipitates and solidifies, forming solid microcapsules encapsulating the active ingredients.

[0030] (5) Washing and separation stage: After the microcapsules have completely solidified, they are separated from the supernatant by centrifugation or filtration.

[0031] The microcapsules were then washed multiple times with deionized water to thoroughly remove surface-adsorbed emulsifiers, free active ingredients, and residual organic solvents, ensuring the purity of the microcapsules. Centrifugation or filtration was performed after each wash.

[0032] (6) Drying stage: The washed microcapsule suspension is freeze-dried or vacuum-dried.

[0033] If freeze drying is used, the microcapsule suspension is first pre-frozen at -40°C to -80°C for 24 hours, and then placed in a freeze dryer and dried at a plate temperature of -20°C to -30°C and a vacuum degree of less than 10 Pa for 48 to 72 hours to obtain dried microcapsule powder.

[0034] If vacuum drying is used, the microcapsule suspension is dried at a temperature of 50°C to 60°C and a vacuum of less than 0.1 MPa for 24 to 48 hours.

[0035] The obtained dry microcapsule powder should have good flowability and be stored in a dry, light-protected environment.

[0036] The method for preparing the microcapsule suspension of the present invention includes the following steps: (1) Pre-dispersion stage: The microcapsule powder prepared and dried by the above method is mixed with a portion of deionized water and pre-dispersed under low-speed stirring to avoid the aggregation of microcapsules.

[0037] (2) Additive dissolution / dispersion stage: The wetting agent and dispersant are added sequentially to the microcapsule predispersed solution, and stirring is maintained at a medium speed to ensure that they are fully dissolved or uniformly dispersed. This process usually lasts 30 to 60 minutes.

[0038] (3) Functional component addition stage: Under stirring conditions, the acrylic resin film-forming agent and the ultraviolet absorber are slowly added. Stirring is continued to ensure that the film-forming agent and ultraviolet absorber are evenly distributed in the system. This process usually lasts for 1 to 2 hours.

[0039] (4) Thickening and stabilization stage: Add the thickener and adjust the stirring speed and stirring time until the system reaches the expected viscosity, forming a stable suspension system to ensure that the microcapsules do not settle.

[0040] (5) Addition of other excipients and pH adjustment: Add the antifreeze and defoamer in sequence and stir evenly. Use the pH adjuster to adjust the pH of the formulation to the range of 6.0 to 8.0.

[0041] (6) Volume adjustment and homogenization stage: Add the remaining deionized water to the total mass, and then perform high-speed shearing or grinding to ensure the uniformity of particle size and dispersion stability of the microcapsule suspension, and remove any possible micro agglomerates.

[0042] (7) Quality inspection and packaging: The final microcapsule suspension is subjected to quality inspection of indicators such as particle size distribution, suspension rate, pH value, viscosity, active ingredient content and storage stability. After passing the inspection, it is packaged.

[0043] Compared with the prior art, the beneficial effects of the present invention are: First, by encapsulating acetamiprid and flonicamid in biodegradable polylactic-co-glycolic acid (PLCA) microcapsules, the microcapsules act as the first physical barrier for the active ingredients, effectively preventing direct contact between the active ingredients and the external environment. After application, the PLAC wall material slowly degrades through ester bond hydrolysis under the influence of the crop surface microenvironment, thus achieving controlled release of the active ingredients. This controlled-release mechanism can precisely extend the release period of the active ingredients to 15 to 20 days, ensuring a continuous supply of effective pesticide concentrations throughout the pest's life cycle, significantly extending the duration of efficacy and solving the problem of rapid efficacy decay in traditional formulations. The biodegradability of PLAC ensures no residue in the environment; the degradation products, lactic acid and glycolic acid, are normal metabolic products in organisms, making them safe for both the environment and crops.

[0044] Secondly, after being sprayed onto the crop surface, the acrylic resin film-forming agent, through its unique film-forming properties, forms a dense, flexible, and transparent waterproof protective film on the outside of the microcapsules. This protective film acts as a second layer of physical protection, firmly attaching the microcapsules to the crop leaves and providing mechanical strength and a waterproof barrier. The waterproof film effectively prevents rainwater from washing away the microcapsules and released active ingredients, ensuring that the active ingredients maintain an effective concentration even after rain, thus improving the formulation's resistance to rain washout. Simultaneously, the film's good light transmittance ensures that crop photosynthesis is not affected.

[0045] Furthermore, the UV absorber is uniformly distributed throughout the microcapsule suspension system, particularly within the protective film formed by the film-forming agent and on the surface of the microcapsules. As a third layer of protection, it efficiently absorbs UV radiation with wavelengths from 290 nm to 330 nm. By consuming light energy, the UV absorber significantly inhibits the photolysis reaction of acetaminophen, which is sensitive to UV radiation. This photoprotective effect, combined with the physical isolation provided by the microcapsules, synergistically reduces the decomposition rate of acetaminophen under sunlight, ensuring its continued biological activity over a longer period.

[0046] Through the aforementioned multi-layered, synergistic, and controlled-release mechanism, this invention successfully overcomes the deep-seated contradictions in the prior art regarding the easy photodegradation of acetamiprid and the easy loss of flonicamid. The polylactic acid-glycolic acid copolymer microcapsules achieve sustained release of the active ingredient, resolving the balance between immediate release and long-lasting protection; the acrylic resin film-forming agent provides macroscopic waterproofing and adhesion protection; and the ultraviolet absorber provides targeted ultraviolet protection. The synergistic effect of these three components extends the efficacy of the composition to 15-20 days, thereby significantly reducing the frequency and total dosage of pesticide application, lowering labor costs and pesticide residue risks in agricultural production.

[0047] The composition of this invention exhibits excellent suspension stability, redispersibility, wettability, and bioactivity, making it suitable for application using conventional spraying equipment. It is effective in controlling various piercing-sucking pests, such as aphids, planthoppers, psyllids, and whiteflies, as well as underground pests, such as white cockroaches and wireworms. This composition can be widely applied to various crops, including rice, cotton, vegetables, fruit trees, and tea trees. Detailed Implementation

[0048] This invention provides an insecticidal composition containing acetamiprid and flonicamid, which exists in the form of a microcapsule suspension. It aims to overcome the technical challenge of rapid degradation or loss of active ingredients in existing pesticide formulations due to environmental factors by constructing a sophisticated multi-layered protection and controlled-release system, thereby achieving long-term, efficient control of target pests. This detailed embodiment will provide a detailed engineering description of each component of the composition, its preparation method, and its mechanism of action, supplemented with specific examples and comparative experimental data, to fully disclose the technical solution of this invention and ensure that those skilled in the art can understand and implement this invention without obstacles.

[0049] Example 1: Components and mass fractions: 10% acetamiprid, 5% flonicamid (total active ingredient content 10%), 8% polylactic acid-glycolic acid copolymer (lactic acid:glycolic acid = 50:50), 2% acrylic resin film-forming agent, 0.5% 2-hydroxy-4-n-octyloxybenzophenone, 2% polycarboxylate dispersant, 0.5% fatty alcohol polyoxyethylene ether wetting agent, 0.2% xanthan gum thickener, 3% propylene glycol antifreeze agent, 0.05% silicone emulsion defoamer, citric acid pH adjuster (adjust pH to 7.0), deionized water to 100%.

[0050] Preparation method: Microcapsules were prepared by solvent evaporation. Acetonitrile and flonicamid were dissolved in dichloromethane and mixed with a dichloromethane solution of polylactic acid-glycolic acid copolymer. An aqueous phase containing polyvinyl alcohol was added dropwise, and the mixture was emulsified by high-speed shearing to form a primary emulsion. The solvent was removed by stirring and evaporation under normal pressure, and the microcapsules were washed by centrifugation. The microcapsules were then mixed sequentially with excipients such as dispersant, wetting agent, and acrylic resin film-forming agent. After adjusting the pH and adjusting the volume, the mixture was homogenized by high-speed shearing to obtain a microcapsule suspension.

[0051] Parameters: Microcapsule D50 is 1.5μm, encapsulation efficiency is 92%, and suspension efficiency is 93%.

[0052] Example 2: Components and mass fractions: 7% acetamiprid, 8% flonicamid (total active ingredient content 15%), 10% polylactic acid-glycolic acid copolymer (lactic acid:glycolic acid = 75:25), 2% acrylic resin film-forming agent, 0.5% 2-hydroxy-4-n-octyloxybenzophenone, 3% naphthalenesulfonic acid formaldehyde condensate dispersant, 0.8% fatty alcohol polyoxyethylene ether wetting agent, 0.5% magnesium aluminum silicate thickener, 4% propylene glycol antifreeze agent, 0.08% silicone emulsion defoamer, phosphate buffer system pH adjuster (adjust pH to 7.2), deionized water to 100%.

[0053] Preparation method: Same as in Example 1, only the molar ratio of polylactic acid-glycolic acid copolymer and the proportion of active ingredients were adjusted.

[0054] Parameters: Microcapsule D50 is 2.0 μm, encapsulation efficiency is 95%, and suspension efficiency is 95%.

[0055] Example 3: Components and mass fractions: 10% acetamiprid, 10% flonicamid (total active ingredient content 20%), 12% polylactic acid-glycolic acid copolymer (lactic acid:glycolic acid = 85:15), 2% acrylic resin film-forming agent, 0.5% 2-hydroxy-4-n-octyloxybenzophenone, 4% polycarboxylate dispersant, 1.0% fatty alcohol polyoxyethylene ether wetting agent, 0.8% polyvinyl alcohol thickener, 5% glycerin antifreeze, 0.1% silicone emulsion defoamer, sodium hydroxide pH adjuster (adjust pH to 6.8), deionized water to 100%.

[0056] Preparation method: Same as in Example 1, except that the molar ratio of polylactic acid-glycolic acid copolymer, the total content of active ingredients, and the type of thickener are adjusted.

[0057] Parameters: Microcapsule D50 is 2.5μm, encapsulation efficiency is 93%, and suspension efficiency is 94%.

[0058] Example 4: Components and mass fractions: acetamiprid 5%, flonicamid 5% (total active ingredient content 10%), polylactic acid-glycolic acid copolymer (lactic acid:glycolic acid = 75:25) 9%, acrylic resin film-forming agent 2%, 2-hydroxy-4-n-octyloxybenzophenone 0.5%, naphthalenesulfonic acid formaldehyde condensate dispersant 2.5%, fatty alcohol polyoxyethylene ether wetting agent 0.6%, sodium carboxymethyl cellulose thickener 0.3%, propylene glycol antifreeze agent 3.5%, silicone emulsion defoamer 0.06%, citric acid pH adjuster (adjust pH to 7.1), deionized water to 100%.

[0059] Preparation method: Same as in Example 1, except that the amount of polylactic acid-glycolic acid copolymer and the type of thickener are adjusted.

[0060] Parameters: Microcapsule D50 is 1.8μm, encapsulation efficiency is 94%, and suspension efficiency is 95%.

[0061] Comparative Example 1: Components and mass fractions: acetamiprid 5%, flonicamid 10%, xylene 60%, alkylbenzene sulfonate calcium emulsifier 8%, methanol cosolvent 5%, deionized water to 100%.

[0062] Preparation method: Dissolve acetamiprid and flonicamid in a mixed solvent of xylene and methanol, add calcium alkylbenzene sulfonate, stir until completely dissolved, add deionized water and stir evenly to obtain emulsifiable oil.

[0063] Parameters: Emulsion stability 85% (no D50, encapsulation rate).

[0064] Comparative Example 2: Components and mass fractions: acetamiprid 5%, flonicamid 10%, kaolin 70%, naphthalenesulfonic acid formaldehyde condensate dispersant 5%, alkylphenol polyoxyethylene ether wetting agent 3%, magnesium stearate stabilizer 2%.

[0065] Preparation method: Mix all components and grind them to a fineness of less than 45 μm using an air jet mill to obtain a wettable powder.

[0066] Key parameters: Suspension rate 82% (without D50 or encapsulation rate).

[0067] Performance testing: Test subject: Crop aphids (piercing-sucking pests, the target pest for patented control). Application method: conventional spraying (dosage is 100g of active ingredient per hectare); Rain erosion resistance: The retention rate of control efficacy was determined after simulating moderate rainfall (20 mm) 24 hours after application. Control efficacy calculation: Control efficacy (%) = (Number of insects in the control group - Number of insects in the treatment group) / Number of insects in the control group × 100%.

[0068] And a data comparison table:

[0069] From the table above, we can obtain: As can be seen from the table data, the efficacy of Examples 1-4 (microcapsule suspensions) remained at 70%-85% 20 days after application, while the efficacy of Comparative Example 1 (emulsifiable concentrate) and Comparative Example 2 (wettable powder) was only 12%-15% after 20 days, showing a significant difference in the rate of decline. This is because the multi-layered protection and controlled-release system designed in this invention: polylactic acid-glycolic acid copolymer microcapsules act as the first barrier, slowly releasing the active ingredient through ester bond hydrolysis; acrylic resin film-forming agent forms a waterproof film (second barrier); 2-hydroxy-4-n-octyloxybenzophenone absorbs ultraviolet light (third barrier), collectively solving the problems of easy photolysis of acetamiprid and easy loss of flonicamid, achieving a 15-20 day duration of effectiveness (consistent with the technical effects of this invention).

[0070] Comparing Example 1 (50:50), Example 2 (75:25), and Example 3 (85:15), the degradation rate of polylactic acid-glycolic acid copolymer slows down and the effective period is prolonged as the proportion of lactic acid increases: Example 3 (85:15) showed a 20-day efficacy of 78%, significantly higher than the 65% of Example 1 (50:50). This verifies the technical description in this invention that a molar ratio of 50:50 results in faster degradation and 85:15 results in slower degradation, indicating that different effective period requirements can be adapted by adjusting the molar ratio.

[0071] Example 2 (15% active ingredient) and Example 4 (10% active ingredient) both used polylactic acid-glycolic acid copolymer in a 75:25 molar ratio. Both had a suspension rate of 95% and similar efficacy after 7 days, indicating that within the range of 5%-20% total active ingredient content (the range defined by this invention), the formulation can still maintain excellent suspension stability and the initial efficacy is not significantly affected. Although Example 3 (20%) had the highest active ingredient content, the encapsulation rate still reached 93%, proving that the technology of this invention can achieve effective encapsulation of high-content active ingredients.

[0072] The retention rate of post-rain control efficacy in Examples 1-4 reached 83%-92%, while that in Comparative Examples 1-2 was only 45%-50%. This is because the acrylic resin film-forming agent forms a dense waterproof film on the crop surface, firmly fixing the microcapsules and preventing rainwater erosion. This solves the problem of the sharp drop in efficacy after rain in traditional formulations and improves the environmental adaptability for field application.

[0073] In summary, the microcapsule suspension of the present invention, through multi-layered protection and controlled release design, is superior to traditional emulsifiable concentrates and wettable powders in terms of long-lasting effect, stability, and environmental adaptability. It can reduce the frequency and amount of application, thus meeting the invention's objectives of long-lasting effect, high efficiency, and environmental friendliness.

[0074] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An insecticidal composition comprising ethiprole and flonicamid, characterized in that, The composition is a microcapsule suspension agent, and comprises the following components: ethiprole, flonicamid, biodegradable polylactic acid-glycolic acid copolymer, acrylic resin film-forming agent, ultraviolet absorber, and agricultural adjuvant; The ethiprole and the flonicamid are embedded inside the microcapsules composed of the polylactic acid-glycolic acid copolymer, forming active ingredient-loaded microcapsules; The active ingredient-loaded microcapsules are suspended and dispersed in an aqueous medium comprising the acrylic resin film-forming agent, the ultraviolet absorber, and the agricultural adjuvant.

2. The insecticidal composition according to claim 1, characterized by, The mass fraction of the ethiprole in the microcapsule suspension agent is 10%, and the mass fraction of the flonicamid is 5%; The total mass fraction of the ethiprole and the flonicamid in the microcapsules is set in the range of 5% to 20% of the total mass of the microcapsules; The average particle size of the microcapsules is controlled in the range of 1 μm to 3 μm, specifically, the D50 median particle size of the microcapsules falls within the interval of 1 μm to 3 μm, and the polydispersity index thereof is less than 0.3; The total encapsulation rate of the active ingredients by the microcapsules is greater than 90%.

3. The insecticidal composition according to claim 1, wherein The biodegradable polylactic acid-glycolic acid copolymer as the wall material of the microcapsules is synthesized by one of the following synthetic methods: synthesized by ring-opening polymerization of L-lactic acid and ethylene glycol bis(carboxymethyl) ether; synthesized by polycondensation reaction of lactic acid and glycolic acid; the weight average molecular weight of the polylactic acid-glycolic acid copolymer ranges from 10,000 Da to 100,000 Da.

4. The insecticidal composition according to claim 3, characterized by, The molar ratio of lactic acid to glycolic acid in the polylactic acid-glycolic acid copolymer is selected between 50:50 and 85:15; The glass transition temperature of the polylactic acid-glycolic acid copolymer is between 40°C and 60°C, and the melting point thereof is between 160°C and 170°C; The polylactic acid-glycolic acid copolymer is biodegraded in vivo and in the environment through ester bond hydrolysis mechanism, and the final products are lactic acid and glycolic acid.

5. The insecticidal composition according to claim 1, wherein The mass fraction of the acrylic resin film-forming agent is 2%; The acrylic resin film-forming agent is an aqueous acrylic copolymer emulsion, the monomer components of which mainly include acrylic esters and / or methacrylic esters, and a small amount of comonomers with carboxyl or hydroxyl functional groups; The weight average molecular weight of the acrylic resin ranges from 50,000 g / mol to 200,000 g / mol.

6. The insecticidal composition according to claim 5, wherein The glass transition temperature of the acrylic resin is between 0°C and 30°C; After being sprayed onto the surface of crops, the film-forming agent forms a flexible, continuous, and transparent polymer film through water evaporation.

7. The insecticidal composition according to claim 1, wherein The mass fraction of the ultraviolet absorber is 0.5%; The ultraviolet absorber is 2-hydroxy-4-n-octyloxybenzophenone.

8. The insecticidal composition according to claim 1, wherein The agricultural adjuvant includes one or more of dispersants, wetting agents, thickening agents, antifreezing agents, antifoaming agents, pH regulators, stabilizers, and deionized water.

9. The insecticidal composition according to claim 8, characterized in that: The dispersant is a polycarboxylate or a naphthalene sulfonate formaldehyde condensate, and the mass fraction thereof ranges from 0.5% to 5%; The wetting agent is a non-ionic surfactant.

10. The insecticidal composition according to claim 8, wherein: the thickening agent is one or more of xanthan gum, magnesium aluminum silicate, polyvinyl alcohol, or sodium carboxymethyl cellulose, and has a mass fraction ranging from 0.1% to 1%; the antifreezing agent is propylene glycol or glycerol, and has a mass fraction ranging from 1% to 5%; the antifoaming agent is a silicone emulsion type antifoaming agent, and has a mass fraction ranging from 0.01% to 0.1%; and the pH adjusting agent is citric acid, a phosphate buffer system, or sodium hydroxide, and is added in an amount to adjust the pH of the preparation to a range of 6.0 to 8.0, and is used to maintain the pH of the preparation system stable. ​ ​ ​ ​

Images