Spraying agent for preventing and treating snails and its preparation method and application

Abstract

The application provides a spraying agent for preventing and treating snails and a preparation method and application thereof, and belongs to the technical field of pesticides. The spraying agent comprises ginkgo leaf extract, psoralea corylifolia fruit extract, bloodgrass extract, modified chitosan, hydroxypropyl-beta-cyclodextrin, tetrahydro-piperine, eucalyptol, polyvinyl alcohol, surfactant, dispersant and water. The spraying agent has both contact killing and stomach poisoning effects by using three plant source extracts as snail killing active ingredients. Tetrahydro-piperine and eucalyptol are compounded as penetration enhancers, which can effectively open the snail body surface channel, improve the penetration rate and bioavailability. The modified chitosan and polyvinyl alcohol form a water-resistant film skeleton, and the inclusion protection of hydroxypropyl-beta-cyclodextrin, so that the spraying agent forms a water-resistant protective film on the surface of plants or buildings. The spraying agent has the advantages of high efficiency, rainwater resistance, long persistence and the like, and can be widely applied to the prevention and treatment of snails on the surfaces of crops, flowers, lawns and buildings.

Description

Technical Field

[0001] This invention relates to the field of pesticide technology, specifically to a spray agent for controlling snails, its preparation method, and its application. Background Technology

[0002] Snails are common soft-bodied pests in agricultural production, urban greening, and horticulture. They have a wide diet, reproduce rapidly, and can damage crops, flowers, and lawns. They also frequently inhabit building surfaces, causing pollution or damage. Snails scrape plant leaves, stems, and fruits with their radula, causing mechanical damage and easily inducing secondary diseases, seriously affecting crop yield and quality. Currently, snail control mainly relies on two types of methods: physical control and chemical control.

[0003] Physical control methods mainly include manual capture, application of salt, quicklime, or wood ash. These methods are simple to operate, but suffer from high labor intensity, low efficiency, significant susceptibility to rain erosion, and short-lasting effects, making it difficult to achieve large-scale and sustainable control. Chemical control primarily uses chemical molluscicides, such as metaldehyde and carbaryl. While these agents are fast-acting and easy to use, they have drawbacks such as high toxicity, long residual time in the environment, and the potential for resistance.

[0004] Therefore, developing a snail control product that is highly efficient, environmentally friendly, has a long-lasting effect, and is resistant to rain washout is of great practical significance and application value. Summary of the Invention

[0005] The purpose of this invention is to provide a spray agent for snail control, its preparation method, and its application. The spray agent provided by this invention has both high resistance to rainwater erosion and efficient snail killing effect.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a spray for controlling snails, comprising the following raw materials in parts by weight: 1-3 parts of Ginkgo biloba leaf extract, 0.5-1 part of Psoralea corylifolia fruit extract, 0.8-1.2 parts of Hedyotis diffusa extract, 1-2 parts of modified chitosan, 0.5-1.5 parts of hydroxypropyl-β-cyclodextrin, 0.1-0.15 parts of tetrahydropiperine, 0.8-1.2 parts of eucalyptol, 0.8-1.2 parts of polyvinyl alcohol 1788, 1.5-2.3 parts of surfactant, 0.8-1.5 parts of dispersant, and 150-180 parts of water.

[0007] Preferably, the preparation method of the ginkgo leaf extract includes: pulverizing ginkgo leaves, mixing with a solvent, performing reflux extraction, filtering, and purifying the filtrate with macroporous resin to obtain the ginkgo leaf extract; the solvent is composed of an ethanol solution with a volume fraction of 83%-88% and an ethyl acetate solution with a volume fraction of 3%-7% in a volume ratio of 1:(1-3); the reflux extraction temperature is 75-80℃, the extraction is performed 1-3 times, and each extraction lasts 1-3 hours.

[0008] More preferably, the macroporous adsorption resin is AB-8 type macroporous adsorption resin.

[0009] Preferably, the preparation method of the Psoralea corylifolia fruit extract includes: pulverizing Psoralea corylifolia fruit, enzymatically hydrolyzing it with a compound enzyme, adding methanol for ultrasonic extraction, centrifuging, concentrating the supernatant, and drying it to obtain the Psoralea corylifolia fruit extract.

[0010] More preferably, the complex enzyme is composed of cellulase and pectinase in a mass ratio of (4-6):(2-4); the ultrasonic extraction temperature is 37-42℃, the frequency is 20-30kHz, and the time is 25-35min.

[0011] Preferably, the preparation method of the *Hedyotis diffusa* extract includes: pulverizing *Hedyotis diffusa* root, mixing it with a 75%-85% ethanol solution (by volume), treating it with a high-voltage pulsed electric field, performing microwave extraction, filtering, concentrating the filtrate, and drying to obtain the *Hedyotis diffusa* extract; the electric field strength of the high-voltage pulsed electric field treatment is 15-20 kV / cm, the pulse width is 20-30 μs, and the number of pulses is 8-12.

[0012] More preferably, the microwave extraction temperature is 50-55℃, the power is 200-250W, and the time is 5-10min.

[0013] Preferably, the surfactant comprises polyether-modified polysiloxane and propylene glycol alginate; the dispersant comprises sodium lignosulfonate and polycarboxylate.

[0014] The present invention also provides a method for preparing the above-mentioned spraying agent, comprising: mixing hydroxypropyl-β-cyclodextrin with 30-35 parts of water, then mixing and stirring it with ginkgo leaf extract, psoralea fruit extract, spatholobus extract, tetrahydropiperine and eucalyptol, and ultrasonically treating it to obtain a cyclodextrin inclusion complex solution; mixing modified chitosan with 15-20 parts of water, then mixing it with the cyclodextrin inclusion complex solution, and stirring to obtain an encapsulation mixture; mixing polyvinyl alcohol 1788 with 10-15 parts of water and heating it to obtain a polyvinyl alcohol solution; mixing the remaining water, surfactant and dispersant to obtain a dispersion; and mixing the dispersion, encapsulation mixture and polyvinyl alcohol solution, homogenizing them to obtain the spraying agent.

[0015] The present invention also provides an application of the above-described spray agent in the preparation of snail control products.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a spray agent for snail control comprising: ginkgo leaf extract, psoralea fruit extract, bloodwort extract, modified chitosan, hydroxypropyl-β-cyclodextrin, tetrahydropiperine, eucalyptol, polyvinyl alcohol 1788, surfactant, dispersant and water.

[0017] This invention's spray agent uses three plant-derived extracts as molluscicidal active ingredients: Ginkgo biloba leaf extract disrupts the snail's surface mucus barrier and interferes with nerve conduction; Psoralea corylifolia fruit extract inhibits cholinesterase; and Bloodwort extract damages soft tissue. The combination of these three ingredients provides both contact and stomach poison effects. Tetrahydropiperine and eucalyptol, combined as penetration enhancers, effectively open the snail's surface channels, significantly improving the penetration rate and bioavailability of the active ingredients. Modified chitosan and polyvinyl alcohol 1788 form a flexible, water-resistant film-forming framework, which, combined with the inclusion protection of hydroxypropyl-β-cyclodextrin, allows the spray agent to form an erosion-resistant protective film on plant or building surfaces.

[0018] Experiments show that the spray agent of this invention retains 73.5% efficacy even after 24 hours of rain washout, significantly outperforming commercially available chemical control agents. The spray agent provided by this invention has advantages such as high efficiency, environmental friendliness, rain resistance, and long-lasting effectiveness, and can be widely used for snail control on crops, flowers, lawns, and building surfaces. Detailed Implementation

[0019] This invention provides a spray for controlling snails, comprising the following raw materials in parts by weight: 1-3 parts of Ginkgo biloba leaf extract, 0.5-1 part of Psoralea corylifolia fruit extract, 0.8-1.2 parts of Hedyotis diffusa extract, 1-2 parts of modified chitosan, 0.5-1.5 parts of hydroxypropyl-β-cyclodextrin, 0.1-0.15 parts of tetrahydropiperine, 0.8-1.2 parts of eucalyptol, 0.8-1.2 parts of polyvinyl alcohol 1788, 1.5-2.3 parts of surfactant, 0.8-1.5 parts of dispersant, and 150-180 parts of water.

[0020] The preferred method for preparing the ginkgo leaf extract of the present invention includes: pulverizing ginkgo leaves, mixing with a solvent, performing reflux extraction, filtering, and purifying the filtrate with a macroporous resin to obtain the ginkgo leaf extract; the solvent is preferably composed of an 83%-88% ethanol solution and a 3%-7% ethyl acetate solution in a volume ratio of 1:(1-3), more preferably composed of an 85% ethanol solution and a 5% ethyl acetate solution in a volume ratio of 1:2; the reflux extraction temperature is preferably 75-80℃, more preferably 78℃, the number of extractions is preferably 1-3 times, more preferably 2 times, each extraction is preferably 1-3 hours, more preferably 2 hours; the macroporous adsorption resin is preferably AB-8 type macroporous adsorption resin.

[0021] The preferred method for preparing the Psoralea corylifolia fruit extract of the present invention includes: pulverizing Psoralea corylifolia fruit, enzymatically hydrolyzing it with a compound enzyme, adding methanol for ultrasonic extraction, centrifuging, concentrating the supernatant, and drying to obtain the Psoralea corylifolia fruit extract; the compound enzyme is preferably composed of cellulase and pectinase in a mass ratio of (4-6):(2-4), more preferably 5:3; the enzymatic hydrolysis temperature is preferably 37-42℃, more preferably 40℃, the pH value is preferably 4.5-5, more preferably 4.8, and the time is preferably 40-60 min, more preferably 50 min; the ultrasonic extraction temperature is preferably 37-42℃, more preferably 40℃, the frequency is preferably 20-30 kHz, more preferably 25 kHz, and the time is preferably 25-35 min, more preferably 30 min.

[0022] The preferred method for preparing the *Hedyotis diffusa* extract of the present invention includes: pulverizing *Hedyotis diffusa* roots, mixing with a 75%-85% (v / v) ethanol solution, treating with a high-voltage pulsed electric field, performing microwave extraction, filtering, concentrating the filtrate, and drying to obtain the *Hedyotis diffusa* extract; the electric field strength of the high-voltage pulsed electric field treatment is preferably 15-20 kV / cm, more preferably 18 kV / cm, the pulse width is preferably 20-30 μs, more preferably 25 μs, and the number of pulses is preferably 8-12, more preferably 10; the microwave extraction temperature is preferably 50-55℃, more preferably 52℃, the power is preferably 200-250 W, more preferably 230 W, and the time is preferably 5-10 min, more preferably 8 min.

[0023] This invention utilizes Ginkgo biloba leaf extract, Psoralea corylifolia fruit extract, and Hedyotis diffusa extract as active ingredients in a spray for killing snails. The combination of these three ingredients forms a multi-target, multi-layered plant-derived snail-killing core system, significantly enhancing the control effect against snails. Specifically, Ginkgo biloba leaf extract is rich in flavonoids and terpenoid lactones, which can disrupt the snail's mucus barrier and epidermal cell structure, interfere with neuromuscular transmission, and inhibit snail feeding, crawling, and reproduction, exhibiting contact and stomach poison activity. The Psoralea corylifolia fruit extract contains active ingredients such as furanocoumarins, which can inhibit cholinesterase and metabolic activity in snails, reducing their mobility and survival rate. Hedyotis diffusa extract is rich in alkaloids, which can rapidly damage the snail's soft tissue and digestive system, disrupting its physiological metabolic functions, shortening the lethal time, and enhancing the agent's rapid effect. The combination of these three ingredients provides complementary rapid and sustained effects, targeting multiple points and significantly improving the overall snail-killing efficacy.

[0024] In this invention, tetrahydropiperine and eucalyptol act as penetration enhancers in the snail control system, exhibiting a synergistic effect when combined. Tetrahydropiperine, with its strong lipid solubility and cell membrane penetrability, efficiently loosens the snail's mucus layer and epidermal layer, opening channels for the active ingredient to enter the insect, significantly increasing the penetration rate and dosage of the active ingredient, and enhancing contact and stomach poison effects. Eucalyptol not only reduces the surface tension of the pesticide solution, improving its wetting and spreading properties on the snail's body and plant leaves, but also easily penetrates biomembranes, disrupting the ordered lipid structure and increasing drug penetration. The two work synergistically to enhance overall efficacy and accelerate the killing effect.

[0025] The surfactants described in this invention preferably include polyether-modified polysiloxane and propylene glycol alginate. The combination of these two substances reduces the surface tension of the drug solution, enhances its wetting, spreading, and adhesion abilities on plant / building surfaces and snail bodies, expands the contact area of ​​the drug, promotes the penetration and absorption of active ingredients, and significantly improves the efficacy of the drug.

[0026] The dispersant described in this invention preferably includes sodium lignosulfonate and polycarboxylate. The dispersant prevents the sedimentation, aggregation, and stratification of solid active ingredient particles, maintains the uniformity and stability of the spray agent system, ensures consistent concentration during spraying, avoids localized phytotoxicity, and improves the ease of use and efficacy stability of the spray agent.

[0027] In this invention, modified chitosan and polyvinyl alcohol 1788 form a flexible and water-resistant film-forming framework, constructing a continuous and dense protective film on plants and hard surfaces, thereby improving erosion resistance; hydroxypropyl-β-cyclodextrin encapsulates and modifies the chitosan to embed the active ingredients, reducing water loss; compound surfactants enhance interfacial wetting and adhesion, and dispersants ensure system uniformity and film integrity.

[0028] This invention's spray agent uses plant-derived compound active ingredients as its core, possessing both contact and stomach poison effects. It can quickly destroy the snail's surface mucus barrier and soft tissue, inhibiting its metabolism, movement, and reproduction, thus achieving highly efficient extermination. Through film formation and encapsulation, it forms a water-resistant and erosion-resistant protective film on plant and building surfaces, extending the effective period and reducing agent loss. It can be widely used on crops, flowers, lawns, and hard building surfaces to effectively control snail damage and reduce the occurrence of secondary diseases.

[0029] The present invention also provides a method for preparing the above-mentioned spraying agent, comprising: mixing hydroxypropyl-β-cyclodextrin with 30-35 parts of water, then mixing and stirring it with ginkgo leaf extract, psoralea fruit extract, spatholobus extract, tetrahydropiperine and eucalyptol, and ultrasonically treating it to obtain a cyclodextrin inclusion complex solution; mixing modified chitosan with 15-20 parts of water, then mixing it with the cyclodextrin inclusion complex solution, and stirring to obtain an encapsulation mixture; mixing polyvinyl alcohol 1788 with 10-15 parts of water and heating it to obtain a polyvinyl alcohol solution; mixing the remaining water, surfactant and dispersant to obtain a dispersion; and mixing the dispersion, encapsulation mixture and polyvinyl alcohol solution, homogenizing them to obtain the spraying agent.

[0030] The spray agent of this invention can be directly applied to crops, flowers, lawns and other plants, and can also be sprayed on hard surfaces such as building walls, stone and fences.

[0031] Plant surface application method: Apply at the initial stage of snail infestation or in the evening / on a cloudy day, avoiding high temperature, strong light and 2 hours before rain. Spray evenly on the front and back of the leaves, stems, soil around the roots and the entire lawn, until the leaves are moist but not dripping. Focus on spraying areas where snails often appear.

[0032] Application on building surfaces: Remove dust, moss, and debris from walls, stone, bases, etc., keep the surface dry, and spray evenly with a sprayer or spray gun to form a continuous protective film. Pay special attention to corners, gaps, baseboards, and other areas where snails can easily crawl.

[0033] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] Unless otherwise specified, the following embodiments are all conventional methods.

[0035] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0036] Cellulase, with an enzyme activity of 10,000 U / g, was sourced from Shandong Jida Biotechnology Co., Ltd.; pectinase, with an enzyme activity of 5,000 U / g, was sourced from Ningxia Hui Autonomous Region Xiasheng Industrial Group Co., Ltd.; modified chitosan, specifically chitosan hydrochloride, was sourced from Shanxi Ruifengtai Biotechnology Co., Ltd.; hydroxypropyl-β-cyclodextrin was sourced from Xi'an Paifite Industrial Co., Ltd.; eucalyptol was sourced from Jiangxi Yisenyuan Plant Fragrance Co., Ltd.; polyvinyl alcohol 1788, with a viscosity of 19.5-32.0 mPa·s, was sourced from Inner Mongolia Shuangxin Environmental Protection Materials Co., Ltd.; polyether-modified polysiloxane, model SR-37A, was sourced from Guangdong Leibang High-Tech Materials Co., Ltd.; propylene glycol alginate was sourced from Qingdao Mingyue Marine Technology Co., Ltd.; polycarboxylate, model 5040, was sourced from Shandong Yousu Chemical Technology Co., Ltd.; and fatty alcohol polyoxyethylene ether-9 was sourced from CNOOC Shell Petrochemical Co., Ltd. Example 1

[0037] (1) Preparation of Ginkgo biloba extract Ginkgo leaves were pulverized and passed through a 200-mesh sieve. They were mixed with 10 times their weight of solvent and extracted twice by reflux at 78°C for 2 hours each time. The extracts were filtered, and the filtrates were combined and concentrated to 1 / 3 of the filtrate volume. After adsorption by AB-8 macroporous adsorption resin, the extracts were eluted sequentially with 20% ethanol solution, 45% ethanol solution, and 75% ethanol solution. The eluents of 45% ethanol solution and 75% ethanol solution were collected, combined, concentrated under reduced pressure to remove ethanol, and freeze-dried to a moisture content of 1.49 wt% to obtain ginkgo leaf extract. The solvent consists of an 85% ethanol solution and a 5% ethyl acetate solution in a volume ratio of 1:2.

[0038] (2) Preparation of Psoralea corylifolia fruit extract The fruit of Psoralea corylifolia was pulverized and passed through a 400-mesh sieve. It was then mixed with 6 times its weight of water, and a compound enzyme was added. The mixture was enzymatically hydrolyzed at 40°C and pH 4.8 for 50 min. The enzyme was then inactivated, and methanol was added until the methanol volume fraction reached 65%. The mixture was then ultrasonically extracted at 40°C and 25 kHz for 30 min. After centrifugation, the supernatant was concentrated under reduced pressure to remove methanol. The extract was then freeze-dried until the moisture content was 2.17 wt% to obtain the Psoralea corylifolia fruit extract. The complex enzyme consists of cellulase and pectinase in a mass ratio of 5:3.

[0039] (3) Preparation of Bloodweed Extract The roots of *Gnaphalium affine* were pulverized and passed through a 300-mesh sieve. They were mixed with 12 times their weight of 80% ethanol solution and treated with a high-voltage pulsed electric field. The mixture was then microwaved at 52°C and 230W for 8 minutes. After filtration, the filtrate was concentrated and freeze-dried to a moisture content of 1.94 wt% to obtain *Gnaphalium affine* extract. The electric field strength of the high-voltage pulse electric field treatment is 18 kV / cm, the pulse width is 25 μs, and the number of pulses is 10.

[0040] (4) Weighing Weigh the following ingredients according to their respective weight proportions: 2 parts Ginkgo biloba extract, 0.8 parts Psoralea corylifolia fruit extract, 1 part Hedyotis diffusa extract, 1.5 parts modified chitosan, 1 part hydroxypropyl-β-cyclodextrin, 0.12 parts tetrahydropiperine, 1 part eucalyptol, 1 part polyvinyl alcohol 1788, 1 part polyether-modified polysiloxane, 1 part propylene glycol alginate, 0.6 parts sodium lignosulfonate, 0.6 parts polycarboxylate, and 165 parts water.

[0041] (5) Preparation of spraying agent Hydroxypropyl-β-cyclodextrin was mixed with 32 parts of water, and then Ginkgo biloba extract, Psoralea corylifolia fruit extract, Gynostemma pentaphyllum extract, piperine tetrahydrocorydaline, and eucalyptol were added sequentially. The mixture was stirred at 500 rpm for 30 min and then sonicated at 20 kHz for 20 min to obtain a cyclodextrin inclusion complex solution. Modified chitosan was mixed with 18 parts of water to obtain a modified chitosan solution. The cyclodextrin inclusion complex solution was added to the modified chitosan solution and stirred at 400 rpm for 25 min to obtain an encapsulation mixture. Polyether-modified polysiloxane, propylene glycol alginate, sodium lignosulfonate, and polycarboxylate were added sequentially to the remaining water and stirred at 600 rpm for 20 min to obtain a dispersion. Polyvinyl alcohol 1788 was mixed with 12 parts of water, heated to 83°C, and stirred at 200 rpm for 15 min to obtain a polyvinyl alcohol solution. The dispersion and polyvinyl alcohol solution were added to the encapsulation mixture and stirred at 500 rpm for 30 min. The mixture was homogenized twice at 30 MPa to obtain a snail-control spray. Example 2

[0042] (1) Preparation of Ginkgo biloba extract Ginkgo leaves were pulverized and passed through a 150-mesh sieve, mixed with 8 times their weight of solvent, and extracted by reflux at 75°C three times, 1 hour each time. After filtration, the filtrates were combined and concentrated to 1 / 2 of the filtrate volume. After adsorption by AB-8 macroporous adsorption resin, the extract was eluted sequentially with 18% ethanol solution, 42% ethanol solution, and 72% ethanol solution. The eluents of 42% ethanol solution and 72% ethanol solution were collected, combined, concentrated under reduced pressure to remove ethanol, and freeze-dried to a moisture content of 2.05 wt% to obtain ginkgo leaf extract. The solvent consists of an 83% ethanol solution and a 3% ethyl acetate solution in a 1:1 volume ratio.

[0043] (2) Preparation of Psoralea corylifolia fruit extract The fruit of Psoralea corylifolia was pulverized and passed through a 350-mesh sieve. It was then mixed with 5 times its weight of water, and a compound enzyme was added. The mixture was enzymatically hydrolyzed at 37°C and pH 4.5 for 60 min. The enzyme was then inactivated, and methanol was added until the methanol volume fraction reached 60%. The mixture was then ultrasonically extracted at 37°C and 20 kHz for 35 min. After centrifugation, the supernatant was concentrated under reduced pressure to remove methanol. The extract was then freeze-dried until the moisture content was 1.83 wt% to obtain the Psoralea corylifolia fruit extract. The complex enzyme consists of cellulase and pectinase in a mass ratio of 4:2.

[0044] (3) Preparation of Bloodweed Extract The roots of *Hedyotis diffusa* were pulverized and passed through a 250-mesh sieve. They were mixed with 10 times their weight of a 75% ethanol solution and treated with a high-voltage pulsed electric field. The mixture was then microwaved at 50°C and 200W for 10 minutes. After filtration, the filtrate was concentrated and freeze-dried to a moisture content of 2.31 wt% to obtain *Hedyotis diffusa* extract. The electric field strength of the high-voltage pulse electric field treatment is 15 kV / cm, the pulse width is 20 μs, and the number of pulses is 12.

[0045] (4) Weighing Weigh out the following ingredients according to their respective weight proportions: 1 part Ginkgo biloba extract, 0.5 part Psoralea corylifolia fruit extract, 0.8 part Hedyotis diffusa extract, 1 part modified chitosan, 0.5 part hydroxypropyl-β-cyclodextrin, 0.1 part tetrahydropiperine, 0.8 part eucalyptol, 0.8 part polyvinyl alcohol 1788, 0.7 part polyether-modified polysiloxane, 0.8 part propylene glycol alginate, 0.4 part sodium lignosulfonate, 0.4 part polycarboxylate, and 150 parts water.

[0046] (5) Preparation of spraying agent Hydroxypropyl-β-cyclodextrin was mixed with 30 parts of water, and then Ginkgo biloba extract, Psoralea corylifolia fruit extract, Gynostemma pentaphyllum extract, piperine tetrahydropiperine, and eucalyptol were added sequentially. The mixture was stirred at 400 rpm for 35 min and then sonicated at 18 kHz for 23 min to obtain a cyclodextrin inclusion complex solution. Modified chitosan was mixed with 15 parts of water to obtain a modified chitosan solution. The cyclodextrin inclusion complex solution was added to the modified chitosan solution and stirred at 350 rpm for 28 min to obtain an encapsulation mixture. Polyether-modified polysiloxane, propylene glycol alginate, sodium lignosulfonate, and polycarboxylate were added sequentially to the remaining water and stirred at 550 r / min for 25 min to obtain a dispersion. Polyvinyl alcohol 1788 was mixed with 10 parts of water, heated to 80℃, and stirred at 180 r / min for 18 min to obtain a polyvinyl alcohol solution. The dispersion and polyvinyl alcohol solution were added to the encapsulation mixture, stirred at 500 r / min for 30 min, and homogenized twice at 30 MPa to obtain a snail-controlling spray. Example 3

[0047] (1) Preparation of Ginkgo biloba extract Ginkgo leaves were pulverized and passed through a 250-mesh sieve, mixed with 12 times their weight of solvent, and extracted by reflux at 80°C for 3 hours. After filtration, the filtrate was concentrated to 1 / 4 of its volume and adsorbed onto AB-8 macroporous adsorption resin. The filtrate was then eluted sequentially with 25% ethanol solution, 48% ethanol solution, and 78% ethanol solution. The eluents of 48% ethanol solution and 78% ethanol solution were collected, combined, concentrated under reduced pressure to remove ethanol, and freeze-dried to a moisture content of 1.73 wt% to obtain ginkgo leaf extract. The solvent consists of an 88% ethanol solution and a 7% ethyl acetate solution in a volume ratio of 1:3.

[0048] (2) Preparation of Psoralea corylifolia fruit extract The fruit of Psoralea corylifolia was pulverized and passed through a 450-mesh sieve. It was then mixed with 7 times its weight of water, and a compound enzyme was added. The mixture was enzymatically hydrolyzed at 42°C and pH 5 for 40 min. The enzyme was then inactivated, and methanol was added until the methanol volume fraction reached 70%. The mixture was then ultrasonically extracted at 42°C and 30 kHz for 25 min. After centrifugation, the supernatant was concentrated under reduced pressure to remove methanol. The mixture was then freeze-dried until the moisture content was 1.59 wt% to obtain the Psoralea corylifolia fruit extract. The complex enzyme consists of cellulase and pectinase in a mass ratio of 6:4.

[0049] (3) Preparation of Bloodweed Extract The roots of *Gnaphalium affine* were pulverized and passed through a 350-mesh sieve. They were mixed with 15 times their weight of 85% ethanol solution and treated with a high-voltage pulsed electric field. The mixture was then microwaved at 55°C and 250W for 5 minutes. After filtration, the filtrate was concentrated and freeze-dried to a moisture content of 2.33 wt% to obtain *Gnaphalium affine* extract. The electric field strength of the high-voltage pulse electric field treatment is 20kV / cm, the pulse width is 30μs, and the number of pulses is 8.

[0050] (4) Weighing Weigh out the following ingredients according to their respective weight proportions: 3 parts Ginkgo biloba extract, 1 part Psoralea corylifolia fruit extract, 1.2 parts Hedyotis diffusa extract, 2 parts modified chitosan, 1.5 parts hydroxypropyl-β-cyclodextrin, 0.15 parts tetrahydropiperine, 1.2 parts eucalyptol, 1.2 parts polyvinyl alcohol 1788, 1.5 parts polyether-modified polysiloxane, 1.8 parts propylene glycol alginate, 0.7 parts sodium lignosulfonate, 0.8 parts polycarboxylate, and 180 parts water.

[0051] (5) Preparation of spraying agent Hydroxypropyl-β-cyclodextrin was mixed with 35 parts of water, and then Ginkgo biloba extract, Psoralea corylifolia fruit extract, Gynostemma pentaphyllum extract, piperine tetrahydropiperine, and eucalyptol were added sequentially. The mixture was stirred at 550 rpm for 25 min and then sonicated at 22 kHz for 18 min to obtain a cyclodextrin inclusion complex solution. Modified chitosan was mixed with 20 parts of water to obtain a modified chitosan solution. The cyclodextrin inclusion complex solution was added to the modified chitosan solution and stirred at 450 rpm for 23 min to obtain an encapsulation mixture. Polyether-modified polysiloxane, propylene glycol alginate, sodium lignosulfonate, and polycarboxylate were added sequentially to the remaining water and stirred at 650 r / min for 17 min to obtain a dispersion. Polyvinyl alcohol 1788 was mixed with 15 parts of water, heated to 85°C, and stirred at 250 r / min for 12 min to obtain a polyvinyl alcohol solution. The dispersion and polyvinyl alcohol solution were added to the embedding mixture, stirred at 550 r / min for 25 min, and homogenized once at 35 MPa to obtain a snail-controlling spray.

[0052] Comparative Example 1 The difference between this comparative example and Example 1 is that the AB-8 type macroporous adsorption resin in step (1) is replaced with the S-8 type macroporous adsorption resin.

[0053] Comparative Example 2 The difference between this comparative example and Example 1 is that "add methanol to a volume fraction of 65%" in step (2) is replaced with "add anhydrous ethanol to a volume fraction of 65%".

[0054] Comparative Example 3 The difference between this comparative example and Example 1 is that the “80% ethanol solution by volume” in step (3) is replaced with “deionized water”.

[0055] Comparative Example 4 The difference between this comparative example and Example 1 is that "0.12 parts of tetrahydropiperine and 1 part of eucalyptol" in step (4) is replaced with "1.12 parts of tetrahydropiperine".

[0056] Comparative Example 5 The difference between this comparative example and Example 1 is that "0.12 parts of tetrahydropiperine and 1 part of eucalyptol" in step (4) is replaced with "1.12 parts of eucalyptol".

[0057] Comparative Example 6 The difference between this comparative example and Example 1 is that polyvinyl alcohol 1788 is replaced with sodium alginate.

[0058] Comparative Example 7 The difference between this comparative example and Example 1 is that the polyether-modified polysiloxane is replaced with fatty alcohol polyoxyethylene ether-9, and the propylene glycol alginate is replaced with Tween-80.

[0059] Experimental Example 1 The snail control effect of the sprays prepared in Examples 1-3 and Comparative Examples 1-7 under rainwater scouring conditions was tested, as well as the persistence and scouring resistance of the sprays.

[0060] Test snails: Healthy gray snails weighing 1.3±0.2g were selected and starved for 24 hours.

[0061] Test plants: uniformly growing, disease-free Chinese cabbage plants, potted, 3 plants per pot.

[0062] Test reagents: Spraying agents prepared in Examples 1-3 and Comparative Examples 1-7.

[0063] Control treatments: water (blank control), insecticide spray (active ingredient 0.5% fipronil, brand name: Quercetin, pesticide registration certificate number WP20180126, positive control).

[0064] The study set up two main groups: no rain and rain. Each main group was further divided into 12 subgroups, with 3 replicates in each subgroup and 3 pots of bok choy in each replicate.

[0065] The grouping is shown in Table 1.

[0066] Table 1 Grouping and Group Numbers

[0067] For the two groups, one with no rain and one with rain, spray each sprayer evenly on both sides of the bok choy leaves, stems, and the soil around the roots, until the leaves are moist but not dripping wet, and let them air dry naturally for 2 hours.

[0068] In the non-raining group, 20 gray snails that have been starved were placed in each pot, and the pot opening was covered with gauze to prevent them from escaping.

[0069] After the large group of snails were allowed to air dry for 2 hours, a simulated rain generator was used to continuously spray them with a rainfall intensity of 30 mm / h for 15 minutes, followed by 1 hour of air drying. Twenty starved gray snails were placed in each pot, and the pot opening was covered with gauze to prevent escape.

[0070] Observe and record the number of surviving snails at 24h and 48h respectively (no reaction in antennae or feet is considered as death), count the number of surviving snails in each group, calculate the average value, and calculate the corrected control effect.

[0071] Corrected control effect (%) = [(CK1 survival count - treatment group survival count) ÷ CK1 survival count] × 100%.

[0072] Table 2 Corrective and preventive effects of spraying agents in the no-rainfall group

[0073] Table 3. Corrective and preventive effects of different groups of sprayed agents for rainfall control

[0074] Overall, the rain-affected group experienced some loss of effective ingredients due to rainwater erosion, resulting in lower efficacy than the non-rain-affected group. In Examples 1-3, the snail control efficacy was close to that of the positive control group under non-rain-affected conditions, while it maintained a high efficacy under rain-affected conditions, indicating that the spray agent of this invention has the effect of resisting rainwater erosion.

[0075] As shown in Tables 2 and 3, the replacement of macroporous adsorption resin and the change of extraction solvent in Comparative Examples 1-3 led to a decrease in the purity of the active ingredients in the plant extracts, thus reducing the efficacy of the spray. Comparative Examples 4 and 5 used only a single penetration enhancer, resulting in reduced efficacy of the spray, indicating a synergistic effect between tetrahydropiperine and eucalyptol. Tetrahydropiperine disrupts the mucus barrier and promotes penetration, while eucalyptol reduces surface tension and enhances the penetration of snail mucus, jointly increasing the rate and dosage of active ingredients entering the snail's body. In Comparative Examples 6 and 7, replacing the additives with film-forming agents and surfactants resulted in decreased dispersion and spreadability, and reduced efficacy, indicating that optimizing the additives and extraction process is key to maintaining high activity.

[0076] The above data shows that the spray agent of this invention, with its triple combination of Ginkgo biloba extract, Psoralea corylifolia fruit extract, and Hedyotis diffusa extract, achieves multi-target killing by disrupting the mucus barrier, inhibiting cholinesterase, and damaging soft tissues. At the same time, tetrahydropiperine and eucalyptol synergistically promote penetration and improve penetration efficiency. Furthermore, through the inclusion step and the addition of film-forming agents, it significantly improves rain resistance and persistence while ensuring high insecticidal efficiency.

[0077] 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 spray agent for controlling snails, characterized in that, The raw materials include the following parts by weight: 1-3 parts Ginkgo biloba leaf extract, 0.5-1 part Psoralea corylifolia fruit extract, 0.8-1.2 parts Hedyotis diffusa extract, 1-2 parts modified chitosan, 0.5-1.5 parts hydroxypropyl-β-cyclodextrin, 0.1-0.15 parts tetrahydropiperine, 0.8-1.2 parts eucalyptol, 0.8-1.2 parts polyvinyl alcohol 1788, 1.5-2.3 parts surfactant, 0.8-1.5 parts dispersant, and 150-180 parts water.

2. The spraying agent according to claim 1, characterized in that, The preparation method of the ginkgo leaf extract includes: pulverizing ginkgo leaves, mixing with a solvent, heating and reflux extraction, filtering, and purifying the filtrate with macroporous resin to obtain the ginkgo leaf extract; the solvent is composed of an ethanol solution with a volume fraction of 83%-88% and an ethyl acetate solution with a volume fraction of 3%-7% in a volume ratio of 1:(1-3); the heating and reflux extraction temperature is 75-80℃, the extraction is performed 1-3 times, and each extraction lasts 1-3 hours.

3. The spraying agent according to claim 2, characterized in that, The macroporous adsorption resin is AB-8 type macroporous adsorption resin.

4. The spraying agent according to claim 1, characterized in that, The preparation method of the Psoralea corylifolia fruit extract includes: pulverizing Psoralea corylifolia fruit, enzymatically hydrolyzing it with a compound enzyme, adding methanol for ultrasonic extraction, centrifuging, concentrating the supernatant, and drying it to obtain the Psoralea corylifolia fruit extract.

5. The spraying agent according to claim 4, characterized in that, The complex enzyme is composed of cellulase and pectinase in a mass ratio of (4-6):(2-4); the ultrasonic extraction temperature is 37-42℃, the frequency is 20-30kHz, and the time is 25-35min.

6. The spraying agent according to claim 1, characterized in that, The preparation method of the *Hedyotis diffusa* extract includes: crushing the roots of *Hedyotis diffusa*, mixing them with a 75%-85% ethanol solution (by volume), treating them with a high-voltage pulsed electric field, performing microwave extraction, filtering, concentrating the filtrate, and drying to obtain the *Hedyotis diffusa* extract; the electric field strength of the high-voltage pulsed electric field treatment is 15-20 kV / cm, the pulse width is 20-30 μs, and the number of pulses is 8-12.

7. The spraying agent according to claim 6, characterized in that, The microwave extraction temperature is 50-55℃, the power is 200-250W, and the time is 5-10min.

8. The spraying agent according to claim 1, characterized in that, The surfactant comprises polyether-modified polysiloxane and propylene glycol alginate; the dispersant comprises sodium lignosulfonate and polycarboxylate.

9. A method for preparing a spraying agent according to any one of claims 1-8, characterized in that, include: Hydroxypropyl-β-cyclodextrin was mixed with 30-35 parts of water, then mixed with Ginkgo biloba extract, Psoralea corylifolia fruit extract, Gynostemma pentaphyllum extract, tetrahydropiperine, and eucalyptol. After ultrasonic treatment, a cyclodextrin inclusion complex solution was obtained. Modified chitosan was mixed with 15-20 parts of water, then mixed with the cyclodextrin inclusion complex solution and stirred to obtain an encapsulation mixture. Polyvinyl alcohol 1788 was mixed with 10-15 parts of water and heated to obtain a polyvinyl alcohol solution. The remaining water, surfactant, and dispersant were mixed to obtain a dispersion. The dispersion, encapsulation mixture, and polyvinyl alcohol solution were mixed and homogenized to obtain a spray agent.

10. The application of a spraying agent according to any one of claims 1-8 in the preparation of snail control products.

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