Environment-friendly multifunctional film spreading agent and preparation method and application thereof

Abstract

This invention discloses an environmentally friendly, multifunctional spreading agent, its preparation method, and its application. The spreading agent consists of a plant-derived base oil, a composite film-forming system, a natural surfactant, and a synergist. The mass percentages of each component are: plant-derived base oil 40%-65%, composite film-forming system 15%-30%, natural surfactant 5%-15%, synergist 2%-8%, and the remainder is an environmentally friendly solvent. This spreading agent contains no chemical pesticide components and achieves targeted biological control through physical sealing and interfacial tension regulation. It features rapid spreading speed, large coverage area, long-lasting effect, and environmental friendliness. This spreading agent can quickly form a uniform and dense oil film on the water surface, effectively killing aquatic pests such as schistosomiasis cercariae and mosquito larvae. It also has an auxiliary control effect on pests and diseases of aquatic crops such as rice and water chestnuts.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection and biological control technology, specifically involving an environmentally friendly multifunctional spreading agent and its preparation method and application, which is particularly suitable for killing aquatic pests such as schistosome cercariae and mosquito larvae, as well as for the ecological control of diseases and pests of aquatic crops. Background Technology

[0002] Spreading oils, as a highly efficient and labor-saving formulation, offer significant advantages in the control of aquatic pests due to their ability to be applied directly without dilution and to form a rapid film. Traditional spreading oils often rely on chemical pesticide components (such as deltamethrin and niclosamide), which can lead to environmental residues, toxicity to non-target organisms, and resistance in target organisms. Some pesticide-free spreading oils, on the other hand, suffer from poor film-forming stability, poor spreading performance, and short-lasting effects.

[0003] While existing chemical pesticide-based spreading agents offer significant control effects, they pose potential risks to aquatic ecosystems. Environmentally friendly spreading agents, on the other hand, often suffer from limitations such as single-function limitations and limited control efficacy. For example, some organosilicon-based spreading agents, while effective against mosquito larvae, have not been fully validated for their control of schistosome cercariae, and the film formed is easily ruptured by water flow. Therefore, developing a spreading agent that is highly effective, environmentally friendly, and multifunctional is of significant practical importance. Summary of the Invention

[0004] The core objective of this invention is to provide an environmentally friendly, multifunctional spreading agent, its preparation method, and its application. The spreading agent of this invention uses all-natural or environmentally friendly components, is free of chemical pesticides and highly toxic solvents, has a biodegradability rate of ≥90%, and exhibits extremely low toxicity to non-target organisms such as fish. At a concentration of 10 μL / L, the survival rate reaches 100% after 7 days, which is significantly superior to traditional chemical spreading agents.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An environmentally friendly, multifunctional film-forming agent is composed of the following components by weight percentage: 40%-65% plant-derived base oil, 15%-30% composite film-forming system, 5%-15% natural surfactant, 2%-8% synergist, and 3%-12% environmentally friendly solvent; the composite film-forming system is composed of dodecyl alcohol ester, methyl laurate, and polyglycerol fatty acid ester in a weight ratio of (2-4):(3-5):(1-2); the plant-derived base oil is selected from one or more of linseed oil, perilla seed oil, and tea seed oil; the natural surfactant is selected from one or more of saponin, tea saponin, and lecithin; the synergist is selected from one or more of limonene, eucalyptol, and menthol; and the environmentally friendly solvent is selected from one or more of ethanol, propylene glycol, and polyethylene glycol 400.

[0007] Furthermore, the preferred mass percentages of each component are: 50%-60% plant-derived base oil, 20%-25% composite film-forming system, 8%-12% natural surfactant, 3%-6% synergist, and 5%-10% environmentally friendly solvent.

[0008] Furthermore, the mass ratio of dodecyl alcohol ester, methyl laurate, and polyglycerol fatty acid ester in the composite film-forming system is 3:4:1.5.

[0009] Furthermore, the plant-derived base oil is a mixture of flaxseed oil and tea seed oil in a mass ratio of 1:1; the natural surfactant is a mixture of tea saponin and lecithin in a mass ratio of 2:1; and the synergist is a mixture of limonene and eucalyptol in a mass ratio of 3:2.

[0010] This invention also provides a method for preparing an environmentally friendly multifunctional film-forming agent, comprising the following steps: (1) Pretreatment: the plant-derived base oil is vacuum dehydrated at 45-55℃ for 30-40 min, and the water content is controlled below 0.5%; (2) Preparation of composite film-forming system: dodecyl alcohol ester, methyl laurate and polyglycerol fatty acid ester are weighed according to the proportion, and stirred and mixed at 60-70℃ and 80-120 rpm for 20-30 min, and cooled to room temperature for later use; (3) Mixing of main agent: the pre- The treated plant-derived base oil is added to the reaction vessel, and natural surfactants and environmentally friendly solvents are added in sequence. The mixture is stirred for 40-60 minutes at 35-45℃ and 150-200 rpm until the system is transparent and uniform. (4) Enhancement and compounding: The composite film-forming system and enhancer are added, and the mixture is stirred for 30-45 minutes at 30-40℃ and 100-150 rpm. (5) Post-treatment: The mixture is filtered through a 5μm filter membrane. After passing the test, the environmentally friendly multifunctional film spreading agent is obtained.

[0011] Furthermore, the vacuum degree in step (1) is 0.08-0.1MPa; the detection indicators in step (5) include: surface tension 22-26mN / m, oil / water interface tension 0.12-0.22mN / m, and spreading speed ≥8.0cm / s.

[0012] This invention also provides the application of an environmentally friendly, multifunctional film-spreading agent for killing schistosomiasis cercariae and mosquito larvae (wrigglers) in water, or for preventing and controlling diseases and pests of aquatic crops such as rice, water chestnuts, and lotus roots.

[0013] Furthermore, when using it, apply it to the surface of the water at a dose of 0.8-1.2 mL / m², and it will naturally diffuse to form a film with a thickness of 0.8-1.2 μm.

[0014] Furthermore, in the control of schistosomiasis cercariae, the mortality rate of cercariae is ≥95% 5 minutes after application and 100% 10 minutes after application; in the control of mosquito larvae, the mortality rate of larvae is 100% 24 hours after application, and the effective period is 15-20 days.

[0015] Furthermore, in the control of rice diseases and pests, the control effect on rice planthoppers, rice stem borers and sheath blight was ≥85% 14 days after application.

[0016] The present invention has the following beneficial effects:

[0017] This invention's film-forming agent uses all-natural or environmentally friendly components, free of chemical pesticides and highly toxic solvents, with a biodegradability rate ≥90%. It exhibits extremely low toxicity to non-target organisms such as fish, achieving a 100% survival rate after 7 days at a concentration of 10 μL / L, significantly superior to traditional chemical film-forming agents. The composite film-forming system works synergistically, achieving a spreading speed ≥8.0 cm / s, an expansion area ≥2300 cm² / 3.6 μL, strong post-film stability, no cracking or delamination within 15 days, and a long-lasting effect of 15-20 days. It also contains schistosome-resistant agents. It has functions of killing cercariae, controlling mosquito larvae, and controlling pests and diseases in aquatic crops. 14 days after application, the control effect on various targets is ≥85%, which is better than conventional spraying methods. No dilution with water or special application equipment is required. It can be directly dripped according to the area. The application time is ≤10 minutes per acre, which is more than 20 times more efficient than traditional spraying. It can be applied to various scenarios such as static water bodies (fish ponds, paddy fields, water-filled containers) and dynamic water bodies (ditches, shallow water areas of rivers). It has no phytotoxicity to aquatic crops such as rice, water chestnuts, and lotus roots. Detailed Implementation

[0018] The core of this invention lies in constructing a ternary system of plant-derived substrate, composite film formation, and natural synergist, achieving a comprehensive effect of physical sealing, interface regulation, and enhanced bioactivity through the synergistic effect of each component. The selection criteria for each component are as follows:

[0019] Plant-derived base oils: Selected natural plant oils such as flaxseed oil, perilla seed oil, and tea seed oil, which have good biocompatibility and degradability, while their unsaturated fatty acid structure can enhance the extensibility and stability of the membrane.

[0020] Composite film-forming system: It adopts a compound of dodecyl alcohol ester (film-forming core), methyl laurate (spreading promoter) and polyglycerol fatty acid ester (film stability enhancement) to solve the problem that it is difficult to achieve both the spreading speed and film stability of a single film-forming agent.

[0021] Natural surfactants: Select natural products such as saponins, tea saponins, and lecithin to reduce the surface tension of the system, promote the rapid diffusion of the spreading agent on the water surface, and enhance the effect on target organisms.

[0022] Synergists: Plant essential oils such as limonene and eucalyptol not only have certain biological activities, but also enhance the volatility and permeability of the membrane, thereby improving the physical sealing effect.

[0023] Environmentally friendly solvents: Low-toxicity solvents such as ethanol and propylene glycol are selected to ensure that all components are fully dissolved while reducing the environmental burden.

[0024] Specifically, this invention provides an environmentally friendly, multifunctional film-forming agent, composed of the following components by weight percentage: 40%-65% plant-derived base oil, 15%-30% composite film-forming system, 5%-15% natural surfactant, 2%-8% synergist, and 3%-12% environmentally friendly solvent. The composite film-forming system is composed of dodecyl alcohol ester, methyl laurate, and polyglycerol fatty acid ester in a weight ratio of (2-4):(3-5):(1-2). The plant-derived base oil is selected from one or more of linseed oil, perilla seed oil, and tea seed oil. The natural surfactant is selected from one or more of saponins, tea saponins, and lecithin. The synergist is selected from one or more of limonene, eucalyptol, and menthol. The environmentally friendly solvent is selected from one or more of ethanol, propylene glycol, and polyethylene glycol 400. This formulation, through the compounding of natural components, avoids chemical pesticide pollution. Simultaneously, the synergistic effect of each component ensures the spreadability, stability, and bioactivity of the film-forming agent, achieving highly efficient control of various target organisms.

[0025] In the preferred embodiment, the preferred mass percentages of each component are: 50%-60% plant-derived base oil, 20%-25% composite film-forming system, 8%-12% natural surfactant, 3%-6% synergist, and 5%-10% environmentally friendly solvent. The optimized proportions further enhance the synergistic effect of the components, ensuring the killing effect and duration of efficacy while reducing raw material costs and environmental impact.

[0026] In a preferred embodiment, the mass ratio of dodecyl alcohol ester, methyl laurate, and polyglycerol fatty acid ester in the composite film-forming system is 3:4:1.5. This specific ratio gives the film-forming system both rapid spreadability and stable toughness, resulting in a dense and uniform film that is not easily broken, thus prolonging the physical sealing and biological interaction time.

[0027] In a preferred embodiment, the plant-derived base oil is a mixture of linseed oil and tea seed oil in a 1:1 mass ratio; the natural surfactant is a mixture of tea saponin and lecithin in a 2:1 mass ratio; and the synergist is a mixture of limonene and eucalyptol in a 3:2 mass ratio. The mixed base oil improves carrier compatibility, the compound surfactant significantly reduces surface tension in water, and the compound synergist enhances the physiological inhibitory effect on target organisms; all three work synergistically to improve the overall control effect.

[0028] This invention also provides a method for preparing an environmentally friendly multifunctional film-forming agent, comprising the following steps: (1) Pretreatment: the plant-derived base oil is vacuum dehydrated at 45-55℃ for 30-40 min, and the water content is controlled below 0.5%; (2) Preparation of composite film-forming system: dodecyl alcohol ester, methyl laurate and polyglycerol fatty acid ester are weighed according to the proportion, and stirred and mixed at 60-70℃ and 80-120 rpm for 20-30 min, and cooled to room temperature for later use; (3) Mixing of main agent: the pre- The treated plant-derived base oil is added to the reactor, and natural surfactants and environmentally friendly solvents are added in sequence. The mixture is stirred at 35-45℃ and 150-200rpm for 40-60min until the system is transparent and homogeneous; (4) Enhancement and compounding: The composite film-forming system and enhancer are added, and the mixture is stirred at 30-40℃ and 100-150rpm for 30-45min; (5) Post-treatment: The mixture is filtered through a 5μm filter membrane. After passing the test, the environmentally friendly multifunctional film-forming agent is obtained. The step-by-step preparation process ensures that the components are fully integrated and avoids uneven local concentration. Vacuum dehydration and filtration improve the stability of the product and reduce the impact of impurities on the film-forming performance and bioactivity.

[0029] In the preferred embodiment, the vacuum degree in step (1) is 0.08-0.1 MPa; the detection indicators in step (5) include: surface tension 22-26 mN / m, oil / water interfacial tension 0.12-0.22 mN / m, and spreading speed ≥8.0 cm / s. The specific vacuum degree ensures that the base oil is thoroughly dehydrated, avoiding the influence of moisture on the film-forming effect; the clear detection indicators ensure the consistency of product quality and ensure that the spreading agent can spread quickly and play its role in different water environments.

[0030] This invention also provides applications for an environmentally friendly, multifunctional film-spreading agent, used to kill schistosome cercariae and mosquito larvae (wrigglers) in water, or to control pests and diseases in aquatic crops such as rice, water chestnuts, and lotus roots. This achieves multiple uses with a single agent, broadens application scenarios, reduces the number of pesticides needed for different control requirements, and lowers usage costs and environmental impact.

[0031] In a preferred embodiment, the solution is applied dropwise to the water surface at a dose of 0.8-1.2 mL / m², allowing it to naturally diffuse and form a film with a thickness of 0.8-1.2 μm. This dosage and film thickness ensure effective coverage and intensity of action on the target organisms while avoiding resource waste and environmental residue caused by excessive dosage.

[0032] In the preferred embodiment, in the control of schistosomiasis cercariae, the cercariae mortality rate is ≥95% within 5 minutes after application and 100% within 10 minutes; in the control of mosquito larvae, the larval mortality rate is 100% within 24 hours after application, with a residual effect of 15-20 days. The rapid killing effect meets the needs of emergency control, and the long residual effect reduces the frequency of application, improves control efficiency, and lowers labor costs.

[0033] In the preferred embodiment, the control efficacy against rice planthoppers, rice stem borers, and sheath blight is ≥85% 14 days after application. The control effect is stable and long-lasting, meeting the long-term pest and disease control needs in agricultural production, reducing the amount of chemical pesticides used, and ensuring crop quality and ecological safety.

[0034] The following examples are provided to further illustrate the present invention, but do not limit the scope of protection of the present invention. All components in each example are expressed as a percentage by mass.

[0035] Example 1: An environmentally friendly multifunctional spreading agent, composed of the following components by weight percentage:

[0036] Plant-derived base oils: 30% flaxseed oil + 30% camellia seed oil;

[0037] Composite film-forming system: 6% dodecyl alcohol ester + 8% methyl laurate + 3% polyglycerol fatty acid ester;

[0038] Natural surfactants: 6% tea saponin + 3% lecithin;

[0039] Synergist: 3% limonene + 2% eucalyptol;

[0040] Environmentally friendly solvent: 5% ethanol + 2% propylene glycol;

[0041] Example 2, an environmentally friendly multifunctional spreading agent, composed of the following components by weight percentage:

[0042] Plant-derived base oil: Perilla seed oil 55%;

[0043] Composite film-forming system: 5% dodecyl alcohol ester + 7% methyl laurate + 2% polyglycerol fatty acid ester;

[0044] Natural surfactant: 10% saponin;

[0045] Synergist: Menthol 4%;

[0046] Environmentally friendly solvent: 400% polyethylene glycol + 10% ethanol;

[0047] Example 3, an environmentally friendly multifunctional spreading agent, composed of the following components by weight percentage:

[0048] Plant-derived base oil: 25% flaxseed oil + 25% perilla seed oil;

[0049] Composite film-forming system: 8% dodecyl alcohol ester + 10% methyl laurate + 4% polyglycerol fatty acid ester;

[0050] Natural surfactants: 5% tea saponin + 3% lecithin;

[0051] Synergist: 2% limonene + 2% menthol;

[0052] Environmentally friendly solvent: 6% propylene glycol + 4% ethanol;

[0053] In this invention, the preparation method of an environmentally friendly multifunctional spreading agent in Examples 1-3 includes the following steps: The preparation method of the spreading agent of this invention adopts a stepwise composite process to ensure that each component is fully integrated. The specific steps are as follows: (1) Pretreatment: Add the plant-derived base oil to a vacuum dehydration device and dehydrate it for 30-40 minutes at 45-55℃ and 0.08-0.1MPa until the water content is ≤0.5%. Cool it to room temperature for later use; (2) Preparation of composite film-forming system: Weigh dodecyl alcohol ester, methyl laurate and polyglycerol fatty acid ester according to the proportion, add them to a stirring tank, and stir and mix them for 20-30 minutes at 60-70℃ and 80-120rpm to form a uniform and transparent composite system. Cool it to room temperature for later use. Room temperature; (3) Mixing of main agents: Add the pretreated plant-derived base oil to the reactor, add natural surfactants and environmentally friendly solvents in sequence, stir at 35-45℃ and 150-200rpm for 40-60min, take samples every 10min during the period, until the system is completely transparent and without layering; (4) Synergistic compounding: Add the cooled composite film-forming system and synergist to the reactor, adjust the temperature to 30-40℃, reduce the speed to 100-150rpm, continue stirring for 30-45min to ensure that each component is fully synergistic; (5) Post-treatment: Filter the mixture through a 5μm precision filter membrane to remove trace impurities, test the surface tension, interfacial tension, spreading speed and other indicators, and after passing the test, package to obtain the finished product.

[0054] Examples 1-3, Technical Performance Testing:

[0055] The core technical indicators of the spreading agents prepared in Examples 1-3 were tested, and traditional chemical spreading agents (containing 0.5% deltamethrin) and single film-forming agents (dodecyl ester) were used as controls. The results are shown in Table 1 below:

[0056] Table 1 detection indicators Example 1 Example 2 Example 3 Traditional comparison Single film-forming agent control Surface tension (35℃, mN / m) 23.5 24.8 22.9 27.3 28.6 Oil / water interfacial tension (mN / m) 0.15 0.18 0.14 0.25 0.31 Spreading speed (cm / s) 8.7 8.2 9.1 7.5 6.8 Expanded area (cm² / 3.6μL) 2468 2352 2513 2145 1876 Film formation stability (15 days) No cracks No cracks No cracks Localized rupture Severe rupture Thermal storage stability (54℃±2℃, 14d) No sedimentation or layering No sedimentation or layering No sedimentation or layering Slight sedimentation Layering Low temperature stability (0℃±2℃, 7d) No crystallization or precipitation No crystallization or precipitation No crystallization or precipitation Small amount of crystals Clear crystallization

[0057] To verify the application effect of the film-spreading agent of this invention, bioactivity test data were conducted, including schistosomiasis cercariae killing test, mosquito larvae control test, aquatic crop pest and disease control test, and ecological safety test. The specific results are shown in Table 2.

[0058] Schistosoma cercariae killing test: Test conditions: 25℃ laboratory environment, 6-well culture plate, 2mL of dechlorinated water and 30 freshly escaped Schistosoma japonicum cercariae were added to each well, and the spreading agent was added at a dose of 1.0mL / m². The mortality rate of cercariae was observed at different time points.

[0059] Table 2 experimental group 1-minute mortality rate (%) 3-minute mortality rate (%) 5-minute mortality rate (%) 10-minute mortality rate (%) 30-minute mortality rate (%) Example 1 68.3 89.7 96.5 100 100 Example 2 62.5 85.3 94.2 100 100 Example 3 71.4 92.6 97.8 100 100 Traditional chemical spreading agents 75.2 93.1 98.4 100 100 Blank control (dechlorinated water) 0 0 0 0 0

[0060] Mosquito larvae (wrigglers) control experiment: Experimental conditions: Simulated outdoor waterlogged environment, plastic bucket (volume 10L, water surface area 0.1m²), 8L tap water and 100 third-instar larvae were added to each bucket, and the film agent was applied at a dosage of 1.0mL / m². The mortality rate and duration of effectiveness were observed regularly, as shown in Table 3.

[0061] Table 3 experimental group 24-hour mortality rate (%) 7-day mortality rate (%) 14-day mortality rate (%) 20-day mortality rate (%) Shelf life (days) Example 1 100 100 98.5 82.3 18 Example 2 100 99.2 96.8 78.5 16 Example 3 100 100 99.1 85.7 19 Traditional chemical spreading agents 100 100 97.6 80.2 15 Blank control 0 5.3 12.6 21.4 -

[0062] Experiment on the control of diseases and pests of aquatic crops: Experimental sites: paddy fields in Nanning, Guangxi (rice planthopper, rice stem borer, sheath blight) and water chestnut fields in Beihai, Guangxi (water chestnut white rice stem borer). The control effect was investigated regularly at a dose of 1.0 mL / m², as shown in Table 4.

[0063] Table 4 Target of prevention and control experimental group 3 days after medication, the preventive effect (%) 7-day efficacy (%) after medication Efficacy (%) 14 days after administration Rice planthoppers Example 1 69.4 78.6 87.5 Example 3 71.2 80.3 89.2 Traditional spray 48.5 59.3 72.6 Rice stem borer Example 1 66.8 75.4 86.3 Example 2 64.3 73.2 84.7 Traditional spray 46.2 55.1 63.8 Rice sheath blight Example 2 65.7 74.9 88.6 Example 3 68.4 77.2 90.3 Traditional spray 47.6 56.4 66.2 Water chestnuts and white rice moths Example 1 70.5 82.3 91.7 Example 3 72.8 84.5 93.2 Traditional spray 57.3 65.4 79.6

[0064] Ecological safety test: Medaka (international standard test fish) was selected as a non-target organism, and exposure tests of film-spreading agents with different concentration gradients were set up to observe the survival rate for 7 days, as shown in Table 5.

[0065] Table 5 Exposure concentration (μL / L) Example 17-day survival rate (%) Example 37-day survival rate (%) Survival rate (%) of traditional chemical spreading agents after 7 days 1 100 100 100 10 100 100 90 100 95 92 65 500 82 78 30

[0066] Application Implementation Method 1: Control of Schistosoma cercariae:

[0067] In susceptible water bodies (such as fishponds, ditches, and paddy fields) in schistosomiasis endemic areas, the film-spreading agent of this invention (Example 1) is applied directly to the water surface at a dose of 1.0 mL / m² without stirring. After application, the film-spreading agent rapidly spreads into a film within 30 seconds, with a cercariae mortality rate of ≥95% within 5 minutes and 100% kill within 10 minutes. For dynamic water bodies, application points can be set up upstream and downstream at 50-meter intervals to ensure the entire water surface is covered with a film, effectively blocking the infection of schistosomiasis cercariae to humans and animals during the effective period.

[0068] Application Implementation Method 2: Prevention and Control of Mosquito-borne Infectious Diseases

[0069] In mosquito breeding water bodies (such as rainwater wells, collection wells, and water-collecting containers) in dengue fever and malaria endemic areas, the spreading agent of this invention is applied by dripping at a dosage of 0.8 mL / m² (Example 2). The mosquito larvae mortality rate is 100% within 24 hours of application, and the effect lasts for 16 days, during which time it effectively inhibits the hatching of new eggs. In complex environments such as septic tanks and sewage wells, the spreading agent can form a tensile film with floating objects; even if gas is generated, the integrity of the film will not be damaged, ensuring the control effect.

[0070] Application Implementation Method 3: Control of Diseases and Pests in Aquatic Crops

[0071] In rice fields where rice planthoppers, rice stem borers, and sheath blight occur together during the tillering to jointing stages, the film-spreading agent of this invention is applied by drip irrigation at a dose of 1.2 mL / m² (Example 3). The film spreads upwards along the rice stem, concentrating at the base of the stem. 14 days after application, the control efficacy against rice planthoppers is 89.2%, against rice stem borers is 84.7%, and against sheath blight is 90.3%, with no adverse effects on rice growth. This reduces the amount of conventional pesticides used by more than 60%.

[0072] Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art, all of which fall within the protection scope of this invention.

Claims

1. An environmentally friendly, multifunctional spreading agent, characterized in that, It is composed of the following components by mass percentage: 40%-65% plant-derived base oil, 15%-30% composite film-forming system, 5%-15% natural surfactant, 2%-8% synergist, and 3%-12% environmentally friendly solvent; the composite film-forming system is composed of dodecyl alcohol ester, methyl laurate, and polyglycerol fatty acid ester in a mass ratio of (2-4):(3-5):(1-2); the plant-derived base oil is selected from one or more of linseed oil, perilla seed oil, and tea seed oil; the natural surfactant is selected from one or more of saponin, tea saponin, and lecithin; the synergist is selected from one or more of limonene, eucalyptol, and menthol; and the environmentally friendly solvent is selected from one or more of ethanol, propylene glycol, and polyethylene glycol 400.

2. The environmentally friendly multifunctional spreading agent according to claim 1, characterized in that, The preferred percentages of each component by mass are: 50%-60% plant-derived base oil, 20%-25% composite film-forming system, 8%-12% natural surfactant, 3%-6% synergist, and 5%-10% environmentally friendly solvent.

3. The environmentally friendly multifunctional spreading agent according to claim 1, characterized in that, The mass ratio of dodecyl alcohol ester, methyl laurate and polyglycerol fatty acid ester in the composite film-forming system is 3:4:1.

5.

4. The environmentally friendly multifunctional spreading agent according to claim 1, characterized in that, The plant-derived base oil is a mixture of flaxseed oil and tea seed oil in a mass ratio of 1:1; the natural surfactant is a mixture of tea saponin and lecithin in a mass ratio of 2:1; and the synergist is a mixture of limonene and eucalyptol in a mass ratio of 3:

2.

5. A method for preparing an environmentally friendly multifunctional spreading agent as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Pretreatment: Dehydrate the plant-derived base oil under vacuum at 45-55℃ for 30-40 min, and control the water content to below 0.5%; (2) Preparation of composite film-forming system: Weigh dodecyl alcohol ester, methyl laurate and polyglycerol fatty acid ester according to the proportion, stir and mix at 60-70℃ and 80-120 rpm for 20-30 min, and cool to room temperature for later use; (3) Mixing of main agent: Add the pretreated plant-derived base oil to the reaction vessel, add natural surfactant and environmentally friendly solvent in sequence, stir at 35-45℃ and 150-200 rpm for 40-60 min until the system is transparent and uniform; (4) Synergistic compounding: Add composite film-forming system and synergist, stir at 30-40℃ and 100-150 rpm for 30-45 min; (5) Posttreatment: Filter the mixture through a 5μm filter membrane, and after passing the test, the environmentally friendly multifunctional film-forming agent is obtained.

6. The preparation method according to claim 5, characterized in that, In step (1), the vacuum degree is 0.08-0.1MPa; in step (5), the test indicators include: surface tension 22-26mN / m, oil / water interface tension 0.12-0.22mN / m, and spreading speed ≥8.0cm / s.

7. An application of the environmentally friendly multifunctional spreading agent as described in any one of claims 1-4, characterized in that, It is used to kill schistosome cercariae and mosquito larvae in water, or to control pests and diseases in aquatic crops such as rice, water chestnuts, and lotus roots.

8. The application according to claim 7, characterized in that, When using, apply the solution at a dose of 0.8-1.2 mL / m² to the surface of the water body. It will naturally diffuse to form a film with a thickness of 0.8-1.2 μm.

9. The application according to claim 7, characterized in that, In the control of schistosomiasis cercariae, the mortality rate of cercariae is ≥95% 5 minutes after application and 100% 10 minutes after application; in the control of mosquito larvae, the mortality rate of larvae is 100% 24 hours after application, and the effective period is 15-20 days.

10. The application according to claim 7, characterized in that, In the control of rice diseases and pests, the control effect on rice planthoppers, rice stem borers and sheath blight was ≥85% 14 days after application.