A low-toxicity and environment-friendly snail-killing composition containing a synergistic component and a preparation method thereof

Abstract

The application discloses a low-toxicity environment-friendly snail-killing composition containing a synergistic component and a preparation method thereof, and belongs to the technical field of pesticide preparations. The snail-killing composition comprises tetrapolyacetaldehyde, snail-killing amine, foxglove water extract freeze-dried powder, polyether modified trisiloxane, chitosan-sodium alginate microcapsules and an auxiliary agent. The application realizes high-efficiency prevention and control of the whole life cycle of golden apple snails, including adult snails, young snails and egg masses, by constructing a multi-element synergistic system of a microbial source quick-acting snail-killing protein, a plant source synergistic snail-killing component and a chemical synergist, and combining a microcapsule slow-release technology. The application also discloses a preparation method of the snail-killing composition. Compared with the prior art, the application has the advantages of high-efficiency snail killing, low toxicity, environmental protection, slow release, anti-scouring and synergistic effect.

Description

Technical Field

[0001] This invention relates to the field of pesticide formulation technology, specifically to a low-toxicity and environmentally friendly molluscicide composition containing synergistic components and its preparation method. Background Technology

[0002] Golden apple snails and Oncomelania hupensis are important aquatic snails that harm agricultural production and spread schistosomiasis, respectively. Golden apple snails, as an invasive species, have a diverse diet and high reproductive rate, causing serious damage to crops such as rice. Oncomelania hupensis, on the other hand, is the only intermediate host for schistosomiasis, and effectively controlling it is a key aspect of schistosomiasis prevention and control. Currently, chemical control remains the primary method for eliminating snails.

[0003] Existing molluscicides mainly suffer from the following technical problems: First, highly effective molluscicides, such as molluscicides like molluscicides, are extremely toxic to aquatic organisms, especially fish, and their large-scale use in the environment can easily cause water pollution and ecological damage. Second, low-toxicity molluscicides, such as metaldehyde, are not very effective when used alone, requiring higher doses to achieve acceptable control efficacy, resulting in higher costs and unstable effects. Third, while some plant-derived molluscicides, such as camel nut seed powder and oleander extract, have certain molluscicidal activity, they suffer from drawbacks such as slow toxicity, poor efficacy against adult snails, large fluctuations in the natural content of active ingredients, single formulation, and lack of functional adjuvants. Fourth, existing toxic agents targeting golden apple snail eggs are mostly single liquid formulations, not targeting adult or juvenile snails, and lack sustained-release and targeted delivery designs.

[0004] Therefore, developing a green molluscicide composition that combines rapid and long-lasting effects, is safe for non-target organisms, and has both sustained-release and targeted functions remains a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a low-toxicity and environmentally friendly molluscicide composition containing synergistic components and its preparation method. By constructing a multi-component synergistic system based on fast-acting microbial molluscicide proteins, plant-derived synergistic molluscicide components, and functional synergists, and combining it with microencapsulation sustained-release technology, a green molluscicide formulation with both fast-acting contact killing and long-acting sustained-release functions is prepared. This solves the technical problems of existing molluscicides, such as high toxicity to aquatic organisms, poor efficacy of low-toxicity agents, slow and unstable action of plant-derived components, and lack of sustained-release targeted design.

[0006] In a first aspect, the present invention provides a low-toxicity, environmentally friendly molluscicide composition containing synergistic components, comprising the following raw materials in parts by weight: Active ingredient group: 10-25 parts of metaldehyde; 5-15 parts of molluscicide; 3-15 parts of freeze-dried oleander water extract powder; Synergist group: 1-6 parts of polyether-modified trisiloxane; Sustained-release carrier group: Chitosan-sodium alginate microcapsules, 5-20 parts; Additives group: 2-5 parts dispersant; 0.5-2 parts wetting agent; 3-6 parts antifreeze; Thickener 0.1-0.5 parts; Defoamer 0.1-0.3 parts; Preservative: 0.1-0.3 parts; Add deionized water to bring the total to 100 parts.

[0007] As a preferred embodiment of the present invention, the dispersant is sodium lignosulfonate, the wetting agent is sodium dodecyl sulfate, the antifreeze is glycerol, the thickener is xanthan gum, the defoamer is an organosilicon defoamer, and the preservative is sodium benzoate.

[0008] As a preferred embodiment of the present invention, the mass ratio of metaldehyde to molluscicide is 18:10.

[0009] As a preferred technical solution of the present invention, the preparation method of the freeze-dried oleander water extract powder specifically includes the following steps: B1. Pulverize dried oleander leaves and pass them through a 60-mesh sieve to obtain oleander powder; B2. Mix the oleander powder obtained in step B1 with deionized water and extract it by stirring in a water bath at 70°C for 1.5 hours to obtain the extract mixture. The mass ratio of the oleander powder to deionized water is 1:10; B3. Filter the extract mixture obtained in step B2, collect the filtrate, and concentrate it to one-fifth of the original volume by rotary evaporation at 50°C to obtain the concentrate. B4. Freeze-dry the concentrated solution obtained in step B3 at -50℃ for 48 hours to obtain oleander water extract freeze-dried powder.

[0010] As a preferred embodiment of the present invention, the preparation method of the chitosan-sodium alginate microcapsules specifically includes the following steps: The preparation method of the chitosan-sodium alginate microcapsules specifically includes the following steps: C1. Chitosan is dissolved in a 0.5 wt% aqueous acetic acid solution to obtain a chitosan acetate solution; lyophilized oleander water extract powder is dissolved in the chitosan acetate solution to obtain an internal aqueous phase; The mass ratio of chitosan, 0.5wt% acetic acid aqueous solution and oleander water extract freeze-dried powder is 1:200:8; C2. Dissolve sodium alginate in deionized water, add Tween-80, and obtain the external aqueous phase; The mass ratio of sodium alginate, deionized water, and Tween-80 is 1:200:1; C3. Slowly drop the inner aqueous phase obtained in step C1 into the outer aqueous phase obtained in step C2, and stir at 1000 r / min for 15 min to obtain an emulsified mixture. C4. Add calcium chloride aqueous solution dropwise to the emulsion mixture obtained in step C3, continue stirring for 30 min, centrifuge to collect the precipitate, wash with deionized water, freeze dry at -50℃ to obtain chitosan-sodium alginate microcapsules. The calcium chloride aqueous solution has a mass fraction of 5%, and the volume ratio of the emulsified mixture to the calcium chloride aqueous solution is 20:1.

[0011] As a preferred embodiment of the present invention, the chitosan has a molecular weight of 50 kDa and a degree of deacetylation of 92%; the sodium alginate has a viscosity of 300 mPa·s.

[0012] It should be noted that the performance improvement of the low-toxicity and environmentally friendly molluscicide composition containing synergistic components provided by this invention stems from the synergistic design of the multi-component synergistic system and the functions of each component. Metaldehyde, as an attractant and contact killer, attracts golden apple snails and Oncomelania hupensis to feed, causing paralysis of the snail's nerves and excessive mucus secretion upon contact. Molluscicide, as a potent molluscicide, exerts a rapid lethal effect by inhibiting the uncoupling effect of mitochondrial oxidative phosphorylation. The combination of the two can maintain highly efficient molluscicide activity while reducing the dosage of molluscicide. The freeze-dried powder of oleander water extract contains rutin and oleandrin, which produce a synergistic lethal effect with metaldehyde and molluscicide, significantly improving the toxicity to adult golden apple snails and egg masses. Polyether-modified trisiloxane, as a synergist, has superior spreading and penetrating capabilities, significantly reducing the surface tension of the drug solution, promoting uniform coverage and adhesion of the drug solution on the snail's surface and plant stems, and simultaneously promoting the penetration of the active ingredient into the snail's cuticle. Chitosan-sodium alginate microcapsules encapsulate a portion of the lyophilized oleander water extract powder, forming a sustained-release reservoir. The unencapsulated active ingredient remains in free form, providing rapid contact toxicity. Together, they constitute a dual delivery system of rapid and sustained release, ensuring both rapid onset of action at the initial application and extended duration of effect. Simultaneously, the encapsulation protection enhances the active ingredient's resistance to rain washout. The synergistic effects of various adjuvants ensure the formulation's dispersibility, stability, wettability, and processability. Overall, this composition, through a triple synergistic mechanism of rapid, sustained, and synergistic action, effectively reduces the dosage of highly toxic molluscicides while achieving full life-cycle control of adult snails, juvenile snails, and snail eggs, with high safety for aquatic organisms, meeting green environmental protection requirements.

[0013] A second aspect of the present invention provides a method for preparing a low-toxicity, environmentally friendly molluscicide composition containing synergistic components, comprising the following steps: S1. Weigh out the following ingredients according to the formula: metaldehyde, molluscicide, lyophilized oleander water extract, dispersant, wetting agent, antifreeze agent, and 60-80% of the formula amount of deionized water. Add them to the mixing tank and mix at a stirring speed of 300-500 r / min for 20-30 min to obtain a premixed slurry. S2. The premixed slurry obtained in step S1 is fed to a high-speed shearing machine and sheared at 3000 r / min for 3-5 min to obtain a sheared mixture. S3. Pump the shear mixture obtained in step S2 into a horizontal sand mill, add zirconium oxide grinding media, and perform circulating grinding. Control the material temperature to be below 35℃ until the material particle size D90≤10μm, and obtain qualified ground material. S4. Transfer the qualified ground material obtained in step S3 to a mixing tank. Add thickener, defoamer and preservative in sequence under slow stirring at 200-400r / min. Stir and mix evenly to obtain the mixed material. S5. Under slow stirring at 200-400 r / min, slowly add polyether-modified trisiloxane to the mixture obtained in step S4. After the addition is complete, continue stirring for 30 min. Then add chitosan-sodium alginate microcapsules and homogenize at 1000 r / min for 2 min. Add the remaining deionized water to bring the total weight to 100 parts to obtain a low-toxicity and environmentally friendly molluscicide composition containing synergistic components.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention constructs a three-element synergistic molluscicide system with fast-acting, slow-acting and synergistic effects. It combines the chemical molluscicides metaldehyde and molluscicide with plant-derived oleander extract and chemical synergist polyether-modified trisiloxane. This reduces the amount of molluscicide used while achieving efficient control of the entire life cycle of adult snails, juvenile snails and egg masses of golden apple snails.

[0015] (2) The present invention uses self-assembled chitosan-sodium alginate microcapsules to encapsulate some microbial proteins and plant extracts, which together with free active ingredients form a dual delivery system, giving the formulation sustained release and rain erosion resistance, reducing the drug loss rate, extending the duration of effect, and effectively improving the problems of slow action, easy loss and instability of existing plant-derived molluscicides.

[0016] (3) The compound system of metaldehyde, molluscicide and oleander extract used in this invention achieves efficient molluscicide while the amount of molluscicide applied per unit area is much lower than that of traditional molluscicide single agent, significantly reducing the toxicity to non-target aquatic organisms such as fish and having excellent environmental compatibility.

[0017] (4) The preparation process provided by the present invention adopts a wet grinding and post-addition of synergists and microcapsules, which not only ensures the fineness requirements of the active ingredients, but also avoids the damage to the molecular structure of synergists and the morphology of microcapsules caused by high-speed shearing and high temperature. The process conditions are mild, the operation is simple, and it is easy to industrialize. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Preparation Example 1 The preparation method of lyophilized oleander water extract powder includes the following steps: B1. Pulverize dried oleander leaves and pass them through a 60-mesh sieve to obtain oleander powder; B2. Mix the oleander powder obtained in step B1 with deionized water and extract it by stirring in a water bath at 70°C for 1.5 hours to obtain the extract mixture. B3. Filter the extract mixture obtained in step B2 using three layers of gauze and filter paper, collect the filtrate, and concentrate it to one-fifth of the original volume by rotary evaporation at 50°C to obtain the concentrated solution. B4. Freeze-dry the concentrated solution obtained in step B3 at -50℃ for 48 hours to obtain oleander water extract freeze-dried powder. The mass ratio of the dried oleander leaf powder to deionized water is 1:10.

[0020] Preparation Example 2 The preparation method of the chitosan-sodium alginate microcapsules specifically includes the following steps: C1. Chitosan is dissolved in a 0.5 wt% aqueous acetic acid solution to obtain a chitosan acetic acid solution; the lyophilized powder of oleander water extract prepared in Preparation Example 1 is dissolved in the chitosan acetic acid solution to obtain an inner aqueous phase; The mass ratio of chitosan, 0.5wt% acetic acid aqueous solution and oleander water extract freeze-dried powder is 1:200:8; C2. Dissolve sodium alginate in deionized water, add Tween-80, and obtain the external aqueous phase; The mass ratio of sodium alginate, deionized water, and Tween-80 is 1:200:1; C3. Slowly drop the inner aqueous phase obtained in step C1 into the outer aqueous phase obtained in step C2, and stir at 1000 r / min for 15 min to obtain an emulsified mixture. C4. Add calcium chloride aqueous solution dropwise to the emulsion mixture obtained in step C3, continue stirring for 30 min, centrifuge to collect the precipitate, wash with deionized water, freeze dry at -50℃ to obtain chitosan-sodium alginate microcapsules. The calcium chloride aqueous solution has a mass fraction of 5%, and the volume ratio of the emulsified mixture to the calcium chloride aqueous solution is 20:1. Example

[0021] A low-toxicity, environmentally friendly molluscicide composition containing synergistic components, comprising the following raw materials in parts by weight: 25 parts of metaldehyde; 12.6 parts of molluscicide; 8 portions of freeze-dried oleander water extract powder; 3.5 parts of polyether-modified trisiloxane; 12 portions of chitosan-sodium alginate microcapsules; 3 parts sodium lignosulfonate; 1 part sodium dodecyl sulfate; 4 parts glycerol; 0.25 parts xanthan gum; 0.2 parts of silicone defoamer; Sodium benzoate 0.2 parts; Add deionized water to bring the total to 100 parts.

[0022] A method for preparing a low-toxicity, environmentally friendly molluscicide composition containing synergistic components includes the following steps: S1. Weigh out the following ingredients according to the formula: metaldehyde, molluscicide, freeze-dried oleander water extract powder prepared in Example 1, sodium lignosulfonate, sodium dodecyl sulfate, glycerol and 70 parts of deionized water, add them to the mixing tank, and mix at a stirring speed of 400 r / min for 25 min to obtain a premixed slurry. S2. The premixed slurry obtained in step S1 is fed to a high-speed shearing machine and sheared at 3000 r / min for 4 min to obtain a sheared mixture. S3. Pump the shear mixture obtained in step S2 into a horizontal sand mill, add zirconium oxide grinding media, and perform circulating grinding. Control the material temperature to be below 35℃ until the material particle size D90≤10μm, and obtain qualified ground material. S4. Transfer the qualified ground material obtained in step S3 to a mixing tank. Add xanthan gum, silicone defoamer and sodium benzoate in sequence under slow stirring at 300r / min. Stir and mix evenly to obtain the mixed material. S5. Under slow stirring at 300 r / min, polyether-modified trisiloxane is slowly added dropwise to the mixture obtained in step S4. After the addition is complete, stirring is continued for 30 min. Then, chitosan-sodium alginate microcapsules prepared in Preparation Example 2 are added, and homogenized at 1000 r / min for 2 min. The remaining deionized water is added to bring the total weight to 100 parts to obtain a low-toxicity and environmentally friendly molluscicide composition containing synergistic components.

[0023] In this embodiment, some of the raw materials used are the same as those obtained in Preparation Examples 1-2, and the other examples are the same. Example

[0024] A low-toxicity, environmentally friendly molluscicide composition containing synergistic components, comprising the following raw materials in parts by weight: 10 parts of metaldehyde; 5 parts of molluscicide; Three portions of freeze-dried oleander water extract powder; One part of polyether-modified trisiloxane; Five portions of chitosan-sodium alginate microcapsules; Sodium lignosulfonate, 2 parts; Sodium dodecyl sulfate 0.5 parts; 3 parts glycerol; 0.1 parts xanthan gum; 0.1 parts of silicone defoamer; Sodium benzoate 0.1 parts; Add deionized water to bring the total to 100 parts.

[0025] The preparation process is the same as in Example 1. Example

[0026] A low-toxicity, environmentally friendly molluscicide composition containing synergistic components, comprising the following raw materials in parts by weight: 25 parts of metaldehyde; 15 parts of molluscicide; 15 portions of freeze-dried oleander water extract powder; 6 parts of polyether-modified trisiloxane; 20 portions of chitosan-sodium alginate microcapsules; 5 parts sodium lignosulfonate; Two parts of sodium dodecyl sulfate; 6 parts glycerol; 0.5 parts xanthan gum; 0.3 parts of silicone defoamer; Sodium benzoate 0.3 parts; Add deionized water to bring the total to 100 parts.

[0027] The preparation process is the same as in Example 1.

[0028] Comparative Example 1 The difference between this comparative example and Example 1 is that the freeze-dried oleander water extract powder prepared in Example 1 was not added, but an equal amount of deionized water was used instead. The remaining components and preparation process are the same as in Example 1.

[0029] Comparative Example 2 The difference between this comparative example and Example 1 is that the chitosan-sodium alginate microcapsules prepared in Example 2 were not added; instead, an equal amount of deionized water was used instead. The remaining components and preparation process are the same as in Example 1.

[0030] Comparative Example 3 The difference between this comparative example and Example 1 is that no polyether-modified trisiloxane was added; the remaining components and preparation process are the same as in Example 1.

[0031] Comparative Example 4 The difference between this comparative example and Example 1 is that 50% molluscicide wettable powder was used as a control.

[0032] test: I. Test on the venom-killing effect of adult golden apple snails With a surface area of ​​approximately 1.0 m² 2 One hundred adult golden apple snails (7±0.5g) were placed in a plastic basin, and 1.5L of dechlorinated tap water (25-30℃) was added until the snails were just submerged. A perforated transparent plastic film was then used to prevent the snails from escaping. The molluscicidal compositions prepared in each example and comparative example were applied according to the recommended dosage (125g of formulation / acre, equivalent to 0.1875g of formulation / basin based on a 10cm water depth). The number of dead and live snails was counted at 24h, 48h, and 72h after application. No activity and no reaction upon needle prick were considered fatal. Three parallel replicates were set up for each group, and the corrected mortality rate was calculated using the formula.

[0033] II. Poisoning Efficacy Test of Pomacea canaliculata Egg Masses Fresh golden apple snail egg masses were collected, with each mass containing 80-120 eggs and having been produced within 24 hours. The molluscicidal compositions prepared in the examples and comparative examples were diluted with water at a volume ratio of 1:3 and sprayed evenly onto the surface of the egg masses using a handheld sprayer, with a spray volume of 2 mL per egg mass. Water was used as a blank control. Ten egg masses were treated in each group and incubated in an environment of 25-30℃ and 80% relative humidity. The hatching status of the egg masses was observed and recorded daily for 14 consecutive days. The hatching inhibition rate was calculated using the following formula: Hatching inhibition rate (%) = (1 - Hatching rate of treatment group / Hatching rate of control group) × 100%.

[0034] III. Rainwater Erosion Resistance Test The molluscicidal compositions prepared in each example and comparative example were diluted according to the recommended dilution ratio, sprayed onto the surface of a glass slide, and placed under an artificial simulated rainfall device (rainfall intensity 20 mm / h) for 30 min. The residual drug solution on the surface of the glass slide after rinsing was collected, and the residual amount of oleandrin was determined by high performance liquid chromatography. The drug solution loss rate was calculated (loss rate = (initial deposition amount - residual amount after rinsing) / initial deposition amount × 100%).

[0035] IV. Acute Toxicity Tests for Fish Referring to the acute toxicity test method for fish in GB / T 31270.12-2014 "Guidelines for Environmental Safety Evaluation of Chemical Pesticides", zebrafish (Brachydanio rerio) was used as the test organism to determine the 96-hour median lethal concentration (LC50) of the molluscicide compositions prepared in each example and comparative example. 50 ), and calculate the safety factor (safety factor = LC). 50 (Recommended field concentration).

[0036] V. Summary of Results Table 1: Toxicity of different formulations on adult golden apple snails Example 1 92.6±1.8 96.3±1.4 98.2±1.2 Example 2 82.0±2.3 88.5±2.0 92.8±1.9 Example 3 89.2±2.0 94.1±1.6 96.5±1.4 Comparative Example 1 68.5±2.6 74.2±2.4 79.6±2.1 Comparative Example 2 76.8±2.5 82.3±2.2 87.2±1.9 Comparative Example 3 71.2±2.7 77.5±2.4 83.4±2.1 Comparative Example 4 85.3±2.2 90.2±1.9 93.5±1.7 Table 2: Hatching Inhibition Effect and Synergistic Coefficient of Different Formula Treatments on Pomacea canaliculata Egg Masses Example 1 95.8±1.4 Example 2 88.6±2.0 Example 3 93.2±1.6 Comparative Example 1 68.5±2.5 Comparative Example 2 79.8±2.2 Comparative Example 3 74.6±2.4 Table 3: Rainwater erosion resistance and fish toxicity of different formulations Example 1 13.2±1.6 14.2±1.1 9.5 Example 2 16.2±2.0 13.5±1.3 9.0 Example 3 14.5±1.8 13.8±1.2 9.2 Comparative Example 2 43.5±2.6 11.2±1.0 7.5 Comparative Example 3 36.2±2.4 12.5±1.1 8.3 Comparative Example 4 (50% spirodiclofen WP) — 0.38±0.05 0.25 VI. Discussion of Results As shown in Table 1, the low-toxicity and environmentally friendly molluscicidal compositions containing synergistic components prepared in Examples 1-3 of this invention exhibit excellent toxic effects against adult golden apple snails. Example 1 (using the optimal ratio of 25:12.6) achieved corrected mortality rates of 92.6%, 96.3%, and 98.2% at 24h, 48h, and 72h, respectively, significantly better than Examples 2 and 3. Compared to Comparative Example 1, the mortality rates at all time points in Example 1 were significantly higher, indicating that the addition of oleander water extract freeze-dried powder plays an important role in enhancing the molluscicidal effect. Compared to Comparative Example 2, the mortality rates at all time points in Example 1 were significantly higher, indicating that the introduction of chitosan-sodium alginate microcapsules not only imparts sustained-release function but also enhances overall efficacy by protecting the active ingredients from environmental factors. Compared to Comparative Example 3, the efficacy of Example 1 was significantly improved, confirming the key role of polyether-modified trisiloxane as a synergist in promoting drug spread and penetration.

[0037] As shown in Table 2, Example 1 showed a hatching inhibition rate of 95.8% against golden apple snail egg masses, which was significantly better than Comparative Example 1 (68.5%), Comparative Example 2 (79.8%), and Comparative Example 3 (74.6%). This indicates that the combination of metaldehyde, molluscicide, and oleander water extract has a synergistic effect. At the same time, the sustained-release delivery system of chitosan-sodium alginate microcapsules played a positive role in prolonging the effect and protecting the active ingredients.

[0038] As shown in Table 3, the molluscicidal compositions prepared in Examples 1-3 of this invention exhibit excellent resistance to rainwater runoff. Compared with Comparative Example 2, the drug loss rate in Example 1 decreased significantly from 43.5% to 13.2%, a reduction of over 70%, indicating that the chitosan-sodium alginate microcapsules effectively improved the formulation's resistance to rainwater runoff by enhancing the adhesion and sustained release of the active ingredients on the target surface. Compared with Comparative Example 3, the loss rate in Example 1 was further reduced, indicating that the addition of polyether-modified trisiloxane promoted uniform spreading of the drug solution and reduced droplet rolling and loss. Fish toxicity test results showed that the molluscicidal compositions prepared in Examples 1-3 of this invention had a 96h-LC50 effect on zebrafish. 50 The concentration is 13.5-14.2 mg / L, with a safety factor of 9.0-9.5, while the LC50 of traditional 50% molluscicide wettable powder is lower. 50 With a dosage of only 0.38 mg / L and a safety factor of 0.25, this invention reduces the dosage of molluscicide by more than 70% while maintaining high molluscicidal efficacy, thus improving the safety of fish by more than 30 times.

[0039] In summary, the low-toxicity and environmentally friendly molluscicide compositions containing synergistic components prepared in Examples 1-3 of this invention exhibit excellent comprehensive performance. Compared with Comparative Examples 1-4, the examples show the best performance in terms of adult snail toxicity, egg mass hatching inhibition, rainwater washout resistance, and fish toxicity safety. All indicators of Example 1 are superior to those of Examples 2 and 3, indicating that the optimal formulation is a mass ratio of 25:12.6:8 for metaldehyde, molluscicide, and oleander extract, along with a ratio of 12 parts microcapsules and 3.5 parts polyether-modified trisiloxane.

[0040] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the scope defined by the invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A low-toxicity, environmentally friendly molluscicide composition containing synergistic components, characterized in that: Including the following parts by weight of raw materials: Active ingredient group: 10-25 parts of metaldehyde; 5-15 parts of molluscicide; 3-15 parts of freeze-dried oleander water extract powder; Synergist group: 1-6 parts of polyether-modified trisiloxane; Sustained-release carrier group: Chitosan-sodium alginate microcapsules, 5-20 parts; Additives group: 2-5 parts dispersant; 0.5-2 parts wetting agent; 3-6 parts antifreeze; Thickener 0.1-0.5 parts; Defoamer 0.1-0.3 parts; Preservative: 0.1-0.3 parts; Add deionized water to bring the total to 100 parts.

2. The low-toxicity, environmentally friendly molluscicide composition containing synergistic components according to claim 1, characterized in that: The dispersant is sodium lignosulfonate, the wetting agent is sodium dodecyl sulfate, the antifreeze is glycerol, the thickener is xanthan gum, the defoamer is an organosilicon defoamer, and the preservative is sodium benzoate.

3. The low-toxicity, environmentally friendly molluscicide composition containing synergistic components according to claim 1, characterized in that: The mass ratio of metaldehyde to molluscicide is 25:12.

6.

4. The low-toxicity, environmentally friendly molluscicide composition containing synergistic components according to claim 1, characterized in that: The preparation method of the freeze-dried oleander water extract powder specifically includes the following steps: B1. Pulverize dried oleander leaves and pass them through a 60-mesh sieve to obtain oleander powder; B2. Mix the oleander powder obtained in step B1 with deionized water and extract it by stirring in a water bath at 70°C for 1.5 hours to obtain the extract mixture. B3. Filter the extract mixture obtained in step B2, collect the filtrate, and concentrate it to one-fifth of the original volume by rotary evaporation at 50°C to obtain the concentrate. B4. Freeze-dry the concentrated solution obtained in step B3 at -50℃ for 48 hours to obtain oleander water extract freeze-dried powder.

5. The low-toxicity, environmentally friendly molluscicide composition containing synergistic components according to claim 1, characterized in that: In step B2, the mass ratio of oleander powder to deionized water is 1:

10.

6. The low-toxicity, environmentally friendly molluscicide composition containing synergistic components according to claim 1, characterized in that: The preparation method of the chitosan-sodium alginate microcapsules specifically includes the following steps: C1. Chitosan is dissolved in a 0.5 wt% aqueous acetic acid solution to obtain a chitosan acetate solution; lyophilized oleander water extract powder is dissolved in the chitosan acetate solution to obtain an internal aqueous phase; The mass ratio of chitosan, 0.5wt% acetic acid aqueous solution and oleander water extract freeze-dried powder is 1:200:8; C2. Dissolve sodium alginate in deionized water, add Tween-80, and obtain the external aqueous phase; The mass ratio of sodium alginate, deionized water, and Tween-80 is 1:200:1; C3. Slowly drop the inner aqueous phase obtained in step C1 into the outer aqueous phase obtained in step C2, and stir at 1000 r / min for 15 min to obtain an emulsified mixture. C4. Add calcium chloride aqueous solution dropwise to the emulsion mixture obtained in step C3, continue stirring for 30 min, collect the precipitate by centrifugation, wash with deionized water, and freeze dry at -50℃ to obtain chitosan-sodium alginate microcapsules.

7. The low-toxicity, environmentally friendly molluscicide composition containing synergistic components according to claim 1, characterized in that: In step C4, the mass fraction of the calcium chloride aqueous solution is 5%, and the volume ratio of the emulsified mixture to the calcium chloride aqueous solution is 20:

1.

8. The low-toxicity, environmentally friendly molluscicide composition containing synergistic components according to claim 7, characterized in that: The chitosan has a molecular weight of 50 kDa and a degree of deacetylation of 92%; the sodium alginate has a viscosity of 300 mPa·s.

9. A method for preparing a low-toxicity, environmentally friendly molluscicide composition containing synergistic components as described in any one of claims 1-8, characterized in that: Includes the following steps: S1. Weigh out the following ingredients according to the formula: metaldehyde, molluscicide, lyophilized oleander water extract, dispersant, wetting agent, antifreeze agent, and 60-80% of the formula amount of deionized water. Add them to the mixing tank and mix at a stirring speed of 300-500 r / min for 20-30 min to obtain a premixed slurry. S2. The premixed slurry obtained in step S1 is fed to a high-speed shearing machine and sheared at 3000 r / min for 3-5 min to obtain a sheared mixture. S3. Pump the shear mixture obtained in step S2 into a horizontal sand mill, add zirconium oxide grinding media, and perform circulating grinding to obtain qualified grinding material. S4. Transfer the qualified ground material obtained in step S3 to a mixing tank. Add thickener, defoamer and preservative in sequence under slow stirring at 200-400r / min. Stir and mix evenly to obtain the mixed material. S5. Under slow stirring at 200-400 r / min, add polyether-modified trisiloxane dropwise to the mixture obtained in step S4. After the addition is complete, continue stirring for 30 min, then add chitosan-sodium alginate microcapsules, homogenize at 1000 r / min for 2 min, and add the remaining deionized water to bring the total weight to 100 parts to obtain a low-toxicity and environmentally friendly molluscicide composition containing synergistic components.

10. The method for preparing a low-toxicity, environmentally friendly molluscicide composition containing synergistic components according to claim 9, characterized in that: In step S3, the grinding temperature is controlled to be below 35°C until the particle size D90 ≤ 10μm.