Formula and process of S-methoprene-containing mosquito-killing solid block agent

Abstract

The invention belongs to the technical field of insecticides, and discloses an S-methoprene-containing mosquito-killing solid block formula and a process, the S-methoprene-containing mosquito-killing solid block formula comprises the following components by weight: 10% of an S-methoprene active compound, 58% of a carrier, 20% of a binder, 6% of a slow-release matrix, 4% of a lubricant, 0.5% of a synthetic antioxidant, 1% of an ultraviolet screening agent, and 0.5% of a plasticizer. The carrier is diatomite subjected to hydrophobic treatment, and the hydrophobic treatment process of the diatomite comprises the following steps: drying the diatomite at 120 DEG C for 2 hours, performing spraying treatment by using a 5% silane coupling agent, and activating at 80 DEG C for 1 hour. According to the scheme, HPMC E5 is adopted as a slow-release substrate, and a hydrophobic diatomite carrier and an optimization process are combined, so that stable release of S-methoprene is ensured, the lasting period is as long as 90 days or above, the sustained-release preparation is suitable for long-term storage scenes such as marine transportation, chemicals do not need to be supplemented midway, and the maintenance cost is remarkably reduced. As an internationally recognized safe biopesticide, the S-methoprene is free of ecological toxicity and meets the environmental protection requirement for prevention and control of input mosquito-borne diseases in international trade.

Description

Technical Field

[0001] This invention relates to the field of insecticide technology, and more specifically, to a formulation and process for a mosquito-killing solid block containing S-acetamiprid. Background Technology

[0002] Mosquitoes belong to the order Diptera and the family Culicidae, and are one of the most important groups of medically significant insects. They are widely distributed and diverse, with over 3,600 species and subspecies recorded globally across 3 subfamilies, 35 genera, and 3,600 genera. The Culicidae family includes three important genera that not only harass humans through bites and blood-sucking but also transmit various diseases. In China, mosquito-borne infectious diseases mainly include dengue fever, Japanese encephalitis, malaria, and filariasis. Mosquito control is the core means of controlling mosquito-borne infectious diseases, and eliminating mosquito breeding grounds is the most fundamental method. When necessary, highly effective and low-toxicity chemical insecticides should be used as supplementary measures.

[0003] Currently, there are 2015 mosquito control pesticide products registered on the China Pesticide Network, of which only 14 target mosquito larvae. Existing pesticides are mainly chemically synthesized, while nationally approved biological mosquito control agents mainly fall into two categories: 1. Bio-fermentation: such as Bacillus thuringiensis and Bacillus sphaericus. 2. Insect growth regulators: Represented by S-tebufenozide, its structure is similar to insect juvenile hormones. It can interfere with the normal development of mosquito larvae, delay their growth cycle, and prevent them from emerging as adults, thereby achieving the purpose of population control.

[0004] Mosquito larvae primarily breed in stagnant water environments, including natural water bodies (such as ponds), artificial reservoirs, sewers, and specific water-collecting locations (such as discarded tires outdoors). Discarded tires, in particular, are difficult to completely empty once they accumulate water, creating ideal breeding grounds for mosquitoes like Aedes albopictus. Aedes albopictus especially prefers to lay its eggs inside tires, as the rubber material is attractive to it. Every year in my country, a large number of discarded tires or tires carelessly abandoned in the wild accumulate water, and combined with the attractive properties of rubber, this leads to a particularly prominent mosquito breeding problem. In addition, mosquitoes also breed in areas such as large reservoirs, and conventional insecticide spraying only temporarily kills adult mosquitoes, with the effect typically lasting only a few hours, making it difficult to effectively control larval breeding in the long term.

[0005] For the aforementioned waterlogged areas, the application of slow-release pesticides can significantly extend the control period and reduce labor costs. Currently, in tire import and export trade, many countries have required the control of imported mosquitoes, mandating the application of slow-release mosquito control blocks in tires to prevent disease transmission. Therefore, there is an urgent need to develop slow-release block formulations suitable for waterlogged environments such as tires. S-acetamiprid, as an internationally recognized highly safe biological pesticide, has enormous market potential; however, existing formulations are insufficient to meet the demand for long-lasting, sustained-release action. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a formulation and process for a mosquito-repellent solid block containing S-acetamiprid, thereby solving the problem that existing products have short efficacy time and cannot meet the requirements for long-lasting sustained release.

[0007] To address the aforementioned technical problems, the present invention adopts the following technical solution: A mosquito repellent solid block formulation containing S-acetamiprid consists of the following components by weight percentage: S-tebufenozide technical grade 10%, carrier 58%, binder 20%, sustained-release matrix 6%, lubricant 4%, synthetic antioxidant 0.5%, UV protectant 1%, plasticizer 0.5%.

[0008] As a further aspect of the present invention: the carrier is hydrophobically treated diatomaceous earth, and the hydrophobic treatment process of the diatomaceous earth is as follows: After being dried at 120°C for 2 hours, diatomaceous earth was sprayed with 5% silane coupling agent and activated at 80°C for 1 hour.

[0009] As a further aspect of the present invention: the binder is kaolin, and the plasticizer is triethyl citrate.

[0010] As a further aspect of the present invention: the kaolin is sieved through a 200-mesh sieve and then mixed with 0.5% triethyl citrate, and calcined at 500°C for 1 hour.

[0011] As a further aspect of the present invention: the slow-release matrix is ​​HPMC E5, and the lubricant is magnesium stearate.

[0012] As a further aspect of the present invention: the synthetic antioxidant is butylated hydroxytoluene, and the UV stabilizer is titanium dioxide.

[0013] This solution also provides a process for preparing mosquito repellent solid blocks containing S-acetamiprid, comprising the following steps: (1) Preparation of drug solution: S-tebufenozide technical material and butylated hydroxytoluene were dissolved together in anhydrous ethanol, ultrasonically dissolved in a water bath at 40°C for 20 minutes, and 0.2% disodium EDTA was added and stirred until clear to obtain the drug solution; (2) Preparation of HPMC gel: HPMC E5 and 60℃ pure water were mixed at a ratio of 1:10, magnetically stirred for 30 minutes, and then allowed to stand for 2 hours to swell, resulting in a transparent gel; (3) Mixing and granulation: The drug solution prepared in step (1) is loaded onto the hydrophobically treated diatomaceous earth by fluidized bed spraying, and kaolin, magnesium stearate and titanium dioxide are added and dry-mixed for 5 minutes. Then, the HPMC gel prepared in step (2) is added and wet-mixed for 10 minutes. The mixture is granulated by passing it through a 20-mesh sieve and dried with hot air at 50°C until the moisture content is ≤4%. (4) Pressing and molding: Press the granules into cylindrical blocks of Φ30mm×20mm, with a single block weighing 20g; (5) Post-curing treatment: Curing with hot air at 60℃ for 2 hours, then naturally cooling to room temperature and vacuum packaging.

[0014] As a further aspect of the present invention: the mass ratio of the combination of S-tebufenozide technical and butylated hydroxytoluene in step (1) to anhydrous ethanol is 1:4.

[0015] As a further aspect of the present invention: in step (3), the material temperature is controlled at 45-50℃ during wet mixing, and a kneader is used during wet mixing and / or dry mixing, with the kneader blade speed at 40 rpm.

[0016] Compared with the prior art, the advantages of this invention are: I. Long-lasting sustained release and long-lasting control: This solution uses HPMC E5 as the sustained-release matrix, combined with hydrophobic diatomaceous earth carrier and optimized process to ensure stable release of S-acetamiprid, with a duration of more than 90 days. It is suitable for long-term storage scenarios such as sea transport, and there is no need to replenish the agent in the middle, which significantly reduces maintenance costs.

[0017] II. Environmentally friendly and internationally compliant: S-acetamiprid is an internationally recognized safe biological pesticide with no ecotoxicity. It meets the environmental protection requirements for the prevention and control of imported mosquito-borne diseases in international trade and is particularly suitable for mosquito control in water-collecting containers such as waste tires.

[0018] III. High drug loading and stability: The formula contains 10% S-acetamiprid and is treated with antioxidants (butylated hydroxytoluene), UV stabilizers (titanium dioxide) and hydrophobic carriers to effectively delay the degradation of active ingredients and ensure the stability of efficacy under high temperature, high humidity and ultraviolet light environments.

[0019] IV. Process optimization and performance enhancement: Diatomaceous earth is hydrophobically treated with silane coupling agent to improve drug loading uniformity and reduce the influence of moisture; calcined kaolin is compounded with triethyl citrate to enhance adhesion and block mechanical strength; fluidized bed spray loading combined with gel wet mixing process ensures uniform drug dispersion and controllable sustained release rate.

[0020] V. Convenient application and targeted control: The block is designed as a standard cylinder of Φ30mm×20mm, which can be directly put into water-filled places such as tires to slowly release the agent to inhibit the development of mosquito larvae. It is especially suitable for large-scale deployment in scenarios such as container transportation and port yards.

[0021] In summary, this invention combines long-term effectiveness, environmental compatibility, and ease of operation, providing an efficient and sustainable solution to address the risk of mosquito-borne transmission of mosquitoes in cross-border goods. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Example 1 A mosquito repellent solid block formulation containing S-acetamiprid consists of the following components by weight percentage: S-tebufenozide technical grade 10%, carrier 58%, binder 20%, sustained-release matrix 6%, lubricant 4%, synthetic antioxidant 0.5%, UV protectant 1%, plasticizer 0.5%.

[0025] The carrier is hydrophobically treated diatomaceous earth, the binder is kaolin, and the plasticizer is triethyl citrate. The slow-release matrix is ​​HPMC E5, and the lubricant is magnesium stearate. The synthetic antioxidant is butylated hydroxytoluene, and the UV stabilizer is titanium dioxide.

[0026] Example 2 Please see Figure 1 A process for preparing mosquito repellent solid blocks containing S-acetamiprid includes the following steps: I. Raw material pretreatment: Hydrophobic treatment of diatomaceous earth: After drying the diatomaceous earth at 120°C for 2 hours, it is sprayed with 5% silane coupling agent and activated at 80°C for 1 hour.

[0027] Kaolin treatment: Kaolin was sieved through a 200-mesh sieve and then mixed with 0.5% triethyl citrate and calcined at 500℃ for 1 hour.

[0028] II. Preparation of the pesticide solution: Dissolve S-tebufenozide technical material and BHT together in anhydrous ethanol (mass ratio 1:4), and sonicate in a 40°C water bath (300W power) for 20 minutes. Add 0.2% disodium EDTA (based on the total mass of raw materials) and stir until clear to obtain the pesticide solution. It should be noted that the pesticide solution should be prepared and used immediately and should not be stored for more than 4 hours.

[0029] III. Preparation of HPMC gel: HPMC E5 was mixed with 60℃ pure water at a ratio of 1:10, magnetically stirred for 30 minutes, and then allowed to stand for 2 hours to swell, resulting in a transparent gel.

[0030] IV. Mixing and Granulation: The drug solution is sprayed onto the hydrophobically treated diatomaceous earth using a fluidized bed sprayer. Kaolin, magnesium stearate, and titanium dioxide are added and dry-mixed for 5 minutes. Then, HPMC gel is added and wet-mixed for 10 minutes. The mixture is then granulated through a 20-mesh sieve and dried with hot air at 50°C until the moisture content is ≤4%. During wet mixing, the material temperature is controlled at 45-50°C. A kneader is used for both wet and / or dry mixing, with the kneader blades rotating at 40 rpm.

[0031] V. Pressing and molding: Press the granules into cylindrical blocks of Φ30mm×20mm, with a single block weighing 20g; VI. Post-curing treatment: Curing in a 60℃ hot air circulating oven for 2 hours, then naturally cooling to room temperature before vacuum packaging.

[0032] The mechanisms of action of each component in the above formula and process are as follows: S-tebufenozide technical grade: As an internationally recognized safe biological pesticide, it is the core insecticidal ingredient and belongs to the category of insect growth regulators. It controls and prolongs the growth cycle of mosquito larvae, disrupts the normal growth and development pattern, and prevents them from emerging as adults in the larval stage, thus ultimately achieving the effect of controlling mosquitoes.

[0033] Hydrophobic diatomaceous earth: Loads drugs and provides a porous structure. Hydrophobic treatment (silane coupling agent) slows water penetration and controls drug release rate. The diatomaceous earth is dried to remove moisture, and silane spraying enhances the compatibility between the carrier and the drug, activating and improving coupling efficiency.

[0034] Kaolin: Provides mechanical strength and forms a stable skeletal structure after calcination (500℃). Triethyl citrate can reduce the brittleness of kaolin, enhance its binding properties and block mechanical strength, improve its tableting properties, and synergistically optimize porosity with the calcination process.

[0035] HPMC E5: Forms a gel barrier upon contact with water, controlling drug release through diffusion. It disperses in cold water and then swells upon heating to prevent clumping.

[0036] Magnesium stearate: Reduces tableting friction, and its hydrophobic properties help delay water penetration.

[0037] Butylhydroxytoluene: Inhibits the oxidative degradation of S-acetamiprid and synergistically protects the drug with disodium EDTA (which chelates metal ions).

[0038] Titanium dioxide: shields ultraviolet rays, prevents photodegradation, and improves outdoor stability, making it suitable for complex environments such as water-filled containers.

[0039] In summary, ethanol dissolution followed by ultrasonic treatment of S-acetamiprid (40℃) improves dissolution efficiency and avoids high-temperature degradation. The addition of disodium EDTA chelates metal ions, reducing the risk of catalytic oxidation. Fluidized bed spray loading promotes uniform dispersion of the drug solution within the pores of diatomaceous earth, improving drug loading efficiency and preventing excessively high local concentrations. The dual controlled-release mechanism of hydrophobic carrier and gel sustained-release extends the duration of action. Hot air curing (60℃) promotes the recombination of HPMC molecular chains to form a continuous sustained-release film, further delaying release.

[0040] Example 3: Efficacy Verification The following is a test and evaluation conducted in accordance with the "Indoor Efficacy Test and Evaluation of Sanitary Insecticides for Pesticide Registration Part 5: Mosquito Larvae Control Agents" of the People's Republic of China Agricultural Industry Standard NY / T1151.5-2014C. A control effect of <90% is considered ineffective.

[0041] I. Experimental Design: 1. Test reagent: 10% S-acetamiprid block formulation as described in Example 1; 2. Test subject: 3rd instar larvae of Aedes albopictus, 10 larvae per batch / container; 3. Dosage concentration: Place one tablet of the medicine into the container; 4. Simulated Scene: Ten plastic containers were filled with dechlorinated tap water, each with a capacity of 20L, and the water level was marked. Ten third-instar Aedes albopictus larvae were placed in each container. The container opening was covered with a mesh net, and larval feed was scattered into the water. Ten days after application, the number of surviving larvae and pupae was recorded. The mosquitoes were removed from the containers and placed in cups containing dechlorinated tap water. The emergence rate was observed and recorded in rearing cages. Every 10 days, ten third-instar Aedes albopictus larvae were added to each cage, following the same experimental method. The experiment was terminated when the emergence inhibition rate of the insect growth regulator-based mosquito larvae control agent was below 90%. If the water level dropped during the experiment, water was promptly added back to the marked line.

[0042] 5. Observation indicators: Observe the disintegration of the block and continuously release Aedes albopictus mosquitoes into the container to observe the emergence.

[0043] 6. Observation period: 90 days (later extended to 120 days to assess the true validity period) II. Experimental Results: 1. The following are the insecticidal efficacy test data of 10% S-acetamiprid block formulation independently (10 parallel tests, 90-day period):

[0044] 2. Conclusion: 1) Within 90 days: No larvae capable of emerging were found in the subsequent eclosion observation of Aedes albopictus released in the simulated field. The eclosion inhibition rate of all groups was ≥90%, with only a few groups showing a brief decrease in inhibition rate to 90% on day 60 (group: 5), day 80 (group: 3), and day 90 (groups: 6 and 9), but the rate did not remain below the standard.

[0045] 2) Extended observation (120 days): Continued observation after 90 days revealed that under dark and light-protected conditions, the actual effective period of 10% S-tebufenozide blocks was about 120 days, and the disintegration time was about 110 days.

[0046] Example 4: Efficacy verification experiment with an added control group Reference standard: NY / T1151.5-2014 "Indoor Efficacy Tests and Evaluation of Sanitary Insecticides for Pesticide Registration - Part 5: Mosquito Larval Control Agents"; Optimization objective: To verify the specific efficacy of 10% S-acetamiprid block formulation by adding a blank control and an excipient control group, and to eliminate environmental or carrier interference.

[0047] I. Experimental Design 1. Test reagents: Example 1 group: 10% S-acetamiprid block (same formulation as Example 1).

[0048] Control group of excipients: blank block formulation without S-tebufenozide (containing only carrier, binder and other excipients).

[0049] Blank control group: Dechlorinated tap water only (without any chemicals or additives).

[0050] 2. Test subject: 3rd instar larvae of Aedes albopictus, 10 larvae per batch / container.

[0051] 3. Experimental containers and water quality: 30 plastic containers (10 replicates per group), each filled with 20L of dechlorinated tap water (pH 7.0±0.5, hardness 100±10 mg / L CaCO3). Water level was marked and water was added periodically to the initial volume.

[0052] 4. Handling method:

[0053] 5. Observation indicators and periods: Emergence inhibition rate: New larvae were introduced every 10 days, and the number of surviving larvae, pupae, and adults that emerged on the 10th day were recorded.

[0054] Disintegration status: Weigh the residual weight of the block and calculate the disintegration rate (record every 10 days).

[0055] Water quality monitoring: pH, dissolved oxygen, and temperature (25±1℃) are measured every 20 days.

[0056] Observation period: 120 days (covering the time until the disintegration is complete).

[0057] Termination criteria: The experiment was terminated when the feathering inhibition rate of any experimental group was <90% for two consecutive times.

[0058] II. Experimental Results 1. Comparison of feathering inhibition rates (mean values ​​of 10 groups)

[0059] 2. Block disintegration rate (gravimetric method)

[0060] 3. Data Description: 1) Specific efficacy verification: In Example 1, the eclosion inhibition rate was consistently significantly higher than that of the excipient control group, demonstrating that the efficacy came from S-acetamiprid rather than the excipient. Specifically, in Example 1, the eclosion inhibition rate was ≥95% for the first 90 days, only briefly dropping to 90%–95% at a few time points. On day 110, the inhibition rate dropped to 88% (below the 90% standard), indicating that the efficacy began to decline. On day 120, the inhibition rate reached 85%, confirming product failure.

[0061] The excipient control group showed no inhibitory effect in the first 60 days, and the slight inhibition in the later period (5% to 7%) may be due to physical coverage, but there was no significant difference from the blank control group. The emergence rate of the blank control group was >90%, confirming that the experimental environment did not unexpectedly inhibit mosquito growth.

[0062] 2) Relationship between disintegration and drug efficacy: In Example 1, the disintegration rate of the block formulation reached 100% on day 110, and the efficacy was maintained until day 120 (inhibition rate 85%), indicating that the release of the active ingredient slowed down in the later stages.

[0063] 3) Interference elimination: The larvae in the control group with excipients developed normally, eliminating the possibility of interference from physical covering of the block agent or toxicity of the excipients.

[0064] Data analysis based on Examples 1-4: 1. Validity: 1) The synergistic effect of the hydrophobic diatomaceous earth carrier and HPMC slow-release matrix in the formulation ensures the stable release of S-acetamiprid.

[0065] 2) Antioxidants (BHT) and UV stabilizers (TiO2) effectively protect the stability of the active ingredients.

[0066] 2. Differences: In some groups, the inhibition rate fluctuated (90%) between days 60 and 90, which may be related to differences in larval density, but there was no statistical significance overall.

[0067] 3. Process Evaluation: 1) The hydrophobic diatomaceous earth treatment and kaolin calcination process enhanced the adsorption and stability of the carrier.

[0068] 2) The wet mixing temperature (45-50℃) and the low-speed mixing of the kneader (40rpm) prevented the degradation of heat-sensitive components.

[0069] In summary: The 10% S-acetamiprid solid block formulation provided by this invention, under simulated field conditions: 1. Sustained effectiveness: The feathering inhibition rate meets industry standards (≥90%) within 90 days, and the actual effective period can reach 120 days.

[0070] 2. Sustained-release performance: The disintegration period is consistent with the efficacy period, which verifies the rationality of the sustained-release design of the formulation.

[0071] 3. Stability: The antioxidant and UV protection system effectively ensures the long-term efficacy of the active ingredients.

[0072] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A formulation for a mosquito-repellent solid block containing S-acetamiprid, characterized in that: It consists of the following components by weight percentage: S-tebufenozide technical grade 10%, carrier 58%, binder 20%, sustained-release matrix 6%, lubricant 4%, synthetic antioxidant 0.5%, UV protectant 1%, plasticizer 0.5%.

2. The mosquito repellent solid block formulation containing S-acetamiprid according to claim 1, characterized in that: The carrier is hydrophobically treated diatomaceous earth, and the hydrophobic treatment process for the diatomaceous earth is as follows: After being dried at 120°C for 2 hours, diatomaceous earth was sprayed with 5% silane coupling agent and activated at 80°C for 1 hour.

3. The mosquito repellent solid block formulation containing S-acetamiprid according to claim 1, characterized in that: The binder is kaolin, and the plasticizer is triethyl citrate.

4. The mosquito repellent solid block formulation containing S-acetamiprid according to claim 3, characterized in that: The kaolin was sieved through a 200-mesh sieve and then mixed with 0.5% triethyl citrate, and calcined at 500°C for 1 hour.

5. The mosquito repellent solid block formulation containing S-acetamiprid according to claim 1, characterized in that: The slow-release matrix is ​​HPMC E5, and the lubricant is magnesium stearate.

6. The mosquito repellent solid block formulation containing S-acetamiprid according to claim 1, characterized in that: The synthetic antioxidant is butylated hydroxytoluene, and the UV stabilizer is titanium dioxide.

7. A process for preparing the mosquito-repellent solid block containing S-acetamiprid as described in any one of claims 1-6, characterized in that: Includes the following steps: (1) Preparation of drug solution: S-tebufenozide technical material and butylated hydroxytoluene were dissolved together in anhydrous ethanol, ultrasonically dissolved in a water bath at 40°C for 20 minutes, and 0.2% disodium EDTA was added and stirred until clear to obtain the drug solution; (2) Preparation of HPMC gel: HPMC E5 and 60℃ pure water were mixed at a ratio of 1:10, magnetically stirred for 30 minutes, and then allowed to stand for 2 hours to swell, resulting in a transparent gel; (3) Mixing and granulation: The drug solution prepared in step (1) is loaded onto the hydrophobically treated diatomaceous earth by fluidized bed spraying, and kaolin, magnesium stearate and titanium dioxide are added and dry-mixed for 5 minutes. Then, the HPMC gel prepared in step (2) is added and wet-mixed for 10 minutes. The mixture is granulated by passing it through a 20-mesh sieve and dried with hot air at 50°C until the moisture content is ≤4%. (4) Pressing and molding: Press the granules into cylindrical blocks of Φ30mm×20mm, with a single block weighing 20g; (5) Post-curing treatment: Curing with hot air at 60℃ for 2 hours, then naturally cooling to room temperature and vacuum packaging.

8. The process for the mosquito-repellent solid block containing S-tebufenozide according to claim 7, characterized in that: In step (1), the mass ratio of the combination of S-tebufenozide technical and butylated hydroxytoluene to anhydrous ethanol is 1:

4.

9. The process for the mosquito-repellent solid block containing S-acetamiprid according to claim 7, characterized in that: In step (3), the material temperature is controlled at 45-50℃ during wet mixing. A kneader is used for wet mixing and / or dry mixing, and the kneader blade speed is 40 rpm.

Images