Thiamethoxam ultra-low volume oil preparation, its preparation method and application for controlling aphids of rape

Abstract

The application provides a thiamethoxam ultra-low volume oil agent, a preparation method thereof and application for controlling aphids of rape, and relates to the technical field of pesticides. The thiamethoxam ultra-low volume oil agent is prepared by taking a cocoyl ester compound as a solvent and fatty acid methyl ester and chlorinated paraffin as fillers, and is specially used for agricultural unmanned aerial vehicles. The oil agent has low surface tension, small contact angle and fast wetting speed, effectively copes with the hydrophobic structure of the surface of rape leaves, and improves the utilization efficiency of the pesticide. After being sprayed by the unmanned aerial vehicle, the thiamethoxam ultra-low volume oil agent can be durably adhered to the leaves or pods, and aphids can be effectively controlled.

Description

Technical Field

[0001] This invention provides a thiamethoxam ultra-low volume oil formulation, its preparation method, and its application in controlling rapeseed aphids, belonging to the field of pesticide technology. Background Technology

[0002] Rapeseed is an important oilseed crop in my country, and aphids are its most significant pests. Aphids cause serious damage to rapeseed by sucking sap from the phloem, secreting honeydew, and spreading plant pathogens and viruses. Aphids can also transmit turnip yellow mosaic virus and sclerotinia rot by feeding on the phloem sap of infected plants. Furthermore, the peak period of aphid infestation coincides with the flowering and pod-setting stage of rapeseed, when the plants are tall and dense, making manual pesticide application not only difficult but also increasing the risk of pesticide poisoning for farmers.

[0003] Agricultural drones are ideal tools for controlling aphids in rapeseed fields due to their high operational efficiency, strong emergency control capabilities, and lack of limitations imposed by crop growth and terrain. However, existing conventional pesticide formulations are not suitable for direct drone spraying. They require high dilution with water and are prone to nozzle wear and explosion risks. More importantly, the superhydrophobic waxy layer covering rapeseed leaves makes the high-concentration pesticide droplets more susceptible to bounce and splashing during drone spraying, significantly reducing pesticide deposition efficiency. Furthermore, droplets falling from high altitudes are more prone to drift and evaporation, leading to pesticide loss.

[0004] In response to the current problems of difficulty in applying pesticides during the pod-setting stage of rapeseed, superhydrophobic rapeseed leaves, and lack of specialized formulations for plant protection drones, there is an urgent need to develop a new type of pesticide product. Summary of the Invention

[0005] Based on this, the present invention provides a thiamethoxam ultra-low volume oil formulation, its preparation method, and its application in controlling rapeseed aphids. The thiamethoxam ultra-low volume liquid formulation prepared by the present invention, when applied in conjunction with agricultural drones, effectively solves many problems in rapeseed production, such as rural labor shortages, hydrophobic rapeseed leaves, difficulties in manual application during the pod-setting stage, and high risks of pesticide poisoning for farmers. It has great potential for widespread application in water-scarce mountainous areas.

[0006] The present invention is specifically implemented using the following technical solutions: A method for preparing a thiamethoxam ultra-low volume oil formulation includes the following steps: Thiamethoxam technical grade was added to the coconut oil-based esterified complex and stirred until the thiamethoxam was completely dissolved. Then fatty acid methyl ester and chlorinated paraffin were added and stirring continued until the mixture changed from a cloudy milky white to a transparent pale yellow. Stirring was then stopped to obtain thiamethoxam ultra-low volume oil.

[0007] Preferably, the mass ratio of the thiamethoxam technical material to the coconut oil-based esterified complex is 1:3 to 10, and more preferably, the mass ratio is 1:5.

[0008] Preferably, the coconut oil-based esterified complex is produced by Shandong Binnong Technology Co., Ltd. (production batch number: 2025010602, specification: 100g), and is specifically composed of the following components: coconut oil fatty acids, glycerol, sorbitol, ethoxylated fatty alcohol, alkyl glycoside, maleic anhydride monoesterified coconut oil amine, isopropanol, and water.

[0009] Preferably, the mass ratio of the thiamethoxam technical material to the fatty acid methyl ester is 1:30~65.

[0010] Preferably, the mass ratio of the thiamethoxam technical material to the chlorinated paraffin is 1:30~70.

[0011] The present invention also provides a thiamethoxam ultra-low volume oil formulation, which is prepared using thiamethoxam technical, coconut oil-based esterified complex, fatty acid methyl ester and chlorinated paraffin as raw materials.

[0012] The thiamethoxam ultra-low volume oil formulation described in this invention is applied by drone for the control of rapeseed aphids.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a coconut oil-based esterified complex as a solvent and fatty acid methyl esters and chlorinated paraffin as fillers to prepare a thiamethoxam ultra-low volume oil formulation specifically for agricultural drones. This oil exhibits low surface tension, a small contact angle, and rapid wetting, effectively addressing the hydrophobic structure of rapeseed leaves and improving pesticide utilization efficiency. After drone spraying, the thiamethoxam ultra-low volume oil formulation can persistently adhere to leaves or pods, effectively controlling aphids. 21 days after spraying, the field control efficacy remained above 94.60%. The degradation kinetics of thiamethoxam in rapeseed conformed to first-order kinetics, with a degradation half-life of 4.28–5.47 days. At final harvest, the thiamethoxam residue was below 0.0067 mg·kg⁻¹. -1 It meets national food safety standards. This invention, thiamethoxam ultra-low volume oil formulation, when used in conjunction with agricultural drones, effectively solves the problems of labor shortages in rural areas, the hydrophobicity of rapeseed surfaces, the inconvenience of manual spraying during the pod-setting stage, and the risk of pesticide poisoning associated with manual spraying. It has great potential for widespread application in water-scarce mountainous areas. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the preferred embodiments of this invention will be described in further detail below with reference to the examples. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0015] Example 1 Weigh 20.0 g of thiamethoxam technical grade and add it to 100.0 g of coconut oil-based esterified complex. Shear the mixture with a high-speed shearing machine until the thiamethoxam is completely dissolved. Then add 1300.0 g of fatty acid methyl ester and 600.0 g of chlorinated paraffin and continue shearing. Stop stirring when the mixture changes from turbid milky white to transparent light yellow. Store in the dark for later use to obtain thiamethoxam ultra-low volume oil.

[0016] Example 2 Weigh 20.0 g of thiamethoxam technical grade and add it to 100.0 g of coconut oil-based esterified complex. Shear the mixture with a high-speed shearing machine until the thiamethoxam is completely dissolved. Then add 1000.0 g of fatty acid methyl ester and 900.0 g of chlorinated paraffin and continue shearing. Stop stirring when the mixture changes from turbid milky white to transparent light yellow. Store in the dark for later use to obtain thiamethoxam ultra-low volume oil.

[0017] Example 3 Weigh 20.0 g of thiamethoxam technical grade and add it to 100.0 g of coconut oil-based esterified complex. Shear the mixture with a high-speed shearing machine until the thiamethoxam is completely dissolved. Then add 700.0 g of fatty acid methyl ester and 1200.0 g of chlorinated paraffin and continue shearing. Stop stirring when the mixture changes from turbid milky white to transparent light yellow. Store in the dark for later use to obtain thiamethoxam ultra-low volume oil.

[0018] Example 4 Weigh 20.0 g of thiamethoxam technical grade and add it to 100.0 g of coconut oil-based esterified complex. Shear the mixture with a high-speed shearing machine until the thiamethoxam is completely dissolved. Then add 500.0 g of fatty acid methyl ester and 1400.0 g of chlorinated paraffin and continue shearing. Stop stirring when the mixture changes from turbid milky white to transparent light yellow. Store in the dark for later use to obtain thiamethoxam ultra-low volume oil.

[0019] The performance of the thiamethoxam ultra-low volume liquid preparations prepared in Examples 1-4 was characterized as follows: 1. Density and Viscosity At room temperature, the density of the thiamethoxam ultra-low volume liquid was determined using the isovolumetric method. A specific volume of the thiamethoxam ultra-low volume liquid was accurately measured into a weighing dish using a pipette, and its mass was measured. This process was repeated five times, and the sample density was calculated based on the mass and volume, with the average value taken. The sample viscosity was measured using a rotational viscometer (Brookfield DV2T). The density and viscosity of the thiamethoxam ultra-low volume liquid prepared in the above examples are shown in Table 1.

[0020] Table 1

[0021] 2. Volatility The evaporation rate of ultra-low volume liquid was determined by the filter paper suspension method. First, the mass m1 of the filter paper (diameter 12.5 mm) was weighed, and then 1 mL of the sample to be tested was dropped onto the filter paper. After the liquid was evenly spread, the total mass m2 was recorded. Then, the filter paper was suspended in an oven at 30±1 ℃ for 20 min. Finally, the mass m3 was weighed, and the evaporation rate was calculated according to formula (1).

[0022] (1) The volatilization rates of the thiamethoxam ultra-low volume liquid preparations prepared in Examples 1-4 were tested and are shown in Table 2.

[0023] Table 2

[0024] 3. Stability of thiamethoxam ultra-low volume liquid under heat and cold storage Accurately measure 20 mL of ultra-low volume liquid and add it to a 50 mL graduated cylinder with a stopper. Seal the opening with sealing film and place the sample in a refrigerator at 0±1 ℃. Observe the physical properties (whether there is solid precipitation, layering, etc.) every 15 minutes. After 1 hour, continue to store the graduated cylinder for 7 days. Then, remove it and let it stand at room temperature (≤25 ℃) for 3 hours to observe the low-temperature stability of the ultra-low volume liquid. Using the same method, place the graduated cylinder in an oven pre-set to 54±2 ℃. After 14 days, remove the sample and determine the decomposition rate. A decomposition rate ≤5% is considered acceptable.

[0025] Table 3

[0026] 4. Determination of active ingredient content Accurately weigh 0.1 g of sample (accurate to 0.0001 g) into a 50 mL volumetric flask, add an appropriate amount of methanol, sonicate for 30 min to dissolve, and after the sample cools to room temperature, make up to volume with methanol. Use high performance liquid chromatography (HPLC) to determine the content of active ingredients in the thiamethoxam ultra-low volume liquid.

[0027] Table 4

[0028] 5. Maximum retention Take fresh rapeseed leaves and cut them into 2×2 cm pieces. 2 Weigh the leaf using an analytical balance, then hold it with tweezers and place it vertically into the preparation for 20 seconds. Quickly pull the leaf out of the liquid and hang it vertically until no more droplets fall. Weigh the leaf again, then repeat this process 5 times. Calculate the maximum retention amount Rm (mg / cm³) of the sample on the rapeseed leaf according to formula (2). 2 ).

[0029] Rm=(W1 - W0) / 4 (2) Table 5

[0030] 6. Surface tension and contact angle The surface tension of each sample was measured using an SCA20 v50 contact angle meter with an SNP241 / 180 needle and the pendant drop method. Each sample was measured five times, and the average value was taken. An appropriate amount of Allura Red AC dye was added to an ultra-low volume liquid, and 100 μL of the liquid was vertically deposited onto the surface of rapeseed leaves using a pipette. The spreading process was recorded video. For static contact angle measurement, an SNS-type injection needle was used with a droplet volume of 2.0 μL. After spotting, the sample stage knob was rotated to gently transfer the droplet to the rapeseed leaf surface. A complete image of the droplet spreading was captured, and the contact angle was measured. Each sample was tested five times, and the average value was taken.

[0031] Table 6

[0032] 7. Test of rainwater erosion resistance of thiamethoxam ultra-low volume liquid formulation Cut the rapeseed leaves into 2×2 cm pieces. 2 To determine the sample size, fix the upper surface of the leaf upwards in the center of a glass slide. Add 0.1 g (accurate to 0.0001 g) of sample to the center of the rapeseed leaf. After adding the sample, dry it in an oven at 25 ℃ for 2 hours. Then, rinse the leaf with 30% methanol-water using an acid burette. The tilt angle of the burette should be approximately 45°. Rinse each leaf 5 times, with a rinsing volume of 1.0 mL each time. The water droplet falling speed should be 3 d / s, and the vertical distance between the burette outlet and the leaf should be 2 cm. Repeat the process 3 times. The content is determined by HPLC.

[0033] Table 7

[0034] Field trials were conducted using the thiamethoxam ultra-low volume oil formulation prepared in Example 1, as detailed below: The rapeseed experimental field was located in Guangshun Farm, Changshun County, Guizhou Province. The rapeseed variety used was Youyan 2020, provided by the Guizhou Provincial Rapeseed Research Institute. The target pest was the rapeseed aphid (Brevicoryne brassicae). The experimental field suffered from severe aphid infestations year-round. All experimental plots had identical cultivation conditions (soil type, fertilization, growth stage), management methods, and growth status. The experiment was conducted in April and May. A randomized block design was used in the field trial, with four treatment groups and one control group. Each plot was 150 m². 2The experiment was repeated four times. The treatment groups were: experimental group (1% thiamethoxam ultra-low volume oil formulation from Example 1), with application rates of 15 g ai / ha, 30 g ai / ha, and 45 g ai / ha; control group (25% thiamethoxam water-dispersible granules purchased from Tianjin Huayu Pesticide Co., Ltd.), with an application rate of 30 g ai / ha; and blank control group sprayed with water. The entire experiment utilized drone spraying technology. During drone spraying, the field temperature was 30℃, relative humidity was 70%, and wind speed was 2.8 m / s.

[0035] Single application of 15, 30, and 45 g ai / hm 2 After spraying 1% thiamethoxam at ultra-low concentrations, the residue of thiamethoxam in rapeseed pods gradually decreased over time. 45 g ai / hm 2 Two hours after application, the residue of thiamethoxam in rapeseed pods reached 11.20 mg·kg⁻¹. -1 Twenty-one days after application, the average residual amounts at the three dosages ranged from 0.1341 to 0.6810 mg / kg. -1 The value indicates a relatively persistent effect. The degradation half-life of thiamethoxam in rapeseed pods was 4.35–5.44 days, consistent with previous findings in spinach, indicating rapid degradation in chlorophyll-rich plants. At final harvest, thiamethoxam residues were below 0.0067 mg / kg. -1 It is below the national food safety standards.

[0036] Table 8

[0037] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a thiamethoxam ultra-low volume oil formulation, characterized in that, Includes the following steps: Thiamethoxam technical grade was added to the coconut oil-based esterified complex and stirred until the thiamethoxam was completely dissolved. Then fatty acid methyl ester and chlorinated paraffin were added and stirring continued until the mixture changed from a cloudy milky white to a transparent pale yellow. Stirring was then stopped to obtain thiamethoxam ultra-low volume oil.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the thiamethoxam technical material to the coconut oil-based esterified complex is 1:3~10.

3. The preparation method according to claim 1, characterized in that, The coconut oil-based esterified complex is prepared from coconut oil fatty acids, glycerol, sorbitol, ethoxylated fatty alcohols, alkyl glycosides, maleic anhydride monoesterified coconut oil amine, isopropanol, and water.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the thiamethoxam technical material to the fatty acid methyl ester is 1:30~65.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the thiamethoxam technical material to the chlorinated paraffin is 1:30~70.

6. A thiamethoxam ultra-low volume oil formulation, characterized in that, It is prepared using any one of the methods described in claims 1 to 5.

7. The application of the thiamethoxam ultra-low volume oil formulation as described in claim 6 in the control of rapeseed aphids.

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