Nanometer suspending agent containing thiamethoxam and lufenuron as well as preparation method and application of nanometer suspending agent

Abstract

The invention provides a nano suspending agent containing thiamethoxam and lufenuron as well as a preparation method and application of the nano suspending agent. The nano suspending agent comprises the following components in percentage by mass: 3%-30% of thiamethoxam, 3%-30% of lufenuron, 0.1%-10% of a nano carrier material, 1%-20% of a wetting dispersant, 0.1%-2% of a stabilizer, 0.1%-4% of a thickening agent, 0.02%-1% of a defoaming agent, 0.01%-0.5% of a preservative, 0.1%-8% of an anti-freezing agent, 0.2%-0.8% of a chitosan sodium alginate solution and 30%-70% of a chitosan sodium alginate solution. The invention belongs to the technical field of pesticide preparations, firstly, thiamethoxam and lufenuron are combined for application, a nano carrier material is adopted to load effective components, and a chitosan sodium alginate aqueous solution is added to serve as a film forming material, so that the provided nano suspending agent has a good slow release effect and physical stability while achieving synergistic interaction, and the sustained release effect and the physical stability of the nano suspending agent are greatly improved. And the control effect on adult diaphorina citri and nymphs is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pesticide preparations, and in particular relates to a nano suspension containing thiamethoxam and lufenuron, and a preparation method and application thereof. Background Art

[0002] Huanglongbing (Huanglongbing) is a devastating disease affecting the citrus industry, occurring year-round. It kills young trees, withers or loses fruiting capacity in older trees, and can even wipe out entire orchards. It is one of the most devastating citrus diseases worldwide. Citrus psyllids are the primary natural vector of the Huanglongbing pathogen. They are highly reproductive, with adult psyllids laying eggs on infected young treetops. The hatched nymphs begin to feed on the sap of the young shoots, producing large numbers of infected adults. These infected adults then fly to new plants and spread the disease.

[0003] At present, there is no direct control technology targeting the Huanglongbing pathogen in production practice and promotion and application. The occurrence and spread of citrus Huanglongbing is largely prevented by controlling citrus psyllids. Chemical control is the main way to control citrus psyllids. Thiamethoxam belongs to the second generation of nicotinoid insecticides with high efficiency and low toxicity. It is used for foliar spraying and soil root irrigation. It has stomach poison, contact killing and systemic activity against pests. It can selectively inhibit the nicotinic acid acetylcholinesterase receptors in the insect central nervous system, thereby blocking the normal conduction of the insect central nervous system, causing paralysis and even death of the pests. It is one of the main agents registered in my country for the control of citrus psyllids. However, the long-term and large-scale use of thiamethoxam has led to a high level of resistance in citrus psyllids, thus affecting the efficient control of citrus psyllids. Chinese patent application CN 105766987A discloses an agent for preventing and controlling citrus Huanglongbing disease. By rationally mixing two types of drugs, fungicides and insecticides (each 100 mL of the agent contains 0.5-2g of agricultural streptomycin, 0.5-2g of jinggangmycin, and 1-10mg of thiamethoxam), and applying the drug through the trunk infusion method, citrus Huanglongbing disease can be prevented and controlled to a certain extent. However, due to the difficulty of applying the drug, it is difficult to promote and apply it on a large scale.

[0004] Therefore, it is of great significance to provide a nanosuspension containing thiamethoxam and lufenuron that is easy to apply, as well as a preparation method and application thereof. Summary of the Invention

[0005] To solve the problems existing in the prior art, the present invention combines thiamethoxam and lufenuron in a certain mass ratio, uses a nano-carrier material to load the active ingredients, and adds a low-concentration chitosan sodium alginate aqueous solution as a film-forming material. This allows the provided nanosuspension to achieve synergistic enhancement while also having a good sustained-release effect and physical stability. This not only improves the control effect against citrus psyllid adults and nymphs, but also increases the inhibition rate of their egg hatching, slowing the iterative reproduction rate of citrus psyllids, thereby achieving the goals of reducing pesticide usage and the number of times it is used, reducing resistance, and achieving long-term control of citrus Huanglongbing / citrus psyllids.

[0006] The purpose of the present invention will be further reflected and explained through the following detailed description.

[0007] The invention provides a nano suspension containing thiamethoxam and lufenuron. The nano suspension comprises the following components in percentage by mass: 3%-30% of thiamethoxam, 3%-30% of lufenuron, 0.1%-10% of a nano carrier material, 1%-20% of a wetting and dispersing agent, 0.1%-2% of a stabilizer, 0.1%-4% of a thickener, 0.02%-1% of a defoaming agent, 0.01%-0.5% of a preservative, 0.1%-8% of an antifreeze agent, and 30%-70% of a 0.2%-0.8% chitosan sodium alginate solution.

[0008] By adopting the above technical solution, the present invention is the first to combine thiamethoxam, which has stomach poison, contact and systemic insecticidal effects, and lufenuron, which has a strong egg-killing effect. Nano-carrier materials are used to load the active ingredients, and the drug loading is uniform and has a good sustained-release effect. A low-concentration (0.2%-0.8%) chitosan sodium alginate aqueous solution is added as a film-forming material, so that the provided nano-suspension can achieve synergistic enhancement while also having a good sustained-release effect and physical stability. After spraying, the agent can form a transparent protective film that is resistant to rain erosion and can reduce the emission of crop odor and the damage caused by citrus psyllids sucking sap from tender shoots and leaves. This solves the problems of existing water-based suspensions such as poor film-forming properties and lack of rain erosion resistance. It not only improves the control effect on citrus psyllid adults and nymphs, but also increases the inhibition rate of their egg hatching, slowing the iterative reproduction rate of citrus psyllids, achieving the goals of reducing pesticide usage and the number of applications, extending the effective period of pesticides, reducing resistance, and achieving long-term control of citrus Huanglongbing / citrus psyllids. Controlling the concentration of chitosan sodium alginate solution in the system at 0.2%-0.8% can prevent stratification and solidification during the preparation and storage of the nanosuspension and increase the physical stability of the preparation.

[0009] Preferably, the nanosuspension containing thiamethoxam and lufenuron comprises the following components in percentage by mass: 5% to 30% thiamethoxam, 5% to 30% lufenuron, 1% to 8% nanocarrier material, 4% to 16% wetting and dispersing agent, 0.5% to 1.5% stabilizer, 0.5% to 3% thickener, 0.05% to 0.5% defoaming agent, 0.01% to 0.4% preservative, 0.5% to 6% antifreeze agent, and 35% to 65% 0.2%-0.8% chitosan sodium alginate solution.

[0010] More preferably, the nanosuspension containing thiamethoxam and lufenuron comprises the following components in percentage by mass: 10% to 30% thiamethoxam, 10% to 30% lufenuron, 1% to 4% nanocarrier material, 6% to 12% wetting and dispersing agent, 0.5% to 1.5% stabilizer, 0.5% to 2% thickener, 0.05% to 0.4% defoaming agent, 0.01% to 0.2% preservative, 2% to 4% antifreeze agent, and 45% to 65% 0.2%-0.8% chitosan sodium alginate solution.

[0011] Preferably, the nanocarrier material is selected from one or more of halloysite nanotubes, carbon nanotubes, silica nanotubes, titanium dioxide nanotubes, nanocyclodextrin and nanocalcium carbonate.

[0012] Preferably, the nanocarrier material is halloysite nanotubes. Halloysite nanotubes are widely available, have a hollow tubular structure, and are non-toxic and harmless with active hydroxyl groups on their surface. They have large specific surface area, high porosity, and a large aspect ratio. They have strong adsorption properties and are environmentally friendly and biocompatible.

[0013] Preferably, the wetting and dispersing agent is selected from one or more of lignin sulfonate, sodium dodecylbenzenesulfonate, naphthalenesulfonate, carboxylate, phenethylphenol polyether phosphate, phenol ether phosphate, isomeric alcohol polyoxyethylene ether, high molecular weight block copolymer, alkylphenol polyoxyethylene ether, and dioctyl sodium sulfosuccinate. More preferably, the high molecular weight block copolymer is selected from acrylic acid block copolymer.

[0014] Preferably, the stabilizer is butylated hydroxytoluene (BHT).

[0015] Preferably, the thickener is selected from one or more of magnesium aluminum silicate, xanthan gum, cellulose thickeners (specifically including carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.), polyacrylic acid and methacrylic acid; the defoaming agent is selected from one or more of tributyl phosphate, silicone defoaming agent, corn oil and soybean oil; the preservative is selected from one or more of ammonium benzoate, sodium salicylate, sodium benzoate and benzisothiazolinone; the antifreeze agent is selected from one or more of polyethylene glycol, sorbitol, propylene glycol, glycerol and urea.

[0016] Accordingly, the present invention also provides a method for preparing the nanosuspension containing thiamethoxam and lufenuron, comprising the following steps: weighing thiamethoxam, lufenuron, a nanocarrier material, a wetting and dispersing agent, a stabilizer, a defoaming agent, and an antifreeze agent, adding a portion of 0.2%-0.8% chitosan sodium alginate solution, and then sand-grinding until the particle size is controlled within D 50 ≤200nm or D 90 ≤300nm, then add preservatives, thickeners and the remaining 0.2%-0.8% chitosan sodium alginate solution, and mix them evenly with a homogenizer to obtain a nanosuspension containing thiamethoxam and lufenuron.

[0017] In addition, the present invention also provides the use of the nano suspension containing thiamethoxam and lufenuron in the preparation of a pesticide formulation for preventing and controlling citrus Huanglongbing or citrus psyllid.

[0018] Compared with the prior art, the present invention has the following beneficial effects: the present invention is the first to combine thiamethoxam and lufenuron in a certain mass ratio, and uses nano-carrier materials to load the active ingredients and adds a low-concentration chitosan sodium alginate aqueous solution as a film-forming material, so that the provided nanosuspension achieves synergistic synergy while having a good sustained-release effect and physical stability. It not only improves the control effect on citrus psyllid adults and nymphs, but also increases the inhibition rate of their egg hatching, slowing the iterative reproduction rate of citrus psyllids, achieving the purpose of reducing pesticide usage and the number of times of use, reducing resistance, and achieving long-term control of citrus Huanglongbing / citrus psyllids. It is of great significance for ensuring the sustainable and healthy development of the citrus industry and reducing environmental pollution. In addition, the nanosuspension containing thiamethoxam and lufenuron provided by the present invention is easy to apply, has a relatively simple preparation method, and the prepared nanosuspension has stable performance, avoiding the problem of easy stratification of ordinary suspensions, which is conducive to large-scale promotion and application. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below through specific examples.

[0020] In the present invention, the components involved are all conventional commercial products, or can be obtained by conventional technical means in this field. For example, acrylic block copolymers are purchased from Yinhuang (Shanghai) Industrial Co., Ltd. The 0.2%-0.8% chitosan sodium alginate solution used in the present invention is prepared by adding water to chitosan sodium alginate powder; the preparation method of chitosan sodium alginate powder comprises the following steps: adding chitosan and sodium alginate to a beaker in a mass ratio of 1:1, adding water and stirring thoroughly, adding the stirred mixture to a CaCl2 solution, and performing a cross-linking and curing reaction for 10 to 20 hours. After curing is completed, the excess CaCl2 is poured off, and the cured chitosan sodium alginate is placed in an oven to dry. After drying, it is taken out, ground, and sieved to obtain chitosan sodium alginate powder. In the 0.2% chitosan sodium alginate solution, the mass concentration of the total solute of chitosan and sodium alginate is 0.2%.

[0021] In the present invention, unless otherwise specified, ratios are by mass ratios and percentages are by mass percentages.

[0022] Example 1 40% Thiamethoxam·Lufenuron Nanosuspension

[0023] A 40% thiamethoxam-lufenuron nanosuspension comprises the following components in percentage by mass: 30% thiamethoxam, 10% lufenuron, 3% halloysite nanotubes, 8% alkylphenol polyoxyethylene ether, 2% sodium dodecylbenzenesulfonate, 3% acrylic acid block copolymer, 1% BHT, 1% xanthan gum, 0.2% silicone defoamer, 0.02% benzisothiazolinone, and 4% urea. 0.2% chitosan sodium alginate solution is added to make up the total weight.

[0024] Preparation method: According to the formula, thiamethoxam, lufenuron, halloysite nanotubes, alkylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, acrylic acid block copolymer, BHT, silicone defoamer, and urea were weighed, 0.2% chitosan sodium alginate solution (30% of the amount) was added, and then wet sand milled with a sand mill for 180 minutes at a speed of 2500 r / min. The diluted product particle size was controlled at D 90 ≤300nm, add xanthan gum and benzisothiazolinone after sand grinding, add the remaining 70% of 0.2% chitosan sodium alginate solution to make up, mix evenly with a homogenizer to obtain a 40% thiamethoxam·lufenuron nanosuspension.

[0025] Example 2 30% Thiamethoxam·Lufenuron Nanosuspension

[0026] A 30% thiamethoxam-lufenuron nanosuspension comprises the following components in percentage by weight: 20% thiamethoxam, 10% lufenuron, 2.5% halloysite nanotubes, 8% alkylphenol polyoxyethylene ether, 2% sodium dodecylbenzenesulfonate, 3% acrylic acid block copolymer, 1% BHT, 1% carboxymethyl cellulose, 0.2% silicone defoamer, 0.02% benzisothiazolinone, and 4% propylene glycol. 0.2% chitosan sodium alginate solution is added to make up the total weight.

[0027] Preparation method: same as Example 1.

[0028] Example 3 20% Thiamethoxam·Lufenuron Nanosuspension

[0029] A 20% thiamethoxam-lufenuron nanosuspension comprises the following components in percentage by mass: 10% thiamethoxam, 10% lufenuron, 1.5% halloysite nanotubes, 4% alkylphenol polyoxyethylene ether, 4% isomeric alcohol polyoxyethylene ether, 2% sodium dodecylbenzenesulfonate, 1% BHT, 2% xanthan gum, 0.2% silicone defoamer, 0.02% benzisothiazolinone, 3% glycerol, and 0.5% chitosan sodium alginate solution is added to 100%.

[0030] Preparation method: same as Example 1.

[0031] Comparative Example 1 20% Thiamethoxam·Lufenuron Conventional Suspension Concentrate

[0032] A 20% thiamethoxam / lufenuron conventional suspension concentrate comprises the following components in percentage by weight: 10% thiamethoxam, 10% lufenuron, 4% alkylphenol polyoxyethylene ether, 4% isomeric alcohol polyoxyethylene ether, 2% sodium dodecylbenzenesulfonate, 1% BHT, 2% xanthan gum, 0.2% silicone defoamer, 0.02% benzisothiazolinone, and 3% glycerol. Deionized water is used to make up the total weight. Compared to Example 3, Comparative Example 1 does not contain halloysite nanotubes or the 0.5% chitosan sodium alginate solution; deionized water is used instead.

[0033] Preparation method: According to the formula, thiamethoxam, lufenuron, alkylphenol polyoxyethylene ether, isomeric alcohol polyoxyethylene ether, sodium dodecylbenzene sulfonate, BHT, silicone defoamer, and glycerol were weighed, deionized water (30% of the amount) was added, and then wet sand milled with a sand mill for 180 minutes at a speed of 2500 r / min. The diluted product particle size was controlled at D 90 ≤5μm, after sand grinding, add xanthan gum and benzisothiazolinone, add the remaining 70% of deionized water to make up to 100%, mix evenly with a homogenizer to obtain a 20% thiamethoxam·lufenuron conventional suspension concentrate.

[0034] Comparative Example 2 20% Thiamethoxam·Lufenuron Nanosuspension

[0035] A 20% thiamethoxam-lufenuron nanosuspension comprises the following components in percentage by weight: 10% thiamethoxam, 10% lufenuron, 1.5% halloysite nanotubes, 4% alkylphenol polyoxyethylene ether, 4% isomeric alcohol polyoxyethylene ether, 2% sodium dodecylbenzenesulfonate, 1% BHT, 2% xanthan gum, 0.2% silicone defoamer, 0.02% benzisothiazolinone, and 3% glycerol. Deionized water is used to make up the total weight. Compared to Example 3, Comparative Example 2 does not contain the 0.5% chitosan sodium alginate solution, but uses deionized water instead.

[0036] Preparation method: same as Example 1.

[0037] Test Example 1: Effect of Chitosan Sodium Alginate Solutions of Different Concentrations on Thiamethoxam·Lufenuron Nanosuspension

[0038] A 20% thiamethoxam-lufenuron nanosuspension comprises the following components by weight: 10% thiamethoxam, 10% lufenuron, 1.5% halloysite nanotubes, 4% alkylphenol polyoxyethylene ether, 4% isomeric alcohol polyoxyethylene ether, 2% sodium dodecylbenzene sulfonate, 1% BHT, 2% xanthan gum, 0.2% silicone defoamer, 0.02% benzisothiazolinone, and 3% glycerol. Chitosan sodium alginate solutions of varying concentrations were added to make up the total volume. The storage stability of the 20% thiamethoxam-lufenuron nanosuspensions prepared with chitosan sodium alginate solutions of varying concentrations at room temperature was investigated. The results are shown in Table 1.

[0039] Table 1 Effect of different concentrations of chitosan sodium alginate solution on the stability of 20% thiamethoxam·lufenuron nanosuspension

[0040]

[0041] A 40% thiamethoxam-lufenuron nanosuspension comprises the following components by weight: 30% thiamethoxam, 10% lufenuron, 1.5% halloysite nanotubes, 4% alkylphenol polyoxyethylene ether, 4% isomeric alcohol polyoxyethylene ether, 2% sodium dodecylbenzenesulfonate, 1% BHT, 2% xanthan gum, 0.2% silicone defoamer, 0.02% benzisothiazolinone, and 3% glycerol. Chitosan sodium alginate solutions of varying concentrations were added to make up the total volume. The storage stability of the 40% thiamethoxam-lufenuron nanosuspensions prepared with chitosan sodium alginate solutions of varying concentrations at room temperature was investigated. The results are shown in Table 2.

[0042] Table 2 Effect of different concentrations of chitosan sodium alginate solution on the stability of 40% thiamethoxam·lufenuron nanosuspension

[0043]

[0044] It can be seen from Table 1 and Table 2 that when the chitosan sodium alginate concentration is within the range of 0.2% to 0.8% by mass, adding it to the nanosuspension containing thiamethoxam and lufenuron of the present invention can effectively improve its storage stability.

[0045] Test Example: Investigation of the physical properties of dithiamethoxam·lufenuron nanosuspension

[0046] The nanosuspensions of Examples 1 to 3, and the suspensions of Comparative Examples 1 and 2 were stored at 54°C ± 2°C for 14 days to investigate their stability. The results are shown in Table 3. As can be seen from Table 3, the nanosuspensions prepared by the present invention have a high suspension rate, a small particle size, and good thermal storage stability.

[0047] Table 3 Comparison of storage stability results of different suspension concentrates

[0048] Experimental drugs Suspension rate / % D90 particle size / nm Thermal storage stability Nanosuspension of Example 1 97.56 271 excellent Nanosuspension of Example 2 98.21 268 excellent Nanosuspension of Example 3 98.90 245 excellent Conventional suspending agent of Comparative Example 1 90.42 2400 Difference Nanosuspension of Comparative Example 2 92.31 934 Difference

[0049] In addition, in the laboratory, citrus leaves were sprayed with the nanosuspension of Example 3, the conventional suspension of Comparative Example 1, and the nanosuspension of Comparative Example 2 at the same dosage. Surface tension and other properties were examined, and the results are shown in Table 4. As shown in Table 4, compared with conventional suspensions, the 20% thiamethoxam-lufenuron nanosuspension prepared by the present invention exhibited lower surface tension, a smaller leaf contact angle, and a shorter drying time. Furthermore, a protective film was clearly observed to form on the leaves after spraying. This demonstrates that the nanosuspension provided by the present invention exhibits excellent physical stability after application, ensuring the insecticidal efficacy of the agent while reducing agent waste.

[0050] Table 4 Comparison of leaf film formation and other physical stability results of different suspension concentrates

[0051]

[0052] Test Example: Indoor bioactivity test of trithiamethoxam·lufenuron nanosuspension against citrus psyllids

[0053] (1) Preparation of test insects: Citrus psyllids were collected from citrus trees in the citrus orchard of South China Agricultural University, subcultured in an indoor insectary, and then inoculated onto Murraya osmanthus plants for later use;

[0054] (2) Test agents: Treatment 1: the nanosuspension of Example 1 was diluted 4000 times for standby use; Treatment 2: the nanosuspension of Example 2 was diluted 4000 times for standby use; Treatment 3: the nanosuspension of Example 3 was diluted 4000 times for standby use; Treatment 4: the conventional suspension of Comparative Example 1 was diluted 4000 times for standby use; Treatment 5: the nanosuspension of Comparative Example 2 was diluted 4000 times for standby use; Treatment 6: control agent 1 (30% thiamethoxam, purchased from Shandong Ludedi Biotechnology Co., Ltd.), diluted 4000 times for standby use; Treatment 7: control agent 2 (10% lufenuron, purchased from Hebei Bissell Agricultural Technology Co., Ltd.), diluted 4000 times for standby use; Treatment 8: clear water blank control.

[0055] (3) Test process:

[0056] The indoor bioactivity assay for citrus psyllids involves selecting 20 adult citrus psyllids from each set of petri dishes. Healthy Murraya osmanthus branches are cut and placed in 50ml transparent plastic centrifuge tubes. The bases of the branches are moistened with washed cotton wool and then used for later use. Each group of 20 adult citrus psyllids is immersed in the solution from treatments 1 to 8 for 10 seconds. The tubes are then quickly transferred to seedling-containing centrifuge tubes, sealed with gauze, and incubated under suitable conditions. Three replicates are set for each treatment. Mortality is observed 48 and 72 hours after treatment, and the mortality and adjusted mortality rates are calculated. Death is determined by the absence of a reaction to lightly touching the insect with a brush.

[0057]

[0058] The experimental process for the hatching inhibition rate of citrus psyllid eggs was as follows: healthy branches of Murraya osmanthus were prepared for each group and placed in a 50 ml transparent plastic centrifuge tube. The base of the branches was moisturized with washed cotton. Then 10 female and 10 male citrus psyllids were inoculated and raised in the test tube to lay eggs for 2 days. The branches carrying psyllid eggs were taken out and treated with the drug solution of treatment 1 to treatment 8. The base number of eggs was counted before the drug was used, and the egg hatching status was counted 8 days after the drug was used to calculate the egg hatching inhibition rate.

[0059]

[0060] (4) Test results: As shown in Table 5, after 48 hours and 72 hours of treatment, the 20% thiamethoxam·lufenuron nanosuspension prepared by the present invention can significantly improve the insecticide mortality rate and egg hatching inhibition rate of citrus psyllids compared with conventional suspensions.

[0061] Table 5 Results of indoor bioactivity test of different treatment solutions against citrus psyllids

[0062] Test solution 48h mortality / % 72h adjusted mortality rate / % 8d egg hatching inhibition rate / % Process 1 70.00b 83.64b 89.31b Process 2 66.67c 70.91d 88.58b Process 3 86.67a 96.36a 92.34a Process 4 52.25d 65.72e 79.58c Process 5 70.24b 75.32c 80.16c Process 6 50.00d 61.09f 65.57e Process 7 25.00e 43.64g 71.44d Processing 8 / / /

[0063] Test Example: Field efficacy test of tetrathiamethoxam-lufenuron nanosuspension against citrus psyllids

[0064] (1) Test materials: 6-year-old mandarin orange orchard in Wuming City, Guangxi, with neat trees;

[0065] (2) Experimental process: The field test was carried out on October 15, 2024, when the nymphs and adults of citrus psyllids were mixed in the orchard, and the test was representative; a total of 8 treatments were set up in the test, treatment 1: the nanosuspension of Example 1, diluted 2500 times for standby; treatment 2: the nanosuspension of Example 2, diluted 2500 times for standby; treatment 3: the nanosuspension of Example 3, diluted 2500 times for standby; treatment 4: the conventional suspension of comparative example 1, diluted 2500 times for standby; treatment 5: the nanosuspension of comparative example 2, diluted 2500 times for standby; treatment 6: control agent 1 (30% thiamethoxam, purchased from Shandong Ludedi Biotechnology Co., Ltd.), diluted 2500 times for standby; treatment 7: control agent 2 (10% lufenuron, purchased from Hebei Bissell Agricultural Technology Co., Ltd.), diluted 2500 times for standby; treatment 8: clear water blank control. Each treatment was repeated three times, and the plots were arranged completely randomly, with three mandarin orange trees in each plot. Each replication and the experimental area were separated by one row of mandarin orange trees to avoid the impact of pesticide drift. The weather was clear on the day of pesticide application, which met the conditions for pesticide application. A backpack electric booster sprayer was used to evenly spray the pesticide solutions of treatments 1 to 8 on the leaves of the mandarin orange trees.

[0066] (3) Field investigation and prevention effectiveness calculation

[0067] The base number of citrus psyllids was investigated before treatment, and the number of live citrus psyllids was investigated 3, 7, and 14 days after treatment. One mandarin orange tree was sampled in each plot, and the investigation was conducted from the east, south, west, and north directions. Two tender shoots were randomly inspected at each point, and the number of live citrus psyllids on all eight tender shoots was investigated.

[0068]

[0069] (4) Test results: As shown in Table 6, compared with conventional suspension concentrates, the 20% thiamethoxam·lufenuron nanosuspension prepared in the present invention can significantly improve the field control effect on citrus psyllids, reduce the amount of pesticide used, and prolong the effective control period.

[0070] Table 6 Results of field test on the efficacy of different treatments of pesticides against citrus psyllids

[0071] Test solution 3d prevention and control effect / % 7d control effect / % 14d control effect / % Process 1 74.71c 81.27b 92.54b Process 2 77.34b 82.31b 87.29c Process 3 86.22a 95.75a 97.68a Process 4 62.33d 70.14c 62.37e Process 5 63.42d 75.24d 77.54d Process 6 59.28e 67.25e 61.21e Process 7 35.82f 49.25f 46.67f Processing 8 / / /

[0072] In summary, the thiamethoxam·lufenuron nanosuspension provided by the present invention has good stability, can significantly improve the insecticide mortality rate, and significantly improve the egg hatching inhibition rate, which is beneficial to prolong the effective control period and reduce resistance.

[0073] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A nanosuspension containing thiamethoxam and lufenuron, characterized in that: The invention comprises the following components in percentage by mass: 3% to 30% of thiamethoxam, 3% to 30% of lufenuron, 0.1% to 10% of nano-carrier material, 1% to 20% of wetting and dispersing agent, 0.1% to 2% of stabilizer, 0.1% to 4% of thickener, 0.02% to 1% of defoaming agent, 0.01% to 0.5% of preservative, 0.1% to 8% of antifreeze agent, and 30% to 70% of 0.2% to 0.8% chitosan sodium alginate solution.

2. The nanosuspension containing thiamethoxam and lufenuron according to claim 1, characterized in that: The invention comprises the following components in percentage by mass: 5% to 30% of thiamethoxam, 5% to 30% of lufenuron, 1% to 8% of nano-carrier material, 4% to 16% of wetting and dispersing agent, 0.5% to 1.5% of stabilizer, 0.5% to 3% of thickener, 0.05% to 0.5% of defoaming agent, 0.01% to 0.4% of preservative, 0.5% to 6% of antifreeze agent, and 35% to 65% of 0.2% to 0.8% chitosan sodium alginate solution.

3. The nanosuspension containing thiamethoxam and lufenuron according to claim 2, characterized in that: The invention comprises the following components in percentage by mass: 10% to 30% of thiamethoxam, 10% to 30% of lufenuron, 1% to 4% of nano-carrier material, 6% to 12% of wetting and dispersing agent, 0.5% to 1.5% of stabilizer, 0.5% to 2% of thickener, 0.05% to 0.4% of defoaming agent, 0.01% to 0.2% of preservative, 2% to 4% of antifreeze agent, and 45% to 65% of 0.2% to 0.8% chitosan sodium alginate solution.

4. The nanosuspension containing thiamethoxam and lufenuron according to any one of claims 1 to 3, characterized in that: The nano-carrier material is selected from one or more of halloysite nanotubes, carbon nanotubes, silicon dioxide nanotubes, titanium dioxide nanotubes, nano-cyclodextrin and nano-calcium carbonate.

5. The nanosuspension containing thiamethoxam and lufenuron according to claim 4, characterized in that: The nano-carrier material is halloysite nanotubes.

6. The nanosuspension containing thiamethoxam and lufenuron according to any one of claims 1 to 3, characterized in that: The wetting and dispersing agent is selected from one or more of lignin sulfonate, sodium dodecylbenzene sulfonate, naphthalene sulfonate, carboxylate, phenylethylphenol polyether phosphate, phenol ether phosphate, isomeric alcohol polyoxyethylene ether, high molecular weight block copolymer, alkylphenol polyoxyethylene ether and dioctyl sodium sulfosuccinate.

7. The nanosuspension containing thiamethoxam and lufenuron according to any one of claims 1 to 3, characterized in that: The stabilizer is butylated hydroxytoluene.

8. The nanosuspension containing thiamethoxam and lufenuron according to any one of claims 1 to 3, characterized in that: The thickener is selected from one or more of magnesium aluminum silicate, xanthan gum, cellulose thickener, polypropylene hydrochloride and methacrylic acid; the defoaming agent is selected from one or more of tributyl phosphate, silicone defoaming agent, corn oil and soybean oil; the preservative is selected from one or more of ammonium benzoate, sodium salicylate, sodium benzoate and benzisothiazolinone; and the antifreeze agent is selected from one or more of polyethylene glycol, sorbitol, propylene glycol, glycerol and urea.

9. The method for preparing the nanosuspension containing thiamethoxam and lufenuron according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: weighing thiamethoxam, lufenuron, nano-carrier material, wetting dispersant, stabilizer, defoamer and antifreeze, adding part of 0.2%-0.8% chitosan sodium alginate solution and grinding the mixture until the particle size is controlled within D 50 ≤200nm or D 90 ≤300nm, then add preservatives, thickeners and the remaining 0.2%-0.8% chitosan sodium alginate solution, and mix them evenly with a homogenizer to obtain a nanosuspension containing thiamethoxam and lufenuron.

10. Use of the nanosuspension containing thiamethoxam and lufenuron according to any one of claims 1 to 8 in the preparation of a pesticide formulation for controlling citrus Huanglongbing or citrus psyllid.

Images