A pesticide microcapsule and its application

Abstract

The invention discloses a pesticide microcapsule and its application, belonging to the technical field of pesticides. The pesticide microcapsule is prepared by the following method: adding the pesticide active ingredient to ethyl acetate, and then adding polylactic acid, stirring evenly, and obtaining an organic phase; the pesticide active ingredient is composed of a bifenthrin-thiamethoxam complex and piperine in a mass ratio of 1: (1-3); polyvinyl alcohol is dissolved in water to obtain an aqueous phase; under ice-water bath conditions, the organic phase is added dropwise to the aqueous phase, and stirred at the same time to form an emulsion; the emulsion is stirred and evaporated, centrifuged, washed, and dried to obtain a pesticide microcapsule. The present invention prepares pesticide microcapsules by compounding bifenthrin, clothianidin and piperine, effectively avoiding the drug resistance of pests caused by the action of a single agent, and piperine not only directly produces a toxic effect on pests, but also can enhance the insecticidal effect of bifenthrin and clothianidin, and achieves a synergistic effect of 1+1>2.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticides, and in particular to a pesticide microcapsule and application thereof. Background Art

[0002] The two-spotted spider mite (Tetranychus urticae) is an important economic crop pest widely distributed around the world. It mainly attacks vegetables, fruit trees and ornamental plants. It sucks the sap of leaves, causing yellowing of leaves, premature shedding, plant weakness and even death, which seriously affects crop yields. Current control methods include chemical control, biological control and agricultural control, among which chemical control is still the mainstream because of its rapid effect and simple operation. However, due to its rapid reproduction and short life cycle, the two-spotted spider mite quickly develops resistance to organophosphates, pyrethroids and avermectins, and its resistance mechanisms are diverse, including metabolic detoxification (such as increasing P450 enzyme activity), target mutation and behavioral resistance, which makes the control effect of a single agent continue to decline and the control difficulty increases. At the same time, aphids (such as chrysanthemum aphids) also face similar resistance problems. Their resistance to chemical pesticides continues to increase, especially to neonicotinoids and pyrethroids, which seriously affects the sustainability of agricultural production. The mechanisms of aphid resistance development include gene mutation and enhanced metabolic capacity, which greatly reduce the effectiveness of conventional chemical control measures. Therefore, the development of new control strategies, especially through pesticide combination solutions to deal with resistance, has become an urgent issue to be addressed.

[0003] Bifenthrin interferes with the sodium ion channels of pests, causing their nervous system to malfunction, and has a good contact killing effect. However, due to the long-term use of pyrethroids, many pests have gradually developed resistance to bifenthrin, which has reduced its effectiveness when used alone. As a neonicotinoid agent, clothianidin mainly acts on the acetylcholine receptors of pests, interferes with nerve conduction, and has an inhibitory effect on the feeding and reproduction of pests. Clothianidin has certain systemic and systemic conduction properties, can enter the internal circulation of plants, and has a good control effect on hidden pests. By compounding bifenthrin with clothianidin, multi-target attack can be achieved, delaying the development of pest resistance to a single agent, thereby improving the reliability of control. In addition, the combination of the rapid effect of bifenthrin and the persistence of clothianidin can provide longer protection. However, although compounding can delay the development of resistance, after long-term use, pest resistance to these two agents may continue to accumulate. Piperine is an amide alkaloid component extracted from the fruit of the pepper plant of the Piperaceae family. Studies have shown that piperine and its derivatives have insecticidal activity against a variety of agricultural pests. They inhibit the metabolic and detoxification enzymes in the pests, especially the cytochrome P450 enzyme, to improve the insecticidal effect of other pesticides. They can also delay the development of drug resistance by blocking the metabolic and detoxification pathways of pests, especially in resistant pest groups. However, piperine is easily degraded in sunlight, which may lead to a weakening of the efficacy and affect the long-lasting effect of compound products.

[0004] Microcapsule technology uses materials with slow-release function to wrap pesticides to control the release rate of pesticides and prolong their release time. This not only reduces the acute toxicity of pesticides, but also makes the efficacy last longer and has better control effects. Preparing bifenthrin, clothianidin and piperine into pesticide microcapsules can give full play to the advantages of these three ingredients. At present, there are no reports on the use of bifenthrin, clothianidin and piperine in microcapsules for pest control. Summary of the invention

[0005] In view of the above-mentioned prior art, the object of the present invention is to provide a pesticide microcapsule and application thereof.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a pesticide microcapsule prepared by the following method:

[0008] (1) adding an active ingredient of the pesticide to ethyl acetate, and then adding polylactic acid, stirring evenly to obtain an organic phase; the active ingredient of the pesticide is composed of a bifenthrin-thiamethoxam complex and piperine in a mass ratio of 1:(1-3);

[0009] (2) dissolving polyvinyl alcohol in water to obtain an aqueous phase;

[0010] (3) In an ice-water bath, the organic phase is added dropwise to the aqueous phase while stirring to form an emulsion;

[0011] (4) The emulsion is stirred and evaporated to remove ethyl acetate, and the precipitate is collected by centrifugation, washed, and freeze-dried to obtain pesticide microcapsules.

[0012] Preferably, in step (1), the bifenthrin-clothianidin complex consists of bifenthrin and clothianidin in a mass ratio of 1:1.

[0013] Preferably, in step (1), the mass ratio of the bifenthrin-thiamethoxam complex to piperine is 1:2.

[0014] Preferably, in step (1), the ratio of the added amount of the pesticide active ingredient to that of ethyl acetate is 1 g: (10-20) mL.

[0015] Preferably, in step (1), the mass ratio of the pesticide active ingredient to the polylactic acid is 1:(1.5-2.5).

[0016] Preferably, in step (2), the mass concentration of polyvinyl alcohol in the aqueous phase is 0.5%-2%.

[0017] Preferably, in step (3), the volume ratio of the organic phase to the aqueous phase is 1:(4-10).

[0018] Preferably, in step (3), the stirring speed is 10000-15000 rpm, and the stirring time is 10-30 min.

[0019] Preferably, in step (4), the temperature of stirring and evaporating is 25-40° C. and the time is 1-3 h.

[0020] The second aspect of the present invention provides the use of the above pesticide microcapsules in controlling two-spotted spider mites or chrysanthemum aphids.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention prepares pesticide microcapsules by compounding bifenthrin, clothianidin and piperine. Bifenthrin, as a pyrethroid insecticide, mainly interferes with the sodium ion channel of pests, causing nervous system disorders, and has a strong contact killing effect on pests; clothianidin belongs to the neonicotinoid insecticide, acts on the acetylcholine receptors of pests, blocks nerve conduction, and inhibits the feeding and reproduction behavior of pests; piperine, as a natural synergist, can inhibit the metabolic detoxification enzyme system (such as cytochrome P450 enzyme) in the pest body, improve the insecticidal effect of other pesticides, and delay the generation of drug resistance; through multi-target and multi-mechanism compounding, the drug resistance of pests caused by the action of a single agent is effectively avoided, and the effective use period of the pesticide is extended. The addition of piperine not only directly produces a toxic effect on the pests, but also inhibits the activity of the detoxification enzyme of the pests, enhances the insecticidal effect of bifenthrin and clothianidin, and achieves a synergistic effect of 1+1>2.

[0023] 2. Microcapsule coating technology is adopted, and polylactic acid (PLA) is used as the wall material, which is biodegradable. The active ingredients of pesticides are encapsulated in polylactic acid (PLA) microcapsules, which protect the active ingredients of pesticides and prevent them from being degraded under environmental factors such as light and temperature, especially providing effective protection for the photosensitivity of piperine; microcapsules can control the release rate of pesticides, achieve a sustained-release effect, prolong the duration of drug efficacy, and reduce the number of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 : A photograph of the pesticide microcapsules prepared in Example 1 magnified 500 times under an electron microscope;

[0025] Figure 2 : In Test Example 2, a photograph of chrysanthemum aphids killed in a field test of controlling chrysanthemum aphids using the pesticide microcapsules prepared in Example 1 falling on the mulch film;

[0026] Figure 3 : In Test Example 2, photos of chrysanthemum aphids killed on chrysanthemum leaves in a field test of controlling chrysanthemum aphids using the pesticide microcapsules prepared in Example 1. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0028] As described in the background art, the problem of pesticide resistance of agricultural pests is becoming increasingly serious, and the effectiveness of traditional single pesticide control strategies is gradually declining, posing a huge challenge to agricultural production.

[0029] Based on this, the present invention forms a pesticide preparation with multiple action mechanisms by compounding bifenthrin, clothianidin and piperine in a specific ratio and coating them with microcapsule technology. The present invention aims to comprehensively utilize the advantages of these three active ingredients to achieve efficient prevention and control of two-spotted spider mites and chrysanthemum aphids. Bifenthrin has a quick effect and can quickly interfere with the nervous system of two-spotted spider mites, producing a rapid contact killing effect; clothianidin has a persistent effect and systemicity, and provides a long-term protective effect by inhibiting the acetylcholine receptors of pests; piperine, as a natural synergist, can inhibit the metabolic detoxification enzyme system in the pest body, enhance the insecticidal effect of other pesticides, and delay the generation of drug resistance. At the same time, the compounded pesticide is coated with microcapsule technology, and the microcapsule has a large specific surface area and excellent permeability, which can improve the adhesion and absorption efficiency of the pesticide on the plant surface. In addition, the slow-release and controlled-release characteristics of the microcapsules enable the active ingredients of the pesticide to be gradually released, prolonging the duration of the drug effect, reducing the number of times of application, and reducing the amount of pesticide used.

[0030] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0031] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0032] The piperine used in the present invention was purchased from Shanghai Myrel Biochemical Technology Co., Ltd., CAS No.: 94-62-2, with a purity of 97%.

[0033] The clothianidin used in the present invention was purchased from Shandong Suihua Biotechnology Co., Ltd., CAS No.: 210880-92-5, with a purity of 98%.

[0034] The bifenthrin used in the present invention was purchased from Shandong Suihua Biotechnology Co., Ltd., CAS No.: 82657-04-3, with a purity of 98%.

[0035] In the following examples and comparative examples of the present invention, the bifenthrin-clothianidin complex is composed of bifenthrin and clothianidin in a mass ratio of 1:1.

[0036] Example 1: Preparation of pesticide microcapsules:

[0037] (1) adding 6 g of an active ingredient of a pesticide to 90 mL of ethyl acetate, and then adding 12 g of polylactic acid, stirring evenly to obtain an organic phase; the active ingredient of the pesticide is composed of a bifenthrin-thiamethoxam complex and piperine in a mass ratio of 1:2;

[0038] (2) Dissolve 4.5 g of polyvinyl alcohol in 450 mL of water to obtain an aqueous phase;

[0039] (3) In an ice-water bath, using a high-speed homogenizer, stirring at a speed of 12,000 rpm, add the organic phase dropwise into the aqueous phase and stir for 20 min to form an O / W emulsion;

[0040] (4) The O / W emulsion was stirred and evaporated at 35 °C for 2 h to remove ethyl acetate. The precipitate was collected by centrifugation (10,000 rpm, 15 min), washed three times with deionized water, and freeze-dried to obtain pesticide microcapsules.

[0041] Figure 1 This is a photo of the pesticide microcapsules prepared in this example, magnified 500 times under an electron microscope. Figure 1 It can be seen that the present application successfully prepared pesticide microcapsules.

[0042] Example 2: Preparation of pesticide microcapsules:

[0043] (1) adding 6 g of an active ingredient of a pesticide to 90 mL of ethyl acetate, and then adding 12 g of polylactic acid, stirring evenly to obtain an organic phase; the active ingredient of the pesticide is composed of a bifenthrin-thiamethoxam complex and piperine in a mass ratio of 1:1;

[0044] (2) Dissolve 4.5 g of polyvinyl alcohol in 450 mL of water to obtain an aqueous phase;

[0045] (3) In an ice-water bath, using a high-speed homogenizer, stirring at a speed of 12,000 rpm, add the organic phase dropwise into the aqueous phase and stir for 20 min to form an O / W emulsion;

[0046] (4) The O / W emulsion was stirred and evaporated at 35 °C for 2 h to remove ethyl acetate. The precipitate was collected by centrifugation (10,000 rpm, 15 min), washed three times with deionized water, and freeze-dried to obtain pesticide microcapsules.

[0047] Example 3: Preparation of pesticide microcapsules:

[0048] (1) 8 g of the active ingredient of the pesticide was added to 120 mL of ethyl acetate, and then 16 g of polylactic acid was added and stirred evenly to obtain an organic phase; the organic phase was composed of a bifenthrin-thiamethoxam complex and piperine in a mass ratio of 1:3;

[0049] (2) Dissolve 6 g of polyvinyl alcohol in 600 mL of water to obtain an aqueous phase;

[0050] (3) In an ice-water bath, using a high-speed homogenizer, stirring at a speed of 12,000 rpm, add the organic phase dropwise into the aqueous phase and stir for 20 min to form an O / W emulsion;

[0051] (4) The O / W emulsion was stirred and evaporated at 35 °C for 2 h to remove ethyl acetate. The precipitate was collected by centrifugation (10,000 rpm, 15 min), washed three times with deionized water, and freeze-dried to obtain pesticide microcapsules.

[0052] Comparative Example 1:

[0053] (1) Add 4 g of bifenthrin-thiamethoxam complex to 60 mL of ethyl acetate, and then add 8 g of polylactic acid, stir evenly, and obtain an organic phase;

[0054] (2) Dissolve 3 g of polyvinyl alcohol in 300 mL of water to obtain an aqueous phase;

[0055] (3) In an ice-water bath, using a high-speed homogenizer, stirring at a speed of 12,000 rpm, add the organic phase dropwise into the aqueous phase and stir for 20 min to form an O / W emulsion;

[0056] (4) The O / W emulsion was stirred and evaporated at 35 °C for 2 h to remove ethyl acetate. The precipitate was collected by centrifugation (10,000 rpm, 15 min), washed three times with deionized water, and freeze-dried to obtain pesticide microcapsules.

[0057] Comparative Example 2:

[0058] (1) Add 4 g of piperine to 60 mL of ethyl acetate, then add 8 g of polylactic acid and stir evenly to obtain an organic phase;

[0059] (2) Dissolve 3 g of polyvinyl alcohol in 300 mL of water to obtain an aqueous phase;

[0060] (3) In an ice-water bath, using a high-speed homogenizer, stirring at a speed of 12,000 rpm, add the organic phase dropwise into the aqueous phase and stir for 20 min to form an O / W emulsion;

[0061] (4) The O / W emulsion was stirred and evaporated at 35 °C for 2 h to remove ethyl acetate. The precipitate was collected by centrifugation (10,000 rpm, 15 min), washed three times with deionized water, and freeze-dried to obtain pesticide microcapsules.

[0062] Comparative Example 3:

[0063] (1) adding 6 g of an active ingredient of a pesticide to 90 mL of ethyl acetate, and then adding 12 g of polylactic acid, stirring evenly to obtain an organic phase; the active ingredient of the pesticide is composed of a bifenthrin-thiamethoxam complex and piperine in a mass ratio of 2:1;

[0064] (2) Dissolve 4.5 g of polyvinyl alcohol in 450 mL of water to obtain an aqueous phase;

[0065] (3) In an ice-water bath, using a high-speed homogenizer, stirring at a speed of 12,000 rpm, add the organic phase dropwise into the aqueous phase and stir for 20 min to form an O / W emulsion;

[0066] (4) The O / W emulsion was stirred and evaporated at 35 °C for 2 h to remove ethyl acetate. The precipitate was collected by centrifugation (10,000 rpm, 15 min), washed three times with deionized water, and freeze-dried to obtain pesticide microcapsules.

[0067] Comparative Example 4:

[0068] (1) adding 10 g of an active ingredient of a pesticide to 150 mL of ethyl acetate, and then adding 20 g of polylactic acid, stirring evenly to obtain an organic phase; the active ingredient of the pesticide comprises a bifenthrin-thiamethoxam complex and piperine in a mass ratio of 1:4;

[0069] (2) Dissolve 7.5 g of polyvinyl alcohol in 750 mL of water to obtain an aqueous phase;

[0070] (3) In an ice-water bath, using a high-speed homogenizer, stirring at a speed of 12,000 rpm, add the organic phase dropwise into the aqueous phase and stir for 20 min to form an O / W emulsion;

[0071] (4) The O / W emulsion was stirred and evaporated at 35 °C for 2 h to remove ethyl acetate. The precipitate was collected by centrifugation (10,000 rpm, 15 min), washed three times with deionized water, and freeze-dried to obtain pesticide microcapsules.

[0072] Comparative Example 5:

[0073] The bifenthrin-thiamethoxam complex and piperine were mixed in a mass ratio of 1:2 to prepare a pesticide preparation.

[0074] Test Example 1:

[0075] 1. Test insect source: Two-spotted spider mites were collected from a strawberry garden in Juancheng County, Shandong Province.

[0076] 2. Test methods:

[0077] 2.1 Toxicity was determined according to the test method in 1.3 of "Indoor toxicity and field efficacy test of 9 acaricides against strawberry two-spotted spider mites" (Li Jianjian et al. Journal of Northwest Agricultural Sciences, 2020).

[0078] Using the leaf dipping method, female adult mites with consistent physiological states were selected and introduced onto strawberry leaves with good growth conditions. After 2 hours, when the test mites were stable in their activities, the leaves were cut off, with 30 adult mites on each leaf. According to the results of preliminary tests, 5 dilution concentrations were set for each pesticide, along with 1 blank control with clear water. The leaves were respectively immersed in the pesticides prepared in advance, gently shaken, taken out after 5 seconds, and the excess liquid was blotted with filter paper and placed on a culture dish. To prevent the leaves from dehydrating and the two-spotted spider mites from escaping, the leaf margins were wrapped with moist absorbent cotton. Each treatment was replicated 3 times. Each treatment was placed in an artificial climate chamber at (25 ± 1) °C, with a photoperiod of 16 h (L)∶8 h (D), and a relative humidity of 60% - 70%. After 72 hours, the survival of the two-spotted spider mites was observed. By gently touching the mite body with a writing brush, those with immobile legs and no response were recorded as dead individuals.

[0079] Count the total number of mites, the number of dead mites, and the number of surviving mites in each treatment. Use statistical software to calculate the median lethal concentration (LC 50 ) and the virulence regression equation.

[0080] Mortality rate = (number of dead mites / number of test mites) × 100%;

[0081] Corrected mortality rate = (mortality rate of treatment group - mortality rate of control group) / (1 - mortality rate of control group) × 100%.

[0082] 2.2 Then, calculate the co-toxicity coefficient (CTC) of the mixture according to the Sun Yunpei method, and analyze the mixing effect based on the co-toxicity coefficient.

[0083] The calculation formula for the co-toxicity coefficient (CTC) is as follows:

[0084] Toxicity index (TI) = (LC 50 of standard pesticide / LC 50 of test pesticide) × 100;

[0085] Actual toxicity index of mixture (ATI) = (LC 50 of standard pesticide / LC 50 of mixed pesticide) × 100;

[0086] Theoretical toxicity index of mixture (TTI) = toxicity index of pesticide A × percentage content of pesticide A in the mixture + toxicity index of pesticide B × percentage content of pesticide B in the mixture;

[0087] Co-toxicity coefficient (CTC) = (ATI / TTI) × 100;

[0088] According to the classification standard of the co-toxicity coefficient (CTC), CTC ≤ 80 indicates antagonistic effect, 80 < CTC < 120 indicates additive effect, and CTC ≥ 120 indicates synergistic effect.

[0089] Table 1 Indoor toxicity test of different treatments against Tetranychus urticae

[0090]

[0091] From the results in Table 1, it can be seen that the addition of piperine to the mixture of bifenthrin-thiamethoxam complex and piperine enhances the insecticidal effect of bifenthrin and clothianidin, achieving a synergistic effect of 1+1>2. The co-toxicity coefficient (CTC) of the bifenthrin-thiamethoxam complex and piperine in the mass ratio range of 1:1-3 is greater than 120, and the synergistic effect is significant, and the insecticidal effect on two-spotted spider mites is good, of which 1:2 is the best ratio. In addition, in Comparative Example 5 and Example 1, the mass ratio of the bifenthrin-thiamethoxam complex and piperine is 1:2, but the synergistic effect of Example 1 is stronger than that of Comparative Example 5, LC 50 It is also lower, indicating that microencapsulation enhances the synergistic effect between the bifenthrin-thiamethoxam complex and piperine, reduces the amount of pesticide used, and improves the insecticidal effect against two-spotted spider mites.

[0092] Test Example 2: Field test of pesticide microcapsules for controlling chrysanthemum aphids:

[0093] The test crop was multi-headed chrysanthemum, and the control target was chrysanthemum aphids. The test was set up at the Xihouxian chrysanthemum planting base in Shijiazhuang City, and the plots where chrysanthemum aphids were evenly distributed were used as the test sites. A total of 4 treatment groups were set up in the test, and the pesticide microcapsules prepared in Example 1, the pesticide microcapsules prepared in Comparative Examples 1-2, and the pesticide preparation prepared in Comparative Example 5 were applied respectively. A blank control group was also set up. Each treatment was repeated 3 times, and the area of ​​each plot was 20m 2 , a total of 15 communities.

[0094] The pesticide microcapsules prepared in Example 1, the pesticide microcapsules prepared in Comparative Examples 1-2, and the pesticide preparation prepared in Comparative Example 5 were diluted 1000 times respectively, and clean water was used as a control. They were evenly sprayed with an electric sprayer, and the number of aphids was investigated before spraying, and the number of aphids remaining on the whole plant was investigated 1 and 7 days after spraying.

[0095] Survey and statistical methods: sampling was carried out at five diagonal points in the experimental plot, 4 plants were fixed at each point, and 3 leaves at the top, middle and bottom of each plant were fixed. A total of 20 plants and 60 leaves were fixed for investigation, and the number of live aphids was investigated and recorded.

[0096] Control effect (%) = [1-(number of insects in blank control group before medication × number of insects in treated group after medication) / (number of insects in blank control group after medication × number of insects in treated group before medication)] × 100.

[0097] Table 2 Control effects of different treatments

[0098]

[0099] Figure 2 and Figure 3 All of them are pictures of the pesticide microcapsules prepared in Example 1 one day after application. It can be seen from the pictures that chrysanthemum aphids begin to fall off after application, indicating that the prepared pesticide microcapsules can have a significant effect on chrysanthemum aphids within a short period of time after application.

[0100] As shown in Table 2, the test results show that the pesticide microcapsules prepared in Example 1 achieved a control effect of 93.5% after 1 day, and the effect was further improved to 98.6% after 7 days. This shows that the pesticide microcapsules prepared in Example 1 have a rapid and sustained insecticidal effect. The pesticide microcapsules prepared in Comparative Example 1 have only the active ingredient of the bifenthrin-thiamethoxam complex, and the control effect is relatively low, which is 79.2% after 1 day and 81.5% after 7 days. Although bifenthrin and clothianidin have insecticidal effects, their single complex formula may not be as broad-spectrum and persistent as the multi-component microcapsules of Example 1. The pesticide microcapsules prepared in Comparative Example 2 have only piperine as the active ingredient, and the control effect on chrysanthemum aphids is relatively low, which is 48.2% after 1 day and only 51.8% after 7 days. Although piperine has a certain repellent or inhibitory effect on some pests, its insecticidal effect is limited. Although the bifenthrin-thiamethoxam complex and piperine were directly mixed in Comparative Example 5, the microencapsulation technology was not used, resulting in a control effect of 91.2% after 1 day and 92.1% after 7 days. Although the direct mixing provides a higher initial insecticidal effect, due to the lack of sustained-release protection of the microcapsules, the efficacy gradually weakens over time, and it is difficult to achieve the persistence of the pesticide microcapsules prepared in Example 1.

[0101] In summary, the test results show that the pesticide microcapsules prepared in Example 1 have significant control effects. The advantages lie in the sustained-release effect and stability brought by the microcapsule technology, which enables the active ingredients to be stably released over a long period of time, thereby showing excellent insecticidal effects after 1 day and 7 days.

[0102] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pesticide microcapsule, characterized in that: Prepared by the following method: (1) adding an active ingredient of a pesticide to ethyl acetate, and then adding polylactic acid, stirring evenly to obtain an organic phase; the active ingredient of the pesticide is composed of a bifenthrin-thiamethoxam complex and piperine in a mass ratio of 1:2; (2) dissolving polyvinyl alcohol in water to obtain an aqueous phase; (3) In an ice-water bath, the organic phase is added dropwise to the aqueous phase while stirring to form an emulsion; (4) stirring the emulsion to evaporate the ethyl acetate, collecting the precipitate by centrifugation, washing, and freeze-drying to obtain pesticide microcapsules; In step (1), the bifenthrin-clothianidin complex is composed of bifenthrin and clothianidin in a mass ratio of 1:1; In step (1), the ratio of the added amount of the pesticide active ingredient to that of ethyl acetate is 1 g: (8-15) mL; In step (1), the mass ratio of the pesticide active ingredient to the polylactic acid is 1:(1.5-2.5); In step (3), the volume ratio of the organic phase to the aqueous phase is 1:(4-10); The pesticide microcapsules are used to control spider mites or chrysanthemum aphids.

2. The pesticide microcapsule according to claim 1, characterized in that: In step (2), the mass concentration of polyvinyl alcohol in the aqueous phase is 0.5%-2%.

3. The pesticide microcapsule according to claim 1, characterized in that: In step (3), the stirring speed is 10000-15000 rpm, and the stirring time is 10-30 min.

4. The pesticide microcapsule according to claim 1, characterized in that: In step (4), the temperature of stirring and evaporating is 25-40° C. and the time is 1-3 h.

5. Use of the pesticide microcapsule according to any one of claims 1 to 4 in controlling two-spotted spider mites or chrysanthemum aphids.

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