Environment-friendly compound emulsion in water for crop pest killing and preparation process of environment-friendly compound emulsion in water

Abstract

The invention relates to an environment-friendly compound emulsion in water for crop pest killing and a preparation process thereof, and belongs to the technical field of pesticides. The preparation process specifically comprises the following steps: compounding a plant extract, plant essential oil, a solvent and an emulsifier into an organic phase, mixing deionized water, an anti-freezing agent, a thickening agent and a defoaming agent to obtain a water phase, adding the water phase into the organic phase under high-speed stirring, continuously stirring to obtain an emulsion, and carrying out spray drying to obtain the environment-friendly compound emulsion in water. And performing ultrasonic treatment to prepare the environment-friendly compound emulsion in water. The plant extract and the plant essential oil repel and kill crop pests from multiple dimensions of a respiratory system, a nervous system, a digestive system and growth and development, not only can the drug resistance of the pests be reduced, but also environmental pollution and pesticide residues are avoided, and in addition, benzalophore 30 is selected as an emulsifier, so that the stability and insecticidal activity of the emulsion in water are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticides and relates to an environmentally friendly composite aqueous emulsion for killing insects in crops and a preparation process thereof. Background Art

[0002] The problem of crop diseases and pests is becoming increasingly serious worldwide, becoming a serious challenge that plagues agricultural production. As the main source of food for humans, the yield and quality of crops are directly related to the survival and development of billions of people around the world. However, diseases and pests seriously threaten the healthy growth of crops and reduce the yield and quality of crops. Large-scale outbreaks of diseases and pests not only cause large-scale crop failures, but also directly affect farmers' livelihoods. In order to resist diseases and pests, farmers often use a large amount of pesticides and fertilizers, resulting in farmland soil pollution, threats to water sources, and even affecting the balance of the ecosystem. The abuse of pesticides not only harms soil microorganisms, but may also cause the death of non-target organisms, affecting the stability of the entire ecological chain. The spread of diseases and pests is also affected by factors such as climate change. Global warming may cause some diseases and pests to appear in areas that were originally unsuitable, increasing the possibility of disease and pest spread and infection, which not only threatens crop growth, but also damages the stability of the ecosystem.

[0003] Since chemically synthesized pesticides have caused prominent problems such as pollution, poisoning, pest resistance, and rampant in use, new environmentally friendly pesticides are sought in natural products. So far, three main types of environmentally friendly pesticides have been proposed, including microbial sources, plant sources, and insect regulators. They have the advantages of light pollution, low toxicity, and some drugs have high selectivity. Botanical pesticides are prepared by extracting certain parts of plants containing insecticidal active substances or active ingredients, and have the ability to repel and kill pests, but these drugs are not very ideal for eliminating pests. Therefore, the environmentally friendly composite aqueous emulsion for crop pest control provided by the present invention and its preparation process can effectively solve the above problems. Summary of the invention

[0004] The present invention relates to an environmentally friendly composite water emulsion for crop pest control and a preparation process thereof, and belongs to the technical field of pesticides. The preparation process of the environmentally friendly composite water emulsion for crop pest control disclosed in the present invention is specifically as follows: a plant extract, a plant essential oil, a solvent and an emulsifier are compounded into an organic phase, deionized water, an antifreeze agent, a thickener and a defoamer are mixed to obtain an aqueous phase, the aqueous phase is added to the organic phase under high-speed stirring, and an emulsion is obtained by continuous stirring, and then an environmentally friendly composite water emulsion is made by ultrasound. Both plant extracts and plant essential oils repel and eliminate crop pests from multiple dimensions such as the respiratory system, the nervous system, the digestive system and growth and development, which can reduce the resistance of pests to drugs, and will not cause environmental pollution and pesticide residues. In addition, benzyl 30 is selected as an emulsifier to ensure the stability and insecticidal activity of the water emulsion.

[0005] The purpose of the present invention can be achieved through the following technical solutions: An environmentally friendly composite aqueous emulsion for crop pest control comprises the following raw materials in parts by weight: 10-20 parts of plant extract, 2-4 parts of plant essential oil, 30-40 parts of solvent, and 5-10 parts of emulsifier. The plant extract consists of a celastrus granatum extract, a chinaberry seed extract, and a derris vine extract in a mass ratio of 1:1-2:1-3; and the plant essential oil consists of a thyme essential oil, aniseed essential oil, and clove essential oil in a mass ratio of 1-2:1:2.

[0006] Furthermore, the preparation method of the neem seed extract comprises the following steps: (1) drying neem seeds, grinding and sieving to obtain powder, adding alkaline solution, mixing and soaking, and filtering to obtain filtrate and filter residue; (2) drying the filter residue into a residue powder, adding an organic solvent for extraction, and filtering to obtain an organic solvent extract; (3) extracting the filtrate in step (1) with an organic solvent extract, collecting the extract phase by standing and stratifying, then heating and distilling the organic solvent in the extract phase, concentrating the remaining liquid under reduced pressure, and drying it into powder to obtain the neem seed extract.

[0007] Furthermore, the mesh size of the sieve in step (1) is 100-300 mesh, the ratio of the powder to the alkaline solution is 1-5g:20-30mL, wherein the alkaline solution refers to a sodium bicarbonate solution with a mass fraction of 3-5%, and the soaking refers to soaking at room temperature for 3-5h.

[0008] Furthermore, in the step (2), the ratio of slag powder to organic solvent is 3-5 g:12-16 mL, wherein the organic solvent is ether, and the organic solvent extraction refers to extraction at room temperature for 1-2 h.

[0009] Furthermore, in the step (3), the volume ratio of the organic solvent extract to the filtrate is 1-1.2:1, the extraction time is 20-30 min, the temperature and time of the heating distillation are 40-42° C. and 30-40 min, respectively, the pressure of the reduced pressure concentration is -0.06~-0.08 MPa, and the temperature and time of the drying are 40-50° C. and 1-2 h, respectively.

[0010] A method for preparing an environmentally friendly composite aqueous emulsion for crop pest control, the method comprising the following steps: A1: Plant extract, plant essential oil, solvent and emulsifier are mixed and heated, and then stirred at high speed to form an organic phase; A2: deionized water, antifreeze agent, thickener and defoamer are mixed to obtain an aqueous phase; A3: The aqueous phase is added to the organic phase under high-speed stirring, and the stirring is continued to form an emulsion. After ultrasonication on a high-speed ultrasonic homogenizer, an environmentally friendly compound aqueous emulsion for crop insecticide is obtained.

[0011] Furthermore, in the step A1, the heating temperature is 50-60° C., the rotation speed and time of the high-speed stirring are 1300-1500 r / min and 10-15 min respectively, the solvent is methanol, and the emulsifier is benzyl 30.

[0012] Furthermore, in step A2, the mass ratio of deionized water, antifreeze agent, thickener and defoamer is 40-50:1-2:1-3:0.5-1.

[0013] Furthermore, in step A3, the volume ratio of the aqueous phase to the organic phase is 1-3:1, the rotation speed of the high-speed stirring is 1300-1500 r / min, the continuous stirring time is 20-30 min, and the ultrasonic time is 10-20 min.

[0014] Beneficial effects of the present invention: 1. The plant extracts of the present invention are celangulan extract, chinaberry seed extract and derris vine extract. The substance with high insecticidal activity in the celangulan extract is celangulin V, which acts on the digestive system, can change the intestinal cell membrane structure of the pest, and then destroy the membrane system, leading to excessive blood loss and death; the alkaloids in the chinaberry seed extract mainly inhibit the appetite of the pest and destroy the motor system; the derris vine extract destroys the nervous system, causing the pest to become excited, convulsed, paralyzed and die, and is combined with thyme essential oil, star anise essential oil and clove essential oil to repel and eliminate crop pests from multiple dimensions of respiratory system, nervous system, digestive system and growth and development, and enhances the pest disinfecting effect and expands the pest disinfecting range; 2. The neem seeds are extracted with sodium bicarbonate solution and then extracted with an organic solvent to form a double extraction process, thereby improving the extraction effect of the neem seeds; 3. The aqueous emulsion is a heterogeneous dispersion system. The present invention obtains a higher Zeta potential by adding benzyl 30. The electrostatic repulsion of the double electric layer is dominant, which avoids the mutual attraction between the dispersed droplets and aggregation and sedimentation, thereby ensuring the stability of the system. DETAILED DESCRIPTION

[0015] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with embodiments.

[0016] The celastrus angulatus extract in all embodiments and comparative examples of the present invention was purchased from Gansu Yishengxiang Biotechnology Co., Ltd.; the derris vine extract was purchased from Shaanxi Bolin Biotechnology Co., Ltd. with the item number BL-20231113002; thyme essential oil was purchased from Guangzhou Fuzhiyuan Biotechnology Co., Ltd.; star anise essential oil was purchased from Hubei Xinghengye Technology Co., Ltd.; clove essential oil was purchased from Jiangxi Jingwang Natural Flavor Co., Ltd. with the item number JW-08, the antifreeze agent was methanol, the thickener was purchased from Yixing Jiateng Chemical Co., Ltd., and the defoaming agent was purchased from Shanghai Ziyi Chemical Co., Ltd.

[0017] Example 1 An environmentally friendly composite aqueous emulsion for crop pest control, comprising the following raw materials in parts by weight: 10 parts of plant extract, 2 parts of plant essential oil, 30 parts of solvent, and 5 parts of emulsifier, wherein the plant extract consists of a celastrus granatum extract, a chinaberry seed extract, and a derris vine extract in a mass ratio of 1:1:1, and the plant essential oil consists of a thyme essential oil, aniseed essential oil, and clove essential oil in a mass ratio of 1:1:2.

[0018] The preparation method of the neem seed extract comprises the following steps: (1) drying neem seeds, grinding and sieving to obtain powder, adding alkaline solution, mixing and soaking, and filtering to obtain filtrate and filter residue; (2) drying the filter residue into a residue powder, adding an organic solvent for extraction, and filtering to obtain an organic solvent extract; (3) extracting the filtrate in step (1) with an organic solvent extract, collecting the extract phase by standing and stratifying, then heating and distilling the organic solvent in the extract phase, concentrating the remaining liquid under reduced pressure, and drying it into powder to obtain the neem seed extract.

[0019] The mesh size of the sieve in the step (1) is 100 mesh, the ratio of the powder to the alkaline solution is 1 g:20 mL, wherein the alkaline solution refers to a sodium bicarbonate solution with a mass fraction of 3%, and the soaking refers to soaking at room temperature for 3 hours.

[0020] In the step (2), the ratio of slag powder to organic solvent is 3g:12mL, wherein the organic solvent is ether, and the organic solvent extraction refers to extraction at room temperature for 1 hour.

[0021] In the step (3), the volume ratio of the organic solvent extract to the filtrate is 1:1, the extraction time is 20 minutes, the temperature and time of the heating distillation are 40°C and 30 minutes respectively, the pressure of the reduced pressure concentration is -0.06MPa, and the temperature and time of the drying are 40°C and 1 hour respectively.

[0022] A method for preparing an environmentally friendly composite aqueous emulsion for crop pest control, the method comprising the following steps: A1: Plant extract, plant essential oil, solvent and emulsifier are mixed and heated, and then stirred at high speed to form an organic phase; A2: deionized water, antifreeze agent, thickener and defoamer are mixed to obtain an aqueous phase; A3: The aqueous phase is added to the organic phase under high-speed stirring, and the stirring is continued to form an emulsion. After ultrasonication on a high-speed ultrasonic homogenizer, an environmentally friendly compound aqueous emulsion for crop insecticide is obtained.

[0023] The heating temperature in step A1 is 50° C., the rotation speed and time of the high-speed stirring are 1300 r / min and 10 min respectively, the solvent is methanol, and the emulsifier is benzyl 30.

[0024] The mass ratio of deionized water, antifreeze agent, thickener and defoamer in step A2 is 40:1:1:0.5.

[0025] In the step A3, the volume ratio of the aqueous phase to the organic phase is 1:1, the rotation speed of the high-speed stirring is 1300 r / min, the continuous stirring time is 20 min, and the ultrasonic time is 10 min.

[0026] The benzyl 30 was purchased from Haian Petrochemical Plant, Jiangsu Province, CAS: 9002-92-0.

[0027] Example 2 An environmentally friendly composite aqueous emulsion for crop pest control, comprising the following raw materials in parts by weight: 15 parts of plant extract, 3 parts of plant essential oil, 35 parts of solvent, and 7 parts of emulsifier, wherein the plant extract consists of a celastrus granatum extract, a chinaberry seed extract, and a derris vine extract in a mass ratio of 1:1.5:2, and the plant essential oil consists of a thyme essential oil, aniseed essential oil, and clove essential oil in a mass ratio of 1.5:1:2.

[0028] The preparation method of the neem seed extract comprises the following steps: (1) drying neem seeds, grinding and sieving to obtain powder, adding alkaline solution, mixing and soaking, and filtering to obtain filtrate and filter residue; (2) drying the filter residue into a residue powder, adding an organic solvent for extraction, and filtering to obtain an organic solvent extract; (3) extracting the filtrate in step (1) with an organic solvent extract, collecting the extract phase by standing and stratifying, then heating and distilling the organic solvent in the extract phase, concentrating the remaining liquid under reduced pressure, and drying it into powder to obtain the neem seed extract.

[0029] The mesh size of the sieve in the step (1) is 200 mesh, the ratio of the powder to the alkaline solution is 3g:25mL, wherein the alkaline solution refers to a sodium bicarbonate solution with a mass fraction of 4%, and the soaking refers to soaking at room temperature for 4 hours.

[0030] In the step (2), the ratio of slag powder to organic solvent is 4 g:14 mL, wherein the organic solvent is ether, and the organic solvent extraction refers to extraction at room temperature for 1.5 h.

[0031] In the step (3), the volume ratio of the organic solvent extract to the filtrate is 1.1:1, the extraction time is 25 minutes, the temperature and time of the heating distillation are 41°C and 35 minutes respectively, the pressure of the reduced pressure concentration is -0.07MPa, and the temperature and time of the drying are 45°C and 1.5h respectively.

[0032] A method for preparing an environmentally friendly composite aqueous emulsion for crop pest control, the method comprising the following steps: A1: Plant extract, plant essential oil, solvent and emulsifier are mixed and heated, and then stirred at high speed to form an organic phase; A2: deionized water, antifreeze agent, thickener and defoamer are mixed to obtain an aqueous phase; A3: The aqueous phase is added to the organic phase under high-speed stirring, and the stirring is continued to form an emulsion. After ultrasonication on a high-speed ultrasonic homogenizer, an environmentally friendly compound aqueous emulsion for crop insecticide is obtained.

[0033] The heating temperature in step A1 is 55° C., the rotation speed and time of the high-speed stirring are 1400 r / min and 12 min respectively, the solvent is methanol, and the emulsifier is benzyl alcohol 30.

[0034] The mass ratio of deionized water, antifreeze agent, thickener and defoamer in step A2 is 45:1.5:2:0.8.

[0035] In the step A3, the volume ratio of the aqueous phase to the organic phase is 2:1, the rotation speed of the high-speed stirring is 1400 r / min, the continuous stirring time is 25 min, and the ultrasonic time is 15 min.

[0036] The benzyl 30 was purchased from Haian Petrochemical Plant, Jiangsu Province, CAS: 9002-92-0.

[0037] Example 3 An environmentally friendly composite aqueous emulsion for crop pest control, comprising the following raw materials in parts by weight: 20 parts of plant extract, 4 parts of plant essential oil, 40 parts of solvent, and 10 parts of emulsifier, wherein the plant extract consists of a celastrus granatum extract, a chinaberry seed extract, and a derris vine extract in a mass ratio of 1:2:3, and the plant essential oil consists of a thyme essential oil, aniseed essential oil, and clove essential oil in a mass ratio of 2:1:2.

[0038] The preparation method of the neem seed extract comprises the following steps: (1) drying neem seeds, grinding and sieving to obtain powder, adding alkaline solution, mixing and soaking, and filtering to obtain filtrate and filter residue; (2) drying the filter residue into a residue powder, adding an organic solvent for extraction, and filtering to obtain an organic solvent extract; (3) extracting the filtrate in step (1) with an organic solvent extract, collecting the extract phase by standing and stratifying, then heating and distilling the organic solvent in the extract phase, concentrating the remaining liquid under reduced pressure, and drying it into powder to obtain the neem seed extract.

[0039] The mesh size of the sieve in the step (1) is 300 mesh, the ratio of the powder to the alkaline solution is 5g:30mL, wherein the alkaline solution refers to a sodium bicarbonate solution with a mass fraction of 5%, and the soaking refers to soaking at room temperature for 5 hours.

[0040] In the step (2), the ratio of slag powder to organic solvent is 5 g:16 mL, wherein the organic solvent is ether, and the organic solvent extraction refers to extraction at room temperature for 2 hours.

[0041] In the step (3), the volume ratio of the organic solvent extract to the filtrate is 1.2:1, the extraction time is 30 minutes, the temperature and time of the heating distillation are 42°C and 40 minutes respectively, the pressure of the reduced pressure concentration is -0.08MPa, and the temperature and time of the drying are 50°C and 2 hours respectively.

[0042] A method for preparing an environmentally friendly composite aqueous emulsion for crop pest control, the method comprising the following steps: A1: Plant extract, plant essential oil, solvent and emulsifier are mixed and heated, and then stirred at high speed to form an organic phase; A2: deionized water, antifreeze agent, thickener and defoamer are mixed to obtain an aqueous phase; A3: The aqueous phase is added to the organic phase under high-speed stirring, and the stirring is continued to form an emulsion. After ultrasonication on a high-speed ultrasonic homogenizer, an environmentally friendly compound aqueous emulsion for crop insecticide is obtained.

[0043] The heating temperature in step A1 is 60° C., the rotation speed and time of the high-speed stirring are 1500 r / min and 15 min respectively, the solvent is methanol, and the emulsifier is benzyl 30.

[0044] The mass ratio of deionized water, antifreeze agent, thickener and defoamer in step A2 is 50:2:3:1.

[0045] In the step A3, the volume ratio of the aqueous phase to the organic phase is 3:1, the rotation speed of the high-speed stirring is 1500 r / min, the continuous stirring time is 30 min, and the ultrasonic time is 20 min.

[0046] The benzyl 30 was purchased from Haian Petrochemical Plant, Jiangsu Province, CAS: 9002-92-0.

[0047] Comparative Example 1 On the basis of Example 2, the Celastrus angulatus extract in the plant extract was removed and replaced with an equal mass of Melia azedarach seed extract, and other conditions were consistent with Example 2.

[0048] Comparative Example 2 On the basis of Example 2, the Melia azedarach seed extract in the plant extract was removed and replaced with an equal mass of Celastrus angulatus extract, and other conditions were consistent with Example 2.

[0049] Comparative Example 3 On the basis of Example 2, the Derris dahurica extract in the plant extract was removed and replaced with an equal mass of Melia azedarach seed extract, and other conditions were consistent with Example 2.

[0050] Comparative Example 4 On the basis of Example 2, the plant extract in the raw material was removed and replaced with an equal weight portion of plant essential oil, and other conditions were consistent with Example 2.

[0051] Comparative Example 5 On the basis of Example 2, the plant essential oil in the raw material was removed and replaced with an equal weight portion of plant extract, and other conditions were consistent with Example 2.

[0052] Comparative Example 6 Based on Example 2, the difference of Comparative Example 6 is that benzyl 35 is used to replace benzyl 30, and other conditions are consistent with Example 2.

[0053] The benzyl 35 was purchased from Nantong Arches Chemical Co., Ltd., CAS: 9002-92-0.

[0054] Comparative Example 7 On the basis of Example 2, the added weight portion of the emulsifier is 2 parts, and the other conditions are consistent with Example 2.

[0055] Comparative Example 8 On the basis of Example 2, the added weight portion of the emulsifier is 12 parts, and the other conditions are consistent with Example 2.

[0056] Performance Testing: Insecticidal test: The environmentally friendly composite aqueous emulsions for crop insecticide obtained in Examples 1-3 and Comparative Examples 1-8 were mixed and diluted with water, and the mass concentration after dilution was 0.3% and used as samples. In addition, a high-efficiency insecticide composition was obtained according to the preparation method of Example 1 in Patent CN103355300B, which was configured into a solution with a mass concentration of 0.3% and recorded as a control group. The test crop was rice, and the target organisms were Chilo suppressalis and Rice borer. Test site conditions: The test site is located at the paddy field test station of Raohe Farm. The rice seedling size is 30 cmx14 cm. An area of ​​12 mu is randomly selected for the insecticide test of the sample and control group. Application time: The application period is 3 days before rice burst (late booting stage). The day of application is sunny and cloudy, with a temperature of 24.4℃ and a speed of 2.0m / s. Application equipment and methods: Use a backpack manual sprayer, use 100mL of sample per mu of land, dilute to 15kg with clean water, keep the nozzle 30cm away from the crop surface, and spray in a fan-shaped area to ensure that all crops are sprayed; Calculation method of drug efficacy: The first survey is to investigate the number of white ears, the number of rice borers and rice planthoppers 7 days after full heading, and calculate the control effect. The second survey is conducted 30 days after application, and the content is consistent with the first survey, and the control effect is calculated. Pest survey method: 5 points of treatment and control are sampled by diagonal method, and 20 holes are continuously surveyed at each point to investigate the number of white ears (striped stem borer) and the number of rice borers, and calculate the control effect; Calculation method of drug efficacy: Control effect % = (ab) / a×100; a is the initial number of insects, and b is the number of insects in the pesticide-treated area after spraying.

[0057] The above test results are shown in Table 1 and Table 2.

[0058] Table 1 Results of the first survey on control effect test

[0059] Table 2 Results of the second survey on control effect test

[0060] From the analysis of Table 1 and Table 2, it can be concluded that the control effects of Examples 1-3 are better than those of Comparative Examples 1-8, and the control effects of the Examples and the control group are both 100% in the first survey, and the control effects of the Examples in the second survey are all about 95%, while the control effect of the rice borer in the control group is still 100%, and the control effect of the striped stem borer is 96.3%, so it can be seen that the control effects of the Examples are equivalent to those of the control group; in addition, the control effect of the comparative example in the first survey is better than the control effect of the second survey. In Comparative Examples 1-3, by removing one of the extracts of Caulis angelicae, Melia azedarach and Derris chinensis, the disinfecting effect on the striped stem borer and rice borer was significantly reduced; in Comparative Examples 4-5, by removing the plant extracts or plant essential oils, the disinfecting effect on the striped stem borer and rice borer was the worst; in Comparative Example 6, the stability of the system formed by replacing Benzene Ze 30 with Benzene Ze 35 decreased, affecting the efficacy of the aqueous emulsion; in Comparative Examples 7-8, the amount of Benzene Ze 30 added exceeded the range of the embodiments, affecting the stability of the system and making the efficacy of the aqueous emulsion worse.

[0061] Stability test: The environmentally friendly composite aqueous emulsions for crop pest control obtained in Examples 1-3 and Comparative Examples 6-8 were used as samples. According to GB-T1603-2001, a stability test was performed, 100 mL of standard hard water was added to a 500 mL beaker and stirred at a uniform speed, 0.5 mL of the sample was accurately drawn and slowly dripped into the hard water to prepare a 100 mL aqueous emulsion dilution emulsion. After the dripping, the mixture was transferred to a 100 mL measuring cylinder by stirring for 30 seconds, and the measuring cylinder was placed in a constant temperature water bath at 30°C and kept at the temperature for 1 hour. The dilution was taken out to directly observe and detect the physical properties of the emulsion, and the Malvemm-NanoZSE particle size potential detector was used to measure the samples respectively, and the average value was taken for three measurements of each group of samples. The test results are shown in Table 3.

[0062] Table 3 Stability test results

[0063] It can be seen from Table 3 that the appearance of the embodiment and comparative examples 6-8 are milky white liquids, the emulsification and dispersibility of the embodiment are qualified, and the absolute value of the Zeta potential is greater than that of comparative examples 6-8. The absolute value of the Zeta potential of comparative example 6 decreases by replacing benzene 30 with benzene 35, and the absolute value of the Zeta potential of comparative examples 7-8 decreases by increasing or decreasing the amount of benzene 30 added.

[0064] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An environmentally friendly composite aqueous emulsion for crop pest control, characterized in that: The environmentally friendly composite aqueous emulsion for crop pest control comprises the following raw materials in parts by weight: 10-20 parts of plant extract, 2-4 parts of plant essential oil, 30-40 parts of solvent, and 5-10 parts of emulsifier. The plant extract consists of a celastrus granatum extract, a chinaberry seed extract, and a derris vine extract in a mass ratio of 1:1-2:1-3; and the plant essential oil consists of a thyme essential oil, aniseed essential oil, and clove essential oil in a mass ratio of 1-2:1:

2.

2. The environmentally friendly composite aqueous emulsion for crop pest control according to claim 1, characterized in that: The preparation method of the neem seed extract comprises the following steps: (1) drying neem seeds, grinding and sieving to obtain powder, adding alkaline solution, mixing and soaking, and filtering to obtain filtrate and filter residue; (2) drying the filter residue into a residue powder, adding an organic solvent for extraction, and filtering to obtain an organic solvent extract; (3) extracting the filtrate in step (1) with an organic solvent extract, collecting the extract phase by standing and stratifying, then heating and distilling the organic solvent in the extract phase, concentrating the remaining liquid under reduced pressure, and drying it into powder to obtain the neem seed extract.

3. The environmentally friendly composite aqueous emulsion for crop pest control according to claim 2, characterized in that: The mesh size of the sieve in the step (1) is 100-300 mesh, the ratio of the powder to the alkaline solution is 1-5g:20-30mL, wherein the alkaline solution refers to a sodium bicarbonate solution with a mass fraction of 3-5%, and the soaking refers to soaking at room temperature for 3-5h.

4. The environmentally friendly composite aqueous emulsion for crop pest control according to claim 2, characterized in that: In the step (2), the ratio of slag powder to organic solvent is 3-5 g:12-16 mL, wherein the organic solvent is ether, and the organic solvent extraction refers to extraction at room temperature for 1-2 hours.

5. The environmentally friendly composite aqueous emulsion for crop pest control according to claim 2, characterized in that: In the step (3), the volume ratio of the organic solvent extract to the filtrate is 1-1.2:1, the extraction time is 20-30 min, the temperature and time of the heating distillation are 40-42° C. and 30-40 min, respectively, the pressure of the reduced pressure concentration is -0.06~-0.08 MPa, and the temperature and time of the drying are 40-50° C. and 1-2 h, respectively.

6. A method for preparing an environmentally friendly composite aqueous emulsion for crop pest control according to any one of claims 1 to 5, characterized in that: The preparation method of the environmentally friendly composite aqueous emulsion for crop pest control comprises the following steps: A1: Plant extract, plant essential oil, solvent and emulsifier are mixed and heated, and then stirred at high speed to form an organic phase; A2: deionized water, antifreeze agent, thickener and defoamer are mixed to obtain an aqueous phase; A3: The aqueous phase is added to the organic phase under high-speed stirring, and the stirring is continued to form an emulsion. After ultrasonication on a high-speed ultrasonic homogenizer, an environmentally friendly compound aqueous emulsion for crop insecticide is obtained.

7. The method for preparing an environmentally friendly composite aqueous emulsion for crop pest control according to claim 6, characterized in that: The heating temperature in step A1 is 50-60° C., the rotation speed and time of the high-speed stirring are 1300-1500 r / min and 10-15 min, respectively, the solvent is methanol, and the emulsifier is benzyl 30.

8. The method for preparing an environmentally friendly composite aqueous emulsion for crop pest control according to claim 6, characterized in that: In the step A2, the mass ratio of deionized water, antifreeze agent, thickener and defoamer is 40-50:1-2:1-3:0.5-1.

9. The method for preparing an environmentally friendly composite aqueous emulsion for crop pest control according to claim 6, characterized in that: In the step A3, the volume ratio of the aqueous phase to the organic phase is 1-3:1, the rotation speed of the high-speed stirring is 1300-1500 r / min, the continuous stirring time is 20-30 min, and the ultrasonic time is 10-20 min.

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