Botanical insecticide as well as preparation method and application thereof

Abstract

The invention provides a botanical insecticide as well as a preparation method and application thereof, and belongs to the technical field of insecticides. The botanical insecticide comprises effective components and an auxiliary agent, the effective components comprise the following raw materials in parts by weight: 5-10 parts of toosendanin, 2-4 parts of crotonic acid and 4-8 parts of a Chinese tallow tree extract; the auxiliary agent is prepared from the following raw materials in parts by weight: 40 to 50 parts of methyl oleate, 2 to 5 parts of pesticide emulsifier 500 #, 5 to 10 parts of organic silicon surfactant L-775 and 5 to 10 parts of EL-90. According to the invention, the botanical insecticidal components including toosendanin, crotonic acid and sapium sebiferum extract are compounded with methyl oleate, pesticide emulsifier 500 and organic silicon surfactants L-77 and EL-90, so that the synergistic effect is obvious, and the broad-spectrum insecticidal effect is achieved. The insecticide is non-toxic to human and livestock, is environment-friendly, and is beneficial to improving the quality of agricultural products.

Description

Technical Field

[0001] This invention belongs to the field of insecticide technology, and particularly relates to a plant-derived insecticide, its preparation method, and its application. Background Technology

[0002] In modern agricultural production, pest control is a crucial link in ensuring crop yield and quality. For a long time, chemically synthesized pesticides have been widely used in agriculture due to their high efficiency and rapid insecticidal effect. However, the extensive use of chemical pesticides has brought about a series of serious problems: on the one hand, their high toxicity harms non-target organisms (such as bees and natural enemy insects), disrupting the ecological balance; on the other hand, pests are constantly developing resistance to chemical pesticides, leading to a continuous increase in the dosage and frequency of application, creating a vicious cycle. Furthermore, the residue problem of chemical pesticides directly threatens food safety, affects human health, and causes long-term pollution of soil, water bodies, and other environmental elements, exacerbating ecological degradation.

[0003] Plant-derived insecticides, as a green and environmentally friendly alternative, have received widespread attention in recent years due to their natural, low-toxicity, easily degradable, and low-prone-to-resistance properties. Plant-derived insecticides are mainly derived from the roots, stems, leaves, flowers, and fruits of plants. Their active ingredients, such as terpenes, alkaloids, flavonoids, and polyphenols, exert their control effects on pests through various mechanisms of action, including contact, stomach poisoning, antifeedant effects, and growth inhibition. However, there are still many limitations in the practical application of plant-derived insecticides: First, most plant-derived insecticides have low levels of active ingredients, resulting in insufficient insecticidal activity when used alone, making it difficult to achieve ideal control effects; second, the active ingredients have poor stability and are easily degraded by environmental factors such as light and temperature, leading to a short product shelf life; third, the current extraction processes for plant-derived insecticides are relatively crude, resulting in low extraction efficiency and poor component selectivity, leading to resource waste and high production costs; fourth, some plant-derived insecticides have a narrow spectrum of action, only effective against a few types of pests, failing to meet diverse control needs.

[0004] Therefore, developing a new plant-derived insecticide with significant insecticidal effect and wide applicability is of great practical significance for promoting green agriculture and reducing dependence on chemical pesticides. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a plant-derived insecticide with significant synergistic effects and broad-spectrum insecticidal efficacy.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A plant-derived insecticide includes an active ingredient and adjuvants; the active ingredient, by weight, comprises the following raw materials: 5-10 parts of azadirachtin, 2-4 parts of croton oleic acid, and 4-8 parts of tallow tree extract; the adjuvants, by weight, comprise the following raw materials: 40-50 parts of methyl oleate, 2-5 parts of agricultural emulsion 500, 5-10 parts of organosilicon surfactant L-775, and 10 parts of EL-905.

[0008] Preferably, the mass ratio of the active ingredient to the adjuvant is 1:(16-24).

[0009] Preferably, the preparation method of the Chinese tallow tree extract includes: drying fresh Chinese tallow tree leaves and pulverizing them to obtain Chinese tallow tree leaf powder; mixing the Chinese tallow tree leaf powder with an ethanol solution with a volume fraction of 70% to 80%, ultrasonically extracting, centrifuging the extract to collect the supernatant; concentrating the supernatant and drying it to obtain the Chinese tallow tree extract.

[0010] Preferably, the powdered Chinese tallow tree leaves are mixed with an ethanol solution of 70% to 80% by volume at a ratio of 1g:(10 to 15)mL.

[0011] Preferably, the conditions for ultrasonic extraction are: ultrasonic power of 300-500W and ultrasonic extraction time of 15-20min.

[0012] Preferably, the supernatant concentration method includes: vacuum distillation concentration at 45-55°C and a vacuum degree of -0.06 to -0.08 MPa until the relative density is 1.2-1.6.

[0013] Another object of the present invention is to provide a method for preparing the plant-derived insecticide, comprising the following steps: weighing each raw material in proportion; dissolving azadirachtin, croton oil and tallow tree extract in methyl oleate, and then adding agricultural emulsion No. 500, organosilicon surfactants L-77 and EL-90, and emulsifying to obtain the plant-derived insecticide.

[0014] Preferably, the emulsification time is 15–30 min.

[0015] Preferably, the emulsification speed is 7000-8000 rpm.

[0016] Another object of the present invention is to provide the application of the plant-derived insecticide or the preparation method thereof in the control of plant pests.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention provides a plant-derived insecticide that combines plant-derived insecticidal components such as azadirachtin, croton oil, and tallow tree extract with methyl oleate, agricultural emulsion No. 500, and organosilicon surfactants L-77 and EL-90. The combination exhibits a significant synergistic effect and broad-spectrum insecticidal activity. This insecticide is non-toxic to humans and animals, environmentally friendly, and helps improve the quality of agricultural products. Detailed Implementation

[0019] This invention provides a plant-derived insecticide, comprising an active ingredient and adjuvants. The active ingredient, by weight, comprises the following raw materials: 5-10 parts of azadirachtin, 2-4 parts of crotonoleic acid, and 4-8 parts of *Sapium sebiferum* extract. The adjuvants, by weight, comprise the following raw materials: 40-50 parts of methyl oleate, 2-5 parts of agricultural emulsion 500, 5-10 parts of organosilicon surfactant L-77, and 5-10 parts of EL-90. Preferably, azadirachtin comprises 6-8 parts, more preferably 7 parts; crotonoleic acid comprises 3 parts; and *Sapium sebiferum* extract comprises 5-7 parts, more preferably 6 parts. Preferably, methyl oleate comprises 42-48 parts, more preferably 44-46 parts; agricultural emulsion 500 comprises 3-4 parts; organosilicon surfactant L-77 comprises 6-8 parts, more preferably 7 parts; and EL-90 comprises 6-8 parts, more preferably 7 parts. In this invention, the preferred mass ratio of the active ingredient to the adjuvant is 1:(16-24), more preferably 1:(18-22). In this invention, both azadirachtin (purity ≥98%) and crotonoleic acid (purity ≥98%) can be obtained through ordinary commercial channels.

[0020] In this invention, the combination of azadirachtin, crotonoleic acid and Sapium sebiferum extract has a synergistic effect and a significant insecticidal effect. Combining azadirachtin, crotonoleic acid and Sapium sebiferum extract with the adjuvants in this invention can further enhance the killing effect on pests.

[0021] The preferred method for preparing the *Sapium sebiferum* extract of this invention includes: drying and pulverizing fresh *Sapium sebiferum* leaves to obtain *Sapium sebiferum* leaf powder; mixing the *Sapium sebiferum* leaf powder with a 70%–80% (v / v) ethanol solution, ultrasonically extracting, centrifuging the extract to collect the supernatant; concentrating the supernatant and drying it to obtain the *Sapium sebiferum* extract. In a specific embodiment of this invention, the *Sapium sebiferum* leaves are fresh leaves of *Sapium sebiferum*.

[0022] In the preparation method of the *Sapium sebiferum* extract of this invention, fresh *Sapium sebiferum* leaves are preferably dried at 45–55°C, preferably for 5 hours, and then pulverized; preferably pulverized to pass through a 40-mesh sieve; preferably mixed with a 75% (v / v) ethanol solution; preferably mixed with the *Sapium sebiferum* leaf powder at a ratio of 1 g:(10–15) mL, more preferably at a ratio of 1 g:(12–14) mL. The ultrasonic extraction power is preferably 300–500 W, and in some examples may be 300 W, 350 W, 400 W, 450 W, or 500 W; the ultrasonic extraction time is preferably 15–20 min, and in some examples may be 15 min, 16 min, 17 min, 18 min, 19 min, or 20 min. In this invention, the extract is subjected to ultrasonic extraction, with a preferred centrifugation speed of 3000–4000 rpm and a preferred centrifugation time of 10–15 min. After centrifugation, the supernatant is collected, and the residue is preferably subjected to repeated ultrasonic extraction 1–2 times under the same conditions. The combined supernatants are then concentrated. A preferred method for supernatant concentration is vacuum distillation at 45–55°C and a vacuum degree of -0.06–-0.08 MPa until the relative density (at 20°C) is 1.2–1.6. After concentration, the extract is preferably dried at 45–55°C for 1–2 hours to obtain the *Sapium sebiferum* extract. The *Sapium sebiferum* extract obtained by this invention has good insecticidal efficacy. When combined with azadirachtin and crotonic acid, it exhibits a synergistic effect, broadening the insecticidal spectrum and making it suitable for the control of various agricultural pests, thus reducing the use of chemical pesticides.

[0023] This invention also provides a method for preparing the aforementioned plant-derived insecticide, comprising the following steps: weighing each raw material according to a specified ratio; dissolving azadirachtin, croton oil, and tallow tree extract in methyl oleate, then adding agricultural emulsion 500, organosilicon surfactants L-77 and EL-90, and emulsifying to obtain the plant-derived insecticide. The emulsification speed is preferably 7000–8000 rpm, and the emulsification time is preferably 15–30 min.

[0024] The present invention also provides the application of the plant-derived insecticide or the preparation method thereof in the control of plant pests.

[0025] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0026] Example 1

[0027] A plant-derived insecticide, consisting of an active ingredient and adjuvants in a mass ratio of 1:19.

[0028] The active ingredients, by weight, are: 7 parts azadirachtin, 3 parts crotonoleic acid, and 6 parts tallow tree extract.

[0029] The additives, by weight, consist of: 45 parts methyl oleate, 4 parts agricultural emulsion No. 500, 7 parts organosilicon surfactant L-777, and 7 parts EL-907.

[0030] The preparation method of *Sapium sebiferum* extract is as follows: Fresh leaves of *Sapium sebiferum* are dried at 50℃ for 5 hours, pulverized to pass through a 40-mesh sieve, and the powdered leaves are mixed with a 75% ethanol solution at a ratio of 1g:12mL. The mixture is then subjected to ultrasonic extraction at a power of 400W for 16 minutes. After extraction, the mixture is centrifuged at 3500 rpm for 10 minutes, and the supernatant is collected. The residue is extracted once more using the same method, and the supernatants are combined. The combined supernatant is concentrated by vacuum distillation at 50℃ and a vacuum degree of -0.07MPa until the relative density (at 20℃) is 1.5. The mixture is then aerated at 50℃ for 1 hour to obtain the *Sapium sebiferum* extract.

[0031] The preparation method of the plant-derived insecticide is as follows: weigh each raw material according to the proportion; dissolve azadirachtin, croton oil and tallow tree extract in methyl oleate, then add agricultural emulsion No. 500, organosilicon surfactants L-77 and EL-90, and emulsify to obtain the plant-derived insecticide. The emulsification speed is 7000 rpm and the emulsification time is 20 min.

[0032] Example 2

[0033] A plant-derived insecticide, composed of an active ingredient and adjuvants in a mass ratio of 1:24.

[0034] The active ingredients, by weight, are: 6 parts azadirachtin, 3 parts crotonoleic acid, and 7 parts tallow tree extract.

[0035] The additives, by weight, consist of: 48 parts methyl oleate, 2 parts agricultural emulsion No. 500, 575 parts organosilicon surfactant L-7, and 9 parts EL-909.

[0036] The preparation method of the Chinese tallow tree extract is the same as in Example 1, and the preparation method of the plant-derived insecticide is the same as in Example 1.

[0037] Example 3

[0038] A plant-derived insecticide, composed of an active ingredient and adjuvants in a mass ratio of 1:16.

[0039] The active ingredients, by weight, are: 8 parts azadirachtin, 3 parts crotonoleic acid, and 5 parts tallow tree extract.

[0040] The additives, by weight, consist of: 40 parts methyl oleate, 5 parts agricultural emulsion No. 500, 10 parts organosilicon surfactant L-77, and 6 parts EL-906.

[0041] The preparation method of the Chinese tallow tree extract is the same as in Example 1, and the preparation method of the plant-derived insecticide is the same as in Example 1.

[0042] Example 4

[0043] A plant-derived insecticide, consisting of an active ingredient and adjuvants in a mass ratio of 1:19.

[0044] The active ingredients, by weight, are: 5 parts azadirachtin, 4 parts crotonoleic acid, and 8 parts tallow tree extract.

[0045] The adjuvants are the same as in Example 1, the preparation method of the Chinese tallow tree extract is the same as in Example 1, and the preparation method of the plant-derived insecticide is the same as in Example 1.

[0046] Comparative Example 1

[0047] The difference from Example 1 is that the active ingredient does not include tallow tree extract, while the rest is the same as in Example 1.

[0048] Comparative Example 2

[0049] The difference from Example 1 is that the preparation method of the Chinese tallow tree extract is as follows:

[0050] Fresh leaves of *Sapium sebiferum* were dried at 50℃ for 5 hours, then pulverized to pass through a 40-mesh sieve. The powdered leaves were mixed with water at a ratio of 1 g:12 mL and extracted using ultrasound at 400 W for 16 minutes. After extraction, the mixture was centrifuged at 3500 rpm for 10 minutes, and the supernatant was collected. The residue was extracted once more using the same method, and the supernatants were combined. The combined supernatant was concentrated by vacuum distillation at 50℃ and a vacuum of -0.07 MPa until the relative density (at 20℃) was 1.5. The solution was then aerated at 50℃ for 1 hour to obtain the *Sapium sebiferum* extract.

[0051] Comparative Example 3

[0052] The difference from Example 1 is as follows:

[0053] The active ingredients, by weight, are: 7 parts azadirachtin, 6 parts crotonoleic acid, and 3 parts tallow tree extract.

[0054] Comparative Example 4

[0055] The difference from Example 1 is that the additive is methyl oleate.

[0056] Example 5

[0057] Toxicity determination of active ingredients in plant-derived insecticides.

[0058] The active ingredients in Examples 1-4 and Comparative Examples 1-3 were diluted to a series of concentrations using methyl oleate. Fresh, clean mulberry leaves free from pesticide contamination were soaked in each of the diluted solutions for 5 hours, with mulberry leaves soaked in distilled water serving as a control. After drying, the mulberry leaves were placed in petri dishes, and 15 third-instar larvae of the mulberry tussock moth were inoculated into each concentration treatment. Each treatment was repeated three times. After 24 hours of treatment, the mortality rate of the test insects was investigated and recorded.

[0059] The mortality rate formula is: P1 = K / N × 100, where P1 is the mortality rate, K is the number of dead insects, and N is the total number of insects treated.

[0060] The corrected mortality rate formula is: P2=(Pt-P0) / (1-P0)×100, where P2 is the corrected mortality rate, Pt is the treatment mortality rate, and P0 is the blank control mortality rate;

[0061] If the control mortality rate is <5%, no correction is needed. If the control mortality rate is between 5% and 20%, a corrected mortality rate should be calculated. If the control mortality rate is >20%, the experiment needs to be repeated.

[0062] Based on the mortality rate of the test insects, EXCEL software was used, according to the "LC in Bioassays" standard. 50 or LD 50 EXCEL Calculation Methods (Ma Zhenhong, Ma Liangcai. LC in Bioassays) 50 or LD 50 The method described in "Excel calculation methods [J]. Medical Animal Control, 1999, (11): 612-614" is used to calculate LC. 50 .

[0063] The co-toxicity coefficient (CTC value) of the active ingredient in plant-derived insecticides was calculated using Sun Yunpei's method. A CTC value greater than 120 indicates a synergistic effect, a CTC value between 80 and 120 indicates an additive effect, and a CTC value less than 80 indicates an antagonistic effect. The calculation method is as follows:

[0064] Using azadirachtin as the standard single-dose, its toxicity index (TI) is designated as 100. The toxicity index (TI) of other single-dose drugs is equal to the LC of the standard single-dose drug. 50 / LC testing of a single dose 50 ×100;

[0065] Actual Toxicity Index (ATI) of the active ingredient = LC of a standard single-dose formulation 50 LC of the active ingredient 50 ×100;

[0066] Theoretical toxicity index (TTI) of the active ingredient = ∑TI of each individual dose × percentage of each individual dose in the active ingredient;

[0067] The co-toxicity coefficient (CTC) of the active ingredient is calculated as ATI / TTI × 100. The results are shown in Table 1.

[0068] Table 1. Toxicity of active ingredients in plant-derived insecticides to the mulberry tussock moth.

[0069] <![CDATA[LC 50 mg / L]]> Toxicity Index Theoretical toxicity index CTC Sichuan pepper 62.54 100 - - Croton oil 79.82 78.35 - - Sapium sebiferum alcohol extract 46.54 134.38 - - Chinese tallow tree water extract 160.85 38.88 - - Example 1 27.37 228.50 108.83 209.96 Example 2 33.42 187.13 110.98 168.62 Example 3 31.66 197.54 106.68 185.17 Example 4 36.82 169.85 111.08 152.91 Comparative Example 1 68.96 90.69 93.51 96.98 Comparative Example 2 83.18 75.19 73.02 102.97 Comparative Example 3 61.10 102.36 98.33 104.10

[0070] Note: The ethanol extract of Sapium sebiferum was obtained by the method of preparing Sapium sebiferum extract in Example 1; the aqueous extract of Sapium sebiferum was obtained by the method of preparing Sapium sebiferum extract in Comparative Example 2.

[0071] As shown in Table 1, the CTC values ​​of the active ingredients in the plant-derived insecticide provided by this invention are all >120, and the ingredients have a synergistic effect.

[0072] Example 6

[0073] Field efficacy test of plant-derived insecticides.

[0074] 1. The efficacy of plant-derived insecticides against the mulberry tussock moth.

[0075] The target pest is the mulberry tussock moth, and the plant species is the mulberry tree.

[0076] Nine treatments were designed in a mulberry orchard: spraying with water (CK), insecticides from Examples 1-4, and insecticides from Comparative Examples 1-4, with three replicates for each treatment. Spraying was conducted during the peak occurrence period of the mulberry tussock moth. The plant-derived insecticides were diluted 1000 times before spraying. The amount sprayed was sufficient to moisten the leaves without dripping. No other pesticides were sprayed one month prior to the experiment and during the experiment.

[0077] Before applying the pesticide, the initial insect population was investigated. After application, the number of surviving mulberry tussock moths was investigated on days 1, 3, and 7. The insect population reduction rate was used as the control effect. The results are shown in Table 2. The calculation formula is as follows:

[0078] Insect population reduction rate (%) = (Insect population before treatment - Number of surviving insects after treatment) / Insect population before treatment × 100;

[0079] Control effect = (Pest population reduction rate in the treated area - Pest population reduction rate in the control area) / (100 - Pest population reduction rate in the control area) × 100.

[0080] The survey method was a five-point sampling method, with three plants surveyed at each point, for a total of 15 plants surveyed for each treatment.

[0081] Table 2. Control efficacy of plant-derived insecticides against mulberry tussock moth.

[0082]

[0083] 2. The efficacy of plant-derived insecticides against diamondback moth.

[0084] The target pest for control is the diamondback moth, and the crop is cabbage.

[0085] Nine treatments were designed in greenhouses where cabbage was grown: spraying with water (CK), insecticides from Examples 1-4, and insecticides from Comparative Examples 1-4, with three replicates for each treatment. The application rate for each treatment was 5 g / mu (approximately 0.067 hectares) based on the active ingredient content. Application was carried out during the peak period of the diamondback moth outbreak. Before spraying, the plant-derived insecticide was diluted 2000 times. No other pesticides were sprayed in the month prior to and during the experiment.

[0086] Before applying the pesticide, the initial insect population was investigated. After application, the number of surviving diamondback moths was investigated on days 1, 3, and 7. The insect population reduction rate was used as the control effect, and the results are shown in Table 3. The calculation and investigation methods were the same as in "1. Control efficacy of plant-derived insecticides against mulberry tussock moth".

[0087] Table 3. Control efficacy of plant-derived insecticides against diamondback moth.

[0088]

[0089] 3. The efficacy of plant-derived insecticides against leafhoppers.

[0090] The target pest for control is leafhoppers, and the crop is peach trees.

[0091] In a peach orchard infested with leafhoppers, nine treatments were designed: spraying with water (CK), insecticides from Examples 1-4, and insecticides from Comparative Examples 1-4, with three replicates for each treatment. The plant-derived insecticides were diluted 2000 times before spraying. The amount sprayed was sufficient to moisten the leaves without dripping. No other pesticides were sprayed during the month prior to and during the experiment.

[0092] Before applying the pesticide, the initial insect population was investigated. After application, the number of surviving leafhoppers was investigated on days 1, 3, and 7. The insect population reduction rate was used as the control effect, and the results are shown in Table 4. The calculation and investigation methods were the same as in "1. Control efficacy of plant-derived insecticides against mulberry tussock moth".

[0093] Table 4. Efficacy of plant-derived insecticides against leafhoppers

[0094]

[0095] 4. The efficacy of plant-derived insecticides against the yellow-striped flea beetle on leafy greens.

[0096] The target pest for control is the striped flea beetle, and the crop is leafy greens.

[0097] Nine treatments were designed in greenhouses where leafy greens were grown: spraying with water (CK), insecticides from Examples 1-4, and insecticides from Comparative Examples 1-4, with three replicates for each treatment. The application rate for each treatment was 5 g / mu (approximately 0.067 hectares) based on the active ingredient content. Application was carried out during the peak emergence period of adult flea beetles. The plant-derived insecticide was diluted 2000 times before spraying. No other pesticides were applied to any treatment one month prior to the experiment and during the experiment.

[0098] Before applying the pesticide, the initial insect population was investigated. After application, the number of surviving flea beetles was investigated on days 1, 3, and 7. The insect population reduction rate was used as the control effect, and the results are shown in Table 5. The calculation and investigation methods were the same as in "1. Control efficacy of plant-derived insecticides against mulberry tussock moth".

[0099] Table 5. Efficacy of plant-derived insecticides against the yellow-striped flea beetle on leafy greens.

[0100]

[0101] As shown in Tables 2-5, the plant-derived insecticide of this invention can effectively control mulberry tussock moth, diamondback moth, leafhopper, and yellow-striped flea beetle, exhibiting broad-spectrum insecticidal activity. Furthermore, the combination of the plant-derived active ingredient and adjuvants can further enhance the insecticide's control effect on pests.

[0102] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A plant-derived insecticide, characterized in that, It includes active ingredients and adjuvants; the active ingredients, by weight, include the following raw materials: 5-10 parts of azadirachtin, 2-4 parts of croton oleic acid, and 4-8 parts of tallow tree extract; the adjuvants, by weight, include the following raw materials: 40-50 parts of methyl oleate, 2-5 parts of agricultural emulsion 500, 5-10 parts of organosilicon surfactant L-775, and 10 parts of EL-905.

2. The plant-derived insecticide according to claim 1, characterized in that, The mass ratio of active ingredient to excipient is 1:(16-24).

3. The plant-derived insecticide according to claim 1, characterized in that, The preparation method of the Chinese tallow tree extract includes: drying fresh Chinese tallow tree leaves and pulverizing them to obtain Chinese tallow tree leaf powder; mixing the Chinese tallow tree leaf powder with an ethanol solution of 70% to 80% by volume, extracting by ultrasonication, collecting the supernatant by centrifugation of the extract; concentrating the supernatant and drying it to obtain the Chinese tallow tree extract.

4. The plant-derived insecticide according to claim 3, characterized in that, The powdered leaves of Chinese tallow tree were mixed with an ethanol solution of 70%–80% by volume at a ratio of 1g:(10–15)mL.

5. The plant-derived insecticide according to claim 3, characterized in that, The conditions for ultrasonic extraction are: ultrasonic power of 300-500W and ultrasonic extraction time of 15-20min.

6. The plant-derived insecticide according to claim 3, characterized in that, The supernatant concentration method includes: vacuum distillation concentration at 45-55℃ and a vacuum degree of -0.06 to -0.08 MPa until the relative density is 1.2-1.

6.

7. A method for preparing the plant-derived insecticide according to any one of claims 1 to 6, characterized in that, Includes the following steps: Weigh each raw material according to the proportion; dissolve azadirachtin, croton oil and tallow tree extract in methyl oleate, then add agricultural emulsion No. 500, organosilicon surfactants L-77 and EL-90, and emulsify to obtain a plant-derived insecticide.

8. The preparation method according to claim 7, characterized in that, The emulsification time is 15–30 minutes.

9. The preparation method according to claim 7, characterized in that, The emulsification speed is 7000-8000 rpm.

10. The application of the plant-derived insecticide according to any one of claims 1 to 6 or the preparation method according to any one of claims 7 to 9 in the control of plant pests.

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