Adiantum capillus-veneris extract, and preparation method and use thereof

Abstract

The present application relates to the technical field of pest repellent, and discloses an adiantum reniforme extract, a preparation method and application thereof, wherein the preparation method of the adiantum reniforme extract comprises the following steps: taking adiantum reniforme, extracting by using an organic solvent, and concentrating to obtain the adiantum reniforme extract. It is proved by a large number of experiments that the adiantum reniforme extract has obvious pest antifeeding effect on common agricultural pests such as Pieris rapae, Spodoptera litura, Plutella xylostella and Phyllotreta striolata, and has broad-spectrum insect antifeeding activity.

Description

Technical Field

[0001] This invention relates to the field of insect repellent technology, specifically to an extract of Adiantum capillus-veneris from lotus leaves, its preparation method, and its uses. Background Technology

[0002] Currently, chemical pesticides still dominate the agricultural and forestry pest control system. Long-term application of chemical pesticides not only easily causes environmental pollution and disrupts the natural ecological balance, but also induces significant pesticide resistance in pests, leading to a gradual decline in control effectiveness. Against this backdrop, screening natural products with insecticidal activity from natural resources such as plants, insects, and microorganisms has become the mainstream direction and important approach in pesticide research and development.

[0003] Insect antifeedant activity refers to the many secondary metabolites with defensive functions produced by plants during their coordinated evolution with insects. *Adiantum capillus-veneris* (also known as the lotus-leaved maidenhair fern) Maidenhair nelumboides Belonging to the genus *Adiantum* of the family Adiantaceae, it is the only single-leaved fern in the family distributed in Asia and is also a Class I protected plant in my country. It contains abundant secondary metabolites and has extremely important medicinal value. Traditionally, it is used to treat diseases such as lung heat cough and hepatitis. In the daily maintenance and long-term observation of *Adiantum repens*, it has been found that this species is rarely infected by pests and diseases, and the population does not show obvious symptoms of pest and disease damage. The overall growth is stable and the health is good, showing strong resistance to pests and diseases and environmental adaptability. However, there are currently no reports on the application of *Adiantum repens* extract in insect antifeedant activity. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a lotus leaf maidenhair fern extract, its preparation method, and its uses.

[0005] In a first aspect, the present invention provides a method for preparing an extract of Adiantum capillus-veneris, comprising the following steps: A maidenhair fern extract was obtained by extracting the fern leaves with organic solvents and concentrating the extract.

[0006] In one alternative embodiment, the organic solvent includes at least one of ethanol, petroleum ether, and ethyl acetate.

[0007] In one alternative embodiment, the extraction includes at least one of reflux extraction and liquid-liquid extraction.

[0008] In one optional embodiment, when the organic solvent extraction is a reflux extraction, the organic solvent includes at least one of ethanol, petroleum ether, and ethyl acetate, preferably ethanol; In an optional embodiment, when the organic solvent extraction is a liquid-liquid extraction, the organic solvent includes at least one of ethanol, petroleum ether, and ethyl acetate, preferably petroleum ether and / or ethyl acetate.

[0009] In one optional embodiment, the preparation method includes the following steps: (1) The lotus leaf maidenhair fern was extracted by reflux with ethanol solution to obtain an extract, and the extract was concentrated to obtain an extract paste; (2) Dissolve the extract and perform liquid-liquid extraction. The extraction solvent is petroleum ether and / or ethyl acetate. Concentrate the extract to obtain the extract of Adiantum capillus-veneris. In an optional embodiment, in step (1), the ethanol solution is an 85%-90% (v / v) aqueous ethanol solution; and / or, the reflux extraction includes the following steps: mixing the lotus leaf maidenhair fern and the ethanol solution at a material-to-liquid ratio of 50g:800mL, heating and refluxing for 4-5 times, each reflux extraction time being 2.0-2.5h, and the temperature being 82-85℃, and combining the filtrates; In some alternative implementations, prior to the first reflux extraction, a step of soaking the Adiantum capillus-veneris in an ethanol solution for 10-14 hours is included.

[0010] In some optional embodiments, the volume concentration of the ethanol solution can be any one of 85%, 86%, 87%, 88%, 89%, 90%, or a range between any two values. In some optional implementations, the reflux extraction time is any one of 2.0, 2.1, 2.2, 2.3, 2.4, and 2.5 hours or a range between any two of these values. In some optional embodiments, the reflux extraction temperature can be any one of 82, 82.5, 83, 83.5, 84, 84.5, and 85°C, or a range between any two of these values. And / or, step (2) includes: dissolving the extract in water to obtain an extract solution; adding petroleum ether to the extract solution for liquid-liquid extraction to obtain a first aqueous phase and a petroleum ether phase; then adding ethyl acetate to the first aqueous phase for liquid-liquid extraction to obtain a second aqueous phase and an ethyl acetate phase; finally concentrating the petroleum ether phase and the ethyl acetate phase respectively to obtain a fern extract. In some alternative embodiments, the first aqueous phase and petroleum ether are subjected to liquid-liquid extraction 3-4 times; In some alternative embodiments, the second aqueous phase and ethyl acetate are subjected to liquid-liquid extraction 3-4 times.

[0011] In one optional embodiment, in steps (1) and (2), the concentration is carried out by vacuum concentration using a rotary evaporator at 45-50°C; in some optional embodiments, the concentration temperature can be any one of 45, 46, 47, 48, 49, 50°C or a range between any two of these values. And / or, in step (2), the volume ratio of the aqueous phase to the organic phase is 1:1 each time the liquid-liquid extraction is performed.

[0012] Secondly, the present invention provides a lotus leaf maidenhair fern extract, which is prepared by the preparation method described in the first aspect.

[0013] Thirdly, the present invention provides the use of the lotus leaf maidenhair fern extract prepared by the preparation method described in the first aspect in any of the following: (1) Application in the preparation of pest repellents; (2) Application in the preparation of products for the prevention and control of plant pests.

[0014] In some optional embodiments, the pests or insect pests refer to at least one of the following genera: Lepidoptera (Pieris family, Pieris genus), Lepidoptera (Noctuidae family, Lysimachia genus), Lepidoptera (Pyracantha genus), and Coleoptera (Chrysomelidae family, Flea beetle genus); in one optional embodiment, Lepidoptera (Pieris genus, Pieris family, Pieris genus, including cabbage caterpillar; Lepidoptera (Noctuidae family, Lysimachia genus, including beet armyworm; Lepidoptera (Pyracantha genus, including diamondback moth; Coleoptera (Chrysomelidae family, Flea beetle genus, including yellow-striped flea beetle); And / or, the product for controlling plant pests includes at least one of chemical pesticides, microbial pesticides, plant-derived pesticides, or plant growth regulators; And / or, the plants involved in the prevention and control of plant pests include cruciferous vegetables; the cruciferous vegetables include cabbage, kale, mustard greens or radish.

[0015] Fourthly, the present invention provides an insect repellent, the raw material of which includes extract of Adiantum capillus-veneris from lotus leaves prepared by the preparation method described in the first aspect.

[0016] In one optional embodiment, the target of the pest repellent includes at least one of the following: Lepidoptera: Pieridae genus *Pieroptera*, Lepidoptera: Noctuidae genus *Leptochloa*, Lepidoptera: Pyrethidae genus *Pyrethrum*, Coleoptera: Chrysomelidae family; In another optional embodiment, Lepidoptera: Pieroptera: Pieroptera: Pieroptera: *Pieroptera* genus includes cabbage caterpillar; Lepidoptera: Noctuidae genus *Leptochloa* genus includes beet armyworm; Lepidoptera: Pyrethrum genus *Pyrethrum* genus includes diamondback moth; Coleoptera: Chrysomelidae genus *Flea beetle* genus includes yellow-striped flea beetle. And / or, the method for preparing the pest repellent includes the following steps: dissolving the extract of Adiantum capillus-veneris in a solvent to obtain the repellent; in an optional embodiment, the solvent includes methanol; in an optional embodiment, the concentration of the pest repellent is 0.1-50 mg / mL. And / or, the pest repellent has insect antifeeding activity.

[0017] Fifthly, the present invention also provides a method for preventing and controlling plant pests, comprising applying the lotus leaf maidenhair fern extract prepared by the preparation method described in the first aspect or the pest repellent described in the fourth aspect to the plant; in an optional embodiment, the application method includes root irrigation or spraying the plant.

[0018] The technical solution of this invention has the following advantages: 1. This invention provides a method for preparing an extract of *Adiantum repens*, comprising the following steps: taking *Adiantum repens*, extracting with an organic solvent, concentrating, and obtaining the extract; this extract exhibits insect antifeedant activity. The extract provides a green, low-toxicity natural material for the development of novel plant-derived pesticides, helping to alleviate the residual pollution and resistance problems caused by traditional chemical pesticides; furthermore, the research results expand the application scope of rare plants in the field of biological control, confirming the unique value of *Adiantum repens* in integrated pest management.

[0019] 2. The pest repellent provided by this invention comprises extracts of Adiantum capillus-veneris. Extensive experiments have demonstrated that the pest repellent containing Adiantum capillus-veneris extract exhibits significant antifeedant effects against various common pests, including the cabbage caterpillar (Lepidoptera: Pieridae), the beet armyworm (Lepidoptera: Noctuidae), the diamondback moth (Lepidoptera: Pyrethrum), and the flea beetle (Coleoptera: Chrysophagus). It possesses broad-spectrum insect antifeedant activity. Detailed Implementation

[0020] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0021] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0022] The Adiantum repens used in the following embodiments of the present invention is the Adiantum repens cultivated as described in the patent "CN115500265B A method for rapidly obtaining seedlings from Adiantum repens spores", which was cultivated at the Yangtze River Rare Plant Cultivation Base (Yichang); the applicant promises to release the plant to the public within 20 years from the date of application of this invention.

[0023] Example 1-1 This embodiment provides a method for preparing extracts of Adiantum capillus-veneris, including the following steps: (1) Raw material pretreatment: Take 50g of whole Adiantum capillus-veneris, wash it, dry the surface moisture, grind it into powder and set aside; (2) Extraction: Add 800 mL of 90% (v / v) ethanol aqueous solution to the above-mentioned crushed Adiantum capillus-veneris and soak for 12 h at room temperature. Then perform the first heating and reflux extraction (85℃, 2 h). After the extraction, filter and collect the filtrate. Add 800 mL of 90% ethanol aqueous solution to the filter residue and heat and reflux directly at 85℃ for 2 h. Repeat the extraction 3 times. Combine the filtrates and filter the filtrate with qualitative filter paper. (3) Concentration: The filtered filtrate was concentrated into a paste under reduced pressure at 45°C using a rotary evaporator, yielding 520 mg of paste with a paste yield of 1.04%; (4) Separate extraction: Dissolve the extract in 150 mL of purified water and use an ultrasonic cleaner to promote dissolution until the extract is completely dissolved to obtain an extract solution. Petroleum ether extraction: Separate extraction was performed at a 1:1 volume ratio. First, 150 mL of petroleum ether and 150 mL of extract solution were added to a separatory funnel (specification: 500 mL), the stopper was tightened, and the funnel was inverted 5 times to ensure thorough mixing of the two phases. Then, the mixture was allowed to stand until the petroleum ether phase and the aqueous phase were clearly separated and clear. The aqueous phase and the petroleum ether phase were separated. The above extraction steps were repeated 3 times, and the petroleum ether phases from the 3 extractions were combined, along with the first aqueous phase after repeated extraction and separation. Ethyl acetate extraction: Take 150 mL of ethyl acetate and extract it with the first aqueous phase by separation. Repeat the extraction three times. Combine the ethyl acetate phases from the three extractions and obtain the second aqueous phase after repeated extraction. (5) Concentration: The petroleum ether phase and ethyl acetate phase obtained in step (4) are concentrated under reduced pressure at 45°C using a rotary evaporator to obtain extracts. The quality of the extracts is shown in Table 1.

[0024] Table 1 Extract Quality

[0025] Examples 1-2 This embodiment provides a method for preparing extract of Adiantum capillus-veneris, the steps and parameters of which are the same as in Embodiment 1, except that step (4) is omitted.

[0026] Examples 1-3 This embodiment provides a method for preparing extract of Adiantum capillus-veneris, the steps and parameters of which are the same as in embodiment 1, except that the petroleum ether separation extraction step (4) is omitted. Specifically, the extract is dissolved in 150 mL of pure water and the extract is completely dissolved by using an ultrasonic cleaner to obtain an extract solution. Ethyl acetate extraction: Separate extraction was performed at a 1:1 volume ratio. First, 150 mL of ethyl acetate and 150 mL of extract solution were added to a separatory funnel (specification: 500 mL), the stopper was tightened, and the funnel was turned upside down 5 times to mix the two phases thoroughly. Then, the mixture was allowed to stand until the ethyl acetate phase and the aqueous phase were clearly separated and clear. The aqueous phase and the ethyl acetate phase were separated. The above extraction steps were repeated 3 times, and the ethyl acetate phases from the 3 extractions were combined, as well as the aqueous phase after repeated extraction and separation.

[0027] Examples 1-4 This embodiment provides a method for preparing extracts of Adiantum capillus-veneris, including the following steps: (1) Raw material pretreatment: Take 50g of whole Adiantum capillus-veneris, wash it, dry the surface moisture, grind it into powder and set aside; (2) Extraction: Add 800 mL of 90% (v / v) ethanol aqueous solution to the above-mentioned crushed Adiantum repens and soak at room temperature for 12 h. Then perform the first heating and reflux extraction (82℃, 2.5 h). After the extraction, filter and collect the filtrate. Add 800 mL of 90% (v / v) ethanol aqueous solution to the filter residue and directly heat and reflux at 82℃ for 2.5 h. Repeat the extraction 4 times. Combine the filtrates and filter the filtrate with qualitative filter paper. (3) Concentration: The filtered liquid is concentrated into a paste under reduced pressure using a rotary evaporator at 50°C to obtain the paste; (4) Separate extraction: Dissolve the extract in 150 mL of purified water and use an ultrasonic cleaner to promote dissolution until the extract is completely dissolved to obtain an extract solution. Petroleum ether extraction: Separate extraction was performed at a 1:1 volume ratio. First, 150 mL of petroleum ether and 150 mL of extract solution were added to a separatory funnel (specification: 500 mL), the stopper was tightened, and the funnel was inverted 5 times to ensure thorough mixing of the two phases. Then, the mixture was allowed to stand until the petroleum ether phase and the aqueous phase were clearly separated and distinct. The aqueous phase and the petroleum ether phase were then separated. The above extraction steps were repeated 4 times, and the petroleum ether phases from the 4 extractions were combined, along with the first aqueous phase obtained after repeated extraction and separation. Ethyl acetate extraction: Take 150 mL of ethyl acetate and extract it with the first aqueous phase by separation. Repeat the extraction 4 times. Combine the ethyl acetate phases from the 4 extractions and obtain the second aqueous phase after repeated extraction separation. (5) Concentration: The petroleum ether phase and ethyl acetate phase obtained in step (4) are concentrated under reduced pressure at 50°C using a rotary evaporator to obtain an extract.

[0028] Example 2-1 This embodiment provides a method for preparing an insect repellent, the raw materials of which include the petroleum ether phase extract and ethyl acetate phase extract prepared in Example 1-1, and the method includes the following steps: (1) Dissolve the petroleum ether phase extract and the ethyl acetate phase extract separately in methanol, transfer them to a vial, and dry the methanol with a hair dryer to obtain the two-phase sample powder of Adiantum repens. Seal and store in a refrigerator at 4°C for later use. (2) The above powder is dissolved in methanol to prepare low, medium and high concentration pest repellents as shown in Table 2.

[0029] Table 2 Concentration of Pest Repellents

[0030] Experimental Example 1: Test of insect antifeedant activity of extract from Adiantum capillus-veneris leaf 1. Experimental subjects and host plants Tested pest 1: Cabbage caterpillar ( Pieris rapae The third instar larvae were artificially reared in the laboratory and starved for 24 hours before being tested. (Cabbage White Butterfly) Pieris rapae The cabbage white caterpillar is an insect belonging to the genus Pistil in the family Pistilidae of the order Lepidoptera. It is one of the main pests of cruciferous vegetables. Young larvae feed on the leaf tissue, leaving a transparent epidermis; older larvae bite holes and notches into the leaves, and in severe cases, they can eat all the leaves, leaving only the thick veins and petioles, which prevents the seedlings from forming a head properly, or even kills the entire plant.

[0031] Tested pest 2: Spodoptera litura ( Spodoptera litura The third instar larvae were artificially reared in the laboratory and starved for 24 hours before being tested. (Spodoptera litura) Spodoptera litura (This is a type of insect belonging to the genus Noctuidae in the family Noctuidae of the order Lepidoptera. The larvae have a large appetite and a wide host range, and are common pests on cruciferous vegetables such as Chinese cabbage.)

[0032] Tested pest 3: Diamondback moth ( Plutella xylostella The third instar larvae were artificially reared in the laboratory and starved for 24 hours before being tested. (Prunella vulgaris) Plutella xylostella (This is a type of insect belonging to the genus *Pyracantha* in the family Pyracanthae of the order Lepidoptera. It is a major pest of cruciferous vegetables such as cabbage.)

[0033] Tested pest 4: Yellow-striped flea beetle ( Spodoptera exigua Adult flea beetles were artificially reared in a laboratory and starved for 24 hours before being tested. (Yellow-striped flea beetle) Spodoptera exigua(This is a type of insect belonging to the genus *Flea beetle* in the family Chrysomelidae of the order Coleoptera. The larvae feed on roots, while the adults feed on leaves. It is an important pest of cruciferous crops.)

[0034] Host plant for testing: Routine research and observation have found that the larvae of the above-mentioned pests all like to eat cabbage, and the damage is serious when an outbreak occurs, with a high feeding rate. Therefore, cabbage leaves were selected as the test leaves.

[0035] 2. Testing Methods The leaf disc method was used to study the insect feeding refusal activity. Specifically, small leaf discs treated with pest repellents and blank controls were placed in petri dishes, and then insects that had been starved for 24 hours were placed in them. After a period of time, the feeding area of ​​the insects was determined by measuring the area of ​​the leaf discs, and the feeding refusal rate was calculated.

[0036] Specifically, a 1.2cm diameter hole punch was used to punch holes in the cabbage leaves to obtain round cabbage leaves. The leaves were then placed in petri dishes, with 8 leaves in each petri dish. Low, medium, and high concentrations of petroleum ether-based and ethyl acetate-based pest repellents, as shown in Table 2, were added to round petri dishes containing leaves, completely submerging the leaves for 30 seconds (8 leaves per group), and then air-dried. A blank group was set up, in which the leaves were moistened with methanol for 30 seconds and then air-dried.

[0037] The treated leaves were transferred to plastic petri dishes lined with absorbent filter paper. Eight leaves were placed in each petri dish, and one test pest was placed on each leaf. Holes were drilled in the petri dish lids to ensure that the holes were not large enough for the pests to pass through and were not completely sealed. The petri dishes were placed in a humid environment, and the leaf area was measured at 24h and 48h.

[0038] The formula for calculating the refusal rate is: Refusal rate (%) = (feeding area of ​​the control group - feeding area of ​​the treatment group) / feeding area of ​​the control group × 100%. The total feeding area of ​​8 leaves in each group is substituted into the formula for calculation.

[0039] 3. Test Results (1) Results of the experiment on cabbage caterpillar refusal to eat Petroleum ether phase: Medium and high concentrations of petroleum ether phase extracts of Adiantum capillus-veneris showed significant antifeedant effects on cabbage caterpillars, with the feeding area of ​​the tested pests on the leaf discs being significantly lower than that of the control group; the antifeedant rate of the high concentration treatment group reached 68.96% at 24 hours and 72.02% at 48 hours, as shown in Table 3.

[0040] Table 3. Feed rejection rate of cabbage caterpillars in petroleum ether phase.

[0041] Ethyl acetate phase: Medium and high concentrations of ethyl acetate phase of Adiantum capillus-veneris extract showed significant inhibitory effects on feeding by cabbage caterpillars, while low concentrations showed some inhibition but the effect was weaker; the high concentration treatment group had a 24-hour feeding rejection rate of 57.84% and a 48-hour feeding rejection rate of 60.83%, as shown in Table 4.

[0042] Table 4. Feed rejection rate of the ethyl acetate extract of the cabbage caterpillar

[0043] Conclusion: After extraction with different solvents, the petroleum ether and ethyl acetate phases of the extract from Adiantum repens significantly inhibited the feeding of third-instar larvae of the cabbage caterpillar, and the rejection rate increased significantly with increasing concentration, indicating that these two phases of extract had the strongest insect antifeeding activity.

[0044] (2) Results of the experiment on the antifeeding of the beet armyworm Petroleum ether phase: Medium and high concentrations of petroleum ether phase extracts of Adiantum capillus-veneris showed significant antifeedant effects against Spodoptera litura, with the feeding area of ​​the tested pests on leaf discs being significantly lower than that of the control group; the antifeedant rate in the high concentration treatment group reached 63.27% at 24 hours and 66.93% at 48 hours, as shown in Table 5.

[0045] Table 5. Feed rejection rate of petroleum ether phase for *Spodoptera litura*

[0046] Ethyl acetate phase: Medium and high concentrations of ethyl acetate phase of Adiantum capillus-veneris extract showed significant inhibitory effects on feeding of Spodoptera litura, while low concentrations showed some inhibition but the effect was weaker; the high concentration treatment group had a 24-hour feeding rejection rate of 57.74% and a 48-hour feeding rejection rate of 62.68%, as shown in Table 6.

[0047] Table 6. Feed rejection rate of Spodoptera litura in ethyl acetate phase

[0048] (3) Results of the experiment on diamondback moth's refusal to eat Petroleum ether phase: Medium and high concentrations of petroleum ether phase extracts of Adiantum capillus-veneris showed significant antifeeding effects on diamondback moth, with the feeding area of ​​the tested pests on leaf discs being significantly lower than that of the control group; the antifeeding rate of the high concentration treatment group reached 69.09% at 24 hours and 71.16% at 48 hours, as shown in Table 7.

[0049] Table 7. Feed rejection rate of diamondback moth on petroleum ether phase.

[0050] Ethyl acetate phase: Medium and high concentrations of ethyl acetate phase of Adiantum capillus-veneris extract showed significant inhibitory effects on feeding of Diamondback moth, while low concentrations showed some inhibition but the effect was weaker; the high concentration treatment group had a 24-hour feeding rejection rate of 55.03% and a 48-hour feeding rejection rate of 53.53%, as shown in Table 8.

[0051] Table 8. Feed rejection rate of diamondback moth in ethyl acetate phase.

[0052] (4) Results of the experiment on the refusal to eat by the yellow-striped flea beetle Petroleum ether phase: Medium and high concentrations of petroleum ether phase extracts from Adiantum repens have a significant antifeedant effect on flea beetles. The feeding area of ​​the tested pests on the leaf discs is significantly lower than that of the control group. The antifeedant rate of the high concentration treatment group can reach 62.56% at 24 hours and 58.57% at 48 hours. Specific data are shown in Table 9.

[0053] Table 9. Feed rejection rate of flea beetle in petroleum ether phase.

[0054] Ethyl acetate phase: Medium and high concentrations of ethyl acetate phase of Adiantum repens extract significantly inhibited feeding by Adiantum capillus-veneris. Although low concentrations showed some inhibition, the effect was weak. The high concentration treatment group had a 24-hour feeding rejection rate of 58.72% and a 48-hour feeding rejection rate of 54.01%. Specific data are shown in Table 10.

[0055] Table 10. Food rejection rate of *Aspergillus oryzae* in ethyl acetate phase.

[0056] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing an extract of *Adiantum capillus-veneris*, characterized in that, Includes the following steps: A maidenhair fern extract was obtained by extracting the fern leaves with organic solvents and concentrating the extract.

2. The method for preparing the extract of *Adiantum capillus-veneris* according to claim 1, characterized in that, The organic solvent includes at least one of ethanol, petroleum ether, and ethyl acetate.

3. The method for preparing the extract of *Adiantum repens* according to claim 1 or 2, characterized in that, The organic solvent extraction includes at least one of reflux extraction and liquid-liquid extraction; Optionally, when the organic solvent extraction is a reflux extraction, the organic solvent includes at least one of ethanol, petroleum ether, and ethyl acetate, preferably ethanol; Optionally, when the organic solvent extraction is a liquid-liquid extraction, the organic solvent includes at least one of ethanol, petroleum ether, and ethyl acetate, preferably petroleum ether and / or ethyl acetate.

4. The method for preparing the extract of *Adiantum repens* according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) The lotus leaf maidenhair fern was extracted by reflux with ethanol solution to obtain an extract, and the extract was concentrated to obtain an extract paste; (2) Dissolve the extract and perform liquid-liquid extraction. The extraction solvent is petroleum ether and / or ethyl acetate. Concentrate the extract to obtain the extract of Adiantum capillus-veneris. Optionally, in step (1), the ethanol solution is an 85%-90% (v / v) aqueous ethanol solution; and / or, the reflux extraction includes the following steps: mixing the lotus leaf maidenhair fern and the ethanol solution at a material-to-liquid ratio of 50g:800mL, heating and refluxing for 4-5 times, with each reflux extraction lasting 2.0-2.5h and at a temperature of 82-85℃; Combine the filtrates; Optionally, step (2) includes: dissolving the extract in water to obtain an extract solution; adding petroleum ether to the extract solution for liquid-liquid extraction to obtain a first aqueous phase and a petroleum ether phase; then adding ethyl acetate to the first aqueous phase for liquid-liquid extraction to obtain a second aqueous phase and an ethyl acetate phase; finally concentrating the petroleum ether phase and the ethyl acetate phase to obtain a *Adiantum capillus-veneris* extract. Optionally, in steps (1) and (2), the concentration is carried out by vacuum concentration using a rotary evaporator at 45-50°C; Optionally, in step (2), the volume ratio of the aqueous phase to the organic phase is 1:1 each time the liquid-liquid extraction is performed.

5. A lotus leaf maidenhair fern extract, characterized in that, It is prepared by the preparation method described in any one of claims 1-4.

6. The use of the lotus leaf maidenhair fern extract prepared by the preparation method according to any one of claims 1-4 in any of the following: (1) Application in the preparation of pest repellents; (2) Application in the preparation of products for the prevention and control of plant pests.

7. The application according to claim 6, characterized in that, The pests or insects involved include at least one of the following: Lepidoptera: Pieridae genus *Pieridae*, Lepidoptera: Noctuidae genus *Lycoptera*, Lepidoptera: Pyrethidae genus *Pyrethidae*, Coleoptera: Chrysomelidae genus *Flea Beetle*; Optionally, Lepidoptera: Pieridae genus *Pieridae* includes cabbage caterpillar; Lepidoptera: Noctuidae genus *Lycoptera* includes beet armyworm; Lepidoptera: Pyrethidae genus *Pyrethidae* includes diamondback moth; Coleoptera: Chrysomelidae genus *Flea Beetle* includes yellow-striped flea beetle. And / or, the product for controlling plant pests includes at least one of chemical pesticides, microbial pesticides, plant-derived pesticides, or plant growth regulators; And / or, the plants involved in the prevention and control of plant pests include cruciferous vegetables; optionally, the cruciferous vegetables include cabbage, kale, mustard greens or radish.

8. An insect repellent, characterized in that, The raw materials for the pest repellent include extracts of Adiantum capillus-veneris from lotus leaves prepared by the preparation method described in any one of claims 1-4.

9. The pest repellent according to claim 8, characterized in that, The target insects of the pest repellent include at least one of the following: Lepidoptera (Pieris genus), Lepidoptera (Noctuidae genus), Lepidoptera (Pyracantha genus), Lepidoptera (Pyracantha genus), and Coleoptera (Ceratopteris genus); Optionally, Lepidoptera (Pieris genus) includes cabbage caterpillar; Lepidoptera (Noctuidae genus) includes beet armyworm; Lepidoptera (Pyracantha genus) includes diamondback moth; and Coleoptera (Ceratopteris genus) includes yellow-striped flea beetle. And / or, the method for preparing the pest repellent includes the following steps: dissolving the extract of Adiantum capillus-veneris in a solvent to obtain the repellent; optionally, the solvent includes methanol; optionally, the concentration of the pest repellent is 0.1-50 mg / mL; And / or, the pest repellent has insect antifeeding activity.

10. A method for controlling plant pests, characterized in that, This includes applying the lotus leaf maidenhair fern extract prepared by the preparation method according to any one of claims 1-4 or the pest repellent according to claim 8 or 9 to the plant; optionally, the application method includes root irrigation or spraying the plant.

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