Preparation method and application of matrine nano pesticide

Abstract

The invention discloses a preparation method and application of a sophocarpidine nano-pesticide, dendritic mesoporous silica nanoparticles are ultrasonically dispersed in a methanol solution of sophocarpidine, the mixture is stirred for 45-50 h in a dark place at 10-30 DEG C for a reaction, after the reaction, precipitates are centrifugally collected, washed and freeze-dried, and the sophocarpidine nano-biopesticide is obtained. The sophocarpidine nano biopesticide is prepared by taking dendritic mesoporous silica nanoparticles as a carrier, and dendritic mesoporous silica is of a dendritic mesoporous structure and has the characteristics of larger porosity, uniform particle size, high drug loading rate, slow control effect and the like. The dendritic mesoporous silica has the advantages that the dendritic mesoporous silica can be used for preventing and treating trunk-boring, basal and root-eating pests, the matrine as a biological pesticide can avoid the problems of photolysis and the like after being loaded into the dendritic mesoporous silica, the prevention and treatment effect is improved, the drug resistance of the pests is reduced, the goals of reduction and synergism are achieved, and a new thought is provided for sustainable prevention and treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticide preparations, and in particular to a preparation method of a matrine nanopesticide and application thereof. Background Art

[0002] The longwood borer (Hylurgus ligniperda) and the pine sawyer (Monochamus alternatus) are both important forestry pests, and both are somewhat cryptic. The longwood borer is an important forestry quarantine pest in my country. It can infect newly felled trees, felled stumps, weakened trees, and healthy trees. Both its larvae and adults can bore into the base of the trunk, root collar, and roots to feed, forming tunnels to cause hidden damage. The longwood borer's invasion holes or emergence holes can be seen on the surface of the bark and roots of the affected trees. As an important trunk-boring pest in forestry, the larvae of the pine sawyer bore into the bark, sapwood, and trunk of weakened pine trees, forming irregular tunnels that hinder the transport and transfer of nutrients and water, leading to the weakening and even death of the pine trees.

[0003] Currently, relatively little research has been conducted on the control of the longwood borer in my country. Instead, chemical control, primarily through injection, is used to control pine saw beetles. However, common commercially available stem-injected pesticides are not ideal for adsorption, transfer, penetration, and transmission within tree stems and branches, resulting in poor insecticide efficacy within the tree. Large or repeated applications are often required, increasing control costs while causing toxic effects on the plant. Repeated injections can also cause additional damage. To improve the transport and translocation of pesticides within trees, more innovative formulations are needed.

[0004] Matrine is an environmentally friendly, botanical biopesticide with stomach and contact toxicity, demonstrating excellent control effectiveness against coleopteran pests. However, matrine's chemical structure is susceptible to degradation by environmental factors, resulting in a short shelf life. Therefore, it is imperative to design new pesticide formulations that combine the inherent properties of the pesticide with the ecological characteristics of Monochamus alternatus and the longwood borer to achieve stable, high-drug loading, sustained-release, and efficient transport and penetration. This approach can achieve efficient pesticide utilization and control stem-boring pests, as well as basal and root-boring pests, through non-invasive application methods. Summary of the Invention

[0005] In response to the above-mentioned prior art, the present invention aims to provide a method for preparing a matrine nanopesticide and its application. This invention effectively solves the problems of matrine biopesticides, such as their easy photolysis, poor permeability and transport within trees, low efficacy against hidden pests, and short duration of efficacy.

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

[0007] The first aspect of the present invention provides a method for preparing a matrine nanopesticide, comprising the following steps:

[0008] The dendritic mesoporous silica nanoparticles are ultrasonically dispersed in a methanol solution of matrine, and the mixture is stirred at 10-30°C in the dark for 45-50 hours to react. After the reaction, the precipitate is collected by centrifugation, washed, and freeze-dried to obtain a matrine nanopesticide.

[0009] The dendritic mesoporous silica nanoparticles are prepared by the following method:

[0010] (1) dissolving triethanolamine in water, stirring at 70-90° C. for 25-40 minutes, and then adding cetyltrimethylammonium bromide and sodium salicylate to react with stirring to obtain a reaction system;

[0011] (2) adding tetraethyl orthosilicate to the reaction system in step (1), continuing to stir the reaction, collecting the precipitate after the reaction, washing it, and freeze-drying it to obtain dendritic mesoporous silica nanoparticles.

[0012] Preferably, the concentration of matrine in the methanol solution of matrine is 0.01-100 mg / mL; the ratio of the added amount of the dendritic mesoporous silica nanoparticles to the methanol solution of matrine is 1.0-1000 mg:10-1000 mL.

[0013] Preferably, the stirring time in the dark is 0.1-200 h.

[0014] Preferably, the ratio of the added amounts of water, triethanolamine, cetyltrimethylammonium bromide, sodium salicylate and tetraethyl orthosilicate is 400-600 mL: 1-1.5 mL: 6-9 g: 2-5 g: 60-100 mL.

[0015] Preferably, in step (1), the reaction temperature is 70-90° C., and the reaction time is 50 min-75 min.

[0016] Preferably, in step (2), the reaction temperature is 70-90° C., and the reaction time is 120-140 min.

[0017] Preferably, in step (2), the washing method is:

[0018] The precipitate is first washed with anhydrous ethanol 2-5 times, then washed with a mixed solution of hydrochloric acid and methanol at 50-70° C. 2-5 times, then washed with methanol 2-5 times, and finally washed with deionized water 2-4 times.

[0019] Preferably, in the mixed solution of hydrochloric acid and methanol, the mass fraction of hydrochloric acid is 36-38%, and the volume ratio of hydrochloric acid to methanol is (25-35):(300-2500).

[0020] Preferably, the particle size of the dendritic mesoporous silica nanoparticles is 100-400 nm.

[0021] The second aspect of the present invention provides a matrine nanopesticide prepared using the above preparation method.

[0022] The third aspect of the present invention provides the use of the above-mentioned matrine nanopesticide in any one of the following (1)-(4):

[0023] (1) Improve the penetration of matrine into bark;

[0024] (2) Increase the transmission speed of matrine in the tree trunk.

[0025] (3) Control of stem-boring pests;

[0026] (4) Prevent and control pests that eat the base and roots.

[0027] Preferably, the trunk-boring pests are of the family Cerambycidae, the family Cariculidae or the family Curculionidae; and the base-boring and root-boring pests are of the family Barktiidae, the family Grubs, the family Molecrickets or the family Wireworms.

[0028] A fourth aspect of the present invention provides a method for controlling stem-boring pests by non-injurious application of pesticides, comprising the following steps:

[0029] (1) dispersing the above-mentioned matrine nanopesticide into an aqueous solution of a penetration enhancer and stirring uniformly to obtain a matrine nanopesticide composite preparation;

[0030] (2) Spray or apply the matrine nano-biopesticide compound preparation directly to the base of the tree trunk near the ground, the stem or the branches and leaves.

[0031] Preferably, the ratio of the added amount of matrine nanopesticide and the penetration enhancer is (80-120) mg: (20-30) mL.

[0032] Preferably, the aqueous solution of the penetration enhancer is prepared by the following method:

[0033] Polyether-modified heptamethyltrisiloxane and apple essential oil were added dropwise into water and stirred evenly to obtain an aqueous solution of a penetration enhancer.

[0034] Preferably, the ratio of water, polyether-modified heptamethyltrisiloxane and apple essential oil added is (20-30) mL: (15-25) μL: (5-15) μL.

[0035] Beneficial effects of the present invention:

[0036] (1) The present invention uses dendritic mesoporous silica nanoparticles as a carrier to prepare matrine nano-biopesticide. The dendritic mesoporous silica is a dendritic mesoporous structure with the characteristics of greater porosity, uniform particle size, high drug loading rate, slow control effect, etc. The matrine nano-biopesticide prepared by the present invention has a high drug loading rate and can be used to prevent and control various pests that bore into the trunk, base and root systems. Matrine, as a bio-source pesticide, can avoid problems such as photolysis after being loaded into the dendritic mesoporous silica, and improves the prevention and control effect, reduces the drug resistance of pests, and achieves the goal of reducing the amount and increasing the efficiency, providing a new idea for sustainable prevention and control.

[0037] (2) The matrine nano-biopesticide compound preparation prepared by the present invention in combination with silicone surfactants and plant essential oils has the characteristics of high penetration transmission, high wetting and spreading, high adhesion and diffusion, and is eco-friendly, and is suitable for the use environment of protecting trees with different morphological characteristics.

[0038] (3) The present invention uses a non-invasive spraying method to directly spray or apply high concentrations to the base, stem, branches and leaves near the ground of the tree trunk, without the need for drilling and injection of medicine, and is suitable for a variety of application scenarios.

[0039] (4) The present invention combines matrine raw material, a permeation enhancer and dendritic mesoporous silica nanoparticles to study their effects on matrine penetration through the bark and the transmission speed within the trunk. The results show that the use of matrine and permeation enhancer alone or matrine and dendritic mesoporous silica nanoparticles can improve the penetration of matrine through the bark and the transmission speed within the trunk. However, when the three are used in combination, the transmission speed of matrine within the trunk is significantly improved, indicating that the permeation enhancer and dendritic mesoporous silica nanoparticles have a significant synergistic effect on improving the penetration of matrine through the bark and the transmission speed within the trunk. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 : Electron microscope morphology of the dendritic mesoporous silica prepared in Example 1.

[0041] Figure 2 : X-ray diffraction patterns of dendritic mesoporous silica and matrine nanopesticide prepared in Example 1.

[0042] Figure 3 : Slow release curves of matrine nanopesticide under different pH conditions.

[0043] Figure 4 :Transmission effect of isothiocyanate-labeled matrine nano-biopesticide compound preparation in pine bark and roots.

[0044] Figure 5:Distribution of isothiocyanate-labeled matrine nanopesticide compound preparation on the surface and body of Monochamus alternatus larvae and Oryctolagus longissima adults. DETAILED DESCRIPTION

[0045] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0046] As described in the background art, the longwood borer is a major invasive species in forestry, having been introduced to my country in recent years, where it bores beneath the bark and causes damage. The pine alternatus, on the other hand, is a major trunk-boring pest in forestry. Its larvae bore into healthy pine trees, and the adults spread pine wilt disease when feeding on tender branches to supplement their nutrition. Both pests are somewhat hidden from view during their larval stages, and existing conventional control methods, such as punching and injection, and aerial spraying, all have certain limitations. Directly applying pesticides from the outside makes it difficult for pesticides to penetrate the bark and reach the interior of the tree and the target pests, resulting in unsatisfactory control effects. Furthermore, punching and injection also cause additional damage to the tree, exacerbating the risk of infection by other harmful organisms. Furthermore, although many common pesticides on the market have good plant absorption properties, their adhesion, wettability, and permeability on the plant surface are unsatisfactory. When sprayed, most of the active ingredients are lost to the environment, leaving very little that ultimately affects the target organisms, resulting in extremely low pesticide utilization.

[0047] Based on this, the present invention provides a preparation method and application of matrine nanopesticide, adopts a method of non-damage application of pesticides to control trunk-boring pests, physically adsorbs matrine through nano-carrier dendritic mesoporous silica to prepare a high-drug-loaded matrine nano-biopesticide, and uses it in combination with silicone and plant essential oils, which greatly improves the transportation efficiency of nanopesticides penetrating the bark into the xylem and pith of trees, providing a new material and platform for the prevention and control of boring pests.

[0048] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific embodiments.

[0049] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0050] The apple essential oil used in the present invention was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0051] The 0.3% matrine aqueous solution used in the present invention was purchased from Beijing Qingyuanbao Biotechnology Co., Ltd.

[0052] The 95% matrine technical used in the present invention was purchased from Beijing Qingyuanbao Biotechnology Co., Ltd.

[0053] Example 1: Preparation of matrine nanopesticide:

[0054] (1) Add 1.2 mL of triethanolamine to 500 mL of water, place in an 80°C oil bath, and stir with a mechanical stirrer for 30 min to obtain a triethanolamine solution;

[0055] (2) adding 7.6 g of hexadecyltrimethylammonium bromide and 3.3 g of sodium salicylate to the triethanolamine solution prepared in step (1), and continuing to stir and react at 80° C. for 1 h to obtain a reaction system;

[0056] (3) 80 mL of tetraethyl orthosilicate was added to the reaction system prepared in step (2), and the reaction was continued at 80° C. with stirring for 2 h. After the reaction, the mixture was centrifuged at 11,000 rpm for 30 min to collect the white precipitate, which was then washed three times with anhydrous ethanol to remove unreacted substances.

[0057] (4) Add 300 mL of methanol to the precipitate obtained in step (3), ultrasonically disperse the precipitate, then add 30 mL of 37 wt% concentrated hydrochloric acid, heat in a 60°C water bath, and magnetically stir for 6 h to remove the template. Centrifuge at 11,000 rpm for 30 min to collect the precipitate, and repeat the above steps three times;

[0058] (5) The precipitate obtained in step (4) was washed with 300 mL of methanol to remove excess hydrochloric acid, washed three times, and the precipitate was washed with deionized water three times. The precipitate was added with 20 mL of deionized water and placed in a -20°C freezer for 24 h, and then freeze-dried at -56°C for 48 h to obtain a white powder which was dendritic mesoporous silica nanoparticles. The yield of the obtained dendritic mesoporous silica was 90.0%, and the particle size of the dendritic mesoporous silica nanoparticles was about 250 nm.

[0059] (6) Dissolve 200 mg of matrine in 25 mL of methanol to prepare a methanol solution of matrine;

[0060] (7) Weigh 10 mg of the dendritic mesoporous silica powder obtained in step (5) and add it to 25 mL of the matrine methanol solution prepared in step (6). Stir magnetically in the dark for 48 h. After the reaction, collect the precipitate by centrifugation, wash the precipitate with deionized water, and freeze-dry at -56°C for 48 h to obtain the matrine nanopesticide. The drug loading of the prepared matrine nanopesticide is 80%.

[0061] Figure 1This is an electron microscope morphology of the dendritic mesoporous silica prepared in Example 1. From the left image, it can be seen that the size of the dendritic mesoporous silica nanoparticles is uniform, with a particle size of about 200 nm. From the magnified unit on the right image, it can be seen that the dendritic pores of the silica nanoparticles are large and uneven, and the sufficient specific surface area provides a basis for drug loading.

[0062] Figure 2 The dendritic mesoporous silica (DMSN) prepared in Example 1 S ) and matrine nanopesticide (MAT@DMSN S ) X-ray diffraction pattern, from which it can be seen that dendritic mesoporous silica belongs to amorphous silicon, and its amorphous structure is not affected before and after drug loading.

[0063] Example 2: Preparation of matrine nanopesticide compound preparation:

[0064] (1) Preparation of penetration enhancer:

[0065] 20 μL of polyether-modified heptamethyltrisiloxane and 10 μL of apple essential oil were added dropwise to 25 mL of deionized water, and the system was mixed evenly under magnetic stirring for 30 min to obtain a penetration enhancer.

[0066] (2) 100 mg of the matrine nanopesticide prepared in Example 1 was dispersed in 500 mL of the permeation enhancer prepared in step (1), and magnetic stirring was performed for 30 min to obtain a matrine nanopesticide composite preparation.

[0067] Test Example 1: Indoor toxicity determination of different matrine agents against Monochamus alternatus and Trichoderma longituba:

[0068] 1. Test method:

[0069] (1) Preparation of test agents: Commercially available 0.3% matrine aqueous solution, 95% matrine technical and the matrine nanopesticide prepared in Example 1 were prepared into different concentrations.

[0070] (2) Pretreatment of test insects: Select 3-day-old larvae of Monochamus truncatus with uniform size and good growth and development, and starve them for 24 h; select adults of Microhylidae spp. with uniform size and good growth and development, and starve them for 24 h.

[0071] (3) Contact toxicity test: The larvae of Monochamus alternatus were completely immersed in the test agent for 15 seconds, then taken out and placed on filter paper to remove excess solution.

[0072] (4) Gastric poison test treatment:

[0073] Monochamus alternatus: put 3g of fresh artificial feed for Monochamus alternatus larvae into the feed box, add 1mL of matrine nano-biopesticide solution of different concentrations and stir evenly, and put the third-instar pine larvae into it.

[0074] Long forest borer: Take the phloem of black pine and place it in different concentrations of pesticides and soak it evenly for 30 seconds. After taking it out, use absorbent paper to absorb the excess pesticide on the phloem. The adult long forest borer will feed on and bore into the phloem of black pine.

[0075] (5) Experimental and control groups: In steps (3) and (4), 10 test insects constituted one replicate group, and 3 replicates were set for each concentration treatment. Clean water was used as a blank control group.

[0076] (6) The test insects were placed in a constant temperature incubator at 25 ± 1 ° C and relative humidity (RH) of 65 ± 10% in the dark. After 96 hours of treatment, the insects were repeatedly touched with tweezers. Those without reaction were considered dead, and those without reaction were considered alive. The number of live and dead insects was recorded, and the mortality rate and LC were calculated. 50 value.

[0077] 2. Experimental results:

[0078] Table 1 Contact toxicity of different matrine reagents to Monochamus alternatus

[0079]

[0080] As shown in Table 1, the LC values ​​of matrine nanopesticide on Monochamus alternatus larvae at 96 h were 50 The value is 31.12μg / mL, and the LC of 0.3% matrine aqueous solution is 50 The value is 62.76μg / mL, and the LC of matrine technical is 50 It is 58.20μg / mL, and the contact toxicity to the larvae of pine sawyer beetles is: matrine nano-biopesticide > matrine technical > 0.3% matrine aqueous solution.

[0081] Table 2 Toxicity of different matrine reagents to Monochamus alternatus in the stomach

[0082]

[0083] As shown in Table 2, the LC50 value of matrine nanopesticide to pine sawyer beetle larvae at 96 h was 27.55 μg / mL, the LC50 value of 0.3% matrine aqueous solution was 57.76 μg / mL, and the LC50 of matrine technical was 35.00 μg / mL. The stomach toxicity to pine sawyer beetle larvae was: matrine nanopesticide > matrine technical > 0.3% matrine aqueous solution.

[0084] Table 3 Stomach toxicity of different matrine reagents to the long forest beetle

[0085]

[0086] As shown in Table 3, the LC50 value of matrine nanopesticide to adults of the long forest beetle in 96 hours was 28.0 μg / mL, the LC50 value of 0.3% matrine aqueous solution was 60.6 μg / mL, and the LC50 of matrine technical was 37.3 μg / mL. The stomach toxicity to the long forest beetle was matrine nanopesticide > matrine technical > 0.3% matrine aqueous solution.

[0087] Test Example 2: Release of matrine nanopesticide under different pH conditions:

[0088] Weigh 80mg of the matrine nanopesticide prepared in Example 1 and evenly disperse it in PBS buffer solutions of different pH values ​​(6.5, 7.4, and 8.2). Subsequently, the above solution was always placed in a 25°C constant temperature, light-free shaking table. 4mL of the sample was taken at different time periods for centrifugation to collect the precipitate. The precipitate was washed with methanol to dissolve the released matrine in methanol and centrifuged to obtain a supernatant. The absorbance of each supernatant was measured at a wavelength of 220nm using an ultraviolet spectrophotometer. The release amount was calculated according to the matrine standard curve equation, and a release curve was drawn.

[0089] Experimental results: Figure 3 The slow release curve of matrine nanopesticide under different pH conditions is shown in Figure 2. Figure 3 The release rate of matrine nanopesticide was relatively stable under acidic (pH 6.0), neutral (pH 7.4), and alkaline (pH 8.2) conditions, with no sudden release. Furthermore, matrine nanopesticide showed the best release effect under alkaline conditions, followed by neutral conditions. The highest cumulative release rate of matrine under alkaline conditions reached 60% over 700 hours, indicating that matrine nanopesticide has good sustained-release properties.

[0090] Test Example 3: Biodistribution of the isothiocyanate-labeled matrine nanopesticide compound formulation inside pine trees, on Monochamus alternatus and on the bodies of Trichoderma longituba:

[0091] 1. Test method:

[0092] 1.1 Preparation of Isothiocyanate-labeled Matrine Nanopesticide Compound Preparation:

[0093] (1) Weigh 20 mg of fluorescein isothiocyanate and dissolve it in 100 mL of deionized water. Ultrasonicate the solution to obtain a fluorescein isothiocyanate aqueous solution.

[0094] (2) Add 25 mg of the matrine nanopesticide prepared in Example 1 to the isothiocyanate fluorescent aqueous solution prepared in step (1), disperse evenly by ultrasonication, and stir magnetically in the dark at room temperature for 8 h;

[0095] (3) The system obtained in step (2) was placed at 11000 rpm and centrifuged for 30 min to collect the precipitate;

[0096] (4) washing the precipitate obtained in step (3) with deionized water three times to remove unadsorbed fluorescein isothiocyanate, and freeze-drying the purified precipitate in the dark to obtain a powder, which is the isothiocyanate-labeled matrine nanopesticide;

[0097] (5) A penetration enhancer was prepared according to the method of the penetration enhancer in step (1) of Example 2. 20 mg of isothiocyanate-labeled dendritic mesoporous silica nanoparticles was added to 100 mL of the penetration enhancer and stirred for 30 min to fully mix to obtain an isothiocyanate-labeled matrine nanopesticide compound preparation.

[0098] 1.2 Distribution test of isothiocyanate-labeled matrine nanopesticide compound formulation inside pine trees:

[0099] The isothiocyanate-labeled matrine nano-biopesticide compound preparation was sprayed on the bark surface of the black pine trunk near the ground. After being protected from light for a period of time, the trunk sections, bark and roots were cut off, and the fluorescence distribution of the cross-section and longitudinal section of the trunk sections, the inside and outside of the bark, the outside of the roots and the longitudinal section of the roots was observed using a small animal live imaging device.

[0100] 1.3 Biodistribution test of isothiocyanate-labeled matrine nanopesticide compound formulation in Monochamus alternatus and Trichoderma longituba:

[0101] 1.3.1 Disperse 10 mg of isothiocyanate-labeled matrine nanopesticide compound preparation in 100 mL of deionized water and spray it on the body surface of Monochamus alternatus larvae and adults of L. longituba. After 1 minute, rinse the insect surface with a slow stream of water to remove the isothiocyanate-labeled matrine nanopesticide compound preparation that has not entered or adhered to the insect body wall, and observe the fluorescence distribution using an inverted fluorescence microscope.

[0102] 10 mg of an isothiocyanate-labeled matrine nanopesticide formulation was dispersed in 1 mL of deionized water and mixed evenly with 1 g of fresh artificial feed for Monochamus alternatus larvae. The mixture was then fed to Monochamus alternatus larvae. Three hours later, the larvae were dissected. The distribution of fluorescence in the larvae and their intestines was observed using an inverted fluorescence microscope.

[0103] 2. Test results:

[0104] Figure 4From left to right and from top to bottom are the fluorescence distribution images of the wood section cross section, longitudinal section, outer surface of bark, inner surface of bark, outer surface of root and longitudinal section of root. It can be seen that the fluorescence distribution is uniform and bright, which shows that the isothiocyanate-labeled matrine nano-biopesticide compound preparation can penetrate from the outer surface of the bark to the inside and be transported longitudinally. It has good penetration and transportation capabilities. The combination of the penetration enhancer helps the isothiocyanate-labeled matrine nano-biopesticide compound preparation to enter and be transported in the tree body.

[0105] Figure 5 From left to right, images of fluorescence distribution are shown on the body wall and internal tissues of Monochamus alternatus larvae and the dorsal and ventral surfaces of adult Trichoderma longifolia beetles. Fluorescence distribution on the body walls of both Monochamus alternatus and Trichoderma longifolia indicates good adhesion of the isothiocyanate-labeled matrine nanopesticide combination to the insects' body walls. Significant fluorescence is also observed in the internal tissues of Monochamus alternatus, indicating that the isothiocyanate-labeled matrine nanopesticide combination can enter the bodies of Monochamus alternatus larvae after feeding.

[0106] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing matrine nanopesticide, characterized in that: The following steps are involved: The dendritic mesoporous silica nanoparticles are ultrasonically dispersed in a methanol solution of matrine, and the mixture is stirred at 10-30°C in the dark for 45-50 hours to react. After the reaction, the precipitate is collected by centrifugation, washed, and freeze-dried to obtain a matrine nanopesticide. The dendritic mesoporous silica nanoparticles are prepared by the following method: (1) dissolving triethanolamine in water, stirring at 70-90° C. for 25-40 minutes, and then adding cetyltrimethylammonium bromide and sodium salicylate to react with stirring to obtain a reaction system; (2) adding tetraethyl orthosilicate to the reaction system in step (1), continuing to stir the reaction, collecting the precipitate after the reaction, washing it, and freeze-drying it to obtain dendritic mesoporous silica nanoparticles.

2. The preparation method according to claim 1, characterized in that The concentration of matrine in the methanol solution of matrine is 0.01-100 mg / mL; the ratio of the added amount of the dendritic mesoporous silica nanoparticles to the methanol solution of matrine is 1.0-1000 mg:10-1000 mL.

3. The preparation method according to claim 1, characterized in that The ratio of the added amounts of water, triethanolamine, hexadecyltrimethylammonium bromide, sodium salicylate and tetraethyl orthosilicate is 400-600 mL: 1-1.5 mL: 6-9 g: 2-5 g: 60-100 mL.

4. A matrine nanopesticide prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the matrine nanopesticide according to claim 5 in any one of the following (1) to (4): (1) Improve the penetration of matrine into bark; (2) Increase the transmission speed of matrine in the tree trunk. (3) Control of stem-boring pests; (4) Prevent and control pests that eat the base and roots.

6. The use according to claim 5, characterized in that The trunk-boring pests are of the family Cerambycidae, the family Cariculidae or the family Curculionidae; the base-boring and root-boring pests are of the family Barkbaridae, the family Grubs, the family Mole Crickets or the family Wireworms.

7. A method for controlling trunk-boring pests by applying pesticides without causing any damage, characterized in that: The following steps are involved: (1) dispersing the matrine nanopesticide according to claim 4 into an aqueous solution of a penetration enhancer and stirring the mixture to obtain a matrine nanopesticide composite preparation; (2) Spray or apply the matrine nano-biopesticide compound preparation directly to the base of the tree trunk near the ground, the stem or the branches and leaves.

8. The method according to claim 7, characterized in that The ratio of the added amount of matrine nanopesticide and the penetration enhancer is (80-120) mg: (20-30) mL.

9. The method according to claim 7, characterized in that The aqueous solution of the penetration enhancer is prepared by the following method: Polyether-modified heptamethyltrisiloxane and apple essential oil were added dropwise into water and stirred evenly to obtain an aqueous solution of a penetration enhancer.

10. The method according to claim 9, characterized in that The ratio of water, polyether-modified heptamethyltrisiloxane and apple essential oil added is (20-30) mL: (15-25) μL: (5-15) μL.

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