Preparation of a Silicon-based Nano-chitosan Material and Its Application in Crop Pest Control

Abstract

The present invention discloses the preparation of a silicon-based nano-chitosan material and its application in preventing and controlling crop pests, belonging to the field of nano-pesticides. The application of the silicon-based nano-chitosan material in preventing and controlling crop pests is to prepare the silicon-based nano-chitosan material into a suspension and spray it on crops; the average size of the silicon-based nano-chitosan material is 27.8±4.2 nm, and the zeta potential is 45.3±1.3 mV. It can effectively inhibit the growth of adult aphids on crops and the reproduction of offspring, achieving an efficient pest control effect, and has broad application value in the field of crop pest control.

Description

Technical Field

[0001] The present invention relates to the preparation of a silicon-based nano-chitosan material and its application in controlling crop pests, belonging to the field of nano-pesticides. Background Art

[0002] Broad bean is a globally cultivated leguminous crop because of its nutritious edible seeds. Due to its high protein content, it is widely used as a cheap and high-quality protein source. Aphids are considered the most destructive phytophagous pests in broad bean plants worldwide. They directly feed on the plant phloem and transmit viruses, which may cause serious production losses to crops.

[0003] In the past few decades, chemical insecticides have been the main means of controlling aphids. However, with the extensive and large-scale application of chemical pesticides, their induction of pest resistance, pesticide residues, and adverse effects on the environment and human health have limited their application in pest control.

[0004] Environmentally friendly nanostructured materials are considered a promising green tool for controlling plant diseases and pests. For example, the application of silica in the preparation of insecticides disclosed in Chinese Patent CN101297652A is to apply food antagonist silica in the form of dusting to achieve the effect of controlling crop pests; that is, silica powder falls on the crop surface. When pests crawl, silica will adhere to their body surface, and silica destroys the intersegmental membrane of pests, resulting in the inability of pests to move and forage, and then death.

[0005] Chinese Patent CN113287605A discloses carboxymethyl chitosan-functionalized controlled-release mesoporous silica nanoparticles for controlling Spodoptera frugiperda and its preparation method. Specifically, carboxymethyl chitosan and mesoporous silica are used as functional carriers to load the effective insecticidal ingredient chlorantraniliprole to achieve the effect of controlling Spodoptera frugiperda; among them, the nanoparticles are only used as functional carriers to load insecticides, rather than directly using the nanoparticle materials to achieve the effect of controlling pests. Chinese Patent CN102816349B discloses a chitosan / nano-TiO 2 composite material and its preparation method and application. The chitosan / nano-TiO 2 composite material has a good inhibitory effect on the pathogen of rice bacterial blight; however, pathogens and pests belong to two different types of crop pathogens, and the prior art has not disclosed the inhibitory effect of nano-composite materials, especially chitosan / silicon nano-composite materials, on pests such as aphids. Summary of the Invention

[0006] In response to the above technical problems, the present invention provides a green application of silicon-based nano-chitosan materials in the prevention and control of crop pests. Specifically, silicon-based nano-chitosan materials are used as nano-plant inducers to induce plant natural immune responses to resist pest damage, showing a highly active inhibitory effect on pests, and have broad application value in the field of crop pest control.

[0007] The purpose of the present invention is to provide an application of a silicon-based nano-chitosan material in preventing and controlling crop pests. The application is to prepare the silicon-based nano-chitosan material into a suspension and spray it on plant leaves.

[0008] In one embodiment, the suspension is prepared by dissolving silicon-based nano-chitosan material in water.

[0009] In one embodiment, the concentration of the suspension is 50-200 mg / L; preferably 100 mg / L.

[0010] In one embodiment, the spraying on crops specifically refers to spraying on leaves of crops during the growth period of seedlings.

[0011] In one embodiment, the crops include pea plants, broad bean plants, alfalfa plants, and melilotus plants; preferably broad bean plants, which are also known as southern beans and broad beans, and belong to the Fabaceae family, the genus Vicia, and are annual or biennial herbs.

[0012] In one embodiment, the pest is aphid; preferably pea aphid; pea aphid is an insect of the Aphididae family and the genus Aphis, and its main host plants are leguminous plants, such as pea, broad bean, vetch, alfalfa, and Melilotus oleraceus (herbaceous plant dwelling).

[0013] In one embodiment, the application amount is to spray 10 to 30 mL of a silicon-based nano-chitosan material suspension having a concentration of 100 to 200 mg / L per crop.

[0014] In one embodiment, the average size of the silicon-based nano-chitosan material is 20-40 nm, preferably 27.8±4.2 nm; the zeta potential is 30-50 mV, preferably 45.3±1.3 mV.

[0015] In one embodiment, the preparation of the silicon-based nano-chitosan material comprises the following steps:

[0016] (1) Preparation of mesoporous silica nanomaterials (MSNs)

[0017] Using cetyltrimethylammonium bromide (CTAB) as a template, dissolve it in ultrapure water, adjust the pH value of the solution to 9.0 - 10.0, and heat it to 70 - 80 °C, stir to form an aqueous CTAB solution; at room temperature, dropwise add tetraethyl orthosilicate (TEOS) to the aqueous CTAB solution for reaction, after reaction, age and wash to obtain white MSNs containing the template (CTAB@MSNs), dry in vacuum, calcine, and cool to room temperature to obtain MSNs without the template;

[0018] (2) Preparation of silica-based nanoshell chitosan material (CS-MSNs)

[0019] Dissolve chitosan (CS) in acetic acid and adjust the pH to 5 - 6, stir overnight at room temperature, and then magnetically stir for 36 - 48 hours to obtain a CS solution; add the MSNs prepared in step (1) to the CS solution to form a suspension, centrifuge, wash, and freeze-dry to obtain a silica-based nanoshell chitosan material (CS-MSNs) with mesoporous silica nanoparticles loaded with chitosan.

[0020] In one embodiment, the reaction in step (1) is carried out under stirring at 400 - 800 rpm for 18 - 24 h.

[0021] In one embodiment, the aging in step (1) is carried out at 60 - 80 °C for 24 - 36 h.

[0022] In one embodiment, the calcination temperature in step (1) is 600 - 800 °C for 4 - 8 h.

[0023] In one embodiment, the mass concentration of chitosan in step (2) is 0.5 - 2%; the volume fraction of acetic acid is 2 - 4%.

[0024] In one embodiment, the ratio of MSNs to the CS solution in step (2) is 2 - 8:1, mg / mL; preferably 5:1, mg / mL.

[0025] The second object of the present invention is to provide a method for increasing the Ca 2+ flow rate and salicylic acid content in broad bean leaf cells. The method is to prepare the silica-based nanoshell chitosan material into a suspension and spray it on broad bean leaves. The average size of the silica-based nanoshell chitosan material is 27.8 ± 4.2 nm, and the zeta potential is 45.3 ± 1.3 mV.

[0026] The third object of the present invention is to provide a method for increasing the contents of coumarin and quercetin in broad bean leaves under aphid stress. The method is to prepare a suspension of a silicon-based nanoshell chitosan material and spray it on the plants. The average size of the silicon-based nanoshell chitosan material is 27.8±4.2 nm, and the zeta potential is 45.3±1.3 mV.

[0027] The fourth object of the present invention is to provide a method for controlling broad bean aphids based on inducing an increase in the contents of the insect-resistant substances coumarin and quercetin in broad bean leaves. The method is characterized in that a suspension of a silicon-based nanoshell chitosan material is prepared and sprayed on the leaves of the crop. The average size of the silicon-based nanoshell chitosan material is 27.8±4.2 nm, and the zeta potential is 45.3±1.3 mV.

[0028] The beneficial effects of the present invention are as follows:

[0029] (1) By loading chitosan on mesoporous silica nanoparticles to form a silicon-based nanoshell chitosan composite material, and then using this composite material as a plant immune inducer to activate the systemic acquired resistance of crops to control pests, the present invention can efficiently inhibit the growth of adult aphids on broad beans and the reproduction of their offspring, achieving an efficient pest control effect;

[0030] (2) When the silicon-based nanoshell chitosan material (CS-MSNs) of the present invention is used for controlling crop pests, it can effectively increase the intracellular calcium influx and salicylic acid content in crops. Calcium, as a second messenger, can regulate the immune and stress responses of plants and plays an important role in resisting plant pest stress. Under aphid stress (inoculating aphids), compared with the control group, the CS-MSNs treatment significantly increased the intracellular calcium influx (145.9%), and the promotion effect was significantly higher than the sum of the treatments of spraying CNPs alone (69.3%) and MSNs alone (28.5%). 2+ 2+ Moreover, plant hormones are key signaling molecules mediating the resistance of plants to herbivorous pests. Among them, salicylic acid is mainly involved in regulating the defense response of plants to attacks by piercing-sucking pests such as aphids. When plants are under aphid stress, the CS-MSNs treatment significantly increased the salicylic acid content in broad bean leaves by 343.9%, which was significantly higher than that of the treatment groups of spraying CNPs and MSNs alone. 2+

[0031]

[0032] ​​​(3) When the silicon-based nanoshell chitosan material (CS-MSNs) of the present invention is used for crop pest control, compared with the control group, the CS-MSNs treatment significantly reduces the number of adult aphids (48.3%), and the inhibitory effect is higher than that of the groups treated with CNPs (34.5%) and MSNs (31.0%) alone; especially for the offspring of aphids, the CS-MSNs treatment significantly reduces the number of aphid offspring by 55.1%, and the inhibitory effect is significantly higher than that of the groups treated with CNPs (21.4%) and MSNs (23.5%) alone. Description of the Drawings

[0033] Figure 1 It is the transmission electron microscope characterization diagram of three kinds of nanomaterials prepared in Example 1 of the present invention; (A) is nanoshell chitosan (CNPs); (B) is mesoporous silica nanomaterial (MSNs); (C) is silicon-based nanoshell chitosan material (CS-MSNs);

[0034] Figure 2 It is the Zeta potential and hydrodynamic diameter of three kinds of nanomaterials prepared in Example 1 of the present invention;

[0035] Figure 3 It is the Fourier transform infrared spectrum diagram of MSNs and CS-MSNs nanomaterials prepared in Example 1 of the present invention;

[0036] Figure 4 It is the thermogravimetric analysis diagram of MSNs and CS-MSNs nanomaterials prepared in Example 1 of the present invention;

[0037] Figure 5 It is the data diagram of the control effect of the silicon-based nanoshell chitosan material (CS-MSNs) on broad bean aphids in Example 2 of the present invention; (A) is the number of adult aphids; (B) is the number of aphid larvae;

[0038] Figure 6 It is the data diagram of the influence of the silicon-based nanoshell chitosan material (CS-MSNs) of the present invention on defense signal substances in broad bean leaves inoculated / non-inoculated with aphids; (A) is Ca 2+ Flow rate; (B) is the content of salicylic acid;

[0039] Figure 7 It is the data diagram of the influence of the silicon-based nanoshell chitosan material (CS-MSNs) of the present invention on anti-insect substances in broad bean leaves inoculated with aphids; (A) is coumarin; (B) is quercetin. Detailed Embodiments

[0040] The following further describes the specific embodiments of the present invention in detail in conjunction with the drawings and embodiments.

[0041] Chitosan CS (50 - 190KDa, degree of deacetylation 80%) involved in the embodiments of the present invention; purchased from Sigma - Aldrich Shanghai Trading Co., Ltd.

[0042] Example 1

[0043] 1. Preparation of nano - chitosan CNPs

[0044] Dissolve chitosan CS (0.5% w / v) in 1% (v / v) acetic acid, adjust the pH to 5.2 with 1 mol / L NaOH, and then stir overnight at room temperature to form a CS solution;

[0045] Dissolve tripolyphosphate (TPP: 0.5% w / v) in ultrapure water, and slowly add it to the CS solution (volume ratio 1:3) under magnetic stirring, and continue stirring for 8 hours to form a milky white chitosan nano - suspension; the suspension is centrifuged (4 °C, 12000 rpm, 15 min) with ultrapure water and washed twice, and then freeze - dried to obtain nano - chitosan CNPs.

[0046] 2. Preparation of MSNs

[0047] Using cetyltrimethylammonium bromide (CTAB) as a template, MSNs with a two - dimensional tubular pore structure are prepared; dissolve 2.96 g of cetyltrimethylammonium bromide in 100 mL of ultrapure water, adjust its pH value to 10.0 with ammonium hydroxide; then heat the solution to 80 °C and keep it stirred for 30 minutes to form a CTAB aqueous solution; subsequently, the CTAB aqueous solution is stirred at room temperature until it drops to 30 °C, and 1.86 mL of tetraethyl orthosilicate (TEOS) is added dropwise for reaction. The reaction solution is kept stirred at a speed of 550 rpm for 24 h, and then aged at 80 °C for 24 h; it is centrifuged (8000 rpm, 15 min) and washed 3 times with absolute ethanol, and finally white MSNs containing the template are obtained; finally, the CTAB@MSNs containing CTAB remaining in the nanoparticles are collected and dried under vacuum; then the CTAB@MSNs are calcined at 600 °C for 5 hours and cooled to room temperature to obtain template - free MSNs.

[0048] 3. Preparation of silicon - based nano - chitosan material (CS - MSNs)

[0049] Chitosan CS (0.5% w / v) was dissolved in 2% (v / v) acetic acid, and the pH was adjusted to 5.8 using 1 mol / L NaOH. It was stirred overnight at room temperature and then magnetically stirred at 25 °C for 48 hours to form a CS solution. The prepared dry MSNs (100 mg) were added to the CS solution (20 mL) to form a suspension. Subsequently, the suspension was centrifuged (4 °C, 12,000 rpm, 15 min) and washed 3 times with ultrapure water, and then freeze-dried to obtain CS-MSNs.

[0050] The above-prepared 3 materials were analyzed. The TEM results showed that the average sizes of CNPs, MSNs, and CS-MSNs were 21.2 ± 4.7, 19.5 ± 4.6, and 27.8 ± 4.2 nm ( Figure 1 A–C). The zeta potentials of CNPs, MSNs, and CS-MSNs were 35.2 ± 1.3, -22 ± 0.6, and 45.3 ± 1.3 mV, respectively; their corresponding hydrodynamic diameters were 262.2 ± 8.8, 396.4 ± 17.4, and 598.3 ± 20.4 nm ( Figure 2 ).

[0051] The Fourier transform infrared (FTIR) results showed that, as Figure 3 shown, the presence of the absorption band at 1099.40 cm -1 was attributed to the stretching vibration of the Si-O-Si group, and the peak at 1634.10 cm -1 represented the amino group of CS. CS-MSNs also showed absorption bands at 2918.33 cm -1 and 2846.04 cm -1 , corresponding to the C-H bonds of the methylene and methyl groups of CS, respectively. Thermogravimetric analysis (TGA) showed that the mass contribution of CS to CS-MSNs was 18.3% ( Figure 4 ).

[0052] Example 2

[0053] Application of the silicon-based nanoshell chitosan material (CS-MSNs) in the control of broad bean aphids, including the following steps:

[0054] The method of using greenhouse potted plants was adopted to determine the effect of CS-MSNs in controlling aphids. Specifically: Multiple pots of broad beans were planted, with 500 g of soil (pH 6.8, total organic carbon = 11.3 g / kg, total nitrogen = 1.4 g / kg) in each pot, and one broad bean plant was planted; They were placed in an artificial climate chamber (temperature 25°C, relative humidity 60 ± 5%, light cycle 14 h / 10 h (day / night), effective radiation of light 15000 LX) for cultivation; The pots of broad beans were randomly repositioned twice a week to minimize the position effect; After the broad bean plants grew for two weeks, broad bean seedlings with consistent growth vigor were randomly selected for the following treatments:

[0055] There were a total of 7 groups of treatments, with 4 replicates in each group; The specific grouping was as follows: Control group: Using an equal amount of deionized water as the control;

[0056] CNPs group: 100 mg / L CNPs suspension;

[0057] MSNs group: 100 mg / L MSNs suspension;

[0058] CS-MSNs group: 100 mg / L CS-MSNs suspension;

[0059] CS group: 100 mg / L CS suspension;

[0060] Sodium silicate (SS) group: 100 mg / L SS suspension;

[0061] Traditional insecticide acetamiprid (Ace) group: 100 mg / L Ace suspension;

[0062] A hand-held sprayer was used to spray the leaves of broad beans in each group, and 20 mL of the material suspension was sprayed on each plant; After spraying, 10 third-instar aphids were inoculated into each pot of broad beans. Subsequently, they were covered with a fine mesh bag with a mesh size of 72 μm to prevent aphids from escaping, and they were cultured normally for 7 days.

[0063] Result determination

[0064] 1. Determine the survival numbers of adult and larval aphids on broad beans in each treatment group 7 days after insect inoculation

[0065] The results were as Figure 5 shown. It was found that 7 days after aphid inoculation, large particles of CS and SS had little effect on the growth of aphids. Compared with the control group, the CS-MSNs treatment significantly reduced the number of adult aphids by 48.3%. The inhibitory effect was higher than that of the single spraying of CNPs (34.5%) and MSNs (31.0%) treatment groups, and the effect was also significantly better than that of the traditional insecticide acetamiprid.

[0066] In addition, the CS-MSNs treatment significantly reduced the population of aphid offspring, the nymphs, by 55.1%, which was significantly higher than the single spraying of CNPs (21.4%) and MSNs (23.5%). Figure 5 B), and the inhibitory effect was more prominent compared with the traditional insecticide acetamiprid, which indicated that CS-MSNs could inhibit aphid reproduction more efficiently than CNPs, MSNs and the traditional insecticide acetamiprid.

[0067] 2. Effects of CS-MSNs on signal substances in broad bean leaves

[0068] The Ca content in the mesophyll cells of broad bean under different treatments was measured by non-invasive micro-measurement system (NMT100S-SIM-XY). 2+ A sensor with a tip diameter of 4.5 ± 0.5 μm was used, and a section of filling fluid (Ca) about 1 cm long was injected into it. 2+ :100mM CaCl 2 ), and a LIX reagent (Ca) of about 50 μm in length is drawn from the LIX Holder by the sensor preparation device. 2+ :XY-SJ-Ca-10), chlorinate the silver wire and insert it into the sensor, calibrate it with the corresponding calibration solution, and start the test when the Nernst slope is within the range of 29±3mV; before the test, fix the broad bean seedling leaves in the measurement buffer (0.1mmol / L CaCl 2 , pH 6.0) for 60 minutes for equilibrium; during measurement, ensure that the sensor tip is close to the closest position to the cell surface and maintains a distance of about 1-2 μm from the cell surface, and the step size for each measurement is 20 μm.

[0069] The content of the plant hormone salicylic acid (SA) was determined using LC-MS / MS (Vanquish Flex, Germany).

[0070] 100 mg of broad bean leaves were ground in liquid nitrogen and 1 mL of pre-cooled ethyl acetate (containing 10 μg mL -1 Butylated hydroxytoluene), after vortexing for 15 minutes, the mixture was sonicated in an ice bath for 15 minutes, centrifuged at 4°C, 12000rpm for 10 minutes, the supernatant was transferred to a new centrifuge tube, the supernatant was blown dry with a nitrogen blower, and then reconstituted with 200μL 70% methanol, vortexed for 5 minutes, and continued to be sonicated in an ice bath for 5 minutes, and centrifuged at 4°C, 12000rpm for 10 minutes to collect 100μL of supernatant; finally, the supernatant was injected into the LC-MS / MS system, and the concentration of SA was quantitatively calculated by using the quantitative regression curve of the corresponding standard.

[0071] The results of the test are as followsFigure 6 As shown, under aphid-free stress (without aphid inoculation), compared with the control group, the CS-MSNs treatment significantly increased the Ca 2+ flow rate by 371.8%, with a higher effect than that of the individual spraying of CNPs (234.3%) and MSNs (121.1%) treatments ( Figure 6 A).

[0072] Under aphid stress (with aphid inoculation), compared with the control group, the CS-MSNs treatment significantly increased the Ca 2+ flow rate by 145.9%, with an effect greater than the sum of the individual spraying of CNPs (69.3%) and MSNs (28.5%) treatments ( Figure 6 A). In addition, the CS-MSNs treatment significantly increased the salicylic acid content in broad bean leaves by 256.8% and 343.9% under both aphid-free and aphid stress conditions, which were significantly higher than those of the individual spraying of CNPs and MSNs treatment groups ( Figure 6 B).

[0073] 3. Effects of silicon-based nanochitosan material (CS-MSNs) on anti-insect substances in broad bean leaves

[0074] The relative contents of anti-insect substances in broad bean leaves were determined using LC-MS / MS (Vanquish Flex, Germany). 100 mg of broad bean leaves were ground in liquid nitrogen and transferred to a 2 mL centrifuge tube. 1.5 mL of 80% methanol aqueous solution (containing 0.1% formic acid and 0.2 mg / L 2-chloro-L-phenylalanine as the internal standard) was added. Subsequently, the mixture was vortexed for 1 minute, sonicated in an ice-water bath for 30 minutes, and then centrifuged at 4 °C and 12,000 rpm for 15 minutes to collect the supernatant. The supernatant was freeze-dried and re-dissolved in 200 μL of methanol-acetonitrile-water (4:4:2, v / v / v) solution. Subsequently, 150 μL of the supernatant was collected by centrifugation at 4 °C and 12,000 rpm for 15 minutes. Finally, the supernatant was injected into the LC-MS / MS system for metabolome analysis and quantification. Quality control (QC) samples were prepared using a mixture of all samples in the same amount. For metabolic data, the online tool MetaboAnalyst 5.0 was used. Metabolites with a VIP value >1 and p < 0.05 (inter-group difference) based on PLS-DA analysis were considered differential biomarker metabolites.

[0075] The results are as Figure 7 shown. Under aphid stress, the CS-MSNs treatment significantly increased the coumarin content of leaf anti-insect substances by 273.8%, which was higher than the sum of the individual spraying of CNPs (41.3%) and MSNs (37.7%) treatments ( Figure 7A). In addition, the treatment with CS-MSNs significantly increased the content of quercetin, an anti-insect substance in leaves, by 173.4%, which was also higher than that of the treatments with CNPs (80.6%) and MSNs (118.2%) alone ( Figure 7 B).

[0076] The embodiments provided above are not intended to limit the scope covered by the present invention, nor are the described steps intended to limit the order of their execution. Obvious improvements made by those skilled in the art in combination with the existing well-known general knowledge also fall within the protection scope defined by the claims of the present invention.

Claims

1. Application of silicon-based nano-chitosan material in preventing and controlling crop pests, characterized in that, the application is to formulate silicon-based nano-chitosan into a suspension and spray it on the leaves of plants; the concentration of the silicon-based nano-chitosan material suspension is 50 - 200 mg / L; the average size of the silicon-based nano-chitosan material is 27.8 ± 4.2 nm; zeta potential is 45.3 ± 1.3 mV; the spraying on the leaves of plants specifically refers to spraying on the leaves during the seedling growth period of crops; the pests are aphids; the preparation of the silicon-based nano-chitosan material includes the following steps: (1) Preparation of mesoporous silica nanomaterials MSNs Using cetyltrimethylammonium bromide CTAB as a template, dissolve it in ultrapure water, adjust the pH value of the solution to 9.0 - 10.0, and heat to 70 - 80 °C, stir to form a CTAB aqueous solution; at room temperature, dropwise add tetraethyl orthosilicate to the CTAB aqueous solution for reaction, after reaction, age and wash to obtain white MSNs containing the template, vacuum dry, calcine, and cool to room temperature to obtain template-free MSNs; (2) Preparation of silicon-based nano-chitosan material CS-MSNs Dissolve chitosan CS in acetic acid, adjust the pH to 5 - 6, stir overnight at room temperature, and then magnetically stir for 36 - 48 hours to obtain a CS solution; add the MSNs prepared in step (1) to the CS solution to form a suspension, centrifuge, wash, and freeze-dry to obtain the silicon-based nano-chitosan material CS-MSNs with mesoporous silica loaded with chitosan; the mass concentration of the chitosan is 0.5 - 2%; the volume fraction of acetic acid is 2 - 4%; the ratio of the MSNs to the CS solution is 2 - 8:1, mg / mL.

2. A method for increasing the Ca 2+ flow rate and salicylic acid content in broad bean leaf cells characterized in that, the method is to formulate the silicon-based nano-chitosan material into a suspension and spray it on the leaves of broad beans. The average size of the silicon-based nano-chitosan material is 27.8 ± 4.2 nm, and the zeta potential is 45.3 ± 1.3 mV; the concentration of the silicon-based nano-chitosan material suspension is 50 - 200 mg / L; the preparation of the silicon-based nano-chitosan material includes the following steps: (1) Preparation of mesoporous silica nanomaterials MSNs Using cetyltrimethylammonium bromide CTAB as a template, dissolve it in ultrapure water, adjust the pH value of the solution to 9.0 - 10.0, and heat to 70 - 80 °C, stir to form a CTAB aqueous solution; at room temperature, dropwise add tetraethyl orthosilicate to the CTAB aqueous solution for reaction, after reaction, age and wash to obtain white MSNs containing the template, vacuum dry, calcine, and cool to room temperature to obtain template-free MSNs; (2) Preparation of silicon-based nano-chitosan material CS-MSNs Dissolve chitosan CS in acetic acid, adjust the pH to 5 - 6, stir overnight at room temperature, and then magnetically stir for 36 - 48 hours to obtain a CS solution; add the MSNs prepared in step (1) to the CS solution to form a suspension, centrifuge, wash, and freeze-dry to obtain the silica-based nanocomposite material CS-MSNs with mesoporous silica loaded with chitosan. The mass concentration of the chitosan is 0.5 - 2%; the volume fraction of acetic acid is 2 - 4%; the ratio of the MSNs to the CS solution is 2 - 8:1, mg / mL.

3. A method for increasing the contents of coumarin and quercetin in broad bean leaves under aphid stress Characterized in that the method is to prepare the silica-based nanocomposite material into a suspension and spray it on the plants. The average size of the silica-based nanocomposite material is 27.8 ± 4.2 nm, and the zeta potential is 45.3 ± 1.3 mV. The concentration of the suspension of the silica-based nanocomposite material is 50 - 200 mg / L. The preparation of the silica-based nanocomposite material CS-MSNs includes the following steps: (1)Preparation of mesoporous silica nanoparticles MSNs Using cetyltrimethylammonium bromide CTAB as a template, dissolve it in ultrapure water, adjust the pH value of the solution to 9.0 - 10.0, heat to 70 - 80 °C, and stir to form a CTAB aqueous solution; at room temperature, dropwise add tetraethyl orthosilicate to the CTAB aqueous solution for reaction, age and wash after the reaction to obtain white MSNs containing the template, vacuum dry, calcine, and cool to room temperature to obtain MSNs without the template. (2)Preparation of silica-based nanocomposite material CS-MSNs Dissolve chitosan CS in acetic acid, adjust the pH to 5 - 6, stir overnight at room temperature, and then magnetically stir for 36 - 48 hours to obtain a CS solution; add the MSNs prepared in step (1) to the CS solution to form a suspension, centrifuge, wash, and freeze-dry to obtain the silica-based nanocomposite material CS-MSNs with mesoporous silica loaded with chitosan. The mass concentration of the chitosan is 0.5 - 2%; the volume fraction of acetic acid is 2 - 4%; the ratio of the MSNs to the CS solution is 2 - 8:1, mg / mL.

4. A method for controlling broad bean aphids based on inducing an increase in the contents of the anti-insect substances coumarin and quercetin in broad bean leaves Characterized in that the method is to prepare the silica-based nanocomposite material into a suspension and spray it on the crop leaves. The average size of the silica-based nanocomposite material is 27.8 ± 4.2 nm, and the zeta potential is 45.3 ± 1.3 mV. The concentration of the suspension of the silica-based nanocomposite material is 50 - 200 mg / L. The preparation of the silica-based nanocomposite material includes the following steps: (1)Preparation of mesoporous silica nanoparticles MSNs Using cetyltrimethylammonium bromide (CTAB) as a template, dissolve it in ultrapure water, adjust the pH value of the solution to 9.0 - 10.0, heat it to 70 - 80 °C, and stir to form an aqueous CTAB solution; at room temperature, dropwise add tetraethyl orthosilicate to the aqueous CTAB solution for reaction, and after reaction, age and wash to obtain white MSNs containing the template, dry in vacuum, calcine, and cool to room temperature to obtain MSNs without the template; (2)Preparation of chitosan-based mesoporous silica materials CS-MSNs Dissolve chitosan (CS) in acetic acid, adjust the pH to 5 - 6, stir overnight at room temperature, and then magnetically stir for 36 - 48 hours to obtain a CS solution; add the MSNs prepared in step (1) to the CS solution to form a suspension, centrifuge, wash, and freeze-dry to obtain the chitosan-based mesoporous silica material CS-MSNs with chitosan loaded on mesoporous silica; The mass concentration of the chitosan is 0.5 - 2%; the volume fraction of acetic acid is 2 - 4%; the ratio of the MSNs to the CS solution is 2 - 8:1, mg / mL.

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