A method for controlling Plutella xylostella based on a reduction-responsive nanonicotinoid pesticide

Abstract

The present invention discloses a method for controlling Plutella xylostella based on a reduction-responsive nano-acetamiprid pesticide, belonging to the field of nano-pesticides. First, a mesoporous silica nano-carrier and didodecyl disulfide are prepared. Then, the mesoporous silica nano-carrier is modified with a thiol group, and the thiol group-modified mesoporous silica nano-carrier is blocked with didodecyl disulfide. Finally, it is compounded with acetamiprid to prepare a reduction-responsive nano-acetamiprid pesticide. The reduction-responsive nano-acetamiprid pesticide adopted by the present invention has good pH, temperature, light and long-term storage stability, and has broad application value in the field of controlling Plutella xylostella in farmland; moreover, the method for using the reduction-responsive nano-acetamiprid pesticide to control Plutella xylostella is simple and has strong versatility, without the need for special equipment.

Description

Technical Field

[0001] The present invention relates to a method for controlling diamondback moths based on a reduction-responsive nano-acetamiprid pesticide, belonging to the field of nano-pesticides. Background Art

[0002] In modern agriculture, the use of pesticides has played a substantial role in ensuring global food production. However, traditional pesticide formulations have problems such as low utilization rate and large dosage, which have caused a series of adverse effects on agricultural product safety, human health, and the ecological environment. Therefore, the development of safe and environmentally friendly green nano-pesticide formulations is of great significance for ensuring agricultural product safety, reducing environmental pollution, etc., and shows good application prospects in promoting the reduction of pesticide application and increasing efficiency, and promoting the sustainable development of the pesticide industry.

[0003] In recent years, there have been stimulus-responsive pesticide delivery systems with properties such as pH, enzyme, light, and reduction sensitivity. Glutathione (GSH) is an important reducing substance in plant cells. Usually, the concentration of GSH outside the cell is about 2 μM, and after plant tissues are subjected to biotic and abiotic stresses, its GSH concentration will increase rapidly. Since disulfide bonds are prone to breakage under the action of high-concentration GSH, this also creates the possibility for the application of reduction-sensitive delivery systems in crop pest control. At the same time, encapsulating pesticide active ingredients in a nano-delivery system can also improve the stability information of the active ingredient of the pesticide, avoiding the interference of external environmental factors (temperature, light, pH, etc.) and resulting in the loss of the activity of the active ingredient of the pesticide, which is beneficial to the storage and transportation of pesticides. Therefore, reduction-responsive nano-pesticides have great application potential in the controlled release of drugs and the control of agricultural pests and diseases.

[0004] Currently, there are already some nano-pesticides that respond to pH, enzyme, light, and reduction sensitivity. Although constructing nano-pesticides with these different environmentally responsive nano-carriers has many advantages, there are still various defects in the physicochemical and biological properties of the nano-carriers, selectivity between normal and diseased sites, and stability in various environments. For example, the pH values between normal and diseased sites are close, which may cause pesticides to be released from pH-responsive carriers to non-target sites. The small temperature difference between different parts of plants may cause premature disintegration of temperature-responsive carriers. Although enzymes have good specificity, different stages of pest infestation may be accompanied by different expression levels of target enzyme activity, resulting in insufficient or untimely release of pesticides from enzyme-responsive carriers. Therefore, the redox-responsive release system has become an ideal nano-pesticide construction system, which can quickly respond to the accumulation of redox substances caused by plant pests. Summary of the Invention

[0005] [Technical Problem]

[0006] Currently, existing nano-pesticides responsive to pH, enzymes, light, reduction, etc. still have various defects in terms of physicochemical and biological properties, selectivity between normal and diseased sites, stability in various environments, etc.

[0007] [Technical Solution]

[0008] To solve the above problems, the present invention first prepares a mesoporous silica nano-carrier and didodecyl disulfide, then modifies the mesoporous silica nano-carrier with a thiol group, and then uses didodecyl disulfide to block the thiol-modified mesoporous silica nano-carrier. Finally, it is compounded with acetamiprid to prepare a reduction-responsive nano-acetamiprid pesticide. The reduction-responsive nano-acetamiprid pesticide adopted by the present invention has good pH, temperature, light, and long-term storage stability, and has broad application value in the field of controlling Plutella xylostella in farmland; moreover, the method of using the reduction-responsive nano-acetamiprid pesticide for controlling Plutella xylostella is simple, has strong versatility, and does not require special equipment.

[0009] The first object of the present invention is to provide a method for controlling Plutella xylostella based on a reduction-responsive nano-acetamiprid pesticide, including the following steps:

[0010] Prepare a reduction-responsive nano-acetamiprid pesticide solution, and then apply it as a pesticide to the leaves of crops for cultivation to control Plutella xylostella.

[0011] In an embodiment of the present invention, the reduction-responsive nano-acetamiprid pesticide solution is an aqueous solution of the reduction-responsive nano-acetamiprid pesticide, with a concentration of 25 - 100 mg / L.

[0012] In an embodiment of the present invention, the dosage of the reduction-responsive nano-acetamiprid pesticide solution is 20 - 50 mL / plant.

[0013] In an embodiment of the present invention, the application period is when the Chinese cabbage grows to 15 - 25 days.

[0014] In an embodiment of the present invention, the crop is Chinese cabbage.

[0015] In an embodiment of the present invention, the number of Plutella xylostella in the crop is 5 - 15 per plant.

[0016] In an embodiment of the present invention, the preparation method of the reduction-responsive nano-acetamiprid pesticide includes the following steps:

[0017] First, prepare a mesoporous silica nano-carrier and didodecyl disulfide, then modify the mesoporous silica nano-carrier with a thiol group, and then use didodecyl disulfide to block the thiol-modified mesoporous silica nano-carrier. Finally, it is compounded with acetamiprid to prepare a reduction-responsive nano-acetamiprid pesticide.

[0018] In one embodiment of the present invention, the preparation method of the reduction-responsive nano-acetamiprid pesticide specifically comprises the following steps:

[0019] (1) Dissolve acetamiprid (Ace) in ethanol to obtain an acetamiprid solution;

[0020] (2) Add a thiol-modified mesoporous silica nanocarrier (MSN-SH) to the acetamiprid solution, perform ultrasonic treatment and vortex oscillation to obtain a mixture; centrifuge, wash, and freeze-dry the mixture under vacuum to obtain a product;

[0021] (3) Disperse the product in ethyl acetate, add didodecyl disulfide, and perform vortex oscillation reaction. After the reaction, centrifuge, wash, collect the precipitate, and quickly freeze-dry to obtain the reduction-responsive nano-acetamiprid pesticide.

[0022] Wherein the ratio of acetamiprid (Ace) to ethanol is 2 mg: 1 mL;

[0023] The mass ratio of acetamiprid to the thiol-modified mesoporous silica nanocarrier is 1:1;

[0024] The volume ratio of ethyl acetate to didodecyl disulfide is 1 mL: 50 μL.

[0025] In one embodiment of the present invention, the preparation method of the thiol-modified mesoporous silica nanocarrier in step (2) is as follows:

[0026] Disperse the CTAB@MSNs carrier in absolute ethanol, and reflux and react with (3-mercaptopropyl) trimethoxysilane (MPTMS) under nitrogen protection to prepare a thiolated mesoporous silica carrier MSN-SH, and then use the acid extraction method to remove the CTAB template;

[0027] Among them, the preparation method of the CTAB@MSNs carrier is to use cetyltrimethylammonium bromide (CTAB) as a template to prepare a mesoporous silica nanocarrier with a two-dimensional tubular pore structure containing the template.

[0028] In one embodiment of the present invention, in step (2), ultrasonic treatment is performed for 30 min, and rotary oscillation is performed at room temperature for 24 h (150 r / min).

[0029] In one embodiment of the present invention, in step (2), centrifugation is performed at 8000 rpm for 15 min, and washing is performed with deionized water.

[0030] In one embodiment of the present invention, in step (3), the rotary oscillation reaction is performed at room temperature for 24 h.

[0031] In one embodiment of the present invention, in step (3), centrifugation is carried out at 8000 rpm for 10 min, and washing is carried out with deionized water and absolute ethanol respectively.

[0032] The second object of the present invention is the application of the method described in the present invention in the field of agricultural pest control.

[0033] [Beneficial effects]

[0034] (1) The present invention can effectively control Plutella xylostella, and at the same time can greatly reduce the residue of acetamiprid pesticide, ensuring the safety of leafy vegetables.

[0035] (2) The Zeta potential of the reduction-responsive nano-acetamiprid pesticide (Ace@MSN-SS-C10) used in the present invention is -32.6 ± 1.7 mV, and its hydrodynamic diameter is 180.0 ± 9.8 nm, having better dispersion performance in water.

[0036] (3) The reduction-responsive nano-acetamiprid pesticide (Ace@MSN-SS-C10) used in the present invention has good long-term storage stability in terms of pH, temperature, and light.

[0037] (4) In the case of Plutella xylostella infesting pakchoi, the use of the reduction-responsive nano-acetamiprid pesticide (Ace@MSN-SS-C10) can effectively increase the reduction rate of Plutella xylostella population and the control effect; and after 72 h of Plutella xylostella infestation, under the treatments of 25, 50, and 100 mg / L Ace@MSN-SS-C10 / plant, the reduction rates of Plutella xylostella population are 67.5%, 85%, and 90% respectively, and the control effects on Plutella xylostella are 53.6%, 78.6%, and 85.7% respectively, indicating that the reduction-responsive nano-acetamiprid pesticide has a high control effect on Plutella xylostella and can prevent Plutella xylostella in the early stage. Description of the drawings

[0038] Figure 1 It is the transmission electron microscopy characterization of the mesoporous silica nanocarrier (MSN) and the nano-acetamiprid pesticide (Ace@MSN-SS-C10) in Example 1; where (A) is MSN; (B) is Ace@MSN-SS-C10.

[0039] Figure 2 It is the Zeta potential (A) and hydrodynamic diameter (B) of MSN, MSN-SH, MSN-SS-C10, and Ace@MSN-SS-C10 in Example 1.

[0040] Figure 3 It is the thermogravimetric analysis diagram of MSN, MSN-SH, and MSN-SS-C10 in Example 1; where (A) is the weight loss rate; (B) is the differential thermogravimetry.

[0041] Figure 4 To study the in vitro release of nano-acetamiprid pesticide induced by different concentrations of exogenous GSH.

[0042] Figure 5 To determine the stability of nano-acetamiprid pesticide (Ace@MSN-SS-C10); among them, (A) pH stability; (B) temperature stability; (C) light stability; (D) long-term storage stability.

[0043] Figure 6 To study the effect of nano-acetamiprid pesticide (Ace@MSN-SS-C10) on the control efficiency of Plutella xylostella, among which (A) the reduction rate of Plutella xylostella population; (B) the control effect on Plutella xylostella. Detailed implementation manners

[0044] The following are descriptions of the preferred embodiments of the present invention. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0045] 1. TEM test:

[0046] Dissolve 10 mg of the nanomaterial in deionized water to prepare a 100 mg / L suspension. After vortexing, ultrasonicate for 2 hours at 35 kV, then use a pipette to aspirate an appropriate amount onto a copper grid and let it dry naturally. Then, take the transmission electron microscope (TEM) image of the nanoparticles on a transmission electron microscope at an acceleration voltage of 100 kV.

[0047] 2. Zeta potential and hydrodynamic diameter test:

[0048] Dissolve 10 mg of the nanomaterial in deionized water to obtain a 100 mg / L suspension, then vortex the suspension evenly and ultrasonicate for 2 hours at 35 kV. Then, aspirate 1 ml of the suspension into a potential cup and a cuvette respectively, and use a Malvern nanoparticle size analyzer (Nano-ZS90, Malvern Instruments, Malvern, UK) to measure the nano Zeta potential and hydrodynamic diameter of the material.

[0049] 3. Specific surface area and pore size test:

[0050] The porosity of the sample was studied by measuring nitrogen adsorption at -196 °C using a surface area and pore size analyzer (Autosorb-iQ, Quantachrome Instruments, USA). Before analysis, the sample was degassed at 40 °C for 12 hours.

[0051] 4. Thermogravimetric analysis test:

[0052] Thermogravimetric analysis (TGA) was used to record the weight loss data of the material as a function of temperature. 5 mg of the nano-pesticide was weighed into a small crucible, and then the small crucible was placed in a heating furnace. After that, the temperature was increased from 40 °C to 600 °C at a heating rate of 10 °C / min and a nitrogen gas flow rate of 20 mL / min.

[0053] 5. Stability tests:

[0054] (1) pH stability test:

[0055] 5 mg of Ace@MSN-SS-C10 was uniformly dispersed in 5 mL of deionized water to obtain a suspension; then the suspension was transferred into a dialysis bag (molecular cut-off 5000 Da, diameter 28 mm) and dialyzed in a brown wide-mouth bottle. 40 wt% ethanol aqueous solutions with different pH values (3.0, 5.0, 7.0, 9.0) were used as the release media. At certain time intervals (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 144, 168, 192, 216, 240 hours), 1 mL of the dialysis solution was collected and the same volume of fresh release media was added. Subsequently, the concentration of Ace was measured at 245 nm using a UV-visible spectrometer. Each sample was repeated 3 times.

[0056] (2) Temperature stability test:

[0057] The Ace@MSN-SS-C10 aqueous solution (1 mg / mL) was added to a brown glass bottle and stored at 4 °C, 25 °C, and 54 °C for 14 days to evaluate the storage stability at low or high temperatures. Then, the concentration of Ace was measured at 245 nm using a UV-visible spectrometer. Each sample was repeated 3 times.

[0058] (3) Photo-stability test:

[0059] 50 mg of Ace@MSN-SS-C10 was dispersed in 50 mL of deionized water to obtain a dispersion; the dispersion was poured into a 50 mL quartz tube, and the sample was irradiated under a 20 cm UV lamp (36 W) at room temperature for 0, 1, 2, 4, 6, 8, 10, 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 144 hours. The concentration of Ace was measured at 245 nm using a UV-visible spectrometer. Each sample was repeated 3 times.

[0060] (4) Long-term storage stability:

[0061] To evaluate the long-term stability of the pesticide-loaded system, the Ace@MSN-SS-C10 (1 mg / mL) suspension was placed in a dark, dry, and well-ventilated cabinet for 6 months, and the Ace content was detected every 2 months. Each sample had 3 replicates.

[0062] 6. Test of in vitro release experiment:

[0063] The release amount of Ace in the MSN sample was determined by ultraviolet-visible spectrophotometry;

[0064] 3 mg of the Ace@MSN-SS-C10 (Ace@MSN) sample was placed at the top of a test tube. The liquid in the test tube was separated by an ultrafiltration dialysis tube (3000D) to prevent the nanoparticles from moving to the bottom of the test tube. The liquid in the test tube consisted of 3.5 mL of Milli-Q water and 3.5 mL of GSH solutions with different concentrations (0, 5, 10 mM). The signals at the bottom of the test tube were recorded at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and 24 h, and the absorbance of Ace was measured at λmax = 245 nm. The final release curve was the average of 3 replicates.

[0065] The commercially available Ace (40% acetamiprid water dispersible granules) and pure Ace (97%) used in the examples were purchased from Qingdao Henderson Biotechnology Co., Ltd. and Shanghai Macklin Biochemical Co., Ltd., respectively.

[0066] Example 1

[0067] A preparation method of a reduction-responsive nano-acetamiprid pesticide, comprising the following steps:

[0068] (1) Preparation of mesoporous silica nanocarrier MSN:

[0069] 2.96 g of cetyltrimethylammonium bromide was dissolved in 100 mL of Milli-Q water, and its pH value was adjusted to 10.0 with ammonium hydroxide. Then it was heated to 80 °C and kept for 30 minutes under stirring to obtain a mixture;

[0070] The temperature of the mixture was lowered to 30 °C at room temperature with stirring, and 1.86 mL of tetraethyl orthosilicate (TEOS) was added dropwise. The reaction was carried out for 24 hours at a stirring speed of 550 rpm, and then aged at 80 °C for 24 hours to obtain a reaction product;

[0071] The reaction product solution was filtered through a nitrocellulose membrane with a pore size of 100 nm (Whatman TM ) filtration, and washed 3 times by centrifugation with absolute ethanol (8000 rpm, 15 min) to obtain white MSNs containing the template (CTAB@MSNs);

[0072] CTAB@MSNs were calcined at 600 °C for 5 hours to prepare template-free mesoporous silica nanocarriers MSN, which were then cooled to room temperature for standby.

[0073] (2) Preparation of thiol-modified mesoporous silica nanocarriers (MSN-SH)

[0074] 100 mg of CTAB@MSNs were dispersed in 100 mL of absolute ethanol and ultrasonically dispersed to obtain a uniform suspension. Then, the suspension was vigorously stirred at room temperature, and 100 μL of MPTMS was added dropwise to the suspension. After 1 h, 1 mL of water was added, and the reaction was continued by stirring at room temperature for 24 h to obtain a mixture. Then, the mixture was heated to 80 °C to obtain a white precipitate product, which was centrifuged at 8000 r / min for 10 min, washed 3 times with absolute ethanol, redissolved in a mixture of 100 mL of absolute ethanol and 1 mL of hydrochloric acid (32%), and stirred overnight at 60 °C to obtain a reaction solution (removing the template CTAB). Finally, the reaction solution was centrifuged in a 50 mL centrifuge tube at 8000 rpm for 7 min, washed 3 times with absolute ethanol, and vacuum dried at room temperature to obtain thiol-functionalized MSN, which was named MSN-SH.

[0075] (3) Synthesis of didecyl disulfide:

[0076] 0.8 mL of decanethiol was stirred and dissolved in 12 mL of ethyl acetate to obtain a mixture. 6 mg of sodium iodide and 0.44 mL of hydrogen peroxide (30 wt%) were added to the mixture. After stirring at room temperature for 30 min, didecyl disulfide was obtained. The synthesized didecyl disulfide was washed 3 times with 10 wt% aqueous sodium carbonate solution, and ethyl acetate was evaporated by silica gel column chromatography at room temperature to collect the final transparent oily product didecyl disulfide.

[0077] (4) Preparation of decanethiol-capped mesoporous silica nanoparticles MSN-SS-C10

[0078] 10 mg of MSN-SH was weighed and dispersed in 10 mL of ethyl acetate, and then 25 μL of didecyl disulfide was added. The mixture was ultrasonically treated at room temperature for 1 h and magnetically stirred at room temperature for 24 h to obtain a mixture. Then, the mixture was washed and centrifuged 3 times with ethyl acetate and absolute ethanol respectively. Finally, the powder was collected by vacuum freeze-drying. The obtained powder was decanethiol-capped mesoporous silica nanoparticles (MSN-SS-C10) with gated molecules.

[0079] (5) Preparation of reduction-responsive nano-acetamiprid pesticide Ace@MSN-SS-C10:

[0080] Dissolve 200 mg of pure acetamiprid (Ace) in 100 mL of ethanol to obtain an acetamiprid (Ace) solution; then add 100 mg of MSN-SH to the Ace solution, sonicate for 30 min, and rotate and oscillate at room temperature for 24 h (150 r / min) to obtain a mixture; then centrifuge the mixture at 8000 rpm for 15 min, wash the separated precipitate 3 times with deionized water, and freeze-dry under vacuum to obtain a product; then ultrasonically disperse the obtained product in 50 mL of ethyl acetate, add 250 μL of didecyl disulfide to the mixture, continue to rotate and oscillate at room temperature for 24 h, after the reaction is completed, centrifuge (8000 rpm, 10 min), wash 3 times with ethyl acetate and absolute ethanol respectively, collect the precipitate, and quickly freeze the precipitate sample in liquid nitrogen to keep Ace in the mesopores, and then freeze-dry for 24 h to obtain a reduction-responsive nano-acetamiprid pesticide (Ace@MSN-SSC10).

[0081] Comparative Example 1

[0082] A control sample (Ace@MSN) loaded with Ace but without any functionalization of MSN was prepared according to the method of Example 1.

[0083] The CTAB@MSNs, MSN, MSN-SH, MSN-SS-C10, Ace, Ace@MSN, and Ace@MSN-SS-C10 prepared in Example 1 and Comparative Example 1 were tested, and the test results are as follows:

[0084] Figure 1 TEM images of MSN and Ace@MSN-SS-C10. From Figure 1 it can be seen that: the average size of MSN is 17 nm ( Figure 1 in A), and the average size of Ace@MSN-SS-C10 is 20 nm ( Figure 1 in B).

[0085] Figure 2 Zeta potential and hydrodynamic diameter of MSN, MSN-SH, MSN-SS-C10, and Ace@MSN-SS-C10. From Figure 2 it can be seen that: the Zeta potential of MSN is reversed from 39.9 ± 2.9 mV of CTAB@MSNs to -33.5 ± 0.7 mV, further confirming the successful formation of the silica shell, and the hydrodynamic diameter of MSN is 555.8 ± 124.3 nm ( Figure 2 in B); the Zeta potential of MSN-SH is negative, -28.6 ± 3.9 mV, confirming the successful modification of thiol groups on MSN; the Zeta potential of Ace@MSN-SS-C10 is -32.6 ± 1.7 mV ( Figure 2In A), its hydraulic diameter is 180.0 ± 9.8 nm, which is lower than that of unmodified MSN (555.8 ± 124.3 nm), indicating that the synthesized nano-acetamiprid pesticide Ace@MSN-SS-C10 has superior dispersibility in water compared to MSN( Figure 2 In B).

[0086] Table 1 shows the test results of the specific surface area and pore volume of MSN, MSN-SH, MSN-SS-C10, and Ace@MSN-SS-C10.

[0087] Table 1 Data of specific surface area and pore volume

[0088] Sample <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Pore volume (cm 3 / g)]]> MSN 413.4±22.2 2.31±0.32 MSN-SH 268.5±16.2 1.44±0.07 MSN-SS-C10 106.2±5.7 0.25±0.02 Ace@MSN-SS-C10 10.0±2.1 0.03±0.003

[0089] Figure 3 are the thermogravimetric analysis diagrams of MSN, MSN-SH, and MSN-SS-C10. From Figure 3 it can be seen that: MSN, MSN-SH, and MSN-SS-C10 reach a plateau above 600 °C, and their weight losses are approximately 0.47%, 17.53%, and 70.39% respectively. The weight loss of MSN, MSN-SH, and MSN-SS-C10 samples below 200 °C is less than 2.0% due to the evaporation of crystal water and interlayer water. The weight loss of MSN-SH between 200 °C and 600 °C (about 15.68%) can be attributed to the loss of MPTMS, while only 0.08% of the weight loss of MSN is due to the decomposition of hydroxyl groups on MSN. The weight loss of MSN-SS-C10 at 520 - 790 °C is attributed to the decomposition of the alkyl chain of decanethiol and the disulfide bond. It is found that the starting position of the first weight loss of MSN-SS-C10 and MSN-SH is the same, indicating the presence of residual -SH groups on MSN. By comparing the weight loss of MSN and MSN-SH, and MSN and MSN-SS-C10, the weight loss rates of -SH groups are calculated to be 17.07% and 5.99% respectively. The weight loss of -SH groups on MSN-SS-C10 accounts for 35.11% of that on MSN-SH, indicating that more than half of the -SH groups (64.89%) on MSN-SH react with didodecyl disulfide to form a "gatekeeper" that blocks guest molecules.

[0090] Figure 4 is the in vitro release of nano-acetamiprid pesticide induced by different concentrations of exogenous GSH. From Figure 4It can be seen that: in the absence of GSH, the release rate of Ace in Ace@MSN-SS-C10 within 24 hours was only 2.20%, indicating that Ace was effectively confined in the pores of MSN due to the blockage of the "gatekeeper" molecule disulfide bond. With the increase of GSH concentration, the release amount of Ace@MSN-SS-C10 in 10 mM GSH was higher than that in 5 mM GSH within the same time, indicating that the increase of GSH concentration would accelerate the cleavage of -SS- and promote the release of Ace. In the Ace@MSN sample of Comparative Example 1, the cumulative release rate of Ace within 24 hours exceeded 85%, indicating that the release of Ace in MSN without a "gatekeeper" was almost instantaneous and rapid. However, by introducing 5 mM and 10 mM GSH, the release of Ace from Ace@MSN-SS-C10 was continuous and slowly increasing. This shows that decanethiol as a gatekeeper can block Ace in the pores of MSN, and the -SS- between MSN and decanethiol can be cleaved by GSH, thus inducing the release of the guest molecule. The "gatekeeper"-blocked MSN as a potential delivery system can encapsulate pesticides in the mesopores without premature release before GSH removes the gatekeeper. Therefore, under pest stress conditions, when GSH accumulates to a certain concentration in plants, this reductive MSN delivery system carrying Ace will be activated.

[0091] Figure 5 For the stability determination of the nanoacetamiprid pesticide (Ace@MSN-SS-C10), including: (A) pH stability; (B) temperature stability; (C) light stability; (D) long-term storage stability. From Figure 5 It can be seen that: the nanoacetamiprid pesticide (Ace@MSN-SS-C10) has good pH, temperature, light and long-term storage stability.

[0092] Example 2

[0093] A method for controlling Plutella xylostella based on a reduction-responsive nanoacetamiprid pesticide, comprising the following steps:

[0094] Disinfect the pakchoi seeds with 5% NaClO solution for 10 min, rinse them clean and evenly sprinkle them into a flower pot with 350 g of soil, and germinate them in the dark in a greenhouse; after they grow well, thin out the seedlings, and keep one pakchoi plant in each pot;

[0095] The reduced-responsive nano-acetamiprid pesticide (Ace@MSN-SS-C10) prepared in Example 1 was formulated into aqueous solutions of reduced-responsive nano-acetamiprid pesticides with concentrations of 25, 50, and 100 mg / L. After the pak choi grew for 21 days, spraying treatment was carried out, and 30 mL was sprayed on the leaf surface of each pak choi plant. After spraying, 10 third-instar diamondback moths of the same size were inoculated on each pak choi plant, and they were covered with a 48-μm fine mesh bag to prevent the diamondback moths from escaping; then cultivation was carried out.

[0096] Deionized water was used to replace the aqueous solution of the reduced-responsive nano-acetamiprid pesticide for spraying, and diamondback moths were inoculated as the control group.

[0097] Each group was repeated 4 times.

[0098] The survival numbers of diamondback moths were recorded 24, 48, and 72 h after inoculating the insects.

[0099] The reduction rate of insect population and the control effect were calculated according to the following formula:

[0100] Reduction rate of insect population (%) = (Initial insect population - Surviving insect number after treatment) / Initial insect population × 100

[0101] Control effect (%) = (Reduction rate of insect population in treatment area - Reduction rate of insect population in control area) / (100 - Reduction rate of insect population in control area) × 100.

[0102] The results are as Figure 6 , from Figure 6 it can be seen that: with the increase of the infection time of diamondback moths, under all Ace@MSN-SS-C10 treatments, the reduction rate of insect population and the control effect of diamondback moths increased significantly. Especially 72 h after the diamondback moths were infected, under the treatments of 25, 50, and 100 mg / L Ace@MSN-SS-C10 / plant, the reduction rates of insect population of diamondback moths were 67.5%, 85%, and 90% ( Figure 6 in A), and the control effects on diamondback moths were 53.6%, 78.6%, and 85.7% ( Figure 6 in B), indicating that Ace@MSN-SS-C10 has a high control effect on diamondback moths and can prevent diamondback moths in the early stage.

[0103] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various modifications and decorations without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. A method for controlling Plutella xylostella based on a reduction-responsive nano-acetamiprid pesticide, characterized in that, it includes the following steps: Prepare the reduction-responsive nano-acetamiprid pesticide into a reduction-responsive nano-acetamiprid pesticide solution, and then apply it as a pesticide to the leaves of the crop for cultivation to control Plutella xylostella; The preparation method of the reduction-responsive nano-acetamiprid pesticide specifically includes the following steps: (1) Dissolve acetamiprid in ethanol to obtain an acetamiprid solution; (2) Add a thiol-modified mesoporous silica nanocarrier to the acetamiprid solution, perform ultrasonic treatment and vortex oscillation to obtain a mixture; centrifuge, wash, and freeze-dry the mixture under vacuum to obtain a product; (3) Disperse the product in ethyl acetate, add didodecyl disulfide, and perform vortex oscillation reaction. After the reaction is completed, centrifuge, wash, collect the precipitate, and quickly freeze-dry to obtain the reduction-responsive nano-acetamiprid pesticide; wherein, the ratio of acetamiprid to ethanol is 2 mg: 1 mL; the mass ratio of acetamiprid to the thiol-modified mesoporous silica nanocarrier is 1: 1; the volume ratio of ethyl acetate to didodecyl disulfide is 1 mL: 50 μL.

2. The method according to claim 1, characterized in that, the reduction-responsive nano-acetamiprid pesticide solution is an aqueous solution of the reduction-responsive nano-acetamiprid pesticide, and the concentration is 25-100 mg / L.

3. The method according to claim 1, characterized in that, the dosage of the reduction-responsive nano-acetamiprid pesticide solution is 20-50 mL / plant.

4. The method according to claim 1, characterized in that, the crop is pakchoi.

5. The method according to claim 1, characterized in that, the number of Plutella xylostella in the crop is 5-15 heads / plant.

6. The method according to claim 1, characterized in that, the application period is when the pakchoi grows to 15-25 days.

7. Application of the method according to any one of claims 1-6 in the field of agricultural pest control.

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