Nano-emulsion for preventing and treating grain storage pest prymaria rugosoannulata as well as preparation method and application of nano-emulsion
By encapsulating garlic essential oil in a nanoemulsion using natural tea saponins and combining it with low-temperature ultrasonic emulsification technology, the problems of toxicity, compatibility, and preparation complexity of the nanoemulsion system have been solved, achieving a highly efficient and green control effect against the rust-red flatbread beetle.
Patent Information
- Application Number
- CN202511322765.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-16
- Publication Date
- 2025-12-23
AI Technical Summary
Existing nanoemulsion systems suffer from high toxicity, poor biocompatibility, complex preparation processes, high energy consumption, and low control efficiency, making them difficult to effectively control the rust-red flour beetle, a pest of stored grain.
Using natural tea saponins as emulsifiers, plant-derived garlic essential oil was encapsulated into nanoemulsions. The nanoemulsions were prepared using low-temperature ultrasonic emulsification technology, constructing a stable water-dispersible nanoemulsion system for the control of rust-red flour beetles.
It significantly improves the control efficiency of rusty red flour beetle, with a contact kill rate of ≥97% and a fumigation mortality rate of ≥98%. Moreover, the preparation process is simple, the environmental safety is high, and it is suitable for closed/semi-closed storage scenarios.
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Figure CN121176449A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of green control technology for stored grain pests, specifically to a nanoemulsion for controlling the rusty red flour beetle, its preparation method, and its application. Background Technology
[0002] The rusty red flour beetle (Cryptolestes ferrugineus) is one of the most significant stored-grain pests globally, estimated to cause tens of millions of tons of grain loss annually. Traditional chemical control of the rusty red flour beetle mainly relies on phosphine fumigation and organophosphate insecticides (such as malathion). However, long-term use can easily lead to strong pesticide resistance in the rusty red flour beetle, high rates of residue exceeding standards, and environmental pollution.
[0003] In recent years, plant-derived essential oils have attracted attention due to their low toxicity and easy degradation properties. However, they also suffer from inherent drawbacks such as photosensitive degradation, volatility, water insolubility, and high-temperature inactivation, making them unsuitable for grain storage applications. The introduction of nanotechnology has provided a new pathway for improving insecticide formulations, but traditional nanocarrier materials (such as polymer micelles and solid lipid nanoparticles) have limitations in terms of low essential oil loading capacity, complex preparation processes, or poor biocompatibility, restricting their industrial application. Nanoemulsion encapsulation technology, on the other hand, helps overcome technical barriers related to the solubility, stability, and delivery of lipophilic bioactive substances and has been widely applied in food, nutritional products, pharmaceuticals, and cosmetics.
[0004] However, most existing nanoemulsion systems have the following problems: First, traditional emulsifiers have high toxicity and poor biocompatibility; second, the preparation process of emulsion systems is complex (requiring crude emulsion pretreatment) and energy consumption is high (high-pressure homogenization equipment requires large investment); third, the control efficiency against rust-red flat rice beetle is low (contact kill rate <60%).
[0005] Therefore, there is a lack of green, safe, and highly efficient nanoemulsion systems in the current technology that can be effectively used for the biological control of stored grain pests such as rust beetle and red flour beetle. Summary of the Invention
[0006] To address the aforementioned problems, the purpose of this invention is to provide a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, along with its preparation method and application. The nanoemulsion provided by this invention uses natural tea saponins to encapsulate plant-derived garlic essential oil into a nanoemulsion system, which not only improves the stability of the emulsion but also significantly enhances the control efficiency against the rust-red flour beetle.
[0007] To achieve the above-mentioned technical objectives, the first aspect of the present invention adopts the following technical solution:
[0008] A method for preparing a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grain, includes the following steps:
[0009] Tea saponin was dissolved in water to obtain a tea saponin solution; the tea saponin solution was used as the aqueous phase and garlic essential oil was used as the oil phase; the oil phase was added to the aqueous phase and subjected to low-temperature ultrasonic emulsification to obtain the nanoemulsion used for the control of rust-red grain beetle, a pest in stored grain.
[0010] The mass ratio of tea saponin, water, and garlic essential oil is (1-2):(86-91):(8-12).
[0011] This invention addresses the specific needs of grain storage environments for "low toxicity, long-lasting effect, and easy application" by utilizing nanocarrier technology to solve the industry pain points of poor stability and low utilization rate of plant essential oils. The preparation method of the aforementioned nanoemulsion utilizes natural tea saponins to encapsulate plant-derived active essential oils (garlic oil) into nanoemulsions, constructing a novel nanoemulsion system with water dispersibility and atomization capabilities. The resulting nanoemulsion has a particle size in the range of 200-400 nm, which can improve the penetration of active ingredients into the body wall of the rusty red flour beetle. Furthermore, it can achieve continuous control of rusty red flour beetle larvae and adults through simple spraying or fumigation treatment, effectively enhancing the control effect of the rusty red flour beetle.
[0012] Furthermore, this invention proposes a combination technology of "natural emulsifier + low-temperature ultrasound", which uses tea saponin from natural sources as an emulsifier to prepare nano-emulsions encapsulating plant essential oils at low temperatures through ultrasonic cavitation technology. This is used for the green control of the important stored grain pest, the rusty red flour beetle. It can solve the problems of the water insolubility of plant essential oils and the high-temperature inactivation of high-pressure homogenized emulsification, and can provide a green and clean control strategy.
[0013] As a preferred method, the low-temperature ultrasonic emulsification is performed in a low-temperature water bath. Existing essential oil encapsulation processes often employ high-pressure homogenization, which can easily lead to the loss of active ingredients in the essential oils due to high temperatures. This invention utilizes ultrasonic cavitation low-temperature emulsification technology to uniformly disperse natural plant essential oils in a low-temperature medium, thereby forming a stable nanoemulsion system. This not only effectively avoids heat loss of the plant essential oils, but also significantly reduces production energy consumption compared to high-pressure homogenization.
[0014] As a further preferred embodiment, the temperature of the low-temperature water bath is 0–10°C.
[0015] As a preferred method, the low-temperature ultrasonic emulsification is intermittent ultrasonic emulsification.
[0016] As a further preferred method, the power of the intermittent ultrasonic emulsification is 300-400W, the working time to intermittent time ratio is (4-6)s:(4-6)s, and the total processing time of the intermittent ultrasonic emulsification is 3-10min. In this step, the intermittent ultrasonic emulsification is a pulsed ultrasonic treatment. By controlling the pulse mode to be on for (4-6)s and off for (4-6)s, nanoemulsions can be obtained directly without the need for crude emulsion pretreatment, and the loss of activity of essential oils can be avoided.
[0017] To improve the stability of the nanoemulsion and the control effect of the rusty red flour beetle, as a preferred method, the mass ratio of tea saponin, water, and garlic essential oil is 1.5:88.5:10.
[0018] As a preferred embodiment, the particle size of the nanoemulsion is 200–400 nm.
[0019] The second aspect of the present invention is achieved by the following technical solution:
[0020] A nanoemulsion for controlling the rust-red flour beetle, a pest in stored grain, was prepared using the method described above.
[0021] The third aspect of the present invention is achieved by the following technical solution:
[0022] The application of nanoemulsions for the control of the stored grain pest, the red flour beetle, as described above, in the control of the stored grain pest, the red flour beetle.
[0023] As a preferred method for controlling the stored grain pest, the rust-red flour beetle, spraying or fumigation is employed.
[0024] Compared with the prior art, the beneficial effects of the nanoemulsion of the present invention are as follows:
[0025] The method for preparing nanoemulsions provided by this invention improves the water dispersibility and stability of garlic essential oil by encapsulating natural tea saponins; at the same time, it uses low-temperature ultrasonic emulsification technology to effectively avoid the loss of essential oil activity.
[0026] Meanwhile, the preparation process of this invention is simple, and the synergistic effect of tea saponin and plant essential oils significantly improves the control efficiency of rust-red flour beetle compared to traditional essential oil preparations. The prepared nanoemulsion has a contact kill rate of ≥97% and a fumigation mortality rate of ≥98% against rust-red flour beetle. Furthermore, this invention uses tea saponin and plant essential oils as the core components of the nanoemulsion, making its ingredients natural, environmentally safe, and without the risk of exceeding residue limits. Therefore, this invention can provide an industrially feasible solution for green grain storage technology, while also helping to ensure the safety and quality of grain storage, and is particularly suitable for closed / semi-closed storage scenarios such as grain reserves, farm granaries, and household granaries. Attached Figure Description
[0027] Figure 1 This is an appearance diagram of the nanoemulsion for controlling the rust-red grain beetle, a pest in stored grain, provided in Embodiment 1 of the present invention.
[0028] Figure 2 This is an optical micrograph of the nanoemulsion used for controlling the rust-red grain beetle, a pest in stored grain, provided in Example 1 of the present invention. Detailed Implementation
[0029] The technical solutions and effects of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art should understand that the embodiments are only used to illustrate the technical solutions of the present invention and should not be regarded as limiting the scope of protection of the present invention. Based on the following embodiments, all other implementation schemes obtained by those skilled in the art without creative effort, such as implementation schemes obtained by modification, variation or simple substitution, should fall within the scope of protection of the present invention.
[0030] In the following embodiments, "room temperature" is generally understood as 20–35°C. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; unless otherwise specified, the raw materials used are items commonly used in the art or commercially available.
[0031] In the following embodiments of the present invention, tea saponin was purchased from Xi'an Yihe Biotechnology Co., Ltd.; garlic essential oil was from Jiangxi Xinsen Natural Plant Oil Co., Ltd.; Sichuan pepper essential oil was from Jiangxi Baolin Natural Fragrance Co., Ltd.; oregano essential oil was from Jiangxi Jingwang Natural Fragrance Co., Ltd.; mugwort essential oil was from Hubei Chengfeng Chemical Co., Ltd.; and soap bark extract was from Yiruian Company.
[0032] Example 1
[0033] This embodiment provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0034] (1) At room temperature, 1.5 parts by mass of tea saponin were dissolved in 88.5 parts by mass of water and mixed evenly to obtain an aqueous solution of tea saponin, which was used as the aqueous phase; 10 parts by mass of garlic essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and tea saponin in the mixture was 10:88.5:1.5;
[0035] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of rust-red grain beetle in this embodiment; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0036] Example 2
[0037] This embodiment provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0038] (1) At room temperature, 1.5 parts by mass of tea saponin were dissolved in 88.5 parts by mass and mixed evenly to obtain an aqueous solution of tea saponin, which was used as the aqueous phase; 10 parts by mass of garlic essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and tea saponin in the mixture was 10:88.5:1.5;
[0039] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of rust-red grain beetle in this embodiment; wherein, the power of intermittent ultrasonic emulsification is 400W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0040] Comparative Example 1
[0041] This comparative example provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0042] (1) At room temperature, 1.5 parts by mass of tea saponin were dissolved in 88.5 parts by mass of water and mixed evenly to obtain an aqueous solution of tea saponin, which was used as the aqueous phase; 10 parts by mass of Sichuan pepper essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and tea saponin in the mixture was 10:88.5:1.5;
[0043] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of the grain pest rust red flatbread beetle in the comparative example; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0044] Comparative Example 2
[0045] This comparative example provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0046] (1) At room temperature, 1.5 parts by mass of tea saponin were dissolved in 88.5 parts by mass of water and mixed evenly to obtain an aqueous solution of tea saponin, which was used as the aqueous phase; 10 parts by mass of oregano essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and tea saponin in the mixture was 10:88.5:1.5;
[0047] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of the grain pest rust red flatbread beetle in the comparative example; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0048] Comparative Example 3
[0049] This comparative example provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0050] (1) At room temperature, 1.5 parts by mass of tea saponin were dissolved in 88.5 parts by mass and mixed evenly to obtain an aqueous solution of tea saponin, which was used as the aqueous phase; 10 parts by mass of mugwort essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and tea saponin in the mixture was 10:88.5:1.5;
[0051] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of the grain pest rust red flatbread beetle in the comparative example; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0052] Comparative Example 4
[0053] This comparative example provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0054] (1) At room temperature, 0.5 parts by mass of tea saponin were dissolved in 89.5 parts by mass and mixed evenly to obtain an aqueous solution of tea saponin, which was used as the aqueous phase; 10 parts by mass of garlic essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and tea saponin in the mixture was 10:89.5:0.5;
[0055] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of the grain pest rust red flatbread beetle in the comparative example; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0056] Comparative Example 5
[0057] This comparative example provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0058] (1) At room temperature, 10 parts by mass of tea saponin were dissolved in 88.5 parts by mass of water and mixed evenly to obtain an aqueous solution of tea saponin, which was used as the aqueous phase; 1.5 parts by mass of garlic essential oil was used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein, the mass ratio of oil phase, water and tea saponin in the mixture was 1.5:88.5:10;
[0059] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of the grain pest rust red flatbread beetle in the comparative example; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0060] Comparative Example 6
[0061] This comparative example provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0062] (1) At room temperature, 1.5 parts by mass of Tween-80 were dissolved in 88.5 parts by mass of water and mixed evenly to obtain an aqueous solution of Tween-80, which was used as the aqueous phase; 10 parts by mass of garlic essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and Tween-80 in the mixture was 10:88.5:1.5;
[0063] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of the grain pest rust red flatbread beetle in the comparative example; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0064] Comparative Example 7
[0065] This comparative example provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0066] (1) At room temperature, 1.5 parts by mass of polyethylene glycol (PEG400) were dissolved in 88.5 parts by mass of water and mixed evenly to obtain an aqueous PEG solution, which was used as the aqueous phase; 10 parts by mass of garlic essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and PEG in the mixture was 10:88.5:1.5;
[0067] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of the grain pest rust red flatbread beetle in the comparative example; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0068] Comparative Example 8
[0069] This comparative example provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0070] (1) At room temperature, 1.5 parts by mass of sodium dodecylbenzenesulfonate (SDS) were dissolved in 88.5 parts by mass of water and mixed evenly to obtain an SDBS aqueous solution, which was used as the aqueous phase; 10 parts by mass of garlic essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and SDS in the mixture was 10:88.5:1.5;
[0071] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of the grain pest rust red flatbread beetle in the comparative example; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0072] Comparative Example 9
[0073] This comparative example provides a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grains, prepared using a method comprising the following steps:
[0074] (1) At room temperature, 1.5 parts by mass of soap bark extract were dissolved in 88.5 parts by mass and mixed evenly to obtain an aqueous solution of soap bark, which was used as the aqueous phase; 10 parts by mass of garlic essential oil were used as the oil phase. The oil phase was added to the aqueous phase to obtain a mixture; wherein the mass ratio of oil phase, water and soap bark extract in the mixture was 10:88.5:1.5;
[0075] (2) The mixture obtained in step (1) is placed in an ice water bath (0°C) for intermittent ultrasonic emulsification to obtain the nano-emulsion for the control of the grain pest rust red flatbread beetle in the comparative example; wherein, the power of intermittent ultrasonic emulsification is 360W, the working interval time ratio is 5s:5s, and the total processing time of intermittent ultrasonic emulsification is 5min.
[0076] The technical effects achievable by the present invention will be explained below with reference to experimental examples.
[0077] Experimental Example 1: Test of the appearance, morphology, and particle size stability of nanoemulsions
[0078] The appearance of the nanoemulsion prepared in Example 1 for controlling the rust-red flour beetle, a pest in stored grain, is shown in the figure below. Figure 1 As shown. By Figure 1 As can be seen, the emulsion prepared by this invention is uniformly milky white.
[0079] Furthermore, the morphology of the nanoemulsion prepared in Example 1 was analyzed using an optical microscope, and the results are as follows: Figure 2 As shown. By Figure 2 It can be seen that the essential oils in the emulsion prepared by this invention are uniformly dispersed in nanoscale spherical form.
[0080] Furthermore, the initial particle size of the nanoemulsions prepared in Examples 1-2 and Comparative Examples 1-9 was measured using a Malvern nanolaser particle size analyzer. Simultaneously, the nanoemulsions from each example and comparative example were stored at a constant temperature of 25°C for 30 days, and the particle size of each nanoemulsion after storage was measured, and the particle size growth rate was calculated. The results are shown in Table 1.
[0081] Table 1. Particle size and stability test results of the nanoemulsions obtained in the examples and comparative examples.
[0082]
[0083]
[0084] As shown in Table 1, compared with Comparative Examples 1-3, the garlic essential oil emulsion in Example 1 not only has a nanoscale (<500nm) size, but also a smaller particle size increase rate after 30 days of storage, indicating that the garlic essential oil emulsion has good stability. Compared with Example 1, the garlic essential oil emulsion in Comparative Example 4 has droplets in the sub-meter size, and a particle size increase rate of over 45% after 30 days of storage, indicating that changes in the amount of tea saponin have a significant impact on the stability of the emulsion. In addition, the droplet size and particle size increase rate of the garlic essential oil emulsion stabilized by 10% tea saponin in Comparative Example 5 are slightly reduced, but the difference is not significant, indicating that tea saponin plays an important role in reducing droplet size during emulsion preparation. However, the difference in droplet size and particle size increase rate is not significant compared with the emulsion in Example 1, indicating that a small amount (1.5%) of tea saponin is sufficient to prepare a good garlic essential oil nanoemulsion. Compared to Comparative Examples 6-9, the garlic oil emulsion in Example 1 exhibited similar nanodroplets and a comparable increase in particle size, demonstrating that tea saponin has a comparable ability to prepare garlic oil nanoemulsions to synthetic emulsifiers (Tween-80, polyethylene glycol, sodium dodecylbenzenesulfonate) and commercially available soap bark extract emulsifiers.
[0085] Experimental Example 2: Contact kill rate and fumigation mortality rate of nanoemulsion against the rusty red flour beetle.
[0086] This experiment determined the contact kill rate and fumigation mortality rate of the nanoemulsions prepared in Examples 1-2 and Comparative Examples 1-9 against the stored grain pest, the rusty flour beetle. The experimental results are expressed as the average of two parallel experiments.
[0087] The contact kill rate was tested using the filter paper film method. Circular filter paper with a diameter of 9 cm was placed in glass dishes of the same diameter. 1000 μL of the nanoemulsion (diluted 2.5 times with water) from Examples 1-2 and Comparative Examples 1-9 was pipetted onto the filter paper and allowed to air dry for 30 minutes. Thirty adult *Tectus rusty red flour beetles* were placed in each dish without any feed. A glass ring coated with polytetrafluoroethylene was placed in the dish, and an insect-proof net was used to prevent the insects from climbing up. The same volume of water was used as a negative control, and no pesticide was added as a blank control. All glass dishes were kept at 30±2℃ and 75±5% relative humidity in darkness. After 72 hours, the number of dead insects was recorded, and the mortality rate was calculated as follows: Corrected mortality rate (%) = (treatment group mortality rate - control group mortality rate) / (1 - control group mortality rate) × 100%.
[0088] The fumigation mortality test method was as follows: Thirty adult *Tectus rustae* flour beetles were introduced into 300 mL Erlenmeyer flasks pre-coated with polytetrafluoroethylene (PTFE). Then, 100 μL of the nanoemulsion (diluted 2.5 times with water) from Examples 1-2 and Comparative Examples 1-9 was dropped onto a 2×3 cm filter paper strip using a microsyringe. The filter paper strip was quickly suspended 5 cm from the mouth of the Erlenmeyer flask, ensuring the filter paper did not contact the flask wall, and the flask mouth was tightly sealed. A blank control was used without any added agents or solvents. The treated insects were kept at 30±2℃ and 75±5% relative humidity in darkness. After 72 hours, the number of dead insects was recorded, and the mortality rate was calculated: Corrected mortality rate (%) = (Treatment group mortality rate - Control group mortality rate) / (1 - Control group mortality rate) × 100%.
[0089] The test results for contact kill rate and fumigation mortality rate are shown in Table 2.
[0090] Table 2. Results of contact kill rate and fumigation mortality rate of different nanoemulsions against the stored grain pest, the rusty flour beetle.
[0091] Grouping Contact kill rate (%) Fumigation mortality rate (%) Example 1 98.67 100.00 Example 2 97.67 98.67 Comparative Example 1 31.67 18.33 Comparative Example 2 90.00 68.33 Comparative Example 3 86.67 88.33 Comparative Example 4 76.67 83.33 Comparative Example 5 47.67 36.76 Comparative Example 6 78.67 86.33 Comparative Example 7 93.33 91.00 Comparative Example 8 87.67 86.67 Comparative Example 9 86.67 90.33
[0092] Table 2 shows that, compared with the emulsions of Sichuan pepper oil, oregano oil, and mugwort oil in Comparative Examples 1-3, the garlic oil emulsion in Example 1 showed an 8.67%-67% increase in contact kill rate and an 11.67%-81.67% increase in fumigation mortality rate, indicating that garlic oil is more effective in controlling the rusty red flour beetle. Compared with Comparative Example 4, the nanoscale emulsion in Example 1 showed a 22% increase in contact kill rate and a 16.67% increase in fumigation mortality rate against the rusty red flour beetle, indicating that the dosage of tea saponin is crucial. Compared with Comparative Example 5, Example 1 also showed a significantly improved contact and fumigation effect against the rusty red flour beetle, indicating that the simultaneous control of the dosage of garlic oil and tea saponin in the emulsion plays an important role in controlling the rusty red flour beetle. Compared with Comparative Examples 6-9, Example 1 showed a 5.34%-22% increase in contact kill rate and a 9%-13.33% increase in fumigation mortality rate against the rusty red flour beetle. This indicates that compared with Tween-80, polyethylene glycol, sodium dodecylbenzene sulfonate, and soap bark extract, the use of tea saponin in the emulsion has the best contact and fumigation effects against the rusty red flour beetle.
[0093] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a nanoemulsion for controlling the rust-red flour beetle, a pest in stored grain, characterized in that, Includes the following steps: Dissolve tea saponin in water to obtain a tea saponin solution; Using tea saponin solution as the aqueous phase and garlic essential oil as the oil phase, the oil phase was added to the aqueous phase and subjected to low-temperature ultrasonic emulsification to obtain the nanoemulsion used for the control of rust-red flour beetle, a pest in stored grain. The mass ratio of tea saponin, water, and garlic essential oil is (1~2):(86~91):(8~12).
2. The method for preparing the nanoemulsion for controlling the grain pest *Russula fruticosa* according to claim 1, characterized in that, The low-temperature ultrasonic emulsification is performed in a low-temperature water bath.
3. The method for preparing the nanoemulsion for controlling the stored grain pest, the red flour beetle, according to claim 2, is characterized in that... The temperature of the low-temperature water bath is 0~10℃.
4. The method for preparing the nanoemulsion for controlling the grain pest *Russula fruticosa* according to claim 1, characterized in that, The low-temperature ultrasonic emulsification is intermittent ultrasonic emulsification.
5. The method for preparing the nanoemulsion for controlling the stored grain pest, the red flour beetle, according to claim 4, is characterized in that... The power of the intermittent ultrasonic emulsification is 300~400W, the working time to intermittent time ratio is (4~6)s∶(4~6)s, and the total processing time of the intermittent ultrasonic emulsification is 3~10min.
6. The method for preparing the nanoemulsion for controlling the stored grain pest rust-red flour beetle according to claim 1, characterized in that, The mass ratio of tea saponin, water, and garlic essential oil is 1.5:88.5:
10.
7. The method for preparing the nanoemulsion for controlling the stored grain pest rust-red flour beetle according to claim 1, characterized in that, The particle size of the nanoemulsion is 200~400nm.
8. A nanoemulsion for controlling the rust-red flour beetle, a pest in stored grain, prepared by the preparation method described in any one of claims 1 to 7.
9. The application of a nanoemulsion for controlling the stored grain pest *Russula fruticosa* as described in claim 8, characterized in that... Application in controlling the rust-red flat grain beetle, a pest in stored grain.
10. The application of the nanoemulsion for controlling the stored grain pest rust-red flour beetle according to claim 9, characterized in that, When controlling the stored grain pest rust-red flour beetle, the control methods used are spraying or fumigation.