Preparation of volatile slow-release agent pellets and application thereof in pest control

Abstract

The present application belongs to the technical field of plant protection, and particularly relates to a preparation of volatile slow-release agent small balls and application thereof in pest control. The present application uses phenylacetonitrile as a plant volatile induced by pests, and utilizes the dense small balls formed by dehydration shrinkage and long-time mechanical stirring of sodium alginate to wrap the volatile inside, so as to achieve the slow-release effect. The prepared phenylacetonitrile slow-release agent small balls have the advantages of good slow-release effect, long release time, controllable release rate, etc., and are non-toxic, low in cost, simple in preparation method and suitable for industrialized production. In the field application process, the pest population density of tea trees can be significantly reduced, the pest control effect is obvious, when the tea tree pests break out, the branch damage rate can be effectively reduced, the leaf damage degree can be reduced, and the yield loss of fresh tea leaves can be reduced, and the present application shows a good application prospect in the green pest control of tea.

Description

Technical Field

[0001] The invention belongs to the technical field of plant protection, and particularly relates to the preparation of a volatile slow-release agent pellet and the application of the pellet in preventing and controlling pests. Background Art

[0002] Tea trees prefer warm, humid climates and are primarily found in subtropical and tropical regions with warm climates and abundant rainfall. An environment suitable for tea growth also fosters the growth and reproduction of tea insects. Currently, over 800 species of tea pests and mites have been reported, posing a serious threat to tea production and resulting in an annual yield reduction of 11%-55%. Severe pest infestations also lead to the overuse of pesticides, resulting in residual residues and compromising the safety of tea.

[0003] As a natural drink that is beneficial to health, tea has attracted people's attention for its green and pollution-free properties. Therefore, it is crucial to develop green and environmentally friendly tea pest control measures. Among them, the development of botanical pesticides based on pest-inducing plant volatiles has the advantages of specificity, natural enemy friendliness, high safety, difficulty in developing drug resistance, and low environmental pollution. However, the research on the anti-insect effect of pest-inducing plant volatiles on tea tree pests is still in the laboratory stage, and there are few practical applications in tea gardens. The main reason why the existing pest-inducing plant volatiles are difficult to promote in tea gardens is: there is a lack of effective and broad-spectrum pest-resistant pest-inducing plant volatiles, and the slow-release agents produced are low in efficiency and high in cost. Therefore, the development of pest-inducing plant volatile anti-insect strategies that can be applied in actual production is of great significance for the control of tea pests. Summary of the Invention

[0004] In order to overcome the above-mentioned deficiencies of the prior art, the present invention proposes a method for preparing volatile slow-release agent pellets. The prepared volatile slow-release agent pellets have good slow-release effect and significant insect resistance against tea tree pests, and are expected to be used in tea pest control.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The first aspect of the present invention provides a method for preparing volatile sustained-release pellets, comprising the following steps:

[0007] S1. Add phenylacetonitrile, sodium alginate, sunflower oil and antioxidant into water and homogenize to form an emulsion;

[0008] S2. Add the emulsion in step S1 to a calcium chloride aqueous solution to obtain gelled pellets, which are dried to prepare volatile sustained-release pellets (benzeneacetonitrile sustained-release pellets).

[0009] Preferably, the concentrations of the benzyl cyanide, sodium alginate, sunflower oil and antioxidant in water are 0.1-0.2 g / L, 10-20 g / L, 200-250 mL / L and 8-12 g / L, respectively.

[0010] Preferably, the antioxidant includes but is not limited to tert-butylhydroquinone.

[0011] Preferably, the homogenization is carried out at 5000-7000 r / min for 1-3 min.

[0012] Preferably, the concentration of the calcium chloride aqueous solution is 4%-6%.

[0013] The second aspect of the present invention provides volatile sustained-release pellets prepared by the preparation method described in the first aspect.

[0014] The third aspect of the present invention provides the use of the volatile slow-release agent pellets described in the second aspect in controlling tea tree pests.

[0015] The present invention has discovered that using benzyl cyanide as an insect-inducing plant volatile, and utilizing sodium alginate to form dense spheres through syneresis and prolonged mechanical agitation, can encapsulate the volatile, thereby achieving a sustained release effect and significant insect resistance against tea plant pests. Therefore, based on the pest occurrence patterns, damage characteristics, and environmental conditions, simple processing methods can be used to achieve the desired amount, specific time, and sustained and stable release of the insect-resistant volatile, thereby achieving the most economical, safe, and effective control of tea garden pests.

[0016] Preferably, the specific application method is: hang the volatile substance sustained-release agent balls at appropriate positions of the tea tree at intervals and replace them regularly.

[0017] More preferably, the volatile sustained-release agent pellets are hung at a height between the 5th and 7th leaves of the tea plant, with a hanging interval of 2-5 m and a replacement time of every 7-10 days.

[0018] More preferably, the volatile substance sustained-release agent pellets are first placed in a non-woven bag, which is then placed in a small plastic box with a lid and air holes on the side walls, and then hung on the tea tree.

[0019] More preferably, the amount of each volatile sustained-release agent pellet is 10g-20g.

[0020] More preferably, the size of the plastic box is 6.5×6.5×4.5 cm 3 , the air pore size is 1mm.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention discloses a method for preparing volatile sustained-release pellets. Benzyl cyanide is used as an insect pest-inducing plant volatile, and dense pellets are formed by sodium alginate through dehydration and long-term mechanical stirring. The volatiles can be wrapped inside, thereby achieving a sustained-release effect. The prepared benzyl cyanide sustained-release pellets have the advantages of good sustained-release effect, long release time, and controllable release rate. Moreover, they are non-toxic, low-cost, and simple to prepare, making them suitable for industrial production. During field application, the population density of tea tree pests can be significantly reduced, and the anti-insect effect is obvious. When tea tree pests break out, the branch damage rate can be effectively reduced, the degree of leaf damage can be alleviated, and the loss of fresh tea leaf yield can be reduced. The pellets show good application prospects in the green prevention and control of tea pests. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the preparation of benzyl cyanide sustained-release pellets;

[0024] Figure 2 This is the phenotype of the benzyl cyanide sustained-release pellets, scale bar = 1 cm;

[0025] Figure 3 Aerial photo (A) and hanging diagram (B) of the tea garden layout of the phenylacetonitrile slow-release pellets;

[0026] Figure 4 This is the evaluation result of the insect-resistant effect of benzyl cyanide slow-release pellets applied in 'Jinxuan' tea garden;

[0027] Figure 4 In the middle, the statistical square frame (square feet, 0.1m 2 ) within the tea tree pests range, the number of tea leafhopper (A) and tea green leafhopper (B), the rate of tea branch damage, and the degree of leaf damage. 21 days after treatment, the weight of 100 buds and the density of budding were counted in the tea garden sample plots to estimate the yield of fresh tea leaves. The treatment group (T) was hung with phenylacetonitrile slow-release pellets, and one bag of phenylacetonitrile slow-release pellets was placed every 2 meters; the control group (CK) was not treated. Three rows of tea were set up in each treatment group and control group as biological replicates, and each row was 10m (10×1.1×3m 3 Data are presented as mean ± SD (n = 30). ns, not statistically analyzed. Significant differences between the treated and control groups were calculated using Student's T-test and are indicated by *p < 0.05 and **p < 0.01.

[0028] Figure 5 Aerial photo (A) and hanging diagram (B) of the tea garden layout of the phenylacetonitrile slow-release pellets;

[0029] Figure 6 This is the evaluation result of the insect resistance effect of benzyl cyanide slow-release pellets applied in 'Hongyan No. 12' tea garden.

[0030] Figure 6 In the middle, the statistical square frame (square feet, 0.1m 2 ) within the tea tree pests range, the number of tea leafhopper (A) and tea green leafhopper (B), the rate of tea branch damage, and the degree of leaf damage. 31 days after treatment, the weight of 100 buds and the density of budding of tea leaves in the tea garden sample plot were counted to estimate the yield of fresh tea leaves. The treatment group (T) was hung with phenylacetonitrile slow-release pellets, and one bag of phenylacetonitrile slow-release pellets was placed every 2 meters; the control group (CK) was not treated. Three rows of tea were set up in each treatment group and control group as biological replicates, and each row was 10m (10×1.1×3m 3 Data are presented as mean ± SD (n = 30). ns, not statistically analyzed. Significant differences between the treated and control groups were calculated using Student's T-test and are indicated by *p < 0.05 and **p < 0.01. DETAILED DESCRIPTION

[0031] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0032] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0033] Example 1 Preparation of Benzyl Acetonitrile Sustained Release Pellets

[0034] like Figure 1 As shown, the preparation method of the benzyl cyanide sustained-release pellets comprises the following steps:

[0035] (1) Place 6 g of sodium alginate, 4 g of tert-butylhydroquinone, and 86 mL of sunflower oil in a beaker, add distilled water to 400 mL, and then add 0.4 mL of benzyl cyanide (100 mg / mL);

[0036] (2) Use a high-speed dispersing homogenizer (FJ300-SH) at 6000 r / min for 1-3 min to stir it into a thin and uniform emulsion;

[0037] (3) Use a 3 mm diameter plastic tube to pump the emulsion into 1 L of 5% CaCl2 solution (w / v) via a peristaltic pump (iPump 2S, DG-2B). Keep the distance between the end of the plastic tube and the liquid surface of the CaCl2 solution at about 20 cm.

[0038] (4) Place the CaCl2 solution on a magnetic stirrer (RH basic 1). When the emulsion falls into the surging CaCl2 solution, uniform and uniform white balls (about 3 mm in diameter, Figure 2 ), the prepared sustained-release pellets were placed in a CaCl2 solution for more than 2 h to maintain their stability.

[0039] (5) Then use a gauze to filter out the small balls from the solution, place them on filter paper to dry for 10 minutes, and bag them for later use.

[0040] Experimental Example 1 Evaluation of the anti-insect effect of benzyl cyanide sustained-release pellets in tea gardens

[0041] (1) Experimental time:

[0042] From August 31, 2022 to September 16, 2022, it lasted 21 days.

[0043] (2) Experimental materials:

[0044] 1) The tea tree sample plot selected is the 20-year-old 'Jinxuan' tea variety.

[0045] 2) The benzyl cyanide sustained-release pellets prepared in Example 1.

[0046] (3) Experimental methods

[0047] 1) Experimental arrangement (e.g. Figure 3 shown):

[0048] Weigh 10g of freshly prepared benzyl cyanide sustained-release pellets into a non-woven bag and place it in a small plastic box (6.5×6.5×4.5cm). 3 , with a lid and 1mm diameter air holes on the side wall) to reduce the impact of rainfall on the slow-release pellets. At the same time, holes were punched on the top of the plastic box to pass a rope through it, and after adjusting the height, it was fixed at a position around the 5th leaf of the tea tree. Among them, the treatment group (denoted as T) was hung with benzyl cyanide slow-release pellets, and one bag of benzyl cyanide slow-release pellets was placed every 2 meters; the control group (CK) did not receive any treatment. Both the treatment group and the control group were set up with 3 ridges of tea rows as biological replicates, and each ridge was 10m (10×1.1×3m 3 There was at least one row of tea plants between the treatment and control groups as a barrier. The slow-release pellets were replaced every 7 days.

[0049] 2)Indicator statistics:

[0050] During the field experiment, the plots treated with the slow-release pellets were surveyed and counted 1 to 2 times a week, and the statistics were conducted from 9:00 to 11:00 a.m. Three rows of tea were set up in each treatment group and control group, and 10 square frames (square feet, 0.1 m2) were randomly counted in each row of tea. 2). Specific statistical indicators are as follows:

[0051] a. Insect population density: Randomly count the number of tea pests, such as the gray tea looper and the tea green leafhopper, within the square frame.

[0052] b. Branch damage rate: Randomly count the number of damaged sprouting branches and the total number of sprouting branches within the square frame. The branch damage rate is expressed as the percentage of damaged sprouting branches within the square frame to the total number of branches.

[0053] c. Leaf damage degree: Randomly count the damage degree of leaves within the square frame (excluding old leaves). Rating the integrity of the tea leaves, with 0 to 4 indicating gradually increasing damage degree:

[0054] Level 0—leaves intact and not eaten;

[0055] Level 1 – Blade integrity estimated to be above 80%;

[0056] Level 2 - The overall integrity of the blade is estimated to be between 50% and 80%;

[0057] Level 3 - The overall integrity of the blade is estimated to be between 20% and 50%;

[0058] Level 4 - The overall integrity of the blade is less than 20%.

[0059] d. 100-bud weight: Count the tea leaves on the 21st day after hanging the phenylacetonitrile sustained-release pellets (September 21, 2022). Randomly select at least 60 branches from each row of tea leaves, trim them into a uniform pattern of one bud and three leaves according to the picking standard, and weigh them using an electronic balance. The formula for calculating the 100-bud weight of tea leaves is as follows:

[0060]

[0061] e. Sprouting density: Randomly count the number of all sprouting branches within the square frame.

[0062] f. Fresh leaf yield: Estimate the tea yield of the treatment and control groups based on the 100-bud weight and germination density calculated on the 21st day (September 21, 2022). The calculation formula is as follows:

[0063]

[0064] (4) Experimental results

[0065] Depend on Figure 4 It can be seen that after the treatment with benzyl cyanide slow-release pellets, the population density of gray tea geometrids on the 'Jinxuan' tea trees was significantly lower than that of the blank control group ( Figure 4 A); After the 9th and 13th day of treatment, the population density of tea green leafhopper in the treatment group was significantly lower than that in the control group, but there was no significant difference in other statistical time periods ( Figure 4 B). Due to an insect pest outbreak in the selected sample site in 2022, the branch damage rate of the control group (no treatment) was as high as over 80% in severe cases, and the leaves were severely damaged. Treatment with the benzyl cyanide slow-release pellets was able to reduce the branch damage rate to a certain extent ( Figure 4 C) and leaf damage degree ( Figure 4 D). At the same time, the yield data of the tea leaves with one bud and three leaves were collected after 21 days of treatment. The results were as follows: the 100-bud weight (fresh weight) of the 'Jin Xuan' tea leaves in the group treated with the benzyl cyanide slow-release pellets was 102.18±9.98g, which was significantly higher than that of the control group (74.97±3.06g). Figure 4 E). In addition, by counting the sprout density within a square foot ( Figure 4 F), the fresh leaf yield of the treatment group was estimated to be 3786.61±722.81 kg / hm 2 , which was significantly higher than that of the blank control group (2617.97±345.05kg / hm 2 )( Figure 4 G).

[0066] Experimental Example 2 Evaluation of the anti-insect effect of benzyl cyanide sustained-release pellets in tea gardens

[0067] (1) Experimental time:

[0068] From May 12, 2023 to June 13, 2023, it lasts 31 days.

[0069] (2) Experimental materials:

[0070] 1) The tea trees selected for the sample plot were the 'Hongyan No. 12' tea variety, which was 4 years old after grafting.

[0071] 2) The benzyl cyanide sustained-release pellets prepared in Example 1.

[0072] (3) Experimental methods

[0073] 1) Experimental arrangement (e.g. Figure 5 The implementation steps are the same as those in Experimental Example 1.

[0074] 2) Index statistics: its implementation steps are the same as those in Experimental Example 1.

[0075] (4) Experimental results

[0076] Depend on Figure 6 It can be seen that after the treatment with benzyl cyanide slow-release pellets, the population density of gray tea geometrids on the 'Hongyan No. 12' tea trees was significantly lower than that of the blank control group ( Figure 6 A); The population density of tea green leafhopper was significantly higher than that of the control group on the 10th and 14th day after treatment, and there was no significant difference at other statistical times ( Figure 6B). Compared with the control group, the benzyl cyanide slow-release pellets can reduce the branch damage rate to a certain extent ( Figure 6 C) and leaf damage degree ( Figure 6 D). At the same time, the yield data of the tea leaves with one bud and three leaves were collected 31 days after treatment. The results showed that the 100-bud weight of the 'Hongyan No. 12' tea in the 2023 benzyl cyanide slow-release pellet treatment group was 139.40±5.15g, which was significantly higher than that of the control group (123.04±5.35g). Figure 6 E). By counting the sprouting density within a square foot ( Figure 6 F), the fresh leaf yield of the treatment group was estimated to be 8429.05±311.60kg / hm 2 , which was significantly higher than that of the control group (6718.02±292.03kg / hm 2 )( Figure 6 G).

[0077] In summary, the benzyl cyanide sustained-release pellets prepared using the method of the present invention have the advantages of good sustained-release effect, long release time, and controllable release rate. The preparation method is simple and easy to implement, and is suitable for industrial production. Furthermore, the pellets can effectively reduce the pest population density and branch damage rate in tea gardens, alleviate the degree of leaf damage, and reduce the loss of fresh tea leaf yield. The pellets have a significant insect-resistant effect and show good application prospects in the green control of tea pests.

[0078] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. Application of a volatile slow-release agent pellet in tea tree pest control, characterized in that: The tea pests are the gray tea geometrid and the tea green leafhopper; the volatile slow-release agent pellets are hung from the 5th to 7th leaf of the tea tree, with a hanging interval of 2-5 m, and are replaced every 7-10 days; the dosage of each volatile slow-release agent pellet is 10 g-20 g; The preparation method of the volatile sustained-release agent pellets comprises the following steps: S1. Adding benzyl cyanide, sodium alginate, sunflower oil, and an antioxidant to water and homogenizing to form an emulsion; the concentrations of the benzyl cyanide, sodium alginate, sunflower oil, and antioxidant in water are 0.1-0.2 g / L, 10-20 g / L, 200-250 mL / L, and 8-12 g / L, respectively; and the antioxidant is tert-butylhydroquinone; S2. Adding the emulsion in step S1 to a calcium chloride aqueous solution to obtain gelled pellets, which are then dried to prepare volatile sustained-release pellets; the concentration of the calcium chloride aqueous solution is 4%-6%.

2. The use according to claim 1, characterized in that First, put the volatile slow-release agent balls into a non-woven bag, place it in a small plastic box with a lid and air holes on the side wall, and then hang it on the tea tree.

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