Preparation method and application of ageratum conyzoides extract for preventing and treating beet armyworms

Abstract

The invention provides a preparation method and application of ageratum conyzoides extract for preventing and treating beet armyworms, and relates to the technical field of pest prevention and treatment. The ageratum conyzoides extract is obtained by fermenting fresh ageratum conyzoides stems and leaves with lactic acid bacteria and then carrying out ice-water bath ultrasonic alcohol extraction and heating alcohol extraction by adopting ethanol with different concentrations; the ageratum conyzoides extract and the petroleum ether extraction of the extract can effectively kill beet armyworms, and corresponding components are plant source components, so that the pollution to the environment during use can be effectively reduced, the harm of pesticide residues is comprehensively reduced, and a new direction is provided for prevention and treatment of the beet armyworms.

Description

Technical Field

[0001] The invention relates to the technical field of pest control, and in particular to a preparation method and application of an ageratum leaf extract for controlling beet armyworm. Background Art

[0002] The beet armyworm (Spodoptera exigua Hubner) belongs to the family Noctuidae in the order Lepidoptera and is a worldwide agricultural pest. In addition to damaging cruciferous vegetables, it also seriously harms crops such as corn, cotton, tobacco, flowers and fruit trees.

[0003] At present, chemical pesticides are mainly used to control beet armyworms. Commonly used chemical agents include high-efficiency cypermethrin, flufenoxuron, cis-cypermethrin, badam, cypermethrin, cypermethrin, spinosad and chlorpyrifos, among which insecticides such as high-efficiency cypermethrin, spinosad and chlorpyrifos have developed different degrees of resistance, and some drugs such as cis-cypermethrin and badam are basically ineffective. Although pesticides such as cypermethrin and cypermethrin are still sensitive, long-term and repeated use will also lead to the development of pest resistance, causing problems such as pesticide residues, ecological environment pollution, biodiversity decline, and food safety.

[0004] Botanical pesticides, one of the biological pesticides, have the characteristics of less residue, low toxicity, high selectivity, and not easy to develop resistance. They are a new type of environmentally friendly pesticide with good environmental compatibility. Based on the current prevention and control of beet armyworm, it is very important to develop a new botanical pesticide. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for preparing an ageratum extract for controlling beet armyworm and its application. The ageratum extract is used to control beet armyworm, which can effectively kill the beet armyworm by contact, thereby reducing pollution and ensuring the control effect.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented through the following technical solutions: A method for preparing an ageratum extract for controlling beet armyworm, the method comprising the following steps: S1. Select fresh stems and leaves of Ageratum cochinchinensis, add water and grind into slurry, then inoculate lactic acid bacteria for preliminary fermentation for 6-10 hours to obtain preliminary fermentation material for standby use; S2, drying and crushing the above-mentioned preliminary fermentation material to obtain pre-treated powder for standby use; S3, adding 70%-75% ethanol solution to the pretreated powder under ice bath conditions, ultrasonic extraction in an ice water bath, and then filtering to obtain a first filtrate and a first filter residue for later use; S4, adding the first filter residue to an ethanol solution with a concentration of 95%-100%, performing ultrasonic extraction in an ice-water bath, and then filtering to obtain a second filtrate and a second filter residue for standby use; S5, adding the second filter residue to an ethanol solution with a concentration of 80%-85%, heating to 50-60°C, extracting at this temperature for 10-20 minutes, returning to room temperature and filtering to obtain a third filtrate; S6. Combining the first filtrate, the second filtrate and the third filtrate, and then drying to obtain an ageratum leaf extract.

[0007] Preferably, in step S1, the mass ratio of the slurry to the water-liquid grinding of the stems and leaves of Ageratum cochinchinensis is 1:2-3, and the inoculation amount of lactic acid bacteria in the slurry is 0.2%-0.3% of the total mass of the slurry.

[0008] Preferably, the drying temperature in step S2 is 30-35° C., and the crushed pretreated powder is sieved through a 40-mesh sieve.

[0009] Preferably, the ultrasonic extraction in steps S3 and S4 is performed by treating at an ultrasonic power of 400-600 W for 2-3 min and then standing for 2-3 min, and this operation is repeated 5-8 times to complete the ultrasonic extraction.

[0010] Preferably, the drying method in step S6 is freeze-drying.

[0011] The ageratum extract is used for preventing and controlling beet armyworm.

[0012] Preferably, the application method is to directly use the ageratum extract to control the beet armyworm, or to use the petroleum ether extract of the ageratum extract to control the beet armyworm.

[0013] Preferably, when the Ageratum exigua extract is directly used to control Spodoptera exigua, the LC values ​​of 24 h, 72 h, 120 h, and 168 h for Spodoptera exigua are 50 They are 15.67 mg / mL, 1.54 mg / mL, 0.61 mg / mL and 0.61 mg / mL respectively.

[0014] Preferably, the petroleum ether extract of the ageratum extract is obtained by adding water to the ageratum extract to prepare a suspension, then extracting with petroleum ether, and then removing the solvent.

[0015] Preferably, the petroleum ether extract of the sweet thistle extract is used to control beet armyworm. The LC values ​​of the petroleum ether extract of the sweet thistle extract against beet armyworm at 24 h, 72 h, 120 h, and 168 h are 50 They are 5.69 mg / mL, 3.86 mg / mL, 3.42 mg / mL and 3.13 mg / mL respectively.

[0016] The present invention provides a preparation method of an ageratum leaf extract for controlling beet armyworm and its application, which has the advantages of: The ageratum extract and the petroleum ether extract of the ageratum extract prepared by the present invention have good contact activity against the beet armyworm, and can effectively prevent and control the beet armyworm. The ageratum extract is a plant-derived component, and can effectively reduce the pollution to the environment during use, and comprehensively reduce the harm of pesticide residues, thereby providing a new direction for the prevention and control of the beet armyworm. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Embodiment 1:

[0018] Preparation of Ageratum Extract: (1) Select fresh stems and leaves of Ageratum cochinchinensis, add water and grind into slurry according to the material-liquid mass ratio of 1:2.5, then inoculate 0.2% of the total mass of the slurry with lactic acid bacteria for preliminary fermentation for 8 hours, and obtain preliminary fermentation material for use; (2) drying the above preliminary fermented material at 35°C and then crushing it through a 40-mesh sieve to obtain a pre-treated powder for later use; (3) Add the above pretreated powder to a 75% ethanol solution under ice bath conditions, perform ultrasonic treatment at 400W for 2 minutes under ice water bath conditions, let stand for 2 minutes, perform ultrasonic treatment for 5 times, and then filter to obtain a first filtrate and a first filter residue for later use; (4) Add the first filter residue to a 98% ethanol solution, treat it with 600W ultrasound for 3 minutes in an ice-water bath, let it stand for 3 minutes, repeat the ultrasound treatment for 8 times, and then filter to obtain a second filtrate and a second filter residue for later use; (5) Add the second filter residue to an 85% ethanol solution, raise the temperature to 55°C, extract at this temperature for 15 minutes, return to room temperature and filter to obtain a third filtrate; (6) The first filtrate, the second filtrate, and the third filtrate are combined and freeze-dried to obtain an ageratum leaf extract. Embodiment 2:

[0019] Ageratum Extract Petroleum Ether Extract: The Ageratum extract prepared in Example 1 was added with 5 times the volume of pure water to prepare a suspension, and then petroleum ether was added to the suspension at a volume ratio of 1:3 for extraction, and then the solvent was removed to obtain a petroleum ether extract.

[0020] Comparative Example 1:

[0021] Preparation of Ageratum Extract: (1) Select fresh stems and leaves of Ageratum cochinchinensis, add water at a material-liquid mass ratio of 1:2.5, grind into slurry, dry at 35°C, and then pulverize through a 40-mesh sieve to obtain pre-treated powder for later use; (2) adding a 75% ethanol solution to the pretreated powder under ice bath conditions, subjecting the powder to an ultrasonic treatment at 400 W for 2 min under ice water bath conditions, and then allowing the solution to stand for 2 min, subjecting the solution to a cyclic ultrasonic treatment for 5 times, and then filtering to obtain a first filtrate and a first filter residue for later use; (3) Add the first filter residue to a 98% ethanol solution, treat it with 600W ultrasound for 3 minutes in an ice-water bath, let it stand for 3 minutes, repeat the ultrasound treatment for 8 times, and then filter to obtain a second filtrate and a second filter residue for later use; (4) Add the second filter residue to an 85% ethanol solution, raise the temperature to 55°C, extract at this temperature for 15 minutes, return to room temperature and filter to obtain a third filtrate; (5) The first filtrate, the second filtrate, and the third filtrate are combined and freeze-dried to obtain an ageratum leaf extract. Comparative Example 2:

[0022] Preparation of Ageratum Extract: (1) Select fresh stems and leaves of Ageratum cochinchinensis, add water and grind into slurry according to the material-liquid mass ratio of 1:2.5, then inoculate 0.2% of the total mass of the slurry with lactic acid bacteria for preliminary fermentation for 8 hours, and obtain preliminary fermentation material for use; (2) drying the above preliminary fermented material at 35°C and then crushing it through a 40-mesh sieve to obtain a pre-treated powder for later use; (3) Adding the above pretreated powder to a 98% ethanol solution under ice bath conditions, subjecting the powder to ultrasonic treatment at 400W for 2 minutes under ice water bath conditions, and then allowing the solution to stand for 2 minutes, subjecting the solution to ultrasonic treatment for 18 times, and then filtering to obtain a first filtrate and a first filter residue for later use; (4) Add the first filter residue to an 85% ethanol solution, raise the temperature to 55°C, extract at this temperature for 15 minutes, return to room temperature and filter to obtain a second filtrate; (5) The first filtrate and the second filtrate are combined, and then freeze-dried to obtain an ageratum leaf extract. Comparative Example 3:

[0023] Preparation of Ageratum Extract: (1) Select fresh stems and leaves of Ageratum cochinchinensis, add water and grind into slurry according to the material-liquid mass ratio of 1:2.5, then inoculate 0.2% of the total mass of the slurry with lactic acid bacteria for preliminary fermentation for 8 hours, and obtain preliminary fermentation material for use; (2) drying the above preliminary fermented material at 35°C and then crushing it through a 40-mesh sieve to obtain a pre-treated powder for later use; (3) Add the above pretreated powder to a 75% ethanol solution under ice bath conditions, perform ultrasonic treatment at 400 W for 2 min at room temperature, let stand for 2 min, repeat the ultrasonic treatment for 5 times, and then filter to obtain a first filtrate and a first filter residue for later use; (4) Add the first filter residue to a 98% ethanol solution, treat it with 600W ultrasonic wave for 3 minutes at room temperature, and then let it stand for 3 minutes. Cycle the ultrasonic wave and let it stand for 8 times, and then filter to obtain a second filtrate and a second filter residue for later use; (5) Add the second filter residue to an ethanol solution with a concentration of 85%, extract at room temperature for 15 minutes, and then filter to obtain a third filtrate; (6) The first filtrate, the second filtrate, and the third filtrate are combined and freeze-dried to obtain an ageratum leaf extract. Detection:

[0024] The insecticidal activity of the extracts / extracts prepared in the above Examples 1-2 and Comparative Examples 1-3 against the third instar larvae of Spodoptera exigua was determined by the insect immersion method: The contact activity test was conducted with extracts / extracts of five concentration gradients of 1.25 mg / mL, 2.5 mg / mL, 5.0 mg / mL, 10.0 mg / mL, and 20.0 mg / mL (set as treatment groups); 10 larvae were treated with each concentration of each substance in each group, and repeated 3 times; 0.5% Tween 80 aqueous solution was used as the control group, and pyrethroids were used as the verification group. The survival status of the larvae was checked at 1, 3, 5, and 7 days after treatment, and the adjusted mortality rate of each group was calculated, and the LC was calculated based on the adjusted mortality rate. 50 .

[0025] in: ; The mortality rates of the control group and the treatment group were calculated as follows: .

[0026] The corrected mortality rates of beet armyworm at different concentrations of the extract prepared in Example 1 are shown in Table 1 below: Table 1

[0027] SPSS 23.0 statistical analysis software was used for univariate Anova analysis, followed by regression probability test analysis to obtain the median lethal concentration (LC). 50 , LC 50 95% confidence interval, slope ± standard error, chi-square value ( X 2 ) and P values, as shown in Table 2 below: Table 2

[0028] From the above test, it can be seen that the extracts prepared in Example 1 and Example 2 have good contact toxicity to Spodoptera exigua at lower concentrations.

[0029] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an ageratum leaf extract for controlling beet armyworm, characterized in that: The preparation method of the ageratum leaf extract comprises the following steps: S1. Select fresh stems and leaves of Ageratum cochinchinensis, add water and grind into slurry, then inoculate lactic acid bacteria for preliminary fermentation for 6-10 hours to obtain preliminary fermentation material for standby use; S2, drying and crushing the above-mentioned preliminary fermentation material to obtain pre-treated powder for standby use; S3, adding 70%-75% ethanol solution to the pretreated powder under ice bath conditions, ultrasonic extraction in an ice water bath, and then filtering to obtain a first filtrate and a first filter residue for later use; S4, adding the first filter residue to an ethanol solution with a concentration of 95%-100%, performing ultrasonic extraction in an ice-water bath, and then filtering to obtain a second filtrate and a second filter residue for standby use; S5, adding the second filter residue to an ethanol solution with a concentration of 80%-85%, heating to 50-60°C, extracting at this temperature for 10-20 minutes, returning to room temperature and filtering to obtain a third filtrate; S6. Combining the first filtrate, the second filtrate and the third filtrate, and then drying to obtain an ageratum leaf extract.

2. The preparation method according to claim 1, characterized in that: In step S1, the mass ratio of the slurry to the water-solid ratio of the stems and leaves of Ageratum confusa is 1:2-3, and the inoculation amount of lactic acid bacteria in the slurry is 0.2%-0.3% of the total mass of the slurry.

3. The preparation method according to claim 1, characterized in that: The drying temperature in step S2 is 30-35° C., and the crushed pre-treated powder is sieved through a 40-mesh sieve.

4. The preparation method according to claim 1, characterized in that: The ultrasonic extraction in steps S3 and S4 is performed by treating at an ultrasonic power of 400-600 W for 2-3 minutes and then standing for 2-3 minutes, and this operation is repeated 5-8 times to complete the ultrasonic extraction.

5. The preparation method according to claim 1, characterized in that: The drying method in step S6 is freeze-drying.

6. Use of the Ageratum cochinchinensis extract obtained by the preparation method according to any one of claims 1 to 5 in controlling beet armyworm.

7. The use according to claim 6, characterized in that: The application method is to directly use the ageratum extract to control the beet armyworm, or to use the petroleum ether extract of the ageratum extract to control the beet armyworm.

8. The use according to claim 7, characterized in that: The LC values ​​of the ageratum extract on beet armyworm at 24 h, 72 h, 120 h and 168 h were 50 They are 15.67 mg / mL, 1.54 mg / mL, 0.61 mg / mL and 0.61 mg / mL respectively.

9. The use according to claim 7, characterized in that: The petroleum ether extract of the ageratum extract is obtained by adding water to the ageratum extract to prepare a suspension, then extracting with petroleum ether, and then removing the solvent.

10. The use according to claim 9, characterized in that: The LC values ​​of the petroleum ether extract of the sweet thistle extract against the beet armyworm at 24 h, 72 h, 120 h and 168 h 50 They are 5.69 mg / mL, 3.86 mg / mL, 3.42 mg / mL and 3.13 mg / mL respectively.

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