Preparation method of spirulina biopesticide

Abstract

The invention discloses a preparation method of a spirulina biopesticide, which comprises the following steps: preparing water, spirulina mud, a carbon source and zymophyte, and sequentially putting into a sealed barrel; opening the sealing barrel, uniformly stirring once every day, continuously stirring for 7-10 days, and adding the waste flue-cured tobacco when the mixed liquid is odorless and has acid fragrance; then uniformly stirring once every 7-10 days, and stirring for 3-4 times; finally, uniformly stirring once every 15 days, and sealing for 2-3 months after stirring twice, so as to obtain fermentation liquor; adding a veratrum nigrum extract and a fructus cnidii extract into the fermentation liquid, uniformly mixing, standing and filtering to obtain the spirulina biopesticide. The pesticide has the effect of killing pests, especially aphids, the waste flue-cured tobaccos and the spirulina are fermented by adopting zymophyte mainly comprising candida alcoholism, then the veratrum nigrum extract and the fructus cnidii extract are compounded, the preparation method is simple and effective, the aphids can be killed at low concentration, the use amount of the pesticide is reduced, the pest control cost is reduced, resource reutilization is realized, and the pesticide has a good application prospect. And no chemical agent is used, and low toxicity and environmental protection are realized.

Description

Technical Field

[0001] The invention relates to the technical field of pesticides, and in particular to a method for preparing a spirulina biological pesticide. Background Art

[0002] Aphids, also known as sticky insects or honey insects, belong to the order Hemiptera of the class Insecta of the phylum Arthropoda. There are nearly 5,000 known species of aphids in the world, and more than 1,000 species have been found in my country. Aphids are very harmful to plants. On the one hand, aphids directly harm plants by sucking plant sap or releasing toxic substances, affecting the normal physiological metabolism and growth and development of plants; on the other hand, aphids are the transmission medium of plant pathogens. Most of the extremely common viral diseases of plants are transmitted by aphids, which also increases the harm of aphids to plants.

[0003] The use of chemical pesticides did promote agricultural development in the early stage and improve the weight and quality of agricultural products. With long-term and extensive use, pests and diseases have become more resistant to pesticides, polluted the environment, damaged the ecology, and killed natural enemies, forming a vicious cycle, which seriously damaged the ecosystem. On March 18, 2015, the Ministry of Agriculture and Rural Affairs issued a notice on the issuance of the "Action Plan for Zero Growth in Pesticide Use by 2020". Therefore, it is imperative to develop chemical pesticide alternatives. Biopesticides have attracted worldwide attention due to their compatibility with the environment, do not kill natural enemies, and have little impact on the ecological chain. At the "World Conference on Environment and Development" in 1992, China promised that the domestic use of biopesticides in 2000 will reach more than 60% of the domestic pesticide market, reflecting the attitude of the Chinese government towards biopesticides. Therefore, the development of biopesticides is of great significance to policy commitment, ecological protection, and agricultural development. Summary of the invention

[0004] In view of the market gap, the present invention provides a method for preparing a spirulina biopesticide, which has the function of killing pests, especially aphids. The preparation method is simple and effective, and aphids can be killed at a low concentration, thereby reducing the amount of pesticides used, reducing the cost of pest control, and realizing resource recycling. Moreover, the method does not require chemical preparations and is green, low-toxic and environmentally friendly. The specific technical scheme is as follows:

[0005] A method for preparing a spirulina biopesticide comprises the following steps:

[0006] S1. Prepare water, spirulina mud, carbon source, and fermentation bacteria, and place them in 1m 3 in a sealed barrel;

[0007] S2, open 1m per day 3 Stir once in a sealed barrel for 7-10 days, and add waste flue-cured tobacco when the mixed liquid is odorless and has a sour aroma; stir once every 7-10 days and stir 3-4 times; finally stir once every 15 days, stir twice and seal for 2-3 months to obtain fermentation liquid;

[0008] S3. Add Veratrum extract and Cnidium monnieri extract to the fermentation liquid obtained in step S2, mix well, let stand for 1-3 hours, filter, and prepare Spirulina biopesticide stock solution.

[0009] Preferably, the spirulina biopesticide comprises the following raw materials in parts by weight: 400-600 parts of water, 150-200 parts of spirulina mud, 50-100 parts of waste flue-cured tobacco, 20-30 parts of carbon source, 0.5-2 parts of fermentation bacteria, 1-20 parts of Veratrum extract, and 1-20 parts of Cnidium monnieri extract.

[0010] Preferably, the spirulina biopesticide comprises the following raw materials in parts by weight: 450-550 parts of water, 180-190 parts of spirulina mud, 60-80 parts of waste flue-cured tobacco, 22-38 parts of carbon source, 1-1.8 parts of fermentation bacteria, 5-10 parts of Veratrum extract, and 5-10 parts of Cnidium monnieri extract.

[0011] Preferably, the spirulina biopesticide comprises the following raw materials in parts by weight: 500 parts of water, 185 parts of spirulina mud, 70 parts of waste flue-cured tobacco, 25 parts of carbon source, 1.5 parts of fermentation bacteria, 8 parts of Veratrum extract, and 8 parts of Cnidium monnieri extract.

[0012] Preferably, the waste flue-cured tobacco is a pulverized product of discarded dry flue-cured tobacco straw or tobacco leaves, and the pulverized particle size is less than 1 cm.

[0013] Preferably, the carbon source is one or more of white sugar powder, brown sugar powder and tapioca flour.

[0014] Preferably, the sealed fermentation in step S1 is 2 months in summer and 3 months in winter.

[0015] Preferably, the algae mud is spirulina mud with a water content of 90%.

[0016] The preparation method of Veratrum extract is as follows:

[0017] Wash the Veratrum, dry it, crush it to 100-200 mesh, add water to extract twice, the extraction time is 2-4h, the extraction temperature is 90-100℃, the solid-liquid ratio is 1:10-20, collect the extract, centrifuge it at a speed of 2000-3000r / min for 5-20min, remove the precipitate, collect the supernatant, and concentrate it under reduced pressure to obtain the Veratrum extract. The Veratrum extract prepared by the preparation method contains 6-8% of fenfenamine, 57-62% of veratridine, 8-11% of veratridine, and 8-12% of veratramine.

[0018] The preparation method of Cnidium monnieri extract is as follows:

[0019] Wash the Cnidium monnieri, dry it, crush it to 100-200 mesh, extract it twice with 95% ethanol in a water bath with reflux, the solid-liquid ratio is 1:4-8, the extraction temperature is 50-70°C, the extraction time is 1-3h, collect the extract, let it stand, filter it, and concentrate it under reduced pressure to obtain the Cnidium monnieri extract. The Cnidium monnieri extract prepared by the preparation method contains 10-12% of borneol, 60-63% of osthole, 7-10% of bergamot lactone, and 9-13% of isosaxifen.

[0020] Preferably, the fermentation bacteria comprises the following raw materials in mass percentage: 70-80% of Candida ethanolica, 10-15% of Pichia pastoris, and 10-15% of Bacillus amyloliquefaciens.

[0021] A method of using a spirulina biopesticide is as follows:

[0022] In the early and middle stages of crop growth, when aphids are infested, spray 20-50 ml of pesticide concentrate per mu of land with 4-6 times the volume of water on plant leaves, rhizomes and surrounding soil; in the middle and late stages of crop growth, when aphids are infested, spray 50-80 ml of insecticide per mu of land with 2-3 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, when aphids are infested, spray 30-70 ml of insecticide per mu of land with 4-6 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, when aphids are infested, spray 70-100 ml of insecticide per mu of land with 2-3 times the volume of water on plant leaves, rhizomes and surrounding soil; the pesticide spraying time is after 6 pm every day.

[0023] Preferably, the dilution degree of the spirulina biopesticide is different according to the different growth cycles of the crops, the different types of pests and diseases to be eliminated, and the different degrees of pests.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention provides a method for preparing a spirulina biopesticide, which has the function of killing pests, especially aphids. A fermentation bacteria mainly including Candida alcoholica is used to ferment waste flue-cured tobacco and spirulina mud, and then Veratrum extract and Cnidium monnieri extract are compounded. The preparation method is simple and effective, and can prevent and control aphids, and can achieve the purpose of effectively reducing aphid diseases and pests. Aphids can be killed at a low concentration, the amount of pesticide used is reduced, the cost of pest control is reduced, and resource recycling is realized. Moreover, the method does not require chemical preparations and is green, low-toxic and environmentally friendly.

[0026] 2. Cnidium monnieri mainly contains pinene, borneol, dihydroerucyl alcohol, bergamot lactone, osthole, isosaxifen, isoanisole, etc., which have insecticidal and bactericidal effects, and dampness-drying effects, and have a wide antibacterial and insecticidal spectrum; Veratrum mainly contains interferon, veratridine, veratridine, and veratramine, which have the effects of killing maggots and flies; the applicant found that the combination of Cnidium monnieri extract, Veratrum extract, flue-cured tobacco, and Spirulina can significantly increase the killing and control effect on aphids.

[0027] 3. The present invention ferments spirulina and flue-cured tobacco with fermentation bacteria mainly composed of Candida ethanolica, and fully utilizes microorganisms and organic matter in spirulina mud as auxiliary substances, thereby significantly reducing the amount of fermentation bacteria used. The functions of the fermentation bacteria and algae mud in the scheme of the present invention include not only decomposing flue-cured tobacco and spirulina and assisting flue-cured tobacco and spirulina in releasing effective ingredients, but also including the beneficial effects of pesticides on the soil environment after being applied to the soil around crops. DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0029] Example 1

[0030] The method for preparing the spirulina biopesticide of this embodiment comprises the following steps:

[0031] S1. Prepare water, 90% water content spirulina mud, sugar powder, and fermentation bacteria, and place them in 1m 3 in a sealed barrel;

[0032] S2, open 1m per day 3 Stir once in a sealed barrel for 7 consecutive days, and when the mixed liquid is odorless and has a sour aroma, add waste flue-cured tobacco with a crushed particle size of 0.8 cm; then stir once every 7 days and stir 3 times; finally stir once every 15 days, stir twice and seal for 2 months to obtain fermentation liquid;

[0033] S3. Add Veratrum extract and Cnidium monnieri extract to the fermentation liquid obtained in step S2, mix well, let stand for 1 hour and then filter to prepare Spirulina biopesticide stock solution.

[0034] The spirulina biopesticide of this embodiment includes the following raw materials in parts by mass: 400 parts of water, 150 parts of spirulina mud, 50 parts of waste flue-cured tobacco, 20 parts of white sugar powder, 0.5 parts of fermentation bacteria, 1 part of Veratrum extract, and 1 part of Cnidium monnieri extract; the fermentation bacteria include the following raw materials in percentage by mass: 70% of Candida alcoholica, 15% of Pichia pastoris, and 15% of Bacillus amyloliquefaciens.

[0035] The preparation method of the Veratrum extract of this embodiment is as follows:

[0036] The Veratrum extract is washed, dried, crushed to 100 mesh, and extracted with water twice, the extraction time is 2h, the extraction temperature is 90°C, the solid-liquid ratio is 1:10, the extract is collected, centrifuged at a speed of 2000r / min for 5min, the precipitate is removed, the supernatant is collected, and the Veratrum extract is concentrated under reduced pressure to obtain the Veratrum extract. The Veratrum extract prepared by the preparation method contains 6.2% of fenfenamine, 59.3% of veratridine, 9.0% of veratridine, and 8.9% of veratramine.

[0037] The preparation method of the Cnidium monnieri extract of the present embodiment is as follows:

[0038] Wash the Cnidium monnieri, dry it, crush it to 100 mesh, extract it twice with 95% ethanol in a water bath with reflux, the solid-liquid ratio is 1:4, the extraction temperature is 50°C, the extraction time is 1h, collect the extract, let it stand, filter it, and concentrate it under reduced pressure to obtain the Cnidium monnieri extract. The Cnidium monnieri extract prepared by the preparation method contains 11.5% borneol, 61.3% osthole, 8.1% bergamot lactone, and 9.8% isosaxifen.

[0039] The method of using the spirulina biopesticide of this embodiment is as follows:

[0040] In the early and middle stages of crop growth, when aphids are infested, spray 25 ml of pesticide concentrate per mu of land with 4 times the volume of water on plant leaves, rhizomes and surrounding soil; in the middle and late stages of crop growth, spray 50 ml of insecticide per mu of land with 2 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, spray 30 ml of insecticide per mu of land with 4 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, spray 70 ml of insecticide per mu of land with 2 times the volume of water on plant leaves, rhizomes and surrounding soil; the pesticide spraying time is after 6 pm every day.

[0041] Example 2

[0042] The method for preparing the spirulina biopesticide of this embodiment comprises the following steps:

[0043] S1. Prepare water, 90% water content spirulina paste, cassava flour, and fermentation bacteria, and place them in 1m 3 in a sealed barrel;

[0044] S2, open 1m per day 3 Stir once in a sealed barrel for 10 consecutive days, and when the mixed liquid is odorless and has a sour aroma, add waste flue-cured tobacco with a crushed particle size of 0.8 cm; then stir once every 10 days and stir 4 times; finally stir once every 15 days, stir twice and seal for 3 months to obtain fermentation liquid;

[0045] S3. Add Veratrum extract and Cnidium monnieri extract to the fermentation liquid obtained in step S2, mix well, let stand for 1-3 hours, filter and prepare Spirulina biopesticide stock solution.

[0046] The spirulina biopesticide of this embodiment includes the following raw materials in parts by mass: 600 parts of water, 200 parts of spirulina mud, 100 parts of waste flue-cured tobacco, 30 parts of cassava, 2 parts of fermentation bacteria, 20 parts of Veratrum extract, and 20 parts of Cnidium monnieri extract; the fermentation bacteria include the following raw materials in percentage by mass: 80% of Candida alcoholica, 10% of Pichia pastoris, and 10% of Bacillus amyloliquefaciens.

[0047] The preparation method of the Veratrum extract of this embodiment is as follows:

[0048] The Veratrum extract is washed, dried, crushed to 200 mesh, and extracted with water twice, the extraction time is 4 hours, the extraction temperature is 100°C, the solid-liquid ratio is 1:20, the extract is collected, centrifuged at a speed of 3000r / min for 20 minutes, the precipitate is removed, the supernatant is collected, and the Veratrum extract is concentrated under reduced pressure to obtain the Veratrum extract. The Veratrum extract prepared by the preparation method contains 7.8% of fenfenamine, 59.4% of veratridine, 9.5% of veratridine, and 11.2% of veratramine.

[0049] The preparation method of the Cnidium monnieri extract of the present embodiment is as follows:

[0050] Wash the Cnidium monnieri, dry it, crush it to 200 meshes, extract it twice with 95% ethanol in a water bath with reflux, the solid-liquid ratio is 1:8, the extraction temperature is 50-70°C, the extraction time is 1-3h, collect the extract, let it stand, filter it, and concentrate it under reduced pressure to obtain the Cnidium monnieri extract. The Cnidium monnieri extract prepared by the preparation method contains 11.2% of borneol, 60.9% of osthole, 9.3% of bergamot lactone, and 12.0% of isosaxifen.

[0051] The method of using the spirulina biopesticide of this embodiment is as follows:

[0052] In the early and middle stages of crop growth, when aphids are infested, spray 50 ml of pesticide concentrate per mu of land with 6 times the volume of water on plant leaves, rhizomes and surrounding soil; in the middle and late stages of crop growth, when aphids are infested, spray 80 ml of insecticide per mu of land with 3 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, when aphids are infested, spray 70 ml of insecticide per mu of land with 6 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, when aphids are infested, spray 100 ml of insecticide per mu of land with 3 times the volume of water on plant leaves, rhizomes and surrounding soil; the pesticide spraying time is after 6 pm every day.

[0053] Example 3

[0054] The method for preparing the spirulina biopesticide of this embodiment comprises the following steps:

[0055] S1. Prepare water, 90% water content spirulina paste, brown sugar powder, and fermentation bacteria, and place them in 1m 3 in a sealed barrel;

[0056] S2, open 1m per day 3 Stir once in a sealed barrel for 9 consecutive days, and when the mixed liquid is odorless and has a sour aroma, add waste flue-cured tobacco with a crushed particle size of 0.8 cm; then stir once every 9 days and stir 3 times; finally stir once every 15 days, stir twice and seal for 2.5 months to obtain fermentation liquid;

[0057] S3. Add Veratrum extract and Cnidium monnieri extract to the fermentation liquid obtained in step S2, mix well, let stand for 1-3 hours, filter and prepare Spirulina biopesticide stock solution.

[0058] The spirulina biopesticide of this embodiment includes the following raw materials in parts by mass: 500 parts of water, 185 parts of spirulina mud, 70 parts of waste flue-cured tobacco, 25 parts of brown sugar powder, 4 parts of fermentation bacteria, 8 parts of Veratrum extract, and 8 parts of Cnidium monnieri extract; the fermentation bacteria include the following raw materials in percentage by mass: 75% of Candida alcoholica, 13% of Pichia pastoris, and 12% of Bacillus amyloliquefaciens.

[0059] The preparation method of the Veratrum extract of this embodiment is as follows:

[0060] The Veratrum extract is washed, dried, crushed to 150 mesh, and extracted with water twice, the extraction time is 3 hours, the extraction temperature is 95°C, the solid-liquid ratio is 1:15, the extract is collected, centrifuged at a speed of 2500r / min for 10 minutes, the precipitate is removed, the supernatant is collected, and the Veratrum extract is concentrated under reduced pressure to obtain the Veratrum extract. The Veratrum extract prepared by the preparation method contains 7.2% of fenfenamine, 61.6% of veratridine, 10.3% of veratridine, and 11.5% of veratramine.

[0061] The preparation method of the Cnidium monnieri extract of the present embodiment is as follows:

[0062] Wash the Cnidium monnieri, dry it, crush it to 150 mesh, extract it twice with 95% ethanol in a water bath with reflux, the solid-liquid ratio is 1:6, the extraction temperature is 60°C, the extraction time is 2h, collect the extract, let it stand, filter it, and concentrate it under reduced pressure to obtain the Cnidium monnieri extract. The Cnidium monnieri extract prepared by the preparation method contains 11.7% borneol, 62.8% osthole, 7.7% bergamot lactone, and 11.8% isosaxifen.

[0063] The method of using the spirulina biopesticide of this embodiment is as follows:

[0064] In the early and middle stages of crop growth, when aphids are infested, spray 30 ml of pesticide concentrate per mu of land with 5 times the volume of water on plant leaves, rhizomes and surrounding soil; in the middle and late stages of crop growth, spray 60 ml of insecticide per mu of land with 2.5 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, spray 50 ml of insecticide per mu of land with 5 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, spray 85 ml of insecticide per mu of land with 2.5 times the volume of water on plant leaves, rhizomes and surrounding soil; the pesticide spraying time is after 6 pm every day.

[0065] Comparative Example 1: The difference from Example 3 is that Veratrum extract is not added.

[0066] Comparative Example 2: The difference from Example 3 is that no Cnidium monnieri extract is added.

[0067] Comparative Example 3: The difference from Example 3 is that no waste flue-cured tobacco is added.

[0068] Comparative Example 4: The difference from Example 3 is that no spirulina mud is added.

[0069] Comparative Example 5: The difference from Example 3 is that the fermentation bacteria is Bacillus subtilis.

[0070] Comparative Example 6: The difference from Example 3 is that spirulina mud is replaced by spirulina.

[0071] Comparative Example 7: The difference from Example 3 is that the spirulina mud is replaced by seaweed.

[0072] Comparative Example 8: The difference from Example 3 is that the preparation method of the spirulina biopesticide is different, as follows:

[0073] S1. Prepare water, spirulina mud, carbon source, fermentation bacteria, and waste flue-cured tobacco, and place them in a 1m 3 in a sealed barrel;

[0074] S2, open 1m per day 3 Stir the sealed barrel once for 20 consecutive days, seal it for 2-3 months, and obtain the fermentation liquid;

[0075] S3. Add Veratrum extract and Cnidium monnieri extract to the fermentation liquid obtained in step S2, mix well, let stand for 1-3 hours, filter, and prepare Spirulina biopesticide.

[0076] Pesticide bioactivity assay

[0077] In order to verify the biological activity and aphid control effect of the pesticide of the present invention, the pesticides prepared in Examples 1-3 and Comparative Examples 1-8 were subjected to the following tests.

[0078] Inoculate aphids of the same size onto fresh leaves to ensure that there are 30-35 aphids on each test leaf. Take the original pesticide solution and prepare it into a 30ppm pesticide solution. Spray it evenly at a distance of about 20cm from the leaves. Gently place it in the experimental box and culture it in an incubator with a temperature of 25°C, a relative humidity of 40%, and a light intensity of 18h:6h (L:D). After 4 hours, observe and record the number of live and dead aphids in each treatment group, calculate the mortality rate and lethal concentration LC50 and LC90, LC50 represents the concentration of the agent required to kill 50% of the insects, and LC90 represents the concentration of the agent required to kill 90% of the insects. Repeat the treatment for each group of tests 3 times and take the average value. The test results are shown in Table 1 below.

[0079] Table 1

[0080]

[0081]

[0082] As can be seen from Table 1 above, the aphid control effects of Comparative Examples 1 and 2 without adding Veratrum extract and Cnidium monnieri extract are slightly worse than those of Examples 1-3, indicating that the combination of Veratrum extract and Cnidium monnieri extract has a synergistic effect; in Comparative Examples 3, 4 and 7, no flue-cured tobacco or spirulina mud is added or spirulina is replaced with seaweed, and the aphid mortality rate is greatly reduced, and the pesticide concentration required for killing 50% and 90% of aphids is increased, which shows that the fermented flue-cured tobacco and spirulina have excellent aphid-killing effects; It can be seen from Comparative Examples 5 and 6 that Candida alcoholica has a better effect on the preparation of the pesticide of the present invention, the microorganisms and organic matter in the Spirulina mud promote fermentation and decomposition and assist flue-cured tobacco and Spirulina in releasing effective ingredients, and can also make the pesticide have a beneficial effect on the soil environment after being applied to the soil around the crops; Comparative Example 8 changed the fermentation method of the pesticide, stirring once a day for 20 consecutive days, which may lead to the invasion of foreign bacteria and affect the anaerobic fermentation process, and the quality of the prepared pesticide product is not as good as the pesticide products of Examples 1-3.

[0083] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for preparing a spirulina biopesticide, characterized in that: The method comprises the following steps: S1. Prepare water, spirulina mud, carbon source, and fermentation bacteria, and place them in 1m 3 in a sealed barrel; S2, open 1m per day 3 Stir once in a sealed barrel for 7-10 days, and add waste flue-cured tobacco when the mixed liquid is odorless and has a sour aroma; stir once every 7-10 days and stir 3-4 times; finally stir once every 15 days, stir twice and seal for 2-3 months to obtain fermentation liquid; S3. Add Veratrum extract and Cnidium monnieri extract to the fermentation liquid obtained in step S2, mix well, let stand for 1-3 hours, filter, and prepare Spirulina biopesticide.

2. The method for preparing the Spirulina biopesticide according to claim 1, characterized in that: The spirulina biopesticide comprises the following raw materials in parts by weight: 400-600 parts of water, 150-200 parts of spirulina mud, 50-100 parts of waste flue-cured tobacco, 20-30 parts of carbon source, 0.5-2 parts of fermentation bacteria, 1-20 parts of Veratrum extract and 1-20 parts of Cnidium monnieri extract.

3. The method for preparing the Spirulina biopesticide according to claim 1, characterized in that: The spirulina biopesticide comprises the following raw materials in parts by weight: 450-550 parts of water, 180-190 parts of spirulina mud, 60-80 parts of waste flue-cured tobacco, 22-38 parts of carbon source, 1-1.8 parts of fermentation bacteria, 5-10 parts of Veratrum extract and 5-10 parts of Cnidium monnieri extract.

4. The method for preparing the Spirulina biopesticide according to claim 1, characterized in that: The spirulina biopesticide comprises the following raw materials in parts by weight: 500 parts of water, 185 parts of spirulina mud, 70 parts of waste flue-cured tobacco, 25 parts of carbon source, 1.5 parts of fermentation bacteria, 8 parts of Veratrum extract and 8 parts of Cnidium monnieri extract.

5. The method for preparing the Spirulina biopesticide according to claim 1, characterized in that: The waste flue-cured tobacco is the crushed material of discarded dry flue-cured tobacco straw or tobacco leaves, and the crushed particle size is less than 1 cm.

6. The method for preparing the Spirulina biopesticide according to claim 1, characterized in that: The carbon source is one or more of white sugar powder, brown sugar powder and cassava flour.

7. The method for preparing the Spirulina biopesticide according to claim 1, characterized in that: The preparation method of the Veratrum extract is as follows: wash the Veratrum, dry it, crush it to 100-200 mesh, add water to extract it twice, the extraction time is 2-4h, the extraction temperature is 90-100℃, the solid-liquid ratio is 1:10-20, collect the extract, centrifuge it at a speed of 2000-3000r / min for 5-20min, remove the precipitate, collect the supernatant, and concentrate it under reduced pressure to obtain the Veratrum extract.

8. The method for preparing the Spirulina biopesticide according to claim 1, characterized in that: The preparation method of the Cnidium monnieri extract is as follows: wash the Cnidium monnieri, dry it, crush it to 100-200 meshes, extract it twice with 95% ethanol in a water bath with reflux, the solid-liquid ratio is 1:4-8, the extraction temperature is 50-70°C, the extraction time is 1-3h, collect the extract, let it stand, filter it, and concentrate it under reduced pressure to obtain the Cnidium monnieri extract.

9. The method for preparing the Spirulina biopesticide according to claim 1, characterized in that: The fermentation bacteria comprises the following raw materials in percentage by weight: 70-80% of Candida ethanolica, 10-15% of Pichia pastoris, and 10-15% of Bacillus amyloliquefaciens.

10. The method for using the Spirulina biopesticide according to claims 1-9, characterized in that: In the early and middle stages of crop growth, when aphids are infested, spray 20-50 ml of pesticide concentrate per mu of land with 4-6 times the volume of water on plant leaves, rhizomes and surrounding soil; in the middle and late stages of crop growth, when aphids are infested, spray 50-80 ml of insecticide per mu of land with 2-3 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, when aphids are infested, spray 30-70 ml of insecticide per mu of land with 4-6 times the volume of water on plant leaves, rhizomes and surrounding soil; in the early stages of mature crop growth, when aphids are infested, spray 70-100 ml of insecticide per mu of land with 2-3 times the volume of water on plant leaves, rhizomes and surrounding soil; the pesticide spraying time is after 6 pm every day.

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