Pesticide composition containing paecilomyces lilacinus and application in killing root-knot nematodes

Abstract

The present application relates to the technical field of pesticides, and provides a pesticide composition containing Paecilomyces lilacinus and application thereof in killing root-knot nematodes.The pesticide composition containing Paecilomyces lilacinus comprises fungus powder and modified chitosan in a mass ratio of 5:3-9:1, the modified chitosan is obtained by modifying chitosan with a phosphoric acid compound, and the fungus powder comprises Paecilomyces lilacinus, Trichoderma harzianum, Bacillus cereus and Bacillus polymyxa.Through the technical scheme, the problem of poor control effect of Paecilomyces lilacinus preparation on nematodes in the related art is solved.

Description

Technical Field

[0001] This invention relates to the field of pesticide technology, specifically to pesticide compositions containing Paecilomyces lilacinus and their application in killing root-knot nematodes. Background Technology

[0002] Nematodes are a type of lower animal, diverse in species and widely distributed, that parasitize plants, causing nematode diseases. Currently, the most effective biological pesticides for controlling nematodes include abamectin, Paecilomyces lilacinus, matrine, and actinomycetes. Paecilomyces lilacinus is the most widely used due to its rapid reproduction, strong vitality, and low toxicity; it can reduce the damage caused by root-knot nematodes in various crops, as well as cyst nematodes, stem nematodes, and other plant nematode diseases.

[0003] Currently, the most commonly used formulation of Paecilomyces lilacinus is granules. Its mechanism of action involves the mycelium of Paecilomyces lilacinus invading the nematode's body and eggs to reproduce, disrupting the nematode's physiological activities and leading to its death. However, the existing Paecilomyces lilacinus formulations on the market are not ideal in controlling nematodes. Summary of the Invention

[0004] This invention proposes a pesticide composition containing Paecilomyces lilacinus and its application in killing root-knot nematodes, solving the problem of poor control efficacy of Paecilomyces lilacinus preparations against nematodes in related technologies.

[0005] The technical solution of the present invention is as follows:

[0006] A pesticide composition containing Paecilomyces lilacinus includes a bacterial powder and modified chitosan in a mass ratio of 5:3 to 9:1, wherein the modified chitosan is obtained by modifying chitosan with a phosphate group compound, and the bacterial powder includes Paecilomyces lilacinus, Trichoderma harzianum, Bacillus cereus, and Bacillus polymyxa.

[0007] As a further technical solution, the mass ratio of Paecilomyces lilacinus, Trichoderma harzianum, Bacillus cereus, and Bacillus polymyxa is 15~20:5~10:2:8.

[0008] During the research process, the inventors conducted a systematic study on the mass ratio of the four bacterial powders and found that when the mass ratio of Paecilomyces lilacinus, Trichoderma harzianum, Bacillus cereus, and Bacillus polymyxa was 15~20:5~10:2:8, the pesticide composition containing Paecilomyces lilacinus had a better control effect on nematodes. Beyond this range, the control effect on nematodes decreased. Therefore, the mass ratio of the four was optimized to 15~20:5~10:2:8.

[0009] As a further technical solution, the raw materials for the modified chitosan include a phosphate compound and chitosan in a mass ratio of 0.5 to 3:10, preferably a phosphate compound and chitosan in a mass ratio of 1.5:10.

[0010] In this invention, the phosphate compound can be any one or more compounds containing phosphate groups in the art, such as acetyl phosphate, glycerophosphate, methylene diphosphate, fructose 1,6-bisphosphate, pyridoxal 5-phosphate, etc. The inventors discovered during the modification process that using a phosphate compound and chitosan in a mass ratio of 0.5 to 3:10 as raw materials resulted in better modification of chitosan, with the best modification effect observed at a mass ratio of 1.5:10. The resulting pesticide composition containing Paecilomyces lilacinus exhibited good control efficacy against nematodes.

[0011] As a further technical solution, the phosphate compound includes methylene diphosphate or fructose 1,6-bisphosphate.

[0012] As a further technical solution, the phosphate compound is fructose 1,6-bisphosphate.

[0013] The inventors discovered through research that when chitosan is modified with fructose 1,6-bisphosphate, the adsorption sites on the surface of the modified chitosan increase due to the presence of hydroxyl groups in fructose 1,6-bisphosphate, further enhancing the control effect of pesticide compositions containing Paecilomyces lilacinus on nematodes.

[0014] As a further technical solution, the preparation method of the modified chitosan includes the following steps: dissolving a phosphate compound in a solvent, adding chitosan for modification, and drying to obtain modified chitosan.

[0015] As a further technical solution, the modification temperature is 30~40℃, and the modification time is 5~10h.

[0016] As a further technical solution, the solvent is water.

[0017] In this invention, the solvent can be any one or more solvents that can dissolve phosphate-based compounds, preferably water.

[0018] The present invention also proposes a method for preparing the pesticide composition containing Paecilomyces lilacinus, comprising the following steps: mixing bacterial powder and modified chitosan to obtain a pesticide composition containing Paecilomyces lilacinus.

[0019] The present invention also proposes the application of the pesticide composition containing Paecilomyces lilacinus or the pesticide composition prepared by the preparation method described above in the killing of root-knot nematodes.

[0020] The working principle and beneficial effects of this invention are as follows:

[0021] 1. In this invention, the pesticide composition containing Paecilomyces lilacinus includes bacterial powder and modified chitosan. Modified chitosan is used as a carrier, and Paecilomyces lilacinus, Trichoderma harzianum, Bacillus cereus and Bacillus polymyxa are used in combination as bacterial powder. It can not only control root-knot nematodes of various crops, but also has the characteristics of being safe for humans, animals and the environment, high efficiency and long-lasting effect.

[0022] 2. In this invention, modified chitosan is used as a carrier. After the chitosan is modified by a phosphate compound, the phosphate groups in the phosphate compound carry a negative charge, which can combine with the positive charge of the amino groups in the chitosan. This reduces the antibacterial effect of the chitosan and increases the activity of the fungal powder when the chitosan is used in combination with the fungal powder, thereby improving the control effect of the pesticide composition containing Paecilomyces lilacinus on nematodes. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] The parameters of the raw materials in the following examples and comparative examples are as follows:

[0025] The active ingredient content of Paecilomyces lilacinus powder is 5 billion CFU / g;

[0026] The active ingredient content of Trichoderma harzianum powder is 2 billion CFU / g;

[0027] The effective substance content in Bacillus cereus is 5 billion CFU / g;

[0028] The effective substance content in Bacillus polymyxa is 2 billion CFU / g;

[0029] Chitosan: Deacetylation degree 90%, weight average molecular weight 200,000.

[0030] Example 1

[0031] S1. Dissolve 2.5g of methylene diphosphate in 80mL of water, add 50g of chitosan, modify at 30℃ and 400rpm for 10h, and dry to obtain modified chitosan.

[0032] S2. Mix Paecilomyces lilacinus powder, Trichoderma harzianum powder, Bacillus cereus powder and Bacillus polymyxa powder in a mass ratio of 15:5:2:8 to obtain the fungal powder.

[0033] S3. Mix the bacterial powder and modified chitosan at a mass ratio of 9:1 to obtain a pesticide composition containing Paecilomyces lilacinus.

[0034] Example 2

[0035] S1. Dissolve 2.5g of methylene diphosphate in 80mL of water, add 50g of chitosan, modify at 40℃ and 300rpm for 5h, and dry to obtain modified chitosan.

[0036] S2. Mix Paecilomyces lilacinus powder, Trichoderma harzianum powder, Bacillus cereus powder and Bacillus polymyxa powder in a mass ratio of 20:10:2:8 to obtain the fungal powder.

[0037] S3. Mix the bacterial powder and modified chitosan at a mass ratio of 5:3 to obtain a pesticide composition containing Paecilomyces lilacinus.

[0038] Example 3

[0039] The only difference from Example 1 is that: 7.5g of methylene diphosphate.

[0040] Example 4

[0041] The only difference from Example 1 is that: 15g of methylene diphosphate.

[0042] Example 5

[0043] The only difference from Example 3 is that methylene diphosphate is replaced with an equal amount of fructose 1,6-bisphosphate.

[0044] Comparative Example 1

[0045] S1. Mix Paecilomyces lilacinus powder, Trichoderma harzianum powder, Bacillus cereus powder and Bacillus polymyxa powder in a mass ratio of 15:5:2:8 to obtain the fungal powder.

[0046] S2. Mix the bacterial powder and chitosan at a mass ratio of 1:3 to obtain a pesticide composition containing Paecilomyces lilacinus.

[0047] Experimental Example 1

[0048] The mortality rates of root-knot nematodes were determined for the pesticide compositions obtained in Examples 1-5 and Comparative Example 1, respectively.

[0049] (1) After disinfecting and rinsing the root-knot nematode egg sacs of uniform size, they were cultured in the dark at 26°C for 7 days in a petri dish to obtain second-instar larvae of root-knot nematodes.

[0050] (2) Mix the pesticide composition and sterile water at a ratio of 1g:10mL, shake, and prepare a suspension;

[0051] (3) Dilute the second instar larvae of root-knot nematodes with sterile water to 100 larvae / mL to obtain a nematode suspension;

[0052] (4) Using a 12-well plate, add 1 mL of suspension and 1 mL of nematode suspension to each well. At the same time, use 1 mL of sterile water with 1 mL of nematode suspension as a control group. After incubating in the dark at 28℃ for 72 h, observe the number of dead root-knot nematodes and the total number of root-knot nematodes under a dissecting microscope at room temperature (the nematodes are considered dead when they are stiff and inactive when touched by the dissecting needle). Calculate the mortality rate according to the following formula:

[0053] Mortality rate = (Number of dead root-knot nematodes ÷ Total number of root-knot nematodes) × 100%;

[0054] Each treatment was set up with 5 replicates, and the average value was recorded as the final result, as shown in Table 1.

[0055] Table 1 Mortality rate of root-knot nematodes

[0056]

[0057] As shown in Table 1, compared with Comparative Example 1, the pesticide compositions containing Paecilomyces lilacinus obtained in Examples 1-5 had a mortality rate of over 91.4% against root-knot nematodes, indicating that the modification of chitosan with phosphate compounds improved the control effect of pesticide compositions containing Paecilomyces lilacinus against nematodes.

[0058] Experimental Example 2

[0059] Pot experiment:

[0060] (1) Mix the pesticide composition and sterile water at a ratio of 0.1g:10mL, shake, and prepare a suspension;

[0061] (2) Root-knot nematodes and soil were collected from a tomato greenhouse with severe root-knot nematode infestation in Wanggezhuang Experimental Field, Laoshan District, Qingdao City. The diseased roots were chopped up and mixed with the soil. The mixture was then placed in flower pots and transplanted with 4-leaf tomato seedlings, 3 seedlings per pot, in a triangular planting pattern. On the 3rd day after transplanting, 0.5g of pesticide composition per plant was applied around the plant. The control group was treated with 50mL of sterile water. The subsequent water and fertilizer management was carried out in accordance with the usual method.

[0062] (3) The soil root-knot nematode situation was investigated before and 60 days after treatment. The investigation method was as follows: 100g of rhizosphere soil was taken, and nematodes were separated using a modified Bellman funnel method. The nematode solution was collected and allowed to stand for 2 hours. Two-thirds of the supernatant was then aspirated, and boiling water at 100℃ was added to kill the nematodes. The nematodes were observed and counted under a microscope. The nematode population reduction rate and control effect were calculated according to the following formula:

[0063] Insect population reduction rate = (Number of insects before treatment - Number of insects after treatment) ÷ Number of insects before treatment × 100%;

[0064] Pest control effect = (Pest reduction rate in the treated group - Pest reduction rate in the control group) ÷ (1 - Pest reduction rate in the control group) × 100%;

[0065] Each treatment was set up with 5 replicates, and the average value was recorded as the final result, as shown in Table 2.

[0066] Table 2. Insect population reduction rate and insect control efficacy

[0067]

[0068] As can be seen from Table 2, compared with Comparative Example 1, the pesticide compositions containing Paecilomyces lilacinus obtained in Examples 1-5 have higher insect population reduction rates and insect population control effects, indicating that the modification of chitosan with phosphate compounds improves the control effect of pesticide compositions containing Paecilomyces lilacinus on nematodes.

[0069] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pesticide composition containing Paecilomyces lilacinus, characterized in that, The mixture comprises a bacterial powder and modified chitosan in a mass ratio of 5:3 to 9:

1. The modified chitosan is obtained by modifying chitosan with a phosphate-based compound. The bacterial powder includes Paecilomyces lilacinus, Trichoderma harzianum, Bacillus cereus, and Bacillus polymyxa. The raw materials for the modified chitosan include a phosphate-based compound and chitosan in a mass ratio of 0.5 to 3:

10. The preparation method of the modified chitosan includes the following steps: dissolving the phosphate-based compound in a solvent, adding chitosan for modification, and drying to obtain the modified chitosan.

2. The pesticide composition containing Paecilomyces lilacinus according to claim 1, characterized in that, The mass ratio of Paecilomyces lilacinus, Trichoderma harzianum, Bacillus cereus, and Bacillus polymyxa is 15~20:5~10:2:

8.

3. The pesticide composition containing Paecilomyces lilacinus according to claim 1, characterized in that, The phosphate compound includes methylene diphosphate or fructose 1,6-bisphosphate.

4. The pesticide composition containing Paecilomyces lilacinus according to claim 3, characterized in that, The phosphate compound is fructose 1,6-bisphosphate.

5. The pesticide composition containing Paecilomyces lilacinus according to claim 1, characterized in that, The modification temperature is 30~40℃, and the modification time is 5~10h.

6. The pesticide composition containing Paecilomyces lilacinus according to claim 1, characterized in that, The solvent is water.

7. The method for preparing a pesticide composition containing Paecilomyces lilacinus according to any one of claims 1 to 6, characterized in that, The process includes the following steps: mixing bacterial powder and modified chitosan to obtain a pesticide composition containing Paecilomyces lilacinus.

8. The application of the pesticide composition containing Paecilomyces lilacinus according to any one of claims 1 to 6 or the pesticide composition prepared by the preparation method according to claim 7 in the killing of root-knot nematodes.

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