Kunming scherzersonia sp. For preventing and treating root-knot nematode as well as compound fungicide and application of Kunming scherzersonia sp.

Abstract

The invention belongs to the field of microbial pesticides, and relates to a strain of Schelizersonia Kunming for preventing and treating root-knot nematode, and a compound bacterial agent and application of the Schelizersonia Kunming. The Kunming Zertimonas stutzeri strain NBNH-006 disclosed by the invention is preserved in the China Center for Type Culture Collection (CCTCC), and the preservation number of the Kunming Zertimonas stutzeri strain NBNH-006 is CCTCC NO: M20242323. Laboratory bioassay data shows that the Kunming Schmidtomonas stutzeri NBNH-006 has high poisoning activity on meloidogyne incognita, and has synergistic nematode killing activity after being compounded with the bacillus thuringiensis strain NBIN-863. Tomato pot experiment data shows that the control effect of the strain NBNH-006 on root-knot nematode is 67.49%, and the control effect is further improved to 84.38% after the strain NBNH-006 is compounded with bacillus thuringiensis NBIN-863. Therefore, the strain has a remarkable development value and a wide application prospect in agricultural production.

Description

Technical Field

[0001] The present invention belongs to the field of microbial pesticides, and relates to a Stutzeri monas kunmingensis for controlling root-knot nematodes, its compound microbial agent and application. Background Art

[0002] Due to the characteristics of the pathogen transmission being hidden, rapid reproduction, and long damage period, nematode diseases have become important diseases in modern agriculture in China. According to the estimation of the Food and Agriculture Organization of the United Nations (FAO), the loss of crop yield caused by nematode diseases can reach 12% - 20%. The pathogen of nematode diseases is plant parasitic nematodes, among which root-knot nematodes (Meloidogyne spp.) cause the most serious damage. The average annual loss of global yield directly or indirectly caused by root-knot nematodes is estimated to reach 173 billion US dollars.

[0003] Root-knot nematodes can parasitize almost all vascular plants. After the second-stage larvae of root-knot nematodes emerge from the eggs, they search for plant roots in the soil, use stylets and a series of secreted enzymes to damage the host root system and then drill into the plant body, establish feeding sites at appropriate positions, and induce the plant to form giant cells, resulting in the formation of root knots in the plant. Thus, it can be seen that the control window period of root-knot nematodes is very short, generally only two weeks, which also increases the difficulty of its control.

[0004] Currently, the main control means for nematodes is chemical control, but the application of a single chemical agent is likely to induce nematode resistance, and there are also problems of food and environmental safety hazards. Biological control is to use nematode natural enemies or biological natural products with nematocidal activity to control nematodes. Biological control has the characteristics of being environmentally friendly and pests being less likely to develop resistance, and has great potential to become a synergistic and alternative means to existing chemical control methods. With the proposal of the demand for green development of agriculture in China and the implementation of the action of reducing pesticides and fertilizers, biological control has gradually become an important research hotspot for the development of new green nematicides. Summary of the Invention

[0005] In view of the problem of limited biological control resources for nematodes, the primary object of the present invention is to provide a biocontrol bacterium for controlling root-knot nematodes. The strain is identified as Stutzeri monas kunmingensis, named Stutzeri monas kunmingensis NBNH-006, and the preservation number is: CCTCC NO: M20242323.

[0006] Another object of the present invention is the application of the above-mentioned Stutzeri monas kunmingensis and its compound microbial agent in the preparation of an agricultural nematicide for controlling root-knot nematodes.

[0007] In order to achieve the above object, the present invention takes the following technical measures:

[0008] The applicant collected the sediment at the bottom of the Dahei River in Hohhot, Inner Mongolia, isolated the bacteria in the sediment by the dilution plate coating method, and screened a strain with high toxicity against root-knot nematodes from the isolated strains through root-knot nematode bioassay, and named it NBNH-006. The single colony of strain NBNH-006 growing on Lauria-Bertani agar plate is light yellow, with irregular edges, wrinkled, moist and semi-transparent( Figure 1 ), and the cell morphology observed by microscopy is short rod-shaped, without endospores, and Gram staining is negative. Through the analysis of average nucleotide identity (ANI) comparison of the genome, it was found that the ANI similarity between this strain and the reference strain genome (GenBank accession number: GCA_021432085.1) of Stutzerimonas kunmingensis in the NCBI database (https: / / www.ncbi.nlm.nih.gov) is 97.06%, so NBNH-006 was identified as Stutzerimonas kunmingensis. This strain was sent to the China Center for Type Culture Collection for preservation on October 24, 2024. Classification name: Stutzerimonas kunmingensis NBNH-006; Preservation number: CCTCC NO: M20242323; Location: Wuhan University, Wuhan, China.

[0009] The protection scope of the present invention includes:

[0010] The fermentation broth of Stutzerimonas kunmingensis NBNH-006, and the fermentation broth contains viable bacteria of Stutzerimonas kunmingensis NBNH-006.

[0011] A compound, and the active ingredient of the compound includes Stutzerimonas kunmingensis with the preservation number of CCTCC NO: M20242323.

[0012] For the above-mentioned compound, preferably, the active ingredients of the compound include Stutzerimonas kunmingensis NBNH-006 and Bacillus thuringiensis NBIN-863. The preservation number of Stutzerimonas kunmingensis NBNH-006 is CCTCC NO: M20242323, and the preservation number of Bacillus thuringiensis NBIN-863 is CCTCC NO: M2013612, which has been disclosed in CN103898025B.

[0013] For the above-mentioned compound, preferably, the effective bacterial concentrations of Stutzerimonas kunmingensis NBNH-006 and Bacillus thuringiensis NBIN-863 are 1-10:1-10.

[0014] For the above-mentioned compound, preferably, the effective bacterial concentrations of the said Stenotrophomonas kunmingensis NBNH-006 and Bacillus thuringiensis NBIN-863 are 5:1 or 1:1.

[0015] Application of Stenotrophomonas kunmingensis NBNH-006, the fermentation broth of Stenotrophomonas kunmingensis NBNH-006 or its compound in controlling nematodes.

[0016] Application of Stenotrophomonas kunmingensis NBNH-006, the fermentation broth of Stenotrophomonas kunmingensis NBNH-006 or its compound in preparing nematode insecticides.

[0017] For the above-mentioned application, preferably, the said nematode is Meloidogyne incognita. Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0018] The present invention firstly screens out a strain of Stenotrophomonas kunmingensis NBNH-006 with high toxic activity against Meloidogyne incognita, and the compound with the known Bacillus thuringiensis strain NBIN-863 with high nematicidal activity can produce a synergistic effect.

[0019] In the tomato pot experiment, the pot control effect of the fermentation broth of strain NBNH-006 against Meloidogyne incognita is 67.49%, and the compound with Bacillus thuringiensis NBIN-863 can further increase the pot control effect to 84.38%, which is equivalent to the control effect of the commercially available nematicide abamectin· fosthiazate.

[0020] Previously, there has been no report on the application of Stenotrophomonas kunmingensis in the biological control field of root-knot nematodes. This invention can provide new resources for the creation of new microbial nematicides, lay a theoretical foundation for the development of green and efficient nematode control means, and has important economic value and application prospects for the production of organic high-quality agricultural products. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the colony morphology of strain NBNH-006 on Lauria-Bertani agar plate.

[0022] Figure 2 It is a schematic diagram of the effect of strain NBNH-006 on poisoning root-knot nematodes;

[0023] Among them: A shows the phenotype that the nematodes show body stiffness after being treated with the fermentation broth of strain NBNH-006 of the present invention for 10 h; B shows the phenotype that the nematodes are still alive after being treated with the control fermentation medium for 10 h. DETAILED DESCRIPTION OF THE INVENTION

[0024] To better explain the present invention, the main content of the present invention will be further clarified below in conjunction with specific embodiments. However, the content of the present invention is not limited to the following embodiments. The technical solutions described in the present invention are conventional technologies in the art unless otherwise specified. The reagents or materials are from commercial channels unless otherwise specified.

[0025] Example 1:

[0026] Isolation, screening and identification of Stenotrophomonas kunmingensis NBNH-006

[0027] 1) Isolation of strains: The applicant collected the bottom sludge in the Dahei River in Hohhot, Inner Mongolia, and isolated the bacteria in the sludge by the dilution plating method. The specific process was as follows: Weigh 1 g of the sludge sample and put it into a triangular flask containing 100 mL of Lauria-Bertani medium (formula: 10 g / L peptone, 5 g / L yeast extract, 10 g / L NaCl, 2% agar powder). After shaking and mixing evenly, take 1 mL of the suspension for gradient dilution. Take 0.2 mL of each dilution gradient and spread it on Lauria-Bertani agar (2% agar powder) plates, and culture overnight at 28 °C. Then pick single colonies respectively and transfer them to 5 mL of Lauria-Bertani liquid medium. After culturing at 28 °C and 220 rpm for 12 h, add an equal volume of 50% glycerol and store at -80 °C. A total of 12 kinds of bacteria were isolated.

[0028] 2) Screening of strains with high toxic activity against Meloidogyne incognita: The isolated bacteria were respectively inoculated into 5 mL of Lauria-Bertani liquid medium, activated overnight at 28 °C and 220 rpm, and then transferred to the fermentation medium (3% soybean meal, 1.5% corn steep liquor, 1.5% corn starch, pH 7.0 - 7.5) respectively. Culture at 28 °C and 220 rpm for 24 h. Calculate the bacterial cell concentration in each fermentation broth by the dilution counting method, and adjust the cell concentration in each fermentation broth to 1×10 6 CFU / mL and then set aside.

[0029] The Meloidogyne incognita used in the experiment was preserved and passaged by the applicant using potted tomatoes. Pick nematode egg masses from the roots of nematode-infected tomatoes, place the egg masses in a petri dish containing 15 mL of sterile water, incubate in the dark at 20 °C, observe the hatching of Meloidogyne incognita, collect the nematodes by centrifugation, and adjust the nematode concentration to 3 - 4 nematodes / μL. Take 100 μL of the fermentation broth of each bacterium into a 96-well plate, and then add 10 μL of the nematode suspension to each well. Ensure that 30 - 40 nematodes are added to each well by observing with an inverted microscope. Use the fermentation medium as a negative control, and each treatment group has 3 replicates.

[0030] After culturing the 96-well plates in the dark at 20 °C for 10 h, the mortality rate of nematodes in each treatment group was examined under a microscope. If the mortality rate in the control group was < 5%, the mortality rate did not need to be corrected. If the control mortality rate was between 5% and 20%, the mortality rate of the treatment group was corrected according to the formula: corrected mortality rate = (treatment group mortality rate - control group mortality rate) / (1 - control group mortality rate) × 100. If the control mortality rate > 20%, the experiment needed to be repeated.

[0031] Through bioassay with 96-well plates, the strain with the highest activity among the isolated bacteria was named NBNH-006, and the cell concentration of the fermentation broth was 1×10 6 CFU / mL, and the mortality rate of Meloidogyne incognita treated was 99.07% (±0.80%).

[0032] 3) Identification of strain NBNH-006: The single colony of strain NBNH-006 growing on Lauria-Bertani agar plate was light yellow, with irregular edges, wrinkled, moist, and semi-transparent ( Figure 1 ). Under microscopic examination, the cell morphology was short rod-shaped, without endospores, and Gram staining was negative. High-quality genomic DNA of strain NBNH-006 was extracted using the Qiagen genomic extraction kit. The genome of strain NBNH-006 was sequenced using the second-generation high-throughput sequencing technology combined with the third-generation Oxford Nanopore sequencing technology. The genome of strain NBNH-006 was analyzed and compared using the Average Nucleotide Identity (ANI) calculator, an online tool in EzBioCloud (https: / / www.ezbiocloud.net / ). The results showed that the ANI similarity between the genome of strain NBNH-006 and the reference strain genome of Stutzerimonas kunmingensis (GenBank accession number: GCA_021432085.1) was 97.06%. In taxonomy, when the ANI similarity between two strains is greater than 95%, the two strains are considered to be of the same species. Therefore, strain NBNH-006 was identified as Stutzerimonas kunmingensis.

[0033] The above strain was sent to the China Center for Type Culture Collection for preservation on October 24, 2024. Classification and naming: Stutzerimonas kunmingensis NBNH-006; Preservation number: CCTCC NO: M20242323; Location: Wuhan University, Wuhan, China.

[0034] Example 2:

[0035] Determination of the nematicidal activity of Stenotrophomonas kunmingensis NBNH-006

[0036] The fermentation broth of Stenotrophomonas kunmingensis NBNH-006 was prepared according to the fermentation culture method in Example 1, and the number of bacterial cells in the fermentation broth was adjusted to 1×10 6 CFU / mL with fresh medium as the stock solution (i.e., 1000 μL / mL in Table 1). The nematicidal activity of different gradients of NBNH-006 fermentation broth against Meloidogyne incognita was detected by the bioassay method of 96-well plates described in Example 1. The results are shown in Table 1. The killed nematodes showed a rigid phenotype, as Figure 2 shown. Using the SPSS v22.0 (IBM) data processing software, the probit model equation for the probability of NBNH-006 fermentation broth killing root-knot nematodes was obtained as PROBIT(P)= -3.617 + 1.999X (the variable X was transformed using the logarithm with base 10). By observing the confidence interval (shown in Table 2), the LC 50 value of NBNH-006 fermentation broth treating root-knot nematodes for 10 h was 64.54 μL / mL, and the 95% confidence interval was (54.12 μL / mL - 75.25 μL / mL), showing good nematicidal activity.

[0037] Table 1 Data for the determination of the nematicidal activity of the fermentation broth of Stenotrophomonas kunmingensis NBNH-006 against root-knot nematodes

[0038]

[0039] Table 2 Concentrations of NBNH-006 fermentation broth corresponding to different mortality probabilities of root-knot nematodes and 95% confidence intervals (partial)

[0040]

[0041] To facilitate subsequent detection of whether the strain NBNH-006 can be compounded with other nematicidal microbial agents, the known highly active strain Bacillus thuringiensis NBIN-863 (CCTCC NO: M2013612) was inoculated and prepared into a fermentation broth according to the fermentation culture method in Example 1. The LC 50 value of the fermentation broth of strain NBIN-863 treating root-knot nematodes for 10 h was 77.19 μL / mL, and the 95% confidence interval was (63.64 μL / mL - 91.37 μL / mL).

[0042] Example 3:

[0043] Determination of the nematicidal activity of the compound microbial agent of Stenotrophomonas kunmingensis NBNH-006 and Bacillus thuringiensis NBIN-863

[0044] To detect whether strain NBNH-006 can be compounded with other nematode-killing microbial agents, in this study, the fermentation broth of NBNH-006 was compounded with the fermentation broth of the known highly active strain Bacillus thuringiensis NBIN-863 (CCTCC NO: M2013612), and a 96-well plate bioassay was carried out. The number of bacterial cells in the fermentation broths of strain NBNH-006 and strain NBIN-863 was counted respectively, and the number of cells in the two fermentation broths was adjusted to the same amount (1×10 6 CFU / mL) by adding fresh medium. The two fermentation broths were mixed at a volume ratio of 1:1, and a compound microbial agent with a cell number ratio of 1:1 was obtained (the compound microbial agent at this concentration is 1000 μL / mL in Table 3). On the basis of preliminary tests, the compound microbial agent was diluted into gradient concentrations by adding fresh medium, and the toxicity of the compound microbial agent against root-knot nematodes was detected by 96-well plate bioassay. The bioassay results are shown in Table 3. Using the SPSS v22.0 (IBM) data processing software, the probit model equation for the probability of killing root-knot nematodes by the compound microbial agent with a cell number ratio of 1:1 was obtained as PROBIT(P) = -3.356 + 1.973X (the variable X was transformed using the logarithm with base 10). By observing the confidence interval (as shown in Table 4), the LC 50 value of the compound microbial agent with a cell number ratio of 1:1 against root-knot nematodes for 10 h was 50.16 μL / mL, and the 95% confidence interval was (40.95 μL / mL - 59.36 μL / mL).

[0045] Table 3 Toxicity determination data of the compound microbial agent (cell number 1:1) against root-knot nematodes

[0046]

[0047] Table 4 Concentrations of the compound microbial agent (cell number 1:1) corresponding to different mortality probabilities of root-knot nematodes and the 95% confidence interval (partial)

[0048]

[0049]

[0050] To evaluate the combined effect of the fermentation broth of NBNH-006 and the fermentation broth of NBIN-863, according to the main reference indexes for pesticide formula screening specified by the Institute for the Control of Agrochemicals, Ministry of Agriculture and Rural Affairs of China, the Sun Yunpei co-toxicity coefficient method was used to quantitatively analyze the co-toxic effect of the fermentation broth of NBNH-006 and the fermentation broth of NBIN-863 on root-knot nematodes. According to the LC 50 of the fermentation broth of NBNH-006 and the fermentation broth of NBIN-863 against root-knot nematodes for 10 h measured in Example 2 and the LC50 After calculating the relative toxicity indices separately, the co-toxicity coefficient is then calculated. The calculation formulas are as follows:

[0051] Relative toxicity index (TI) = Standard agent LC 50 / Test agent LC 50 × 100;

[0052] Measured toxicity index of the compound agent (ATI) = Standard agent LC 50 / Compound agent LC 50 × 100;

[0053] Theoretical toxicity index of the compound agent (TTI) = TI(A) × Percentage content of single agent A in the compound agent + TI(B) × Percentage content of single agent B in the compound agent;

[0054] Co-toxicity coefficient (CTC) = Measured toxicity index of the compound agent (ATI) / Theoretical toxicity index of the compound agent (TTI) × 100.

[0055] When the co-toxicity coefficient > 120, it is considered that the two single agents have a synergistic effect when compounded. When 80 ≤ co-toxicity coefficient ≤ 120, it is considered an additive effect. When the co-toxicity coefficient < 80, it is considered an antagonistic effect.

[0056] Taking the NBNH-006 fermentation broth as the standard agent, the calculated relative toxicity index TI values of the NBNH-006 fermentation broth and the NBIN-863 fermentation broth are 100 and 83.61 respectively. The measured toxicity index ATI of the compound agent (cell number ratio 1:1) is 128.67, and the theoretical toxicity index TTI of the compound agent is calculated as 91.81, thus calculating the co-toxicity coefficient CTC as 140.15. Since the co-toxicity coefficient > 120, the NBNH-006 fermentation broth and the NBIN-863 fermentation broth compounded at a bacterial cell number ratio of 1:1 have a significant synergistic effect.

[0057] According to the above experimental steps and calculation methods, the nematocidal activities of the compound agents of different ratios of the NBNH-006 fermentation broth and the NBIN-863 fermentation broth against root-knot nematodes and the co-toxicity coefficients of the compound agents were determined. The results are shown in Table 5. The results show that the compounding of the NBNH-006 fermentation broth and the NBIN-863 fermentation broth within the range of cell number ratios of 1 - 10:1 - 10 has a synergistic nematocidal effect. When the two fermentation broths are compounded at cell number ratios of 1:5, 1:10, and 10:1, the compound agents have an additive synergistic nematocidal effect. When the two fermentation broths are compounded at cell number ratios of 1:1 and 5:1, the compound agents have a synergistic nematocidal effect. Among them, the co-toxicity coefficient of the compound agent with a cell number ratio of 1:1 is the highest, indicating the strongest synergistic nematocidal effect.

[0058] Table 5 Co-toxicity Coefficient of the Compound Bacterial Agents of NBNH-006 and NBIN-863 with Different Cell Number Ratios against Root-knot Nematodes

[0059]

[0060]

[0061] Example 4:

[0062] Pot Experiment on the Control Effect of Stutzerimonas kunmingensis NBNH-006 and Its Compound Bacterial Agent against Root-knot Nematode Disease

[0063] To further evaluate the activity of Stutzerimonas kunmingensis NBNH-006 against root-knot nematodes, a pot experiment was conducted to detect the control effect of the fermentation broth of NBNH-006 against root-knot nematodes. Tomato was used as the host plant for nematodes in the pot experiment. Seeds of susceptible tomato (Jinpeng No. 3) were planted in seedling plug trays filled with sterilized seedling substrate and cultured in a greenhouse at a temperature of 25°C, a humidity of 60%, and a light / dark ratio of 16:8 for two weeks. Then the seedlings were transplanted into flower pots with a diameter of 14 cm, which were filled with sterilized sand-soil mixture (sand-soil volume ratio of 2:1). When transplanting, 3000 second-stage larvae of Meloidogyne incognita were inoculated at the roots of each seedling.

[0064] The fermentation broth of NBNH-006 prepared according to the fermentation and culture method in Example 1 was adjusted to a spore number of 10 8 CFU / mL level. One day after inoculating the nematodes, the seedlings were irrigated with the fermentation broth, and 50 mL of the fermentation broth was irrigated for each plant. Fresh fermentation medium was used as the blank control, and the commercially available nematicide abamectin· fosthiazate (total active ingredient content 10%, abamectin content 2.5%, fosthiazate content 7.5%) was used as the positive control. The dosage of the positive control was diluted according to the dosage indicated in the instruction manual. In addition, it was found in Example 3 that the compound of the fermentation broth of NBNH-006 and the fermentation broth of NBIN-863 at a cell number ratio of 1:1 had the highest synergistic nematicidal activity. Therefore, in this example, the control effect of the NBNH-006 / NBIN-863 compound bacterial agent at this ratio against root-knot nematodes in pots was also tested.

[0065] There were a total of 5 treatment groups (the treatment group irrigated with the fermentation broth of NBNH-006, the treatment group irrigated with the fermentation broth of NBIN-863, the treatment group irrigated with the NBNH-006 / NBIN-863 compound bacterial agent (cell number ratio 1:1), the treatment group irrigated with chemical agents, and the treatment group irrigated with fresh fermentation medium), and each treatment group had 5 replicates.

[0066] Place the potted plants after root irrigation in the greenhouse and water them once every two days. 30 days after root irrigation, carefully pull up the tomatoes with their roots and wash them with water to remove the substrate soil. Count the number of root knots on each plant, weigh the weight of the tomato roots with a balance, and calculate the number of root knots per gram of roots on average to represent the infection situation of root-knot nematodes.

[0067] Calculate the relative control efficacy of the treated samples against root-knot nematodes according to the formula: Control efficacy = (Number of root knots per gram of roots in the negative control - Number of root knots per gram of roots in the treatment group) / (Number of root knots per gram of roots in the negative control) * 100.

[0068] The results are shown in Table 6. Under potted conditions, the average number of root knots per gram of roots of the plants treated with the fermentation broth of Stutzerimonas kunmingensis NBNH-006 by root irrigation was 89.99 ± 12.92, and the relative control efficacy was 67.49%. While for the plants treated with the compound microbial agent prepared by mixing the fermentation broth of Bacillus thuringiensis N BIN-863 with the fermentation broth of Stutzerimonas kunmingensis NBNH-006 at a cell number ratio of 1:1 by root irrigation, the average number of root knots per gram of roots was 43.24 ± 10.37, and the relative control efficacy was 84.38%, which was comparable to that of the commercially available chemical nematicide. The results indicate that Stutzerimonas kunmingensis NBNH-006 and its compound microbial agent have good control efficacy against root-knot nematodes under potted conditions and have significant development value.

[0069] Table 6 Potted control efficacy of the fermentation broth of Stutzerimonas kunmingensis NBNH-006 and its compound microbial agent against root-knot nematodes

[0070]

[0071] Different lowercase letters after the data in the same column indicate significant differences at the 5% level.

Claims

1. An isolated strain of Stitzerella kunmingensis ( Stutzerimonas kunmingensis )NBNH-006, the deposit number of the strain is: CCTCC NO: M20242323.

2. The fermentation broth of Kunming Stitzerella NBNH-006 according to claim 1, wherein the fermentation broth contains live bacteria of Kunming Stitzerella NBNH-006.

3. A compound, wherein the active ingredient of the compound includes Kunming Stitzermonas with a deposit number of CCTCC NO: M20242323.

4. The composition according to claim 3, wherein the active ingredients of the composition include Kunming Stitzermonas NBNH-006 and Bacillus thuringiensis NBIN-863, the deposit number of Kunming Stitzermonas NBNH-006 is CCTCC NO: M20242323, and the deposit number of Bacillus thuringiensis NBIN-863 is CCTCC NO: M2013612.

5. The composite according to claim 4, wherein the effective bacterial concentration of the Kunming Stitzerella NBNH-006 and the Bacillus thuringiensis NBIN-863 is 1-10:1-10.

6. The compound according to claim 5, wherein the effective bacterial concentration of Bacillus thuringiensis NBNH-006 and Bacillus thuringiensis NBIN-863 is 5:1 or 1:

1.

7. Use of the Kunming Stitzerella NBNH-006 described in claim 1, the fermentation liquid of Kunming Stitzerella NBNH-006 described in claim 2, or the compound described in claim 3 in controlling nematodes.

8. Use of the Kunming Stitzerella NBNH-006 described in claim 1, the fermentation liquid of Kunming Stitzerella NBNH-006 described in claim 2, or the composite product described in claim 3 in the preparation of nematode insecticides.

9. The use according to claim 7 or 8, wherein the nematode is Meloidogyne incognita ( Meloidogyne Incognita ).

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