CN114752506A - Bacterial strain for controlling underground pests and application thereof - Google Patents

Abstract

The application discloses a bacterial strain for controlling underground pests and application thereof. The bacterial strain for preventing and controlling the underground pests is green muscardine fungus QJMr101 with the preservation number of CGMCC No. 22423. The bacterial strain and the microbial preparation thereof have a killing effect on cutworms, black cutworms and wireworms, and can effectively prevent and reduce the occurrence of underground pests. In addition, the microbial preparation has a promoting effect on the growth of crops such as tobacco seedlings and the like, and has the effect of preventing dead seedlings from dying.

Description

Bacterial strain for controlling underground pests and application thereof

Technical Field

The application relates to the technical field of biological control of underground pests, in particular to a bacterial strain for controlling the underground pests and application thereof.

Background

The underground pests refer to pests living in soil and damaging roots, stems close to soil surface and other parts of plants, and mainly comprise mole cricket, grub, cutworm, wireworm, maggot and the like. The pests have various types and harm hosts. For example, eating the underground tissue of the seedling, such as the young root, the subterranean stem, etc., of the seedling, so that the seedling cannot come out of the soil or the whole seedling withers; underground pests such as cutworms and the like also mainly eat roots, stems, root tubers, seedlings, growing points and the like of crops, and often cause seedling shortage, ridge breaking or poor plant growth. Is a great problem in the crop planting industry which is seriously harmed.

At present, the control of underground pests is mainly based on chemical agents, such as chlorpyrifos, phoxim and the like, which can quickly and effectively kill grubs. Although the pesticide has the advantage of good quick action, the long-term use of the pesticide has the following hazards or hidden dangers: firstly, the pesticide has killing effect on beneficial birds such as natural enemies of pests and pollinating insects while killing and poisoning the pests, and can destroy the ecological balance of the natural world in the long run. Secondly, a great amount of chemical pesticide is used, so that the pesticide is gradually accumulated in the environment, particularly in soil, and the problem of pesticide pollution to the environment is caused. Thirdly, the pesticide is absorbed by crops, enters the bodies of animals, and is subjected to biological enrichment and concentration to enable the pesticide to have higher toxicity, so that not only are natural enemies of pests more susceptible to toxic action, but also human health is threatened through a food chain; pesticide residues also directly affect food safety and the production and trade of crops; fourthly, the chemical pesticide is used in large quantities for a long time, so that the pests are easy to generate extremely strong resistance, the pest control effect is influenced, and the pest control system can fall into a vicious circle that the dosage of the chemical pesticide is continuously increased. Currently, prevention of pesticide contamination has become a concern in many countries of the world today, and chemical pesticide abuse can create more serious and profound damage than insect damage.

In order to reduce the use of chemical pesticides, related studies have shown that microorganisms can be used for biological control of pests; however, the existing biocontrol agents capable of conveniently and effectively killing various underground pests are quite lacking. The vigorous development and development of microbial pesticides, particularly biocontrol agents based on filamentous fungi, is imperative and is an effective way to solve the problem of 3R (namely resistance, rampant and residue) of chemical pesticides.

Disclosure of Invention

The purpose of the application is to provide a novel strain for underground pest control and application thereof.

The following technical scheme is adopted in the application:

one aspect of the application discloses a bacterial strain for controlling underground pests, which is green muscardine fungus QJMr101 with the preservation number of CGMCC No. 22423.

It should be noted that, the present application isolated a fungal strain from muscardine cutworm, namely Metarhizium rileyi (Metarhizium rileyii), labeled as Metarhizium rileyi QJMr 101; the method has the advantages of high liquid-solid two-phase fermentation production efficiency and large spore yield, the content of conidium can reach 150 plus one hundred million/g, and the method has strong infection activity on various underground pests such as cutworms, black cutworms, wireworms and the like. Therefore, the bacterial strain is preserved and used for preparing the microbial preparation for controlling the soil insects, and the soil insects in the plant root growth process can be effectively controlled by adopting the bacterial strain or the microbial preparation prepared by the bacterial strain.

It should be noted that the inventors of the present application isolated three strains of soil pest control fungi with different functions from the microbial flora of cutworm, identified the three strains of fungi by morphological and molecular biology respectively, and determined that the three strains of fungi are metarhizium anisopliae QJMa143, beauveria bassiana QJBb181 and metarhizium leiocarpum QJMr101 respectively. The application mainly protects the metarhizium laevigatum QJMr101, and other two fungus strains are protected in other patent applications respectively.

In another aspect of the present application, the use of the strain of the present application for the preparation of a microbial formulation for subterranean pest control is disclosed.

In yet another aspect of the present application, a microbial formulation for subterranean pest control is disclosed, the microbial formulation comprising a metarhizium lepigone QJMr101 and/or a metarhizium lepigone QJMr101 active substance.

In one implementation of the present application, the metarhizium laevis QJMr101 active substance is a conidium and/or microsclerotia fermentation product of metarhizium laevis QJMr 101.

It is understood that the metarhizium lebbeck QJMr101 active substance refers to a substance having the same action as the metarhizium lebbeck QJMr101 after administration, such as conidia, microsclerotia fermentation product, and the like.

In one implementation of the present application, the microbial preparation of the present application further comprises a fermentation substrate.

In addition, the main insecticidal active ingredients of the microbial preparation are the metarhizium laevis QJMr101 and/or the metarhizium laevis QJMr101 active substances; however, for better insecticidal effect, the microbial preparation of the present application contains not only the insecticidal active ingredient but also other nutritional ingredients, such as fermentation substrate; on one hand, the bait plays a role in trapping and killing underground pests; on the other hand, the fungal hyphae can also be planted and symbiotic in roots of crops such as tobacco, so that the yield and quality of the crops are improved, and the economic benefit of the crops is improved. In an implementation of the application, the microbial preparation is adopted for disinsection, and can also promote the growth of tobacco seedlings and increase the yield.

In one implementation of the present application, the fermentation substrate is at least one of corn starch, wheat bran, and rice flour.

In one implementation manner of the application, the mass ratio of the metarhizium laevis QJMr101 and/or the metarhizium laevis QJMr101 active substance to the fermentation substrate in the microbial preparation is 1: 100-200.

It is noted that, although, the microbial formulations of the present application may be used for a variety of subterranean pest control; however, it is not excluded that the microbial preparation of the present application can also be used in combination with other biological or chemical drugs as long as the pesticidal activity of the microbial preparation itself is not affected. In addition, the microbial preparation of the present application may also be prepared into various dosage forms according to product requirements, such as wettable powder, powder or granules, as long as corresponding auxiliary components are added, and is not specifically limited herein.

In a further aspect, the application discloses the use of a microbial preparation of the application in the preparation of a formulation for promoting tobacco seedling growth.

In a further aspect, the application discloses the use of the microbial preparation of the application in the preparation of a preparation for preventing death of tobacco seedlings.

The research of the application finds that the microbial preparation can kill various underground pests, promote the growth of tobacco seedlings and prevent dead seedlings from dying; therefore, the microbial preparation can be prepared into a preparation for promoting the growth of tobacco seedlings or a preparation for preventing the death of the tobacco seedlings.

In another aspect, the application discloses a method for controlling underground pests, which comprises the steps of mixing the bacterial strain or the microbial preparation with an organic fertilizer or fine soil to prepare a mixture, and applying the mixture to crops at the bottom of a upturned soil breaking period or a ridging period before transplanting to play a role in controlling the underground pests.

In one implementation of the present application, the weight ratio of the bacterial strain or microbial preparation of the mixture to the organic fertilizer or fine soil is 1: 10.

The beneficial effect of this application lies in:

the bacterial strain and the microbial preparation thereof have a killing effect on cutworms, black cutworms and wireworms, and can effectively prevent and reduce the occurrence of underground pests. In addition, the microbial preparation has a promoting effect on the growth of crops such as tobacco seedlings and the like, and has the effect of preventing dead seedlings from dying.

Drawings

FIG. 1 is a graph showing microscopic observation results of a spore and a spore of Metarrhizium flexuosum QJMr101 in the present example.

The metarhizium laevis QJMr101 is preserved in China General Microbiological Culture Collection Center (CGMCC) at 2021, 05 and 17 months, and the preservation number is as follows: CGMCC No. 22423.

Detailed Description

The present application will be described in further detail with reference to specific examples. The following examples are merely illustrative of the present application and should not be construed as limiting the present application.

Examples

Separation of high-efficiency infection strain of underground pests

The spore powder on the surface of the stiff insects was dipped with an inoculating needle under sterile conditions and streaked onto 1/4SDAY plate medium 90mm in diameter, or the stiff insects were gently and quickly shaken on the medium with sterilized forceps. The plate was placed in a 26 ℃ incubator and cultured in the dark. After 3 days, the colony edge hyphal tips on the picking medium were transferred to a new 90mm 1/4SDAY plate medium. Repeating the operation for 2-3 times to obtain the purified beauveria bassiana strain. The purified strain was cultured in the dark in a constant temperature incubator at 26 ℃ for 2 weeks, and short-term storage and long-term storage of 20% glycerol were performed, respectively.

Secondly, identifying the high-efficiency infection strain of underground pests

1. Morphology identification method

In this example, the QJMr101 strain was observed for colony morphology and sporulation in pure culture. Specifically, conidia of the QJMr101 strain are inoculated into an SMPY liquid culture medium and shake-cultured for 72 hours at the temperature of 26-28 ℃ and the speed of 150 rpm. The colony diameter was measured after 7 days of dark culture on SMPY solid medium plates. Embedding a sterilized cover glass with the size of 5 multiplied by 5mm into the edge of the bacterial colony, continuously culturing for a week under the same condition, taking down the cover glass for flaking, carrying out microscopic examination, observing the shapes of mycelium, conidiophores and conidia of the bacterial strain to be detected, and determining the size of the bacterial strain.

The result of the identification of the biological morphological characteristics is as follows:

(1) colony characteristics: on SMAY culture medium, the colony is initially white and hairy, gray green to olive green when producing spore, and a clump of green conidium pile grows from the center of the colony from inside to outside. Conidiophores are unigenic or aggregated or closely arranged, branched or rotasomal. The colonies of the late culture were shell-like. The diameter of 7d bacterial colony of the strain can be 2.5-3.0 cm on SMPY at 25 ℃ under the condition of scattered light.

(2) Morphological characteristics: the hyphae have branch separation and are 1.4-2.1 μm thick. The size of the phialide type spore-forming cells is 2.1-2.9 multiplied by 7.1-7.5 mu m; producing a conidiophore chain mature into a basal plane from the apical end of the phialide; the inclination of the connecting point of the spore chain is small; conidium single cells are pear-shaped to ellipse, one end of each conidium single cell is sharpened, and the diameter is 3.3-4.6 microns multiplied by 2.9-3.6 microns. Conidiophores are clustered and sometimes singly grow at the end of short clustered sporophores. The species of the strain producing the sporophytes and conidiophores are shown in figure 1.

2. Molecular characterization of ITS sequences of strains

The molecular identification adopts a benzyl chloride method to extract the total DNA of QJMr101 strain, adopts ITS universal primers of fungi to perform ITS 1-5.8S rDNA-ITS 2 sequence PCR amplification, sequences the amplified product, performs Blast comparison on the sequencing result and known sequences in NCBI database, searches for the same species with homology higher than 98% and E value of 0.0.

In this example, sequencing was performed by Shanghai Bio Inc. Sequencing results show that the total length of ITS 1-5.8S rDNA-ITS 2 sequences of QJMr101 strain is 550bp, wherein the 5' end comprises partial 18S rRNA gene sequences: the 1-49 bp is partial 18S rRNA gene sequence. The 3' end comprises a partial 28S rRNA gene sequence: 520-550bp is the partial 28S rRNA gene sequence. The rest are ITS zones: the 50-195 bp is the ITS1 region complete sequence, the 196-342bp is the 5.8S rRNA gene complete sequence, and the 343-550 bp is the ITS2 region complete sequence.

In conclusion, the strain QJMr101 is white in the early stage of the bacterial colony on the SMAY culture medium, purple brown pigment can be seen on the back, the late-stage spore production is bright green, and the characteristics of the strain QJMr101 such as conidium conglomeration and accumulation are obviously different from the characteristics of the similar species Metarhizium flavoviride (Metarhizium flavoviride) subsphaeroides or broad fusiform conidia; the difference of the Metarhizium anisopliae (Metarhizium anisopliae) with conidia larger than 10 mu m is that the Metarhizium anisopliae has smaller spores, and most of the Metarhizium anisopliae are elliptic to nearly cylindrical. Furthermore, metarhizium anisopliae has a wide range of insect hosts, and the metarhizium anisopliae mainly intensively infects Lepidoptera Spodoptera larvae. The QJMr101 strain is identified to be the Metarhizium rileyii of the Metarhizium leiocarpum by integrating the culture characteristics and morphological characteristics and the results of ITS1-5.8-ITS2 rDNA molecular clone sequencing comparison, and is marked to be the Metarhizium rileyii of the Metarhizium rileyi.

Determination of insecticidal activity of Metarrhizium Laevigatum QJMr101

In this example, the insecticidal activity of the obtained metarhizium laevis QJMr101 was measured as follows:

collecting mature conidia of Metarrhizium rillii QJMr101 strain, culturing at 28 deg.C on SMAY medium for 14 days, and preparing into 1 × 10 with 0.5% Tween-80 sterile water⁷Using a micro dropper to perform dropping treatment on the cutworm larvae of 3 ages with each 20 mu L spore suspension per mL, setting 3 treatments, and repeating 10 test worms per head. After inoculation, the strain is raised at the room temperature of 25 ℃ and the humidity of 50-60%, and a non-inoculated 0.5% Tween 80 solution is used as a blank control. Every 24h, 1 mortality was checked and 12d of continuous observation recorded the number of dead insects.

Indoor bioassay shows that: the green muscardine strain QJMr101 has strong toxicity to cutworm larvae, the cumulative corrected mortality rate reaches 92.6%, and LT50 obtained by a quantitative value analysis method is 5.25 d.

Microsclerotium liquid fermentation of good strain of Metarrhizium Laevigatum

1. Preparation of plate strain (90mm dish)

The strain of the green muscardine fungus QJMr101 is streaked and inoculated on a SMAY culture medium, each batch is transferred to 3-6 dishes, and the dishes are placed in an incubator at 25 +/-1 ℃ for culturing for 10 days under the light. The activated green muscardine lai QJMr101 plate strain is placed in a refrigerator at 4 ℃ for short-term storage for liquid shake flask inoculation.

2. Preparation of mother fungus Strain (1L triangular flask)

Inoculating the inoculation amount of the mother solution into 1/4SDA liquid culture medium, or directly placing 6-8 fungus cakes (with the diameter of 8mm) into 1/4SDA culture solution under the aseptic condition by adopting a puncher; shaking culture was performed at 25 ℃. + -. 2 ℃ at 250rpm for 2 d. Washing conidia of Metarrhizium anisopliae from spore-producing plate with sterilized 0.1% Tween 80 water solution, and collecting spore suspension by hemocytometerAdjusted to 1X 10⁸spores/mL. The culture conditions of the shake flask fermentation broth were visually observed. And (3) detecting a normal triangular flask of liquid strain, transferring and sterilizing the liquid strain in a liquid fermentation tank of 1/4SDA fermentation liquor for 30L.

3. Pilot liquid fermentation (Microsclerotium induction fermentation)

The spore suspension cultured in shake flask for 2d was aseptically inoculated in a ratio of 5% into a 24L liquid fermentor (30L). Fermentation process parameters: temperature: 26-28 ℃; ventilation volume: 800L/h; dissolved oxygen (%): 10-100%; fermentation rotating speed: 150rpm at the early stage (3d) and 200rpm at the later stage (3 d); initial pH6.5; when the pH value is continuously lower than pH4.5 after fermentation for about 3 days, the formation of microsclerotia is induced. And (3) fermentation period: and 6d, measuring the yield of the microsclerotia in the fermentation liquor after the end. Drying and harvesting of microsclerotia: and (3) mixing and uniformly mixing the fermentation product of the microbial sclerotium according to the proportion of the fermentation liquid to the filling material which is 1: 1-3. Air-drying at 35 deg.C for 48 hr, sieving, and collecting 150-micron microsclerotia granules with diameter of 2-2.5 × 10⁷And (4) sampling and measuring the drying loss of the cells/mL, and storing the cells at room temperature for later use when the drying loss is less than 5%.

Liquid-solid two-phase fermentation of spore powder of green muscardine fungus strain (spore powder production)

The metarhizium rebaudiana strain QJMr101 is inoculated on a solid SMAY culture medium and cultured in a constant temperature incubator at 26 ℃ for 2 weeks in the dark. Respectively scraping mature conidia under aseptic condition, and preparing into 1 × 10 in 0.1% Tween 80 sterile water⁸～1×10⁹And inoculating 20mL of spore/mL suspension into 200mL of 1/4SDY liquid culture solution in a 1L triangular flask, maintaining the temperature at 25-27 ℃ and the rotation speed at 100-200 rpm, and performing shaking culture for 72h to obtain liquid seed solution.

The solid phase fermentation material is rice, the rice is uniformly soaked according to the weight ratio of 2:1 of the rice to water, the soaked rice is filled into a 50 x 40 polyethylene fermentation bag according to the filling amount of 300g per bag after being soaked for 2 hours, the opening of the ventilation bag is tightly tied by a thread rope, the bag is filled into a sterilization pot, and the sterilization is carried out for 30min at the temperature of 121 ℃. Naturally cooling on a superclean workbench, and then cooling according to the proportion of 1: inoculating liquid mother bacteria at an inoculation ratio of 10 (V/W). Uniformly mixing, placing the mixture on a culture shelf at 25-27 ℃, culturing for 12-15 days by illumination, collecting the culture by using a cloth bag, and ventilating and drying. And collecting spore powder by using a 100-mesh shaking screen. The collected conidium powder is weighed, and the yield of the QJMr101 strain is 1.5-2.0%. And counting by using a blood counting plate, wherein the number of live spores of the green muscardine fungus QJMr101 strain per gram of spore powder is 300 hundred million/g, and the heating decrement is 5-8%.

Preparation of bio-control microbial preparation of green muscardine fungus

The dry spore powder of the fermented green muscardine fungus QJMr101 strain and the fermentation substrate are crushed together and then added with auxiliary materials, or the microbial core fermented in one step is added with diatomite according to the ratio of 1:3(V/W) to prepare the fungus powder with the effective content of more than or equal to 10 hundred million spores/g.

The microbial preparation may be prepared into various dosage forms, such as powder, wettable powder, granule, etc., as long as corresponding auxiliary components are added, and is not limited specifically.

Field test for preventing and treating tobacco field wireworms by using green muscardine fungus biocontrol agent

1. Materials and methods

Test agents: metarhizium lebelii powder, and local conventional treating agent. The soil insects are golden insects.

Experiment design: 15 cells of 10 x 10m are randomly selected, each cell is spaced by more than 2m, so that mutual interference among the cells is prevented, and the cultivation management conditions among all the test cells are basically kept consistent. Selecting a tobacco curing field where the tobacco wireworms occur all the year round, setting 5 treatments for the experiment, repeating the treatment for 3 times and 15 cells in total, uniformly mixing the green muscardine fungus powder and clear water with fertilizers in the tobacco field from the valve crushing period to the ridging period, and then broadcasting, wherein local conventional treatment agents are synchronously applied with rooting water in the transplanting link.

Processing one: 1 kg/mu of green muscardine fungus powder;

and (5) processing: 2.5 kg/mu of Metarrhizium Laevigatum powder;

and (3) treatment III: 5kg of green muscardine fungus powder per mu;

and (4) treatment: the drug control CK1, in this example chlorpyrifos is used as the drug control, and the dosage is 2.7 kg/mu;

and (5) processing: blank control CK2, rice flour control, i.e., equal amount of rice flour was used in place of Metarhizium leprae.

Test investigation: investigating the tobacco seedlings once in 3 days, 5 days and 10 days after transplanting, investigating the number of the broken seedlings, the number of the damaged plants and the insect quantity in each cell for three times, and calculating the damaged plant rate and the control effect according to the formula (1) and the formula (2). Meanwhile, according to the tobacco seedling pest damage symptom and the field pest investigation condition, the number of the pest plants and the pest species are recorded.

Formula (1):

formula (2):

2. results and analysis

The investigation statistical results of the damage conditions of underground pests 3 days, 5 days and 10 days after the tobacco seedlings are transplanted in different using amount treatment areas, conventional agent treatment areas and control areas of the metarhizium reinhardtii powder are shown in table 2. The investigation result shows that the underground pests in the test area are the wireworms. 3 days after the tobacco seedlings in the clear water control area are transplanted, a large number of seedling breakage and tobacco plant damage conditions occur, 10 days after the transplantation, the seedling breakage rate of the blank control area reaches 7.55%, and the damaged plant rate is 11.43%.

The damage of the underground pests after the conventional medicament treatment is obviously lighter than that of the blank control area, and no obvious aggravation trend is generated over time. After 10 days of transplanting, the maximum seedling breaking rate of 1.59 percent and the damaged plant rate of 3.04 percent are both obviously lower than that of a blank control (P is 0.01), and the final control effect reaches 81.08 percent.

After different dosages of the green muscardine fungus powder are treated, the damage degree of underground pests is obviously lower than that of a blank control area, the seedling breaking rate is only 1.11-1.59% after 10 days of transplantation, the damaged rate is 1.87-3.04%, the damage rate is obviously lower than that of a control (P is 0.01), wherein the control effect of 5 kg/mu of green muscardine fungus granules on the underground pests is shown, and the control effects of 3 days and 5 days after transplantation are 71.17% and 73.48.00% respectively; the final control effect, namely the control effect of the 2.5 kg/mu and 5 kg/mu metarhizium retrenbergii granules on the soil insects is better 10 days after transplantation, wherein the control effect is 83.65 percent and 80.00 percent respectively, and is equivalent to the control effect of the conventional medicament treatment (P is 0.01).

TABLE 2 Green prevention and control of green Laiwei Metarrhizium anisopliae underground pest effect investigation statistical table (Yunnan Qujing)

Note: the values listed in the table are mean ± sem (n ═ 172). The data were statistically analyzed by Student Newman Keuls (S-N-K) and the difference between the lower case letters and the upper case letters was significant at 0.05 and 0.01.

Test results show that in severe underground pest occurrence areas, the underground pests can be effectively prevented and controlled by conventional pesticide treatment and 1 kg/mu, 2.5 kg/mu and 5 kg/mu of Metarrhizium limacinum treatment, and the seedling breakage rate and the damaged plant rate are reduced. But the conventional medicament treatment can not effectively reduce the field pest plant rate and the quantity of the hundreds of plants, and the medicament treatment only kills underground pests after the transplantation to reduce the field seedling breakage rate and the damaged plant rate. The treatment during the soil crushing period or ridging period of the green muscardine fungi can effectively reduce the pest rate and the pest amount of the field, and the control effect on underground pests is good in the former period, wherein 2.5 kg/mu and 5 kg/mu of green muscardine fungi powder or powder treatment has the best control effect on the underground pests, the final control effect can reach 80.00%, the control effect is equivalent to that of the conventional medicament treatment, no adverse effect is caused on the growth of tobacco seedlings, and the green muscardine fungi powder or powder treatment has an obvious effect of promoting the growth of the tobacco seedlings. Therefore, the green prevention and control of the soil insects is carried out by applying the green muscardine fungus powder in a strip mode in a valve breaking period or a ridging period, and the recommended dosage is 2.5 kg/mu.

The foregoing is a more detailed description of the present application in connection with specific embodiments thereof, and it is not intended to limit the present application to the details thereof. It will be apparent to those skilled in the art from this disclosure that many more simple derivations or substitutions can be made without departing from the spirit of the disclosure.

Claims (10)

1. A strain for subterranean pest control characterized by: the strain is Metarrhizium Lawsonii QJMr101 with the preservation number of CGMCC No. 22423.

2. Use of the strain according to claim 1 for the preparation of a microbial formulation for subterranean pest control.

3. A microbial formulation for subterranean pest control characterized by: the microbial preparation comprises a metarhizium lebbeck QJMr101 and/or a metarhizium lebbeck QJMr101 active substance.

4. The microbial preparation of claim 3, wherein: the metarhizium lebbeck QJMr101 active substance is conidium and/or microsclerotia fermentation product of the metarhizium lebbeck QJMr 101.

5. The microbial preparation of claim 3 or 4, wherein: the microbial preparation also includes a fermentation substrate.

6. The microbial formulation of claim 5, wherein: the fermentation substrate is at least one of corn starch, wheat bran and rice flour.

7. The microbial formulation of claim 6, wherein: the mass ratio of the metarhizium laevigatum QJMr101 and/or the metarhizium laevigatum QJMr101 active substances to the fermentation substrate in the microbial preparation is 1: 100-200.

8. Use of a microbial preparation according to any one of claims 3 to 7 in the manufacture of a preparation for promoting tobacco seedling growth.

9. Use of a microbial preparation according to any one of claims 3 to 7 in the preparation of a preparation for the prevention of tobacco seedling death.

10. A method for controlling underground pests, which is characterized by comprising the following steps: the strain of claim 1 or the microbial preparation of any one of claims 3 to 7 is mixed with organic fertilizer or fine soil to prepare a mixture, and the mixture is applied to crops at the bottom of a upturned soil breaking period or a ridging period before transplanting to play a role in controlling soil insects;

preferably, in the mixture, the weight ratio of the bacterial strain or the microbial preparation to the organic fertilizer or the fine soil is 1: 10.

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