A strain of Beauveria bassiana and its application in controlling red imported fire ants

Abstract

The present invention discloses a strain of Beauveria bassiana and its application in preventing and controlling red fire ants. The present invention isolates an entomogenous fungus strain from a termite, and identifies it as Beauveria bassiana SCAU‑BbFa01 through morphological and molecular identification, with a deposit number of GDMCC NO.62643; and uses a bioassay method to evaluate the toxicity of the strain to red fire ants of different grades, and finds that the strain has the characteristics of high efficiency in infecting red fire ants, especially significant infection effects on larvae and pupae of red fire ants; and has the advantages of no pollution, no residue, biological environmental protection, etc. during the application process, and has good application prospects in the green prevention and control of red fire ants.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and particularly relates to a strain of Beauveria bassiana and application thereof in preventing and controlling red imported fire ants. Background Art

[0002] Red fire ants are one of the most dangerous invasive species in the world. Since the 1930s, they have invaded North America, Australia, Asia and other countries and regions, posing serious threats to agricultural and forestry production, human and animal health, and biodiversity. Since the red fire ants invaded my country in 2004, they have been common in southern provinces of my country. Since red fire ants have many ways to spread, have obvious population competitive advantages and high reproductive capacity, and have no natural enemies to inhibit them in new invasion areas, they are quite difficult to control. At present, the prevention and control of red fire ants mainly relies on chemical control, but its disadvantage is that the entire red fire ant-infested area needs to be treated, otherwise the red fire ants will invade again. Since the use of chemical agents leads to serious "3R" problems, biological control methods for red fire ants have received widespread attention from researchers.

[0003] Entomogenous fungi are a biological limiting factor in the living environment of red fire ants. The use of entomogenous fungi is an important part of the biological control of red fire ants, and has the unique advantage of sustainable control of red fire ants. Summary of the invention

[0004] The invention aims to provide a strain of Beauveria bassiana with high pathogenicity to red imported fire ants, and utilize the strain to control the red imported fire ants.

[0005] The invention separates a Beauveria bassiana strain SCAU-BbFa01 which is highly pathogenic to red imported fire ants from the body of Coptotermes formosanus.

[0006] The morphological characteristics of strain SCAU-BbFa01 are as follows:

[0007] The strain SCAU-BbFa01 can grow white hyphae on PDA medium for 3-5 days. The colony is velvety, white, and bulging in the middle. On the 6th day, it produces light yellow powdery spores. Later, the colony turns light yellow, and the back is yellow. The conidiophores are 1-2 μm thick. The spore-producing cells are clustered on the hyphae, conidiophores or swollen cysts. They are bottle-shaped, and the neck is obviously extended to a spore-producing axis with a thickness of 1 μm and a length of 20 μm. The axis has small teeth and is bent in a zigzag shape. The conidia are spherical or nearly spherical, transparent and smooth, 2-3×2-2.5μm.

[0008] Molecular identification of strain SCAU-BbFa01:

[0009] The genomic DNA of strain SCAU-BbFa01 was used as template and the universal primer ITS1 was used for fungi.

[0010] (5'-TCCGTAGGTGAACCTGCGG-3') / ITS4(5'-TCCTCCGCTTATTGATATGC-3') was used to amplify the rDNA-ITS sequence of the strain by PCR and sequenced. The sequence was then compared and analyzed for homology in the NCBI gene library, and it was found that the strain belonged to the genus Beauveria. Based on phylogenetic analysis, the strain was found to belong to Beauveria bassiana. Combined with the morphological characteristics of the strain and rDNA-ITS sequence analysis, it was determined that the target strain belonged to the genus Beauveria and was named Beauveriabassiana SCAU-BbFa01.

[0011] Therefore, the first object of the present invention is to provide a strain of Beauveria bassiana SCAU-BbFa01, whose deposit number is GDMCC NO.62643.

[0012] The present invention also provides application of the Beauveria bassiana SCAU-BbFa01 in preventing and controlling red imported fire ants.

[0013] Preferably, the use comprises the step of contacting the Beauveria bassiana SCAU-BbFa01 or a culture containing the Beauveria bassiana SCAU-BbFa01 with the bodies of red imported fire ants.

[0014] Preferably, the culture of Beauveria bassiana SCAU-BbFa01 is a bacterial suspension of Beauveria bassiana SCAU-BbFa01, with a concentration of 1×10 4 -1×10 8 spores / mL.

[0015] Preferably, the application comprises the step of spraying the bacterial suspension of Beauveria bassiana SCAU-BbFa01 on the bodies of red fire ants.

[0016] Preferably, the application comprises the step of mixing the bacterial suspension of Beauveria bassiana SCAU-BbFa01 into the soil in the living environment of red imported fire ants.

[0017] Preferably, the red fire ants are red fire ants worker ants, larvae or pupae.

[0018] The present invention also provides a biocontrol preparation for preventing and controlling red imported fire ants, which contains the Beauveria bassiana SCAU-BbFa01 or a culture containing the Beauveria bassiana SCAU-BbFa01.

[0019] Preferably, the biocontrol agent is a suspension of Beauveria bassiana SCAU-BbFa01, with a concentration of 1×10 4 -1×10 8 spores / mL.

[0020] The Beauveria bassiana SCAU-BbFa01 of the present invention has the characteristics of efficiently infecting red fire ants, especially having a significant infection effect on red fire ant larvae and pupae; and has no pollution, no residue, and is biologically environmentally friendly during the application process, and is a strain with good application prospects in the field of entomogenous fungi.

[0021] Storage Instructions:

[0022] The Beauveria bassiana SCAU-BbFa01 (Beauveria bassiana SCAU-BbFa01) of the present invention was deposited in the Guangdong Microbiological Culture Collection Center (GDMCC) on July 21, 2022, with a deposit number of GDMCC NO.62643, and a deposit address of 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou, Institute of Microbiology, Guangdong Academy of Sciences. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Figure 1 is the colony morphology, hyphae and conidia morphology of strain SCAU-BbFa01 on PDA medium; Figure A is the colony morphology of strain SCAU-BbFa01 grown on PDA medium for 10 days, Figure B is the hyphae and conidia morphology of strain SCAU-BbFa01 under an optical microscope, and Figure C is the detailed morphology of conidiophores, spore-forming cells and conidia of strain SCAU-BbFa01.

[0024] Figure 2 This is the phylogenetic tree of strain SCAU-BbFa01 based on rDNA-ITS sequence; the numbers in brackets in the figure are the numbers of the corresponding strains in the Genbank database.

[0025] Figure 3 These are morphological pictures of the strain SCAU-BbFa01 infecting red fire ants; wherein Figure A is a morphological picture of the strain SCAU-BbFa01 infecting red fire ant workers for 6 days, Figure B is a morphological picture of the strain SCAU-BbFa01 infecting red fire ant workers for 10 days, Figure C is a morphological picture of the strain SCAU-BbFa01 infecting red fire ant larvae for 3 days, and Figure D is a morphological picture of the strain SCAU-BbFa01 infecting red fire ant pupae for 3 days.

[0026] Figure 4 Figure 3 is the trend of the cumulative mortality of red fire ant workers / larvae and pupae treated with different concentrations of SCAU-BbFa01 strain over time; Figure A is the cumulative mortality of worker ants under the spore suspension treatment; Figure B is the cumulative mortality of larvae under the spore suspension treatment; Figure C is the cumulative mortality of pupae under the spore suspension treatment. DETAILED DESCRIPTION

[0027] The following examples are provided to further illustrate the present invention, rather than to limit the present invention.

[0028] Example 1: Identification of strain SCAU-BbFa01

[0029] A fungus strain (strain number SCAU-BbFa01) was isolated from the body of domestic termites and its species was identified by morphological and molecular identification under laboratory conditions.

[0030] 1. Experimental plan

[0031] 1. Preparation of culture medium for strain characterization

[0032] The isolated strain was inoculated into potato dextrose agar (PDA) medium (potato 200 g / L, glucose 20 g / L, agar 20 g / L, distilled water 1000 mL) and cultured in a constant temperature incubator at 25±1°C, photoperiod L:D=12h:12h, and relative humidity 80±5%.

[0033] 2. Morphological identification

[0034] According to the "Handbook of Fungal Identification" compiled by Wei Jingchao, the morphological characteristics of the strains were clarified. The strains were identified according to the methods introduced in the "Microbiology Experiment Manual" compiled by Zhou Deqing et al. (Shanghai: Science and Technology Press).

[0035] 3. Molecular Identification

[0036] A small number of single colonies were picked and the genomic DNA of the strain was extracted using a fungal kit. Using the genomic DNA as a template, the rDNA-ITS sequence was PCR amplified using the universal primers for fungi: ITS1: 5'-TCCGTAGGTGAACCTGCGG-3', ITS4: 5'-TCCTCCGCTTATTGATATGC-3'. The amplification system was 50 μL, containing 2×Pri-113 Max DNA 25μL, forward and reverse primers 2μL each, ddH2O 19μL, DNA template 2μL, and finally deionized sterilized ultrapure water to adjust the total reaction volume to 50μL. Amplification conditions: 95℃5min; 95℃30s, 60℃30s, 72℃1min, 35 cycles; 72℃5min. PCR amplified the target fragment and sent it to Sangon Biotech (Shanghai) Co., Ltd. for sequencing. Subsequently, the sequence was corrected by Chromas sequence splicing software, homology was compared in the NCBI (http: / / blast.ncbi.nlm.nih.gov / ) gene library, and the phylogenetic tree was constructed by MEGA7.0 software using the neighbor-joining method for phylogenetic analysis.

[0037] 2. Experimental Results

[0038] 1. Morphological characteristics of strains

[0039] The strain was cultured on PDA medium. Under 25°C, white hyphae can grow in 3-5 days. The colony is velvety, white, and bulging in the middle. On the 6th day, light yellow powdery spores are produced. Later, the colony turns light yellow and the back is yellow. The culture characteristics of the strain are: the growth temperature range is 4°C to 32°C, and the optimal growth temperature is 25°C-27°C; the growth pH range is 5.0 to 8.0, and it grows well under acidic conditions. The optimal growth pH range is 6.0 to 7.0; on the 10th day, the colony diameter reaches 35.67 mm, and the spore production is 5.56×10 7 Conidia / mL( Figure 1 ). Conidiophores are 1-2 μm thick, and conidial cells are clustered on hyphae, conidiophores or swollen cysts. They are bottle-shaped, with the neck obviously extended into a conidial axis with a thickness of 1 μm and a length of 20 μm. The axis has small teeth and is bent in a zigzag shape. Conidia are spherical or nearly spherical, transparent and smooth, 2-3×2-2.5 μm.

[0040] 2. rDNA-ITS sequence analysis of strains

[0041] PCR was used to amplify the rDNA-ITS sequence fragment of the target strain. The sequencing results showed that the amplified fragment was 534 bp and the nucleotide sequence was shown in SEQ ID NO.1.

[0042] The sequence was compared with the NCBI gene library by BLAST, and it was found that the similarity between the ITS sequence of the target strain and the corresponding sequences of multiple reported Beauveria bassiana strains reached more than 99%. Relevant sequences were selected and a phylogenetic tree was constructed using MEGA7.0 ( Figure 2 ).

[0043] Combined with the morphological characteristics and rDNA-ITS sequence analysis of the strain, strain SCAU-BbFa01 was identified as Beauveria bassiana, and was named Beauveria bassiana SCAU-BbFa01. The strain was deposited in Guangdong Provincial Microbiological Culture Collection Center (GDMCC) on July 21, 2022, with the deposit number: GDMCC NO.62643.

[0044] Example 2: Determination of pathogenicity of Beauveria bassiana SCAU-BbFa01 strain to red imported fire ants

[0045] 1. Experimental plan

[0046] 1. Treatment of test strains

[0047] The SCAU-BbFa01 strain of Beauveria bassiana was cultured in PDA medium, and the conidia were preserved in an ultra-low temperature refrigerator at -80°C in the Insect Ecology Laboratory of South China Agricultural University using the glycerol test tube method. During the experiment, the SCAU-BbFa01 strain of Beauveria bassiana was taken out for activation, and the SCAU-BbFa01 strain of Beauveria bassiana was inoculated on a PDA plate and placed in an incubator at 25±1°C, a light cycle of L:D=12h:12h, and a relative humidity of 80±5% for 7 days. After the colony produces spores, add 20mL of 0.03% Tween-80 sterile water, and use an inoculation needle to gently scrape the hyphae and spores to make a bacterial solution. Pour the bacterial solution into a 200mL beaker and stir with a magnetic stirrer for 30 minutes. After the spores are completely dispersed, filter the bacterial solution with a double layer of medical gauze to obtain a spore suspension, i.e., the test mother solution. The spore concentration of the mother solution is counted with a hemocytometer and prepared into 1×10 4 , 1×10 5 , 1×10 6 , 1×10 7 , 1×10 8 Spores / mL Spore suspensions at 5 test concentrations.

[0048] 2. Test insects and treatment

[0049] The red fire ant nests used in the experiment were collected from the lawn of South China Agricultural University. The nests were separated from the soil by the drip method and then raised in a 40 cm×30 cm×10 cm plastic box, with 25% honey water and mealworm larvae. The test insects were worker ants, larvae and pupae raised indoors for no more than 1 month. The red fire ant workers, larvae and pupae were placed in a plastic cup (bottom diameter 7 cm, top diameter 9 cm, height 6.5 cm), and the spore suspension of the test concentration was evenly sprayed with a micro spray pot. The treated worker ants, larvae and pupae were placed in a small plastic box with gypsum moisturizing at the bottom (bottom diameter 7 cm, top diameter 9 cm, height 6.5 cm), 100 per box. For the treated larvae or pupae, 50 untreated red fire ant workers from the same nest were added as brood ants to provide them with food and care. A needle was used to poke several small holes on the lid of the box for ventilation, and a small amount of talcum powder was applied to the inner wall of the plastic box to prevent the red fire ants from escaping. Use cotton balls to dip into 25% honey water to feed worker ants. Place each treatment in an incubator (25±1°C, photoperiod L:D=12h:12h, relative humidity 80±5%) for observation for 10 consecutive days. Check and record the number of deaths of treated worker ants, larvae, pupae and nursery ants every day, and pick the dead insect bodies into a culture dish (9 cm in diameter) covered with wet filter paper for moisturizing culture. Determine the cause of death based on whether there is hyphae growth on the insect corpses, and calculate the cumulative mortality rate of insect bodies in each treatment. Sterile water containing 0.03% Tween-80 was used as a control. Each treatment was repeated 3 times (3 nests of red fire ants).

[0050] 2. Experimental Results

[0051] The test results showed that the SCAU-BbFa01 strain had a strong pathogenicity to red fire ant workers, larvae and pupae ( Figure 3 ), at different concentrations (1×10 4 -1×10 8 spores / mL) 10 days after treatment, the cumulative mortality of worker ants was 18.31%-100%, the cumulative mortality of larvae was 42.68%-100%, and the cumulative mortality of pupae was 59.75%-100% ( Figure 4 and Table 1). In addition to infecting the inoculated larvae and pupae, the SCAU-BbFa01 strain can also be transmitted to uninoculated brooding workers through contact. The cumulative mortality rates of brooding workers fed with larvae and pupae on the 10th day were 9.33%-44.67% and 9.36%-36%, respectively.

[0052] Table 1 Cumulative corrected mortality (10 days) of each class of red imported fire ants infected with Beauveria bassiana SCAU-BbFa01

[0053]

[0054]

[0055] Note: The same letters in the same line indicate no significant difference at the 0.05 level (DMRT method)

[0056] The results of the lethal concentration of Beauveria bassiana SCAU-BbFa01 strain to various grades of red imported fire ants are shown in Table 2. The LC values ​​of worker ants, larvae and pupae on the 10th day after inoculation were 50 They are 1.05×10 5 spores / mL, 2.01×10 4 spores / mL and 1.89×10 3 spores / mL.

[0057] Table 2 The median lethal concentration of Beauveria bassiana SCAU-BbFa01 strain to various grades of red imported fire ants (10 days)

[0058]

[0059] The lethal time of Beauveria bassiana SCAU-BbFa01 strain to different grades of red imported fire ants is shown in Table 3. As the concentration of the fungal spore suspension increases, the LT of the tested red imported fire ants increases. 50 The value decreases, in 1×10 4 ~1×10 8 spores / mL, the LT of worker ants 50 From 13.54d to 2.75d, the LT of the larvae 50 From 9.18d to 1.26d. 50 From 4.66d to 0.84d.

[0060] Table 3 The median lethal time of Beauveria bassiana SCAU-BbFa01 strain to various grades of red imported fire ants

[0061]

[0062]

[0063] The results of this experiment show that the SCAU-BbFa01 strain of Beauveria bassiana has a strong pathogenicity to red fire ants, which can be concluded from its lethal concentration and lethal time for three grades of red fire ants. 50 They are 1.05×10 5 spores / mL, 2.01×10 4 spores / mL and 1.89×10 3 spores / mL. 7 spores / mL, the LT of worker ants, larvae and pupae50 The virulence of Beauveria bassiana SCAU-BbFa01 to red fire ant pupae was 3.81d, 1.56d and 0.92d respectively, which means that the pathogenicity of Beauveria bassiana SCAU-BbFa01 to red fire ant pupae was the strongest, followed by red fire ant larvae and then red fire ant workers. The Beauveria bassiana SCAU-BbFa01 strain was not only lethal to the treated red fire ant workers, larvae and pupae, but also had a certain lethal effect on the nursery workers in contact with it. This shows that the Beauveria bassiana SCAU-BbFa01 strain has a significant high pathogenicity to red fire ants.

[0064] Example 3: Transmission ability of Beauveria bassiana SCAU-BbFa01 strain in artificial nests of red imported fire ants

[0065] Red fire ants are social insects that are in close contact with each other, which is conducive to the spread of pathogenic fungi in ant nests. However, infected ants tend to stay away from ant nests in order to reduce the spread of pathogenic fungi. It has been observed that infected individuals of red fire ants stay away from ant nests. In this example, red fire ants artificially infected with Beauveria bassiana SCAU-BbFa01 were placed in healthy red fire ant nests, and the death of healthy red fire ants in the nests was observed to study the horizontal transmission of the strain in the nests.

[0066] 1. Experimental plan

[0067] 1. Preparation of SCAU-BbFa01 spore suspension of Beauveria bassiana

[0068] The SCAU-BbFa01 strain of Beauveria bassiana inoculated on the PDA plate was placed in an incubator at 25±1°C, a photoperiod of L:D=12h:12h, and a relative humidity of 80±5% for 7 days, and then prepared into 1×10 8 A spore suspension with a concentration of spores / mL.

[0069] 2. Experimental Design

[0070] A portion of red fire ant workers were treated by spraying, and the treated insects were placed in a constant temperature incubator at 25±1℃, photoperiod L:D=12h:12h, and relative humidity of 80±5% for 24h, and the live insects were taken as test insects. Inoculated worker ants and uninoculated worker ants were mixed and raised in different proportions, and 6 gradients were set up in the experiment, so that the number of inoculated red fire ants in each group accounted for 0, 5%, 15%, 50%, 85%, and 100% of the total number of red fire ants, respectively, and the total number of ants in each treatment was 100, and repeated 5 times. The mixed red fire ants were placed in a plastic cup with gypsum moisturizing at the bottom (bottom diameter 7cm, top diameter 9cm, height 6.5cm), placed in a constant temperature incubator at 25±1℃, photoperiod L:D=12h:12h, and relative humidity of 80±5%, and fed to the red fire ants with 25% honey water absorbed by cotton balls. After 15 days, the total survival rate of fire ants in different treatments and the transmission rate of Beauveria bassiana SCAU-BbFa01 from inoculated worker ants to uninoculated worker ants were examined. Transmission rate = (number of uninoculated fire ants that died of infection / number of uninoculated fire ants) × 100%.

[0071] 2. Experimental Results

[0072] After the inoculated and uninoculated ants were mixed in different proportions for 15 days, the infection rates of uninoculated ants by the SCAU-BbFa01 strain of Beauveria bassiana were significantly different in different treatments (Table 4). Under the premise that the total number of ants was the same, with the increase in the proportion of inoculated ants, the total survival rate of ants showed a gradual downward trend, while the infection rate showed a gradual upward trend. When the number of inoculated ants accounted for 85% of the total number of ants, the infection rate of SCAU-BbFa01 of Beauveria bassiana among ants reached 100%. When the number of inoculated ants accounted for 5%, 15%, and 50% of the total number of ants, the infection rates of SCAU-BbFa01 of Beauveria bassiana among ants were 69.68%, 76.71%, and 82.00%, respectively.

[0073] Table 4 Transmission ability of Beauveria bassiana SCAU-BbFa01 strain in ant nests under different treatment conditions

[0074]

[0075] *The ratio of inoculated worker ants is the percentage of inoculated worker ants to the total number of red fire ants. The same letters in the same column indicate no significant difference at the 0.05 level (DMRT method)

[0076] Example 4: The lethality of Beauveria bassiana SCAU-BbFa01 strain to red imported fire ants in soil

[0077] Red fire ants live in the soil. Foreign test results show that the soil treatment effect of Beauveria bassiana is worse than that of spores directly contacting red fire ants, mainly because the soil hinders the contact between spores and red fire ants, and the presence of a large number of microorganisms in the soil may have an antibacterial effect on Beauveria bassiana. As a result, the field experimental control effect of existing Beauveria bassiana for controlling red fire ants is not ideal. This example uses an indoor research method to explore the pathogenicity of Beauveria bassiana SCAU-BbFa01 to red fire ants in sterilized soil and non-sterilized soil.

[0078] 1. Experimental plan

[0079] 1. Soil sterilization

[0080] The soil used in the experiment was collected from the nest of red fire ants in Nansha, Panyu, Guangzhou. The stones and weeds on the surface of the nest were removed, and the soil was filtered through a 16-mesh / inch sieve for use in the experiment. The sieved soil was spread on a 40cm×30cm enamel tray, placed in a drying oven, and sterilized at 150-170℃ for 4-5h.

[0081] 2. Weighing of spore powder

[0082] Use an inoculation needle to gently scrape the SCAU-BbFa01 strain of Beauveria bassiana cultured on a PDA plate for 7 days without scraping the culture medium. Weigh 0.1g and 1g of spore powder for the test on an electronic balance. After measurement, each gram of spore powder has about 8.5×10 9 Spores.

[0083] 3. Estimation of the number of red fire ant workers

[0084] The red fire ants separated from the ant nest and raised indoors were anesthetized with CO2, and 1 g of the worker ants were weighed 5 times on an electronic balance. The number of worker ants was counted and the result was recorded each time. The average number of worker ants per gram was calculated to be 850±10.

[0085] 4. Experimental Design

[0086] Weigh 0.1g and 1g of spore powder, mix them into 100g of soil, add 10mL of sterile water, mix them in a plastic cup (bottom diameter 7cm, top diameter 9cm, height 6.5cm), add 1g of red fire ant worker ants, and use a cotton ball to absorb 25% of honey water to feed the red fire ants. The soil is divided into sterilized soil treatment and non-sterile soil treatment. The soil treatment without spore powder is set as the control, and each treatment is repeated 3 times. The treated insect body is placed in an incubator with a constant temperature of 25±1℃, a photoperiod of L:D=12h:12h, and a relative humidity of 80±5%. After 15 days of cultivation, the number of surviving red fire ants is counted, the insect body mortality rate is calculated, and the dead red fire ants are moisturized and cultured. The red fire ants that have white bassian hyphae and spores on the body surface are infected and killed by white bassian fungus, and the infection rate of the insect body is calculated. Infection rate = (number of red fire ants killed by Beauveria bassiana / total number of dead red fire ants) × 100%.

[0087] 2. Experimental Results

[0088] After 15 days, the worker ant deaths in each treatment group and the control group are shown in Table 5. Dead worker ants carried in piles can be seen on the soil surface. The dead worker ants treated with bacteria have Beauveria bassiana on their bodies, while the dead worker ants in the control group have no Beauveria bassiana on their bodies. The experimental results show that the worker mortality rate of red fire ants treated with sterilized soil mixed with bacteria is significantly higher than that of unsterilized soil mixed with bacteria, while there is no significant difference between the two control groups. Under the same soil treatment, the worker mortality rate of red fire ants treated with different concentrations of spore powder is also different. The mortality rate of red fire ants treated with high concentrations of spore powder is significantly higher than that of low concentrations, and both are significantly higher than the control.

[0089] Although the soil prevents direct contact between spores and insects, its pathogenicity is relatively weakened. However, despite this, the mortality rate of Beauveria bassiana SCAU-BbFa01 on red fire ant workers can reach 62.27% after being treated in non-sterile soil. The above results show that Beauveria bassiana SCAU-BbFa01 can still cause pathogenicity to red fire ants in soil, indicating that this strain has certain practical application potential.

[0090] Table 5 Mortality of red imported fire ant workers after soil treatment with Beauveria bassiana SCAU-BbFa01 strain (%)

[0091]

[0092] Note: The same lowercase letters in the same column of data in the table indicate that there is no significant difference at the 0.05 level (DMRT method); the same uppercase letters in the same row of data indicate that there is no significant difference between the treatment and the control at the 0.05 level.

[0093] The results showed that for the social insect red fire ant, the SCAU-BbFa01 strain of Beauveria bassiana can be successfully transmitted in the ant nest through body wall contact between red fire ant individuals, indicating that the SCAU-BbFa01 strain of Beauveria bassiana has great potential in the practical application of red fire ant prevention and control.

Claims

1. A strain of Beauveria bassiana SCAU-BbFa01, whose deposit number is GDMCC NO.62643.

2. The use of Beauveria bassiana SCAU-BbFa01 according to claim 1 in preventing and controlling red imported fire ants, characterized in that: The red fire ants are worker ants, larvae or pupae of red fire ants.

3. The use according to claim 2, characterized in that: The method comprises the step of contacting the Beauveria bassiana SCAU-BbFa01 according to claim 1 or a culture containing the Beauveria bassiana SCAU-BbFa01 according to claim 1 with the bodies of red imported fire ants.

4. The use according to claim 3, characterized in that: The culture of Beauveria bassiana SCAU-BbFa01 is a bacterial suspension of Beauveria bassiana SCAU-BbFa01, with a concentration of 1×10 4 -1×10 8 spores / mL.

5. The use according to claim 4, characterized in that: The method comprises the step of spraying the bacterial suspension of Beauveria bassiana SCAU-BbFa01 on the bodies of red imported fire ants.

6. The use according to claim 4, characterized in that: The method comprises the steps of mixing the bacterial suspension of Beauveria bassiana SCAU-BbFa01 into the soil of the living environment of red imported fire ants.

7. A biological control agent for controlling red imported fire ants, characterized in that: A culture containing the Beauveria bassiana SCAU-BbFa01 according to claim 1 or comprising the Beauveria bassiana SCAU-BbFa01 according to claim 1.

8. The biological control agent for controlling red imported fire ants according to claim 7, characterized in that: The biocontrol agent is a suspension of Beauveria bassiana SCAU-BbFa01, with a concentration of 1×10 4 -1×10 8 spores / mL.

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