Application of strains BHI3, BHI71, BHI77 and BHI79 in inhibition of growth and development of bactrocera cucurbitae larvae

Abstract

The invention discloses application of strains BHI3, BHI71, BHI77 and BHI79 in inhibition of growth and development of bactrocera cucurbitae larvae. Experimental results show that lactococcus lactis BHI3, enterococcus faecalis BHI71, roaming coccus fluvialis BHI77 and enterococcus glycolyticus BHI79 are used for inhibiting growth and development of bactrocera cucurbitae larvae, and have a relatively good inhibiting effect on the average survival rate, the weight of the bactrocera cucurbitae larvae and the weight of pupae of the bactrocera cucurbitae larvae; therefore, the lactococcus lactis BHI3, the enterococcus faecalis BHI71, the roaming coccus fluvialis BHI77 and the enterococcus glycolyticus BHI79 can be used for preventing and treating the bactrocera cucurbitae and have a relatively good application prospect.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and particularly relates to application of strains BHI3, BHI71, BHI77 and BHI79 in inhibiting the growth and development of cucurbit fruit fly larvae. Background Art

[0002] The melon fruit fly is a serious invasive pest worldwide. Due to the unique damage patterns of the melon fruit fly larvae and the powerful flight and reproductive abilities of the adults, chemical control is limited in effectiveness, and the area and severity of damage are increasing year by year. Long-term reliance on chemical control has not only led to a rapid increase in pesticide resistance but also caused serious environmental pollution. Therefore, the development of green and efficient control technologies for the melon fruit fly is crucial. Symbiotic bacteria play an important role in regulating insect behavior, growth and development, and environmental adaptability. Therefore, using symbiotic bacteria as new targets for control has great potential in developing green control technologies for the melon fruit fly. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention aims to provide the use of strains BHI3, BHI71, BHI77 and BHI79 in inhibiting the growth and development of cucurbit fruit fly larvae.

[0004] The first object of the present invention is to provide Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Romagnococcus fluvialis BHI77 and Enterococcus saccharolyticus BHI79.

[0005] Lactococcus lactis of the present invention ( Lactococcus lactis ) BHI3, its deposit number is GDMCC NO.66155 (deposit date: April 17, 2025, deposit unit code: GDMCC-Guangdong Provincial Microbial Culture Collection Center).

[0006] The Enterococcus faecalis of the present invention ( Enterococcus faecalis ) BHI71, its deposit number is GDMCCNO.66156 (deposit date: April 17, 2025, deposit unit code: GDMCC-Guangdong Provincial Microbiological Culture Collection Center).

[0007] The river rover bacteria of the present invention ( Vagococcus fluvialis ) BHI77, its deposit number is GDMCCNO.66157 (deposit date: April 17, 2025, deposit unit code: GDMCC-Guangdong Provincial Microbiological Culture Collection Center).

[0008] Enterococcus saccharolyticus of the present invention ( Enterococcus saccharolyticus ) BHI79, its deposit number is GDMCC NO.66158 (deposit date: April 17, 2025, deposit unit code: GDMCC-Guangdong Provincial Microbial Culture Collection Center).

[0009] A second object of the present application is to provide the use of Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavidus BHI77 and / or Enterococcus saccharolyticus BHI79 in the prevention and control of B. cucurbitae.

[0010] Preferably, the use is the use in inhibiting the growth and development of B. cucurbitae larvae.

[0011] Preferably, the use is the use in reducing the survival rate, weight of B. cucurbitae larvae and inhibiting the pupation of larvae.

[0012] A third object of the present application is to provide a microbial agent containing at least one of the Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavidus BHI77 and Enterococcus saccharolyticus BHI79.

[0013] A fourth object of the present application is to provide a method for preventing and controlling B. cucurbitae by applying the microbial agent to B. cucurbitae or an area in need of prevention and control of B. cucurbitae.

[0014] Preferably, the B. cucurbitae is B. cucurbitae larvae.

[0015] The experimental results of the present application show that Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavidus BHI77 and Enterococcus saccharolyticus BHI79 inhibit the growth and development of B. cucurbitae larvae, and have a good inhibitory effect on the average survival rate, weight of B. cucurbitae larvae and pupa weight, so that Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavidus BHI77 and Enterococcus saccharolyticus BHI79 can be used for B. cucurbitae prevention and control, and have a good application prospect.

[0016] Deposit Description The present application provides a microbial agent containing at least one of the Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavidus BHI77 and Enterococcus saccharolyticus BHI79. Lactococcus lactis BHI3 (Lactococcus lactis BHI3) has been deposited with the Guangdong Microbial Culture Collection Center on April 17, 2025, with a deposit number of GDMCC NO. 66155, a deposit unit code of GDMCC-Guangdong Microbial Culture Collection Center, and an address of the deposit unit of 5th Floor, Building 59, 100 Middle Liangma Street, Guangzhou.

[0017] The present application provides a microbial agent containing at least one of the Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavidus BHI77 and Enterococcus saccharolyticus BHI79. Enterococcus faecalis BHI71 (Enterococcus faecalis BHI71) has been deposited with the Guangdong Microbial Culture Collection Center on April 17, 2025, with a deposit number of GDMCC NO. 66156, a deposit unit code of GDMCC-Guangdong Microbial Culture Collection Center, and an address of the deposit unit of 5th Floor, Building 59, 100 Middle Liangma Street, Guangzhou.

[0018] The present application provides a microbial agent containing at least one of the Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavidus BHI77 and Enterococcus saccharolyticus BHI79. Vagococcus fluvialisBHI77 (Enterococcus dissolvens BHI77) was deposited at Guangdong Microbial Culture Collection Center on April 17, 2025, with the deposit number of GDMCC NO. 66157, the deposit unit code of GDMCC-Guangdong Microbial Culture Collection Center, and the address of the deposit unit of 5th Floor, Building 59, 100 Middle Liangma Street, Guangzhou.

[0019] The present application relates to Enterococcus saccharolyticus BHI79 (Enterococcus dissolvens BHI79) was deposited at Guangdong Microbial Culture Collection Center on April 17, 2025, with the deposit number of GDMCC NO. 66158, the deposit unit code of GDMCC-Guangdong Microbial Culture Collection Center, and the address of the deposit unit of 5th Floor, Building 59, 100 Middle Liangma Street, Guangzhou. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the growth curve of BHI3, BHI71, BHI77 and BHI79 strains.

[0021] Figure 2 is the gram staining of BHI3 strain; the scale on the figure represents 20 μm.

[0022] Figure 3 is the colony morphology of BHI3 strain.

[0023] Figure 4 is the gram staining of BHI71 strain; the scale on the figure represents 20 μm.

[0024] Figure 5 is the colony morphology of BHI71 strain.

[0025] Figure 6 is the gram staining of BHI77 strain; the scale on the figure represents 20 μm.

[0026] Figure 7 is the colony morphology of BHI77 strain.

[0027] Figure 8 is the gram staining of BHI79 strain; the scale on the figure represents 20 μm.

[0028] Figure 9 is the colony morphology of BHI79 strain.

[0029] Figure 10 is the phylogenetic tree of BHI3 strain.

[0030] Figure 11 is the phylogenetic tree of BHI71 strain.

[0031] Figure 12is a phylogenetic tree of BHI77 strain.

[0032] Figure 13 is a phylogenetic tree of BHI79 strain.

[0033] Figure 14 is the effect of different strains on the survival rate of the larvae of the fruit fly.

[0034] Figure 15 is the effect of different strains on the weight of the larvae of the fruit fly.

[0035] Figure 16 is the effect of different strains on the weight of the pupae of the fruit fly. DETAILED DESCRIPTION

[0036] The following examples are further illustrations of the application and are not intended to limit the present application.

[0037] The test insects used in the following examples are as follows: The fruit fly test population was established by feeding zucchini indoors. Environmental conditions: temperature: 26℃±1℃; relative humidity: 40%-70%; photoperiod L:D=14:10.

[0038] Example 1: Isolation, purification and identification of strains BHI3, BHI71, BHI77 and BHI79 1.1 Preparation of culture medium BHI liquid medium: 10 g of tryptone, 2.5 g of disodium hydrogen phosphate, 5.0 g of sodium chloride, 2.0 g of glucose, 500 mL of bovine heart infusion (17.5 g), add distilled water or deionized water to 1 L, final pH 7.4±0.2, high-pressure steam sterilization 121℃, 15 min.

[0039] BHI solid medium: 15 g of agar powder is added to 1 L of BHI liquid medium.

[0040] 1.2 Isolation and purification of strains In order to isolate and purify cultivable strains from the 3-day rotten zucchini fed by the larvae of the fruit fly, the obtained rotten zucchini samples were diluted into 8 concentration gradients (10 -1 -10 -8 ), 3 replicates were prepared for each sample, 100 μL of the diluted sample was spread on the BHI solid medium with a glass spreader, then incubated at 28℃±1℃ for 12 h, and single colonies were purified. The growth curves of BHI3, BHI71, BHI77 and BHI79 strains cultured at 28℃±1℃ are shown in Figure 1 .

[0041] 1.3 Strain identification 1.3.1 Morphological identification of strain BHI3 The purified strain BHI3 was inoculated with a coating rod on BHI solid plates, 30°C, 12 h, and the single colony morphology was observed; and the strain was stained with a Gram staining kit (Beijing Solaybao Technology Co., Ltd.) to observe the morphology and staining results of the strain.

[0042] The results showed that the BHI3 strain colony was round, with smooth and neat edges, no obvious serrations or expansion, milky white or light yellow, and some strains may be translucent, with a weak luster (similar to butter) (Fig. 1A). Figure 3 The strain was Gram-positive, with blue-purple staining (Fig. 1B), spherical or oval (coccus), and the typical morphology was short chains or paired arrangement, with occasional single cells. Figure 2

[0043] 1.3.2 Molecular identification of strain BHI3 The bacterial genomic DNA extraction kit (Beijing Tiangeng Biochemical Technology Co., Ltd.) was used to extract the BHI3 genomic DNA from the activated bacterial solution as a template, and the bacterial 16S rDNA gene universal primers 27F / 1492R were used for PCR amplification. Primer sequences: 27F (5'-AGAGTTTGATCCTGGCTCA-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3'). The 16S rDNA sequence amplified by PCR (the nucleotide sequence is shown as SEQ ID NO. 1) was analyzed by Blast sequence alignment using NCBI, and a phylogenetic tree was constructed using MEGA11 (Fig. 2). Figure 10 Strain BHI3 was located in the same branch as Lactococcus lactis, and the results showed that strain BHI3 was Lactococcus lactis (Lactococcus lactis) (Lactococcus lactis). Lactococcus lactis Therefore, it was named Lactococcus lactis (Lactococcus lactis) BHI3. Lactococcus lactis

[0044] 1.3.3 Morphological identification of strain BHI71 The purified strain BHI71 was inoculated with a coating rod on BHI solid plates, 30°C, 12 h, and the single colony morphology was observed; and the strain was stained with a Gram staining kit (Beijing Solaybao Technology Co., Ltd.) to observe the morphology and staining results of the strain.

[0045] The results showed that the BHI71 strain was white or buttery, the colony was round, the diameter was generally between 1-3 mm, the surface was smooth and shiny, and the edges were neat. The colony texture was relatively tight, and sometimes it may present a slight convexity (Fig. 3A). Figure 5 ​​). BHI71 strain is a gram-positive bacterium, stained blue-purple, spherical or oval, mostly in pairs or short chains, occasionally single dispersed ( Figure 4 ).

[0046] 1.3.4 Molecular identification of strain BHI71 The bacterial genomic DNA extraction kit (Beijing Tiangen Biochemical Technology Co., Ltd.) was used to extract the BHI71 genomic DNA from the activated bacterial solution as a template, and the bacterial 16S rDNA gene universal primer 27F / 1492R was used for PCR amplification. Primer sequence: 27F (5'-AGAGTTTGATCCTGGCTCA-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3'). The 16S rDNA sequence amplified by PCR (the nucleotide sequence is shown as SEQ ID NO. 2) was analyzed by Blast sequence comparison using NCBI, and the phylogenetic tree was constructed by MEGA11 ( Figure 11 ), and strain BHI71 and Enterococcus faecalis were located in the same branch. The results showed that strain BHI71 was Enterococcus faecalis ( Enterococcus faecalis ), and therefore named Enterococcus faecalis ( Enterococcus faecalis ) BHI71.

[0047] 1.3.5 Morphological identification of strain BHI77 The purified strain BHI77 was inoculated with a coating rod on a BHI solid plate, 30°C, 12 h, and the single colony morphology was observed; and the strain was stained with a gram staining kit (Beijing Solaybao Technology Co., Ltd.), and the strain morphology and staining results were observed.

[0048] The results showed that the BHI77 strain colony was round, with a neat edge (occasionally slightly jagged), the strain was milky white or light yellow, a small colony that was translucent to opaque, the colony center was thicker than the edge, soft and easy to pick up, and non-adhesive ( Figure 7 ). BHI77 strain is a gram-positive bacterium, stained blue-purple, spherical or oval, mostly in pairs or short chains, occasionally single dispersed ( Figure 6 ).

[0049] 1.3.6 Molecular identification of strain BHI77 Bacterial genomic DNA extraction kit (Beijing Tiangen Biochemical Technology Co., Ltd.) was used to extract BHI77 genomic DNA from activated bacteria solution as a template, and bacterial 16S rDNA gene universal primer 27F / 1492R was used for PCR amplification. Primer sequence: 27F (5'-AGAGTTTGATCCTGGCTCA-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3'). The 16S rDNA sequence amplified by PCR (the nucleotide sequence is shown as SEQ ID NO. 3) was analyzed by Blast sequence alignment using NCBI, and MEGA11 was used to construct a phylogenetic tree (Figure 1). Figure 12 The results showed that strain BHI77 was V. fluvialis ( Vagococcus fluvialis ), so it was named V. fluvialis ( Vagococcus fluvialis ) BHI77.

[0050] 1.3.7 Morphological identification of strain BHI79 The purified strain BHI79 was inoculated with a coating rod on a BHI solid plate, 30°C, 12 h, and the single colony morphology was observed. Gram staining kit (Beijing Solaybao Technology Co., Ltd.) was used for Gram staining of the strain, and the strain morphology and staining results were observed.

[0051] The results showed that the BHI79 strain colony was round, with neat edges, occasional slight jaggedness, grayish white or milk white, semi-transparent to opaque, thick in the center of the colony, soft and easy to pick up, and no stickiness ( Figure 9 ). BHI79 strain was Gram-positive bacteria, stained blue-purple, most arranged in pairs of short chains (4-6 cells), about 1.0 μm in diameter, and regular in shape ( Figure 8 ).

[0052] 1.3.8 Molecular identification of strain BHI79 Bacterial genomic DNA extraction kit (Beijing Tiangen Biochemical Technology Co., Ltd.) was used to extract BHI79 genomic DNA from activated bacteria solution as a template, and bacterial 16S rDNA gene universal primer 27F / 1492R was used for PCR amplification. Primer sequence: 27F (5'-AGAGTTTGATCCTGGCTCA-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3'). The 16S rDNA sequence amplified by PCR (the nucleotide sequence is shown as SEQ ID NO. 4) was analyzed by Blast sequence alignment using NCBI, and MEGA11 was used to construct a phylogenetic tree (Figure 1). Figure 13), and strain BHI79 was in the same branch with Enterococcus dissolvens. The results showed that strain BHI79 was Enterococcus dissolvens Enterococcus saccharolyticus ), and therefore was named Enterococcus dissolvens Enterococcus saccharolyticus ) BHI79.

[0053] Example 2: Determination of the survival rate, larval weight and pupal weight of D. cucurbitae larvae by Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavescens BHI77 and Enterococcus dissolvens BHI79 I. Preparation of sterile larvae 1. Preparation of sterile larval diet of D. cucurbitae Prepare the larval sterile diet in a 2 L plastic beaker. The component ratio of the larval diet is: 1 g of yeast powder, 7.5 g of white sugar, 37.5 g of wheat bran, 5 g of toilet paper, and 145 mL of distilled water. The order of addition is: distilled water, toilet paper (add water first and then add toilet paper to allow the toilet paper to soak fully and make the subsequent stirring more uniform), then add yeast powder, white sugar, and wheat bran, and stir with a glass rod until uniform. Then transfer the uniformly stirred diet to a centrifuge tube, transfer 15 mL of larval diet to a 50 mL flat-bottomed centrifuge tube, use a spoon to evenly spread the diet on the bottom of the test tube, then seal with a sealing film, and place the prepared diet in a plastic box. Sterilize the sterile diet in an autoclave at 121 °C and 15 psi for 30 min. Be careful not to shake vertically when taking the diet out of the autoclave to prevent the diet from transferring to the edge of the centrifuge tube and the sealing film. The diet can be stored at 4-15 °C for up to one week.

[0054] 2. Collecting eggs of D. cucurbitae Cut fresh cucumber slices that are not infected with bacteria and place them on a culture dish. Place the culture dish in an insect rearing cage and allow the D. cucurbitae to lay eggs for 12 h. Then remove the cucumber slices.

[0055] 3. Preparation of sterile eggs of D. cucurbitae Wash some experimental equipment including 3 x 250 mL tissue culture bottles, 500 mL brown flasks, culture dishes, sterile water, a brush, a filter screen, etc. with newspaper, and sterilize them in an autoclave at high temperature (121 °C) and high pressure (15 psi) for 30 min. Place the sterilized experimental equipment in an oven at 60 °C for 12 h to dry.

[0056] Spray the new clean work solution to the environment around the clean bench, and then treat with 84 disinfectant for 30 min; wipe the clean bench with the new clean work solution, and then wipe with 75% alcohol after 30 min; put the above sterilized experimental equipment into the clean bench, and sterilize the surface with 75% alcohol before putting it in; put the prepared 2.5% sodium hypochlorite solution into the clean bench (sodium hypochlorite decomposes under light) and sterilize with ultraviolet light for 30 min. Use a brush to transfer the eggs laid by the fruit flies on the cucumber slices to the filter screen (sterilize the cucumber slices with 75% alcohol before putting them into the clean bench), and fill 75% alcohol, sterile water and 2.5% sodium hypochlorite solution into three 250 mL tissue culture bottles respectively. Treat the fruit fly eggs on the filter screen as follows: (1) soak in 75% alcohol for 5 min, and then take out; (2) rinse in sterile water for 1 min, and then take out; (3) rinse in 2.5% sodium hypochlorite for 3 min, and then take out; (4) rinse in sterile water for 1 min, and then take out; (5) soak in 75% alcohol for 5 min, and then take out; (6) rinse in sterile water for 1 min, and then take out and put into sterile feed.

[0057] II. Backfilling of Aseptic Larvae (1) Preparation of Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus rhaerium BHI77 and Enterococcus dissolvens BHI79 strains: single colonies of the isolated and identified strains were selected into appropriate liquid medium and cultured under appropriate conditions.

[0058] (2) Detect the OD600 value of the bacterial culture liquid after dilution at 1:1, 1:2 and 1:4, spread the diluted bacterial liquid on BHI solid medium for culture, count the CFU number, standardize the bacterial number in the culture liquid of different strains, and realize standardization by the following formula: E = ((O-B) × V × D) / C, wherein E is the volume of sterile water required for resuspension of bacterial bodies, O is the OD600 value of the cultured bacterial liquid, B is the OD600 value of the blank culture liquid, D is the dilution multiple, V is the volume of the bacterial liquid before centrifugal collection of bacterial bodies, and C is the bacterial constant. The above volume units are microliters (μL).

[0059] (3) Add 100 μL of the bacterial liquid after standardization of the bacterial number to the sterile larva-rearing tube, add the same volume of BHI liquid medium to the control group, and place the high-temperature sterilized larva feed and sterile eggs at the bottom of the tube. Seal the tube with a sterile sealing film, and place the larva-rearing tube in a constant temperature incubator with a temperature of 27°C and a relative humidity of 70%.

[0060] (4) Detection of the growth and development of the larvae: we observed the survival rate, weight of the larvae and weight of the pupae after the bacteria were back-fed. The rearing tube was opened, and the rearing tube was inverted on a culture dish, and the feed and larvae were poured out. The larvae were placed in a centrifuge tube with a pen (the centrifuge tube was peeled off before weighing), and the larvae were weighed on an electronic analytical balance. In order to better observe the subsequent physiological indicators, 15 mL of fine sand was filled into a 50 mL centrifuge tube, the tube opening was sealed with a sealing film, high temperature (121°C) and high pressure (15 psi) sterilization for 30 min, and 3 mL of sterile water was added (to ensure that it is the same as the normal pupa environment), and the larvae grown in the feed for 7 days were picked into the sterile fine sand to pupate, and the pupae were weighed on an electronic analytical balance.

[0061] The above experimental steps (1) - (4) are carried out in a clean bench, except for the weighing of the larvae and pupae.

[0062] According to the above experimental method, a total of 18 strains (in addition to the above-mentioned Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavidus BHI77 and Enterococcus saccharolyticus BHI79, 12 other better strains isolated and purified in the previous experiment according to the method of "1.2 Isolation and purification of strains" are included, and the numbers are as follows: LB2, LB5, LB21, LB73, LB131, BHI4, BHI5, BHI17, BHI28, BHI41, BHI67, BHI68) were detected for their effects on the weight of the larvae, the weight of the pupae and the survival rate of the larvae of the fruit fly. The average survival rate ( Figure 14 ), the weight of the larvae ( Figure 15 ) and the weight of the pupae ( Figure 16 ) of the above four strains (Lactococcus lactis BHI3, Enterococcus faecalis BHI71, Enterococcus flavidus BHI77 and Enterococcus saccharolyticus BHI79) all had a good inhibitory effect on the larvae of the fruit fly.

[0063] During the experiment, the average survival rate, weight of the larvae and weight of the pupae of the CR (Conventionally Reared, normal feed feeding, i.e. using the sterile feed prepared in "I. Preparation of sterile larvae 1. Preparation of sterile feed for fruit fly larvae" to parallel culture the eggs of the fruit fly without sterilization) fruit fly larvae were 73.33±11.93%, 18.76±0.76 mg and 15.48±1.07 mg, respectively.

[0064] During the experiment, the average survival rate, weight of the larvae and weight of the pupae of the GF (Germ-free, sterile feeding, i.e. the control group in the above "II. Backfeeding of sterile larvae") fruit fly larvae were 71.33±5.13%, 13.81±1.80 mg and 9.87±0.37 mg, respectively.

[0065] The average survival rate and the weight of the larvae of the GF+BHI3 group (the group in the above-mentioned "II, backfilling of sterile larvae" adds BHI3 bacterial solution to the sterile rearing tube, that is, the difference between the sterile rearing group is that the strain BHI3 is added, and the expression of other groups is similar to this group) of the bactrocera cucurbitae larvae are 42.00±10.15% and 2.55±0.38 mg respectively, and the larvae are too small to pupate.

[0066] The average survival rate and the weight of the larvae of the GF+BHI71 group of the bactrocera cucurbitae larvae are 45.67±8.08% and 4.42±0.49 mg respectively during the experiment, and the larvae are too small to pupate.

[0067] The average survival rate and the weight of the larvae of the GF+BH77 group of the bactrocera cucurbitae larvae are 13±10% and 1.8±0.95 mg respectively during the experiment, and the larvae are too small to pupate.

[0068] The average survival rate and the weight of the larvae of the GF+BH79 group of the bactrocera cucurbitae larvae are 26.67±3.51% and 3.07±0.37 mg respectively during the experiment, and the larvae are too small to pupate.

[0069] No matter the survival rate of the larvae, the weight of the larvae or the weight of the pupae, the sterile larvae of the four groups of bacteria (lactococcus BHI3, enterococcus BHI71, enterococcus BHI77 and enterococcus BHI79, that is, the GF+BHI3 group, the GF+BHI71 group, the GF+BH77 group and the GF+BH79 group) are significantly different from the normal rearing of the bactrocera cucurbitae larvae.

[0070] The GF+BHI3 group, the GF+BHI71 group, the GF+BH77 group and the GF+BH79 group have better inhibitory effect on the survival rate, the weight of the larvae and the weight of the pupae of the bactrocera cucurbitae larvae than other groups (the GF+LB2 group, the GF+LB5 group, the GF+LB21 group, the GF+LB73 group, the GF+LB131 group, the GF+BHI4 group, the GF+BHI5 group, the GF+BHI17 group, the GF+BHI28 group, the GF+BHI41 group, the GF+BHI67 group and the GF+BHI68 group). It is shown that lactococcus BHI3, enterococcus BHI71, enterococcus BHI77 and enterococcus BHI79 can better inhibit the growth and development of the bactrocera cucurbitae larvae.

[0071] Therefore, the lactococcus BHI3, enterococcus BHI71, enterococcus BHI77 and enterococcus BHI79 strains of the application have good application prospect.

Claims

1. Lactococcus lactis ( Lactococcus lactis ) BHI3, characterized in that The deposit number is GDMCCNO.66155.

2. Enterococcus faecalis ( Enterococcus faecalis ) BHI71, characterized in that The deposit number is GDMCCNO.66156.

3. Fluvial rogue bacteria ( Vagococcus fluvialis ) BHI77, characterized in that The deposit number is GDMCCNO.66157.

4. Enterococcus saccharolytica ( Enterococcus saccharolyticus ) BHI79, characterized in that The deposit number is GDMCC NO.66158.

5. Use of the Lactococcus lactis BHI3 according to claim 1, the Enterococcus faecalis BHI71 according to claim 2, the Rampantococcus fluvii BHI77 according to claim 3, and / or the Enterococcus saccharolyticus BHI79 according to claim 4 in controlling Bactrocera cucurbitae.

6. The use according to claim 5, characterized in that The application is application in inhibiting the growth and development of melon fruit fly larvae.

7. The use according to claim 6, characterized in that The application is to reduce the survival rate and insect weight of melon fruit fly larvae and inhibit the larvae from pupating.

8. A bacterial agent, characterized in that Contains at least one of the Lactococcus lactis BHI3 according to claim 1, the Enterococcus faecalis BHI71 according to claim 2, the Rampantococcus fluvialis BHI77 according to claim 3, and the Enterococcus saccharolyticus BHI79 according to claim 4.

9. A method for controlling melon fruit flies, characterized in that: The bacterial agent according to claim 8 is applied to the cucurbit fruit fly or to the area where the cucurbit fruit fly needs to be controlled.

10. The method according to claim 9, characterized in that The cucurbit fruit fly is a cucurbit fruit fly larva.

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