KR102172105B1 - Bacillus thuringiensis subsp. japonensis CAB452 strain having insecticidal activity and uses thereof - Google Patents

Abstract

The present invention relates to a Bacillus thuringiensis subsp. japonensis CAB452 strain having insecticidal activity against Bradysia agrestis and uses thereof. The strain of the present invention may be useful for developing a nonpolluting agent for insect pest control.

Description

Bacillus thuringiensis subspecies zaponensis CAB452 strain having insecticidal activity and its use {Bacillus thuringiensis subsp. japonensis CAB452 strain having insecticidal activity and uses thereof}

The present invention relates to a Bacillus thuringiensis subspecies zaponensis CAB452 strain having insecticidal activity and use thereof.

The small root fly ( Bradysia agrestis Sasakawa) is an insect belonging to the genus Bradysia of the Diptera family Sciaridae . In Korea, it was first reported in watermelon seedlings in a facility nursery. Flies of the genus Bradysia mainly occur in facility houses, nurseries, and mushroom cultivation houses, and in recent years, the incidence and damage are rapidly increasing in superflower seedling cultivation for planting flower beds and for domestic bonsai. In Korea, 21 crops such as pepper, watermelon, melon, cucumber, tomato, strawberry, paprika, and chrysanthemum are recorded as host plants (Lee et al., 2001, Kor. J. Appl. Entomol. 40(2): 149-153), 54 species such as begonias and carnations have been recorded as host plants of small root flies in foreign countries (Harris et al., 1995, Biol. Control. 5(3):412-418). In particular, the occurrence is severe in rock wool cultivated crops such as tomatoes and paprika, and damage has been confirmed in bulbs, which are crops using roots such as lily and ginger. As such, the density of small root flies increases due to the abundant organic matter in the soil and the humid greenhouse environment, resulting in serious damage. The symptoms of damage caused by larvae are difficult to observe with the naked eye because they gnaws like peeling off the roots or stems of plants, or invades and invades the inside of the roots through the root thimble. In addition, as well as direct damage, the larvae cause disease through overall pathogens such as Fusarium , Phoma , Pythium , and Verticillium . It also causes damage by transferring pathogens to other plants or facility houses by putting mycelium on the body such as wings (Ludwig, 2001, Pest Manag Sci. 57:1114-1118). Small root flies are difficult to control because eggs, larvae, pupae and adult insects are mixed within a short period of time when they start to occur in facility houses where crops are grown using organic matter, or all age groups except adults live in the soil or root tissue. It is a pest.

Chemical insecticides such as benfuracarb, diflubenzuron, fenthion or teflubenzuron, which are registered drugs, are used to control small root flies. However, the use of pesticides is very limited because of the problems that cause product safety, the appearance of resistant individuals, damage to humans and livestock, and environmental pollution. Therefore, there is a need for research on biological control, which is an alternative way to control small root flies safely and effectively in the environment in facility houses. Until recently, Bacillus thuringiensis strains, insect pathogenic nematodes, and predatory mites have been used for biological control of flies in the genus Badysia , but studies on biological control factors for the control of fly insects have been insufficient. Actually.

Bacillus thuringiensis has been reported to have been isolated from everyday habitats around us, such as soil, insects, fallen leaves and conifer leaves, water, stored grain powder, and sericulture (Lee et al., 2014, J. Fac. Agr. Kyushu Univ. 60:103-112). The insecticidal protein of Bacillus thuringiensis, which is widely used as a microbial insecticide, is used as a major agricultural material in eco-friendly agriculture because it is safe against non-selective organisms (Lee et al., 2014). Bacillus thuringiensis is an insect pathogenic bacterium, forms endospores with aerobic Gram-positive bacillus, and produces insecticidal proteins composed of endotoxin proteins. These insecticidal toxin proteins (Insecticidal Crystal Proteins (ICPs)) exhibit host-specific properties that vary in toxicity to various pests such as the order Lepidoptera, the order Flies, and the order Beetle. In addition, activity against logging, cicada, grasshopper, mite, nematode, and protozoa has also been reported. There is increasing interest in Bacillus thuringiensis as a biological control factor around the world, and the Bacillus thuringiensis subsp. israelensis strain, which has a high toxicity to the fly order larvae , is used to control fly order pests. It is mainly marketed as a product (Seo et al., 2010, Kor. J. Appl. Entomol. 49(2):151-158). However, there is a shortage of microbial pesticides registered to control the pests of the order Flies.

In the present invention, a new Bacillus thuringiensis strain having insecticidal activity against small root flies, which has been rapidly increased in facility cultivation, has been selected and analyzed the characteristics and marketability for use as a biological control agent.

On the other hand, Korean Patent No. 1649139 discloses'Bacillus thuringiensis subspecies Aizawai CAB566 strain having insecticidal activity and its use', and Korean Patent No. 191929913 discloses'Bacillus thuringiensis subspecies Israelen having insecticidal activity. Cis CAB575 strain and use thereof' are disclosed, but there is no description of the Bacillus thuringiensis subspecies Zaponensis CAB452 strain having insecticidal activity of the present invention and its use.

The present invention was derived from the above requirements, and the present inventors selected a new Bacillus thuringiensis strain having high insecticidal activity against Flies in the domestic soil. Among the 10 newly selected Bacillus thuringiensis strains, 3 strains with an insecticidal activity of 70% or more were first selected against the small root flies ( Bradysia agrestis ) and the Pseudomonas mosquito family ( Aedes albopictus ), Among the three selected strains, Bacillus thuringiensis CAB452 strains showing an insecticidal activity of 90% or more were selected for both small root flies and mosquitoes. In particular, Bacillus thuringiensis CAB452 strain showed an LC ₉₅ value of 4.4×10 ⁷ (cfu/ml) for small root fly larvae, and it was reported to exhibit strong insecticidal activity against mosquito larvae. ( B. thuringiensis subsp. israelensis ) Not only exhibits higher insecticidal activity than the strain, but also in the pot experiment, it was confirmed that the control effect against small root flies was remarkable compared to the Bacillus thuringiensis subsp. israelensis treatment. Completed.

In order to solve the above problems, the present invention provides a Bacillus thuringiensis subsp. japonensis ) CAB452 strain having an accession number of KCTC 13878BP and an insecticidal activity against small root flies ( Bradysia agrestis ). .

In addition, the present invention provides a small root fly ( Bradysia agrestis ) insecticidal composition comprising the strain or a culture medium thereof as an active ingredient.

In addition, the present invention provides a method of controlling small root flies ( Bradysia agrestis ) by spraying an effective amount of the strain or a culture medium thereof on plants, soil, or small root flies ( Bradysia agrestis ) habitat.

Bacillus thuringiensis subsp. japonensis of the present invention, the CAB452 strain exhibits a strong insecticidal effect against small root flies, which is a pest of the order of the Flies, so the composition of the present invention comprising the strain is an eco-friendly organic formulation. As a result, it is effective in minimizing the impact on crops and controlling pests occurring in crops, and exhibiting fast-acting properties to obtain excellent insecticidal effects against flyneck pests, so it can be usefully used for the development of non-polluting pest control agents.

1 is a view of the larvae of small root flies according to the treatment of Bacillus thuringiensis subspecies Zaponensis CAB452 strain. A: untreated control group, B: appearance of dead larvae after 3 days of treatment, C: appearance of dead larvae after 5 days of treatment.
Figure 2 shows the mortality rate of small root flies according to the Bacillus thuringiensis strain treatment. CAB452: Bacillus thuringiensis subspecies zaponensis strains, CAB599 and CAB117: Bacillus thuringiensis strains, Bt israelensis : Bacillus thuringiensis subspecies israelensis , control: untreated control.
3A is a phase contrast microscope (×1000) image of a crystal of Bacillus thuringiensis subspecies zaponensis CAB452 strain, and B is a scanning electron microscope image of crystal spores.
4 is an SDS-PAGE gel photograph confirming the results by reacting the isolated Bacillus thuringiensis toxin protein crystals with trypsin. M: size marker, lane 1: Bacillus thuringiensis subspecies zaponensis CAB452, lane 2: Bacillus thuringiensis subspecies zaponensis CAB452 cut with trypsin, lane 3: Bacillus thuringi cut with small root fly larvae Nsis subspecies Zaponensis CAB452, lane 4: Bacillus thuringiensis subspecies Israel lances, lane 5: Bacillus thuringiensis subspecies Israel lances cut with trypsin, lane 6: Bacillus thuringia cut with small root fly larvae grinding solution Nsis subspecies Israelens.
Figure 5 shows a small root fly emergence rate according to the treatment of Bacillus thuringiensis subspecies Zaponensis CAB452 strain. Bt CAB452: Bacillus thuringiensis subspecies zaponensis strain, Bt israelensis : Bacillus thuringiensis subspecies israelensis , control: untreated control.

In order to achieve the object of the present invention, in the present invention, the accession number is KCTC 13878BP, and the Bacillus thuringiensis subspecies japonensis ( Bacillus thuringiensis subsp. japonensis ) CAB452 strain having insecticidal activity against small root flies ( Bradysia agrestis ) is used. to provide.

The Bacillus thuringiensis subsp. japonensis CAB452 strain isolated in the present invention is a strain having excellent insecticidal activity against a fly insect pest, especially a small root fly, and it is transferred to the Korea Research Institute of Bioscience and Biotechnology Biological Resource Center. It was deposited under the deposit number KCTC 13878BP on July 5, 2019.

The term "insecticidal activity" refers to the ability of a substance to increase the mortality rate or inhibit the growth rate of hygiene or crop pests.

The present invention also provides a Bacillus thuringiensis subsp. japonensis ( Bacillus thuringiensis subsp. japonensis ) CAB452 strain or a small root fly ( Bradysia agrestis ) comprising a culture solution of the strain as an active ingredient.

The term “composition” is intended to mean a combination of an active agent and another compound, such as a carrier or composition, that is inert (eg, detectable drug or label or liquid carrier) or active (eg, adjuvant).

The composition for insecticidal small root fly according to the present invention is a mixture of a surfactant, inorganic salts, adjuvants, binders and extenders in 5 to 90% by weight of Bacillus thuringiensis subspecies zaponensis CAB452 strain, a culture solution thereof or a dried product of the culture solution. It can be prepared as an insecticidal composition.

The surfactant is an amphiphilic material having a hydrophilic molecular group and a lipophilic molecular group in a molecule at the same time, and is a material that is understood to have excellent characteristics of cleaning power, dispersing power, emulsifying power, solubilizing power, wetting power, sterilizing power, foaming power and penetrating power. , It can be understood that the Bacillus thuringiensis subspecies zaponensis CAB452 strain in the pesticidal composition according to the present invention functions to hydrate, suspend, and disperse to effectively express a medicinal effect.

As the surfactant, sodium salts of sulfonates such as alkylbenzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate, lignin sulfonate, alkyl naphthalene sulfonate formalin condensate, polyoxyalkylene alkylphenyl sulfonate, or Sodium salt of sulfate such as calcium salt, alkyl sulfate, polyoxyalkylene alkyl sulfate, polyoxyalkylene alkylphenyl sulfate or sodium salt of succinate such as calcium salt, naphthalene sulfosuccinate, polyoxyalkylene succinate, or Anionic surfactants such as calcium salts, ethoxylated alkyl ethers, polyoxyalkylene alkylphenyl polymers, and nonionic surfactants such as polyalcohols may be used alone or in combination of two or more, all of which are exemplarily listed. It can be readily understood by those of ordinary skill in the art that surfactants other than these may be used as these.

The extender is used together with the surfactant to adsorb and separate the surfactant, and the surfactant, the drug efficacy enhancer, the Bacillus thuringiensis subspecies zaponensis CAB452 strain, the culture solution thereof, or the dried product of the culture solution together with BT (BT ) It acts as a material that forms the surface of the fine particles of the composition, and starch, soybean meal, bran, granular fiber, yuan, diatomaceous earth, zeolite, bentonite, talc, kaolin, pyrophilite, white carbon, etc. Can be used.

The binder serves to bind to each other, including an active ingredient, Bacillus thuringiensis subspecies Zaponensis CAB452, a culture solution thereof, or a dried product of the culture solution, and binds a drug efficacy enhancer, an extender, etc. to each other, water-soluble starch, dextrin, carboxymethylcellulose , Sodium polyacrylate, polyvinyl alcohol, gum arabic or xanthan gum may be used alone or in combination of two or more.

The pesticidal composition may be formulated in the form of granules, powders, liquid wettable powders, wettable powders, etc., but is not limited thereto, and a wettable powder is preferable. The formulated pesticide may be used by diluting 500 to 2,000 times, preferably about 1,000 times, in water before use.

The invention also Bacillus-to Lindsay N-Sys subspecies Zaporozhye norbornene sheath (Bacillus thuringiensis subsp. Japonensis) by spraying CAB452 strain or an effective amount of said strain culture solution for plant, soil or small root flies (Bradysia agrestis) habitat rootlets Paris (Bradysia agrestis ).

The term "effective amount" is an amount sufficient to produce a beneficial or desired result. An effective amount may be administered more than once.

In the control method of the present invention, the plant to which the Bacillus thuringiensis subspecies zaponensis CAB452 strain or a culture solution thereof can be applied is not particularly limited, and Chinese cabbage, cabbage, cucumber, radish, perilla, red pepper, coniferous lettuce ( Lettuce), strawberries, tomatoes, green onions, tobacco, mushrooms, etc., as well as on the surface of plants such as flowers or specialty crops, or on the soil in which these plants are growing, or on the surface of vegetables being grown and transported or stored. I can.

Hereinafter, the present invention will be described in detail by examples. However, the following examples are only illustrative of the present invention, and the contents of the present invention are not limited to the following examples.

Example 1. Bacillus thuringiensis ( B. thuringiensis ) Selection of strains

In order to select the Bacillus thuringiensis strain, an effective and environmentally safe biological control agent for controlling larvae of Bradysia agrestis Sasakawa, 50 strains stored in the biological pest control laboratory of Chungnam National University were used. The morphology of parasporal inclusions of the cultured strains was observed through a phase contrast microscope. Of the 50 strains, 12 strains did not form toxin protein crystals, and 28 strains were observed to form toxin protein crystals of the Bipyramidal type. In addition, 10 strains were observed to form Spherical type of toxin protein crystals known to be active in the order Flies (Table 1).

Morphological classification of toxin protein crystals of isolated Bacillus thuringiensis strains Morphological features Bacillus thuringiensis strain number No crystal formation 12 Bipyramidal 28 Spherical 10 Sum 50

Ten strains forming spherical type of toxin protein crystals were selected, and insecticidal activity tests were performed on small root flies, which are the black winged mushroom flies, and the white stalk mosquito. As a result, of the 10 strains, Bacillus thuringiensis CAB463 and CAB467 strains had little insecticidal effect on small root flies. Bacillus thuringiensis CAB452 strain showed 90% or more high insecticidal activity against small root flies, and Bacillus thuringiensis CAB117, CAB469 and CAB599 strains showed more than 70% insecticidal activity, and Bacillus thuringiensis subspecies Israellensis ( B. thuringiensis subsp. israelensis ), Bacillus thuringiensis subspecies Molysoni ( B. thuringiensis subsp. morrisoni ) PG-14 and Bacillus thuringiensis CAB459, CAB462, CAB490 and CAB492 strains exhibited insecticidal activity of 50% or more. Regarding the mosquito, Bacillus thuringiensis subspecies Israelensis, Bacillus thuringiensis subspecies Molysoni PG-14 strains and Bacillus thuringiensis strains CAB117, CAB452, and CAB599 exhibited high insecticidal activity of more than 90% (Table 2). . Therefore, the CAB452 strain, which showed more than 90% insecticidal activity in both small root flies and white leaf mosquito, was finally selected.

Insecticidal activity against small root flies and mosquitoes strain Insecticide rate Small root fly Mosquito Bacillus Turingensys CAB117 ++ +++ Bacillus Turingensys CAB452 +++ +++ Bacillus Turingensys CAB459 + + Bacillus Turingensys CAB462 + - Bacillus Turingensys CAB463 - - Bacillus Turingensys CAB467 - - Bacillus Turingensys CAB469 ++ - Bacillus Turingensys CAB490 + + Bacillus Turingensys CAB492 + - Bacillus Turingensys CAB599 ++ +++ Bacillus thuringiensis subspecies israelensis + +++ Bacillus thuringiensis subspecies Molysoni PG-14 + +++ Untreated control - -

+++: high effect, 90% insecticide rate, ++: effective, 70-89% insecticide rate

+: Low effect, 50-69% insecticide rate, -: No effect, 0-49% insecticide rate

Example 2. Bioactivity assay

Bacillus thuringiensis CAB452 strain, which has an insecticidal activity of more than 90% against the small root flies of the P. black winged mushroom family, and the white leaf mosquito, the family P. mosquito, was selected, and the Bacillus thuringiensis subspecies Israel lances ( B. thuringiensis subsp. israelensis ) strain and B. thuringiensis subsp. morrisoni ) PG-14 strain were tested for insecticidal activity. As a result, the LC ₉₅ (lethal concentration 95% of test insect die) value of Bacillus thuringiensis subspecies Israelrensis strain and Bacillus thuringiensis subspecies Molysoni PG-14 strain for small root flies was 10 ⁸ (cfu/ml). ) And above, LC ₉₅ of Bacillus thuringiensis subspecies Zaponensis CAB452 strain The value was 4.4×10 ⁷ (cfu/ml), which confirmed high insecticidal activity.

Insecticidal Activity of Bacillus thuringiensis Strain Against Small Root Flies strain Small root fly LC ₅₀ LC ₉₅ Bacillus Turingensys CAB452 2.3×10 ⁶ 4.4×10 ⁷ Bacillus thuringiensis subspecies israelensis 2.1×10 ⁸ >10 ⁸ Bacillus thuringiensis subspecies Molysoni PG-14 1.8×10 ⁸ >10 ⁸ Untreated control 0 0

The LC ₉₅ value for the white leaf mosquito was 4.2×10 ⁶ (cfu/ml) for Bacillus thuringiensis CAB452 strain, and 2.2× for Bacillus thuringiensis subspecies Israelrensis, Bacillus thuringiensis subspecies Molisony PG-14 strain. It was identified as 10 ⁵ (cfu/ml) and 5.1×10 ⁵ (cfu/ml), respectively.

Insecticidal activity of Bacillus thuringiensis strains against white-tail mosquito strain Mosquito LC ₅₀ LC ₉₅ Bacillus Turingensys CAB452 2.3×10 ⁵ 4.2×10 ⁶ Bacillus thuringiensis subspecies israelensis 2.4×10 ⁴ 2.2×10 ⁵ Bacillus thuringiensis subspecies Molysoni PG-14 7.5×10 ⁴ 5.1×10 ⁵ Untreated control 0 0

Bacillus thuringiensis CAB452 strain showed relatively low insecticidal activity with a LC ₉₅ value for the white mosquito. When the Bacillus thuringiensis CAB452 strain was not fed, the mid-length of the larvae mosquito was clearly visible and the body was transparent, whereas the third day after treatment with the CAB452 strain, the mid-intestine was cloudy and partially darkened and cloudy. It was confirmed that on the 7th day after treatment of Bacillus thuringiensis CAB452 strain, the middle intestine was not seen and the whole body turned black and died (FIG. 1). In addition, although experimental data were not presented, biological activities against Spodoptera exigua and Spodoptera litura were tested to confirm the activity range of Bacillus thuringiensis CAB452 strain. I didn't see it. The concentration was uniform to confirm the fast-acting effect of Bacillus thuringiensis CAB117 and CAB599 strains and Bacillus thuringiensis subspecies Israellensis strains, both of which have an insecticidal activity of 70% or more, against the final selected strains, and the order of Flies, small root flies and white leaf mosquitoes. As a result of bioassay, the final selected Bacillus thuringiensis subspecies Zaponensis CAB452 showed a sharp increase in insecticidal rate from Day 3 compared to Bacillus thuringiensis subspecies Zaponensis CAB452 strains and Bacillus thuringiensis subspecies Israellensis. It was shown that (Fig. 2). Bacillus thuringiensis CAB452 strain exhibited high insecticidal activity against both the small root flies and the white leaf mosquito, which are the pests of the Order of Flies, and can be expected as a suitable strain as a biological control agent.

Example 3. Morphological characteristics

In order to confirm the crystalline protein of Bacillus thuringiensis CAB452 strain having high insecticidal activity against the order of Flies, it was observed using a phase contrast microscope and a scanning electron microscope. As a result of observation with a phase contrast microscope, it was confirmed that the Bacillus thuringiensis CAB452 strain formed a Spherical type of crystalline protein known to have insecticidal activity against Flies. In addition, when observed with a scanning electron microscope, as observed with a phase contrast microscope, a Spherical type of crystal protein known to have insecticidal activity in the order of Flies was confirmed (FIG. 3).

In general, a crystalline protein made by Bacillus thuringiensis has a molecular weight between 25 and 140 kDa and is composed of δ-endotoxin. Among the three types of crystalline proteins formed by Bacillus thuringiensis, the spherical type, which is reported to be mainly active against Flies pests, has been reported to have a molecular weight of ~65kDa (Ibarra and Federici, 1986, J. Bacteriol. 165(2) ):527-533).

SDS-PAGE was performed to compare the endotoxin protein properties of Bacillus thuringiensis CAB452 strain and Bacillus thuringiensis subspecies Israelensis, which exhibited high insecticidal activity against small root flies and white leaf mosquitoes. Bacillus thuringiensis CAB452 strain confirmed a protein band having a size of about 150 kDa. In order to confirm the active toxin pattern of the parasporal inclusions produced by the two strains, trypsin, a digestive enzyme, and small root fly larvae were compared by treating the small root fly larvae grinding solution because the intestine cannot be separated due to their small size. (Fig. 4). In Bacillus thuringiensis CAB452 strain, it was found that the main protein band of 150kDa size was decomposed by trypsin, a digestive enzyme, and small root fly larvae, to form one major band with a protein of about 50kDa size.

Example 4. Bacillus thuringiensis CAB452 Identification of strains and Cry-type genes

For the identification of the finally selected Bacillus thuringiensis CAB452 strain, commissioned by Omicspia Co., Ltd. to create a library for sequencing with a size of 20 kb using PacBio sequencing technology, and error based on Illumina data using SMRT sequencing technology. Error correction was performed. Using the 16S rRNA gene sequence, the genome of the standard strain belonging to the lineage with high similarity was obtained from GenBank, and BT toxin information and sequence were secured from the Bacillus thuringiensis toxin naming database to analyze the gene related to BT ( Bacillus thuringiensis ) toxicity. . In addition, the information of the BT toxin gene was confirmed and verified using the BLAST algorithm. As a result of the identification based on the sequence of the flagellin C gene at Mokwon University's Microbial Ecological Resources Research Institute, Bacillus thuringiensis The CAB452 strain showed a 98% similarity to the flagellin C gene sequence of the reference strain Bacillus thuringiensis subsp. japonensis BuiBui ( Bacillus thuringiensis subsp. japonensis BuiBui) (Table 5). Therefore, Bacillus thuringiensis subspecies japonensis ( B. thuringiensis subsp. japonensis ) Named.

In addition, the Bacillus thuringiensis subspecies zaponensis CAB452 strain had genes of cry9D1, cry9Eb1, Cry1B-like, cry1le1 and vip3Aa4 (Table 6), and the reference strain Bacillus thuringiensis subspecies zaponensis They had cry1le1 and vip3Aa4 genes that were not present in BuiBui .

Cry gene profile of Bacillus thuringiensis subspecies Zaponensis CAB452 strain strain Crystalline protein coding gene Bacillus thuringiensis subspecies Zaponensis CAB452 cry9D1, cry9Eb1, Cry1B-like, cry1le1 and vip3Aa4

Example 5. Bacillus thuringiensis subspecies Zaponensis CAB452 strain Control effect

In order to confirm whether the Bacillus thuringiensis subspecies Zaponensis CAB452 strain, selected through an indoor experiment, can be used in the actual field where small root flies occurred and the control effect, a pot experiment was performed in a greenhouse at Chungnam National University. Specifically, 100 small root fly larvae were inoculated into the pots transplanted with strawberries, and the final selected Bacillus thuringiensis subspecies Zaponensis CAB452 strain and the existing strain Bacillus thuringiensis subspecies Israelrensis strain were treated with root irrigation. Yellow sticky traps were installed in the upper and lower portions of the pot to investigate the number of adult worms that emerged before treatment and 7 and 14 days after treatment. It was repeated three times, and the temperature was 25±2℃, light condition 16L:8D, and relative humidity 50~60%. As a result of comparing the final selection of Bacillus thuringiensis subspecies Zaponensis CAB452 strain and the existing strain, Bacillus thuringiensis subspecies Israelensis strain treatment, the emergence rate (eclosion rate; the rate of pupae becoming a winged adult), Bacillus Turinensis subspecies Zaponensis When the culture medium of the CAB452 strain is 10 ⁷ (cfu/ml), the allergic rate is 68.8%, 10 ⁸ (cfu/ml) is 56.5%, and 10 ⁹ (cfu/ml) is 25.6%. It was confirmed that it was lost. On the other hand, the allegory rate of Bacillus thuringiensis subspecies Israellensis strain was 97.6%, and Bacillus thuringiensis subspecies Zaponensis. When treated with CAB452 strain, it was confirmed that the emergence rate was significantly reduced. As a result of obtaining control based on the allegory rate, Bacillus thuringiensis subspecies Zaponensis When treated with CAB452 strain (10 ⁹ cfu/ml) showed 74.3% control, whereas when treated with Bacillus thuringiensis subspecies Israelrensis strain, the control was 2.4%, which was very low (Table 7). ).

Bacillus thuringiensis subspecies zaponensis against small root fly larvae Control of strain CAB452 strain Treatment concentration (cfu/ml) Control (%) Bacillus thuringiensis subspecies Zaponensis CAB452
10 ⁷ 33 10 ⁸ 43.4 10 ⁹ 74.3 Bacillus thuringiensis subspecies israelensis 10 ⁸ 2.4 Untreated control 0 0

Korea Research Institute of Bioscience and Biotechnology KCTC13878BP 20190705

Claims (3)

Accession number is KCTC 13878BP, Bacillus thuringiensis subspecies japonensis ( Bacillus thuringiensis subsp. japonensis ) CAB452 strain having insecticidal activity against small root flies ( Bradysia agrestis ). A small root fly ( Bradysia agrestis ) insecticidal composition comprising the strain of claim 1 or a culture solution thereof as an active ingredient. A method of controlling small root flies ( Bradysia agrestis ) by spraying an effective amount of the strain of claim 1 or a culture solution thereof to plants, soil or small root flies ( Bradysia agrestis ) habitat.

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