Method for improving biological activity of bacillus thuringiensis preparation by using organic acid

Abstract

The invention relates to a method for improving biological activity of a bacillus thuringiensis preparation by using organic acid. The method specifically comprises the following steps: adding organic acid into a bacillus thuringiensis preparation so as to improve the biological activity of the bacillus thuringiensis preparation; the bacillus thuringiensis preparation is bacillus thuringiensis wettable powder; the organic acid is selected from any one or more of palmitic acid, stearic acid, arachidic acid, acetylsalicylic acid and oleic acid; the biological activity comprises any one or more of biofilm forming ability, anti-ultraviolet ability and insecticidal activity. By means of the method, the application effect of the bacillus thuringiensis preparation in agriculture can be remarkably improved, and the method has high practical application value.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticides, and in particular relates to a method for improving the biological activity of a Bacillus thuringiensis preparation by utilizing organic acid. Background Art

[0002] Bacillus thuringiensis (Bt) is one of the most widely used and successful insect pathogens in the world. The δ-endotoxin produced by Bt is a protein that is toxic to a variety of agricultural, forestry and sanitary pests, especially to pests such as Lepidoptera, Diptera and Coleoptera. Since the first Bt product named Sporeine was launched in France in 1938, the development and research of Bt products has continued to deepen. At present, Bt insecticides have occupied more than 90% of the global biopesticide market. However, although Bt has a wide range of insecticidal activity, its stability under natural environmental pressures such as ultraviolet (UV) radiation is poor. UV radiation is a known limiting factor that significantly affects the toxicity of Bt crystal toxins to pests, limiting its long-term effectiveness in agriculture.

[0003] The present invention has found that by adding some specific organic acids, the stability and biological activity of Bt preparations can be significantly enhanced. These organic acids include palmitic acid, stearic acid, arachidic acid, acetylsalicylic acid and oleic acid, which can improve the UV resistance of Bt preparations and promote the formation of biofilms, thereby improving the control effect of Bt on pests. Specifically, the addition of these organic acids can enhance the stability of Bt preparations under ultraviolet irradiation, extend their effective period, and increase their toxicity to target pests in the environment.

[0004] Organic acids play an important role in the formation of biofilms. The formation of biofilms helps microorganisms survive and reproduce in harsh environments, and is crucial to improving the stress resistance and activity of microorganisms. Especially in the fields of agriculture and environmental protection, beneficial biofilms are widely used in the fields of biological control of plant pathogens, biofertilizers, degradation of pollutants, and wastewater treatment. Therefore, the use of organic acids to promote the formation of biofilms by Bt preparations can not only enhance their resistance to ultraviolet rays, but also improve their application effect in plant protection.

[0005] In agriculture, the role of biofilms is particularly critical. Many beneficial microorganisms, especially bacteria and fungi used as biopesticides, use the formation of biofilms to enhance their stability on plant surfaces or in soil. These biofilms can delay the degradation of microorganisms in the environment and improve their ability to adhere to plants, thereby enhancing their effectiveness in controlling pests, resisting diseases and promoting plant growth. Therefore, the formation of bacterial biofilms can not only improve the stability of Bt preparations, but also effectively enhance their application effect in plant protection.

[0006] The diamondback moth (Plutellaxylostella) is a pest that poses a serious threat to cruciferous crops. With its high productivity and wide adaptability, it has become one of the most challenging pests in global agriculture. The diamondback moth has developed significant resistance to chemical insecticides, and the effectiveness of traditional chemical control methods has gradually weakened. Therefore, more and more research is focused on developing harmless alternatives, among which the use of Bt as a biological pesticide to control the diamondback moth has become an effective alternative. By optimizing the stability and activity of Bt preparations, especially by adding the above-mentioned organic acids, its control effect on pests such as the diamondback moth can be significantly improved, providing a new solution for green agriculture. Summary of the invention

[0007] The object of the present invention is to provide a method for improving the biological activity of Bacillus thuringiensis preparation by utilizing organic acid.

[0008] To achieve the above object, the present invention adopts the following technical solutions: A method for improving the biological activity of a Bacillus thuringiensis preparation by using an organic acid: adding an organic acid to the Bacillus thuringiensis preparation to improve the biological activity of the Bacillus thuringiensis preparation; the Bacillus thuringiensis preparation is a Bacillus thuringiensis wettable powder; the organic acid is selected from any one or more of palmitic acid, stearic acid, arachidic acid, acetylsalicylic acid, and oleic acid; the biological activity includes any one or more of biofilm formation ability, UV resistance, and insecticidal activity; Further, the Bacillus thuringiensis wettable powder is prepared with sterile water to a concentration of 5 g / L, and palmitic acid with a final concentration of 0.10 g / L, stearic acid with a final concentration of 0.20 g / L, arachidic acid with a final concentration of 0.10 g / L, acetylsalicylic acid with a final concentration of 0.05 g / L, or oleic acid with a final concentration of 0.10 g / L is added thereto, thereby improving the insecticidal activity of the Bacillus thuringiensis wettable powder; Furthermore, after adding organic acid to the Bacillus thuringiensis preparation, it is necessary to co-cultivate under certain humidity and temperature conditions; Furthermore, the Bacillus thuringiensis wettable powder is prepared with sterile water to a concentration of 5 g / L, palmitic acid with a final concentration of 0.1 g / L or oleic acid with a final concentration of 0.2 g / L is added thereto, and co-cultured under certain humidity and temperature conditions, thereby improving the biofilm formation ability of the Bacillus thuringiensis wettable powder; Furthermore, the Bacillus thuringiensis wettable powder is prepared with sterile water to a concentration of 5 g / L, and palmitic acid with a final concentration of 0.05 g / L, stearic acid with a final concentration of 0.2 g / L, arachidic acid with a final concentration of 0.05 g / L, arachidic acid with a final concentration of 0.1 g / L, arachidic acid with a final concentration of 0.25 g / L, acetylsalicylic acid with a final concentration of 0.1 g / L, acetylsalicylic acid with a final concentration of 0.2 g / L, acetylsalicylic acid with a final concentration of 0.25 g / L, oleic acid with a final concentration of 0.05 g / L, or oleic acid with a final concentration of 0.25 g / L is added thereto, and co-cultured under certain humidity and temperature conditions, thereby improving the UV resistance of the Bacillus thuringiensis wettable powder; Furthermore, the Bacillus thuringiensis wettable powder is prepared with sterile water to a concentration of 5 g / L, and palmitic acid with a final concentration of 0.10 g / L, stearic acid with a final concentration of 0.20 g / L, arachidic acid with a final concentration of 0.10 g / L, acetylsalicylic acid with a final concentration of 0.05 g / L, or oleic acid with a final concentration of 0.10 g / L is added thereto, and co-cultured under certain humidity and temperature conditions to enhance the insecticidal activity of the Bacillus thuringiensis wettable powder.

[0009] The application of organic acid in improving the biological activity of Bacillus thuringiensis preparation, wherein the Bacillus thuringiensis preparation is a Bacillus thuringiensis wettable powder; the organic acid is selected from any one or more of palmitic acid, stearic acid, arachidic acid, acetylsalicylic acid, and oleic acid; the biological activity includes any one or more of biofilm formation ability, UV resistance, and insecticidal activity.

[0010] The significant advantages of the present invention are: The present invention significantly improves the biological activity of the preparation by adding specific organic acids to the Bacillus thuringiensis preparation. Adding organic acids not only enhances the formation of biofilms, improves the viability of microorganisms in harsh environments, but also effectively prolongs the shelf life of the preparation under ultraviolet irradiation, thereby improving its stability in long-term applications. In addition, the present invention improves the stress resistance of Bacillus thuringiensis, enables it to maintain high biological activity under ultraviolet environmental pressure, and enhances its control effect on lepidopteran pests (such as diamondback moth). The greatest advantage of this method is that it provides a green and environmentally friendly alternative, reduces dependence on chemical pesticides, and meets the needs of current agricultural green development. At the same time, the present invention has a wide range of application prospects, simple production process, low cost, easy to achieve industrial production, and has good economic benefits and market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 : Concentration screening of Bacillus thuringiensis preparations.

[0012] Figure 2: Effect of palmitic acid on biofilm-forming ability of Bacillus thuringiensis preparations.

[0013] Figure 3 : Effect of stearic acid on biofilm formation ability of Bacillus thuringiensis preparations.

[0014] Figure 4 : Effect of arachidic acid on biofilm-forming ability of Bacillus thuringiensis preparations.

[0015] Figure 5 : Effect of acetylsalicylic acid on biofilm-forming ability of Bacillus thuringiensis preparations.

[0016] Figure 6 : Effect of oleic acid on biofilm-forming ability of Bacillus thuringiensis preparations.

[0017] Figure 7 : Effect of palmitic acid on the UV resistance of Bacillus thuringiensis preparations.

[0018] Figure 8 : Effect of stearic acid on the UV resistance of Bacillus thuringiensis preparations.

[0019] Fig. 9 : Effect of arachidic acid on the UV resistance of Bacillus thuringiensis preparations.

[0020] Fig.10 : Effect of acetylsalicylic acid on the UV resistance of Bacillus thuringiensis preparations.

[0021] Fig.11 : Effect of oleic acid on the UV resistance of Bacillus thuringiensis preparations. DETAILED DESCRIPTION

[0022] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0023] The Bacillus thuringiensis preparation involved in the embodiment of the present invention is specifically Bacillus thuringiensis 32000 IU / mg wettable powder, and its pesticide registration number is PD20083182.

[0024] Example 1: Bacillus thuringiensis preparation concentration screening The Bacillus thuringiensis preparation was prepared with sterile water to a concentration range of 1 to 10 g / L and cultured at a humidity of 52% and a temperature of 30°C for 48 hours. The amount of biofilm formation was measured after the culture was completed. The amount of biofilm formation was measured by crystal violet staining and OD 595nm Indicates. OD 595nm The larger the value, the higher the amount of biofilm formation.

[0025] The results show that Figure 1 ), 1-10 g / L Bacillus thuringiensis preparations were able to form biofilms; 5 g / L Bacillus thuringiensis preparations showed a strong biofilm-forming ability, so this concentration was selected as the representative concentration for subsequent experiments.

[0026] Example 2: Effect of organic acid on biofilm formation ability of Bacillus thuringiensis preparation Organic acid was added to the Bacillus thuringiensis preparation and co-cultured for 48 hours. After the co-culture, the amount of biofilm formation was measured. The amount of biofilm formation was measured by crystal violet staining method and OD 595nm Indicates. OD 595nm The larger the value, the higher the amount of biofilm formation.

[0027] 1) Effect of palmitic acid on biofilm formation ability of Bacillus thuringiensis preparation Experimental group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and palmitic acid of different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, 0.25 g / L) was added thereto, and co-cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the co-culture, the amount of biofilm formation was measured. Control group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the culture, the amount of biofilm formation was measured.

[0028] The results show that Figure 2 ), palmitic acid with a final concentration of 0.10 g / L can increase the biofilm formation of Bacillus thuringiensis preparation to a certain extent.

[0029] 2) Effect of stearic acid on the biofilm formation ability of Bacillus thuringiensis preparations Experimental group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and stearic acid of different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, 0.25 g / L) was added thereto, and co-cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the co-culture, the amount of biofilm formation was measured. Control group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the culture, the amount of biofilm formation was measured.

[0030] The results show that Figure 3 ), stearic acid at a final concentration of 0.05-0.25 g / L had no effect on increasing the amount of biofilm formed by Bacillus thuringiensis preparations.

[0031] 3) Effect of Arachidic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations Experimental group: The Bacillus thuringiensis preparations were prepared with sterile water to a concentration of 5 g / L, and different final concentrations of arachidic acid (0.05 g / L, 0.10 g / L, 0.20 g / L, 0.25 g / L) were added thereto, and co-cultured for 48 hours at a humidity of 52% and a temperature of 30°C. After the co-culture, the amount of biofilm formation was measured. Control group: The Bacillus thuringiensis preparations were prepared with sterile water to a concentration of 5 g / L, and cultured for 48 hours at a humidity of 52% and a temperature of 30°C. After the culture, the amount of biofilm formation was measured.

[0032] The results show that Figure 4 ), the final concentration of 0.05-0.25 g / L of arachidic acid had no effect on increasing the amount of biofilm formed by Bacillus thuringiensis preparations.

[0033] 4) Effect of acetylsalicylic acid on biofilm formation ability of Bacillus thuringiensis preparation Experimental group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, acetylsalicylic acid of different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, 0.25 g / L) was added thereto, and co-cultured for 48 hours at a humidity of 52% and a temperature of 30°C. After the co-culture, the amount of biofilm formation was measured. Control group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and cultured for 48 hours at a humidity of 52% and a temperature of 30°C. After the culture, the amount of biofilm formation was measured.

[0034] The results show that Figure 5 ), acetylsalicylic acid at a final concentration of 0.05-0.25 g / L had no effect on increasing the amount of biofilm formed by Bacillus thuringiensis preparations.

[0035] 5) Effect of oleic acid on biofilm formation ability of Bacillus thuringiensis preparation Experimental group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and oleic acid of different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, 0.25 g / L) was added thereto, and co-cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the co-culture, the amount of biofilm formation was measured. Control group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the culture, the amount of biofilm formation was measured.

[0036] The results show that Figure 6 ), oleic acid with a final concentration of 0.20 g / L significantly increased the amount of biofilm formed by the Bacillus thuringiensis preparation.

[0037] Example 3: Effect of organic acid on the anti-ultraviolet ability of Bacillus thuringiensis preparation Organic acid was added to the Bacillus thuringiensis preparation, and co-cultured for 48 hours. After the co-culture, it was exposed to 254nm wavelength ultraviolet light, and then its viable bacterial rate was measured to evaluate its anti-ultraviolet ability. The higher the viable bacterial rate, the stronger the anti-ultraviolet ability.

[0038] 1) Effect of palmitic acid on the anti-ultraviolet ability of Bacillus thuringiensis preparation Experimental group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5g / L, and palmitic acid of different final concentrations (0.05g / L, 0.10g / L, 0.20g / L, 0.25g / L) was added thereto, and co-cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the co-culture, it was exposed to 254nm wavelength ultraviolet light for different times (0 hours, 1 hour, 2 hours, 4 hours), and then its viable bacteria rate was measured to evaluate its anti-ultraviolet ability. Control group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5g / L, and cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the culture, it was exposed to 254nm wavelength ultraviolet light for different times (0 hours, 1 hour, 2 hours, 4 hours), and then its viable bacteria rate was measured to evaluate its anti-ultraviolet ability.

[0039] The results show that Figure 7 ), palmitic acid with a final concentration of 0.05 g / L can significantly enhance the ability of Bacillus thuringiensis preparation to resist ultraviolet rays for 4 h.

[0040] 2) Effect of stearic acid on the anti-ultraviolet ability of Bacillus thuringiensis preparation Experimental group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5g / L, and stearic acid of different final concentrations (0.05g / L, 0.10g / L, 0.20g / L, 0.25g / L) was added thereto, and co-cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the co-culture, it was exposed to 254nm wavelength ultraviolet light for different times (0 hours, 1 hour, 2 hours, 4 hours), and then its viable bacteria rate was measured to evaluate its anti-ultraviolet ability. Control group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5g / L, and cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the culture, it was exposed to 254nm wavelength ultraviolet light for different times (0 hours, 1 hour, 2 hours, 4 hours), and then its viable bacteria rate was measured to evaluate its anti-ultraviolet ability.

[0041] The results show that Figure 8 ), stearic acid with a final concentration of 0.20 g / L can significantly enhance the ability of Bacillus thuringiensis preparation to resist ultraviolet rays for 2 h.

[0042] 3) Effect of Arachidic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations Experimental group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and different final concentrations of arachidic acid (0.05 g / L, 0.10 g / L, 0.20 g / L, 0.25 g / L) were added thereto, and co-cultured for 48 hours under the conditions of 52% humidity and 30°C. After the co-culture, it was exposed to 254 nm wavelength ultraviolet light for different times (0 hours, 1 hour, 2 hours, 4 hours), and then its viable bacterial rate was measured to evaluate its anti-ultraviolet ability. Control group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and cultured for 48 hours under the conditions of 52% humidity and 30°C. After the culture, it was exposed to 254 nm wavelength ultraviolet light for different times (0 hours, 1 hour, 2 hours, 4 hours), and then its viable bacterial rate was measured to evaluate its anti-ultraviolet ability.

[0043] The results show that Fig. 9 ), arachidic acid with a final concentration of 0.05 g / L can significantly enhance the ability of Bacillus thuringiensis preparations to resist ultraviolet rays for 1 hour, arachidic acid with a final concentration of 0.05 g / L can significantly enhance the ability of Bacillus thuringiensis preparations to resist ultraviolet rays for 2 hours, arachidic acid with a final concentration of 0.05 g / L, 0.10 g / L and 0.25 g / L can significantly enhance the ability of Bacillus thuringiensis preparations to resist ultraviolet rays for 4 hours.

[0044] 4) Effect of acetylsalicylic acid on biofilm formation ability of Bacillus thuringiensis preparation Experimental group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and acetylsalicylic acid of different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, 0.25 g / L) was added thereto, and co-cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the co-culture, it was exposed to 254 nm wavelength ultraviolet light for different time periods (0 hour, 1 hour, 2 hours, 4 hours), and then its viable bacteria rate was measured to evaluate its anti-ultraviolet ability. Control group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the culture, it was exposed to 254 nm wavelength ultraviolet light for different time periods (0 hour, 1 hour, 2 hours, 4 hours), and then its viable bacteria rate was measured to evaluate its anti-ultraviolet ability.

[0045] The results show that Fig.10), acetylsalicylic acid with a final concentration of 0.10 g / L and acetylsalicylic acid with a final concentration of 0.20 g / L can significantly improve the ability of Bacillus thuringiensis preparations to resist ultraviolet rays for 1 hour, acetylsalicylic acid with a final concentration of 0.10 g / L, acetylsalicylic acid with a final concentration of 0.20 g / L and acetylsalicylic acid with a final concentration of 0.25 g / L can significantly improve the ability of Bacillus thuringiensis preparations to resist ultraviolet rays for 2 hours, and acetylsalicylic acid with a final concentration of 0.20 g / L can significantly improve the ability of Bacillus thuringiensis preparations to resist ultraviolet rays for 4 hours.

[0046] 5) Effect of oleic acid on biofilm formation ability of Bacillus thuringiensis preparation Experimental group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and oleic acid of different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, 0.25 g / L) was added thereto, and co-cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the co-culture, it was exposed to 254 nm wavelength ultraviolet light for different time periods (0 hour, 1 hour, 2 hours, 4 hours), and then its viable bacteria rate was measured to evaluate its anti-ultraviolet ability. Control group: Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and cultured for 48 hours under the conditions of humidity 52% and temperature 30°C. After the culture, it was exposed to 254 nm wavelength ultraviolet light for different time periods (0 hour, 1 hour, 2 hours, 4 hours), and then its viable bacteria rate was measured to evaluate its anti-ultraviolet ability.

[0047] The results show that Fig.11 ), oleic acid with a final concentration of 0.05 g / L and a final concentration of 0.25 g / L can significantly improve the ability of Bacillus thuringiensis preparations to resist ultraviolet rays for 1 hour, oleic acid with a final concentration of 0.05 g / L and a final concentration of 0.25 g / L can significantly improve the ability of Bacillus thuringiensis preparations to resist ultraviolet rays for 2 hours, and oleic acid with a final concentration of 0.25 g / L can significantly improve the ability of Bacillus thuringiensis preparations to resist ultraviolet rays for 4 hours.

[0048] Example 4: Effect of organic acid on insecticidal activity of Bacillus thuringiensis preparation Organic acid was added to the Bacillus thuringiensis preparation, and then coated on the diamondback moth feed for feeding the diamondback moth. After 16 hours of feeding, the mortality rate of the diamondback moth was counted.

[0049] 1) Effect of palmitic acid on the insecticidal activity of Bacillus thuringiensis preparations Experimental group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which palmitic acid was added at a final concentration of 0.10 g / L, and then coated on diamondback moth feed for feeding the diamondback moth. After 16 hours of feeding, the mortality rate of the diamondback moth was counted to determine the insecticidal activity against the diamondback moth.

[0050] 2) Experimental group on the effect of stearic acid on the insecticidal activity of Bacillus thuringiensis preparations: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which stearic acid was added at a final concentration of 0.20 g / L, and then coated on diamondback moth feed for feeding diamondback moth. The mortality rate of diamondback moth was counted after 16 hours of feeding to determine the insecticidal activity against diamondback moth.

[0051] 3) Experimental group on the effect of arachidic acid on the insecticidal activity of Bacillus thuringiensis preparations: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which arachidic acid was added at a final concentration of 0.10 g / L, and then coated on diamondback moth feed for feeding diamondback moth. The mortality rate of diamondback moth was counted after 16 hours of feeding to determine the insecticidal activity against diamondback moth.

[0052] 4) Experimental group on the effect of acetylsalicylic acid on the insecticidal activity of Bacillus thuringiensis preparations: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which acetylsalicylic acid was added at a final concentration of 0.05 g / L, and then applied on diamondback moth feed for feeding diamondback moth. The mortality rate of diamondback moth was counted after 16 hours of feeding to determine the insecticidal activity against diamondback moth.

[0053] 5) Experimental group on the effect of oleic acid on the insecticidal activity of Bacillus thuringiensis preparations: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which oleic acid was added at a final concentration of 0.10 g / L, and then applied on diamondback moth feed for feeding diamondback moth. The mortality rate of diamondback moth was counted after 16 hours of feeding to determine the insecticidal activity against diamondback moth.

[0054] 6) Control group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and then applied on a diamondback moth feed for feeding the diamondback moth. After 16 hours of feeding, the mortality rate of the diamondback moth was counted to determine the insecticidal activity against the diamondback moth.

[0055] The results showed (Table 1) that all treatments with organic acids showed significantly enhanced insecticidal activity compared to the control group. Specifically, the LC of the palmitic acid (final concentration 0.10 g / L) treatment group 50 The value was 0.273 g / L, which was about 37% lower than that of the control group (0.434 g / L), and the insecticidal activity was enhanced by 1.59 times; the LC of the group treated with stearic acid (final concentration 0.20 g / L) 50 The value was 0.275 g / L, which was 37% lower than that of the control group, showing a 1.58-fold enhancement of insecticidal activity; the LC of the arachidic acid (final concentration 0.10 g / L) group 50The value was 0.262 g / L, which was about 40% lower than that of the control group, and the insecticidal activity was enhanced by 1.66 times; the acetylsalicylic acid (final concentration 0.05 g / L) treatment group showed the most significant performance, and its LC 50 The value dropped to 0.195 g / L, which was about 55% lower than that of the control group, and the insecticidal activity increased by 2.23 times; the LC of the oleic acid (final concentration 0.10 g / L) treatment group 50 The value was 0.222 g / L, which was about 49% lower than that of the control group, and the insecticidal activity was enhanced by 1.96 times.

[0056] Table 1 Effect of organic acid addition on insecticidal activity of Bacillus thuringiensis preparations Example 5: Effect of organic acid addition on insecticidal activity of Bacillus thuringiensis preparations after biofilm formation Organic acid was added to the Bacillus thuringiensis preparation and co-cultured for 48 hours. After the co-culture, the insecticidal activity was determined: the culture solution was spread on a diamondback moth feed for feeding the diamondback moth, and the mortality rate of the diamondback moth was counted after 16 hours of feeding.

[0057] 1) Effect of palmitic acid on the insecticidal activity of Bacillus thuringiensis preparations Experimental group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which palmitic acid was added at a final concentration of 0.10 g / L. The mixture was co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. After the co-culture, the insecticidal activity against Plutella xylostella was determined.

[0058] 2) Experimental group on the effect of stearic acid on the insecticidal activity of Bacillus thuringiensis preparations: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which stearic acid was added at a final concentration of 0.20 g / L. The mixture was co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. After the co-culture, the insecticidal activity against Plutella xylostella was determined.

[0059] 3) Experimental group on the effect of arachidic acid on the insecticidal activity of Bacillus thuringiensis preparations: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which arachidic acid was added at a final concentration of 0.10 g / L. The mixture was co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. After the co-culture, the insecticidal activity against Plutella xylostella was determined.

[0060] 4) Experimental group on the effect of acetylsalicylic acid on the insecticidal activity of Bacillus thuringiensis preparations: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which acetylsalicylic acid was added at a final concentration of 0.05 g / L. The mixture was co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. After the co-culture, the insecticidal activity against Plutella xylostella was determined.

[0061] 5) Experimental group on the effect of oleic acid on the insecticidal activity of Bacillus thuringiensis preparations: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which oleic acid was added at a final concentration of 0.10 g / L. The mixture was co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. After the co-culture, the insecticidal activity against Plutella xylostella was measured.

[0062] 6) Control group: The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and cultured at a humidity of 52% and a temperature of 30° C. for 48 hours. After the culture, the insecticidal activity against Plutella xylostella was measured.

[0063] The results (Table 2) showed that the addition of different organic acids to the Bacillus thuringiensis preparation after co-cultivation for 48 hours significantly improved its insecticidal activity against Plutella xylostella. Compared with the control group, the LC 50 The values ​​were significantly reduced, and the insecticidal effects were enhanced by 3.35 times and 2.80 times, respectively. In addition, the insecticidal effects of the arachidic acid, stearic acid, and oleic acid treatment groups were also improved to varying degrees, by 1.57 times, 1.73 times, and 1.24 times, respectively. This shows that the biofilm formed after the addition of organic acids significantly enhanced the insecticidal ability of the Bacillus thuringiensis preparation.

[0064] Table 2 Effect of organic acid addition on insecticidal activity of Bacillus thuringiensis preparations after biofilm formation The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for enhancing the biological activity of a Bacillus thuringiensis preparation using organic acids, characterized in that: An organic acid is added to a Bacillus thuringiensis preparation to enhance the biological activity of the Bacillus thuringiensis preparation; the Bacillus thuringiensis preparation is a Bacillus thuringiensis wettable powder; the organic acid is selected from any one or more of palmitic acid, stearic acid, arachidic acid, acetylsalicylic acid, and oleic acid; the biological activity includes any one or more of biofilm formation ability, UV resistance, and insecticidal activity.

2. The method according to claim 1, characterized in that: Bacillus thuringiensis wettable powder is prepared with sterile water to a concentration of 5 g / L, and palmitic acid with a final concentration of 0.10 g / L, stearic acid with a final concentration of 0.20 g / L, arachidic acid with a final concentration of 0.10 g / L, acetylsalicylic acid with a final concentration of 0.05 g / L, or oleic acid with a final concentration of 0.10 g / L is added thereto, thereby enhancing the insecticidal activity of the Bacillus thuringiensis wettable powder.

3. The method according to claim 1, characterized in that: After adding organic acids to the Bacillus thuringiensis preparation, it is necessary to co-cultivate under certain humidity and temperature conditions.

4. The method according to claim 3, characterized in that: Bacillus thuringiensis wettable powder is prepared with sterile water to a concentration of 5 g / L, palmitic acid with a final concentration of 0.1 g / L or oleic acid with a final concentration of 0.2 g / L is added thereto, and co-cultured under certain humidity and temperature conditions to enhance the biofilm-forming ability of the Bacillus thuringiensis wettable powder.

5. The method according to claim 3, characterized in that: The Bacillus thuringiensis wettable powder is prepared with sterile water to a concentration of 5 g / L, and palmitic acid with a final concentration of 0.05 g / L, stearic acid with a final concentration of 0.2 g / L, arachidic acid with a final concentration of 0.05 g / L, arachidic acid with a final concentration of 0.1 g / L, arachidic acid with a final concentration of 0.25 g / L, acetylsalicylic acid with a final concentration of 0.1 g / L, acetylsalicylic acid with a final concentration of 0.2 g / L, acetylsalicylic acid with a final concentration of 0.25 g / L, oleic acid with a final concentration of 0.05 g / L, or oleic acid with a final concentration of 0.25 g / L are added thereto, and co-culture is carried out under certain humidity and temperature conditions, thereby improving the UV resistance of the Bacillus thuringiensis wettable powder.

6. The method according to claim 3, characterized in that: Bacillus thuringiensis wettable powder is prepared with sterile water to a concentration of 5 g / L, and palmitic acid with a final concentration of 0.10 g / L, stearic acid with a final concentration of 0.20 g / L, arachidic acid with a final concentration of 0.10 g / L, acetylsalicylic acid with a final concentration of 0.05 g / L, or oleic acid with a final concentration of 0.10 g / L is added thereto, and co-cultured under certain humidity and temperature conditions to enhance the insecticidal activity of the Bacillus thuringiensis wettable powder.

7. The use of organic acids in improving the biological activity of Bacillus thuringiensis preparations, characterized in that: The Bacillus thuringiensis preparation is a Bacillus thuringiensis wettable powder; the organic acid is selected from any one or more of palmitic acid, stearic acid, arachidic acid, acetylsalicylic acid, and oleic acid; and the biological activity includes any one or more of biofilm formation ability, UV resistance, and insecticidal activity.

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