A method for enhancing the biological activity of bacillus thuringiensis formulations using organic acids

Abstract

The present application relates to a kind of methods for improving the biological activity of Bacillus thuringiensis preparation using organic acid.The method is specifically as follows: adding organic acid to Bacillus thuringiensis preparation, thereby improving the biological activity of 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 includes any one or more of biofilm formation ability, ultraviolet resistance and insecticidal activity.By the method of the present application, the application effect of Bacillus thuringiensis preparation in agriculture can be significantly improved, and has high practical application value.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticides, and particularly relates to a method for enhancing the biological activity of a Bacillus thuringiensis preparation by utilizing organic acids. 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 showing significant insecticidal effects on pests such as Lepidoptera, Diptera and Coleoptera. Since France first launched a Bt product called Sporeine 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 will significantly affect the toxicity of Bt crystal toxins to pests, limiting its long-term effectiveness in agriculture.

[0003] Researchers have discovered that the addition of specific organic acids can significantly enhance the stability and bioactivity of Bt formulations. These organic acids, including palmitic acid, stearic acid, arachidic acid, acetylsalicylic acid, and oleic acid, improve Bt formulations' UV resistance and promote biofilm formation, thereby enhancing Bt's pest control effectiveness. Specifically, the addition of these organic acids can enhance the stability of Bt formulations under UV irradiation, extend their shelf life, and increase their toxicity to target pests in the environment.

[0004] Organic acids play a crucial role in biofilm formation. Biofilm formation aids microbial survival and reproduction in harsh environments and is crucial for improving their stress tolerance and activity. In agriculture and environmental protection, beneficial biofilms are widely used in biocontrol of plant pathogens, biofertilizers, pollutant degradation, and wastewater treatment. Therefore, using organic acids to promote biofilm formation in Bt formulations can not only enhance their resistance to UV rays but also improve their effectiveness in plant protection applications.

[0005] In agriculture, biofilms play a crucial role. Many beneficial microorganisms, particularly bacteria and fungi used as biopesticides, utilize biofilm formation to enhance their stability on plant surfaces or in soil. These biofilms can slow the degradation of microorganisms in the environment and improve their ability to adhere to plants, thereby enhancing their effectiveness in controlling pests and diseases, and promoting plant growth. Therefore, the formation of bacterial biofilms not only improves the stability of Bt formulations but also effectively enhances their effectiveness in plant protection applications.

[0006] The diamondback moth (Plutella xylostella) is a pest that poses a serious threat to cruciferous crops. Its high productivity and wide adaptability have made it one of the most challenging pests in global agriculture. Plutella xylostella has developed significant resistance to chemical insecticides, and the effectiveness of traditional chemical control methods has gradually decreased. Consequently, increasing research is focused on developing harmless alternatives, among which the use of Bt as a biopesticide to control Plutella xylostella has become an effective alternative. By optimizing the stability and activity of Bt formulations, especially by adding the aforementioned organic acids, their effectiveness against pests such as Plutella xylostella 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 enhancing the biological activity of a Bacillus thuringiensis preparation by utilizing organic acids.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for enhancing the biological activity of a Bacillus thuringiensis preparation using an organic acid: the organic acid is added to the Bacillus thuringiensis preparation, thereby enhancing 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;

[0010] 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, thereby enhancing the insecticidal activity of the Bacillus thuringiensis wettable powder;

[0011] Furthermore, after adding organic acids to the Bacillus thuringiensis preparation, it is necessary to co-cultivate under certain humidity and temperature conditions;

[0012] Furthermore, the Bacillus thuringiensis wettable powder was prepared with sterile water to a concentration of 5 g / L, and palmitic acid at a final concentration of 0.1 g / L or oleic acid at a final concentration of 0.2 g / L was added thereto, and co-cultured under certain humidity and temperature conditions to enhance the biofilm-forming ability of the Bacillus thuringiensis wettable powder.

[0013] 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, or stearic acid with a final concentration of 0.2 g / L, or arachidic acid with a final concentration of 0.05 g / L, or arachidic acid with a final concentration of 0.1 g / L, or acetylsalicylic acid with a final concentration of 0.2 g / L, or acetylsalicylic acid with a final concentration of 0.25 g / L, or 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 the mixture is co-cultured under certain humidity and temperature conditions, thereby improving the UV resistance of the Bacillus thuringiensis wettable powder;

[0014] 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 the mixture is co-cultured under certain humidity and temperature conditions to enhance the insecticidal activity of the Bacillus thuringiensis wettable powder.

[0015] The invention relates to the use of organic acids in enhancing the biological activity of a 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; and the biological activity includes any one or more of biofilm formation ability, UV resistance, and insecticidal activity.

[0016] The significant advantages of the present invention are:

[0017] 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 and 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, enabling it to maintain high biological activity under ultraviolet environmental pressure, thereby enhancing 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 broad application prospects, simple production process, low cost, easy to implement industrial production, and has good economic benefits and market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 : Concentration screening of Bacillus thuringiensis preparations.

[0019] Figure 2 : Effect of palmitic acid on the biofilm-forming ability of Bacillus thuringiensis preparations.

[0020] Figure 3 : Effect of stearic acid on the biofilm-forming ability of Bacillus thuringiensis preparations.

[0021] Figure 4 : Effects of arachidic acid on the biofilm-forming ability of Bacillus thuringiensis preparations.

[0022] Figure 5 : Effects of acetylsalicylic acid on the biofilm-forming ability of Bacillus thuringiensis preparations.

[0023] Figure 6 : Effect of oleic acid on biofilm formation ability of Bacillus thuringiensis preparations.

[0024] Figure 7 : Effect of palmitic acid on the UV resistance of Bacillus thuringiensis preparations.

[0025] Figure 8 : Effect of stearic acid on the UV resistance of Bacillus thuringiensis preparations.

[0026] Figure 9 : Effect of arachidic acid on the UV resistance of Bacillus thuringiensis preparations.

[0027] Figure 10 : Effect of acetylsalicylic acid on the anti-ultraviolet ability of Bacillus thuringiensis preparation.

[0028] Figure 11 : Effect of oleic acid on the UV resistance of Bacillus thuringiensis preparations. DETAILED DESCRIPTION

[0029] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0030] The Bacillus thuringiensis preparation involved in the embodiment of the present invention is specifically Bacillus thuringiensis 32000 IU / mg wettable powder, pesticide registration number PD20083182.

[0031] Example 1: Bacillus thuringiensis preparation concentration screening

[0032] The Bacillus thuringiensis preparation was prepared with sterile water to a concentration range of 1-10 g / L and cultured at a humidity of 52% and a temperature of 30°C for 48 hours. The amount of biofilm formed was determined after the culture was completed. The amount of biofilm formed was determined by crystal violet staining and the OD value was used. 595nm Indicates. OD595nm The larger the value, the higher the amount of biofilm formation.

[0033] The results show that ( Figure 1 ), 1-10 g / L Bacillus thuringiensis preparations were able to form biofilms; 5 g / L Bacillus thuringiensis preparation showed a strong biofilm-forming ability, so this concentration was selected as the representative concentration for subsequent experiments.

[0034] 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 formed was measured. The amount of biofilm formed was measured by crystal violet staining and OD 595nm Indicates. OD 595nm The larger the value, the higher the amount of biofilm formation.

[0035] 1) Effect of Palmitic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations: Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, to which palmitic acid was added at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L). The preparations were co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the co-culture. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L. The preparations were incubated at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the incubation.

[0036] 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.

[0037] 2) Effect of Stearic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations: Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, to which stearic acid at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L) was added. The cells were co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the co-culture. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L. The cells were co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the culture.

[0038] 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 biofilm formation of Bacillus thuringiensis preparations.

[0039] 3) Effect of Arachidic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations: Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, to which arachidic acid was added at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L). The preparations were co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the co-culture. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L. The preparations were incubated at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the incubation.

[0040] The results show that ( Figure 4 ), and arachidic acid at a final concentration of 0.05-0.25 g / L had no effect on increasing the biofilm formation of Bacillus thuringiensis preparations.

[0041] 4) Effect of Acetylsalicylic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations: Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, to which acetylsalicylic acid at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L) was added. The cells were co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the co-culture. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L. The cells were incubated at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the incubation.

[0042] 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 biofilm formation of Bacillus thuringiensis preparations.

[0043] 5) Effect of Oleic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations: Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, to which oleic acid was added at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L). The preparations were co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the co-culture. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L. The preparations were incubated at a humidity of 52% and a temperature of 30°C for 48 hours. The biofilm formation was measured after the incubation.

[0044] 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 Bacillus thuringiensis preparations.

[0045] Example 3: Effect of Organic Acids on the UV Resistance of Bacillus thuringiensis Preparations. Organic acids were added to a Bacillus thuringiensis preparation and incubated for 48 hours. Following incubation, the preparations were exposed to 254 nm ultraviolet light and the viability was measured to assess UV resistance. A higher viability indicates greater UV resistance.

[0046] 1) Effect of Palmitic Acid on the UV Resistance of Bacillus thuringiensis Preparations Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L. Palmitic acid was added at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L). The preparations were incubated at a humidity of 52% and a temperature of 30°C for 48 hours. After the incubation period, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their UV resistance. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L. The preparations were incubated at a humidity of 52% and a temperature of 30°C for 48 hours. After the incubation period, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their UV resistance.

[0047] 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.

[0048] 2) Effect of Stearic Acid on the Ultraviolet Resistance of Bacillus thuringiensis Preparations Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, to which stearic acid at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L) was added. The preparations were incubated at a humidity of 52% and a temperature of 30°C for 48 hours. After the incubation period, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their ultraviolet resistance. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, incubated at a humidity of 52% and a temperature of 30°C for 48 hours. After the incubation period, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their ultraviolet resistance.

[0049] 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.

[0050] 3) Effect of Arachidic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, to which arachidic acid at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L) was added. The preparations were co-cultured at a humidity of 52% and a temperature of 30°C for 48 hours. After co-culture, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their UV resistance. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, incubated at a humidity of 52% and a temperature of 30°C for 48 hours. After the incubation period, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their UV resistance.

[0051] The results show that ( Figure 9 ), arachidic acid with a final concentration of 0.05 g / L can significantly enhance the ability of Bacillus thuringiensis preparation 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 preparation 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 preparation to resist ultraviolet rays for 4 hours.

[0052] 4) Effect of Acetylsalicylic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, to which acetylsalicylic acid at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L) was added. The preparations were incubated at a humidity of 52% and a temperature of 30°C for 48 hours. After the incubation period, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their UV resistance. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, incubated at a humidity of 52% and a temperature of 30°C for 48 hours. After the incubation period, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their UV resistance.

[0053] The results show that ( Figure 10), acetylsalicylic acid with a final concentration of 0.10 g / L and 0.20 g / L can significantly improve the ability of Bacillus thuringiensis preparation to resist ultraviolet rays for 1 hour, acetylsalicylic acid with a final concentration of 0.10 g / L, 0.20 g / L and 0.25 g / L can significantly improve the ability of Bacillus thuringiensis preparation to resist ultraviolet rays for 2 hours, and 0.20 g / L can significantly improve the ability of Bacillus thuringiensis preparation to resist ultraviolet rays for 4 hours.

[0054] 5) Effect of Oleic Acid on the Biofilm Formation Ability of Bacillus thuringiensis Preparations Experimental Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, to which oleic acid was added at different final concentrations (0.05 g / L, 0.10 g / L, 0.20 g / L, and 0.25 g / L). The preparations were incubated at a humidity of 52% and a temperature of 30°C for 48 hours. After the incubation period, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their UV resistance. Control Group: Bacillus thuringiensis preparations were diluted with sterile water to a concentration of 5 g / L, incubated at a humidity of 52% and a temperature of 30°C for 48 hours. After the incubation period, the preparations were exposed to 254 nm ultraviolet light for different times (0 hour, 1 hour, 2 hours, and 4 hours). The viability of the cells was then measured to evaluate their UV resistance.

[0055] The results show that ( Figure 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 preparation 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 preparation 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 preparation to resist ultraviolet rays for 4 hours.

[0056] Example 4: Effect of organic acid on the insecticidal activity of Bacillus thuringiensis preparation Organic acid was added to the Bacillus thuringiensis preparation, which was then coated on diamondback moth feed for feeding diamondback moths. The mortality of the diamondback moths was counted after 16 hours of feeding.

[0057] 1) Effect of palmitic acid on the insecticidal activity of Bacillus thuringiensis preparations Experimental group:

[0058] A 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 preparation was then coated on a diamondback moth feed for feeding the diamondback moth. The mortality rate of the diamondback moth was counted after 16 hours of feeding to determine the insecticidal activity against the diamondback moth.

[0059] 2) Experimental group on the effect of stearic acid on the insecticidal activity of Bacillus thuringiensis preparations:

[0060] A 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 preparation was then coated on a diamondback moth feed for feeding the diamondback moth. The mortality rate of the diamondback moth was counted after 16 hours of feeding to determine the insecticidal activity against the diamondback moth.

[0061] 3) Experimental group on the effect of arachidic acid on the insecticidal activity of Bacillus thuringiensis preparations:

[0062] A 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 preparation was then applied to a diamondback moth feed for feeding to the diamondback moth. The mortality rate of the diamondback moth was counted after 16 hours of feeding to determine the insecticidal activity against the diamondback moth.

[0063] 4) Experimental group on the effect of acetylsalicylic acid on the insecticidal activity of Bacillus thuringiensis preparations:

[0064] A 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 preparation was then applied to a diamondback moth feed for feeding the moths. The mortality rate of the moths was counted after 16 hours of feeding to determine the insecticidal activity against the moths.

[0065] 5) Experimental group on the effect of oleic acid on the insecticidal activity of Bacillus thuringiensis preparations:

[0066] A 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 preparation was then applied to a diamondback moth feed for feeding the diamondback moth. The mortality rate of the diamondback moth was counted after 16 hours of feeding to determine the insecticidal activity against the diamondback moth.

[0067] 6) Control group:

[0068] The Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, and then applied to diamondback moth feed for feeding. The mortality of the diamondback moths was counted after 16 hours of feeding to determine the insecticidal activity against the diamondback moths.

[0069] 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 stearic acid (final concentration 0.20 g / L) treatment group 50The value was 0.275 g / L, which was 37% lower than that of the control group, showing a 1.58-fold enhanced insecticidal activity; the LC of the eicosanoid (final concentration 0.10 g / L) group 50 The 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 effect, 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.

[0070] Table 1 Effect of organic acid addition on insecticidal activity of Bacillus thuringiensis preparations

[0071]

[0072]

[0073] Example 5: Effect of organic acid addition on the insecticidal activity of Bacillus thuringiensis preparations after biofilm formation

[0074] Organic acids were added to the Bacillus thuringiensis preparation and co-cultured for 48 hours. The insecticidal activity was then determined after the co-culture period. The culture solution was spread on a diamondback moth feed and fed to the diamondback moths. The mortality rate of the diamondback moths was counted after 16 hours of feeding.

[0075] 1) Effect of palmitic acid on the insecticidal activity of Bacillus thuringiensis preparations Experimental group:

[0076] A 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.

[0077] 2) Experimental group on the effect of stearic acid on the insecticidal activity of Bacillus thuringiensis preparations:

[0078] A 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.

[0079] 3) Experimental group on the effect of arachidic acid on the insecticidal activity of Bacillus thuringiensis preparations:

[0080] A 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.

[0081] 4) Experimental group on the effect of acetylsalicylic acid on the insecticidal activity of Bacillus thuringiensis preparations:

[0082] A Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which acetylsalicylic acid was added to 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.

[0083] 5) Experimental group on the effect of oleic acid on the insecticidal activity of Bacillus thuringiensis preparations:

[0084] A Bacillus thuringiensis preparation was prepared with sterile water to a concentration of 5 g / L, to which oleic acid was added to 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.

[0085] 6) Control group:

[0086] 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 determined.

[0087] The results showed that adding different organic acids to the Bacillus thuringiensis preparation and co-culturing 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 efficacy was enhanced by 3.35-fold and 2.80-fold, respectively. Furthermore, the insecticidal efficacy of the arachidic acid, stearic acid, and oleic acid treatments also increased to varying degrees, by 1.57-fold, 1.73-fold, and 1.24-fold, respectively. This indicates that the biofilm formed after the addition of organic acids significantly enhanced the insecticidal ability of the Bacillus thuringiensis preparation.

[0088] Table 2 Effect of organic acid addition on insecticidal activity of Bacillus thuringiensis preparations after biofilm formation

[0089]

[0090] 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: 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.

2. The method according to claim 1, wherein: 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 then co-cultured under certain humidity and temperature conditions.

3. A method for enhancing the biological activity of a Bacillus thuringiensis preparation using organic acids, 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 0.1 g / L or oleic acid with a final concentration of 0.2 g / L is added thereto. The mixture is co-cultured under certain humidity and temperature conditions to enhance the biofilm-forming ability of the Bacillus thuringiensis wettable powder.

4. A method for enhancing the biological activity of a Bacillus thuringiensis preparation using organic acids, 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 the mixture is co-cultured under certain humidity and temperature conditions, thereby improving the ultraviolet resistance of the Bacillus thuringiensis wettable powder.

Images