Screening of entomogenous fungi with high pathogenicity to prodenia litura and compound application of entomogenous fungi and thymol

Abstract

The invention discloses compound application of entomogenous fungi with high pathogenicity to prodenia litura and thymol. The compounded insecticide is prepared by combining a beauveria bassiana strain with the preservation number of GDMCC (China General Microbiological Culture Collection Center) NO: 65072 and thymol. The research on the compounding effect of thymol and beauveria bassiana shows that the compounded insecticide can show a remarkable synergistic effect, the prevention and treatment effect is improved, the use dosage of a single chemical pesticide is reduced, the environmental pollution is reduced, and the problems that the existing pesticide is easy to generate resistance, the pesticide effect is not obvious and the like are effectively solved.

Description

Technical Field

[0001] The invention relates to the field of plant protection, specifically to the field of biological control, and in particular to the biological control of Spodoptera litura. Background Art

[0002] Nowadays, with the rapid growth of the global population and the increasing demand for agricultural products, people are facing more severe challenges. The harm caused by agricultural pests has reduced the yield and quality of global food production. Pest control has become an important part of ensuring the quality of crops (Savary S, Willocquet L, Pethybridge SJ, Esker P, McRoberts N, Nelson A. The global burden of pathogens and pests on major food crops. Nat Ecol Evol. 2019 Mar; 3 (3): 430-439. doi: 10.1038 / s41559-018-0793-yIF: 13.9Q1 13.9q1b1. Epub 2019 Feb 4. PMID: 30718852.). Strengthening pest and disease control can effectively ensure high yield, stable yield and increased efficiency of crops. At present, the application of chemical pesticides is still the way to reduce the occurrence of pests and diseases. However, the large-scale use of chemical pesticides will bring many adverse effects. The harm caused by chemical agents to the environment is becoming more and more serious. The residues produced during the degradation process not only persist and transform in aquatic ecosystems, causing agricultural non-point source pollution in rivers and streams worldwide, threatening drinking water resources and aquatic ecosystems, but also persist for a long time on land, posing a potential danger to the environment (Tudi M, Daniel Ruan H, Wang L, Lyu J, Sadler R, Connell D, Chu C, Phung DT. Agriculture Development, Pesticide Application and Its Impact on the Environment. Int J Environ Res Public Health. 2021 Jan 27; 18(3): 1112. doi: 10.3390 / ijerph18031112. PMID: 33513796; PMCID: PMC7908628.). The toxicity of pesticides to fish, aquatic plants and aquatic invertebrates has also been reported (Li, H., Cheng, F., Wei, Y., Lydy, MJ, You, J., 2017. Global occurrence of pyrethroid insecticides in sediment and the associated toxicological effects on benthicin vertebrates: an overview. J. Hazard Mater. 324B, 258-271).Therefore, establishing a sustainable new plant protection system, seeking more efficient, environmentally friendly and safe pesticides, implementing the plant protection policy of "prevention first, integrated control", adhering to agricultural control as the main and biological control as the basis, and combining other control measures to carry out comprehensive pest control has become an inevitable requirement for the green development of agriculture and environmental friendliness (Lu Ziqi, Wang Jing, Zhang Zhen, Wang Jiaoyu, Sun Guocang, Lin Fucheng. Research progress of RNAi-based biological pesticides [J]. Journal of Zhejiang Agricultural Sciences, 2024, Vol. 36 (4): 968-977).

[0003] Entomogenous fungi are widely distributed in nature and are important insect pathogenic microorganisms for controlling agricultural pests. They are well-known worldwide for their variety, safety and effectiveness, long application period, no harm to natural enemies, difficulty in developing resistance, and rapid mass production. There are more than 800 species of entomogenous fungi in more than 100 genera, and 405 species have been reported in my country, including 215 species of fungi that parasitize insects, 80 species of Cordyceps, and 10 species of fungi that parasitize nematodes. (Liu Yanmei, Yang Hangyu, Zhang Zongzhou. Types and pathogenic mechanisms of insect pathogenic fungi [J]. Journal of Tianshui Normal University, 2009, 29(2): 40-43.; Li Yue, Jiang Chunjie, Zhao Yuying, et al. Application of insect pathogenic fungi in biological control of forest pests [J]. Plant Protection, 2016, 10(20): 10-24) Currently, the most widely used biological control fungi are green muscardine, Beauveria bassiana and Verticillium lecanii. In my country, the control effect of Beauveria bassiana in early spring and plum rain season against pine caterpillars can reach more than 90%. Its mixed use with chemical insecticides can improve the control effect. Qiu Guo Sen et al. used Beauveria bassiana mixed with other agents (diflubenzuron) to control Dendrolimus punctatus, with a control rate of more than 98% and a sustained effect. Spraying green muscardine with locusts or grasshoppers can achieve a mortality rate of 70%-90%, and is harmless to non-target pests. Verticillium lecanii can naturally parasitize aphids and scale insects. Li Guoxia et al. used it to control greenhouse vegetable aphids, with an effect of up to 93.1% (Yang Yunhua, Du Kaishu, Shi Mingwang. Research progress on biological control of entomogenous fungi [J]. Journal of Henan Institute of Science and Technology (Natural Science Edition), 2011, 39(01): 34-37.).

[0004] Spodoptera litura Fabricius belongs to the family Noctuidae in the order Lepidoptera. It is mainly distributed in the subtropical and temperate regions of Asia and Oceania, and is distributed in provinces in both the north and south of my country (Zhao Shengyuan, Luo Qianming, Sun Xiaoxu, et al. Comparison of morphological characteristics and biological learning of fall armyworm and fall armyworm [J]. China Plant Protection Guide, 2019, 39(5): 26–35.). It is a widely distributed, polyphagous pest that is distributed on more than 100 different host plants, including cotton, tobacco, tea, vegetables and other agricultural crops. The larvae have a polyphagous diet and a large appetite, showing the characteristics of intermittent outbreaks. If not controlled, it will seriously limit food production. It is an important pest that causes serious damage to crops and is difficult to control (Ahmad M, Iqbal Arif M, Ahmad M. Occurrence of insecticide resistance in field populations of Spodoptera litura (Lepidoptera: Noctuidae) in Pakistan [J]. Crop Protection, 2007, 26(6): 809–817.; Sun H, Shu Y, Tang W, et al. Nickel accumulation and its effects on the survival rate of Spodoptera liturafabricius under continuous nickel stress [J]. Chinese Science Bulletin, 2007, 52(14): 1957–1963.). Due to the serious overlap of generations and the wide host range of Spodoptera litura, people have long used various chemical agents to control it. This has made the pest resistant to organochlorine, organophosphate, carbamate, pyrethroid and Bt preparations (Wu Cunbing. Determination of insecticide resistance of Spodoptera litura in the Jianghuai region [J]. Anhui Agricultural Science (20): 5281-5282.), making control difficult. In addition, the frequent use of chemical pesticides has damaged the ecological environment and threatened human health. The biological control of Spodoptera litura has attracted more and more attention. Therefore, in today's world where it is extremely urgent to seek environmentally friendly control strategies, biological control has broad application prospects in pest control. In addition, biological control can ensure the quality and safety of products during the production process and effectively reduce the use of chemical agents.

[0005] So far, the academic community has accumulated a lot of research results on biological control strategies for the agricultural pest Spodoptera litura. Among them, Beauveria bassiana, as an insect pathogenic fungus with a wide host range, strong pathogenicity and high adaptability, has attracted the attention of many researchers at home and abroad. Its preparations have been widely used in agricultural and forestry pest control due to their unique advantages as microbial broad-spectrum insecticides. (Que Shengquan, Yu Ailin, Liu Yajun, Tu Yegou, Wang Xiaodong, Xiong Caiyun. Research progress on the application of Beauveria bassiana [J]. Chinese Journal of Forest Diseases and Insects, 2019, Vol. 38 (2): 29-35) In the 20th century, the first biological preparation with Beauveria bassiana as the main active ingredient was registered in the United States (FENG MG, POPRAWESKI TJ, KHACHATOURIANS GG, et al. Production, formulation and application of the entomopathogenic fungus Beauveria bassiana for insect control: current status [J]. Biocontrol Science and Technology, 1994, 4 (1): 3-34.), and then the research and development of various Beauveria bassiana preparations ushered in a period of vigorous development, and various products emerged in an endless stream. According to statistics, fungal insecticide preparations with Beauveria bassiana as the core ingredient currently account for 33.9% of all fungal insecticides worldwide. This data highlights the important position of Beauveria bassiana in the field of biological pesticide preparations. As my country's concept of green agriculture and ecological protection continues to deepen, the registration and application of microbial pesticides have also made significant progress. Among the 56 registered microbial pesticides, Beauveria bassiana accounts for 24 (Liu Jian, Chen Hongzhang, Li Zuohu. Research status and prospects of Beauveria bassiana insecticide production technology [J]. Chinese Journal of Biological Control, 2003, 19(2): 86-90.; Yan Tingting, Suo Lin. Application and discussion of microbial pesticides in organic agricultural production [J]. China Standardization, 2022, (2): 95-99). Biopesticides, especially microbial pesticides represented by Beauveria bassiana, play an increasingly prominent role in plant protection and ecological maintenance. They can not only effectively prevent and control pests and diseases and reduce dependence on chemical pesticides, but also promote biodiversity and maintain ecological balance. The role of biopesticides in plant protection and ecological maintenance is increasingly valued.

[0006] In general, botanical insecticides are considered safer than traditional insecticides due to their biodegradability. Plant essential oils are considered an important biological source for developing natural and environmentally safe pest control tools due to their multiple modes of action against insects. They have a variety of modes of action and low toxicity to mammals, birds and fish. Several recent studies have demonstrated the efficacy of essential oil compounds against lepidopteran insects. Thymol is a natural product known to have insecticidal activity against a variety of insects. It has been reported as an insecticide, acaricide and anthelmintic in agriculture (Kumrungsee N, Pluempanupat W, Koul O, Bullangpoti V. Toxicity of essential oil compounds against diamondback moth, Plutellaxylostella, and their impact on detoxifcation enzyme activities. J Pest Sci. 2014; 87: 721–9.8.; Nobsathian S, Saiyaithong C, Koul O, Pluempanupat W, Bullangpoti V, Kumrungsee N. The insecticidal potential of Piper ribesioides (Piperales: Piperaceae) extracts and isolated allelochemicals and their impact on the detoxifcation enzymes of Spodoptera exigua (Lepidoptera: Noctuidae). Phytoparasitica. 2021; 49: 659–73.; Kumrungsee N, Pluempanupat W, Koul O, Bullangpoti V, Kumrungsee N. The insecticidal potential of Piper ribesioides (Piperales: Piperaceae) extracts and isolated allelochemicals and their impact on the detoxifcation enzymes of Spodoptera exigua (Lepidoptera: Noctuidae). Phytoparasitica. 2021; 49: 659–73.; Kumrungsee N, Pluempanupat W, Koul O, Bullangpoti V, Kumrungsee N. O and Bullangpoti V,Toxicity of essential oil compoundsagainst diamondback moth,Plutellaxylostella,and their impact ondetoxification enzyme activities. J Pest Sci 87:721–729(2014).).

[0007] The insecticidal effect of entomogenous fungi is greatly affected by environmental factors, mainly temperature, humidity, etc., as well as other biological factors, such as the age and size of the host insects, living habits, etc. (Fernandes, EKK (Fernandes, Everton KK) 1; Rangel, DEN (Rangel, Drauzio EN) 2; Braga, GUL (Braga, Gilberto UL) 4,3; Roberts, DW (Roberts, Donald W.) 5. Tolerance of entomopathogenic fungi to ultraviolet radiation: a review on screening of strains and their formulation [J]. Current Genetics, 2015, Vol. 61 (3): 427-440). Based on the significant heterogeneity and high genetic diversity of wild-type Beauveria bassiana, strains from the same geographical and host sources show different virulence and biological characteristics, which makes it a basic challenge to screen highly virulent biocontrol strains and optimize their control strategies. At the same time, in practical applications, although Beauveria bassiana has shown good biological control potential, its insecticidal effect is poor due to factors such as slow insecticidal effect, great environmental impact, and unstable effect. In order to overcome these problems, thymol is combined with this biological pesticide, which has super high efficiency, low toxicity (the preparation is nearly non-toxic), low residue, and pollution-free characteristics against insects. By using the two together to control Spodoptera litura, the problem of slow effect of Beauveria bassiana can be overcome, and the development of pest resistance can be effectively delayed, thereby achieving good insecticidal effects and realizing more stable and efficient pest management. Summary of the invention

[0008] The purpose of the present invention is to develop a biological control of Spodoptera litura in tobacco fields in Guizhou Province, which is an important demand of agricultural production, and provide a strain of Beauveria bassiana with high toxicity to Spodoptera litura collected from tobacco fields in Taoxu Town, Jianghua County, Yongzhou City, Hunan Province. At the same time, a highly efficient, pollution-free, and residue-free insecticide for the combined use of thymol and Beauveria bassiana with synergistic effects is provided. The present invention studies the compounding effect of thymol and Beauveria bassiana and finds that the insecticide can show a significant synergistic effect after compounding, improves the control effect, and can significantly reduce the dosage of a single agent of chemical pesticides, reduce environmental pollution, and effectively solve the problems of existing pesticides being prone to resistance and having unclear efficacy.

[0009] The technical solution of the present invention is as follows:

[0010] The present invention is based on the fact that the screened Beauveria bassiana GZYKYJH20 has a certain biological control effect on Spodoptera litura (see Chinese patent application CN202411318580.9 for the specific screening process). After a large number of experiments, it was found that the combination of thymol and Beauveria bassiana GZYKYJH20 can produce a significant synergistic effect, and has a significant control effect on Spodoptera litura, thereby finally completing the present invention.

[0011] Therefore, the present invention provides an insecticide for controlling Spodoptera litura, which contains thymol and Beauveria bassiana as effective ingredients, and the preservation number of the Beauveria bassiana is GDMCC NO:65072.

[0012] Specifically, the Beauveria bassiana is in the form of a suspension or spore powder of Beauveria bassiana spores.

[0013] Preferably, the dosage ratio of Beauveria bassiana and thymol is: the final concentration of Beauveria bassiana is 1×10 5 ~1×10 9 Conidia / mL, preferably 1×10 7 ~1×10 8 conidia / mL, the final concentration of thymol is 1.0-4.0 mg / mL, preferably 2.0-4.0 mg / mL

[0014] More preferably, the ratio of Beauveria bassiana to thymol is 1×10 7 ~1×10 8 Conidia / mL: 0.05-0.5 mg / mL, preferably the ratio of Beauveria bassiana to thymol is 1×10 7 ~1×10 8 Conidia / mL: 0.08-0.12 mg / mL. Particularly preferably, the ratio of Beauveria bassiana to thymol is 1×10 8 Conidia / mL: 2.0 mg / mL.

[0015] The invention provides application of the insecticide in preventing and controlling Spodoptera litura.

[0016] The present invention also provides a method for controlling Spodoptera litura, which comprises applying the insecticide to crops or environments where Spodoptera litura needs to be controlled, preferably, applying the insecticide at the early stage of the emergence of Spodoptera litura.

[0017] Biomaterial preservation information: The Beauveria bassiana GZYKYJH20 involved in the present invention was deposited in the Guangdong Provincial Microbiological Culture Collection Center (address: 5th Floor, Building 59, No. 100 Xianlie Middle Road, Guangzhou City, Guangdong Province, China) on August 29, 2024, and its preservation number is GDMCC NO: 65072, and its classification name is: Beauveria bassiana. DETAILED DESCRIPTION

[0018] The following is an introduction through the research and development process and specific implementation methods of the present invention, but does not constitute a limitation of the present invention.

[0019] Test insects

[0020] The eggs of Spodoptera litura were purchased from Keyun Biological Co., Ltd. and were reared with artificial diet in an artificial climate chamber of the Engineering Research Center of Ministry of Education for Biological Control to form a population of Spodoptera litura. The rearing conditions were temperature (27±1)℃, photoperiod L14:D10, and relative humidity (75±5)%.

[0021] Experimental methods

[0022] 1. Compatibility study of Beauveria bassiana GZYKYJH20 and thymol and screening of combined dosage

[0023] 1) Effect of thymol on spore germination rate of strain GZYKYJH20

[0024] During the test, the strain to be tested was first transferred to a PDA plate and cultured at 26±1°C. After conidia were produced, the spores were washed with 0.05% Tween-80 sterile water, stirred with a magnetic stirrer, filtered, and counted by hemocytometer. The spores were then prepared into 1×10 6 spores / mL spore suspension for later use. Thymol original drug was dissolved in acetone to prepare a 10mg / mL agent for later use. Thymol was added to 50mL SDA liquid culture medium to prepare SDA liquid culture medium with thymol concentrations of 0.05, 0.25, 0.5, 1.0 and 2.0mg / mL. 2mL 1×10 6 Spores / mL spore suspension was added to the culture medium with different concentrations of thymol and placed in a shaker at 180rpm and 25℃. Samples were taken with a pipette at 24h, 48h and 72h, and the spore germination of each treatment was examined under a microscope on a hemocytometer to calculate the spore germination rate. Each treatment was repeated 3 times, and the liquid culture medium with sterile water was used as a blank control.

[0025] 2) Effect of thymol on mycelial growth of strain GZYKYJH20

[0026] During the test, thymol corresponding to the concentration of 2.5.1 was added to each PDA culture dish (7.5 cm in diameter), and the drug solution was evenly spread on the surface of the culture medium with a high-temperature sterilized triangular glass rod to make drug-containing PDA culture medium plates of different concentrations. Take a Beauveria bassiana culture dish with evenly distributed mycelium, punch a bacterial cake with a 5 mm diameter puncher on a clean bench, place the bacterial cake in the center of the drug-containing PDA plate for inoculation, and culture it in a 26±2℃ light incubator. Use the cross method to measure the colony diameter on the 3rd, 5th and 7th days, respectively, in mm. Each treatment was repeated 5 times, and the PDA culture medium with sterile water was used as a control.

[0027] 3) Toxicity test of strain GZYKYJH20 and thymol combination against Spodoptera litura

[0028] a. Toxicity test of thymol to the second instar larvae of Spodoptera litura

[0029] Use sterile water to prepare thymol agents at concentrations of 0.5, 1.0, 2.0, and 4.0 mg / ml. The remaining steps are the same as in 2.4.2. b. Toxicity test of the combination of strain GZYKYJH20 and thymol to the second-instar larvae of Spodoptera litura

[0030] According to the combination in Table 1, indoor toxicity test was carried out, and the experimental method and steps were the same as above.

[0031] Table 1. Combination of strain GZYKYJH20 and thymol

[0032] Processing agent number Strain GZYKYJH20 (spores / ml) Thymol (mg / mL) T1(CK) 0 0 T2 <![CDATA[1×10 7 ]]> 0 T3 <![CDATA[1×10 8 ]]> 0 T4 0 1.0 T5 0 2.0 T6 0 4.0 T7 <![CDATA[1×10 7 ]]> 1.0 T8 <![CDATA[1×10 7 ]]> 2.0 T9 <![CDATA[1×10 7 ]]> 4.0 T10 <![CDATA[1×10 8 ]]> 1.0 T11 <![CDATA[1×10 8 ]]> 2.0 T12 <![CDATA[1×10 8 ]]> 4.0

[0033] 4) Data statistics and analysis

[0034] SPSS 19.0 software was used to process and analyze the experimental data. One-way ANOVA was used to analyze the results of the mortality rate of the second-instar larvae of Spodoptera litura, and Tukey's test was used to test the significance of the difference. The data calculation formula was based on Huang et al. (2013), and the specific formula is as follows:

[0035] Me=Ma+Mb×(1-Ma)

[0036]

[0037] In the formula, the meanings of each item are as follows:

[0038] Ma: actual corrected mortality of thymol alone against second-instar larvae of Spodoptera litura;

[0039] Mb: actual corrected mortality of the highly virulent strain against the second-instar larvae of Spodoptera litura alone;

[0040] Mab: Actual corrected mortality of fungicide combination against second instar larvae of Spodoptera litura.

[0041] Experimental Results

[0042] 1. Effects of thymol on spore germination rate and mycelial growth of strain GZYKYJH20

[0043] The test results in Table 2 show that when treated for 24 hours, the spore germination rates of strain GZYKYJH20 in the treatment of 0.25, 0.5, and 1.0 mg / mL thymol concentrations were 98.15%, 96.46%, and 95.46%, respectively, which were not significantly different from the blank control (98.52%). After treatment with 2.0 mg / mL and 4.0 mg / mL thymol concentrations, the spore germination rates of strain GZYKYJH20 (93.19% and 88.43%) were significantly lower than those of the sterile water blank control (98.52%). And the difference was significant with the control group. When treated for 48 hours, the spore germination rates of strain GZYKYJH20 in the treatment of 0.25, 0.5, and 1.0 mg / mL thymol concentrations were 97.86%, 94.46%, and 96.11%, respectively, which were not significantly different from the sterile water blank control (98.87%). At 72h of treatment, the spore germination rates of strain GZYKYJH20 in the treatments of 0.25, 0.5, 1.0, 2.0 mg / mL thymol were 97.24%, 96.70%, 96.11%, and 96.01%, respectively, which were not significantly different from the blank control (98.18%). After treatment with 4.0 mg / mL thymol, the spore germination rate of strain GZYKYJH20 (94.26%) was significantly lower than that of the sterile water blank control (98.52%), which was significantly different from the control group.

[0044] The test results in Table 3 show that the colony diameters of strain GZYKYJH20 treated with thymol at concentrations of 0.25 mg / mL, 0.5 mg / mL, 1.0 mg / mL, 2.0 mg / mL and 4.0 mg / mL were 38.95 mm, 37.81 mm, 35.72 mm, 34.28 mm and 31.32 mm on the 7th day, which were significantly different from those of the blank control (39.6 mm).

[0045] The results showed that low and medium concentrations of thymol had good compatibility with Beauveria bassiana GZYKYJH20 and could be compounded in subsequent experiments and practical applications.

[0046] Table 2. Effects of Thymol on spore germination rate and mycelial growth of strain GZYKYJH20

[0047]

[0048] Note: According to Tukey test, different lowercase letters in the same column indicate significant differences in pathogenicity among different strains (P < 0.05).

[0049] 2. Toxicity test of strain GZYKYJH20 and thymol combination against Spodoptera litura

[0050] 1) Results of toxicity test of thymol against second-instar larvae of Spodoptera litura

[0051] The corrected mortality rates of the second-instar larvae of Spodoptera litura treated with different concentrations of thymol were different and the differences were significant (Table 3). As the concentration of thymol increased, the corrected mortality rate of the second-instar larvae of Spodoptera litura also increased. When the concentration of thymol was 0.5-4.0 mg / mL, the corrected mortality rate of the second-instar larvae of Spodoptera litura after treatment was 6.67%-50.57%.

[0052] Table 3. Effect of Thymol on the mortality of second-instar larvae of Spodoptera litura

[0053]

[0054] Note: According to Tukey test, different lowercase letters in the same row indicate significant differences in pathogenicity among different strains (P < 0.05)

[0055] 3. Results of toxicity test of strain GZYKYJH20 and thymol against the second-instar larvae of Spodoptera litura

[0056] The toxicity results of strain GZYKYJH20 and thymol on the second instar larvae of Spodoptera litura are shown in Table 4. The results showed that the corrected mortality rates of the second instar larvae of Spodoptera litura treated with different concentrations of thymol (1.0, 2.0, 4.0 mg / mL) were 35.11%, 44.51%, and 52.22% after the 5th day, respectively; the corrected mortality rates of the second instar larvae of Spodoptera litura treated with different concentrations of strain GZYKYJH20 (1×10 7 , 1×10 8 spores / mL) were used to treat the 2nd instar larvae of Spodoptera litura, and the corrected mortality rates on the 5th day were 43.67% and 54.46%, respectively.

[0057] The combination of different concentrations of thymol and different concentrations of strain GZYKYJH20 had a significantly higher lethality rate on the 5th day against the second-instar larvae of Spodoptera litura than the single agents. In the toxicity test of the combined action of thymol and strain GZYKYJH20 on the second-instar larvae of Spodoptera litura, the combination T7 (1×10 7 +1.0), T8(1×10 7 +2.0), T9(1×10 7 +4.0), T10(1×10 8 +1.0), T11(1×10 8 +2.0), T12(1×10 8+4.0) showed synergistic effects 3-5 days after treatment, with the highest corrected mortality rates of 85.37%, 91.33%, 100%, 93.57%, 100%, and 100%, respectively, and the differences were significant. These combinations all had good synergistic effects. Combined with the dosage and actual lethal effect, 1×10 8 The best combination was the mixture of spores / ml Beauveria bassiana GZYKYJH20 and 2.0 mg / mL thymol.

[0058] Table 4. Corrected mortality of the second instar larvae of Spodoptera litura caused by the synergistic effect of strain GZYKYJH20 and Thymol

[0059]

[0060]

[0061] Note: The data in the table are mean ± standard error. After Tukey test, different lowercase letters indicate significant differences between different combination concentrations at the same time (P < 0.05). The values ​​in brackets represent the expected mortality rate and the calculated chi-square value χ 2 , * indicates a combination with synergistic effect.

[0062] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention are included in the protection scope of the present invention.

Claims

1. An insecticide for controlling Spodoptera litura, characterized in that: The invention contains thymol and Beauveria bassiana as effective ingredients, and the preservation number of the Beauveria bassiana is GDMCC NO:65072.

2. The insecticide according to claim 1, characterized in that The Beauveria bassiana is in the form of a suspension or spore powder of Beauveria bassiana spores.

3. The insecticide according to claim 2, characterized in that The dosage ratio of Beauveria bassiana and thymol is: the final concentration of Beauveria bassiana is 1×10 5 ~1×10 9 Conidia / mL, preferably 1×10 7 ~1×10 8 conidia / mL, the final concentration of thymol is 1.0~4.0 mg / mL, preferably 2.0~4.0 mg / mL.

4. The insecticide according to claim 3, characterized in that The ratio of Beauveria bassiana to thymol is 1×10 7 ~1×10 8 Conidia / mL: 0.05~0.5 mg / mL, preferably the ratio of Beauveria bassiana to thymol is 1×10 7 ~1×10 8 Conidia / mL: 0.08~0.12 mg / mL.

5. The insecticide according to claim 4, characterized in that The ratio of Beauveria bassiana to thymol is 1×10 8 Conidia / mL: 2.0 mg / mL.

6. Use of the insecticide according to any one of claims 1 to 5 in controlling Spodoptera litura.

7. A method for controlling Spodoptera litura, characterized in that , applying the insecticide according to any one of claims 1 to 5 to crops or environments that need to control Spodoptera litura.

8. The method according to claim 7, characterized in that Apply at the early stage of Spodoptera litura emergence.

Images