Green prevention and control method for cassava tetranychus cinnabarinus based on immune induced resistance

Abstract

The invention belongs to the technical field of tetranychus cinnabarinus prevention and control, and particularly relates to a cassava tetranychus cinnabarinus green prevention and control method based on immune induced resistance. The method is realized by spraying a methyl salicylate composite agent in the cassava planting process or when tetranychus cinnabarinus diseases occur. The active component of the pesticide is a synergistic compound combination of methyl salicylate and empedobacter brevis or afidopyropen. Through the synergistic effect of methyl salicylate and empedobacter brevis or afidopyropen, the control effect on cassava tetranychus cinnabarinus is remarkably improved. The methyl salicylate can simulate an induction mode of feeding of phytophagous pests, activate a defense system of the cassava and induce the cassava to generate persistent systematic resistance; empedobacter brevis or afidopyropen directly acts on the spider mites, and quick-acting killing is achieved. The invention provides an innovative solution for green prevention and control of cassava tetranychus cinnabarinus and has important significance for promoting sustainable development of cassava industry.

Description

Technical Field

[0001] The invention belongs to the technical field of spider mite prevention and control, and particularly relates to a green prevention and control method for cassava spider mites based on immune induction. Background Art

[0002] Cassava is a perennial shrub crop of the Euphorbiaceae family, known for its high yield and starch content. Cassava tubers are rich in starch, with fresh tubers containing 20-40% starch and rising to around 80% after drying. It is often called the "king of starch."

[0003] The cinnabarinus spider mite (Tetranychus cinnabarinus Boisduval), a cosmopolitan mite of the family Tetranychidae, is a common pest on cassava in my country. It primarily inhabits the undersides of cassava leaves and sucks sap. Initially, the leaves exhibit a chlorotic and yellowing state. In severe cases, the leaves dry up and fall off, weakening the plants and even causing their death, severely impacting cassava growth and yield. In Guangxi, the climate conditions of prolonged high temperature, low humidity, and low precipitation are highly susceptible to cinnabarinus infestation, and the mite has become a major constraint on the development of the cassava industry in the region.

[0004] Chemical control remains the most widely used method for controlling Tetranychus cinnabarinus, but long-term use can lead to problems such as pesticide resistance, pesticide residues, and environmental pollution. Biological control offers environmental advantages over chemical control. For example, a spore-based formulation of Metarhizium anisopliae can effectively inhibit the development and reproduction of Tetranychus cinnabarinus, with a high lethality to adult mites and eggs. However, the effectiveness of single-ingredient biological agents is limited. Combining different ingredients and screening for synergistic combinations can improve target control effectiveness, but not all combinations of two ingredients will produce a synergistic effect.

[0005] Jasmonic acid and salicylic acid signaling pathways are currently known to be important signaling pathways for crop defense regulation and play a crucial role in crop insect resistance. Studies have found that exogenous application of methyl jasmonate and methyl salicylate, as signaling molecules, can mimic the induction pattern of herbivorous pest feeding and activate plant defense systems. The study "Study on the Effects of Methyl Jasmonate and Methyl Salicylate on Cassava's Defense Against Two-Spotted Spider Mites" demonstrated that exogenous application of methyl jasmonate or methyl salicylate significantly inhibited the development, reproduction, and population growth of two-spotted spider mites. Feeding on cassava treated with methyl jasmonate or methyl salicylate significantly induced the upregulation of the effector proteins Tu28, Tu48, and Tu90, and increased the activities of antioxidant, detoxifying, and digestive enzymes. Furthermore, exogenous application of methyl jasmonate or methyl salicylate significantly increased the accumulation of insect resistance-related substances, such as total phenolics, flavonoids, lignin, and tannins, in both resistant and susceptible cassava plants. In summary, methyl jasmonate or methyl salicylate can induce systemic resistance in cassava and achieve anti-mite effects.

[0006] Regarding the insecticidal activity of methyl salicylate, CN101849556A discloses a botanical synergistic compound acaricide composed primarily of Chuanxiong oil and wintergreen oil, with adjuvants added. The main component of wintergreen oil is methyl salicylate. Furthermore, CN116250540A discloses a biopesticide for controlling macadamia thrips, formulated by combining methyl salicylate with ivermectin, tembacin, or farnesol. This indicates that methyl salicylate exhibits insecticidal and acaricidal activity.

[0007] Based on the above-mentioned effects of methyl salicylate, research and development of the role of methyl salicylate compound compositions in preventing and controlling cassava spider mites is of great significance to the development of the cassava industry. Summary of the Invention

[0008] The present invention aims to provide a green control method for cassava spider mites based on immune induction, which can improve the control effect of cassava spider mites compared with the use of methyl salicylate alone.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A green control method for cassava spider mites based on immune induction comprises spraying a methyl salicylate compound agent during cassava planting or when a cinnabar mite disease occurs; the active ingredient of the methyl salicylate compound agent is a compound of methyl salicylate and breviscapus or diprofenococcus.

[0011] More specifically, the spore count of the Bacillus brevis is 30 billion spores / gram.

[0012] More specifically, the mass ratio of the methyl salicylate to the Stablebacter brevis is 1:15-30.

[0013] More specifically, the mass ratio of methyl salicylate to diprofen is 1-10:10-1.

[0014] The present invention also provides an active biological pesticide, wherein the active ingredient of the active biological pesticide is prepared by compounding methyl salicylate with breviscapus or amphotericin.

[0015] More specifically, the spore count of the Bacillus brevis is 30 billion spores / gram.

[0016] More specifically, the mass ratio of the methyl salicylate to the Stablebacter brevis is 1:15-30.

[0017] More specifically, the mass ratio of methyl salicylate to diprofen is 1-10:10-1.

[0018] The present invention also provides application of the active biological pesticide in preventing and controlling cassava spider mites.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention sprays a methyl salicylate compound during the cassava planting process or when a cinnabar spider mite disease occurs. The methyl salicylate compound is composed of a compound combination of methyl salicylate and breviscapus or diprofenoic acid. The two compound combinations show a combined synergistic effect on cassava cinnabar spider mites in different mass ratio ranges, based on which the control effect of cassava cinnabar spider mites can be improved. Moreover, methyl salicylate is a plant defense signal molecule. When applied exogenously, it activates the cassava plant defense system to resist the harm of pests by simulating the induction mode of herbivorous pests feeding; while breviscapus (biological pesticide) or diprofenoic acid (chemical pesticide) directly acts on spider mites to achieve rapid killing. The synergistic effect of the two not only ensures the rapid control effect, but also achieves long-term control by inducing the plant's own resistance. It can be seen that the compound agent in the present invention can induce cassava to produce systemic endogenous mite resistance, providing an efficient and sustainable pest control solution for the cassava industry, which is of great significance to the development of the cassava industry.

[0021] (2) The methyl salicylate, breviscapus, or diprofenopipron in the methyl salicylate composite agent or active biopesticide of the present invention are all bioactive ingredients, are environmentally friendly, and can effectively avoid the problems associated with the use of chemical agents. In addition, the methyl salicylate composite agent or active biopesticide of the present invention is a composite combination of two active ingredients, which can delay the development of drug resistance in cassava spider mites and reduce the cost of drug resistance management. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 To show the phenotypic damage of cassava plant leaves after treatment with different pesticides;

[0023] Figure 1 In the figure, A: methyl salicylate + 30 billion spores / g of Bacillus brevis treatment; B: methyl salicylate single-dose treatment; C: diprofenoxam single-dose treatment; D: methyl salicylate + diprofenoxam treatment. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solution of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts are within the scope of protection of the present invention.

[0025] Example 1 Activity test of methyl salicylate compound against cassava spider mite

[0026] 1.1 Test agents

[0027] 98% methyl salicylate technical (CAS: 119-36-8, commercially available), 30 billion spores / g of Bacillus brevis technical (Zhenjiang Runyu Biotechnology Development Co., Ltd.), 92.5% amphotericin B technical (commercially available)

[0028] 1.2 Tested pest mites

[0029] Cinnabarinus spider mites (Tetranychus cinnabarinus Boisduval) were collected from cassava leaves and fed with fresh, clean cassava leaves in the laboratory for five generations. Female adults of uniform size were selected as test mites. Rearing conditions: 25 ± 1°C, 16 L / 8 D photoperiod.

[0030] 1.3 Test methods

[0031] The toxicity of methyl salicylate, breviscapus, and diprofenoic acid alone and their mixtures against Tetranychus cinnabarinus was determined by leaf disk spray method.

[0032] 1.3.1 Leaf disc inoculation

[0033] Select fresh, clean cassava leaves (unexposed to pesticides) of uniform growth and use a hole punch to create 2-cm-diameter leaf discs. Place a damp sponge in a 9-cm-diameter Petri dish, place filter paper on top of the damp sponge, and place two leaf discs on the filter paper. Inoculate the leaf discs with the test mite pest, with 15 mite per disc.

[0034] 1.3.2 Preparation of liquid medicine

[0035] Methyl salicylate technical and amphotericin technical were dissolved in dimethyl sulfoxide and diluted with 0.1% Tween-80 aqueous solution to form a single-dose stock solution. 30 billion spores / g of Bacillus brevis (based on 100% by mass) were diluted with 0.1% Tween-80 aqueous solution to form a single-dose stock solution of a spore suspension. Based on preliminary test results, multiple formulations were set up. Each single-dose stock solution and each formulation mixture were further diluted with 0.1% Tween-80 aqueous solution to form six concentration gradients. These formulations were prepared for immediate use.

[0036] 1.3.3 Spray Observation

[0037] The culture dish was placed in a Potter spray tower (1.47×10 5The mice were sprayed on a 1 mL plate (Pa) under a 100-μm (100-μm) flask. The solution was allowed to settle for 1 minute before removal and transfer to a 25 ± 1°C, 16 L / 8-day photoperiod. Four replicates were set for each concentration, with a 0.1% Tween-80 aqueous solution used as a blank control. After 48 hours, the mice were observed for mortality (using a soft brush to touch the appendages; if no movement occurred, the mite was considered dead). The adjusted mortality rate for each treatment was calculated.

[0038]

[0039] In the above formula: P is the mortality rate, in %; K is the number of dead insects; N is the total number of insects treated.

[0040]

[0041] In the above formula: P1--corrected mortality rate, unit is %; P t --Treatment mortality, unit is %; P0--blank control mortality, unit is %.

[0042] 1.4 Data Analysis

[0043] DPS software was used to perform regression analysis on the logarithmic concentration of each treatment agent and the corrected mortality probability value of each treatment to calculate the LC of each treatment agent. 50 The co-toxicity coefficient (CTC value) of the mixture was calculated using Sun Yunpei method with methyl salicylate as the standard agent.

[0044]

[0045] In the above formula: ATI - the toxicity index of the mixture; S - the LC of the standard agent 50 , the unit is mg / L; M--LC of the mixture 50 , unit is mg / L.

[0046] TTI=TI A ×P A +TI B ×P B

[0047] In the above formula: TTI - theoretical toxicity index of mixture; TI A --Toxicity index of agent A; P A --The percentage of agent A in the mixture, expressed as percentage (%); TI B --Toxicity index of agent B; P B --The percentage of agent B in the mixture, in percentage (%).

[0048]

[0049] In the above formula: CTC - co-toxicity coefficient; ATI - measured toxicity index of mixture; TTI - theoretical toxicity index of mixture.

[0050] 1.5 Efficacy evaluation

[0051] The type of combined synergistic effect of the drugs was evaluated according to the co-toxicity coefficient (CTC): CTC ≤ 80 was antagonistic, 80 < CTC < 120 was additive, and CTC ≥ 120 was synergistic. The results are shown in Table 1-2.

[0052] Table 1 Types of combined effects of methyl salicylate and Bacillus brevis on cassava spider mites

[0053]

[0054] As shown in Table 1, the LC50 values of methyl salicylate and Bacillus brevis against Tetranychus cinnabarinus were 9.6215 mg / L and 76.8452 mg / L, respectively. When the two were combined in a mass ratio of 1:1-40, the cotoxicity coefficients of the combination ranged from 80 to 120 at a mass ratio of 1:40, 1:7, or 1:3, indicating an additive effect. At a mass ratio of 1:1, the cotoxicity coefficient was less than 80, indicating an antagonistic effect. Only at a mass ratio of 1:15-30 did the cotoxicity coefficient exceed 120, indicating a synergistic effect. This suggests that the combined use of methyl salicylate and Bacillus brevis at a mass ratio of 1:15-30 exhibits a synergistic effect against Tetranychus cinnabarinus, potentially improving control effectiveness against the plant.

[0055] Table 2 Types of combined effects of methyl salicylate and dicyclopentadione on cassava spider mites

[0056]

[0057]

[0058] Table 2 shows that the LC50 values for methyl salicylate and abicyclopyrin against Tetranychus cinnabarinus are 9.6215 mg / L and 76.8452 mg / L, respectively. When the two are combined in a mass ratio of 1-10:10-1, the cotoxicity coefficient against Tetranychus cinnabarinus is greater than 120, demonstrating a synergistic effect. This suggests that when methyl salicylate and abicyclopyrin are used in a mass ratio of 1-10:10-1, they exhibit a synergistic effect against Tetranychus cinnabarinus, potentially improving control effectiveness against the plant.

[0059] Example 2 Field Verification

[0060] The efficacy of single agents of methyl salicylate and acyclopyrin, as well as a mixture of methyl salicylate + 30 billion spores / g of Bacillus brevis (mass ratio 1:30) and methyl salicylate + acyclopyrin (mass ratio 1:3) in improving mite resistance in cassava plants was verified. The above agents were prepared into single-dose stock solutions according to the method described in Example 1, and then the mixtures were prepared and diluted to the desired concentrations.

[0061] Cassava plants were sprayed with pesticides 60 days after planting, with 50 plants per treatment. Cassava plants were then inoculated with spider mites to provide a feeding stress treatment. Sixty mites were inoculated on the underside of the 4th, 5th, and 6th fully expanded leaves of each cassava plant, with 20 mites per leaf. To prevent mites from escaping, the cassava petioles were immediately wrapped with glycerin-soaked cotton balls after inoculation. Eight days after inoculation, the extent of spider mite damage on cassava plants was assessed. Results are shown in the table. Figure 1 .

[0062] Depend on Figure 1 As can be seen, cassava leaves sprayed with either methyl salicylate or acyclopyrin developed yellow spots on their surfaces and even curled and wilted. However, cassava leaves treated with either a mixture of methyl salicylate and 30 billion spores / g of Bacillus brevis or acyclopyrin remained dark green and showed no obvious mite damage. This suggests that the combination of methyl salicylate with either 30 billion spores / g of Bacillus brevis or acyclopyrin can enhance the anti-mite effect of cassava plants.

[0063] In summary, when methyl salicylate is combined with breviscapus or diprofenoic acid in the present invention, the two combined combinations exhibit a combined synergistic effect on the control of cassava spider mites at different mass ratios, thereby improving the control effect on cassava spider mites. Moreover, methyl salicylate, as a signal molecule, can be applied exogenously to simulate the induction mode of feeding by herbivorous pests, inducing cassava plants to produce a defense system to resist pest damage and reduce the damage caused by spider mites. Therefore, the composite agent of the present invention can induce systemic endogenous mite resistance in cassava, providing a highly efficient and sustainable pest control solution for the cassava industry, which is of great significance to the development of the cassava industry.

[0064] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A green control method for cassava spider mites based on immune induction, characterized in that: During the cassava planting process or when spider mites cinnabarinus occur, a methyl salicylate compound agent is sprayed; the active ingredients of the methyl salicylate compound agent are a combination of methyl salicylate and breviscapus or diprofenococcus.

2. The green control method for cassava spider mites based on immune induction according to claim 1, characterized in that: The spore count of the Bacillus brevis is 30 billion spores / gram.

3. The green control method of cassava spider mite based on immune induction according to claim 1, characterized in that: The mass ratio of the methyl salicylate to the Stable Bacillus brevis is 1:15-30.

4. The green control method of cassava spider mite based on immune induction according to claim 1, characterized in that: The mass ratio of the methyl salicylate to the diprofen is 1-10:10-1.

5. An active biological pesticide, characterized in that: The active ingredient of the active biological pesticide is prepared by compounding methyl salicylate with breviscapus or diprofenoic acid.

6. The active biological pesticide according to claim 5, characterized in that The spore count of the Bacillus brevis is 30 billion spores / gram.

7. The active biological pesticide according to claim 5, characterized in that The mass ratio of the methyl salicylate to the Stablebacterium brevis is 1:15-30.

8. The active biological pesticide according to claim 5, characterized in that The mass ratio of the methyl salicylate to the diprofen is 1-10:10-1.

9. Use of the active biological pesticide according to any one of claims 5 to 8 in controlling cassava spider mites.

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