Biopesticide for preventing and treating citrus red mites

Abstract

The invention belongs to the technical field of pesticides, and particularly relates to a biopesticide for preventing and treating citrus red mites, the active component of the biopesticide is formed by compounding beauveria bassiana and cyflumetofen, or is formed by compounding beauveria bassiana and guadipyr; the number of spores in the beauveria bassiana is 5 billion spores per gram. The compounded combination of the biopesticide has a synergistic effect on the citrus red mites within a certain mass ratio range, especially when the compounding mass ratio of the beauveria bassiana to the guadipyr is 1: 30 and 1: 20, the co-toxicity coefficient reaches 418.133 and 317.078, the synergistic effect is remarkable, and the prevention and treatment effect on the citrus red mites can be improved. Besides, the biopesticide is prepared by compounding two insecticidal active components, and the insecticidal action mechanisms are different, so that the risk of drug resistance is reduced, and an effective direction can be provided for comprehensive treatment of drug-resistant pests. Secondly, the biopesticide provided by the invention is beneficial to reducing the dosage and frequency of the pesticide, so that the cost of preventing and treating the citrus red mites is reduced, and the environmental pressure is relieved.

Description

Technical Field

[0001] This invention belongs to the field of pesticide technology, specifically relating to a biological pesticide for controlling citrus red spider mites. Background Technology

[0002] Citrus red spider mite, also known as citrus red spider mite ( Panonychus citir The citrus red spider mite (C. citrus) belongs to the order Acari and family Tetranychidae. It is a major pest of citrus, with nymphs and adults feeding on sap from leaves, young shoots, and fruits. Affected leaves show white mottled spots, chlorosis, and a dull peel. Affected fruits show pale green spots on young fruits and pale yellow spots on mature fruits. Outbreaks of citrus red spider mites can cause leaf and fruit drop, severely impacting citrus quality and yield.

[0003] Currently, the control of citrus red spider mites mainly relies on chemical pesticides. However, with the continuous increase in the dosage and frequency of chemical pesticide application, the problem of pesticide resistance is gradually becoming prominent. Existing technologies have been disclosed, showing that citrus red spider mites have developed high levels of resistance to pesticides such as etoxazole, etoxazole, bifenazate, and abamectin, and moderate levels of resistance to pesticides such as cypermethrin, pyridaben, and spirodiclofen. Therefore, it is urgent to find ways to reduce the dosage and frequency of chemical pesticide application to delay the development of resistance in citrus red spider mites.

[0004] Combining different pesticide active ingredients is one of the effective and convenient methods for developing new pesticide products and controlling resistant pests and diseases. Among these, synergistic combinations can significantly improve control efficacy, help reduce dosage and frequency of application, and delay the development of pest resistance, making it a crucial approach to integrated pest management. However, not all combinations produce synergistic effects; extensive testing is usually required to determine the specific effects of pesticide combinations.

[0005] The inventors screened out a combination of Beauveria bassiana with fenflurfen or imidacloprid through indoor biological testing, which showed a synergistic effect against citrus red spider mites within a certain mass ratio range. Currently, no similar combination has been reported domestically or internationally. Summary of the Invention

[0006] The purpose of this invention is to provide a biological pesticide for controlling citrus red spider mites, so as to solve the problems existing in the control of citrus red spider mites by existing chemical agents.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A biological pesticide for controlling citrus red spider mites, wherein the active ingredient of the biological pesticide is a compound of Beauveria bassiana and diflubenzuron, or a compound of Beauveria bassiana and pendimethalin; wherein the number of spores in Beauveria bassiana is 50 billion spores / gram.

[0008] Furthermore, the mass ratio of the compound Beauveria bassiana to dicofol is 1:35-15.

[0009] Furthermore, the mass ratio of the compound Beauveria bassiana to pendimethalin is 1:40-10.

[0010] Furthermore, the mass ratio of the compound Beauveria bassiana to pendimethalin is 1:30 or 1:20.

[0011] The present invention also provides a biological pesticide formulation, wherein the biological pesticide formulation comprises the active ingredient of the biological pesticide.

[0012] Furthermore, the active ingredient of the biopesticide accounts for 0.05-5% of the total mass of the biopesticide formulation, with the remainder being auxiliary ingredients permitted to be added in pesticide science.

[0013] Compared with the prior art, the present invention has the following beneficial effects: (1) The compound combination of biological pesticides of the present invention has a synergistic effect on citrus red spider mites within a certain mass ratio range. In particular, when the mass ratio of Beauveria bassiana and pendimethalin is 1:30 and 1:20, the co-toxicity coefficients reach 418.133 and 317.078, respectively, and the synergistic effect is more significant, which can improve the control effect on citrus red spider mites.

[0014] (2) The biological pesticide of the present invention is composed of two insecticidal active ingredients with different insecticidal mechanisms, which helps to reduce the risk of drug resistance and can provide an effective direction for the integrated management of drug-resistant pests.

[0015] (3) The biological pesticide of the present invention helps to reduce the dosage and frequency of pesticide application, thereby reducing the cost of controlling citrus red spider mites and alleviating environmental pressure. Detailed Implementation

[0016] It should be noted that, based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0017] Indoor life test 1. Test reagents 50 billion spores / gram of Beauveria bassiana technical (Shanxi Kegu Biopesticide Co., Ltd.), 98% diflubenzuron technical (Henan Lvkang Biotechnology Co., Ltd.), 98% pendimethalin technical (Shanghai Saikerui Biotechnology Co., Ltd.) A spore suspension of 50 billion spores / gram of Beauveria bassiana technical material (based on 100% mass) was prepared using a 0.1% Tween-80 aqueous solution, which serves as the single-agent stock solution. Fenflufenicol and imidacloprid were dissolved in a solvent and then diluted with a 0.1% Tween-80 aqueous solution to prepare high-concentration single-agent stock solutions. Multiple formulations were then prepared, and each single-agent stock solution and each formulation mixture was further diluted with a 0.1% Tween-80 aqueous solution to create five different mass concentration gradients for later use. All the above preparations should be used immediately.

[0018] 2. Test mites Citrus red spider mites were collected from citrus orchards and reared for eight generations in the laboratory using fresh, clean, pesticide-free citrus young leaves and shoots. Healthy nymphs of appropriate age were selected as experimental subjects. Rearing conditions: 25±1℃, relative humidity 70±5%, photoperiod 12h light / 12h dark.

[0019] 3. Test Methods The toxicity of single-agent and mixed pesticides against citrus red spider mites was determined using the leaf-dish spray method. Fresh, clean, uniformly grown citrus leaves were selected, and leaf discs with a diameter of 3 cm were prepared. A damp sponge of the same diameter was placed in a 9 cm diameter petri dish, and filter paper and leaf discs were placed on top of the sponge, with 3 leaf discs per dish. The tested mites were inoculated onto the leaf discs, 15 mites per disc. The petri dishes were then transferred to a Potter spray tower and sprayed at 50 PSI with a spray volume of 1 mL. After settling for 1 minute, the dishes were removed, and the openings were sealed with 100-mesh gauze to prevent escape before being returned to their original conditions for observation. Each treatment was replicated in triplicate, and a treatment using a 0.1% Tween-80 aqueous solution served as a blank control.

[0020] After 48 hours, the mortality of the test mites was investigated, and the corrected mortality rate for each treatment was calculated. Mite mortality was defined as the mite's legs remaining motionless when gently touched with a brush.

[0021]

[0022] In the above formula: P -- Mortality rate, in percentages. K --The number of dead insects; N --Total number of insects treated.

[0023]

[0024] In the above formula: P 1 -- Corrected mortality rate, in % P t --Case-level mortality rate, in % P 0 -- Mortality rate in the blank control group, in percent.

[0025] 4. Data Analysis Regression analysis was performed on the logarithmic values ​​of the drug concentrations and the corrected mortality odds values ​​for each treatment to calculate the LC-1 of each treatment. 50 The experimentally determined toxicological index (ATI), theoretical toxicity index (TTI), and co-toxicity coefficient (CTC) were calculated using the Sun Yunpei method. The type of drug action was evaluated based on the calculated CTC value: CTC ≤ 80 indicated antagonistic effect, 80 < CTC < 120 indicated additive effect, and CTC ≥ 120 indicated synergistic effect. The results are shown in Tables 1-3.

[0026] Table 1. Results of in vitro biomass testing of single-dose formulations Drug Name Regression equation Correlation coefficient r <![CDATA[LC 50 (mg / L)]]> Beauveria bassiana y = 0.412x + 4.253 0.962 64.972 Butyric acid y = 4.539x + 4.478 0.991 1.303 Pyrimethanil y = 4.622x + 3.097 0.984 2.581 Table 1 shows the LC50 toxicity of Beauveria bassiana, dicofol, and pendimethalin against citrus red spider mites. 50 The concentrations were 64.972 mg / L, 1.303 mg / L, and 2.581 mg / L, respectively.

[0027] Table 2. Indoor biocompatibility test results of the compound of Beauveria bassiana and fenflurfen. Drug Name and Proportion <![CDATA[LC 50 (mg / L)]]> ATI TTI CTC Beauveria bassiana 64.972 100.000 -- -- Butyric acid 1.303 4986.339 -- -- Beauveria bassiana 1: 35% fenfluroxyfen 0.962 6753.846 4850.608 139.237 Beauveria bassiana 1: 30g diflubenzuron 0.723 8986.445 4828.715 186.104 Beauveria bassiana 1: 25% fenfluroxyfen 0.862 7537.355 4798.403 157.080 Beauveria bassiana 1: 20% dicofol 1.054 6164.326 4753.656 129.675 Beauveria bassiana 1: 15% dicofol 1.133 5734.510 4680.943 122.508 Beauveria bassiana 1: 10g diflubenzuron 1.258 5164.706 4542.127 113.707 Beauveria bassiana 1: 5 fenfluroxyfen 1.437 4521.364 4171.949 108.375 Table 1 shows that when *Beauveria bassiana* and dicofol are combined at a mass ratio of 1:10 or 1:5, the co-toxicity coefficients of the combination are 113.707 and 108.375, respectively, falling between 80 and 120, indicating an additive effect. When *Beauveria bassiana* and dicofol are combined at a mass ratio of 1:35-15, the co-toxicity coefficients are 122.508-186.104, greater than 120, indicating a synergistic effect. This indicates that the combination of *Beauveria bassiana* and dicofol in this invention has a synergistic effect on the biological activity of citrus red spider mites, and can improve the control effect against citrus red spider mites.

[0028] Table 3. Indoor bioassay results of the combination of Beauveria bassiana and pendimethalin. Drug Name and Proportion <![CDATA[LC 50 (mg / L)]]> ATI TTI CTC Beauveria bassiana 64.972 100.000 -- -- Pyrimethanil 2.581 2517.319 -- -- Beauveria bassiana 1: Pendimethalin 40 2.126 3056.068 2458.360 124.313 Beauveria bassiana 1: Pendimethalin 35 1.384 4694.509 2450.171 191.599 Beauveria bassiana 1: Pendimethalin 30 0.637 10199.686 2439.341 418.133 Beauveria bassiana 1: Pendimethalin 25 1.849 3513.899 2424.345 144.942 Beauveria bassiana 1: Pendimethalin 20 0.853 7616.882 2402.208 317.078 Beauveria bassiana 1: Pendimethalin 15 1.596 4070.927 2366.236 172.042 Beauveria bassiana 1: Pendimethalin 10 2.333 2784.912 2297.563 121.212 Table 2 shows that when *Beauveria bassiana* and pendimethalin are combined at a mass ratio of 1:40-10, the co-toxicity coefficient of the combination ranges from 121.212 to 418.133, which is greater than 120, indicating a synergistic effect. In particular, when the mass ratios are 1:30 and 1:20, the co-toxicity coefficients reach 418.133 and 317.078 respectively, demonstrating a significant synergistic effect. This indicates that the combination of *Beauveria bassiana* and pendimethalin of this invention exhibits a synergistic effect on the biological activity of citrus red spider mites, thus improving the control efficacy against citrus red spider mites.

[0029] In summary, the compound combination of the biopesticide of this invention exhibits a synergistic effect against citrus red spider mites within a certain mass ratio range. In particular, when the mass ratios of *Beauveria bassiana* and pendimethalin are 1:30 and 1:20, the co-toxicity coefficients reach 418.133 and 317.078, respectively, demonstrating a significant synergistic effect and improving the control efficacy against citrus red spider mites. Furthermore, the biopesticide of this invention is composed of two insecticidal active ingredients with different insecticidal mechanisms, which helps reduce the risk of pesticide resistance and provides an effective direction for the integrated management of pesticide-resistant pests. Secondly, the biopesticide of this invention helps reduce the dosage and frequency of pesticide application, thereby reducing the cost of controlling citrus red spider mites and alleviating environmental pressure.

Claims

1. A biological pesticide for controlling citrus red spider mites, characterized in that, The active ingredient of the biopesticide is a compound of Beauveria bassiana and diflubenzuron, or a compound of Beauveria bassiana and pendimethalin; the number of spores in Beauveria bassiana is 50 billion spores / gram.

2. The biological pesticide according to claim 1, characterized in that, The mass ratio of Beauveria bassiana to dicofol is 1:35-15.

3. The biological pesticide according to claim 1, characterized in that, The mass ratio of the compound Beauveria bassiana to pendimethalin is 1:40-10.

4. The biological pesticide according to claim 1, characterized in that, The mass ratio of Beauveria bassiana to pendimethalin is 1:30 or 1:

20.

5. A biological pesticide formulation, characterized in that, The biological pesticide formulation includes the active ingredient of the biological pesticide as described in claim 1.

6. The biological pesticide formulation according to claim 5, characterized in that, The active ingredient of the biopesticide accounts for 0.05-5% of the total mass of the biopesticide formulation, with the remainder being auxiliary ingredients permitted to be added in pesticide science.