A nematicidal composition and uses thereof

Abstract

The application discloses a nematicidal composition and application thereof, wherein the composition contains active ingredient A and active ingredient B, the weight ratio of the active ingredient A to the active ingredient B is 1:50-50:1, the active ingredient A is a compound shown as a formula I, and the active ingredient B is a nematicidal thiazole. The nematicidal composition is used for preventing and treating plant parasitic nematodes, has good nematicidal activity, and has little toxicity to human and animals.

Description

[0001] This invention application is a divisional application of application number 202211422511.3, filed on November 15, 2022, entitled "A nematicide composition and its use". Technical Field

[0002] This invention belongs to the technical field of pesticide nematicide compositions, specifically relating to a nematicide composition and its uses. Background Technology

[0003] There are as many as 200 genera and more than 5,000 species of plant parasitic nematodes. Among them, the major plant parasitic nematodes that harm agricultural and forestry production include root-knot nematodes (Meloidogyne), cyst nematodes (Heterodera), smooth blade nematodes (Aphelenchina), stem nematodes (Ditylenchus), root nodule nematodes (Nacobbus), root rot nematodes (Pratylenchus), and pine wood nematodes (Bursa phelenchus xylophilus).

[0004] Emamectin benzoate, or simply emamectin, is a novel, highly effective semi-synthetic antibiotic insecticide synthesized from the fermentation product emamectin B1. It effectively controls damage to crops from Lepidoptera, Homoptera, Coleoptera, and various nematodes. Emamectin benzoate's mechanism of action involves enhancing the activity of neurotransmitters such as glutamate and gamma-aminobutyric acid (GABA), thereby allowing GABA to enter nerve cells. This results in an agonistic effect on GABA, causing a large release of GABA from nerve endings. Furthermore, it promotes a prolonged and strong binding of GABA to the cell membranes of secondary neurons or effector cells, leading to a large influx of chloride ions into nerve cells, disrupting nerve conduction, and causing cell function loss. Larvae quickly cease feeding after contact with the pesticide, experiencing irreversible paralysis. Simultaneously, because it binds tightly to the soil and does not leach, it does not accumulate in the environment and can be transferred via translaminar movement to penetrate the epidermis of target crops, prolonging its effective period.

[0005] Benclothiazide belongs to the benzothiazide class of nematicides; CAS Registry Number: 89583-90-4, its English chemical name is 7-chloro-1,2-benzisothiazole. Compound I is a novel nematicide developed by Syngenta, which paralyzes nematode larvae and inhibits egg production. Direct application or seed treatment can effectively control root-knot nematodes, beet cysts, and corn short-bodied nematodes on crops such as cucumber, tomato, corn, and sugar beets. Chemical formula: C 17 H 13Cl2F3N2O, with a relative molecular mass of 389.20, has the following chemical structural formula:

[0006]

[0007] Nematode control methods include agricultural control, physical control, chemical control, and biological control. Because chemical pesticides are fast-acting, chemical control remains the primary method for nematode control in actual production. However, long-term use of single or highly toxic chemical nematicides has led to problems such as increased disease resistance, increasing pesticide usage year by year, soil microbial imbalance, and increased pesticide residues in crops.

[0008] Determining the bioactivity of compounds against targets and exploring different combinations is an effective method for developing pesticides, improving control efficacy, and delaying nematode resistance. The inventors of this invention conducted in-depth research on compound I, emamectin benzoate, nematicide, and their combinations. They discovered that compound I, emamectin benzoate, and nematicide exhibit good activity against root-knot nematodes. Furthermore, mixing compound I with any one of emamectin benzoate or nematicide within a certain mixing ratio range shows a significant synergistic effect against nematodes, effectively improving nematode control. Further research led to the completion of this invention. There are currently no reports on the use of compound I mixed with any one of emamectin benzoate or nematicide for the control of plant-parasitic nematodes. Summary of the Invention

[0009] The purpose of this invention is to provide a pesticide composition with high activity against nematodes, thereby improving actual control efficacy and effectively delaying the development of nematode resistance.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a nematicide composition, wherein the composition contains active ingredient A and active ingredient B, and the mass ratio of active ingredient A to active ingredient B is 1:50 to 50:1;

[0011] The active ingredient A is a compound of formula I.

[0012]

[0013] The active ingredient B is either emamectin benzoate or thiamethoxam.

[0014] Furthermore, the weight ratio of active ingredient A to active ingredient B is 1:32 to 45:1;

[0015] Further, the weight ratio of active ingredient A to active ingredient B is 1:50, 1:32, 1:30, 1:16, 1:10, 1:7, 1:6, 5:2, 5:3, 1:1, 6:1, 8:1, 10:1, 15:1, 25:1, or 45:1.

[0016] Furthermore, the mass ratio of the compound of formula I to emamectin benzoate is 1:7 to 15:1;

[0017] Furthermore, the mass ratio of the compound of formula I to emamectin benzoate is 1:7 to 10:1;

[0018] Furthermore, the mass ratio of the compound of formula I to thiamethoxam is 1:30 to 15:1;

[0019] Furthermore, the mass ratio of the compound of formula I to thiamethoxam is 1:10 to 8:1;

[0020] Furthermore, the total weight of active ingredient A and active ingredient B accounts for 0.1%-90% of the composition;

[0021] Furthermore, the total weight of active ingredient A and active ingredient B accounts for 1%-50% of the composition;

[0022] Furthermore, the total weight of active ingredient A and active ingredient B accounts for 1%-20% of the composition;

[0023] Furthermore, the composition contains not only the active ingredient but also agriculturally permitted pesticide adjuvants;

[0024] Furthermore, the pesticide adjuvant component of the composition is selected from one or more of the following: wetting agent, dispersant, emulsifier, thickener, disintegrant, antifreeze, defoamer, solvent, preservative, stabilizer, synergist and carrier;

[0025] Furthermore, the composition can be prepared into agriculturally permissible formulations, including granules, emulsifiable concentrates, and soluble concentrates.

[0026] The application of a nematicidal composition in killing plant parasitic nematodes, wherein the nematodes are any one or more of the following: root-knot nematode (Meloidogyne), cyst nematode (Heterodera), smooth blade nematode (Aphelenchina), stem nematode (Ditylenchus), root nodule nematode (Nacobbus), root rot nematode (Pratylenchus), and pine wood nematode (Bursaphelenchus xylophilus).

[0027] Furthermore, the nematodes mentioned are cyst nematodes and root-knot nematodes;

[0028] Furthermore, the cyst nematode is *Cephalomysoma granatum*; the root-knot nematode is *Meloidogyne incongnita (Kofold & White) Chitwood*.

[0029] Root-knot nematodes (Meloidogyne spp.) are soil-dwelling endoparasitic nematodes belonging to the phylum Nematoda, class Seminaria, order Tylenchida, superfamily Heteroderidea, family Meloidogyne, and genus Meloidogyne Goeldi. They have become one of the most important pathogenic organisms affecting crops. Currently, the most serious pathogenic nematode in greenhouse vegetable production in my country is the southern root-knot nematode [Meloidogyne incongnita (Kofold & White)].

[0030] Chitwood, with its rapid reproduction rate, strong resistance, and easy spread, is currently a major target for control. Root-knot nematode disease is one of the main soil-borne diseases of greenhouse vegetables. Vegetables parasitized by root-knot nematodes will produce a large number of root knots, which will destroy the normal physiological functions of the roots and lead to root rot in severe cases. At the same time, the above-ground parts will show stunted growth, poor development, and reduced yield. The wounds created by root-knot nematodes will facilitate the invasion of other soil pathogens, forming a complex disease. After the second instar invades the plant root system, it will create wounds. At this time, harmful pathogens in the soil will also take the opportunity to enter the plant through the wounds, causing the occurrence and damage of other soil-borne diseases such as bacterial wilt, Fusarium wilt, damping-off, and root rot, causing secondary damage to greenhouse vegetables.

[0031] Cereal cyst nematode (CCN, Heterodera avenae, Wollenweber 1924) is an important infectious pathogenic nematode belonging to the order Tylenchida, suborder Tylenchina, family Heteroderidae, and genus Heterodera. It mainly infects the roots of cereal crops and reproduces rapidly, causing the crop roots to develop into spherical galls, thereby hindering and inhibiting crop growth and affecting crop yield.

[0032] Furthermore, the plants mentioned include: cucumber, tomato, peanut, tobacco, sweet potato, ginger, rice, loofah, bitter melon, watermelon, soybean, banana, pepper, sugarcane, strawberry, potato, citrus, kiwi, wheat, kenaf, and celery. Among these, the high humidity, monoculture soil structure, and continuous cropping practices within the facilities lead to severe root-knot nematode infestations in greenhouse vegetables, including cucumber, tomato, loofah, bitter melon, and celery.

[0033] The present invention has the following advantages over the prior art:

[0034] 1) The composition described above has good nematicidal activity;

[0035] 2) It has low toxicity, leaves little residue in crops, and poses little harm to humans and livestock. It effectively solves the problem of existing nematicides having high toxicity and leaving a lot of residue in crops, thus improving the safety of agricultural production.

[0036] 3) The composition is a mixture of compounds with different mechanisms of action, which can delay the development of drug resistance in nematodes, reduce environmental pressure, and extend the lifespan of the compounds. Detailed Implementation

[0037] To better understand the essence of the present invention, the following detailed description of the present invention is provided in conjunction with embodiments. The contents mentioned in the embodiments are not intended to limit the present invention. The selection of process conditions such as temperature and time in the preparation method can be adapted to local conditions and has no substantial impact on the results.

[0038] Indoor activity

[0039] Example 1

[0040] Nematode collection methods (preparation of nematode suspension)

[0041] Root-knot nematodes: Take several tomato root nodules from the field, pick out the white egg masses under a binocular microscope, place them in a hatching sieve, hatch at 25℃, and prepare a nematode suspension for later use (each 1mL of suspension contains no less than 100 second-instar larvae nematodes).

[0042] Cyst nematodes: Soil samples were taken from wheat fields and brought to the laboratory. The soil samples were mashed and mixed thoroughly. The soil was then rinsed with water while being stirred, sieved (100 mesh), and centrifuged. The cysts in the 100-mesh sieve were placed in a hatching sieve and soaked in sterile water at 4°C for 8 weeks. The cysts were then hatched at 16°C. The second generation of hatched nematodes was used as a starting point. A nematode suspension was prepared for use (each 1 mL of suspension contained no less than 100 second-instar larvae).

[0043] Experimental treatment and methods: Compound I, emamectin benzoate, and thiamethoxam technical grade were dissolved in acetone to prepare high-concentration stock solutions. These stock solutions were then diluted proportionally with a 0.1% Tween 80 aqueous solution containing an appropriate amount of surfactant to create a series of concentrations. Preliminary experiments were conducted on Compound I with emamectin benzoate, thiamethoxam, and their different ratios of mixtures. Based on these results, the experimental concentration range for each mixture was determined. Five concentration treatments were set for each agent according to the content of the active ingredient, with an aqueous solution containing the same amount of the agent serving as a control.

[0044] Assay method: The immersion method was used. Using a pipette, 3 mL of the drug solution was added to each test tube in turn, from low concentration to high concentration. Then, 3 mL of the prepared nematode suspension was added to the test tube to mix the drug solution and nematode suspension evenly. 3 mL of the mixture was then transferred to the well of a multi-well biochemical test plate and capped. Each treatment was repeated 4 times, and a treatment without the drug was set as a control.

[0045] Investigation method: The nematodes were placed in a constant temperature and light incubator at 16℃. After 24 hours, the mortality of the second instar larvae of root-knot nematodes was checked (the nematodes were considered dead when they could not bend or move when touched with a bamboo needle). 1 mL of the mixture from each treatment was taken and the mortality of the nematodes was observed under a dissecting microscope. The number of root-knot nematodes and the number of dead nematodes were recorded, and the corrected mortality rate was calculated.

[0046] Statistical Analysis: Based on the logarithmic concentrations of each drug and their corresponding mortality rates, regression analysis was performed using IBM SPSS Statistics 20 software to determine the b-value of the regression equation for each drug (y = a + bx), and the LC was calculated. 50 and 95% confidence limit and R 2 .

[0047] The experimental results were calculated using IBM SPSS Statistics 20 data processing software. The toxicity regression equation b-value and LC-value were obtained for two single-agent drugs and five combinations of the test drugs. 50 and 95% confidence limit and R 2 .

[0048] The co-toxicity coefficient (CTC) of the mixture was calculated using Sun Yunpei's method to evaluate the type of combined effect. A CTC ≥ 120 indicates a synergistic effect, a CTC ≤ 80 indicates an antagonistic effect, and a CTC between 80 and 120 indicates an additive effect.

[0049] Table 1. Indoor bioassay results of Formula I compounds, emamectin benzoate, and their mixtures on southern root-knot nematodes.

[0050]

[0051] The mechanisms of action of Compound I and emamectin benzoate differ, and their combined use helps overcome or delay the development of nematode resistance, reduces dosage, lowers costs, and improves efficacy. Experimental results (see Table 1) show that the mixture of Compound I and emamectin benzoate in a ratio ranging from 1:32 to 45:1 exhibits good control effects against southern root-knot nematodes, demonstrating a synergistic effect.

[0052] When the ratio of compound I to emamectin benzoate is 1:7-10:1, the CTC > 145, indicating a significant synergistic effect. When the ratio of compound I to emamectin benzoate is 1:1, the CTC value is the highest at 170.937, and the activity is the best at this ratio.

[0053] Table 2 shows the in vitro assay results of compound I, emamectin benzoate, and their mixtures on *Nematodea gramineus*.

[0054]

[0055] The experimental results (see Table 2) show that the mixture of compound I and emamectin benzoate in the range of 1:10-15:1 has a good control effect on gramineous cyst nematodes. The combined effect is synergistic. Among them, the CTC value is the largest (171.023) when the mixture ratio of compound I and emamectin benzoate is 5:3, and the activity is the best at this ratio.

[0056] Table 3 shows the in vitro assay results of compound I, nematichizazole and its mixtures on *Nematodea gracilis*.

[0057]

[0058] The experimental results (see Table 3) show that the mixture of compound I and nematicides in the range of 1:50-25:1 has a good control effect on gramineous cyst nematodes. The combined effect is synergistic. Among them, the CTC value is the largest (171.589) when compound I is mixed with emamectin benzoate in a ratio of 1:10, and the activity is the best at this ratio.

[0059] Formulation Examples:

[0060] Granule processing technology: The active ingredient, dispersant and adjuvant are mixed evenly to form a master powder. The master powder and carrier are added together to the coating granulator and stirred. While stirring, the prepared binder aqueous solution is added. After being fully mixed, the mixture is discharged, dried and sieved to obtain the granules of the present invention.

[0061] Example 2

[0062] 4.0% Formula I compound emamectin benzoate granules (1:1)

[0063] Formula: 2.0% Formula I compound, 2.0% emamectin benzoate, 2.5% polyvinyl acetate, 3.0% sodium lignosulfonate, 2.5% silica, supplemented by attapulgite granular carrier.

[0064] Example 3

[0065] 14.0% Formula I compound nematicide granules (1:6)

[0066] Formula: 2.0% Formula I compound, 12.0% thiamethoxam, 0.8% polyvinylpyrrolidone, 3.5% sodium lignosulfonate, 8.0% silica, and bentonite granular carrier to make up the difference.

[0067] Emulsifiable concentrate processing technology: The active ingredient is dissolved in a solvent in a certain proportion, and then a certain amount of emulsifier and other additives are added. The homogeneous transparent oily liquid prepared by stirring and mixing is the emulsifiable concentrate of the present invention.

[0068] Example 4

[0069] 16.0% Formula I compound emamectin benzoate emulsifiable concentrate (5:3)

[0070] Formula: 10.0% Formula I compound, 6.0% emamectin benzoate, 12.0% tristyrene-phenylphenol polyoxyethylene ether, 3.0% calcium dodecylbenzenesulfonate, 20.0% cyclohexanone, 20% DMF, xylene to make up the balance.

[0071] Example 5

[0072] 11.0% Formula I compound nematicide emulsifiable concentrate (1:10)

[0073] Formula: 1.0% Formula I compound, 10.0% thiamethoxam, 12.0% alkylaryl polyoxyethylene polyoxypropylene ether, 3.0% calcium dodecylbenzenesulfonate, 15.0% cyclohexanone, 20.0% N-methylpyrrolidone, and 200# solvent oil to make up the balance.

[0074] Soluble solution processing technology: The active ingredient is dissolved in a solvent in a certain proportion, and then a certain amount of emulsifier and other additives are added. The homogeneous transparent oily liquid prepared by stirring is the soluble solution of the present invention.

[0075] Example 6

[0076] 8.0% Formula I compound emamectin benzoate soluble concentrate (5:3)

[0077] Formula: 5.0% Formula I compound, 3.0% emamectin benzoate, 4.0% fatty alcohol polyoxyethylene ether, 12.0% tristyrylphenol polyoxyethylene ether, 10.0% dimethyl sulfoxide, 20.0% cyclohexanone, DMF to make up the balance.

[0078] Example 7

[0079] 8.0% Formula I compound · nematichiazole soluble concentrate (1:7)

[0080] Formulation: 1.0% Formula I compound, 7.0% methylthiazole, 4.0% fatty alcohol polyoxyethylene ether, 12.0% tristyrene-phenol polyoxyethylene ether, 10.0% propylene carbonate, 20.0% cyclohexanone, DMF to make up the balance.

[0081] Field efficacy trials

[0082] Example 8: Field efficacy trial of different mixed pairs against root-knot nematodes

[0083] Experimental subjects, crops, and varieties: Tomato root-knot nematode (Meloidogyne spp.), which was isolated and identified primarily as southern root-knot nematode [Meloidogyne incongnita (Kofold & White) Chitwood].

[0084] Experimental materials: The tomato variety was Tianzheng 1567, which was growing well.

[0085] The experiment was conducted in a tomato and vegetable greenhouse in Yangtun Village, Xinxiang City, Henan Province.

[0086] Area and overlap of each cell: 20m² 2 Repeat 4 times.

[0087] Table 4 Experimental Design of Test Reagents

[0088]

[0089]

[0090] The experiment was conducted on April 18, 2019, using root drenching / broadcasting methods for pesticide application.

[0091] Investigation method: A five-point sampling method was used, with 4 plants investigated at each point, and the incidence rate, disease index and control effect were calculated.

[0092] Methods for grading diseased plants:

[0093] Grade 0: No insect galls on the roots;

[0094] Grade 1: The root system has a small number of small insect galls;

[0095] Level 3: Two-thirds of the root system is covered with small galls;

[0096] Level 5: The root system is covered with small galls and secondary galls;

[0097] Level 7: The root system forms a cluster of fibrous roots.

[0098] Disease index = [∑(number of diseased plants at each level × relative level value) / (total number of plants surveyed × 7)] × 100;

[0099] Prevention and control efficacy (%) = [(CK-PT) / CK] × 100;

[0100] In the formula, CK is the disease index of the blank control area; PT is the disease index of the drug-treated area.

[0101] Table 5. Results of field trials

[0102]

[0103] Note: The efficacy (%) of each of the above examples is the average of all replicates.

[0104] As shown in Table 5, all embodiments of the control of tomato root-knot nematodes have good effects. 30 days after application, the control efficacy against nematodes in all embodiments is above 90%.

[0105] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. The use of a nematicidal composition for controlling cereal cyst nematodes, characterized in that, The composition contains active ingredient A and active ingredient B, wherein active ingredient A is a compound of formula I. I, wherein the active ingredient B is nematicide; the mass ratio of the compound of formula I to nematicide is 1:30~15:

1.

2. The use according to claim 1, characterized in that, The mass ratio of the compound of formula I to thiamethoxam is 1:10 to 8:

1.

3. The use according to claim 1, characterized in that, The total weight of active ingredient A and active ingredient B accounts for 1%-50% of the composition.

4. The use according to claim 3, characterized in that, The total weight of active ingredient A and active ingredient B accounts for 1%-20% of the composition.

5. The use according to claim 1, characterized in that, In addition to the active ingredient, the composition also includes agriculturally permitted pesticide adjuvants.

6. The use according to claim 5, characterized in that, The pesticide adjuvant is selected from one or more of the following: wetting agents, dispersants, emulsifiers, thickeners, disintegrants, antifreeze agents, defoamers, solvents, preservatives, stabilizers, synergists, and carriers.

7. The use according to claim 1, characterized in that, The composition is prepared into an agriculturally permissible formulation, wherein the formulation is granules, emulsifiable concentrate, or soluble concentrate.

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