Root-knot nematode control agent

Abstract

The present invention provides a pest control agent that is readily available and can control root-knot nematodes without adversely affecting crops or workers, as well as a method for controlling root-knot nematodes using the same. [Solution] A root-knot nematode control agent is provided which contains at least one basic amino acid selected from the group consisting of histidine, ornithine, arginine, and lysine, or at least one antioxidant component selected from the group consisting of cysteine, ascorbic acid, glucosamine, and hydroxyphenylacetic acid.

Description

Technical Field

[0001] The present invention relates to a control agent for controlling root-knot nematodes parasitic on the roots of agricultural crops.

Background Art

[0002] Nematodes are a general term for animals belonging to the phylum Nematoda, and there are extremely many species in existence. Most of these nematodes are harmless to humans, but there are known nematodes that parasitize and damage plants. For example, root-knot nematodes, cyst nematodes, and lesion nematodes can be mentioned. Among these, root-knot nematodes represented by Meloidogyne hapla and Meloidogyne incognita parasitize the roots of agricultural crops such as potatoes, carrots, and strawberries, cause the roots to rot, and promote the occurrence of soil diseases such as bacterial wilt. It is said that about 5% of the pest damage to agricultural products worldwide is caused by these root-knot nematodes. To cope with the damage caused by such root-knot nematodes, highly toxic control agents mainly composed of fumigants (methyl bromide) and organophosphorus compounds, which are prohibited from use in Japan, Europe, and the United States, are used.

[0003] However, the spraying of such chemical substances is not preferable from the viewpoint of the safety of crops and workers. In particular, when nematode infection is observed during the growth of agricultural crops, such highly toxic chemical substances cannot be used on the agricultural crops. Therefore, a method for controlling root-knot nematodes while maintaining the safety of agricultural crops and workers is desired.

[0004] Patent Document 1 discloses the use of alkylbenzenes having specific substituents for controlling nematodes such as root-knot nematodes. However, the effects of such compounds on agricultural crops are unclear and are not described in this document either.

[0005] One of the co-applicants of the present application has disclosed a root-knot nematode control agent containing an extract of Bidens pilosa and wood vinegar as active ingredients (Patent Document 2), and a root-knot nematode control agent containing specific organic acids and dicarboxylic acids as active ingredients (Patent Document 3).

[0006] The other co-applicant of this application has discovered that secretions from the fruiting bodies of cellular slime molds belonging to the genus Dictyostelium repel root-knot nematodes, and has succeeded in producing a repellent from these secretions (Patent Document 4). Cellular slime molds are eukaryotic microorganisms that are ubiquitous in soil and usually proliferate in a single-celled state by feeding on bacteria.

[0007] The co-applicants of this application have disclosed a formulation for controlling root-knot nematodes containing ethyl α-D-glucoside (Patent Document 5). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 7-25707 [Patent Document 2] Japanese Patent Publication No. 2013-184890 [Patent Document 3] Japanese Patent Publication No. 2017-1988 [Patent Document 4] Patent No. 6172545 [Patent Document 5] Patent No. 6821158 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] As described above, some conventional root-knot nematode control agents and repellents are harmful as pesticides, and those derived from specific plant varieties or organisms such as slime molds require complex manufacturing processes such as extraction, or require the preparation of large quantities of the organism. Therefore, the object of the present invention is to provide a novel root-knot nematode control agent that can be easily prepared or obtained, and that has high control activity in small quantities. [Means for solving the problem]

[0010] According to a first aspect of the present invention, a root-knot nematode control agent is provided which contains at least one basic amino acid selected from the group consisting of histidine, ornithine, arginine, and lysine. Histidine may also be an oligomer of histidine.

[0011] According to a second aspect of the present invention, a root-knot nematode control agent is provided that contains at least one antioxidant component selected from the group consisting of cysteine, ascorbic acid, glucosamine, and hydroxyphenylacetic acid.

[0012] The root-knot nematode control agent of the present invention further comprises an inorganic or organic carrier, and the basic amino acid or the antioxidant component may be supported on the inorganic or organic carrier. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 shows the arrangement of the samples containing the control components and the sweet potato root-knot nematodes in the petri dishes used in Examples 1 and 2. [Figure 2] Figure 2(a) is a composite micrograph showing the behavior of sweet potato root-knot nematodes in the absence of a histidine-containing sample (Control), and Figure 2(b) is a composite micrograph showing the behavior of sweet potato root-knot nematodes in the presence of a histidine-containing sample. [Figure 3] This graph quantitatively shows the presence of sweet potato root-knot nematodes in histidine-containing samples in regions 1 and 2 in Example 1, compared to the Control. [Figure 4] In Example 2, this graph quantitatively shows the presence of sweet potato root-knot nematodes in samples containing ornithine in regions 1 and 2, compared to the Control. [Figure 5] In Example 3, this graph quantitatively shows the presence of sweet potato root-knot nematodes in samples containing arginine in regions 1 and 2, compared to the control. [Figure 6] In Example 4, this graph quantitatively shows the presence of sweet potato root-knot nematodes in samples containing lysine in regions 1 and 2, compared to the Control. [Figure 7] In Example 5, this graph quantitatively shows the presence of sweet potato root-knot nematodes in cysteine-containing samples in regions 1 and 2, compared to the Control. [Figure 8] In Example 6, this graph quantitatively shows the presence of sweet potato root-knot nematodes in samples containing ascorbic acid in regions 1 and 2, compared to the Control. [Figure 9] In Example 7, this graph quantitatively shows the presence of sweet potato root-knot nematodes in glucosamine-containing samples in regions 1 and 2, compared to the control. [Figure 10] In Example 8, this graph quantitatively shows the presence of sweet potato root-knot nematodes in samples containing 4-hydroxyphenylacetic acid in regions 1 and 2, compared to the Control. [Figure 11] This graph quantitatively shows the presence of sweet potato root-knot nematodes in samples containing secretions (culture supernatant: CM) from cellular slime molds in regions 1 and 2, compared to the control in Example 1. [Figure 12] This is a conceptual diagram showing the arrangement of Lotus corniculatus samples No. 2 and No. 3 on a plate, with the filter paper piece containing the control component in close proximity to sample No. 1, and the sweet potato root-knot nematodes placed below each of the Lotus corniculatus samples. [Figure 13] Graph showing the infection rate of sweet potato root nematodes in Mirabilis jalapa roots for Samples No. 1 - 3 when using filter paper pieces containing only 40% methanol, filter paper pieces containing a control component (histidine), and filter paper pieces containing the secretion of cellular slime mold. [Figure 14] Graph showing the infection rate of sweet potato root nematodes in Mirabilis jalapa roots for Samples No. 1 - 3 when using filter paper pieces containing only 40% methanol, filter paper pieces containing control components (cysteine, ornithine, lysine), and filter paper pieces containing the secretion of cellular slime mold. [Figure 15] Graph showing the infection rate of sweet potato root nematodes in Mirabilis jalapa roots for Samples No. 1 - 3 when using filter paper pieces containing only 40% methanol, filter paper pieces containing control components (ascorbic acid, arginine), and filter paper pieces containing the secretion of cellular slime mold. [Figure 16] Graph showing the infection rate of sweet potato root nematodes in Mirabilis jalapa roots for Samples No. 1 - 3 when using filter paper pieces containing only 40% methanol, filter paper pieces containing a control component (4 - hydroxyphenylacetic acid), and filter paper pieces containing the secretion of cellular slime mold. [Figure 17] Graph showing the infection rate of sweet potato root nematodes in Mirabilis jalapa roots for Samples No. 1 - 3 when using filter paper pieces containing only 40% methanol, filter paper pieces containing a control component (glucosamine), and filter paper pieces containing the secretion of cellular slime mold. [Figure 18] Graph quantitatively representing the presence of sweet potato root nematodes for samples containing histidine oligomers in regions 1 and 2 in comparison with Control. [Figure 19] In Example 9, graph quantitatively representing the presence of sweet potato root nematodes for samples containing potato peptone in regions 1 and 2 in comparison with Control and CM. [Figure 20]In Example 10, this graph quantitatively shows the presence of sweet potato root-knot nematodes in samples containing peptones other than potato peptone or yeast extract in regions 1 and 2, compared to Control, CM, and potato peptone. [Figure 21] This graph quantitatively shows the presence of sweet potato root-knot nematodes in samples containing proteospeptone, tryptone, and BD yeast extract in regions 1 and 2, compared to the Control and CM in Example 10. [Figure 22] This graph shows the infection rates by sweet potato root-knot nematodes in the roots of Lotus corniculatus (samples No. 1-3) when using filter paper soaked only in sterile water, filter paper soaked in the secretions of cellular slime mold, and filter paper soaked in potato peptone. [Modes for carrying out the invention]

[0014] The following describes embodiments of the root-knot nematode control agent of the present invention.

[0015] According to the inventors, it has been found that a control agent containing specific control components can effectively repel root-knot nematodes. These specific control components can be divided into two types: specific basic amino acids and specific antioxidant components.

[0016] The basic amino acids are histidine, ornithine, arginine, or lysine, or any mixture thereof. The antioxidants are cysteine, ascorbic acid, glucosamine, or hydroxyphenylacetic acid, or any mixture thereof. The above basic amino acids or antioxidants can effectively repel root-knot nematodes without wilting crops, killing organisms, or adversely affecting workers. Of the above basic amino acids, histidine is preferred in terms of availability. Of the above antioxidants, cysteine ​​and ascorbic acid are preferred in terms of availability.

[0017] The basic amino acids may be histidine, ornithine, arginine, or lysine, used individually. The mixture of basic amino acids may include all of histidine, ornithine, arginine, and lysine, or any three or two of them. For example, it may include histidine, arginine, and lysine. In addition, other components may be included as long as at least one of the above basic amino acids is included. Histidine, ornithine, arginine, or lysine exist in L-form and D-form, but it has been shown from the examples described later that the L-form is effective.

[0018] The antioxidant component may be cysteine, ascorbic acid, glucosamine, or hydroxyphenylacetic acid, used individually. The antioxidant component may include all of the above, or any three or two of them. In addition, other components may be included as long as at least one of the above antioxidant components is included. Cysteine, ascorbic acid, and glucosamine exist in L-form and D-form, but it has been shown from the examples described later that the L-form of cysteine ​​and ascorbic acid, and the D-form of glucosamine are at least effective.

[0019] Peptone is a general term for a mixture of amino acids and low molecular weight peptides obtained by hydrolyzing proteins. However, various types of peptone exist depending on the raw materials and manufacturing processes. For example, casein peptone, meat peptone, gelatin peptone, potato peptone, wheat peptone, rice peptone, and soy peptone are available. For example, potato peptone contains histidine, arginine, lysine, and cysteine, and can therefore be used as a pest control component containing the above basic amino acids and / or antioxidant components. As for other peptones, any peptone containing the above basic amino acids and / or antioxidant components can be used. Examples of such peptones include bactopeptone (manufactured by Becton Dickinson (BD)), soy peptone (manufactured by Solabia Biokar Diagnostics), Kyokuto peptone (manufactured by Kyokuto Pharmaceutical Industry Co., Ltd.), and proteose peptone (manufactured by BD). Proteose peptone (manufactured by BD) is known to contain at least histidine, arginine, lysine, and cysteine. Of these, potato peptone is preferred because, as shown in the examples below, it exhibits superior pest control effects.

[0020] In addition to peptone, extracts such as yeast extract (manufactured by Kyokuto Pharmaceutical Co., Ltd. or BD Co., Ltd., etc.) and tryptone (manufactured by Hanai Co., Ltd., etc.) can be used. Yeast extract (manufactured by Kyokuto Pharmaceutical Co., Ltd. or BD Co., Ltd.) and tryptone (manufactured by Hanai Co., Ltd.) are known to contain at least histidine, arginine, lysine, and cysteine.

[0021] Furthermore, regarding histidine, its oligomer has also been shown to have a control effect against root-knot nematodes, as demonstrated in the test results described later.

[0022] The pest control agent of the present invention may contain other additives in addition to the above-mentioned pest control component. Examples of other additives include fertilizers, pesticides, soil conditioners, plant activators, and plant growth regulators. The pest control agent may also be formulated using known additives. Examples of dosage forms include liquid formulations such as emulsions, wettable powders, water-soluble powders, suspensions, oils, and flowables; solid formulations such as powders, granules, tablets, microcapsules, and films; fumigants; fumigants, aerosols, etc. Examples of additives include carriers (diluents), surfactants, spreading agents, emulsifiers, wetting agents, dispersants, and disintegrants. As carriers for supporting the above-mentioned pest control component, inorganic and organic porous carriers such as zeolite, perlite, plant fiber, activated carbon, and diatomaceous earth can be used. Other pesticide active ingredients such as nematode control agents, antibacterial agents, insecticides, and herbicides other than the pest control component may also be used. As other nematode control agents, for example, a root-knot nematode control agent containing an extract of Bidens pilosa and wood vinegar as active ingredients may be mixed with the control agent of the present invention and used as a mixture or composition. The control agent of the present invention may also consist of the above control components alone.

[0023] <Pests to be controlled> While the main plant-parasitic nematodes that infest the roots of crops are root-knot nematodes, root-lesion nematodes, and cyst nematodes, this invention targets root-knot nematodes as the repellent, and in particular targets root-knot nematodes such as northern root-knot nematode (Meloidogyne hapla), sweet potato root-knot nematode (Meloidogyne incognita), Javan root-knot nematode (Meloidogyne javanica), and arenanaria root-knot nematode (Meloidogyne arenaria).

[0024] <Methods for controlling root-knot nematodes> The root-knot nematode control agent of the present invention can repel or control root-knot nematodes by being applied to soil or plants that are infested with root-knot nematodes. Examples of such plants include sweet potatoes, potatoes, bell peppers, eggplants, radishes, Chinese cabbage, taro, soybeans, strawberries, tomatoes, watermelons, melons, onions, peanuts, carrots, burdock, yams, corn, asparagus, and grapes. The soil is not limited to agricultural land; it may also be artificial fields or areas such as plant factories.

[0025] Any method can be used to apply the pest control agent of the present invention to soil such as farmland. In the case of a solid formulation, it can be sprayed, mixed, laid, or buried in the soil, while in the case of a liquid formulation, methods include drenching or mixing it into the soil, spraying it on the soil surface, or immersing plant roots or seeds in it. Any method and apparatus can be used for spraying or application. Alternatively, it may be mixed with pesticides or fertilizers and sprayed on farmland.

[0026] When applying the pest control agent of the present invention to the soil, the concentration of the pest control component should be adjusted to about 1 to 10,000 ppm, preferably 2 to 1,000 ppm. Using an irrigation device or the like, an amount of about 10 to 5,000 ml per plant per application should be applied daily to once a month during the cultivation period, depending on the plant's growth and the degree of damage.

[0027] The following examples of pest control agents will be specifically described by the following examples and comparative examples, but the present invention is not limited to these.

[0028] 1. Repellent effect against root-knot nematodes First, the following experiment was conducted to investigate the repellent behavior or control effects of various control components on sweet potato root-knot nematodes.

[0029] <Example 1: Histidine> As a control agent, L-histidine (hereinafter simply referred to as "histidine") was dissolved in 40% methanol to a concentration of 5 mg / ml. 0.1 ml of this solution was dropped onto a piece of filter paper and dried. The dried filter paper piece, used as a sample (0.5 mg of histidine), was placed on the left side of a petri dish containing gellan gum (manufactured by Nacalai Tesque), as shown in Figure 1. 8 to 16 sweet potato root-knot nematodes were sown at a position 1.2 cm away from the filter paper towards the center of the petri dish (sowing position). Sixteen hours after sowing, the behavior of the sweet potato root-knot nematodes was observed using a microscope (Nikon AZ100 Multizoom microscope).

[0030] Figure 2(a) is a micrograph showing the behavior of sweet potato root-knot nematodes in a sample without histidine (Control: comparative example), and Figure 2(b) is a micrograph showing the behavior of sweet potato root-knot nematodes in a sample with histidine. The black vertical area on the left edge of the photograph is a piece of filter paper, and the black area in the center is the area where the sweet potato root-knot nematodes were planted. The photographs were taken using a digital microscope camera (Flobel FR-400C), and then the images were stitched together to represent the entire petri dish. As shown in Figure 2(a), in the Control, the movement of the sweet potato root-knot nematodes covers the entire petri dish. This indicates that sweet potato root-knot nematodes exhibit random behavior. On the other hand, as shown in Figure 2(b), all sweet potato root-knot nematodes were observed to exhibit avoidance behavior, such as avoiding the histidine on the left side of the petri dish. This observation suggests that histidine is an effective control agent for sweet potato root-knot nematodes.

[0031] To quantitatively analyze the behavior of sweet potato root-knot nematodes, we scanned and quantified the nematode footprints in two areas: Area 1 (closer to the filter paper) partitioned to the left of the sowing site, and Area 2 (further from the filter paper) partitioned to the right of the sowing site. Each area measured 0.95 x 1.3 cm, and the distance between Area 1 and Area 2 was 0.27 cm. Specifically, we photographed each area 16 hours later using a digital microscope camera, and used the image analysis software ImageJ to quantify the extent to which sweet potato root-knot nematode movement had occurred in each area by counting the number of dots.

[0032] A similar experiment was performed on the control sample. The results obtained from image analysis are shown in the table in Figure 3. The relative quantities on the vertical axis in Figure 3 represent the area ratio of each region to the total area of ​​all regions in the movement trajectory of the sweet potato root-knot nematode. It can be seen that the sample containing 0.5 mg of histidine significantly repelled the sweet potato root-knot nematode compared to the control sample which did not contain histidine.

[0033] The same experiment was conducted with the amount of histidine in the sample changed to 0.1 mg and 0.01 mg, respectively. The results are also shown in the table in Figure 3. It was found that histidine significantly repelled sweet potato root-knot nematodes even at an amount of at least 0.1 mg.

[0034] <Example 2: Ornithine> The same experiment as in Example 1 was conducted, except that L-ornithine (hereinafter simply referred to as "ornithine") was used as the control agent. The same experiment was also conducted with the amount of ornithine in the sample changed to 0.1 mg and 0.01 mg, respectively. The results are shown in the table in Figure 4. It was found that ornithine significantly repelled sweet potato root-knot nematodes even at an amount of at least 0.1 mg.

[0035] <Example 3: Arginine> The same experiment as in Example 1 was conducted, except that L-arginine (hereinafter simply referred to as "arginine") was used as the control agent. The same experiment was also conducted with the amount of arginine in the sample changed to 0.1 mg and 0.01 mg, respectively. The results are shown in the table in Figure 5. It was found that arginine significantly repelled sweet potato root-knot nematodes even at an amount of at least 0.01 mg.

[0036] <Example 4: Lysine> The same experiment as in Example 1 was conducted, except that L-lysine (hereinafter simply referred to as "lysine") was used as the control agent. The same experiment was also conducted with different amounts of lysine in the sample: 0.1 mg, 0.01 mg, and 0.005 mg. The results are shown in the table in Figure 6. It was found that lysine significantly repelled sweet potato root-knot nematodes even at an amount of at least 0.005 mg.

[0037] <Example 5: Cysteine> The same experiment as in Example 1 was conducted, except that L-cysteine ​​(hereinafter simply referred to as "cysteine") was used as the control component. The same experiment was also conducted with different amounts of cysteine ​​in the sample: 0.1 mg, 0.05 mg, 0.01 mg, and 0.005 mg. The results are shown in the table in Figure 7. It was found that cysteine ​​significantly repelled sweet potato root-knot nematodes even at an amount of at least 0.005 mg.

[0038] <Example 6: Ascorbic Acid> The same experiment as in Example 1 was conducted, except that L-ascorbic acid (hereinafter simply referred to as "ascorbic acid") was used as the control agent. The same experiment was also conducted with the amount of ascorbic acid in the sample changed to 0.1 mg and 0.01 mg, respectively. The results are shown in the table in Figure 8. It was found that ascorbic acid significantly repelled sweet potato root-knot nematodes even at an amount of at least 0.01 mg.

[0039] <Example 7: Glucosamine> The same experiment as in Example 1 was conducted, except that D-glucosamine (hereinafter simply referred to as "glucosamine") was used as the control agent. The same experiment was also conducted with different amounts of glucosamine in the sample: 0.1 mg, 0.01 mg, and 0.005 mg. The results are shown in the table in Figure 9. It was found that even at an amount of at least 0.005 mg of glucosamine in the sample significantly repelled sweet potato root-knot nematodes.

[0040] <Example 8: 4-Hydroxyphenylacetic acid> The same experiment as in Example 1 was conducted, except that 4-hydroxyphenylacetic acid was used as the control agent. The same experiment was also conducted with the amount of 4-hydroxyphenylacetic acid in the sample changed to 0.1 mg and 0.01 mg, respectively. The results are shown in the table in Figure 10. It was found that 4-hydroxyphenylacetic acid significantly repelled sweet potato root-knot nematodes even at an amount of at least 0.5 mg.

[0041] <Example: Test using secretions from cellular slime molds of the genus Dictyostelium> As disclosed in Patent Document 4 (Japanese Patent No. 6172545), the present inventor has developed a repellent that repels root-knot nematodes, using a substance secreted from a cellular slime mold belonging to the genus Dictyostelium as the active ingredient. Experiments were conducted using 5 mg of this repellent under the same conditions as in the above examples. The control agent was prepared as follows, according to the method described in Japanese Patent Application Publication No. 2020-186233 disclosed by the same inventor.

[0042] Cells of the cellular slime mold Dictyostelium discoidium KAx3 strain were seeded into a flask containing synthetic medium HL-5. The cells were cultured by shaking at 150 rpm in a shaker until the cell count reached 1 x 10⁷ cells / ml (stationary phase). The cells and synthetic medium were separated by centrifugation of the cells and medium together. In the centrifuge tube, the medium became the supernatant, and the cells were pelleted at the bottom of the tube. To wash off the remaining medium from the cells, phosphate buffer was added to the centrifuge tube to suspend the cells, and the tube was centrifuged again. The supernatant was discarded, and phosphate buffer was added again to the centrifuge tube with the cells remaining at the bottom, and the cells were stirred to thoroughly suspend them. The cell concentration in the suspension was adjusted to 1 x 10⁸ cells / ml, and the mixture was transferred to a flask and cultured statically at 22°C for 72 hours. After this, the cells and medium were centrifuged to obtain the supernatant. This supernatant is called conditioned medium (hereinafter abbreviated as "CM"). The CM was dried using a rotary evaporator, its weight was measured, and it was dissolved in 40% methanol to a concentration of 100 mg / ml. This solution was then used to observe the repellent behavior of sweet potato root-knot nematodes.

[0043] Next, the concentrations of CM were adjusted to 50 mg / ml and 2 mg / ml, and 0.1 ml of each was soaked into a piece of filter paper, so that each piece of filter paper contained 5 mg and 0.2 mg of CM, and the same experiment was performed. The results are shown in Figure 11. From the graph in Figure 11, it can be seen that about 5 mg of secretion from cellular slime molds of the genus Dictyostelium is necessary to obtain a control effect. From these results, it can be said that even a small amount of the control component used in the above example is effective in controlling sweet potato root-knot nematodes.

[0044] <Example 9: Potato Peptone> The experiment was conducted in the same manner as in Example 1, except that potato peptone (manufactured by Kyokuto Pharmaceutical Industry Co., Ltd.) was used as the control agent, and the amount of potato peptone was changed to the values ​​in the range of 5.0 mg to 0.01 mg shown in Figure 19. For comparative samples, pure water (MilliQ) and CM prepared in the same manner as the above reference example were also used, and the content was changed to the values ​​in the range of 7.5 mg to 0.1 mg shown in Figure 19, and the experiment was conducted in the same manner as in Example 1. The results are shown in Figure 19. Even at a quantity of only 0.025 mg, potato peptone exceeded 70% in relative terms, indicating that it significantly repelled sweet potato root-knot nematodes. Considering that histidine, arginine, and lysine make up only about 13% of the amino acids contained in potato peptone, potato peptone can be a more effective control agent than the basic amino acids alone, even in small amounts, and is also preferable due to its easy availability.

[0045] <Example 10: Peptones other than potato peptone> The same experiment as in Example 1 was conducted, except that the control components used were bactopeptone (manufactured by BD), soybean peptone (manufactured by Solabia Biokar Diagnostics), Kyokuto peptone (manufactured by Kyokuto Pharmaceutical Industry Co., Ltd.), and Kyokuto yeast extract (manufactured by Kyokuto Pharmaceutical Industry Co., Ltd.), respectively. In this experiment, the amount of the control component in the samples was changed to 0.7 mg, 0.14 mg, and 0.028 mg, respectively. The results are shown in Figure 20. As comparative samples, the same experiment as in Example 1 was conducted on the same day using pure water (MilliQ), CM (3.5 mg, 0.7 mg, 0.14 mg) prepared in the same manner as the above reference example, and potato peptone (0.7 mg, 0.14 mg, 0.028 mg). Although the repellent effect was not as strong as that of potato peptone, it was found that all components except Kyokuto peptone significantly repelled sweet potato root-knot nematodes even at an amount of 0.14 mg (over 70% in relative terms).

[0046] Furthermore, on a different day from the above experiment, the same experiment as in Example 1 was conducted, except that proteose peptone (manufactured by BD), tryptone (manufactured by Hanai Co., Ltd.), and BD yeast extract (manufactured by BD) were used as samples, and the amounts of the control components were changed to 0.7 mg, 0.14 mg, and 0.028 mg, respectively. The results are shown in Figure 21. As comparative samples, the same experiment as in Example 1 was conducted on the same day using pure water (MilliQ) and CM prepared in the same manner as the above reference example (values ​​from 7.5 mg to 0.1 mg shown in Figure 21). A repellent effect was confirmed for all control components, and it was found that proteose peptone (manufactured by BD) and tryptone (manufactured by Hanai Co., Ltd.) significantly repelled sweet potato root-knot nematodes even at an amount of 0.14 mg (more than 70% in relative terms).

[0047] 2.Plant protection activity Next, the plant protection activity of Lotus corniculatus against sweet potato root-knot nematodes using the eight control components used in Examples 1 to 8 was investigated as follows.

[0048] First, 0.1 ml of the 5 mg / ml histidine (control component) sample prepared in Experimental Example 1 was soaked into a piece of filter paper cut in half from a 1 cm radius filter paper, and air-dried in a clean bench for 1 hour. As shown in Figure 12, three Lotus corniculatus plants were placed on an infection experiment plate at intervals of 35 mm, and the filter paper piece was placed 2 mm from the root of the Lotus corniculatus plant growing on the far left (Sample No. 1). Approximately 50 sweet potato root-knot nematodes were sown 1 cm away from the tip of the root of each Lotus corniculatus plant, and the plants were left to stand at 23°C for 48 hours. They were then immersed in 3% antiformin for 3 minutes. The roots were thoroughly washed with water, placed in the wells of a 6-well plate with acidic fuchsin stock added, and then heated in a 90°C constant temperature bath for 7 minutes. Afterward, the samples were allowed to cool at room temperature for 10 minutes, then immersed on a slide glass covered with acid-added glycerin, left to stand overnight at room temperature, and the stained sweet potato root-knot nematodes were crushed together with the roots of samples No. 1-3 using a coverslip. The number of infected nematodes was then counted visually.

[0049] Furthermore, the infection rates by sweet potato root-knot nematodes in the roots of Lotus corniculatus samples No. 1-3 are shown in the graph in Figure 13. In the control group, the number of sweet potato root-knot nematodes was almost the same in all samples, but when 0.5 mg of histidine was present on the filter paper, the number of sweet potato root-knot nematodes in sample No. 1 decreased significantly. This indicates that the sweet potato root-knot nematodes avoided invading the Lotus corniculatus roots that were close to the filter paper.

[0050] Similar plant protection activity experiments were conducted using filter paper containing a 5 mg sample (CM) of cellular slime mold secretion, as used in the above reference example. The results are also shown in the graph in Figure 13.

[0051] Similar plant protection activity experiments were conducted using 0.5 mg each of cysteine, ornithine, and lysine as control components. The results are shown in the graph in Figure 14. When these control components were present on the filter paper, the number of sweet potato root-knot nematodes in sample No. 1 was significantly reduced, indicating that the presence of these control components deterred the sweet potato root-knot nematodes from invading the roots of Lotus corniculatus. A similar experiment was also conducted using filter paper containing a 5 mg sample of cellular slime mold secretion. The results are shown in addition to the graph in Figure 14.

[0052] Similar plant protection activity experiments were conducted on the same day, with the control components changed to ascorbic acid and arginine, respectively. The results are shown in the graph in Figure 15. When these control components were present on the filter paper, the number of sweet potato root-knot nematodes in sample No. 1 decreased significantly, indicating that the presence of the control components deterred the sweet potato root-knot nematodes from invading the roots of Lotus corniculatus. A similar experiment was also conducted using filter paper containing a 5 mg sample of cellular slime mold secretion. The results are shown in addition to the graph in Figure 15.

[0053] Similar plant protection activity experiments were conducted using 4-hydroxyphenylacetic acid as the control agent. The results are shown in the graph in Figure 16. When the control agent was present on the filter paper, the number of sweet potato root-knot nematodes in sample No. 1 decreased significantly, indicating that the presence of the control agent deterred the sweet potato root-knot nematodes from invading the roots of Lotus corniculatus. A similar experiment was also conducted using filter paper containing a 5 mg sample of cellular slime mold secretion. The results are shown in addition to the graph in Figure 16.

[0054] Similar plant protection activity experiments were conducted using glucosamine as the control agent. The results are shown in the graph in Figure 17. When the control agent was present on the filter paper, the number of sweet potato root-knot nematodes in sample No. 1 decreased significantly, indicating that the presence of the control agent deterred the sweet potato root-knot nematodes from invading the roots of Lotus corniculatus. A similar experiment was also conducted using filter paper containing a 5 mg sample of secretion from cellular slime mold. The results are shown in addition to the graph in Figure 17. Note that the experimental results shown in Figures 13 to 17 were obtained on different days.

[0055] Similar plant protection activity experiments were conducted using potato peptone, the control component used in Example 9, as the sample. To investigate the effective amount of potato peptone, the amount of potato peptone in the sample was changed to 2.5 mg, 0.5 mg, 0.1 mg, and 0.025 mg, respectively. The results are shown in Figure 22. When at least 0.1 mg of potato peptone was present in the filter paper, the number of sweet potato root-knot nematodes in sample No. 1 was significantly reduced, indicating that the presence of potato peptone deterred the sweet potato root-knot nematodes from invading the roots of Lotus corniculatus. Similar experiments were also conducted using filter paper containing sterile water (DDW) and CM (3.5 mg), respectively. The results are shown in conjunction with the graph in Figure 22.

[0056] These experimental results indicate that applying control components or liquids containing them to the soil can effectively repel sweet potato root-knot nematodes that are present or attempting to invade the area.

[0057] 3. Repellent effect of oligomers of pest control components In Example 1, the effectiveness of histidine as a repellent against sweet potato root-knot nematodes was confirmed. In this example, the effect of histidine oligomers (hexamers) was also confirmed in the same manner as in the previous example. The results are shown in Figure 18. It can be seen that even an amount of 0.005 mg of histidine oligomer repels sweet potato root-knot nematodes. Furthermore, it is expected that using oligomers will make the control component less likely to decompose in the soil.

[0058] Although the present invention has been specifically described above with reference to examples, the present invention is not limited to these examples and also encompasses various modifications, improvements, and substitutions that can be made within the scope of the technical idea described in the claims. In the above examples and comparative examples, sweet potato root-knot nematodes were used as the target of control, but the control agent of the present invention has repellent activity not only against sweet potato root-knot nematodes but also against other root-knot nematodes, including northern root-knot nematodes. [Industrial applicability]

[0059] The root-knot nematode control agent of the present invention is readily available and can effectively repel root-knot nematodes even in small amounts without causing damage to crops or other organisms. Therefore, the present invention can increase crop productivity while maintaining the safety of crops and workers, and is expected to make a significant contribution to the agricultural field.

Claims

1. A root-knot nematode control agent containing at least one antioxidant component selected from the group consisting of cysteine, ascorbic acid, glucosamine, and hydroxyphenylacetic acid.

2. The root-knot nematode control agent according to claim 1, characterized in that the antioxidant component is cysteine ​​or ascorbic acid.

3. The root-knot nematode control agent according to claim 1, characterized in that the antioxidant component is glucosamine or hydroxyphenylacetic acid.

4. The root-knot nematode control agent according to any one of claims 1 to 3, further comprising an inorganic or organic carrier, wherein the antioxidant component is supported on the inorganic or organic carrier.

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