Application of naphthoquinone compound in preparation of nematode prevention and control medicament

Abstract

The invention belongs to the technical field of pest control, and particularly relates to application of naphthoquinone compounds in preparation of nematode control agents.The naphthoquinone compounds comprise 1, 2-naphthoquinone, 1, 4-naphthoquinone, 2-methyl-1, 4-naphthoquinone, 5-hydroxy-2-methyl-1, 4-naphthoquinone, 2-hydroxy-1, 4-naphthoquinone, 5-hydroxy-1, 4-naphthoquinone, 5, 8-dihydroxy-1, 4-naphthoquinone, 5, 8-dihydroxy-1, 4-naphthoquinone, 5, 8-dihydroxy-1, 4-naphthoquinone, 5, 8-dihydroxy-1, 4-naphthoquinone, 5, 8-dihydroxy-1, 4-naphthoquinone, 5, 8-dihydroxy-1, 4-naphthoquinone, 5, 8-dihydroxy-1, 4-naphthoquinone, the preparation method comprises the following steps of: adding menadione sodium hydrogen sulfite, 2-hydroxy-3-(3-methyl-2-butenyl)-1, 4-naphthoquinone, 2-methoxy-1, 4-naphthoquinone, 2-chloro-1, 4-naphthoquinone, 2, 3-dichloro-1, 4-naphthoquinone, 2-chloro-3-amino-1, 4-naphthoquinone, 2, 3-dichloro-5-nitro-1, 4-naphthoquinone, 2, 3-dichloro-6-nitro-1, 4-naphthoquinone, 5-amino-2, 3-dicyano-1, 4-naphthoquinone, 5, 8-dihydroxy-2, 3-dicyano-1, 4-naphthoquinone, 2, 3-dichloro-1, 4-naphthoquinone, 2, 3-dichloro-1, 4-naphthoquinone, 2-methoxy-1, 4-naphthoquinone, 2 The naphthoquinone compound provided by the invention can be separated and extracted from natural plants, is environment-friendly, pollution-free, residue-free and high in safety, has excellent nematode poisoning and prevention and control effects, and is beneficial to realizing green prevention and control.

Description

Technical Field

[0001] The invention belongs to the technical field of pest control, and specifically relates to the application of naphthoquinone compounds in the preparation of nematode control agents. Background Art

[0002] Plant parasitic nematodes are one of the most important pathogens causing plant diseases worldwide, and have created a huge burden for the sustainable development of modern agriculture. Currently, more than 3,000 plant species in the world are affected by nematodes, including potatoes, beans, sweet potatoes, cereals, bananas, beets and coconuts, etc. The global crop losses caused each year account for about 8.8%-14.6% of the total crop production, and cause huge economic losses worldwide. Pine wood nematodes, rice stem tip nematodes and sweet potato stem nematodes are notorious plant nematodes. As the direct pathogen of pine wood nematode disease, pine wood nematodes cause the most serious forest disaster in my country. Rice stem tip nematodes are an important and widely distributed pathogen that can cause rice "white tip" disease, which is estimated to cause huge economic losses worldwide every year. Sweet potato stem nematodes mainly damage the roots, shoots, stems and vines of sweet potatoes. Sweet potatoes suffer from 10% to 30% yield losses due to the damage of sweet potato stem nematodes, and up to 100% in severe cases of infection. Therefore, it is very necessary to provide a means to effectively control pine wood nematodes, rice stem nematodes and sweet potato stem nematodes.

[0003] The control of nematodes in the prior art mainly involves pine wood nematodes, rice stem nematodes, sweet potato stem nematodes and root-knot nematodes. The life cycle of pine wood nematodes includes three stages: eggs, larvae and adults. Pine wood nematodes mainly invade the interior of pine trees through the resin ducts of pine trees, feed on the parenchyma cells of pine trees, resulting in a decrease in the secretion of resin in pine trees, thereby causing symptoms such as yellowing, withering and falling of pine needles, and ultimately leading to the death of pine trees. However, pine wood nematodes mainly move inside pine trees, and the initial symptoms are not obvious, making it difficult to find and diagnose in time, and they are highly adaptable to the environment, can survive and reproduce under different climate and soil conditions, and are very difficult to control due to the characteristics of diverse transmission pathways and a wide host range. Rice stem nematodes hibernate in the husks of grains and between rice grains as adults and larvae, mainly harming the leaves and panicles of rice. After the seedlings are infected, the tips of the upper leaves gradually curl up to 2 to 4 cm and become white or gray, with a clear boundary between the diseased and healthy parts. The symptoms are obvious during the booting stage, and the tips of the sword leaves or the upper 2 or 3 leaves gradually wither and die 1 to 8 cm, turning yellow-brown or brown, slightly transparent, twisted, and with a clear brown boundary with the healthy part. The sweet potato stem nematode mainly parasitizes on tubers in the form of eggs, larvae and adults and overwinters in the cellar. It can also attach to diseased remains in the form of larvae and adults and overwinter in the soil and manure. It mainly harms tubers, followed by seedlings, the base of potato vines and thick roots, and does not harm leaves and fine roots. After being infected, the epidermis cracks and the internal chaff rots. In the middle and late stages of the disease, the tubers crack, the vines become short and deformed, and even die.

[0004] Chemical nematicides are the main means of controlling nematode diseases due to their diversity, rapid efficacy and ease of use. However, most nematicides have poor selectivity, high toxicity and impact on the environment and human safety, so more and more chemical nematicides are banned. Only individual products such as Fluopyram, Abamectin and Fosthiazate are allowed to be used. Natural products are abundant in resources, with diverse and unique skeletons, and have advantages such as broad-spectrum biological activity, low toxicity and environmental friendliness. Therefore, natural products have become an important arsenal for discovering new drugs and new pesticides. Patent application number KR1020190156769 provides a composition containing naphthoquinone compounds for controlling pine wood nematodes, but it specifically discloses the combined effect of 1,4-naphthoquinone, thujone and plumbagin. In addition, since the prepared thujone solution needs to be stored at -20°C, this undoubtedly increases the storage severity of the composition. In addition, plumbagin has anti-fertility effects and certain toxic side effects, which poses a great challenge to the residual control of the composition.

[0005] Therefore, finding a new type of pesticide with high safety, good activity, low residue, easy access and wide source is still a hot topic in green pesticide research. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention proposes the use of naphthoquinone compounds in the preparation of nematode control agents.

[0007] This is achieved specifically through the following technical solutions:

[0008] The present invention provides: application of naphthoquinone compounds in the preparation of nematode control agents, wherein the naphthoquinone compounds include 1,2-naphthoquinone, 1,4-naphthoquinone, 2-methyl-1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, menadione sodium bisulfite, 2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone, 2-methoxy- 1,4-naphthoquinone, 2-chloro-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2-chloro-3-amino-1,4-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, 2,3-dichloro-6-nitro-1,4-naphthoquinone, 5-amino-2,3-dicyano-1,4-naphthoquinone, 5,8-dihydroxy-2,3-dichloro-1,4-naphthoquinone, 2-(trans-4-(4-chlorophenyl)cyclohexyl)-3-hydroxynaphthalene-1,4-dione.

[0009] The nematodes refer to pine wood nematodes, rice stem nematodes and sweet potato stem nematodes.

[0010] The nematode control refers to poisoning the nematodes, inhibiting the hatching of nematode eggs, and inhibiting the feeding and reproduction capabilities of the nematodes.

[0011] Preferably, the naphthoquinone compounds include 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-chloro-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, and 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone.

[0012] Preferably, the naphthoquinone compound is 5,8-dihydroxy-1,4-naphthoquinone.

[0013] Specifically, the naphthoquinone compounds are used to prepare agents for killing pine wood nematodes, rice stem nematodes and sweet potato stem nematodes, pine wood nematode egg hatching inhibitors, and pine wood nematode feeding and reproduction ability inhibitors.

[0014] Further provided is the use of the aforementioned naphthoquinone compounds in the preparation of agents for killing pine wood nematodes, rice stem nematodes and sweet potato stem nematodes; the concentration of the naphthoquinone compounds is 12.5-200 μg / mL.

[0015] Further provided is the use of the aforementioned naphthoquinone compounds in the preparation of a pine wood nematode egg hatching inhibitor; the naphthoquinone compounds are used at a concentration of 2-100 μg / mL.

[0016] Furthermore, provided is the use of 5,8-dihydroxy-1,4-naphthoquinone in the preparation of a pine wood nematode egg hatching inhibitor.

[0017] Further provided is the use of the aforementioned naphthoquinone compounds in the preparation of pine wood nematode feeding and reproduction ability inhibitors; the use concentration of the naphthoquinone compounds is 10-20 μg / mL.

[0018] Furthermore, provided is the use of 5,8-dihydroxy-1,4-naphthoquinone in preparing an inhibitor of pine wood nematode feeding and reproduction ability.

[0019] Beneficial effects:

[0020] 1. Excellent nematode killing effect, achieving green control of nematodes. The 18 naphthoquinone compounds provided by the present invention have excellent anti-nematode activity against pine wood nematodes, rice stem tip nematodes and sweet potato stem nematodes. After in vitro nematicidal activity tests, the 18 naphthoquinone compounds can effectively kill pine wood nematodes, rice stem tip nematodes and sweet potato stem nematodes, thereby achieving green prevention and control of the above three nematode diseases, among which 1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-chloro-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone and 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone have nematicidal activity of 100% at a concentration of 200 μg / mL, and when the concentration is reduced to 50 μg / mL, the nematicidal activity can still reach more than 80.0%.

[0021] 2. Excellent nematode control effect, achieving green prevention of nematodes. The naphthoquinone compounds provided by the present invention can prevent nematodes by effectively inhibiting the hatching of eggs of pine wood nematodes and inhibiting the feeding and reproductive ability of pine wood nematodes.

[0022] 3. Raw materials are easy to obtain. Among the naphthoquinone compounds provided by the present invention, some compounds can be derived from nature or chemically synthesized, and are widely distributed in nature, and are distributed in plants and microorganisms. For example, 5-hydroxy-1,4-naphthoquinone can be isolated and extracted from natural plants such as Juglandia, Acer spp. and Juglans mandshurica; 1,4-naphthoquinone can be isolated and extracted from natural plants such as Impatiens, Juglandia and Boraginaceae; 5-hydroxy-2-methyl-1,4-naphthoquinone can be isolated and extracted from natural plants such as Polygonaceae, Polygonaceae, Plumbago and Purple Snow Flower; 5,8-dihydroxy-1,4-naphthoquinone can be isolated and extracted from natural plants such as Boraginaceae, Droseraceae and Nepenthes; 2-hydroxy-1,4-naphthoquinone is distributed in higher plants and microorganisms, especially in Lanceolata leaves.

[0023] 4. Among the naphthoquinone compounds provided by the present invention, some compounds can be separated and extracted from natural plants and belong to natural plant-derived compounds. Compared with traditional chemical nematicides, they are more environmentally friendly, less likely to produce resistance, pollution-free, residue-free, and highly safe when used as biological nematicides. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The effects of 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-chloro-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone and 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone on the activity of pine wood nematodes at different concentrations and time; A: The effect of 5-hydroxy-1,4-naphthoquinone on the activity of pine wood nematodes; B: The effect of 5,8-dihydroxy-1,4-naphthoquinone on the activity of pine wood nematodes; C: The effect of 2-chloro-1,4-naphthoquinone on the activity of pine wood nematodes; D: The effect of 2,3-dichloro-1,4-naphthoquinone on the activity of pine wood nematodes; E: The effect of 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone on the activity of pine wood nematodes;

[0025] Figure 2 The following are the effects of 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-chloro-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone and 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone on the activity of rice stem nematodes at different concentrations and time; A: The effect of 5-hydroxy-1,4-naphthoquinone on the activity of rice stem nematodes; B: The effect of 5,8-dihydroxy-1,4-naphthoquinone on the activity of rice stem nematodes; C: The effect of 2-chloro-1,4-naphthoquinone on the activity of rice stem nematodes; D: The effect of 2,3-dichloro-1,4-naphthoquinone on the activity of rice stem nematodes; E: The effect of 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone on the activity of rice stem nematodes;

[0026] Figure 3 The effects of 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-chloro-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone and 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone on the activity of sweet potato stem nematodes at different concentrations and time; A: The effect of 5-hydroxy-1,4-naphthoquinone on the activity of sweet potato stem nematodes; B: The effect of 5,8-dihydroxy-1,4-naphthoquinone on the activity of sweet potato stem nematodes; C: The effect of 2-chloro-1,4-naphthoquinone on the activity of sweet potato stem nematodes; D: The effect of 2,3-dichloro-1,4-naphthoquinone on the activity of sweet potato stem nematodes; E: The effect of 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone on the activity of sweet potato stem nematodes;

[0027] Figure 4This is a comparison chart of the effect of 5,8-dihydroxy-1,4-naphthoquinone on inhibiting the hatching of pine wood nematode eggs; SPSS was used to perform variance analysis on the data in the figure, and different letters indicate significant differences (P<0.05);

[0028] Figure 5 This is a comparison chart of the effect of 5,8-dihydroxy-1,4-naphthoquinone in inhibiting the feeding and reproductive capacity of pine wood nematodes; wherein, A: the feeding amount of pine wood nematodes; B: the reproductive capacity of pine wood nematodes. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are further described in detail below, but the present invention is not limited to these embodiments, and any improvement or substitution based on the basic spirit of the present embodiment still falls within the scope of protection required by the claims of the present invention.

[0030] Example 1

[0031] This embodiment provides the use of 18 naphthoquinone compounds in the preparation of agents for controlling pine wood nematodes, rice stem nematodes and sweet potato stem nematodes, and the naphthoquinone compounds are shown in Table 1;

[0032] Table 118 names and structures of naphthoquinone compounds

[0033]

[0034]

[0035] The agent for preventing and controlling pine wood nematodes, rice stem nematodes and sweet potato stem nematodes includes the functions of poisoning the nematodes, inhibiting the hatching of nematode eggs, and inhibiting the feeding and reproduction capabilities of the nematodes.

[0036] Experimental Example 2

[0037] As shown in Table 1, naphthoquinone compounds have toxic effects on pine wood nematodes, rice stem nematodes and sweet potato stem nematodes.

[0038] 1. The naphthoquinone compounds shown in Table 1 were used to test the in vitro nematicidal activity. The specific experimental method was as follows: pine wood nematodes, rice stem nematodes and sweet potato stem nematodes of 2-4 instars cultured in potato glucose agar-Botrytis cinerea were used as test objects. All compounds were systematically tested for nematicidal biological activity using an in vitro nematicidal method. All compounds were tested at concentrations of 200 and 50 μg / mL, and a 1% Tween 80 aqueous solution without any compound was used as a negative control. 10 μL of nematode suspension (about 50) and 300 μL of the treatment group test solution were added to the corresponding 48-well plates, with three parallels for each treatment. The 48-well plates were placed in a biochemical incubator at 27°C for light protection. After 48 hours, the death of nematodes was observed and counted (the nematodes were considered dead when their bodies were straight or they remained motionless after being touched with a needle). The corrected mortality rate of nematodes was calculated using the following formula:

[0039] Corrected mortality rate (%) = (mortality rate of treatment group – mortality rate of control group) / (1 – mortality rate of control group)×100.

[0040] The results are shown in Table 2;

[0041] Table 2 Nematicidal activity of naphthoquinone compounds at different concentrations a

[0042]

[0043]

[0044] Note: a Each experiment was repeated three times; b Flu stands for fluopyram.

[0045] As shown in Table 2, all 18 naphthoquinone compounds have certain nematicidal activity. Among them, the nematicidal activity of compounds 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-chloro-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone and 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone at a concentration of 200 μg / mL reached 100%. When the concentration was reduced to 50 μg / mL, the insecticidal activity could still reach more than 80.0%.

[0046] 2. Determine the effect of compounds on nematode activity at different concentrations and time

[0047] The specific operation is as follows: the test concentrations of the compound are configured to be 200, 100, 50, 25, and 12.5 μg / mL, respectively, and the treatment time is 0, 3, 6, 12, 24, and 48 h, respectively. Then, a 1% Tween 80 aqueous solution without any compound is used as a control.

[0048] Experimental results:

[0049] The results are as follows Figure 1 As shown in Figures 2 and 3, when the concentration of the compound is 200 μg / mL, 5-hydroxy-1,4-naphthoquinone can kill all larvae within 3 hours; 5,8-dihydroxy-1,4-naphthoquinone can kill all pine wood nematodes within 6 hours, and all rice stem nematodes and sweet potato stem nematodes within 12 hours; 2-chloro-1,4-naphthoquinone can kill all pine wood nematodes and rice stem nematodes within 6 hours, and all sweet potato stem nematodes within 3 hours; 3,4-dichloro-5,8-dihydroxy-1,4-naphthoquinone and 2,3-chloro-1,4-naphthoquinone can kill all larvae within 24 hours.

[0050] Example 3

[0051] The naphthoquinone compounds shown in Table 1 inhibit the hatching of pine wood nematode eggs.

[0052] Experimental method: 5,8-dihydroxy-1,4-naphthoquinone (Compound 7) with concentrations of 100, 50, 25, 10, 5 and 2 μg / mL was prepared as the test solution by the reference method. Fluopyram test solution with the same concentration was prepared as the positive control by the same method, and 1% Tween 80 without any compound was used as the negative control. 50uL of nematode suspension (containing about 100-200 eggs) and the test solution (300uL) were added to a 48-well biochemical culture plate, and cultured in a biochemical incubator at 27°C in the dark. After the eggs of the CK group were almost completely hatched, the number of nematode eggs hatched at different concentrations was observed and counted, and the hatching rate was calculated according to the following formula:

[0053] Nematode hatching rate (%) = (number of larvae / (number of eggs + number of larvae)) × 100%

[0054] Experimental results:

[0055] The results are as follows Figure 4 As shown in the results, high concentrations of 5,8-dihydroxy-1,4-naphthoquinone can inhibit the hatching of pine wood nematode eggs. The hatching rate of pine wood nematode eggs in the CK group was 98.3%, while the hatching rate of pine wood nematode eggs treated with 100 μg / mL 5,8-dihydroxy-1,4-naphthoquinone was 9.4%. However, as the concentration of compound 7 decreased, the hatching rate of pine wood nematode eggs gradually increased. When the concentration of 5,8-dihydroxy-1,4-naphthoquinone dropped to 10 μg / mL, the hatching rate of pine wood nematode eggs was only 41.7%, which was comparable to fluopyram. However, when the concentration dropped to 5 and 2 μg / mL, 5,8-dihydroxy-1,4-naphthoquinone was better than fluopyram in inhibiting the hatching of pine wood nematode eggs.

[0056] Example 4

[0057] The naphthoquinone compounds shown in Table 1 inhibit the feeding and reproductive ability of pine wood nematodes.

[0058] Experimental method: Pine wood nematodes were cultured in a biochemical incubator at 27°C in the dark with 5,8-dihydroxy-1,4-naphthoquinone and fluopyram at concentrations of 10, 15 and 20 μg / mL for 48 hours. Then, the nematodes in each treatment group were rinsed three times with sterile water, and pine wood nematodes (about 20) were randomly selected and inoculated into the center of a culture dish full of Botrytis cinerea. Cultured in the dark at 27°C. When the Botrytis cinerea in the culture dish of the negative control group (CK) was completely consumed by the nematodes, the feeding of the nematodes was observed and the number of reproduction was calculated.

[0059] Experimental results:

[0060] The results are as follows Figure 5 As shown in the figure, 5,8-dihydroxy-1,4-naphthoquinone has a good inhibitory effect on the feeding and reproduction ability of pine wood nematodes. As the concentration of 5,8-dihydroxy-1,4-naphthoquinone increases, the area where the hyphae disappear gradually decreases, that is, the ability of the nematodes to engulf the hyphae of Botrytis cinerea gradually decreases ( Figure 5 A), the hyphae of Botrytis cinerea in the CK group completely disappeared after 10 days of culture (completely devoured by nematodes). When the concentration of 5,8-dihydroxy-1,4-naphthoquinone was 20μg / mL, the area of ​​hyphae disappearance was very small, indicating that 5,8-dihydroxy-1,4-naphthoquinone had an excellent inhibitory effect on the feeding of pine wood nematodes. In addition, compared with the CK group, 5,8-dihydroxy-1,4-naphthoquinone at concentrations of 10, 15 and 20μg / mL was able to significantly reduce the reproductive capacity of pine wood nematodes ( Figure 5 B), for example, at a concentration of 20 μg / mL, the relative reproductive capacity of 5,8-dihydroxy-1,4-naphthoquinone against pine wood nematodes was only 11.1%.

[0061] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. The use of naphthoquinone compounds in the preparation of nematode control agents, characterized in that: The naphthoquinone compounds include 1,2-naphthoquinone, 1,4-naphthoquinone, 2-methyl-1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, menadione sodium bisulfite, 2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone, 2-methoxy-1,4-naphthoquinone, 2-chloro-1, 4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2-chloro-3-amino-1,4-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, 2,3-dichloro-6-nitro-1,4-naphthoquinone, 5-amino-2,3-dicyano-1,4-naphthoquinone, 5,8-dihydroxy-2,3-dichloro-1,4-naphthoquinone, 2-(trans-4-(4-chlorophenyl)cyclohexyl)-3-hydroxynaphthalene-1,4-dione.

2. The use of the naphthoquinone compound according to claim 1 in the preparation of a nematode control agent, characterized in that: The nematodes refer to pine wood nematodes, rice stem nematodes and sweet potato stem nematodes.

3. The use of the naphthoquinone compound according to claim 1 in the preparation of a nematode control agent, characterized in that: The nematode control refers to poisoning the nematodes, inhibiting the hatching of nematode eggs, and inhibiting the feeding and reproduction capabilities of the nematodes.

4. The use of the naphthoquinone compound according to claim 1 in the preparation of a pine wood nematode egg hatching inhibitor, characterized in that: The naphthoquinone compounds include 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-chloro-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, and 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone.

5. Use of the naphthoquinone compound according to claim 1 or 4 in the preparation of a pine wood nematode egg hatching inhibitor, characterized in that: The naphthoquinone compound is 5,8-dihydroxy-1,4-naphthoquinone.

6. Use of the naphthoquinone compound according to claim 1 in the preparation of a nematode control agent, characterized in that: The naphthoquinone compound is used for preparing an agent for killing pine wood nematodes, rice stem nematodes and sweet potato stem nematodes, and the concentration of the naphthoquinone compound is 12.5-200 μg / mL.

7. Use of the naphthoquinone compound according to claim 1 in the preparation of a nematode control agent, characterized in that: The naphthoquinone compound is used for preparing a pine wood nematode egg hatching inhibitor, and the concentration of the naphthoquinone compound is 2-100 μg / mL.

8. The use of the naphthoquinone compound according to claim 1 in the preparation of a nematode control agent, characterized in that: The naphthoquinone compound is used for preparing the pine wood nematode feeding and reproduction ability inhibitor, and the concentration of the naphthoquinone compound is 10-20 μg / mL.

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