阅读说明：本技术 一种阿维菌素微囊悬浮剂及其制备方法 (Abamectin microcapsule suspending agent and preparation method thereof ) 是由 宋涛 宋伟杰 高志山 胡兆平 徐文华 滕美丽 于 2021-09-24 设计创作，主要内容包括：本发明涉及一种阿维菌素微囊悬浮剂及其制备方法。所述阿维菌素微囊悬浮剂由下列重量百分比的组分组成：阿维菌素2～10％,溶剂10～35％,壁材2～10％,乳化剂3～4％,分散剂3～9％,稳定剂0.1～2％,消泡剂0.01～0.1％,补足水至100％。本发明还提供上述阿维菌素微囊水悬浮剂的制备方法。本发明提供的阿维菌素微囊水悬浮剂以聚氨酯多元异氰酸酯单体或改性多元异氰酸酯与天然高分子固化剂形成的聚氨酯或聚脲作为壁材,具有生物降解性能好,也是一种很好的植物促生物质,具有良好的加工稳定性、贮藏稳定性、防紫外光分解稳定性和极高的包覆率,并且制备得到微囊粒径小且分布均一,集中分布在2～3μm。(The invention relates to an abamectin microcapsule suspending agent and a preparation method thereof. The abamectin microcapsule suspending agent consists of the following components in percentage by weight: 2-10% of abamectin, 10-35% of solvent, 2-10% of wall material, 3-4% of emulsifier, 3-9% of dispersant, 0.1-2% of stabilizer, 0.01-0.1% of defoamer and water for supplementing to 100%. The invention also provides a preparation method of the abamectin microcapsule water suspending agent. The avermectin microcapsule water suspending agent provided by the invention takes polyurethane or polyurea formed by polyurethane polybasic isocyanate monomer or modified polybasic isocyanate and natural polymer curing agent as a wall material, has good biodegradation performance, is also a good plant growth promoting substance, has good processing stability, storage stability, ultraviolet light decomposition prevention stability and extremely high coating rate, and the prepared microcapsule has small and uniform particle size and is distributed in 2-3 mu m in a centralized way.)

1. The avermectin microcapsule suspending agent is characterized by comprising the following components in percentage by weight: 2-10% of abamectin, 10-35% of solvent, 2-10% of wall material, 3-4% of emulsifier, 3-9% of dispersant, 0.1-2% of stabilizer, 0.01-0.1% of defoamer and water for supplementing to 100%.

2. The abamectin microcapsule suspension of claim 1, wherein the solvent is one or a mixture of two or more of dichloromethane, N-dimethylformamide, chloroform, sec-butyl acetate, and cyclohexanone.

3. The abamectin microcapsule suspension of claim 1, wherein the wall material is polyurethane or polyurea formed by a polyisocyanate monomer or a modified polyisocyanate monomer and a natural polymer curing agent.

4. The avermectin microcapsule suspension of claim 3, wherein the polyisocyanate monomer is one or a mixture of two or more of hexamethylene diisocyanate, diphenylmethane-4, 4 '-diisocyanate, 1, 5-naphthalene diisocyanate, toluene-2, 4-diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate.

5. The avermectin microcapsule suspension of claim 3, wherein the modified polyisocyanate monomer is one or a mixture of two or more of polyol, polyamine, polyether-modified toluene-2, 4-diisocyanate, diphenylmethane-4, 4 '-diisocyanate, isophorone diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate.

6. The abamectin microcapsule suspension as claimed in claim 1, wherein the natural polymer curing agent is one or a mixture of more than two of chitosan, carboxymethyl chitosan, chitosan oligosaccharide, etherified modified chitosan, esterified modified chitosan, modified polyglutamic acid and modified small molecule active peptide.

7. The abamectin microcapsule suspension as claimed in claim 1, wherein the emulsifier is one or a mixture of more than two of EO-PO block copolymer, fatty alcohol-polyoxyethylene ether, and alkylphenol polyoxyethylene ether phosphate;

the dispersing agent is one or a mixture of more than two of tristyrylphenol polyoxyethylene ether, sorbitol monolaurate polyoxyethylene ether, naphthalenesulfonate formaldehyde condensate sulfonate, sodium lignosulfonate, calcium lignosulfonate, polyvinylpyrrolidone, sodium dodecyl sulfonate and sodium polycarboxylate.

8. The abamectin microcapsule suspending agent according to claim 1, wherein the stabilizer is one or a mixture of more than two of xanthan gum, polyacrylamide and polyvinyl alcohol; the defoaming agent is one or a mixture of more than two of long-chain fatty alcohol, fatty acid ester, tributyl phosphate, polyether and polyether modified organic silicon.

9. The preparation method of the abamectin microcapsule water suspending agent as claimed in claim 3, which is characterized by comprising the following steps:

weighing the components according to the proportion, dissolving the abamectin in a solvent, adding a polybasic isocyanate monomer or a modified polybasic isocyanate monomer, and uniformly mixing to obtain an oil phase; adding an emulsifier and a dispersant into water, and uniformly mixing to obtain a water phase; adding the oil phase into the water phase under high-speed shearing dispersion to form an oil-in-water emulsion; and adding a natural polymer curing agent into the oil-in-water emulsion under stirring, reacting for 1-3 h at 40-60 ℃, continuously adding a stabilizer and a defoaming agent, stirring and dispersing uniformly, and heating and preserving heat to form a capsule to obtain the abamectin microcapsule water suspending agent.

10. The method of claim 9, wherein the high shear rate is 4000 to 11000 rpm; further preferably 7000 to 9000 rpm; the stirring speed is 300-400 rpm, the heating temperature is 40-60 ℃, and the heat preservation time is 2-4 h.

Technical Field

The invention relates to an abamectin microcapsule suspending agent and a preparation method thereof, belonging to the technical field of pesticides.

Background

Root-knot nematodes are plant parasitic nematode diseases which are extremely difficult to control, and the host range of the plant parasitic nematode is more than 3000 plants, so that the yield can be reduced by 10-20% generally, and can reach 30-40% in severe cases, even the plant parasitic nematode is out of date. The economic loss caused by nematodes reaches billions each year, and the root-knot nematodes become one of serious obstacles influencing the yield and quality of agricultural products. The traditional control method mainly takes chemical control as a main part, and high-toxicity pesticides occupy an important position, but along with the enhancement of environmental awareness of people and the higher requirement on the safety of agricultural products, some high-toxicity pesticides are forbidden to be used one after another, at present, the control agents for root knot nematode are fewer, and only have abamectin, fosthiazate and other agents.

Abamectin (Abamectin) is a natural product separated from soil microorganisms, is a hexadecanolide disaccharide compound, and has the effects of contact killing and stomach poisoning on insects and mites by interfering a special insecticidal mechanism of nerve conduction of pests. In recent years, abamectin as a nematicide is widely applied to agricultural production and has quite remarkable effect. At present, the traditional formulations such as granules, missible oil, water dispersible granules and the like are mainly used, but due to the special pesticide application environment of soil, the avermectin has strong photolysis and short residual period, so that the pesticide release time and the residual period are short, the pesticide effect is seriously influenced, and the environment pollution is serious. Therefore, how to prolong the release time and the duration of the drug effect of the abamectin becomes a key problem for the application research of the abamectin.

Microencapsulation is an effective way to improve the use efficiency of the avermectin. Microcapsule suspensions are one of the new formulations of pesticides that are clearly specified and developed in the policy of the pesticide industry in China. The dosage form takes high molecular material as the capsule wall, and the pesticide active substance is wrapped by a chemical, physical or physical-chemical method to form a microcapsule with a semipermeable capsule membrane, which can control the release speed of the pesticide active substance within a certain time and has the characteristics of long lasting time, low toxicity to the environment and human body, good stability of active ingredients, safe use and the like. Therefore, the avermectin is prepared into the microcapsule suspending agent, so that the use of organic solvents can be reduced, the production cost is reduced, and the microcapsule suspending agent has a slow release function and is more environment-friendly. Interfacial polymerization is one of the most common methods for preparing pesticide microcapsules, and because the process is simple, the capsule core-shell ratio of the microcapsules is large and reaches more than 10:1, the cost is low, and about 90 percent of the current commercial pesticide microcapsules are produced by adopting the method. From the view point of microencapsulation wall materials, most wall materials used by the interfacial polymerization method are synthetic or semi-synthetic polymer materials, and have the defects of poor biodegradability, environmental pollution and the like.

Chinese patent document CN109497057A discloses an avermectin B2 microcapsule suspending agent for preventing and treating root-knot nematodes and a preparation method thereof, the avermectin B2 microcapsule suspending agent can be prepared into an avermectin B2 microcapsule water suspending agent or an avermectin B2 microcapsule oil suspending agent, polyurethane, polyurea, chitosan and modified chitosan are respectively used as wall materials, and two water-based and oil-based microcapsule suspending agents are prepared by three different methods. In the first method, polyurethane and polyurea are used as wall materials to prepare the avermectin microcapsule water suspending agent, and the polyurethane and polyurea are high-molecular synthetic materials, so that the defects of poor biodegradability and environmental pollution exist; the second method takes modified chitosan as a wall material, the prepared avermectin microcapsule water suspension has relatively large particle size and uneven distribution, and has the defects of complex process and high cost due to the need of vacuum distillation of a solvent for post-treatment; the microcapsule prepared by the third method needs a large amount of organic solvent, and a three-phase system is formed, so that the defects of complex process and high industrial production cost exist.

In summary, the prior art has the following disadvantages: the existing traditional abamectin preparation has the characteristics of strong photodegradability of abamectin, short drug release time and lasting period, and serious environmental pollution caused by adopting a large amount of organic solvent for dissolution. And the adopted polyurethane and polyurea wall materials are synthesized by using polyol or polyamine as a curing agent, so that the defects of poor biodegradability and environmental pollution exist. Meanwhile, in the existing wall material production process, some processes are complex and tedious, the production cost is greatly increased, and some processes need to use a large amount of organic solvents, so that a series of problems of environment pollution, difficulty in solvent treatment in the later period and the like are necessarily caused.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an abamectin microcapsule suspending agent and a preparation method thereof.

The technical scheme of the invention is as follows:

an abamectin microcapsule suspending agent is composed of the following components in percentage by weight: 2-10% of abamectin, 10-35% of solvent, 2-10% of wall material, 3-4% of emulsifier, 3-9% of dispersant, 0.1-2% of stabilizer, 0.01-0.1% of defoamer and water for supplementing to 100%.

According to the invention, the solvent is preferably one or a mixture of more than two of dichloromethane, N-dimethylformamide, trichloromethane, sec-butyl acetate and cyclohexanone.

According to the invention, the wall material is preferably polyurethane or polyurea formed by a polyisocyanate monomer or a modified polyisocyanate monomer and a natural polymer curing agent.

According to the present invention, the polyisocyanate monomer is preferably one or a mixture of two or more of hexamethylene diisocyanate, diphenylmethane-4, 4 '-diisocyanate, 1, 5-naphthalene diisocyanate, toluene-2, 4-diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and 4, 4' -dicyclohexylmethane diisocyanate.

According to the invention, the modified polyisocyanate monomer is preferably one or a mixture of more than two of polyol, polyamine, polyether modified toluene-2, 4-diisocyanate, diphenylmethane-4, 4 '-diisocyanate, isophorone diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate.

According to the invention, preferably, the natural polymer curing agent is one or a mixture of more than two of chitosan, carboxymethyl chitosan, chitosan oligosaccharide, etherified modified chitosan, esterified modified chitosan, modified polyglutamic acid and modified small molecule active peptide.

According to the invention, the emulsifier is preferably one or a mixture of more than two of EO-PO block copolymer, fatty alcohol-polyoxyethylene ether and alkylphenol polyoxyethylene ether phosphate.

According to the invention, the dispersing agent is preferably one or a mixture of more than two of tristyrylphenol polyoxyethylene ether, sorbitol monolaurate polyoxyethylene ether, naphthalene sulfonate formaldehyde condensate sulfonate, sodium lignosulfonate, calcium lignosulfonate, polyvinylpyrrolidone, sodium dodecyl sulfonate and polycarboxylic acid sodium salt.

According to the invention, the stabilizer is preferably one or a mixture of more than two of xanthan gum, polyacrylamide and polyvinyl alcohol.

According to the invention, the defoaming agent is preferably one or a mixture of more than two of long-chain fatty alcohol, fatty acid ester, tributyl phosphate, polyether and polyether modified organic silicon.

The invention also provides a preparation method of the abamectin microcapsule water suspending agent, which comprises the following steps:

weighing the components according to the proportion, dissolving the abamectin in a solvent, adding a polybasic isocyanate monomer or a modified polybasic isocyanate monomer, and uniformly mixing to obtain an oil phase; adding an emulsifier and a dispersant into water, and uniformly mixing to obtain a water phase; adding the oil phase into the water phase under high-speed shearing dispersion to form an oil-in-water emulsion; and adding a natural polymer curing agent into the oil-in-water emulsion under stirring, reacting for 1-3 h at 40-60 ℃, continuously adding a stabilizer and a defoaming agent, stirring and dispersing uniformly, and heating and preserving heat to form a capsule to obtain the abamectin microcapsule water suspending agent.

According to the invention, the high-speed shearing speed is preferably 4000-11000 rpm; further preferably 7000 to 9000 rpm.

According to the invention, the stirring speed is 300-400 rpm, the heating temperature is 40-60 ℃, and the heat preservation time is 2-4 h.

The invention has the following beneficial effects:

1. the avermectin microcapsule water suspending agent provided by the invention takes polyurethane or polyurea formed by polyurethane polybasic isocyanate monomer or modified polybasic isocyanate and natural polymer curing agent as the wall material, compared with the wall material adopted by the existing microcapsule polymerization, the avermectin microcapsule water suspending agent has good biodegradation performance, is a good plant growth promoting substance, has simple production process and easy process, greatly reduces production cost, does not need to use a large amount of organic solvent, does not pollute the environment, and does not relate to a series of problems of later solvent treatment and the like.

2. The abamectin microcapsule water suspension preparation prepared by the invention has good processing stability, storage stability, ultraviolet light decomposition prevention stability and extremely high coating rate, and the prepared microcapsule has small and uniform particle size, is intensively distributed at 2-3 mu m, can effectively prolong the release time and the pesticide effect duration of abamectin, and enhances the capability and time of preventing and controlling nematodes.

Detailed Description

The technical solution of the present invention will be further described with reference to the following specific examples.

The modified polyglutamic acid in the examples is available from Nanjing Xuanyi Bio Inc.; modified small molecule active peptide Angel Yeast Co., Ltd is available.

Example 1

TABLE 1 5% Abamectin B2 microcapsule suspension agent each component dosage

Item	Components	Content (%)
			Active ingredient	Abamectin B2	5.0
Solvent(s)	Trichloromethane	25.0
			Emulsifier	EO-PO block copolymer Y-1	3.0
Dispersing agent	Polyvinylpyrrolidone	1.0
			Wall material main body	Modified toluene-2, 4-diisocyanate	2.5
Natural polymer curing agent	Esterification modified chitosan	2.0
			Stabilizer	Polyvinyl alcohol	0.3
Defoaming agent	Polyether 1213	0.1
			Water (W)	Deionized water	61.1

The preparation method of the abamectin microcapsule suspension preparation comprises the following steps:

mixing 5g of abamectin B2 raw drug with 25g of trichloromethane to dissolve the raw drug, adding 2.5g of modified toluene-2, 4-diisocyanate, and uniformly stirring and mixing to obtain an oil phase; dissolving 3g of EO-PO block copolymer Y-1 and 1g of polyvinylpyrrolidone in 61.1g of deionized water to obtain a water phase; the oil phase was poured into the water phase at a shear rate of 8000rpm to give an O/W emulsion. Dropwise adding the esterified modified chitosan solution into the emulsion at 300rpm, heating the system to 50 ℃ after the dropwise adding is finished, preserving the temperature for 2 hours, and reacting to the end point; adding 0.3g of polyvinyl alcohol and 0.1g of polyether 1213, stirring and dispersing uniformly, and keeping the temperature at 50 ℃ for 3 hours to obtain the 5% avermectin B2 chitosan polyurethane-based microcapsule water suspending agent.

Example 2

TABLE 2 5% Abamectin B2 microcapsule suspension agent component dosage

The preparation method of the abamectin microcapsule suspension preparation comprises the following steps:

mixing 5g of abamectin B2 raw drug with 20g of dimethylbenzene to dissolve the raw drug, adding 2.5g of modified xylylene diisocyanate, and uniformly stirring and mixing to obtain an oil phase; dissolving 4g of fatty alcohol-polyoxyethylene ether and 1g of naphthalene sulfonate formaldehyde condensate sulfonate in 65.1g of deionized water to obtain a water phase; at a shear rate of 10000rpm, the oil phase was poured into the aqueous phase to obtain an O/W emulsion. Dropwise adding a modified polyglutamic acid solution into the emulsion at 300rpm, heating the system to 50 ℃ after dropwise adding, preserving heat for 2 hours, and reacting to the end point; adding 0.3g of xanthan gum and 0.1g of organic silicon 0213, stirring and dispersing uniformly, and keeping the temperature at 40 ℃ for 4 hours to obtain the 5% abamectin B2 polyglutamic acid polyureido microcapsule water suspending agent.

Example 3

TABLE 3 5% Abamectin B2 microcapsule suspension agent component dosage

Item	Components	Content (%)
			Active ingredient	Abamectin B2	5.0
Solvent(s)	Toluene	20.0
			Emulsifier	Alkyl phenol polyoxyethylene ether phosphate	3.5
Dispersing agent	Lignosulfonic acid sodium salt	1.0
			Wall material main body	Modified isophorone diisocyanateEsters	3.0
Natural polymer curing agent	Modified small molecule active peptide	1.5
			Stabilizer	Polyacrylamide	0.3
Defoaming agent	Phosphoric acid tributyl ester	0.1
			Water (W)	Deionized water	65.6

The preparation method of the abamectin microcapsule suspension preparation comprises the following steps:

mixing 5g of abamectin B2 technical product with 20g of toluene to dissolve the technical product, adding 3g of modified isophorone diisocyanate, and stirring and mixing uniformly to obtain an oil phase; dissolving 3.5g of alkylphenol polyoxyethylene phosphate and 1g of sodium lignin sulfonate in 65.6g of deionized water to obtain a water phase; at a shear rate of 10000rpm, the oil phase was poured into the aqueous phase to obtain an O/W emulsion. Dropwise adding the modified small molecule active peptide solution into the emulsion at 300rpm, heating the system to 50 ℃ after the dropwise adding is finished, preserving the heat for 2 hours, and reacting to the end point; adding 0.3g of polyacrylamide and 0.1g of tributyl phosphate, stirring and dispersing uniformly, and keeping the temperature at 60 ℃ for 2 hours to obtain the 5% abamectin B2 polypeptide polyurethane-based microcapsule water suspending agent.

Test example 1

Respectively storing the abamectin B2 microcapsule suspending agent prepared in the embodiment 1-3, the conventional microcapsule suspending agent 1 and the conventional microcapsule suspending agent 2 at 54 +/-2 ℃ for 14 days, at 0 +/-2 ℃ for 7 days and at a dominant wavelength of 254nm, and continuously irradiating the prepared microcapsule suspending agent for 24 hours under an ultraviolet lamp at a lamp distance of 15 cm; then, the content of the abamectin B2 is tested, and the test result is shown in Table 4. The conventional microcapsule suspending agent 1 is prepared by taking polyurethane as a wall material, and the conventional microcapsule suspending agent 2 is prepared by taking chitosan as a wall material.

The content of abamectin is determined by high performance liquid chromatography.

TABLE 4 results of Avermectin B2 microcapsule suspension stability test

Processing decomposition rate (%) (effective component input amount-fresh and not stored effective component actual measurement) during preparation)/effective component input amount × 100 during preparation

The thermal storage decomposition rate (%) - (the input amount of the effective component during preparation-the actual measurement of the effective component after thermal storage)/the input amount of the effective component during preparation x 100

Ultraviolet decomposition rate (%) - (input of active ingredient-actual measurement of active ingredient after ultraviolet lamp irradiation) at the time of preparation/input of active ingredient at the time of preparation × 100

Encapsulation ratio (%) - (amount of active ingredient charged-effective ingredient in the capsule measured)/amount of active ingredient charged at the time of preparation × 100.

As can be seen from table 1, the processing decomposition rate of the water-soluble chitosan composite polyurethane-based avermectin microcapsule suspension prepared in examples 1-2 is 0, the thermal storage decomposition rate after storage for 14 days at 54 ℃ ± 2 ℃ is not more than 0.5%, the decomposition rate is not more than 3% and the coating rate is more than 98% after continuous irradiation for 24 hours under an ultraviolet lamp with a dominant wavelength of 254nm and a lamp distance of 15 cm; whereas the conventional microcapsule preparations 1 and 2 had a processing decomposition rate of 1.6% and 2.0%, respectively, a thermal storage decomposition rate of 4.2% and 7.8%, respectively, an ultraviolet decomposition rate of 13.8% and 29.5%, respectively, and a coating rate of 90.4% and 86.57% under the same conditions, and the conventional microcapsule preparation 2 had a particle diameter (D50) of 16.382 μm and a larger particle diameter. The compound polyurethane/polyurea abamectin microcapsule suspension preparation is obviously superior to the conventional microcapsule preparation in the aspects of processing stability and storage stability.

Test example 2

And (3) measuring the indoor biological activity of the abamectin B2 microcapsule.

The abamectin B2 microcapsule suspending agent prepared in the embodiment 1-3, the conventional microcapsule suspending agent 1 and the conventional microcapsule suspending agent 2 are subjected to a tomato root-knot nematode prevention and control test. The conventional microcapsule suspending agent 1 is prepared by taking polyurethane as a wall material, and the conventional microcapsule suspending agent 2 is prepared by taking chitosan as a wall material.

The test method is as follows:

(1) planting: uniformly mixing sandy loam and iridite according to the proportion of 1:1 to prepare nutrient soil, transplanting tomato seedlings into a nutrient clock containing the nutrient soil, and watering regularly (for 5-7 days) under the planting conditions that: humidity is 50%, temperature is 25 ℃, and illumination is carried out for 10 h/d. And inoculating second-instar nematodes when the tomato seedlings grow to 15-20cm in height.

(2) Hatching second-instar nematodes: picking nematode egg blocks from water spinach diseased roots infected with the meloidogyne incognita, placing the nematode egg blocks into a culture box III containing a proper amount of deionized water, incubating for 2-3 days in an incubator at the constant temperature of 25 ℃, collecting a meloidogyne incognita suspension, diluting the suspension into 100 pieces/ml, and storing for later use.

(3) Inoculation and pesticide application: after the tomato seedlings are planted, 57 strong tomato seedlings are selected and inoculated with root knot nematodes, 1000 seedlings are inoculated with each tomato seedling, 6 treatment groups, 1 positive control group and 1 negative control group, the treatment groups are provided with three pesticide application concentrations, each concentration is repeated, and all tested seedlings are numbered, listed and registered. Specific dosing regimens are shown in table 5.

TABLE 5 control of tomato root-knot nematodes

After 50 days of drug application, the tested seedlings are carefully pulled out, washed by clear water, and the number of root knots and egg masses of each plant is counted to evaluate the disease index and the prevention and treatment effect.

Grading standard of tomato root-knot nematode disease grade index: level 0: no root knot exists; level 1: 1-10% of the roots have root knots; and 2, stage: 11% -25% of roots have root knots: and 3, level: 26% -50% of roots have root knots: 4, level: 51% -75% of roots have root knots: and 5, stage: over 76% of the roots had root knots. And calculating the root knot index and the prevention and treatment effect according to the counted disease index.

Root knot index ═ Σ (number of plants of each disease class × number of disease class)/(total number of investigated plants × number of highest disease class) × 100

Control effect (%) - (control root knot index-treatment root knot index)/control root knot index x 100

The test results are shown in table 6.

TABLE 6 Abamectin B2 microcapsule suspension dosage and control effect

As can be seen from table 6, after the avermectin B2 microcapsule suspension prepared in embodiments 1 to 3 of the present invention is applied, the number of root knots and the number of egg masses are significantly reduced compared with those of positive control, the control effect can reach more than 95% after 50 days of application, which is higher than that of the microcapsule prepared by the conventional method, and the control effect of the emulsifiable solution is only about 70%, which indicates that the two preparations of the present invention have good control effect on root-knot nematodes. It can be seen from the root length and the fresh weight of the overground part of the tomato plant that the microcapsule prepared by using the traditional polyurethane as the material has no promotion effect on the growth of the tomato root system, while the avermectin B2 microcapsule suspending agent prepared by compounding the modified chitosan, the modified polyglutamic acid and the modified micromolecule polypeptide as the curing agent and the polyurethane material has obvious promotion effect on the tomato root system and the fresh weight of the overground part of the tomato plant in the embodiments 1-3.

The above examples and experimental examples fully demonstrate that, in the aspect of preventing and treating root-knot nematodes, the microcapsule suspension of the invention has obvious technical advantages compared with the microcapsules 1 and 2 prepared from traditional preparations and traditional materials, the microcapsule suspension has smaller particle size, good controlled release performance, easy movement in soil, easier penetration and absorption in plant root systems, obvious growth promotion effect advantages, simple and convenient preparation method, and easy realization of industrial production.