Polyurea microcapsule indoxacarb red imported fire ant poison bait and preparation method thereof

Abstract

The invention provides a polyurea microcapsule indoxacarb red imported fire ant poison bait and a preparation method thereof. The indoxacarb polyurea microcapsule is prepared by adopting an interfacial polymerization method. The polyurea microcapsule indoxacarb poison bait is used for controlling the solenopsis invicta, the propagation range and the coverage depth of the poison bait in a solenopsis invicta nest are effectively increased through slow release of the indoxacarb, meanwhile, the lasting period of the poison bait is prolonged, and the continuous control effect on the solenopsis invicta is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of plant protection, and particularly relates to a polyurea microcapsule indoxacarb red imported fire ant bait and a preparation method thereof. Background Art

[0002] The red imported fire ant is one of the 100 most destructive alien invasive species in the world. It is not only a urban pest, but also an agricultural and medical pest. The red imported fire ant can damage urban circuits, gnaw on crops, harm orchards, livestock and poultry, etc.; it can even endanger human health. Some people with sensitive constitutions may experience chest pain, difficulty breathing or speaking, paralysis, heart attacks, and even anaphylactic shock due to the venom protein in the venom, and in severe cases, death may occur. Among them, farmers and children are more affected. Farmers are easily bitten by red imported fire ants during labor, and children are easily bitten when playing.

[0003] At present, indoxacarb bait is one of the main chemical means for controlling red imported fire ants. It mainly acts through stomach toxicity and can achieve efficient poisoning after the red imported fire ants feed on the bait, with a quick effect, but there are limitations in actual applications. On the one hand, the release rate of indoxacarb is relatively fast, resulting in too short a poisoning time for worker ants, and the spread range of the bait inside the nest is limited. In particular, the queen ants and young ants in the deep layer of the nest are difficult to be affected by sufficient toxins, and the control effect is not complete. On the other hand, indoxacarb is easily degraded rapidly under the influence of high temperature, humidity and light in the outdoor environment, resulting in a short effective period, and recurrence of red imported fire ants is likely to occur after prevention and control. Therefore, how to regulate the release rate of indoxacarb, extend its effective period, and enhance the spreading ability of the bait in the ant nest is a key problem in the prevention and control of red imported fire ant bait.

[0004] Pesticide microcapsules are one of the important directions for the future development of pesticide formulations. They can not only protect the active ingredients from environmental damage, reduce the dosage and frequency of pesticide use, but also have good slow-release performance. The research and application of pesticide microencapsulation technology in China have just started, and only some microcapsule products such as phoxim, chlorpyrifos and avermectin have been commercialized. The research and development of microcapsule indoxacarb bait can not only extend the continuous prevention and control effect on red imported fire ants, but also provide a case for the research and application of pesticide microencapsulation technology in China.

[0005] The interfacial polymerization method is a commonly used film-making method in the film industry, and its process is simple and can be continuously produced on a large scale.

[0006] The current technology for controlling Solenopsis invicta mainly relies on indoxacarb bait. Although it is effective quickly, due to its too fast release rate, it limits the spread range of the bait in the ant nest and has insufficient control effect on the queen ants and young ants. At the same time, indoxacarb has poor stability in the outdoor environment, and the problem of Solenopsis invicta becoming rampant again easily occurs after prevention and control. The present invention aims to significantly improve its spreadability and environmental stability by using the polyurea microcapsule technology to optimize the slow release of indoxacarb bait, so as to achieve efficient and continuous control of Solenopsis invicta. Summary of the Invention

[0007] The purpose of the present invention is to provide a polyurea microcapsule indoxacarb Solenopsis invicta bait and its preparation method.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions: A preparation method of a polyurea microcapsule indoxacarb Solenopsis invicta bait includes the following steps: (1) Preparation of polyurea microcapsule indoxacarb suspension: Dissolve indoxacarb and MDI (4,4'-diphenylmethane diisocyanate, AR) in cyclohexanone as the oil phase, where the concentrations of indoxacarb and MDI are 5wt% and 1.8wt% respectively; dissolve alkylphenol polyoxyethylene ether OP-10 and sodium lignosulfonate in water as the water phase, where the concentrations of alkylphenol polyoxyethylene ether OP-10 and sodium lignosulfonate are 1.5wt% and 3wt% respectively; after mixing the water phase and the oil phase, homogenize and shear at a certain power at room temperature to obtain an emulsion, and raise the temperature to 70°C under the stirring condition of 300 rpm and react for 3 h to obtain a polyurea microcapsule indoxacarb suspension; (2) Preparation of polyurea microcapsule indoxacarb bait: Dilute the polyurea microcapsule indoxacarb suspension with distilled water and mix it with a commercial bait. After mixing, air-dry it in a fume hood to finally obtain a polyurea microcapsule indoxacarb bait containing 0.04wt% of indoxacarb.

[0009] Preferably, the homogenization condition is homogenizing at 10,000 rpm for 5 minutes, and the particle size of the prepared indoxacarb polyurea microcapsule is 1.72μm.

[0010] Preferably, the mass ratio of the oil phase to the water phase is 0.4:1 - 1.5:1.

[0011] Preferably, the commercial bait mainly plays an inducing role and does not contain chemical insecticides such as indoxacarb. Its main components include defatted corn kernels and vegetable oil.

[0012] The advantages of the present invention are: The difference between this proposal and the prior art lies in the use of indoxacarb bait encapsulated in polyurea microcapsules for the control of Solenopsis invicta. By using the indoxacarb bait encapsulated in polyurea microcapsules, indoxacarb is slowly released, enhancing its spreadability and environmental stability, increasing the spread range of the bait within the ant nest, and prolonging the continuous control effect on Solenopsis invicta.

[0013] The prior art only uses indoxacarb bait to control Solenopsis invicta, and further only conducts control through indoxacarb bait with different concentrations. The indoxacarb bait encapsulated in polyurea microcapsules of the present invention can effectively prolong the duration of Solenopsis invicta control. Brief Description of the Drawings

[0014] Figure 1 Particle size distribution of indoxacarb microcapsules obtained under different homogenization conditions; Figure 2 Scanning electron microscope images of indoxacarb microcapsules obtained under different homogenization conditions. Detailed Description of the Invention

[0015] To make the above features and advantages of the present invention more obvious and understandable, specific embodiments are given below for detailed description. Unless otherwise specified, the methods of the present invention are conventional methods in the art.

[0016] Example 1 A method for preparing indoxacarb bait for Solenopsis invicta encapsulated in polyurea microcapsules, comprising the following steps: (1) Preparation of indoxacarb polyurea microcapsule suspension: Interface polymerization is used to prepare indoxacarb polyurea microcapsules. Indoxacarb and MDI (4,4'-diphenylmethane diisocyanate, AR) are dissolved in cyclohexanone as the oil phase, where the concentrations of indoxacarb and MDI are 5 wt% and 1.8 wt% respectively; alkylphenol polyoxyethylene ether OP-10 and sodium lignosulfonate are dissolved in water as the water phase, where the concentrations of alkylphenol polyoxyethylene ether OP-10 and sodium lignosulfonate are 1.5 wt% and 3 wt% respectively; after mixing the water phase and the oil phase at a mass ratio of 1:1, a emulsion is obtained by homogenizing and shearing at a certain power at room temperature, and then transferred to a three-necked flask. The temperature is raised to 70 °C under stirring at 300 rpm and reacted for 3 h. To prepare four indoxacarb microcapsules with increasing particle sizes, the homogenization conditions are 10,000 rpm for 5 minutes, 10,000 rpm for 3 minutes, 5,000 rpm for 5 minutes, and 5,000 rpm for 3 minutes respectively.

[0017] (2) Preparation of indoxacarb bait encapsulated in polyurea microcapsules: The indoxacarb polyurea microcapsule suspension is diluted with distilled water and mixed with a commercially available bait carrier (provided by Ruifeng Company), and then air-dried in a fume hood. Finally, indoxacarb bait encapsulated in polyurea microcapsules containing 0.04 wt% of indoxacarb is obtained.

[0018] Further, the indoxacarb was obtained from Nantong Shizhuang Chemical Co., Ltd., MDI (4,4'-diphenylmethane diisocyanate, AR) was purchased from Wanhua Shandong Chemical Industry Group Co., Ltd., cyclohexanone was purchased from Kermel Chemical Reagent Co., Ltd. (Tianjin, China), OP-10 was purchased from Zibo Yunchuan Chemical Co., Ltd. (Shandong, China), and sodium lignosulfonate (sulfonation degree 0.8 mol / kg, average molecular weight 10,000 Da) was provided by MeadWestvaco Corp. (Illinois, USA). The commercially available bait carrier has the same composition and content as the commercially available indoxacarb bait carrier, except that it does not contain indoxacarb.

[0019] Further, the indoor test was located at the Jinshan Campus of Fujian Agriculture and Forestry University, Jianxin Town, Cangshan District, Fuzhou City (26.08°N, 119.24°E), and the test field was located at the Qishan Campus of Fujian Agriculture and Forestry University, University Town, Minhou County, Fuzhou City (26.06°N, 119.18°E).

[0020] Further, after mixing, it was ventilated in a fume hood until the bait was dry.

[0021] Further, in the indoor test, 1 g of bait was placed in each artificial ant nest, and the number of dead worker ants was counted every day; in the field test, 20 g of bait was used for each nest of red imported fire ants.

[0022] Further, after spreading the bait in summer, a trapping experiment was carried out with ham sausage for 3 consecutive days, then once every 7 days, and the test was carried out for 21 days. After the initial application in autumn, according to the control effect of the medicament, it was applied once every 7 days. After each application of the bait, a trapping experiment was carried out with ham sausage for 3 consecutive days, then once every 7 days, and it was applied 3 times in total. The third application was observed for 21 days, and a total of 42 days were carried out.

[0023] Further, the spreading method was circular spreading, that is, the bait was spread in a circle around the red imported fire ant nest. The medicament control was a 0.1 wt% commercially available indoxacarb bait.

[0024] As Figure 1 shown, four different particle size MCs samples with average diameters of 1.72 μm (Microcapsules-A, MCs-A), 2.40 μm (MCs-B), 5.46 μm (MCs-C), and 10.02 μm (MC-D) were obtained by controlling the preparation process. Their morphologies were observed by optical microscopy (and scanning electron microscopy). The morphology of the prepared indoxacarb microcapsule suspension was irregular, the capsule shell was concave inward, the surface was relatively smooth, and with the increase of the particle size, the morphology did not change significantly (as Figure 2 shown). The encapsulation rates of the four different particle size indoxacarb microcapsules were all between 91-95%.

[0025] Indoor test results of Solenopsis invicta Buren bait Mortality rate of worker ants Corrected mortality rate The control group was a blank control.

[0026] Table 1 Indoor toxicity test of indoxacarb bait encapsulated in polyurea microcapsules The results of the indoor toxicity test are shown in Table 1. Four days after the application, the corrected mortality rate of worker ants in the artificial ant nest of the chemical control group (0.1 wt% indoxacarb) reached 100%. The corrected mortality rate of Group A reached 100% on the 10th day. The mortality rates of Groups B, C, and D were relatively low, and the mortality rate of Group D still did not exceed 10% on the 10th day. Therefore, particle size D was not used for field trials in the follow-up.

[0027] Field test results of Solenopsis invicta Buren bait Control effect on worker ants According to the investigation results of the trapping method, the control effect on worker ants was calculated according to the following formula: In the formula: Pw is the control effect on worker ants; W0 is the average number of worker ants in the monitoring bottle in the control area before treatment; W T1 is the average number of worker ants in the monitoring bottle in the treated area after treatment; W1 is the average number of worker ants in the monitoring bottle in the control area after treatment; W T0 is the average number of worker ants in the monitoring bottle in the treated area before treatment.

[0028] Table 2 Control effect of indoxacarb bait encapsulated in polyurea microcapsules (summer) on worker ants The control results on worker ants in summer are shown in Table 2. Fourteen days after the application, the control effect of the chemical control began to decline. Twenty-one days after the application, the control efficiency of the chemical control was lower than 50%. However, the control effects of Treatments A and B were still at a relatively high level, indicating that the persistence of Treatments A and B was higher than that of the chemical control. Generally speaking, the effect of Treatment A was the most ideal. In the indoor test, the worker ants in Treatment A had twitching feet but could still move normally 1 - 3 days after treatment. It may be due to this effect that no worker ants could be trapped on the first day of the field test and there was no activity of worker ants in the ant nest, making Treatment A effective quickly. The control effect of Treatment B was relatively slow, and its persistence was also higher than that of the chemical control. In Treatment C, the microcapsule particle size was the largest and the slow-release time was the longest. Therefore, the control effect was still not ideal 21 days later. In summary, among the three indoxacarb baits encapsulated in polyurea microcapsules, the control effect of Treatment A was the most ideal.

[0029] Table 3 Control effect of indoxacarb bait encapsulated in polyurea microcapsules (autumn) on worker ants The control results of worker ants in autumn are shown in Table 3. The continuous control effect of the chemical control group lasted for 7 days. Except that the control efficiency of the control chemical remained above 90% on the 7th day when it was first applied, the control effects of the other applications were relatively low on the 7th day. However, the control effect of Treatment A remained above 95% during the experiment. No worker ants were trapped on the 7th day of the first application and two days before the second application in Treatment B, but there were still many less active red imported fire ants in the ant nest, and the subsequent control effect continued to decline. The control effect of Treatment C was unstable. In summary, among the three kinds of polyurea microcapsule indoxacarb baits, the control effect of Treatment A was the most ideal, that is, the optimal particle size was 1.72 μm.

[0030] Based on the above experiments, the indoxacarb bait with particle size A has both slow-release effect and good control effect, and can continuously control red imported fire ants.

[0031] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A preparation method of a polyurea microcapsule indoxacarb red imported fire ant bait, characterized in that, It includes the following steps: (1) Preparation of indoxacarb suspension in polyurea microcapsules: Dissolve indoxacarb and MDI in cyclohexanone as the oil phase; dissolve alkylphenol polyoxyethylene ether OP-10 and sodium lignosulfonate in water as the water phase; after mixing the water phase and the oil phase, homogenize and shear at a certain power at room temperature to obtain an emulsion, heat it to 70 °C under stirring at 300 rpm and react for 3 h to obtain indoxacarb suspension in polyurea microcapsules; (2) Preparation of indoxacarb bait in polyurea microcapsules: Dilute the indoxacarb suspension in polyurea microcapsules with distilled water and mix it with the commercial bait, and air-dry it in a fume hood, finally obtaining indoxacarb bait in polyurea microcapsules containing 0.04 wt% of indoxacarb.

2. The preparation method according to claim 1, characterized in that, The concentrations of indoxacarb and MDI in the oil phase are 5 wt% and 1.8 wt% respectively.

3. The preparation method according to claim 1, characterized in that, The concentrations of alkylphenol polyoxyethylene ether OP-10 and sodium lignosulfonate in the water phase are 1.5 wt% and 3 wt% respectively.

4. The preparation method according to claim 1, characterized in that, The homogenization condition is homogenizing at 10,000 rpm for 5 minutes.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the oil phase to the water phase is 0.4:1 - 1.5:

1.

6. The indoxacarb fire ant bait in the form of polyurea microcapsules prepared by the preparation method according to any one of claims 1-5, characterized in that, The particle size of indoxacarb polyurea microcapsules is 1.72 μm.

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