Preparation method and application of weevil pest repellent

Abstract

The invention belongs to the technical field of forestry pest control, and discloses a preparation method and application of a weevils pest repellent. The raw materials comprise trans-2-hexenal and reduced glutathione; the molar ratio of the trans-2-hexenal to the reduced glutathione is 1: (3.5 to 4.0). According to the invention, trans-2-hexenal and reduced glutathione are subjected to a Michael addition reaction so as to prepare the slow-release trans-2-hexenal repellent. The repellent provided by the invention has a slow release effect, the release amount of trans-2-hexenal is increased along with the increase of temperature and humidity, the release amount reaches 80% within 7 days, and the cost is saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of forestry pest control, and relates to a preparation method and application of a repellent for weevil pests. Background Art

[0002] The family Curculionidae belongs to Coleoptera, which is the largest family in the animal kingdom, with a very large number of species and a wide distribution. Currently, 50,000 species are known worldwide, and more than 1,200 species are recorded in China. Many species are important pests in agriculture and forestry, such as Sitophilus zeamais, Acanthoscelides obtectus, and Echinocnemus squameus, causing serious economic losses. Due to the boring damage characteristics of Curculionidae pests, the effect of conventional spraying of chemical agents for control is poor. In recent years, repellents, attractants or insecticides developed based on insect semiochemicals have become one of the key green pest control technologies. Insect semiochemicals include volatiles of host or non-host plants and pheromones released by the insect body itself. Semiochemicals have unique advantages in controlling Curculionidae pests, but the process of practical popularization and commercial development is very slow, due to difficulties in artificial synthesis technology, poor slow-release properties, etc. Therefore, developing an information-based substance preparation technology for efficient and green control of weevil pests is a problem that needs to be solved urgently.

[0003] Trans-2-Hexenal is a small molecule aldehyde with a six-carbon main chain. As a volatile organic compound (VOCs), it widely exists in plants. It is an important plant chemical defense factor with various biological activities, including antibacterial and inducing plant defense responses. When plants are damaged by pests, VOCs play a key role in the communication of defense information between plants. Research shows that trans-2-hexenal, as a natural volatile, has significant antibacterial properties and can inhibit the biological activities of Gram-negative, Gram-positive bacteria and some fungi at relatively low concentrations. Another study shows that trans-2-hexenal, as a defense substance against insect feeding, affects the behaviors of phytophagous insects such as feeding, mating and oviposition. When phytophagous insects feed on plants, volatile substances not only transmit signals within the plant itself, causing the expression of defense pathway genes such as JA (jasmonic acid) and SA (salicylic acid) in the body, but also can act as a "messenger" between plants, attracting the natural enemies of pests or transmitting signals to help other plants indirectly resist insect attacks. Exogenous application of trans-2-hexenal can effectively control pests. Due to the advantages of trans-2-hexenal such as safety, high efficiency and low residue, it has broad application prospects in agriculture. By exogenous application of trans-2-hexenal, plants can be effectively induced to produce disease resistance, reduce the use of chemical pesticides and protect the ecological environment.

[0004] However, the boiling point of trans - 2 - hexenal is 47°C, and it is extremely volatile in the natural environment. It is very difficult for existing spraying technologies to enable it to play a long - term and stable defensive role. Currently, the method of biosynthesizing trans - 2 - hexenal based on Michael addition reaction has achieved obvious effects in the prevention and control of strawberry gray mold. Compared with other chemical methods, the Michael addition reaction has the advantages of not requiring the addition of any chemical catalysts or initiators harmful to cells, mild reaction conditions, and a very fast reaction rate without bringing other by - products. However, there is currently no relevant report on the application of synthesizing trans - 2 - hexenal by this method in the prevention and control of weevil pests. In particular, whether trans - 2 - hexenal has an obvious repellent effect on weevil pests, whether the repellent effect can last, and whether a repellent control product suitable for the living environment of weevil pests can be developed, etc. To sum up, the development of a slow - release trans - 2 - hexenal repellent has great application value in the prevention and control of weevil pests. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a preparation method and application of a weevil pest repellent. The repellent provided by the present invention has a slow - release effect. The release amount of trans - 2 - hexenal increases with the increase of temperature and humidity, and the release amount reaches 80% within 7 days, saving costs.

[0006] The above - mentioned object of the present invention is achieved by the following technical solutions:

[0007] A weevil pest repellent, the raw materials include trans - 2 - hexenal and reduced glutathione; the molar ratio of trans - 2 - hexenal to reduced glutathione is 1:3.5 - 4.0.

[0008] The present invention also claims the preparation method of the above - mentioned weevil pest repellent, which uses trans - 2 - hexenal and reduced glutathione to carry out Michael addition reaction to prepare a slow - release trans - 2 - hexenal repellent.

[0009] The preparation method of the above - mentioned weevil pest repellent is as follows:

[0010] S1. Dissolve reduced glutathione in 0.05% dimethyl sulfoxide solution to obtain a mixed solution;

[0011] S2. Add trans - 2 - hexenal to the mixed solution prepared in step S1 and stir evenly to obtain a product;

[0012] S3. Perform vacuum freeze - drying treatment on the product obtained in step S2; the obtained powder is a slow - release trans - 2 - hexenal repellent.

[0013] Further, in step S2, the molar ratio of reduced glutathione to trans - 2 - hexenal is 3.775:1.

[0014] Furthermore, in step S2, the stirring conditions are as follows: the stirring temperature is 25 - 30 °C, and the stirring time is 30 - 60 min.

[0015] Furthermore, in step S3, the vacuum freeze-drying conditions are as follows: the vacuum freezing time is 24 - 48 h, the cold trap temperature is below -45 °C, and the vacuum degree is below 0.15 mBar.

[0016] The present invention also claims the application of the weevil pest repellent prepared by the above preparation method in preventing and controlling typical weevil pests.

[0017] The application is specifically as follows: the prepared powdery slow-release trans-2-hexenal repellent is filled into a special paper bag for desiccant; the special paper bag for desiccant is placed into a plastic bait cage; the plastic bait cage is tied and hung on a tree branch. The slow-release trans-2-hexenal repellent has a repellent effect and a slow-release effect within 7 days at 20 - 40 °C (the temperature range during the peak damage period of weevil pests).

[0018] Typical weevil pests include Sitophilus zeamais and Acanthoscelides obtectus.

[0019] Reduced glutathione has good thiol reactivity and can quickly undergo an addition reaction with trans-2-hexenal molecules to prepare a trans-2-hexenal slow-release precursor compound. This reaction is affected by temperature and humidity and has the characteristics of temperature and humidity response. Glutathione can participate in biotransformation, convert harmful poisons in the body into harmless substances, excrete them out of the body, and also help maintain the normal function of the immune system. It can be used as a base material for functional foods, has good food safety, and is environmentally friendly. The present invention selects reduced glutathione to react with trans-2-hexenal to prepare a slow-release trans-2-hexenal repellent. The prepared slow-release trans-2-hexenal repellent has a good repellent effect on typical weevil pests.

[0020] The beneficial effects of the present invention compared with the prior art are as follows:

[0021] 1) The present invention uses an addition reaction to synthesize a stable product from the volatile substance trans-2-hexenal and reduced glutathione, overcomes the application drawback of its extremely easy volatility, and realizes its long-term and stable function of repelling weevil pests;

[0022] 2) The repellent provided by the present invention has a slow-release effect, and the release amount of trans-2-hexenal increases with the increase of temperature and humidity, and the release amount reaches 80% within 7 days, saving costs;

[0023] 3) The preparation and packaging methods of the repellent are simple to operate and convenient for realizing slow release;

[0024] 4) The trans-2-hexenal and reduced glutathione used in the present invention are safe and reliable and environmentally friendly;

[0025] 5) The repellent prepared by the present invention has an obvious repellent effect on typical weevil pests (Sitophilus zeamais and Sitophilus oryzae). Description of the Drawings

[0026] Figure 1 It is a diagram of the product of the addition reaction between reduced glutathione and trans-2-hexenal molecules in Example 1 of the present invention.

[0027] Figure 2 It is the ion chromatogram (XIC) of the addition product of reduced glutathione and trans-2-hexenal in Example 1 of the present invention.

[0028] Figure 3 It is a diagram of the repellent effect of the trans-2-hexenal repellent prepared in Example 1 of the present invention on two kinds of weevils. In the figure: a is Sitophilus zeamais, and b is Sitophilus oryzae.

[0029] Figure 4 It is a diagram of the results of the release amount of the trans-2-hexenal repellent of the present invention varying with temperature and relative humidity. In the figure: a is under the condition of 20 °C, b is under the condition of 30 °C, and c is under the condition of 40 °C.

[0030] Figure 5 It is a schematic diagram of the application state preparation of the sustained-release trans-2-hexenal repellent prepared in Example 1. Detailed Embodiments

[0031] The present invention will be described in detail below through specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained from commercial channels.

[0032] Example 1

[0033] Dissolve 2 g of reduced glutathione in 12 mL of 0.05% dimethyl sulfoxide solution. After complete dissolution, add 0.2 g of trans-2-hexenal, stir evenly with a magnetic stirrer, the stirring temperature is 25 °C, the stirring time is 45 min, freeze-dry the obtained product under vacuum, the cold trap temperature is -45 °C, the vacuum degree is 0.15 mBar, and freeze-dry for 24 h. A sustained-release trans-2-hexenal repellent is obtained. As Figure 1 shown, the trans-2-hexenal repellent is in the form of white powder. From Figure 2 it can be seen that the response intensity is relatively strong at 3.5 - 4.0 min, and it can be judged that the purity of the addition product trans-2-hexenal repellent is relatively high. Figure 3The repellent effect of the trans-2-hexenal repellent on two species of weevils (a. Sitophilus zeamais, b. Acanthoscelides obtectus). In the figure, the addition product and food were placed in the center of the petri dish, and only food was placed at the edge. Both species of weevils moved or fed around the edge of the petri dish, avoiding the central part, indicating that the addition product has a repellent effect on weevils.

[0034] Slow-release research example 1

[0035] Add 10 g of silica gel that changes color, 10 mL of saturated magnesium chloride solution, 10 mL of magnesium nitrate solution, 10 mL of saturated sodium chloride solution, 10 mL of saturated potassium chloride solution, and 10 mL of pure water to 50 mL centrifuge tubes respectively, seal them, and the internal relative humidity is 0%, 30%, 50%, 75%, 85%, 100% respectively. Place them at 20 °C and equilibrate for 2 h.

[0036] Weigh 0.1 g of the slow-release trans-2-hexenal repellent prepared in Example 1 into a 2 mL centrifuge tube, transfer it to the above 50 mL centrifuge tube, seal it, and place it in a 20 °C constant temperature incubator for 7 d. Measure the release amount once a day.

[0037] Slow-release research example 2

[0038] Add 10 g of silica gel that changes color, 10 mL of saturated magnesium chloride solution, 10 mL of magnesium nitrate solution, 10 mL of saturated sodium chloride solution, 10 mL of saturated potassium chloride solution, and 10 mL of pure water to 50 mL centrifuge tubes respectively, seal them, and the internal relative humidity is 0%, 30%, 50%, 75%, 85%, 100% respectively. Place them at 30 °C and equilibrate for 2 h.

[0039] Weigh 0.1 g of the slow-release trans-2-hexenal repellent prepared in Example 1 into a 2 mL centrifuge tube, transfer it to a 50 mL centrifuge tube, seal it, and place it in a 30 °C constant temperature incubator for 7 d. Measure the release amount once a day.

[0040] Slow-release research example 3

[0041] Add 10 g of silica gel that changes color, 10 mL of saturated magnesium chloride solution, 10 mL of magnesium nitrate solution, 10 mL of saturated sodium chloride solution, 10 mL of saturated potassium chloride solution, and 10 mL of pure water to 50 mL centrifuge tubes respectively, seal them, and the internal relative humidity is 0%, 30%, 50%, 75%, 85%, 100% respectively. Place them at 40 °C and equilibrate for 2 h.

[0042] Weigh 0.1 g of the slow-release trans-2-hexenal repellent prepared in Example 1 into a 2 mL centrifuge tube, transfer it to a 50 mL centrifuge tube, seal it, and place it in a 40 °C constant temperature incubator for 7 d. Measure the release amount once a day.

[0043] Figure 4It reflects the results of the release amount of trans-2-hexenal in the product varying with temperature (a. 20 °C; b. 30 °C; c. 40 °C) and relative humidity (0%, 30%, 50%, 75%, 85%, 100%). It can be seen that as the relative humidity increases, the release rate of trans-2-hexenal in the product increases; as the temperature increases, the release rate of trans-2-hexenal in the product also increases. This result indicates that the obtained addition product has the characteristic of slow-release of trans-2-hexenal, and the release amount has a positive correlation with the changes in temperature and humidity.

[0044] Application Example 1

[0045] The slow-release trans-2-hexenal repellent prepared in Example 1 was packaged in a special paper bag for desiccants and then placed in a plastic bait cage. After tying the rope, it can be hung on a tree branch for application.

[0046] The above results show that the addition product of reduced glutathione and trans-2-hexenal prepared in the present invention can be successfully prepared. This addition product has a repellent effect on typical weevil pests, and it has slow-release kinetic characteristics. The release amount increases with the changes in environmental temperature and humidity, and it can play a role in repelling weevil pests stably for a long time.

[0047] The slow-release effect of the repellent prepared in the present invention, which varies with environmental temperature and humidity, has good practical applicability in the field of controlling weevil pests and other fields.

[0048] The above-described embodiments are only the preferred embodiments of the present invention, and not all the feasible embodiments of the present invention. For those of ordinary skill in the art, any obvious modifications made without departing from the principle and spirit of the present invention should be considered to be included within the protection scope of the claims of the present invention.

Claims

1. A weevil pest repellent, characterized in that: The raw materials include trans-2-hexenal and reduced glutathione; the molar ratio of trans-2-hexenal to reduced glutathione is 1:3.5-4.

0.

2. The method for preparing the weevil pest repellent as claimed in claim 1, characterized in that: The sustained-release trans-2-hexenal repellent was prepared by Michael addition reaction of trans-2-hexenal and reduced glutathione.

3. The method for preparing the weevil pest repellent as claimed in claim 2, characterized in that: The specific steps are as follows: S1. dissolving reduced glutathione in 0.05% dimethyl sulfoxide solution to prepare a mixed solution; S2. Add trans-2-hexenal to the mixed solution obtained in step S1 and stir evenly to obtain a product; S3. The product obtained in step S2 is subjected to vacuum freeze-drying treatment; the obtained powder is a sustained-release trans-2-hexenal repellent.

4. The method for preparing the weevil pest repellent as claimed in claim 3, characterized in that: In step S2, the stirring conditions are: stirring temperature is 25-30°C, and stirring time is 30-60min.

5. The method for preparing the weevil pest repellent as claimed in claim 3, characterized in that: In step S3, the vacuum freeze-drying conditions are: vacuum freezing time is 24-48 hours, cold trap temperature is lower than -45°C, and vacuum degree is lower than 0.15 mBar.

6. Use of the weevil pest repellent prepared by the preparation method of the weevil pest repellent according to any one of claims 2 to 5 in preventing and controlling typical weevils.

7. The use according to claim 6, characterized in that: The prepared powdered sustained-release trans-2-hexenal repellent is put into a paper bag for desiccant; the paper bag for desiccant is put into a plastic bait net cage; and the plastic bait net cage is hung on a tree branch with a tie.

8. The use according to claim 6, characterized in that: Weevil pests include corn weevils and soybean weevils.

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