Application of oregano essential oil in prevention and treatment of fruit flies

Abstract

The application discloses application of oregano essential oil in prevention and treatment of real flies. The application first discovers the repellent effect of oregano essential oil on real flies. After oregano essential oil or a preparation prepared by taking oregano essential oil as an effective component is sprayed on the surface of fruits, the egg-laying amount of the fruits is significantly reduced, thereby the egg-laying effect of Bactrocera dorsalis is inhibited, and the repellent effect is enhanced with the increase of the concentration. When the concentration is 100 μL / mL, the repellent rate of the oregano essential oil on female Bactrocera dorsalis reaches about 70%, the egg-laying repellent rate reaches 100.00%, and the oregano essential oil plays a significant protection role on the fruits. The oregano essential oil is non-toxic and harmless to the environment, has significant benefits, and has a broad development prospect. Therefore, the oregano essential oil can be used as or prepared into a repellent of Bactrocera dorsalis or even real fly pests, thereby being used in prevention and treatment of real flies.

Description

Technical Field

[0001] This invention relates to the fields of plant protection and pesticide research and development, and more specifically, to the application of oregano essential oil as a repellent in the control of fruit flies. Background Technology

[0002] Fruit flies are the common name for insects belonging to the family Tetriphitidae in the order Diptera. Fruit fly pests are characterized by their wide diet, significant generational overlap, and high reproductive rate. Female adults can lay several eggs at a time, and their development period is relatively short. Once they migrate into host plant areas, the fruit fly population increases rapidly in a short period, making control extremely difficult. Among them, the citrus fruit fly (Bactrocera dorsalis) can damage the fruits of various fruit trees (citrus, mango, banana, plum, peach, pomegranate, star fruit, jujube, pear, apple, etc.) and vegetables (pumpkin, eggplant, pepper, cucumber, tomato, etc.), and is listed as a globally important quarantine pest. In 1992, my country included it in the list of Class II dangerous pests for imported plants. Currently, the main method for controlling the oriental fruit fly is chemical control. However, due to the fly's characteristics—the female adult inserts her ovipositor into the fruit to lay eggs, and the larvae, after hatching, bore into the fruit, causing internal rot—the adult flies detach from the fruit and pupate in the soil. Therefore, chemical agents that can only be sprayed on the surface are ineffective, and the fly easily develops resistance to most insecticides, resulting in unsatisfactory control effects from chemical methods. Therefore, there is an urgent need to explore other green and efficient innovative control technologies.

[0003] Plant essential oils are volatile oily substances extracted from plants and are natural products. Their application in pest control can effectively address the problem of pesticide resistance in pests, and while releasing the pesticide's properties, it also avoids the environmental problems caused by pesticide accumulation. However, in existing technologies, reports on plant essential oils for fruit fly control mostly involve preparing insecticides from traditional Chinese medicine compositions containing one or more active plant essential oil components to disinfect fruit flies, thus achieving a control effect (e.g., Chinese Patent CN108719345A), or utilizing the attractiveness of some plant essential oils to fruit flies to trap them (e.g., Chinese Patent CN115363030A). Research reports on the repellent effect of plant essential oils on fruit flies are relatively rare.

[0004] Oregano essential oil is a plant essential oil obtained by distilling the vapor from fresh oregano leaves. It possesses multiple functions, including insecticidal and antibacterial properties, and is a pure traditional Chinese medicine additive with broad-spectrum antibacterial effects. Furthermore, oregano essential oil is a highly active, effective, and pollution-free natural product, currently widely used in the preparation of sterilizing agents. To date, there are no reports of using oregano essential oil for fruit fly control, nor are there any reports of using it as a repellent for fruit fly control. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned defects and shortcomings in the prior art and to provide the application of oregano essential oil in the control of fruit flies.

[0006] A second object of the present invention is to provide oregano essential oil as a fruit fly repellent and / or its use in the preparation of fruit fly repellents.

[0007] A third objective of this invention is to provide an oregano essential oil fly repellent.

[0008] A fourth object of the present invention is to provide the application of the oregano essential oil fruit fly repellent in the control of fruit flies.

[0009] The above-mentioned objective of this invention is achieved through the following technical solution:

[0010] Through years of research on plant-derived pesticides, the inventors discovered that plant essential oils possess a wide variety of biological activities. Further research into green control technology for fruit fly pests revealed that oregano essential oil, from dozens of essential oils, has a repellent effect on adult fruit flies, especially females, and can also inhibit oviposition. This is the opposite of traditional control techniques that primarily rely on attractant strategies, and thus proves to be more effective in controlling fruit fly pests.

[0011] Therefore, this invention investigates the repellent effect of oregano essential oil on adult female fruit flies. A selective experiment was conducted using Y-shaped tubes. One tube arm was treated with oregano essential oil and bait, while the other arm served as a control with an equal amount of organic solvent and bait. After introducing adult female fruit flies into the tubes, it was found that the fruit flies almost never entered the oregano essential oil-treated arm, with most crawling into the control arm. Therefore, it was found that oregano essential oil has a significant repellent effect on adult female fruit flies.

[0012] This invention further utilizes the fruit spraying method to determine the oviposition repellency effect of oregano essential oil on oriental fruit fly under non-selective and selective conditions. The oviposition rate of the fruit after spraying was significantly reduced, inhibiting the oviposition of oriental fruit fly, and the repellency effect was obvious.

[0013] This invention is the first to discover that oregano essential oil has a repellent effect on the oriental fruit fly and an oviposition repellent effect. Therefore, oregano essential oil can be used as a repellent for or in the preparation of oriental fruit flies and other fruit fly pests.

[0014] Based on this, the present invention provides the following applications of oregano essential oil:

[0015] Application of oregano essential oil in the control of fruit flies.

[0016] The use of oregano essential oil as a fruit fly repellent and / or in the preparation of fruit fly repellents.

[0017] Furthermore, the fruit flies include, but are not limited to, the oriental fruit fly, and the fruit fly repellent is an adult repellent and an oviposition repellent.

[0018] The present invention also provides a fruit fly repellent containing an oregano essential oil solution at a concentration of 1.25–200 μL / mL. The oregano essential oil can be used as the sole active ingredient in the fruit fly repellent, or it can be combined with other repellent active ingredients to prepare a mixture. Further, the concentration of the oregano essential oil solution is 5–100 μL / mL.

[0019] Preferably, the fruit fly repellent contains an oregano essential oil solution at a concentration of 100 μL / mL.

[0020] Furthermore, the solvent of the oregano essential oil solution is any one or more of acetone, methanol, dimethyl sulfoxide, N,N-dimethylamide, vegetable oil, mineral oil, n-hexane, ethanol, ethyl acetate, and tetrahydrofuran.

[0021] Furthermore, the solvent for the oregano essential oil solution is acetone.

[0022] Furthermore, the dosage forms of the fruit fly repellent include, but are not limited to, any one of the following dosage forms: soluble concentrate, emulsifiable concentrate, wettable powder, water-dispersible granules, soluble granules, microemulsion, water-in-oil emulsion, effervescent tablets, suspension concentrate, or granules.

[0023] Furthermore, the formulation of the fruit fly repellent also includes excipients commonly used in pesticide formulations.

[0024] Furthermore, the excipients include, but are not limited to, any one or more of wetting and dispersing agents, thickeners, stabilizers, thixotropic agents, penetration enhancers, defoamers, antifreeze agents, pH adjusters, and emulsifiers.

[0025] Further, the wetting and dispersing agent is one or more of the following: sodium lignosulfonate, calcium lignosulfonate, sodium lauryl polyoxyethylene ether sulfate, alkyl naphthaldehyde condensate sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, potassium (sodium) oleate, alkyl polyoxyethylene ether sulfonate, alkylphenol polyoxyethylene ether formaldehyde condensate, alkylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, polyoxyethylene polyoxypropylene ether block copolymer, separating powder, sodium polyoxyethylene ester, dodecyl polyoxyethylene ether phosphate, alkyl naphthaldehyde condensate sulfonate, sodium methyl oleate aminoethyl sulfonate, alkyl acid polyoxyethylene ether sulfonate, starch, gelatin, hydroxymethyl cellulose, and polyvinyl alcohol.

[0026] Further, the thickener is one or more of the following: xanthan gum, heteropolysaccharide, hydroxymethyl (ethyl) cellulose, methyl cellulose, gum arabic, guar gum, sodium alginate, carrageenan, pectin, polyvinyl alcohol, bentonite, synthetic hydrated silica, gypsum, acrylic polymers, and magnesium aluminum silicate.

[0027] Further, the stabilizer is one or more of the following: pyrogallol, butyl glycidyl ether, phenyl glycidyl ether, tolyl glycidyl ether, polyvinyl glycol diglycidyl ether, epichlorohydrin, sodium sorbate, sodium benzoate, epoxidized soybean oil, linseed oil, hydroquinone, anthraquinone, eugenol, BHA, BHT, VB, citric acid, ascorbic acid, PABA, hydroxybenzoate, propylparaben, pyrogallol, dihydroxybenzoic acid, FB-28, castor oil, olive oil, hydroquinone, dinaphthol, 1-naphthol, salicylic acid, rosemary oil, benzoic acid, and soluble starch.

[0028] Furthermore, the penetration enhancer is laurocapram or JFC.

[0029] Furthermore, the defoamer is any one of silicone oil, silicone compounds, C10-20 saturated fatty acids, C8-10 fatty alcohols, and 2-ethylhexanol.

[0030] Further, the antifreeze agent is one or more of ethylene glycol, glycerol, propylene glycol, polyethylene glycol, sorbitol, and urea.

[0031] Furthermore, the pH adjuster is any one of sodium hydroxide, ammonia, acetic acid, hydrochloric acid, citric acid, and phosphoric acid.

[0032] Furthermore, the emulsifier is any one or more of Tween-80, Span 80, calcium dodecylbenzenesulfonate, polyoxyethylene sorbitan oleate, and tea saponin.

[0033] Furthermore, the fruit fly repellent is a soluble agent, the components of which include: 20 mL of oregano essential oil, 15 mL of acetone, 0.5 mL of Tween-80, 15 mL of ethanol, and the remaining components are distilled water, totaling 100 mL.

[0034] The present invention also provides the use of oregano essential oil as a fruit fly repellent or any of the above-described fruit fly repellents in the control of fruit flies.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] This invention provides the application of oregano essential oil in the control of fruit flies. This invention is the first study to demonstrate that oregano essential oil has both repellent and oviposition-repellent effects on adult female fruit flies. The oviposition rate of treated fruits is significantly reduced, thereby inhibiting the oviposition of fruit flies. Furthermore, the repellent effect increases with increasing concentration. At a concentration of 100 μL / mL, the repellency rate against adult female fruit flies can reach over 70%, and the oviposition-repellent rate reaches 100.00%, providing significant protection for the fruit. Therefore, oregano essential oil can be used as or prepared as a repellent for fruit flies and other fruit fly pests for the control of fruit flies. Attached Figure Description

[0037] Figure 1 This is a Y-shaped tube measuring device.

[0038] Figure 2 This represents the selection response of female oriental fruit flies to oregano essential oil. Note: * in the figure indicates that the data are statistically significant after t-test (0.01 < P < 0.05), and ** indicates that the data are extremely significant (P < 0.01). Detailed Implementation

[0039] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0040] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0041] The oregano essential oil used in the following examples was purchased from Jiangxi Jinyuan Natural Fragrance Co., Ltd., and the acetone was purchased from Guangzhou Chemical Reagent Factory.

[0042] Example 1: Repellent effect of oregano essential oil on adult female fruit flies

[0043] Oregano essential oil was diluted with acetone to prepare 0.625% (6.25 μL / mL), 1.25% (12.5 μL / mL), 2.5% (25 μL / mL), 5% (50 μL / mL), 10% (100 μL / mL), and 20% (200 μL / mL) oregano essential oil solutions as test samples.

[0044] The repellent effect of essential oils on adult female oriental fruit flies was determined using a Y-type olfactory instrument (e.g., Figure 1 (As shown). One arm of the Y-shaped tube was treated with different concentrations of oregano essential oil, while the other arm served as a blank control. Figure 1Adult fruit flies were inserted into the right end of the Y-shaped tube. The tube was covered to eliminate light source interference. Sexually mature female adults of the same instar were selected as test insects. A selection was considered made if the insect crawled past 2 / 3 of the scent source arm of the Y-shaped tube and remained there for more than 5 seconds; failure to make a selection within 10 minutes was considered rejection. 50 insects were used as a group, and the experiment was repeated 3 times. After every two experiments, the positions of the two arms of the olfactory instrument were reversed, and a new scent source was used to eliminate the influence of geometric factors. After each group of experiments, the inside of the instrument was cleaned with 95% ethanol and dried in an oven at 250℃. After treatment, the number of test insects in the two arms was counted. The results are as follows: Figure 2 As shown, the avoidance rate is calculated using the following formula.

[0045] Repellency rate (%) = (Total number of worms in the control arm - Total number of worms in the treatment arm) / (Total number of worms in the control arm + Total number of worms in the treatment arm) × 100%

[0046] from Figure 2 It can be seen that the number of fruit flies appearing in the tubes treated with different concentrations of oregano essential oil was significantly lower than that in the control tubes, indicating that oregano essential oil has a repellent effect on adult female fruit flies. Calculations based on the above formula show that 10% oregano essential oil achieved a repellency rate of over 70% against adult female fruit flies. Furthermore, there is a clear positive correlation between concentration and repellency. Further increasing the oregano essential oil concentration to 20% showed that 20% oregano essential oil achieved a 100% repellency rate against adult female fruit flies.

[0047] Example 2: The oviposition repellent effect of different concentrations of oregano essential oil on oriental fruit fly oviposition under non-selective experimental conditions.

[0048] Oregano essential oil was diluted with acetone to 1.25, 2.5, 5, 10, 20, 100, and 200 μL / mL as test samples.

[0049] Specific testing method: A non-selective experiment was conducted. 10 mL of each concentration of pesticide was sprayed onto clean, uniformly sized, and fully ripe banana fruits using a small sprayer. The control group was sprayed with an equal amount of acetone solvent. Subsequently, 25 healthy female oriental fruit flies at their peak oviposition period were introduced into the experimental cages and allowed to acclimatize for 24 hours. The control and treatment groups were placed in different experimental cages. After 24 hours, the number of eggs laid by the oriental fruit flies in the bananas was recorded. The results are shown in Table 1.

[0050] Table 1. Oviposition repellency activity of oregano essential oil against oriental fruit fly in non-selective experiments (24h)

[0051] Concentration (μL / mL) Egg production (grain / fruit) Egg production drive rate (%) CK 183.33±9.33 -- 1.25 147.33±4.73 19.93±4.75c 2.5 129.67±9.26 29.57±6.49c 5 75.67±4.67 58.57±3.17b 10 50.67±5.04 72.58 ± 1.94ab 20 24.67±3.51 86.48±1.54a 100 0.00±0.00 100.00±0.00 200 0.00±0.00 100.00±0.00

[0052] Note: The number of eggs laid and the rate of egg-laying avoidance in the table are the averages of three replicates, expressed as mean ± standard error; different letters in the same column indicate significant differences (P < 0.05).

[0053] Table 1 shows that under non-selective experimental conditions, oregano essential oil has an oviposition-repelling effect on oriental fruit flies, and the repelling effect increases with increasing concentration, reaching a maximum oviposition-repelling rate of 86.48% at 20 μL / mL. When the essential oil concentration is increased to 100 μL / mL, the repellency rate reaches 100.00%; when the concentration is further increased to 200 μL / mL, the repellency rate remains unchanged at 100.00%.

[0054] Example 3: The oviposition repellent effect of different concentrations of oregano essential oil on oriental fruit fly oviposition under selective experimental conditions.

[0055] Oregano essential oil was diluted with acetone to 1.25, 2.5, 5, 10, 20, 100, and 200 μL / mL as test samples.

[0056] Specific testing method: A selective experiment was conducted. Twenty-five healthy female oriental fruit flies at their peak oviposition period were introduced into experimental cages and allowed to acclimatize for 24 hours. 10 mL of each concentration of pesticide was sprayed onto clean, uniformly sized, and fully ripe banana fruits using a small sprayer. The control group was sprayed with an equal amount of acetone solvent. The control and treatment groups were then placed in the same experimental cages. After 24 hours, the number of eggs laid by the oriental fruit flies in the bananas was recorded. The results are shown in Table 2.

[0057] Table 2. Oviposition repellency activity of oregano essential oil against oriental fruit fly in selective experiments (24h)

[0058]

[0059]

[0060] Note: The egg production and egg-laying avoidance rate in the table are the averages of three replicates, expressed as mean ± standard error; different letters in the same column indicate significant differences (P < 0.05).

[0061] As shown in Table 2, under selective experimental conditions, the egg-laying rate was lower than that of the control group under different concentrations of oregano essential oil. The egg-laying repellency rate increased with increasing concentration, reaching a maximum of 69.27% ​​at 20 μL / mL, indicating excellent repellency activity. When the essential oil concentration was increased to 100 μL / mL, the repellency rate reached 100.00%; when the concentration was further increased to 200 μL / mL, the repellency rate remained unchanged at 100.00%.

[0062] The solvent for the above-mentioned oregano essential oil solution can also be any one or more of methanol, dimethyl sulfoxide, N,N-dimethylamide, vegetable oil, mineral oil, n-hexane, ethanol, ethyl acetate, and tetrahydrofuran, without changing the medicinal efficacy of oregano essential oil.

[0063] Example 4: Preparation of oregano essential oil fruit fly repellent

[0064] The solution composition of oregano essential oil fruit fly repellent is as follows: 10 mL of crude oregano essential oil, 15 mL of acetone solvent, 0.5 mL of Tween-80 emulsifier, 15 mL of ethanol, and distilled water to make up to 100 mL.

[0065] The specific preparation sequence is as follows: First, add 5 mL of acetone to a 100 mL volumetric flask, then add 10 mL of crude oregano essential oil to the flask, shake to mix, then add 10 mL of acetone and 15 mL of ethanol. Shake well, add 0.5 mL of Tween-80, and then sonicate to mix. Finally, add distilled water to bring the volume to 100 mL. Shake well and seal to obtain a 10% (100 μL / mL) soluble oregano essential oil fruit fly repellent.

[0066] The solvent in the above liquid can also be any one or more of methanol, dimethyl sulfoxide, N,N-dimethylamide, vegetable oil, mineral oil, n-hexane, ethyl acetate, and tetrahydrofuran.

[0067] The emulsifier in the above liquid can also be any one or more of Span 80, calcium dodecylbenzene sulfonate, polyoxyethylene dehydrated sorbitan oleate, and tea saponin.

[0068] The dosage form of oregano essential oil fruit fly repellent can also be any one of emulsifiable concentrate, wettable powder, water-dispersible granules, soluble granules, microemulsion, emulsion, effervescent tablets, suspension concentrate, or granules.

[0069] In other formulations of oregano essential oil repellents, depending on the nature of the formulation, pesticide formulation excipients may be added, including but not limited to any one or more of wetting and dispersing agents, thickeners, stabilizers, thixotropic agents, penetration enhancers, defoamers, antifreeze agents, and pH adjusters.

[0070] The wetting and dispersing agent may be selected from one or more of the following: sodium lignosulfonate, calcium lignosulfonate, sodium lauryl polyoxyethylene ether sulfate, alkyl naphthaldehyde condensate sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, potassium (sodium) oleate, alkyl polyoxyethylene ether sulfonate, alkylphenol polyoxyethylene ether formaldehyde condensate, alkylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, polyoxyethylene polyoxypropylene ether block copolymer, separating powder, sodium polyoxyethylene ester, dodecyl polyoxyethylene ether phosphate, alkyl naphthaldehyde condensate sulfonate, sodium methyl oleate aminoethyl sulfonate, alkyl acid polyoxyethylene ether sulfonate, starch, gelatin, hydroxymethyl cellulose, and polyvinyl alcohol.

[0071] The thickener may be selected from one or more of the following: xanthan gum, heteropolysaccharides, hydroxymethyl (ethyl) cellulose, methyl cellulose, gum arabic, guar gum, sodium alginate, carrageenan, pectin, polyvinyl alcohol, bentonite, synthetic hydrated silica, gypsum, acrylic polymers and magnesium aluminum silicate.

[0072] The stabilizer may be selected from one or more of the following: pyrogallol, butyl glycidyl ether, phenyl glycidyl ether, tolyl glycidyl ether, polyvinyl glycol diglycidyl ether, epichlorohydrin, sodium sorbate, sodium benzoate, epoxidized soybean oil, linseed oil, hydroquinone, anthraquinone, eugenol, BHA, BHT, VB, citric acid, ascorbic acid, PABA, hydroxybenzoate, propylparaben, pyrogallol, dihydroxybenzoic acid, FB-28, castor oil, olive oil, hydroquinone, dinaphthol, 1-naphthol, salicylic acid, rosemary oil, benzoic acid, and soluble starch.

[0073] The penetration enhancer can be one or more of the following: laurocapram or JFC.

[0074] The defoamer can be one or more of the following: silicone oil, silicones, C10-20 saturated fatty acids, C8-10 fatty alcohols, and 2-ethylhexanol.

[0075] The antifreeze can be selected from one or more of the following: ethylene glycol, glycerol, propylene glycol, polyethylene glycol, sorbitol, and urea.

[0076] The pH adjuster can be one or more of the following: sodium hydroxide, ammonia, acetic acid, hydrochloric acid, citric acid, and phosphoric acid.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description and ideas, and it is neither necessary nor possible to exhaustively describe all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. The application of oregano essential oil in repelling sexually mature female oregano fruit flies, characterized in that, Oregano essential oil is used as the active ingredient in repellents, and the concentration of oregano essential oil in repellents is 1.25–200 μL / mL.

2. The use of oregano essential oil as a fruit fly repellent and / or in the preparation of fruit fly repellents, characterized in that, The fruit fly is the oriental fruit fly, and the fruit fly repellent is a repellent for sexually mature adults and / or an oviposition repellent, containing an oregano essential oil solution at a concentration of 1.25–200 μL / mL.

3. The application according to claim 2, characterized in that, A solution containing oregano essential oil at a concentration of 100 μL / mL.

4. The application according to claim 2, characterized in that, The solvent for the oregano essential oil solution is any one or more of acetone, methanol, dimethyl sulfoxide, N,N-dimethylamide, vegetable oil, mineral oil, n-hexane, ethanol, ethyl acetate, and tetrahydrofuran.

5. The application according to claim 2, characterized in that, The solvent for the oregano essential oil solution is acetone.

6. The application according to claim 2, characterized in that, The fruit fly repellent is available in any one of the following formulations: soluble concentrate, emulsifiable concentrate, wettable powder, water-dispersible granules, soluble granules, microemulsion, emulsion, effervescent tablet, suspension concentrate, or granules.

7. The application according to claim 2, characterized in that, The fruit fly repellent also contains any one or more excipients commonly used in pesticide formulations, including wetting and dispersing agents, thickeners, stabilizers, thixotropic agents, penetration enhancers, defoamers, antifreeze agents, pH adjusters, and emulsifiers.

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