Plant-derived repellent and its use in repelling tropical stink bugs and red fire ants

Abstract

The invention discloses a plant-derived repellent and its application in repelling tropical bed bugs and fire ants. The invention screens out three active ingredients of Chinese herbal essential oils, namely, α-ionone, citronellyl acetate and lilyal, wherein α-ionone and lilyal are derived from sandalwood, and citronellyl acetate is derived from citronella, and it is confirmed that the three substances have significant repellent effects on tropical bed bugs and fire ants. α-ionone, citronellyl acetate and lilyal are pure natural active substances of plant origin, have no toxic side effects on human body and environment, and are particularly suitable for preventing and controlling tropical bed bugs and fire ants in places where people live or often move.

Description

Technical Field

[0001] The invention belongs to the technical field of prevention and control of urban health pests, and particularly relates to a plant-based repellent and application thereof in repelling tropical stink bugs and red fire ants. Background Art

[0002] The tropical bed bug Cimex hemipterus (F.) is an important obligate blood-sucking insect that feeds on the blood of humans and a variety of animals. The bites and blood-sucking of the insect can cause many discomforts to the human body: for example, not only will the bitten part have symptoms such as papules, erythema, edema and itching, but also skin damage and secondary bacterial infection caused by scratching; the elderly and those with poor physical fitness may also suffer from anemia after being bitten; long-term bites and blood-sucking by bed bugs will induce psychological diseases such as insomnia, anxiety, and depression, and even worse, it will lead to suicide. In addition, more and more studies have confirmed that pathogens such as Bartonella quintana, Borrelia recurrentis, and Trypanosoma cruzi can be detected in the bodies and feces of tropical bed bugs. Therefore, tropical bed bugs may also become an important vector of human diseases. In my country, tropical bed bugs are mainly distributed in southern China, with the most serious outbreak in the Pearl River Delta. The bugs are concentrated in places with high population density and high population mobility, such as dormitories, rental houses, train carriages, and military camps. Currently, the prevention and control of tropical bed bugs relies too much on chemical insecticides such as pyrethroids, organophosphates and carbamates, neonicotinoids, and halogenated pyrroles. However, simple chemical control will not only lead to further aggravation of tropical bed bugs' resistance, but also pose a great threat to human safety. Therefore, exploring efficient and safe prevention and control measures and products has become a key issue that needs to be urgently addressed in the effective prevention and control of tropical bed bugs.

[0003] Red fire ants are one of the most dangerous invasive species in the world. Since the 1930s, they have invaded North America, Australia, Asia and other countries and regions, posing serious threats to agricultural and forestry production, human and animal health, and biodiversity. Since the red fire ants invaded my country in 2004, they have been common in southern provinces of mainland China. Since red fire ants have many ways to spread, have obvious population competitive advantages and strong reproductive capacity, and have no natural enemies to inhibit them in new invasion areas, they are quite difficult to control. At present, the prevention and control of red fire ants mainly relies on chemical control. Its disadvantage is that the entire red fire ant-infested area needs to be treated, otherwise the red fire ants will invade again. In addition, the improper use of chemical agents can easily lead to serious "3R" problems. Therefore, it is of great practical significance to find harmless red fire ant control technology and products.

[0004] As an alternative to chemical insecticides, repellents are substances that prevent insects from identifying and finding their biting / damaging targets, thus keeping them away from potential targets. Compared with insecticides, repellents have good advantages in terms of pest resistance and environmental friendliness. As a type of pure plant extract, the application potential of Chinese herbal essential oils in pest control has gradually attracted the attention of scientific researchers. At present, the research and application of the repellent effect of Chinese herbal essential oils are mainly carried out on mosquitoes, and Chinese herbal essential oils with mosquito repellent activity include: citronella oil, eucalyptus oil, peppermint oil, clove oil, cinnamon oil, camphor oil, etc. In addition, Chinese herbal essential oils such as menthol, borneol, isoborneol and camphor also have significant repellent effects on ants.

[0005] However, previous studies have mostly focused on the evaluation of the pest repellent effect of plant essential oils, and rarely explored the repellent active substances. The complex essential oil composition often affects the effect of the repellent active substances and can easily lead to a significant increase in the production cost of the repellent, thereby affecting the production and promotion of plant essential oil repellents. Summary of the invention

[0006] The invention aims to provide plant-derived repellents α-ionone, citronellal acetate and lilyral and their use in repelling tropical stink bugs and red fire ants.

[0007] Through a large number of preliminary experiments, the inventors screened out three active ingredients of Chinese herbal essential oils: α-ionone, citronellal and lilyal (α-ionone and lilyal come from sandalwood, and citronellal comes from citronella), and confirmed that these three substances have significant repellent effects on tropical bedbugs and red fire ants.

[0008] The first object of the present invention is to provide a plant-based repellent for tropical stink bugs and red fire ants, comprising a plant-based active component and a repellent carrier; the plant-based active component is any one of α-ionone, citronellal and lilyral, or a combination of two or more thereof.

[0009] Preferably, the repellent carrier is ethanol or n-hexane.

[0010] Preferably, the concentration of the plant-derived active component in the plant-derived repellent is 1% by volume or more. For example, if the concentration of the plant-derived active component in the plant-derived repellent is 1%, 2%, 3%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, etc., a good repellent effect can be achieved.

[0011] Preferably, the concentration of the plant-derived active component in the plant-derived repellent is 10% or 20% by volume.

[0012] The second object of the present invention is to provide the use of α-ionone, citronellal and / or lilyral in repelling tropical bed bugs and red fire ants.

[0013] Preferably, in the application, any one of α-ionone, citronellal and lilyral or a combination of two or more thereof is used as an active ingredient in a tropical stink bug and red fire ant repellent, and the concentration of the active ingredient in the repellent is 1% by volume or more.

[0014] Preferably, the concentration of the active ingredient in the plant-derived repellent is 10% by volume.

[0015] Preferably, the concentration of the active ingredient in the plant-derived repellent is 20% by volume.

[0016] Preferably, the application comprises the following steps: for repelling tropical bed bugs, spraying or applying the repellent on the surface of a bed, a sofa, a chair leg, a suitcase and / or clothing.

[0017] Preferably, the application comprises the following steps: for repelling red fire ants, the repellent is sprayed on the place where the red fire ants need to be prevented.

[0018] The α-ionone and lilyral involved in the present invention come from sandalwood, and citronellal acetate comes from citronella. These three components are all pure natural substances, have a specific fragrance, are environmentally friendly and have no toxic side effects, and are soluble in various organic solvents such as ethanol and n-hexane.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] Based on the current situation that tropical bed bugs and red fire ants are becoming increasingly rampant and there is a lack of pure natural repellents, three active substances in Chinese herbal essential oils with strong repellent effects on tropical bed bugs and red fire ants were screened out through a series of experiments. They are α-ionone, citronellal and lily of the valley aldehyde, all of which are pure natural repellents.

[0021] Previous studies have rarely explored repellent active substances. Complex essential oil components often affect the effect of repellent active substances and easily lead to a significant increase in the production cost of repellents, thereby affecting the production and promotion of plant essential oil repellents. The present invention can effectively reduce the application cost by exploring efficient repellent active substances.

[0022] The active components of the Chinese herbal essential oil, α-ionone, citronellal and lilyral, used in the present invention are all natural active substances, have no toxic side effects on human body and environment, are more suitable for preventing and controlling tropical bed bugs and red fire ants in places where people live or frequently move, and are highly effective and safe pest repellents.

[0023] On the one hand, the present invention can accelerate the pace of development and promotion of pure natural repellents for tropical bed bugs and red fire ants, and on the other hand, it can provide technical and product support for the precise prevention and control of tropical bed bugs and red fire ants, thereby effectively protecting the personal safety of residents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a design diagram of an experiment comparing the repellent effects of α-ionone, citronellal and lily of the valley aldehyde on tropical bed bugs (Petri dish method).

[0025] Figure 2 This is a comparative diagram of the repellent effects of α-ionone, citronellal and lilyal on tropical bed bugs (Petri dish method); in the figure, repellency index = (CT) / C*100%, where C is the average number of bed bugs staying in the n-hexane-treated area in the control group, and T is the number of bed bugs staying in the compound-treated area in the treatment group; the same lowercase letters in the figure indicate that there is no significant difference (α=0.05) between different treatments (different substances) at the same treatment time point.

[0026] Figure 3 This is a design diagram of an experiment comparing the repellent effects of α-ionone, citronellal and lily of the valley aldehyde on tropical bed bugs (trap method).

[0027] Figure 4 This is a comparative chart of the repellent effects of α-ionone, citronellal and lily of the valley aldehyde on tropical bed bugs (trap method); the percentage of bed bugs captured in the figure = the number of bed bugs captured by each trap / the total number of bed bugs captured by four traps*100%; different lowercase letters in the figure indicate significant differences (α=0.05) among different treatments (different substances) at the same treatment time point.

[0028] Figure 5 This is the design diagram of the experiment on the interference of α-ionone, citronellal and lily of the valley aldehyde on the aggregation behavior of tropical bed bugs.

[0029] Figure 6 This is a comparison of the effects of α-ionone, citronellal and lily of the valley aldehyde on the aggregation behavior of tropical bed bugs. The percentage of bed bugs choosing paper pieces with different treatments was analyzed using the chi-square test, *: P<0.05, **: P<0.01, ***: P<0.001.

[0030] Figure 7 This is the design diagram of the experiment on the repellency of red fire ants by three substances: α-ionone, citronellal and lily of the valley aldehyde.

[0031] Figure 8This is a comparative chart of the repellent effects of α-ionone, citronellal and lily of the valley aldehyde on red fire ants; the percentage of sand dug out in the figure = the amount of sand dug out in each sample bottle / the total amount of sand dug out in two sample bottles*100%; the percentage of sand dug out in the figure was analyzed using a paired t-test, ****: P<0.001. DETAILED DESCRIPTION

[0032] The following examples are provided to further illustrate the present invention, rather than to limit the present invention.

[0033] The α-ionone involved in the following examples was purchased from Nanjing Dulai Biotechnology Co., Ltd. with a purity of ≥90%; citronellal was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd. with a purity of 95%; and lilyral was purchased from Shanghai Mairui Biochemical Technology Co., Ltd. with a purity of 97%.

[0034] Example 1: Repellent effects of three substances on tropical bed bugs (Petri dish method)

[0035] Experimental method: A glass petri dish with a diameter of 14.5 cm and a height of 2 cm was used as the experimental device. A layer of polytetrafluoroethylene was applied to the inner wall of the petri dish to prevent tropical bed bugs from escaping, and a piece of filter paper was attached to the bottom of the petri dish. The filter paper was evenly divided into two halves, and one half was sprayed with 0.1 mL / mL of a hexane solution of the active ingredients of Chinese herbal essential oils (α-ionone, citronellal or lilyral), and the spraying amount was 12.1 μL / cm 2 , and the other half was sprayed with an equal amount of 95% n-hexane; in the control group, half of the filter paper was sprayed with 95% n-hexane, and the other half of the filter paper was not treated; the treated filter paper was placed under laboratory conditions for 1-2 hours to allow it to dry thoroughly. A small tent harborage (folded with filter paper) with a length of 2 cm, a width of 1 cm, and a height of 0.5 cm was glued to the filter paper in the treatment area. The small tent was treated in the same way as above, that is, the small tent in the culture dish of the treatment group was treated with a n-hexane solution of the active ingredient of Chinese herbal essential oil, and the small tent in the culture dish of the control group was treated with n-hexane. After the filter paper was pasted, 10 male adults of tropical bed bugs were introduced into each culture dish, and the experiment was started at the same time. The number of bed bugs on the filter paper with different treatments in each culture dish was recorded at 2, 4, and 6 hours after the start of the experiment. n-Hexane vs blank control, α-ionone vs n-hexane, citronellal vs n-hexane, and lily of the valley aldehyde vs n-hexane were recorded as different treatments, and each treatment was repeated 6 times. The experimental design is as follows Figure 1 shown.

[0036] Results: In the absence of host odor, α-ionone, citronellal and lilyal all had strong repellent effects on tropical bed bugs, and there was no significant difference in the repellent effects of the three on tropical bed bugs. Figure 2 shown.

[0037] Example 2: Repellent effects of three substances on tropical bed bugs (trap method)

[0038] Experimental method: A plastic tray with a length of 95 cm, a width of 75 cm, and a height of 10 cm was used as the experimental area. A piece of kraft paper was laid on the bottom of the tray to facilitate the activities of tropical bed bugs. A layer of polytetrafluoroethylene was applied to the inner wall of the tray to prevent tropical bed bugs from escaping. 12-14 hours before the start of the experiment, a plastic circle with a diameter of 6.5 cm and a height of 5 cm was placed in the center of the tray. A layer of polytetrafluoroethylene was applied to the inner wall of the plastic circle. A piece of paper with a length of 4 cm and a width of 3 cm was placed in the plastic circle (folded into a tent shape to provide a hiding place for tropical bed bugs), and 100 tropical bed bugs (50 males and 50 3-5 instar nymphs) were introduced. 1-2 hours after entering the dark cycle, a square wooden bench was placed in the center of the tray, and the four legs of the bench were placed in the center of four ClimbUp bed bug monitors (15.24 cm in diameter and 2.3 cm in height). The inner wall of the monitor was coated with a layer of polytetrafluoroethylene, and the outer wall was pasted with medical tape to facilitate bed bugs to climb. A 0.2 mL / mL n-hexane solution of the active ingredients of Chinese herbal essential oils (α-ionone, citronellal, or lilyral) was applied to the surface of the medical tape, and the amount applied was 9.1 μL / cm 2 , and the control was coated with an equal amount of 95% n-hexane. The distance between the center of each monitor and the bed bug release point was 16 cm. A glass bottle connected to a CO2 cylinder was placed above the bench, and CO2 was released at a rate of 220 mL / min (simulating the host's breathing). At the same time, the plastic ring that restricted the activity of bed bugs was removed, and the experiment began immediately. The number of bed bugs captured in each monitor was recorded 1, 2, and 6 hours after the start of the experiment. This experiment was repeated 4 times. The experimental design is as follows Figure 3 shown.

[0039] Results: In the presence of CO2 gas, the repellent effects of α-ionone and citronellal acetate on tropical bed bugs were significantly better than the blank control (n-hexane) at 1, 2 and 6 hours after treatment (P<0.05); the repellent effect of lily of the valley aldehyde on tropical bed bugs was significantly better than the blank control (n-hexane) at 1 hour after treatment (P<0.05). Among the three compounds, α-ionone had the best repellent effect. It could effectively repel tropical bed bugs after being applied to the surface of the monitor. The number of bed bugs captured at 1, 2 and 6 hours after treatment accounted for 9.6%, 9.7% and 9.3% of the total number of captured bed bugs, respectively. The results are shown in Table 1. Figure 4 shown.

[0040] Example 3: Interference of three substances on the aggregation behavior of tropical bed bugs

[0041] Experimental method: A glass petri dish with a diameter of 9 cm and a height of 1.5 cm was used as the experimental device. Filter paper was pasted on the bottom of the petri dish to facilitate the crawling of tropical bed bugs, and a layer of polytetrafluoroethylene coating was applied to the inner wall to prevent bed bugs from escaping. 12 hours before the experiment, a single male adult tropical bed bug was introduced into the plastic circle in the center of the petri dish to acclimate to the environment. The plastic circle was made of a plastic petri dish with a diameter of 3 cm and a height of 1 cm. The bottom of the petri dish was removed and a layer of polytetrafluoroethylene coating was also applied to the inner wall. After 1-2 hours of entering the light cycle, two pieces of cardboard (1 cm long and 1 cm wide) containing tropical bed bug feces were folded into a small tent and placed in the petri dish. The distance between the two pieces of cardboard and the center of the bed bug release point was 4 cm. One of the cardboards was dripped with 50 μL of n-hexane solution as a control, and the other cardboard was dripped with 50 μL of n-hexane solution (concentration of 0.2 mL / mL) of active ingredients of Chinese herbal essential oils (α-ionone, citronellal or lilysinal). The plastic ring that restricted the bed bugs was removed and the experiment was started. The position of the tropical bed bugs in the petri dish was recorded after 24 hours. The experiment was repeated 12 times. Figure 5 shown.

[0042] Results: The percentage of tropical bed bugs choosing paper discs treated with active ingredients of Chinese herbal essential oils was significantly lower than that treated with n-hexane (P<0.05). The paper discs treated with citronella acetate had a 100% repellency rate against tropical bed bugs. This indicates that α-ionone, citronella acetate and lilyral can significantly interfere with the aggregation behavior of tropical bed bugs. Figure 6 shown.

[0043] Example 4: Repellent effects of three substances on red fire ants

[0044] Experimental method: In this experiment, a plastic petri dish with a diameter of 16 cm and a height of 6 cm was selected as the experimental device. Two bisectors were drawn at the bottom of the petri dish, and holes were punched at both ends of one of the bisectors. The distance between each hole and the center of the circle was 6 cm, and the diameter of each hole was 3 mm. The hole was connected to a 5 mL glass sample bottle; the other bisector was not punched at both ends, but only connected to the sample bottle to play a supporting role. The specific operation steps are as follows: first, the sample bottle cap was glued to the bottom of the petri dish with hot melt glue, and then the bottom of the petri dish and the sample bottle cap were punched with a hole puncher. A layer of polytetrafluoroethylene coating was evenly applied to the inner wall of the petri dish to prevent red fire ants from escaping. Before the experiment, the fine sand was treated with a 0.01 mL / mL hexane solution of the active ingredients of Chinese herbal essential oils (α-ionone, citronellal or lily of the valley aldehyde), and the ratio of sand to solution was 20:2; the fine sand of the control group was treated with an equal amount of 95% hexane. The treated fine sand was naturally air-dried for 5 minutes under indoor conditions, and then distilled water was added to moisten it. The ratio of sand to distilled water was 20:1.2. The moistened fine sand was then placed in a glass sample bottle. 20 red fire ant workers were introduced to the center of the culture dish and the experiment began. After 24 hours, the weight of the fine sand dug out by the red fire ants in the sample bottles of each treatment (active substance VS control) was weighed to determine the repellent effect of each treatment on the red fire ants. The experiment was repeated 6 times. The experimental design is as follows Figure 7 shown.

[0045] Results: The experimental results showed that the amount of sand dug out by red fire ants in the sample bottles treated with α-ionone, citronellal and lilyal was significantly lower than that in the control (P<0.001), indicating that the three active ingredients of Chinese herbal essential oils, α-ionone, citronellal and lilyal, have a strong repellent effect on red fire ants. Figure 8 shown.

[0046] Conclusion: α-ionone, citronellal and lilyral, the three active ingredients of Chinese herbal essential oils, have strong repellent effects on tropical bed bugs and red imported fire ants, and can be used as safe repellents for these two urban / sanitary pests.

[0047] The three active ingredients of Chinese herbal essential oils mentioned above: α-ionone, citronellyl acetate and lilyal can effectively interfere with the activities of tropical bed bugs and the perception of aggregation pheromones, and can be used to treat the surfaces or gaps of beds, sofas, suitcases, clothing, etc., to achieve the purpose of effectively repelling tropical bed bugs. In the presence of host odor (carbon dioxide), α-ionone and citronellyl acetate are applied to the surface of bed legs and sofa legs, which can reduce the probability of tropical bed bugs climbing onto the bed or sofa to a certain extent, thereby greatly reducing the possibility of residents being bitten and sucked blood by bed bugs. In addition, α-ionone, citronellyl acetate and lilyal can repel red fire ants. The application of these three substances can effectively prevent red fire ants from nesting in residential activity areas or areas that need to be protected, and can also block the spread of red fire ants to a certain extent. Since the above substances are all pure natural active ingredients of Chinese herbal essential oils, they are harmless to the human body and the environment, and are particularly suitable for the prevention and control of tropical bed bugs and red fire ants in places where people live or often move.

Claims

1. Application of lily of the valley aldehyde in repelling tropical bed bugs.

2. The use according to claim 1, characterized in that: The lily of the valley aldehyde is used as an effective component in the tropical bed bug repellent, and the concentration is more than 1% by volume.

3. The use according to claim 2, characterized in that: The concentration of the active ingredient in the tropical bed bug repellent is 10% by volume.

4. The use according to claim 2, characterized in that: The concentration of the active ingredient in the tropical bed bug repellent is 20% by volume.

5. The use according to claim 2, characterized in that: The following steps are involved: To repel tropical bed bugs, spray or apply the repellent to beds, sofas, chair legs, luggage, and / or clothing.

Images