Insect repellent

Abstract

To provide a highly safe insect repellent containing a natural ingredient.SOLUTION: An insect repellent contains dendrolasin as an active ingredient.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a novel pest repellent. [Background technology]

[0002] For example, pyrethroid is a general term for pyrethrin, a natural component found in pyrethrum flowers, and its synthetic analogues. Because they have insecticidal and repellent (insect repellent) effects, many pest control agents that use pyrethroids as their active ingredient have been developed (e.g., Patent Documents 1 and 2). Pyrethroids are considered to be relatively safe, but there is hope for the development of new pest repellents made from natural ingredients that are safer for both humans and the environment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-118157 A [Patent Document 2] JP 2022-112279 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a highly safe pest repellent containing natural ingredients. [Means for solving the problem]

[0005] The pest repellent according to the present invention contains dendrolasin as an active ingredient. In the present invention, the dendrolasin is derived from ants and may further contain ant-derived components other than dendrolasin. Examples of ant-derived components other than dendrolazin include farnesal, α-citral, β-citral, α-citronellal, and β-citronellal. In the present invention, the pests to be repelled may be Diptera, and examples of Diptera include mosquitoes, black flies, pediculids, midges, and horseflies. One embodiment of the present invention is a method for repelling pests, which comprises applying the above-mentioned pest repellent to an object to be treated or its surroundings. For example, the repellent may be applied to a person's skin by painting, sprinkling, spraying, or the like. Effect of the Invention

[0006] According to the present invention, it is possible to provide a pest repellent which is excellent in safety and has a high repellent effect against pests. [Brief description of the drawings]

[0007] [Figure 1] The results of Test 1 are shown. [Diagram 2] The results of Test 2 are shown. [Diagram 3] The results of Test 3 are shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The pest repellent according to the present invention contains dendrolasin (β-[4,8-dimethyl-nona-3,7-dienyl]furan) as an active ingredient. Dendrolasin is a natural component obtained from plants and ants, and may be derived from plants, but in the present invention, it is preferably derived from ants. Examples of ants include the genus Acanthus including the subgenus Acanthus such as Acanthus nigricans and Acanthus hayashii, the subgenus Acanthus such as Acanthus nigricans and Acanthus fujibosokusa, the subgenus Acanthus amplexicaule such as Acanthus miyamaensis and Acanthus longifolia such as Acanthus nigricans, and the subgenus Acanthus melongena such as Acanthus minamiensis and Acanthus dwarf yellow, with the subgenus Acanthus being preferred, and Acanthus nigricans being more preferred. There are no particular limitations on the method for extracting dendrolasin, but since dendrolasin is found in large amounts in the secretions from the mandibular glands of ants, dendrolasin may be extracted, for example, by immersing the heads of ants in diethyl ether or the like for a predetermined period of time.

[0009] The pest repellent of the present invention may contain an ant-derived component other than dendrolazin. Examples of ant-derived components other than dendrolazin include farnesal, α-citral, β-citral, α-citronellal, and β-citronellal. α-Citronellal and β-citronellal have a hawthorn-like aroma, while α-citral and β-citral have a lemon-like aroma, and farnesal is also one of the components that contribute to the aroma. Citronellal and citral are volatile and already known to have repellent effects. The pest repellent of the present invention contains dendrolasin as an active ingredient, which is less volatile than citronellal and the like, and is therefore expected to have a high and long-lasting repellent effect against pests.

[0010] In the present invention, the pests to be repelled are Diptera, such as mosquitoes, black flies, pediculids, midges, and horseflies. For example, mosquitoes include mosquitoes of the Aedes genus, such as Aedes albopictus, Aedes yamada, Aedes yamatoensis, Aedes vexans, and Aedes aegypti, mosquitoes of the Culex genus, such as Culex tritaeniorhynchus, Culex pipiens molestus, and Culex quinquefasciatus, and mosquitoes of the Anopheles genus, such as Anopheles sinensis. Examples of pediculidae flies include flies of the family Hippocampidae, such as the sheep pediculidae, the horse pediculidae, and the dog pediculidae.

[0011] Pest repellents containing dendrolasin as an active ingredient can be formulated by combining it with ant-derived components other than dendrolasin, as well as optional ingredients and carriers used in conventional pest repellents. For example, dendrolasin or ant-derived components can be used as is, or can be dissolved or solubilized in a solvent (medium) to form a liquid formulation, or can be supported on a carrier to form a solid formulation, and can be prepared into pump formulations, aerosol formulations, liniments, mat formulations, sheets, tapes, gels, creams, etc. to serve as pest repellents. Optional components may include, for example, solvents, surfactants, wetting agents, stabilizers, propellants, bactericides, fungicides, fragrances, water and oil repellents, etc., and may also be used together with other insect repellents such as pyrethroids. The content of dendrolasin in the pest repellent of the present invention can be appropriately determined depending on the formulation of the pest repellent and the target of application, etc., but for example, when the pest repellent is a liquid formulation, the content of dendrolasin relative to the total amount of liquid is preferably 21 mass% or more, more preferably 67 mass% or more, and even more preferably 90 mass% or more. The pest repellent of the present invention can be applied to an object to be applied or to a specified portion thereof or its surroundings to repel pests from the object to be applied or its surroundings, or it can be supported on a carrier such as a sheet and placed in a location where it is desired to repel pests. Examples of objects to which the composition can be applied include, but are not limited to, people, flowerpots, planters, etc., and methods for applying the composition to objects to which the composition can be applied include coating, scattering, spraying, etc. EXAMPLES

[0012] The present invention will now be described in detail, but the present invention is not limited to these examples.

[0013] <GC-MS analysis of ant-derived components> Worker ants of the false grass ant and the rhinoceros grass ant were collected from the field, and 5 to 8 individuals of each species were placed in each vial. The vials were then stimulated by vibrating them or tapping them lightly with a glass rod, causing the ants to secrete secretions from their mandibular glands. After removing the ants from each vial, an adsorbent (MonoTrap(R) RSC18, GL Sciences) was placed into the vial, and the adsorbent that had adsorbed the secretions was immersed in 200 μl of diethyl ether at 20°C for 5 minutes, and the extracted components were analyzed by GC-MS. GC-MS analysis was performed using a Shimadzu GCMS-QP5000 system connected to a Shimadzu GC-17A chromatograph equipped with a DB-WAX (30 m × 0.25 mm × 0.25 μm, Agilent J&W) column with helium as the carrier gas at a head pressure of 63 kPa. The analytical conditions were as follows: the inlet and detector temperatures were set at 220°C, and the column oven temperature was maintained at 40°C for 5 min, then programmed to 220°C at a rate of 5°C / min, and the final temperature was maintained for 20 min. The area ratio of each component to the total GC peak area was calculated for each individual ant, and the average value and standard deviation for each ant were calculated. The results are shown in Tables 1 and 2. The range indicates the range from the lower limit to the upper limit for the value of each individual ant. [Table 1] [Table 2]

[0014] As shown in Table 1, the secretions of the grass ant contained approximately 70% by mass (hereinafter simply referred to as %) of dendrolasin, as well as approximately 15% β-citronellal and approximately 1% farnesal. On the other hand, as shown in Table 2, the Fujibosokusa ant contained approximately 31% dendrolasin, approximately 20% farnesal, approximately 15% α-citral, approximately 11% β-citral, and approximately 5% α-citronellal. This shows that the content of dendrolasin in the secretions varies depending on the ant, and that the ant-derived components other than dendrolasin are different, but the proportion of dendrolasin in the secretions is high.

[0015] <Test 1: Mosquito repellent test using Dendrolasin> Dendrolasin isolated from the two ants was extracted and dissolved in hexane to prepare a 90% dendrolasin solution. Approximately 0.5 ml of this dendrolasin solution was soaked on a cotton swab and brought close to Aedes albopictus and Aedes mosquitoes in a mesh cage (35 cm x 20 cm x 20 cm), and their reaction to dendrolasin was observed. As controls, similar tests were performed using untreated cotton swabs or cotton swabs soaked in hexane only. A total of 140 mice were tested in 7 trials, with 20 mice counted as one trial. Furthermore, among the 140 mosquitoes, the proportion of Aedes albopictus mosquitoes was higher than that of Aedes mosquitoes. The results are shown in Figure 1.

[0016] Figure 1(a) shows the average number of mosquitoes (per trial) that escaped when exposed to a dendrolasin solution obtained from the false grass ant, and (b) shows the average number of mosquitoes that escaped when exposed to a dendrolasin solution obtained from the Japanese ant, the Fujiboshi grass ant. When mosquitoes were approached with cotton swabs soaked in a solution of dendrolasin obtained from each ant, they flew away frequently, and the average number of mosquitoes that escaped within 5 seconds was significantly higher than the control for both species. One-way ANOVA showed that the grass ant was F 2,18 =235.4, Fujibosokusa ant is F 2,18 =29.8.

[0017] <Test 2: Mosquito repellent test using ant-derived ingredients> The heads, including the mandibles of the false grass ant and the Japanese larvae, were separated from the thorax and abdomen, and the heads were immersed in 50 mL of diethyl ether for more than 20 minutes. The extract was then dissolved in hexane and developed using an open column chromatography packed with 10 g of 230-400 mesh silica gel (Merck). Each fraction obtained by fractionation using a hexane / diethyl ether mixed solvent system was also analyzed by GC-MS. As a result, the dendrolasin ratio was highest in the head of each ant, and the dendrolasin ratio in the secretions from the ants' mandibular glands was roughly similar to the dendrolasin ratio in the head. Therefore, the heads of three individuals each of the false grass ant and the Japanese bush ant were rubbed against a 5 cm x 5 cm bird feather, and a repellent test was conducted on the feather against Aedes albopictus and Aedes mosquitoes. Specifically, 0.3 ml of each ant-derived component containing dendrolasiacin was applied thinly to a kite wing so that the component was spread evenly. The wing was then placed in a mesh cage containing approximately 100 Aedes albopictus and Yamada mosquitoes for 10 minutes, and the number of mosquitoes that remained stationary for more than 5 seconds was counted. As a control, the same test was performed using untreated feathers, and 20 tests were performed for each species. The results are shown in Figure 2.

[0018] Figure 2(a) shows the average number (per trial) of mosquitoes that stayed on a wing coated with ant-derived components obtained from the false grass ant, and (b) shows the average number (per trial) of mosquitoes that stayed on a wing coated with ant-derived components obtained from the Japanese ant, Fujiboso grass ant. Mosquitoes landed on the wings coated with each ant-derived component but then quickly flew away, and the average number of mosquitoes that landed on them was significantly lower than in the control. The t-test results were t=57.2 for the pseudoweed ant and t=25.2 for the Fujiwara weed ant.

[0019] <Test 3: Mosquito repellent test on humans using ant-derived ingredients> The heads of three individuals each of the false grass ant and the Fujiboso grass ant were rubbed against a person's arm (from the back of the hand to the forearm), and a repellent test was conducted on the arm against Aedes albopictus and Aedes mosquitoes. Specifically, 0.3 ml of each ant-derived ingredient containing dendrolasiacin was applied thinly to one arm so that the ingredient was spread evenly, and the arm was then inserted up to the elbow into a mesh cage containing approximately 100 Aedes albopictus and Yamada mosquitoes for one minute, and the number of mosquitoes that remained on the arm for more than five seconds was counted. As a control, a similar test was performed on the other untreated arm. The test was performed 12 times, and the number of mosquito bites was counted after each test. The results are shown in Figure 3.

[0020] Figure 3(a) shows the average number of mosquitoes (per trial) that stayed for more than 5 seconds on an arm that had been applied with ant-derived components obtained from the false grass ant, and (b) shows the average number of mosquitoes (per trial) that stayed for more than 5 seconds on an arm that had been applied with ant-derived components obtained from the Japanese ant, Fujiboso grass ant. Figures 3(c) and (d) show the number of bloodsucking marks on the arms where each ant-derived component was applied. When the ant-derived ingredient was applied, the average number of mosquitoes that landed was significantly lower (t-test: t=34.9 for the false grass ant, t=27.2 for the Japanese hawkweed ant), and the number of blood-sucking marks was also significantly lower (χ 2 The test is that the grass ant is χ 2 = 0.43, P < 0.001 for the Fujiboshi ant, χ 2 =0.42). Furthermore, there was no particular change in the condition of the arms to which the ant-derived ingredients were applied, confirming that the ingredients are safe. From the above, it can be seen that dendrolasin, a natural component found in the false grass ant and the Fujiboso grass ant, repels mosquitoes, which are Diptera, and has an insect repellent effect.

Claims

1. A pest repellent comprising dendrolasin, all of which are derived from ants, and one or more compounds selected from the group consisting of farnesal, α-citral, β-citral, α-citronellal and β-citronellal, wherein the pests to be repelled are Diptera.

2. A pest repellent as described in claim 1, which contains the most dendrolasin relative to the total amount, and which contains 21 mass% or more of dendrolasin relative to the total amount.

3. A method for producing the pest repellent according to claim 1 or 2, characterized in that dendrolasin and one or more compounds selected from the group consisting of farnesal, α-citral, β-citral, α-citronellal and β-citronellal are obtained without isolation by causing ants to secrete a secretion and / or immersing ants in an organic solvent and / or rubbing ants against the organic solvent.

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