JP5952997B2 - Termite control method - Google Patents

Description

  The present invention relates to a method for controlling termites.

  Conventionally, chemical control using chemicals is mainly used for termite control, but less chemical methods that use less chemicals and non-chemical methods that do not use chemicals (biological control and physical control) are also used. ing.

  Chemical control uses pyrethroids, neonicotinoids, and other organic chemicals and sprays them under the floor to form a chemical barrier that prevents termites from entering and is effective quickly and accurately. It has a wide application range and is the cheapest and most reliable method among the control methods. A bait method that applies drugs that have an effect on insects, such as termites, only to the place where termites are terrified, or a sheet method that suppresses the outflow of drugs to other locations by mixing drugs in polymer sheets Has been devised and put into practical use as a less chemical method.

  Biological control in the non-chemical method is a method for controlling insects such as termites that are hosts by using microorganisms or nematodes parasitic on insects such as termites. Physical control is a method that prevents the entry of termites from under the floor by laying a stainless mesh under the building or laying pebbles on the ground under the floor. Control by vibration, heating, cooling, radiation, electric shock, etc. has been studied and partly put into practical use. It has been pointed out that such physical control requires installation at the beginning of construction and generally requires a considerably high cost. Therefore, as a method of physically controlling termites at a relatively low cost, a method has been proposed in which an ultraviolet irradiation device is installed under the floor of a building using the habit of instinctively avoiding termites when they sense ultraviolet rays. (Patent Document 1).

  However, in the method using the ultraviolet irradiation device, since ultraviolet rays are also irradiated to a house member such as a wood under the floor, the surface layer of the member is deteriorated by ultraviolet rays such as a decrease in strength and discoloration. In addition, since ultraviolet rays are not visible to the eyes, it is difficult to confirm the irradiation status, and there are problems such as the human body being exposed to ultraviolet rays and being adversely affected when checking the irradiation status. It is.

JP 2001-321055 A

  The problem to be solved by the present invention is to provide a termite control method that is safe for the human body without causing a decrease in strength or discoloration of a house member such as wood under the floor.

  The present inventors have studied the termite repelling behavior. As a result, the present inventors have found that termites repel visible light having a specific wavelength, and have completed the present invention.

  That is, the present invention relates to a method for controlling termites, which comprises irradiating termites with visible light having a wavelength of 400 to 550 nm, preferably 400 to 450 nm.

  In the present invention, since ultraviolet rays are not used, the strength and discoloration of a housing member such as wood under the floor are not caused, and the human body is not adversely affected.

Explanatory drawing of the test apparatus used in the Example. The graph which showed the termite light place presence rate (%) in the different wavelength in case the photon flux density is constant 60μmol / m ² / s. The graph which showed the termite light place abundance ratio (%) 30 seconds after the start of irradiation in different photon flux densities when the wavelength is constant 400 nm. The graph which showed the termite light place abundance ratio (%) 30 seconds after the start of irradiation in the different photon flux density when the wavelength is 425 nm.

  Hereinafter, embodiments of the present invention will be described.

  In the control of termites by light irradiation, it is important that the housing members are not easily deteriorated, the influence on the human body is small, and the irradiation status is easy to confirm. Therefore, a control method using visible light, which is completely different from the conventional control method using ultraviolet rays, was examined. If visible light is used, it is difficult to cause deterioration of the housing members, and the influence on the human body is small. Further, when used in a termite control system, it is considered that if it is visible light, the irradiation status can be easily confirmed.

  Regarding the behavioral characteristics (phototaxis) of termites with respect to light, differences due to the class of termites have been reported so far. However, there are few reports on ants and soldiers that make up the majority of termite nests and are actually involved in the damage to buildings, and evaluation is performed without precisely controlling the wavelength of the light source. It was. For this reason, it has been reported that termite craftsmen and soldier ants irradiated with incandescent lamps that contain visible light may exhibit repellent behavior (negative phototaxis). It was unclear how much repellent behavior (negative phototaxis) was exhibited.

  Therefore, in the present invention, first, termite worker ants and soldier ants were irradiated using approximate monochromatic light in which the wavelength of light was precisely controlled, and the influence of the wavelength on the phototaxis was examined closely. As a result, we found that craft ants and soldier ants irradiated with visible light having a wavelength of 400 to 550 nm show repellent behavior (negative phototaxis). In particular, when visible light having a wavelength of 400 to 450 nm was used, the repellent effect was high, and the same repellent effect as that obtained when ultraviolet rays were used was obtained. In other words, if you use visible light with a wavelength of 400-550 nm instead of conventional ultraviolet light, you can physically control termite ants and soldiers, especially when using visible light with a wavelength of 400-450 nm. Clarified that the same high control effect as that obtained when ultraviolet rays were used was obtained, and the present invention was achieved.

  In order to control termites by the method of the present invention, a light source capable of irradiating visible light having a wavelength of 400 to 550 nm is installed on a member of an underfloor space of a building, etc., and irradiated to the ground under the floor or the rising part of the foundation. This prevents termites from entering under the floor. Moreover, according to the kind of termite and the intrusion situation of a termite, it irradiates each structural member place including an attic etc., and the invasion of a termite is prevented.

  The irradiation light source may be approximate monochromatic light with a narrow wavelength width that is finely divided as in the above example, but any type (if it can irradiate visible light with a wavelength of 400 to 550 nm with an effective light amount) LED, fluorescent light, incandescent light source).

As for the amount of irradiation light, in the case of approximate monochromatic light that has been dispersed with a wavelength band of 25 nm as in the above example, if the photon flux density is at most 60 μmol / m ² / s or more as shown in the examples, Although it is considered sufficient, the amount of light can be reduced within a range in which a repellent effect is obtained. For example, the following examples show that the dose can be reduced to about 3.6 μmol / m ² / s at a wavelength of 400 nm and to about 12 μmol / m ² / s at a wavelength of 425 nm.

  Regarding the irradiation time, in the following examples, irradiation is performed for 30 seconds to 5 minutes, but not limited to this, by increasing or decreasing the time within a range in which a repellent effect is obtained, and by performing irradiation intermittently It is thought that power consumption can be saved.

  The termites to be controlled by the method of the present invention are termites belonging to the genus Termite, Yamato Termite, American White Termite, and Daikokite Termite. Among these, the termite genus and the termite genus are mainly effective for irradiation under the floor and the foundation, but it is considered that irradiation for other invasion routes is also effective. As for the American genus termite genus and daikoku termite genus, it is effective to irradiate each part of the structural member including the attic etc. Irradiation to other intrusion routes is also considered effective.

(Test method)
Individuals collected from the nests of termites (Coptotermes formosanus Shiraki) bred at the Forest Research Institute were acclimated to the experimental conditions for one day and immediately subjected to a light irradiation test. For the light irradiation test, the transparent glass container 1 (width 60 × depth 100 × height 26 mm) shown in Fig. 1 is used, and a hole of 26 mm height × 20 mm width is drilled on the short side, and quartz glass 3 is attached. A light inlet was installed. Black drawing paper 2 was laid at the bottom of the container.

  After leaving this container in a dark room with a temperature of 23 ± 3 ° C and relative humidity of 65 ± 5% RH for at least 10 minutes, put 150 termite ants and 15 soldier ants into the container, and leave for another 5 minutes. And termites were adapted to the dark. Then, the light monochromatized under the following conditions was irradiated to the termites in the container in the dark room so that half the area of the container was irradiated as shown in FIG.

Hypermonolite (SM-25 Model made by Spectrometer Co., Ltd.) is used as the light source for light irradiation. The wavelength band is 25 nm from the ultraviolet range of 350 nm to the visible range of 650 nm, and the wavelength interval is 50 nm or 100 nm. Spectroscopic. In order to make the photon quantity at each wavelength constant, the photon flux density (unit area / number of photon moles per unit time) on the vertical axis of the optical axis is 60 μmol / m at the photon flux density measurement point (1) in FIG. ^The light was adjusted in advance using the ND filter 4 so as to be ² / s.

  After 30, 120, and 300 seconds from the start of light irradiation, termites were photographed from the top of the container using a digital camera, and the number of termites present in the range irradiated with light was counted based on the photographed images. The number of repetitions in each test section was 3. After the light irradiation, in order to adjust the termites to the light place, they were allowed to stand for 5 minutes or more under the daytime fluorescent lamp lighting, and further adjusted to the dark place for 5 minutes after the light was turned off.

(Test results)
When the photon flux density at each irradiation wavelength is kept constant (60 μmol / m ² / s), the percentage of the termite individuals that existed in the range irradiated with light (average value. Are shown in Table 1 and FIG.

  When irradiating visible light with a wavelength of 550 nm or less, the “light place abundance” of craftsmen and soldiers decreases as the wavelength decreases, and at a wavelength of 450 nm or less, the light place abundance ratio is almost 25% or less. (Figure 2). In Table 1, when compared to the case of the irradiation wavelength of 650 nm, the abundance of the bright place when the irradiation wavelength is 550 nm or less is significantly lower (p <0.05) except for some values after 30 seconds of irradiation. Repellent behavior (negative phototaxis) is observed. Furthermore, when the wavelength is 450 nm or less, not only the wavelength 650 nm but also the case where the photopic abundance is significantly lower than the wavelength 550 nm is recognized. This indicates that the negative light mobility of termite ants and soldier ants becomes more pronounced at wavelengths below 450 nm. In all the wavelength regions, there was a tendency that the abundance ratio of the photopic spot decreased with the extension of the irradiation time.

  In Fig. 2, in the case of short-time irradiation (30 seconds), the "light place abundance ratio" by visible light with a wavelength of 400 to 450 nm is lower than that of ultraviolet light with a wavelength of 350 to 375 nm, and a high repellent effect (negative It has been shown to produce phototaxis. This indicates that termites may react more sensitively to visible light having a wavelength of 400 to 450 nm. Therefore, using visible light with a wavelength of 400 nm (purple light) and 425 nm (purple to blue light), the photon flux density is gradually reduced by an ND filter and the termites are irradiated for 30 seconds to determine how strong the light is. We examined whether negative phototacticity was seen up to the light. Table 2 and FIG. 3 show the termite light place abundance ratio (%) 30 seconds after the start of irradiation at different photon flux densities when the wavelength is constant at 400 nm as an average value ± standard deviation. Further, Table 3 and FIG. 4 show the termite light place abundance ratio (%) 30 seconds after the start of irradiation at different photon flux densities when the wavelength is 425 nm constant, as an average value ± standard deviation.

As shown in Table 2 and Fig. 3, at the irradiation wavelength of 400 nm, even if the photon flux density (initial value: 60 μmol / m ² / s) decreases to 3.6 μmol / m ² / s, No significant change was observed (p> 0.05), that is, a high repellent effect (negative phototaxis) was maintained. On the other hand, as shown in Table 3 and Fig. 4, when the photon flux density (initial value: 60 μmol / m ² / s) drops to 12 μmol / m ² / s or less at the wavelength of 425 nm, Increased significantly (p <0.05), and no clear repellent effect (negative phototaxis) was observed. From the above, in order to maintain the repellent effect (negative light mobility) at a wavelength of 425 nm, a photon flux density of 12 μmol / m ² / s or more is necessary, but at a wavelength of 400 nm, 3.6 μmol / m ² It has been clarified that a sufficient effect can be obtained even with a photon flux density of about / s.

  From the above results, it can be seen that when using visible light with a wavelength of 400 to 550 nm, termites that feel light take repelling action, and further, when using visible light with a wavelength of 400 to 450 nm, the effect is particularly high. .

  According to the present invention, termites can be controlled without causing a decrease in strength or discoloration of a housing member such as wood under the floor and without adversely affecting the human body.

1 Styrofoam container 2 Black drawing paper 3 Quartz glass 4 ND filter

Claims (2)

Termite control method characterized by irradiating termites with only visible light of 400 to 550 nm. The termite control method according to claim 1, wherein only visible light having a wavelength of 400 to 450 nm is used.