Method and device for exterminating mite parasitic on honeybee

Abstract

To provide a technology to exterminate mites effectively while suppressing an influence on honeybees.SOLUTION: An extermination device (100) for mites parasitic on honeybees includes: an extermination part (10) having a space where inflow and outflow of carbon dioxide is suppressed for sealing a bee hive (200) including honeybees; and a control part (20) for controlling the concentration of carbon dioxide in the extermination part (10) to 10-15%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and device for exterminating mites that parasitize honeybees. [Background technology]

[0002] Varroa mites, which parasitize honeybees, are the cause of Varroasis, a notifiable infectious disease under the Livestock Infectious Diseases Prevention Law, and are the organisms that require the most attention in beekeeping management. Varroa mites parasitize honeybee prepupae, pupae, and adults, but their reproduction is limited to the covered cells (the covered cells seen during the development of honeybee pupae) where the prepupae and pupae grow. Varroa mites lay eggs in the covered cells, which develop into adults and mate before escaping the cells when the honeybees emerge. Varroa mites not only damage honeybee tissue, but also transmit viruses that can cause honeybee deaths. Severe Varroa mite infestations cause colonies to collapse, so there is a need to develop effective methods to control Varroa mites.

[0003] Traditionally, acaricides have been used to eradicate Varroa mites, and three acaricides are registered and sold as veterinary medicines in Japan. However, continued use of acaricides may lead to resistance and reduce their effectiveness. It is also known that spraying acaricides from outside the honeycomb to kill Varroa mites that breed in the honeycomb is ineffective against the mites inside the honeycomb.

[0004] As an extermination method that does not use acaricides, Patent Document 1 and Non-Patent Document 1 describe a method that uses carbon dioxide gas. Patent Document 1 describes a method of exterminating pests by introducing carbon dioxide gas from the outside in a closed environment. Non-Patent Document 1 also describes that the mortality rate of Varroa mites is increased by exposing them to high-concentration (about 73±5%) carbon dioxide gas for about two months in a low-temperature closed environment that simulates a winter environment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-126271 A [Non-patent literature]

[0006] [Non-Patent Document 1] Onayemi et al., Journal of Economic Entomology, 115(4):1054-1058(2022) Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the methods of Patent Document 1 and Non-Patent Document 1, it is necessary to introduce carbon dioxide gas from outside in a closed environment, and temperature control is required, making the control complicated. In addition, when carbon dioxide gas introduced from outside is used on honeybees, it is necessary to use carbon dioxide gas approved as an animal medicine. Furthermore, in the methods of Patent Document 1 and Non-Patent Document 1, it is necessary to expose honeybees to high concentrations of carbon dioxide gas for a long period of time, which may have an adverse effect on the honeybees.

[0008] One aspect of the present invention has been made to solve the above-mentioned problems, and its object is to realize a technology for effectively exterminating mites while minimizing the impact on honeybees. [Means for solving the problem]

[0009] In order to solve the above problems, one embodiment of the present invention provides a method for exterminating mites that parasitize honeybees, which includes the steps of sealing a hive containing honeybees in a space that prevents the inflow and outflow of carbon dioxide, and controlling the carbon dioxide concentration in the space to be 10% or more and 15% or less.

[0010] An extermination device for mites that parasitize honeybees in one embodiment of the present invention has a space in which the inflow and outflow of carbon dioxide is restricted, and is equipped with an extermination unit for sealing a hive containing honeybees, and a control unit for controlling the carbon dioxide concentration within the extermination unit to be greater than or equal to 10% and less than or equal to 15%. Effect of the Invention

[0011] According to one aspect of the present invention, it is possible to realize a technology for effectively exterminating mites while minimizing the impact on honeybees. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a mite extermination device according to one embodiment of the present invention. [Diagram 2] 4 is a flowchart showing an example of a carbon dioxide concentration control process in the mite extermination device according to one embodiment of the present invention. [Diagram 3] 1 is a graph showing the results of an investigation into the change in carbon dioxide concentration due to differences in the number of bee colonies in a carbon dioxide bag in an example. [Figure 4] 1 is a graph showing the results of investigating the effect of exterminating mites by exposure to carbon dioxide gas in an example. [Diagram 5] 1 is a graph showing the results of an investigation into the effect of carbon dioxide concentration on honeybees in an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention relates to a method for exterminating mites that parasitize honeybees (hereinafter, extermination method) and an extermination device for mites that parasitize honeybees (hereinafter, extermination device). Mites that parasitize honeybees are a cause of infectious diseases in honeybees, and therefore need to be exterminated appropriately. On the other hand, some methods for exterminating mites may affect the growth of honeybees. The inventors have found an extermination method that can exterminate mites while minimizing the impact on the growth of honeybees and keeping the honeybees alive, and have completed the present invention.

[0014] In one embodiment of the present invention, the honeybee is intended to be Apis mellifera or Apis japonica, and may be Apis mellifera in particular. In another embodiment of the present invention, the honeybee may be a colony of bees present in a hive. A colony of bees is a bee colony including a queen, brood (larvae and pupae), and worker bees, and one colony of bees is, for example, composed of several thousand to several tens of thousands of bees. In another embodiment of the present invention, the mites to be exterminated are mites that parasitize honeybees, and an example of such a mite is Varroa destructor. In another embodiment of the present invention, the mites to be exterminated are intended to be adult or immature mites, and particularly immature mites.

[0015] The extermination method according to one aspect of the present invention includes a step of sealing a hive containing bees in a space in which the inflow and outflow of carbon dioxide gas is suppressed, and a step of controlling the carbon dioxide concentration in the space to 10% or more and 15% or less. The extermination device according to one aspect of the present invention has a space in which the inflow and outflow of carbon dioxide gas is suppressed, and is equipped with an extermination unit for sealing a hive containing bees, and a control unit for controlling the carbon dioxide concentration in the extermination unit to 10% or more and 15% or less. That is, the extermination method according to one aspect of the present invention can be executed by the extermination device according to one aspect of the present invention. Therefore, in this embodiment, the extermination method according to one aspect of the present invention executed by the extermination device according to one aspect of the present invention will be described.

[0016] Fig. 1 is a schematic diagram illustrating an example of a mite extermination device 100 according to one embodiment of the present invention. As shown in Fig. 1, the mite extermination device 100 includes an extermination unit 10 and a control unit 20. A nest box 200 from which mites are to be exterminated is sealed inside the extermination unit 10. The mite extermination device 100 also includes a circulation unit 30 provided inside the extermination unit 10, and a carbon dioxide concentration detection unit 40 and an outside air introduction unit 50 connected to the extermination unit 10.

[0017] In the extermination method according to one embodiment of the present invention, first, a hive 200 containing honeybees is placed in the extermination unit 10, and the extermination unit 10 is closed to seal the hive 200 in the extermination unit 10 (sealing step). Honeybees capable of spontaneous breathing are contained in the hive 200. The hive entrance of the hive 200 is closed to prevent the bees from entering or leaving.

[0018] The extermination unit 10 has a space in which the inflow and outflow of carbon dioxide gas is suppressed, and the hive 200 is placed and sealed in the space. The extermination unit 10 may be, for example, a bag-shaped body formed from a sheet that suppresses the permeation of carbon dioxide gas, and may be formed by covering the periphery of the hive 200 with such a sheet. In other words, the space of the extermination unit 10 is the space inside the bag-shaped body in which the permeation of carbon dioxide gas is suppressed. The sheet that suppresses the permeation of carbon dioxide gas is, for example, a gas barrier sheet that does not allow carbon dioxide gas to pass through, and is commercially available.

[0019] Since the space within the extermination unit 10 is inhibited from transmitting carbon dioxide gas, when the hive 200 is sealed within the space, carbon dioxide generated by spontaneous respiration of the bees within the hive 200 accumulates, increasing the carbon dioxide concentration within the extermination unit 10. Since the gas within the extermination unit 10 is circulated by the circulation unit 30, the carbon dioxide concentration within the extermination unit 10 becomes uniform. As an example, the circulation unit 30 is a fan that operates at all times. It is not necessary to particularly control the temperature within the extermination unit 10, and it is sufficient if the temperature is such that the bees can grow, and as an example, it is room temperature.

[0020] The control unit 20 controls the carbon dioxide concentration in the extermination unit 10 to be 10% or more and 15% or less (controlling step). After sealing the hive in the extermination unit 10, the carbon dioxide concentration is increased to 10% or more and 15% or less by the spontaneous respiration of the bees. When the carbon dioxide concentration in the extermination unit 10 reaches 10% or more and 15% or less, the control unit 20 controls the carbon dioxide concentration to be 10% or more and 15% or less by replacing a portion of the carbon dioxide gas in the space of the extermination unit 10 with air outside the space.

[0021] The control process of the carbon dioxide concentration by the control unit 20 will be described with reference to Fig. 2. Fig. 2 is a flow chart showing an example of the control process of the carbon dioxide concentration in the mite extermination device 100. First, the control unit 20 acquires the carbon dioxide concentration in the extermination unit 10 by the carbon dioxide concentration detection unit 40 (step S1). The control unit 20 controls the driving of the outside air introduction unit 50 based on the carbon dioxide concentration in the extermination unit 10. The outside air introduction unit 50 is, for example, a pump for introducing outside air.

[0022] The control unit 20 determines whether the carbon dioxide concentration inside the extermination unit 10 exceeds 15% (step S2), and if it does (Yes), it drives the pump of the outside air introduction unit 50 (step S3) to take in outside air into the extermination unit 10. This replaces part of the carbon dioxide gas inside the space of the extermination unit 10 with the air outside the space. If the carbon dioxide concentration does not exceed 15% (No) in step S2, the process ends. The control unit 20 constantly monitors the carbon dioxide concentration and executes the control process.

[0023] Then, the control unit 20 obtains the carbon dioxide concentration in the extermination unit 10 by the carbon dioxide concentration detection unit 40 (step S4), determines whether it is 15% or less (step S5), and if it is 15% or less (Yes), stops the pump of the outside air introduction unit 50 (step S6) and ends the process. If the carbon dioxide concentration is not 15% or less (No) in step S5, the process returns to step S3 and continues to take in outside air. In this way, the control unit 20 controls the carbon dioxide concentration in the extermination unit 10 to be 10% or more and 15% or less.

[0024] In this way, the control unit 20 controls the carbon dioxide concentration by replacing a portion of the carbon dioxide gas in the space of the extermination unit 10 with the air outside the space. In other words, the carbon dioxide concentration in the space of the extermination unit 10 is increased by accumulating carbon dioxide generated by the spontaneous respiration of the honeybees in the extermination unit 10, and there is no need to introduce carbon dioxide from outside. Therefore, there is no need to use carbon dioxide gas approved as an animal medicine. The control unit 20 can control the carbon dioxide concentration simply by replacing a portion of the carbon dioxide gas in the space of the extermination unit 10 with the air outside the space, making control easy.

[0025] It is preferable that the period until the carbon dioxide concentration in the extermination unit 10 reaches 10% or more and 15% or less is short, for example, within 24 hours. The amount of increase in the carbon dioxide concentration in the extermination unit 10 can be adjusted by the volume of the space in the extermination unit 10 and the number of bee colonies sealed in the extermination unit 10. Therefore, the volume of the space in the extermination unit 10 and the number of bee colonies sealed in the extermination unit 10 are adjusted so that the carbon dioxide concentration reaches 10% or more and 15% or less within 24 hours after the hive 200 is sealed. In other words, the hive 200 may contain one or more colonies of bees.

[0026] The control unit 20 controls the carbon dioxide concentration in the extermination unit 10 to be 10% or more and 15% or less for a period of 20 hours or more and 80 hours or less after the carbon dioxide concentration in the extermination unit 10 reaches 10% or more and 15% or less. As a result, the hive 200 is exposed to carbon dioxide gas at a carbon dioxide concentration of 10% or more and 15% or less for a period of 20 hours or more and 80 hours or less.

[0027] By exposing the hive 200 to carbon dioxide gas for 20 hours or more, the proliferation of mites in the hive 200 is suppressed, and the mites can be exterminated. Furthermore, by exposing the hive 200 to carbon dioxide gas for 80 hours or less, the effect on the growth of the honeybees in the hive 200 is suppressed, and the mites can be exterminated while allowing the honeybees to survive. The period for exposing the hive 200 to carbon dioxide gas is preferably 24 hours or more and 72 hours or less, more preferably 48 hours or more and 72 hours or less, and even more preferably 72 hours.

[0028] By exposing the hive 200 to carbon dioxide gas with a carbon dioxide concentration of 10% or more, the proliferation of mites in the hive 200 is suppressed, and the mites can be exterminated. Furthermore, by keeping the carbon dioxide concentration of the carbon dioxide gas to which the hive 200 is exposed to 15% or less, the effect on the growth of the honeybees in the hive 200 is suppressed, and the mites can be exterminated while allowing the honeybees to survive. The carbon dioxide concentration of the carbon dioxide gas to which the hive 200 is exposed is preferably 12% or more and 15% or less, and more preferably 15%.

[0029] The control unit 20 may increase the carbon dioxide concentration in the extermination unit 10 by introducing carbon dioxide gas approved as an animal medicine into the extermination unit 10. In this case, carbon dioxide gas is introduced into the extermination unit 10 from an intake port provided in the extermination unit 10. Since the extermination unit 10 is designed to suppress the permeation of carbon dioxide gas, the amount of carbon dioxide gas introduced is kept small. As an example, if the nest box 200 is exposed to carbon dioxide gas for 72 hours, the carbon dioxide concentration decreases by within 1%, so that after the carbon dioxide gas is introduced initially to increase the carbon dioxide concentration, there is no need to introduce additional carbon dioxide gas.

[0030] In the extermination method and extermination device according to one embodiment of the present invention, mites can be exterminated simply by controlling the carbon dioxide concentration in the extermination unit 10 to 12% or more and 15% or less, so temperature control is not required, control is easy, and the treatment time is not limited. In addition, in the extermination method and extermination device according to one embodiment of the present invention, it is not necessary to introduce carbon dioxide gas from the outside, so there is no need to use carbon dioxide gas approved as an animal medicine. Furthermore, in the extermination method and extermination device according to one embodiment of the present invention, there is no need to expose the honeybees to high concentrations of carbon dioxide gas for a long period of time, so there is no impact on the growth of the honeybees. In addition, in the extermination method and extermination device according to one embodiment of the present invention, carbon dioxide gas can pass through the lid of the covered nest chamber, so the reproduction of mites in the pupal nest chamber can be suppressed.

[0031] The above-mentioned configuration leads to the maintenance and development of agriculture. Such an effect also contributes to the achievement of Goal 15 of the Sustainable Development Goals (SDGs) advocated by the United Nations, "Protect and sustain the life on land."

[0032] [Additional Note 1] The present invention can also be expressed as follows.

[0033] A method for exterminating mites that parasitize honeybees according to aspect 1 of the present invention includes the steps of sealing a hive containing honeybees in a space in which the inflow and outflow of carbon dioxide is restricted, and controlling the carbon dioxide concentration in the space to 10% or more and 15% or less.

[0034] In the method for exterminating mites that parasitize honeybees according to aspect 2 of the present invention, in the controlling step, the carbon dioxide concentration may be controlled by replacing a portion of the carbon dioxide gas in the space with air outside the space.

[0035] The method for exterminating mites parasitic on honeybees according to aspect 3 of the present invention, in accordance with aspect 1 or 2, may further comprise controlling the carbon dioxide concentration for a period of 20 hours or more and 80 hours or less in the controlling step.

[0036] A method for exterminating mites that parasitize honeybees according to a fourth aspect of the present invention is any one of the first to third aspects, wherein the space is an internal space of a bag-like body in which carbon dioxide permeation is inhibited.

[0037] A fifth aspect of the present invention relates to a method for exterminating mites parasitic on honeybees, in any one of the first to fourth aspects, wherein the hive may contain one or more groups of honeybees.

[0038] The extermination device for mites that parasitize honeybees according to aspect 6 of the present invention has a space in which the inflow and outflow of carbon dioxide is restricted, and is equipped with an extermination unit for sealing a hive containing honeybees, and a control unit for controlling the carbon dioxide concentration within the extermination unit to be not less than 10% and not more than 15%.

[0039] [Additional Note 2] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. EXAMPLES

[0040] A method for exterminating mites that parasitize honeybees was investigated. A hive containing a honeybee queen, brood (larvae and pupae), and a colony including worker bees was sealed in a carbon dioxide bag (external dimensions W0.8m x D1.5m x H1m, manufactured by Nippon Ekitan Co., Ltd.). A gas concentration detector, carbon dioxide concentration regulator, and a pump for introducing outside air were connected to the carbon dioxide bag, and an air circulation fan (operating constantly) was installed inside the carbon dioxide bag. The entrance to the hive was closed to prevent the bees from entering or leaving.

[0041] The number of days it took for the carbon dioxide concentration to rise to 15% after the hive was sealed in the carbon dioxide bag was confirmed. The change in carbon dioxide concentration was confirmed for the cases where one colony of bees was sealed in the carbon dioxide bag and where three colonies of bees were sealed in the carbon dioxide bag, without introducing carbon dioxide from outside. The results are shown in Figure 3. Figure 3 is a graph showing the results of measuring the change in carbon dioxide concentration inside the carbon dioxide bag.

[0042] As shown in Figure 3, the number of days it took for the carbon dioxide concentration to rise to 15% in a carbon dioxide bag with external dimensions of W0.8m x D1.5m x H1m was approximately 1.5 days when one colony of honeybees was introduced, but within one day when three colonies were introduced. Since the carbon dioxide concentration in the carbon dioxide bag is affected by the volume of the carbon dioxide bag and the number of bee colonies introduced, the number of bee colonies that will reach a carbon dioxide concentration of 15% within one day of the bees' introduction is introduced into the carbon dioxide bag.

[0043] In this example, three groups of bees were introduced into a carbon dioxide bag with external dimensions of W0.8m×D1.5m×H1m, and the carbon dioxide concentration was increased to 15% within one day. After that, the upper limit of the carbon dioxide concentration regulator was set to 15%, and when the carbon dioxide concentration increased above 15%, the carbon dioxide concentration in the carbon dioxide bag was controlled by a method of taking in outside air to reduce the gas concentration. After exposing the bees in the carbon dioxide bag to carbon dioxide for three days, the hive was removed from the carbon dioxide bag and placed outdoors, and the hive entrance was opened. As a control, three groups of bees that were not exposed to carbon dioxide were used.

[0044] The mite infestation rate was examined in the bee colonies of the example and the control. The results are shown in Figure 4. Figure 4 is a graph showing the results of examining the effect of exterminating mites by exposure to carbon dioxide gas in the example.

[0045] As shown in Figure 4, the honeybees exposed to carbon dioxide had a significantly lower rate of operculate brood parasitism than the control, and no nymphal mites were detected. Thus, it was shown that treatment with 15% carbon dioxide for three days significantly reduced the rate of mite parasitism and made it possible to eradicate mites.

[0046] Next, the effect of carbon dioxide gas treatment on honeybees was examined. The average mortality rate was calculated for adult honeybees treated with carbon dioxide gas at a concentration of 15% or 18% for three days, and for adult honeybees not exposed to carbon dioxide gas. The results are shown in Figure 5. Figure 5 is a graph showing the results of an investigation into the effect of carbon dioxide gas concentration on honeybees in the examples.

[0047] As shown in Figure 5, the average mortality rate of honeybees treated with 18% carbon dioxide for three days was higher than that of the control and honeybees treated with 18% carbon dioxide for three days. Thus, in order to obtain mite extermination effects while minimizing the impact on honeybee growth, treatment with a carbon dioxide concentration of 15% or less was suitable. [Industrial Applicability]

[0048] The present invention can be utilized in the agricultural field by being applied to beekeeping, breeding of honeybees for mating, and the like. [Explanation of symbols]

[0049] 10. Extermination Department 20 Control section 100 Extermination Device 200 Hive

Claims

1. A method for exterminating mites that parasitize honeybees, comprising the steps of: A process of sealing a hive containing bees in a space in which the inflow and outflow of carbon dioxide gas is restricted; A step of controlling the carbon dioxide concentration in the space to 10% or more and 15% or less; The method for exterminating mites that parasitize honeybees comprises the steps of:

2. 2. The method for exterminating mites that parasitize honeybees as described in claim 1, wherein the carbon dioxide concentration is controlled by replacing a portion of the carbon dioxide gas in the space with air outside the space in the controlling step.

3. 3. The method for exterminating mites that parasitize honeybees according to claim 1 or 2, wherein in the controlling step, the carbon dioxide concentration is controlled for a period of 20 hours or more and 80 hours or less.

4. 3. The method for exterminating mites that parasitize honeybees according to claim 1 or 2, wherein the space is an internal space of a bag-like body in which carbon dioxide permeation is inhibited.

5. 3. The method for exterminating mites that parasitize honeybees according to claim 1 or 2, wherein the hive contains one or more colonies of honeybees.

6. A device for exterminating mites that parasitize honeybees, comprising: An extermination unit for sealing a hive containing bees, the extermination unit having a space in which the inflow and outflow of carbon dioxide is suppressed; A control unit that controls the carbon dioxide concentration in the extermination unit to 10% or more and 15% or less; The device for exterminating mites that parasitize honeybees is provided.

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