METHOD AND DEVICE FOR EXTERMINATING ARTHROPODS

Abstract

Method for exterminating arthropods comprising the steps of providing inside an adiabatic chamber (1) the following elements: at least one blowing heater (2, 21, 22), at least one steam production device (5), and at least one object to be treated (4), operating said at least one blowing heater (2, 21, 22) until a lethal temperature sufficient for the arthropods is reached, characterized in that following step b. the method further comprises operating the at least one steam production device (5), stopping the treatment.

Description

Title of the invention: METHOD AND DEVICE FOR EXTERMINATING ARTHROPODS

[0001] The present invention relates to a method for exterminating arthropods, preferably bedbugs, in an adiabatic chamber, by combining heat treatment and steam treatment.

[0002] Professional extermination of arthropods, particularly bedbugs, without using chemicals, generally uses either dry steam generators or adiabatic chambers subjected to heat treatment.

[0003] So-called dry steam generators are a localized treatment of infested objects which, to be effective, requires careful treatment of all the surfaces to be treated.

[0004] The latent heat contained in the steam is released when the steam condenses to become liquid. The amount of latent heat is 2 to 5 times greater than the amount of sensible heat contained in hot water after condensation. These steam generator systems are therefore very effective at short distances in treating infested objects.

[0005] However, each of the infected areas must be subjected to treatment for a sufficient time for the latent heat of the steam to be effectively transmitted to the insects and eggs. This treatment is therefore a fortiori very long to implement, especially if many objects, or even all the risk objects in a building, are infested.

[0006] Existing devices using an adiabatic chamber in which the objects to be treated are arranged require high-power, high-amperage blower heaters. These professional heaters are electrically powered by systems outside the building to be treated, generally by trucks equipped with an independent power supply.

[0007] Installing electrical cables from the outside of the building to each of the rooms to be treated is therefore a tedious and time-consuming task, significantly increasing treatment costs.

[0008] Furthermore, in real conditions, obtaining a relatively homogeneous temperature throughout the adiabatic chamber in the presence of objects to be treated, taking into account their thermal conduction, at least higher than the lethal temperature required for arthropods, requires a treatment time much higher than the literature in laboratory conditions in small ovens and especially without a large object to be treated.

[0009] To this end, commercially available devices which implement an adiabatic chamber do not appear to communicate recommendations for treatment times for infected objects, which can reach several hours.

[0010] The study by Kells et al. (Insects 2011, 2, 412-422) highlights these issues well, noting that the current temperature range targeted by companies performing heat treatments is 45 to 52 °C; however, there may be locations in the heated area above and below this range. In general, the airspace inside a heat-treated room can approach 55 to 65 °C to ensure efficient heat transfer to the objects being treated. Therefore, the final temperature to which bed bugs will be exposed will depend on the insulating and thermal mass of the heated materials.

[0011] This study also indicates that the previously reported lethal temperature for bed bugs under laboratory conditions was 45°C for eggs and 44°C for adults during a 1-hour exposure (Mellanby, Parasitology 1935, 27, 111-122.), and that this time could be reduced to 1 min at 49°C (Pereira et al., J. Econ. Entomol. 2009, 102, 1182-1188.). However, this threshold was determined by rapid exposure to high temperatures with a rate of temperature increase that is considerably different from the application of heat in a whole-room treatment.

[0012] This study also demonstrates that in laboratory conditions, to exterminate eggs at a temperature of 48°C, it is necessary to apply a heat treatment for 70 minutes, while the immediate death temperature for eggs has been estimated at 54.8°C.

[0013] Thus, the problem in a real situation is to reach a temperature at least equal to 50°C in the whole of an adiabatic chamber of a substantial volume in which objects to be treated are positioned, such as beds, wardrobes, etc., within a reasonable time for obvious problems of cost and treatment time.

[0014] The present invention thus proposes a method and a device combining a heat treatment and a water vapor treatment to overcome the aforementioned drawbacks.

[0015] Thus, the method for exterminating arthropods according to the invention comprises the following steps: a. providing inside an adiabatic chamber the following elements: at least one blowing heater, at least one steam production device, and at least one object to be treated, b. operating said at least one blowing heater until a sufficient lethal temperature for the arthropods is reached, characterized in that following step b. the method further comprises operating the at least one steam production device, stopping the treatment.

[0016] According to one characteristic, at least one humidity sensor is provided inside the adiabatic chamber and in that the operation of the steam production device is carried out until a relative humidity level of between 30 and 60 percent, preferably between 30 and 50 percent, is reached.

[0017] According to an additional characteristic, at least one temperature sensor is provided inside the adiabatic chamber and in that the sufficient lethal temperature to be reached in step b. is between 45 and 65°C, preferably between 50 and 55°C, more preferably 50°C.

[0018] According to one embodiment, the temperature reached in step b. is maintained in step c.

[0019] According to the preceding embodiment, the at least one blower heating device is stopped when the at least one steam production device is put into operation.

[0020] According to an additional characteristic, the power of the at least one blower heater is sized according to the volume of the adiabatic chamber, in such a way that the sufficient lethal temperature is reached in less than 60 minutes, preferably in less than 50 minutes, preferably in less than 40 minutes.

[0021] According to one embodiment, the operation of the steam production device in step c. is carried out for a duration of between 5 and 15 minutes.

[0022] According to the preceding embodiment, the sum of the processing times of steps b. and c. is less than 60 minutes, preferably less than 50 minutes.

[0023] According to one characteristic, the total power of the at least one blower heater has a power of between 2000 and 6000 Watts.

[0024] The invention also relates to an arthropod extermination device capable of implementing the method according to the invention, comprising an adiabatic chamber, a blowing heating device, a temperature sensor, a humidity sensor, a steam production device capable of being put into operation at a temperature lethal for the arthropods.

[0025] The implementation of the invention will be better understood with the aid of the detailed description which is set out below with reference to the appended drawings in which:

[0026] [Fig-1] is a schematic top view of the arthropod extermination device according to the invention.

[0027] [Fig.2] represents a graph representing the measurement of the temperature of four temperature sensors as a function of time, the indicator V represented by an arrow corresponds to the operation of the steam production device.

[0028] [Fig.3] represents a graph representing the measurement of the relative humidity rate of four humidity sensors as a function of time, the indicator V represented by an arrow corresponds to the operation of the steam production device.

[0029] [Fig.4] represents a flowchart illustrating the steps of a method according to the invention.

[0030] [Fig.5] represents a table of Humidex indices as a function of temperature and relative humidity.

[0031] The invention aims to provide a specific device and method for the extermination of arthropods, using the consequences of the Humidex index on living beings, in hot and humid conditions.

[0032] The invention relates more particularly to a device and a specific method for the extermination of bedbugs, i.e., cimex lectularius.

[0033] The humidex index represents the effects that high humidity and warm temperatures can have on the body. The higher the humidex, the more difficult it is for perspiration to evaporate and cool the body. The humidex index combines temperature and humidity into a single number that reflects the perceived temperature (ccohs.ca).

[0034] The humidex index is a formula used by Canadian meteorologists to integrate the combined effects of heat and humidity.

[0035] In other words, the Humidex index is a measure of how hot it feels. The humidex is a dimensionless number, a calculator for which is available on the Occupational Health Clinic for Ontario Workers website (https: / / www.ohcow.on.ca / edit / files / general_handouts / heat-stress-calculator.html).

[0036] As explained in [Fig. 5], and explained in more detail in the remainder of the description, in the temperature and humidity ranges covered by the present invention, the Humidex index increases significantly in comparison with the actual temperature measured.

[0037] As a counter-example, the Humidex index at 20°C and a humidity level of 40% is equal to 20, whereas at a humidity level of 60% the Humidex index is only 22.

[0038] Thus, the method for exterminating arthropods according to the invention comprises a step of heating the interior space of an adiabatic chamber (1) to a temperature between 45 and 60°C.

[0039] Once the temperature in the adiabatic chamber (1) reaches the target range of 45 to 60°C, the relative humidity of the adiabatic chamber (1) is increased by a rate of between 30 and 60%.

[0040] Preferably, the interval targeted during the heating step is between 50 and 55°C, more preferably 50°C.

[0041] In the temperature range between 45 and 60°C at a humidity level of 30%, the Humidex index varies between 55 and 87; at a humidity level of 40%, the Humidex index varies between 61 and 98; at a humidity level of 50%, the Humidex index varies between 66 and 109; at a humidity level of 60%, the Humidex index varies between 71 and 120.

[0042] More precisely at the theoretical lethal temperature for arthropods of 50°C, at a humidity level between 30 and 60%, the Humidex index is between 65 and 85.

[0043] The heat felt in high humidity conditions is thus greater than in dry conditions, hence the expression dying of heat in humid conditions.

[0044] Let us add that insects are poikilothermic organisms or also called heterotherms: the temperature of their body is not stable and varies according to that of the environment (Bligh, J et al, J Appl Physiol, 35(6): 941-961.)

[0045] As a result, arthropods cannot naturally regulate their temperature.

[0046] In order to facilitate heat loss in order to cool the body, some insects can use evaporative cooling (May, 1979). This phenomenon can thus greatly aid survival at high temperatures, but will be much more effective in a dry environment than in a humid one (Prange, 1996). But very often, the internal water reserves of most insects are too small to allow this type of thermal regulation, even when engorged with blood.

[0047] Accordingly, at temperatures close to the lethal temperature, but at high humidity levels, arthropod mortality should be reached more quickly than in a dry environment such as in an adiabatic chamber equipped only with a heating device without a steam generating device.

[0048] Let us recall that an adiabatic chamber is understood to mean a chamber which is impermeable or substantially impermeable to heat. More precisely, the adiabatic chamber comprises so-called adiabatic walls, in that the walls prohibit or prevent the exchange of heat between the interior of the chamber and the exterior.

[0049] As previously introduced, reaching a lethal temperature for arthropods in the entirety of an adiabatic chamber in the presence of an object to be treated, in a reasonable time is a difficult task.

[0050] As introduced previously, in order to overcome this drawback, the invention proposes increasing the humidity level as soon as the theoretical lethal temperature is substantially reached in the adiabatic chamber (1).

[0051] This increase in humidity, increasing the lethal conditions in the adiabatic chamber (1), allows even areas where the temperature has not reached the theoretical lethal temperature to be in lethal conditions for arthropods.

[0052] This combination of high temperature and humidity conditions thus makes it possible to limit the heating time to achieve an overall arthropod mortality rate of a temperature significantly lower than the theoretical lethal temperature, at least in a time shorter than conditions without the addition of water vapor.

[0053] The arthropod extermination device thus comprises an adiabatic chamber (1), at least one blowing heating device (2, 21, 22), at least one steam production device (5).

[0054] A steam production device is understood to mean a device for producing so-called dry water vapor, i.e. saturated at the nozzle outlet.

[0055] According to one characteristic, the adiabatic chamber (1) has a volume of between 4 and 8 m3.

[0056] According to another characteristic, the total power of the at least one blower heater (2) has a power of between 2000 and 6000 Watts.

[0057] According to the preceding characteristic, the at least one blower heater (2) used in the present invention is capable of being connected to the domestic electrical network of the homes to be treated.

[0058] According to one embodiment, the arthropod extermination device comprises at least two blower heaters (2, 21, 22) whose total operating power is between 2000 and 6000 W.

[0059] According to the embodiment illustrated in [Fig.l], the arthropod extermination device comprises three blower heaters (2, 21, 22) whose total operating power is between 2000 and 6000 W.

[0060] It is understood by a blowing heating device (2, 21, 22), a heating device in which a preferably pulsed ventilation system is integrated, or a heating device combined with a fan.

[0061] More specifically, according to the embodiment illustrated in [Fig.l], the at least one blowing heater (2) comprises a first blowing heater (21) of 3000 W and two second blowing heaters (22) each set to a power of 1000 W.

[0062] According to the preceding embodiment, the two second blower heaters (22) each set to a power of 1000 W are devices having a power of 2000 W each.

[0063] It should be noted that the second heating devices (22) are preferably oriented differently from each other, so that their blower operates in different directions.

[0064] It should also be noted that the at least one second blowing heater (22) is preferably arranged opposite the first blowing heater (21), preferably each arranged at the ends of the interior space of the adiabatic chamber (1), the at least one object (4) to be treated being positioned substantially in the center of the adiabatic chamber (1).

[0065] An adiabatic chamber (1) generally having a rectangular base, the blowing heaters (2) being positioned opposite each other along the length of the rectangular base, as illustrated in [Fig.l].

[0066] According to the arrangement example illustrated in [Fig.l], the first blower heater (21) being positioned in one corner of the adiabatic chamber (1), while the second blower heaters (22) are arranged at the opposite corner.

[0067] According to another embodiment, the at least one blower heater comprises a first blower heater (21) of 3000 W and a second blower heater (22) having a power of 3000 W set to a power of 2000 W.

[0068] According to an additional characteristic, the first blowing heater (21) is arranged at the floor level of the adiabatic chamber (1), while the at least one second blowing heater (22) is raised above the floor, for example at a distance corresponding to half the height of the adiabatic chamber (1), for example at a height of 1 meter above the floor.

[0069] The steam production device (5) is capable of rapidly increasing the relative humidity level in the adiabatic chamber (1).

[0070] For this purpose, according to an additional characteristic, the steam production device (5) preferably has a power of between 1500 and 3000 W, preferably between 2000 and 2500 W.

[0071] Furthermore, according to embodiments, the arthropod extermination device also comprises at least one temperature sensor (3) and advantageously a relative humidity sensor (3).

[0072] According to the embodiment illustrated in [Fig.l], the arthropod extermination device comprises at least one sensor capable of measuring both temperature and relative humidity.

[0073] According to the embodiment illustrated in [Fig.l], the adiabatic chamber (1) has a dimension of 240x120x200 centimeters (length, width, height), i.e. a volume of approximately 5.8 m3.

[0074] The first blowing heater (21) is arranged on the ground, the two second blowing heat devices (22) are positioned at a height approximately 1 m from the ground, the second heat producing devices (22) being installed opposite the first blowing heat device (21).

[0075] The adiabatic chamber (1) is equipped with five temperature and relative humidity sensors (3), the sensors (3) used being capable of measuring both temperature and relative humidity.

[0076] The adiabatic chamber (1) illustrated in this example thus comprises a first sensor (31), a second sensor (32), a third sensor (33), a fourth sensor (34) and a fifth sensor (35).

[0077] The first sensor (31) being positioned on the ground behind the first blower heater device (21), this sensor has the role of controlling the risk of overheating of the first device, the measurements of which are not indicated in the graphs of figures 2 and 3.

[0078] The second sensor (32) and the fourth sensor (34) are positioned on the ground, the fifth sensor (35) is arranged at a height substantially at the upper end of the adiabatic chamber (1) above the two second blower heaters (22), and the third sensor (33) being arranged on the bed.

[0079] The sensors (3) are connected to a measuring unit and to a computer, capable of carrying out data acquisition.

[0080] According to one embodiment, the at least one blower heater (2) and the steam production device (5) are controlled by the computer, making it possible to regulate their operation according to the temperature and relative humidity measurements, as a function of predetermined parameters.

[0081] According to the present invention and as introduced previously, the set temperature is between 45 and 60°C, once the set temperature is reached the relative humidity level set point is adjusted to a rate between 30 and 60%.

[0082] According to a preferred embodiment, the at least one heating device (2) is stopped when the steam device (5) is put into operation, the temperature being maintained inside the adiabatic chamber (1) by the heat input from the latent steam.

[0083] Figures 2 and 3 thus represent graphs of the measurements of the temperature and the relative humidity level respectively, and were carried out during the same treatment cycle according to the method of the invention.

[0084] In this example, a first 3000 W blower heater (21) set to maximum power and two second 2000 W blower heaters (22) set to 50% power, as well as a steam production device (5) with a power of 2250 W, were used.

[0085] A bed and a box spring as an object (4) to be treated, with a dimension of 140 by 190 centimeters were positioned relatively to the center of the adiabatic chamber (1), between the blowing heaters (2, 21, 22).

[0086] For this example, a set of bedbugs were placed on a self-adhesive film positioned on the upper face of the bed.

[0087] It was considered that the theoretical lethal temperature is reached when the third sensor (33) placed on the bed measures the temperature of 50°C.

[0088] More specifically, the measurements shown in the graphs of Figures 2 and 3 illustrate the following chronology: heating of the first and second blowing heat devices (21, 22) for approximately 34 minutes, the temperature of the third sensor (33) having reached the lethal temperature of 50°C, stopping of the first and second blowing heat devices (22), starting of the steam device (5) (illustrated by the arrow and the letter V in the graphs of Figures 2 and 3), after 34 minutes at the temperature of 50°C measured by the third sensor (33) this same sensor measures a humidity level of 20%, stopping of the treatment after 47 minutes, at the stopping of the treatment the third sensor (33) displays a humidity level of approximately 45% and a temperature of approximately 53°C.

[0089] Note that after 34 minutes of treatment the second, fourth and fifth sensors (32, 34, 35) measure temperatures between approximately 55 and 60°C and relative humidity levels between 10 and 15%.

[0090] Let us also add that at the end of the treatment the second, fourth and fifth sensors (32, 34, 35) measure relative humidity levels between approximately 40 and 60%.

[0091] The entire population of the bed bug sample was eradicated at the end of the treatment.

[0092] The method according to the invention thus allows for bedbug eradication treatment, effective in less than an hour.

[0093] The method also makes it possible to achieve an effective eradication treatment by considering a limited operating time of the at least one heating device (2), limiting the cost of the treatment.

[0094] It is understood that for repeated treatments of equivalent infested objects, of which a treatment has been carried out in the presence of at least one temperature sensor (3) and at least one humidity sensor (3), the installation of temperature and humidity sensors (3) at each of the treatment cycles is not necessarily necessary, as long as the protocol adapted for the extermination of arthropods is rigorously followed.

[0095] For this purpose, as represented by the flowchart of [Fig.4], the method for implementing the invention comprises the steps of heating the steam production device (5), installing the adiabatic chamber (1), stopping the steam production device (5), starting the first blower heater (21), starting the two second blower heaters (22) at a power of 50%, heating the adiabatic chamber (1) until the theoretical lethal temperature of 50°C is reached, advantageously stopping the first and second blower heaters (22), reheating the steam production device (5), starting the steam production device (5), end of the treatment.

[0096] According to an optimized example of the invention, the arthropod extermination device comprises a first blower heater (21) of 3000 W and two second blower heaters (22) preferably of 2000 W set during heating to a power of 1000 W each.

[0097] The blowing heating devices (2, 2122) are switched off as soon as the theoretical lethal temperature is reached, the steam production device (5) being sufficient to maintain the target temperature in the adiabatic chamber (1) during the steam production phase.

[0098] As introduced previously, the steam production step in the adiabatic chamber (1) is started as soon as the theoretical lethal temperature is reached.

[0099] Indeed, preliminary tests in which the steam production device (5) was started at the start of the treatment, at the end of the treatment the steam had condensed on the entirety of the walls of the adiabatic chamber (1) and the various objects to be treated, as well as on the blowing heating devices (2). Such final conditions, in which the objects are soaked, are not conceivable.

[0100] The specificity of the method according to the invention, in which the production of steam is carried out for a determined time, when the theoretical lethal temperature is reached, makes it possible to reasonably limit the phenomena of condensation of the steam on the objects present in the adiabatic chamber (1).

[0101] A sufficient lethal temperature for arthropods is understood to mean a theoretical lethal temperature at which the arthropods have a theoretical mortality rate of 100% within a reasonable time, namely within a treatment time of less than 7 hours, preferably less than 2 hours, preferably less than 1 hour, preferably less than 30 min, preferably less than 1 minute.

[0102] Consequently, a sufficient lethal temperature for arthropods is understood to mean a temperature above 45°C, preferably above 48°C, preferably equal to 50°C, advantageously above 50°C while remaining below 65°C, preferably below 60°C, more preferably below 55°C.

[0103] According to one embodiment, the sufficient lethal temperature of the arthropods in step b. is greater than or equal to 45°C, the humidity level to be reached in step c. being between 30 and 60°C.

[0104] According to the previous embodiment, the Humidex index is between 55 and 71.

[0105] According to another embodiment, the sufficient lethal temperature of the arthropods in step b. is greater than or equal to 48°C, the humidity level to be reached in step c. being between 30 and 60°C.

[0106] According to the preceding embodiment, the Humidex index at 48°C is between 61 and 79.

[0107] According to one embodiment, the sufficient lethal temperature of the arthropods in step b. is greater than or equal to 50°C, the humidity level to be reached in step c. being between 30 and 60°C.

[0108] According to the preceding embodiment and as previously introduced, the Humidex index at 50°C is between 65 and 85.

[0109] According to another embodiment, the sufficient lethal temperature of the arthropods in step b. is equal to 50°C, the humidity level to be reached in step c. being between 30 and 60°C.

[0110] According to one embodiment, the sufficient lethal temperature of the arthropods in step b. is between 50 and 65°C, preferably between 50 and 60°C, preferably between 50 and 55°C, the humidity level to be reached in step c. being between 30 and 60°C.

[0111] According to the preceding embodiment, the Humidex index at 55°C is between 75 and 101.

[0112] According to the preceding embodiment, the Humidex index at 60°C is between 87 and 120.

[0113] According to the preceding embodiment, the Humidex index at 65°C is between 101 and 142.

[0114] According to an additional characteristic, the adiabatic chamber is removable.

[0115] The arthropod eradication device according to the invention thus allows it to be electrically powered by the domestic electrical network of a home and the effective treatment of infected objects in less than one hour. This treatment time does not include the installation of the adiabatic chamber in the place to be treated.

Claims

Claims

1. A method for exterminating arthropods comprising the following steps: a. Providing inside an adiabatic chamber (1) the following elements: i. at least one blowing heater (2, 21, 22), ii. at least one steam generating device (5), and iii. at least one object to be treated (4), b. Operating said at least one blowing heater (2, 21, 22) until a lethal temperature sufficient for the arthropods is reached, c. Characterized in that following step b. the method further comprises operating the at least one steam generating device (5), d. Stopping the treatment.

2. Method according to claim 1, characterized in that at least one humidity sensor (3) is provided inside the adiabatic chamber (1) and in that the operation of the steam production device (5) is carried out until a relative humidity level of between 30 and 60 percent, preferably between 30 and 50 percent, is reached.

3. Method according to claim 1 or 2, characterized in that at least one temperature sensor (3) is provided inside the adiabatic chamber (1) and in that the sufficient lethal temperature to be reached in step b. is between 45 and 65°C, preferably between 50 and 55°C, more preferably 50°C.

4. Method according to any one of the preceding claims, characterized in that the temperature reached in step b. is maintained in step c.

5. Method according to the preceding claim, characterized in that the at least one blower heater (2, 21, 22) is stopped when the at least one steam production device (5) is put into operation.

6. Method according to any one of the preceding claims, characterized in that the power of the at least one device of blower heater (2, 21, 22) is dimensioned according to the volume of the adiabatic chamber (1), in such a way that the sufficient lethal temperature is reached in less than 60 minutes, preferably in less than 50 minutes, preferably in less than 40 minutes.

7. Method according to any one of the preceding claims, characterized in that the operation of the steam production device (5) in step c. is carried out for a duration of between 5 and 15 minutes.

8. Method according to any one of the preceding claims, characterized in that the sum of the treatment times of steps b. and c. is less than 60 minutes, preferably less than 50 minutes.

9. Method according to any one of the preceding claims, characterized in that the total power of the at least one blower heater (2, 21, 22) has a power of between 2000 and 6000 Watt.

10. Arthropod extermination device capable of implementing the method according to one of claims 1 to 9, comprising an adiabatic chamber (1), a blowing heating device (2, 21, 22), a temperature sensor (3), a humidity sensor (3), a steam production device (5) capable of being put into operation at a temperature lethal for arthropods.

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