Abstract
The present invention describes a method and associated equipment for using irradiated, magnetic energy (6) to carry out pest control in plants and vegetable matter e.g. agricultural crops and vegetable foodstuffs. The invention is also suitable for pest control in woody materials and is useful for any material, which is reasonably transparent to B-field energy, to attack a pest (1) that is more opaque to B-field energy than the substrate on or within which the pest (1) is located, such as wasps inside a wall cavity, or slugs and snails under the soil, or mosquito larvae in water.
Claims
1-12. (canceled)
13. A method of pest control, the method comprising the steps of: using irradiated energy of a sufficient strength to destroy or incapacitate a pest, whilst leaving a substrate plant or woody material unaffected, wherein the irradiated energy comprises a magnetic field of optimized frequency, intensity and duration.
14. The method of claim 13, wherein the magnetic field is sufficient to provide magnetic induction heating of part or all of the pest, while leaving the substrate material unaffected.
15. The method of claim 14, wherein the magnetic field is sufficient to provide radio frequency magnetic induction heating.
16. The method of claim 13, wherein the magnetic field has a frequency of 0-1 GHz.
17. The method of claim 13, wherein the magnetic field has a frequency of frequency of 1 MHz-400 MHz.
18. The method of claim 13, wherein the magnetic field strength is 0-100 T, preferably millitesla up to tens of millitesla.
19. An apparatus for pest control comprising: a high-frequency magnetic field generator connected to an electrical power supply.
20. The apparatus of claim 19, wherein the magnetic field generator further comprises at least one nozzle.
21. The apparatus of claim 19, wherein the apparatus includes a propulsion device adapted to direct a magnetic field onto a section of a substrate material.
22. The apparatus of claim 19, wherein the apparatus includes a magnetic lens to focus the magnetic field onto a kill zone containing a pest.
23. The apparatus of claim 19, wherein the apparatus shields against electromagnetic noise.
24. The apparatus of claim 19, wherein the magnetic field generator is shut down if the inductance is not what is expected.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0077] The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:
[0078] FIG. 1 shows the electrical conductivity of animal material, which can be seen to be generally above 0.1 S/m. However, plant material generally has a conductivity an order or magnitude or two lower, and cannot be seen on the graph at this scale.;
[0079] FIG. 2 shows the electrical resistivity (the inverse of electrical conductivity), and the values for plant material can now be seen with respect to those of animal material;
[0080] FIG. 3 shows a graph of the variation between magnetic flux density (mT) with the magnetic field frequency (mHz) as a guide to quantitative B-field energy required to kill certain invertebrates:
[0081] FIG. 4 shows (simply) how magnetic induction heating for pest control (MIHPC) allows a magnetic field to be directed and targeted on a pest;
[0082] FIG. 5 shows the MIHPC device according to the invention, mounted on a tractor for agricultural crop use;
[0083] FIG. 6 shows the MIHPC device according to the invention, being used on a motorised trolley or suchlike for horticultural use;
[0084] FIG. 7 shows the MIHPC device according to the invention, incorporated into a hand-held can, such as an aerosol spray can;
[0085] FIG. 8 shows the MIHPC device according to the invention, incorporated into an overhead gantry, such as that used in the food packaging industry; and finally
[0086] FIG. 9 shows the MIHPC device according to the invention, incorporated into a grain flow pipe or similar, commonly used in grain harvesters, grain silos and for grain shipping.
[0087] Referring to the graph shown in FIG. 1, the electrical conductivity of animal material is generally an order of magnitude or two higher than that of plant material. Salt water, 0.5% by mass, has an electrical conductivity of about 0.8 S/m, similar to that of animal material. (For comparison, seawater has around 3.5% salt by mass, and thus a higher electrical conductivity of about 4 S/m.)
[0088] FIG. 2 shows the converse of this relationship, and thus by comparison of FIGS. 1 and 2, the electrical conductivity of animal material can be seen in the former, whereas the electrical resistivity of plant material is apparent in the latter.
[0089] With reference to FIG. 3, it is currently thought that a magnetic flux density B=25 mT oscillating at a frequency f=27 MHz will deliver sufficient B-field inductive heating to kill a slug in one second, yet leave a lettuce unheated. Absorbed power p B.sup.2 f.sup.2 for any given sample and for a chosen absorbed power, B=constant/f. Therefore, for a field with B=25 mT and f=27 MHz, the respective constant=675 MHz.Math.mT, and the relationship illustrated thus results.
[0090] FIG. 4 is a very simple illustration of the type of equipment needed for application of the MIHPC method of the present invention. A magnetic field generator 5 is specific to each application. The requirement is to generate a given frequency (generally megahertz frequency) at a given magnetic flux density (generally several tens of millitesla) to kill the target 1, but minimise collateral damage to the substrate upon which the target 1 lives (e.g. plant, wood, wall etc.). The magnetic field 6 can be focused by means of a magnetic lens or other design to produce a kill zone where the target 1 is located. The kill zone shape can be rectangular, conical, hemispherical or any other suitable geometry. Ideally the kill zone will be sharply defined such that any beneficial invertebrate outside the kill zone is not harmed. The target 1 can be any pest, vertebrate or invertebrate. However, the present invention is primarily aimed at invertebrates. Preferably, there will be an immediate killing knockdown of these, but sufficient damage to prevent breeding or feeding or any other operation may be acceptable. There may only be a deterrent effect required, for example to protect a valuable building against termite attack.
[0091] FIG. 5 illustrates application of the MIHPC method of the present invention for agricultural crop use and comprises a tractor or other propulsion device 10 having a boom or similar 12 connected to a high-tension power supply 13, run off a 24 V battery or using the vehicle's power supply, using power cabling 14. The boom or similar 12 is connected to one or more nozzles 15, which generate a magnetic field of 1 MHz-400 MHz frequency, millitesla to tens of millitesla field strength and are shielded against electromagnetic noise. The nozzles 15 produced a high-frequency magnetic field 6 focused on to invertebrate invested crops. The device according to the invention can easily be retrofitted onto existing farm machinery for killing invertebrate pests. This is similar to the FIG. 1 shown in WO8809616A1, except there the inventor used microwaves.
[0092] FIG. 6 illustrates application of the MIHPC method of the present invention for horticultural use. In this embodiment, a boom or other device 12, such as a sprayer is mounted on a movable trolley 20 which may be motorised or not. In this example, the boom or similar 12 is connected to a high tension power supply 23 run off a 24 V battery or mains supply, using power cabling 14. The boom or similar 12 is connected to one or more nozzles 15, 15 which generate a magnetic field of 1 MHz-400 MHz frequency, millitesla to tens of millitesla field strength and are shielded against electromagnetic noise. A high-frequency vertical magnetic field 6, is focused on to invertebrate invested crops. In addition, one or more horizontal nozzles 15 may be provided to generate a high-frequency horizontal magnetic field 6, which is suitable for focusing on invertebrate invested grow bags or pots. The advantage of this embodiment is that it can be used for small plots or polytunnels. Furthermore, this embodiment, can also be used against vertebrates, e.g., killing moles or rats in the ground. This is similar to the FIG. 1 in patent U.S. Pat. No. 2,223,813A, which used an E-field generator as opposed to a B-field generator.
[0093] FIG. 7 illustrates application of the MIHPC method of the present invention to a simple hand-held tin 32 for personal use. Again, the tin 32 is connected to a high tension power supply run off low voltage rechargeable or other battery or power supply connected to a nozzle 15 to generate a magnetic field 6 of 1 MHz-400 MHz frequency, millitesla to tens of millitesla field strength and shielded against electromagnetic noise. This high frequency magnetic field 6 may be aimed at domestic invertebrate pests inside a house, or outside on paths or plants. In this embodiment, the device may be used for domestic pests including flies, ants, caterpillars, etc. in much the same way as a tin of aerosol spray.
[0094] FIG. 8 illustrates application of the MIHPC method of the present invention to food packaging lines comprising a propulsion device such as a conveyor belt 40, which transports a foodstuff in proximity to a gantry 42 containing a power supply and power cabling (not shown) to generate a high-frequency magnetic field 6 of 1 MHz-400 MHz frequency, millitesla to tens of millitesla field strength and shielded against electromagnetic noise. In this embodiment, the magnetic field generator 45 is integrated into the gantry 42. This embodiment of the invention can be used for packaging lines in third-party countries, and the magnetic field generator 45, such as a solenoid or other coil that circumscribes the entire food packaging conveyor belt 40. This is similar to the FIG. 5 in patent U.S. Pat. No. 2,485,660A, which used an E-field generator as opposed to a B-field generator.
[0095] FIG. 9 illustrates application of the MIHPC method of the present invention to grain harvesters, grain silos, grain shipping or other produce flow, where pests (vertebrate or invertebrate) are present. In this embodiment of the invention, a grain handling device comprises a plastic or other non-conducting material grain flow pipe 52, one or more magnetic field generating device 5 to generate a high-frequency magnetic field/s 6 of 1 MHz-400 MHz frequency, millitesla to tens of millitesla field strength and shielded against electromagnetic noise. Another application for this current design in FIG. 9 is for treatment of invertebrate infestations in trees, as per the invention in U.S. Pat. No. 2,223,813A. However, the advantage of the present invention is that a B-field can penetrate deeper into the tree than an E-field, as tree sap (water) is transparent to B-fields and opaque to E-fields. This embodiment of the design can include an annular magnetic field generator 5, such as a solenoid or other coil that circumscribes the entire flow pipe 52.
[0096] Although several embodiments of the present invention have been described above, it will be apparent to those skilled in the art how the MIHPC method of the present invention may be optimised for other uses against various pests.
