Patent Application
20060042155
The invention relates to providing a gaseous product for attracting insects and, in particular, to use of nitrogen dioxide for insect attraction and to enhance the effectiveness of other insect-attracting gases.
Devices for attracting and destroying insects are well known in the art. These prior art devices employ a number of mechanisms and materials to attract insects such as, for example, heat, light, odor emitting substances, pheromones, kairomones, and various chemicals. Researchers in the field of entomology have discovered that biting insects such as midges, biting flies, and mosquitoes are attracted to blood hosts by the odor of kairomones, which are chemicals given off by the blood host and act as attractants to such biting insects. For example, such kairomones include carbon dioxide, exhaled by both avian and mammalian blood host, and octenol, an alcohol that is given off by mammalian blood hosts. It has been shown that mosquitoes and biting flies can detect the odor of carbon dioxide given off by a blood host at a distance of approximately 90 meters [“The Tsetse (Diptera: Glossinidae) Story: Implications for Mosquitoes”, S J Torr, JAMA 10(2):258-265, 1994 (“Studies using electric nets placed at various distances downwind of a host show that a plume of odor from a single ox elicits upwind flight 90 m downwind of the source (Vale 1977 a)”)]. Biting insects locate a blood host by tracking the carbon dioxide plume created by a blood host. It has been discovered that a mixture of carbon dioxide and octenol is especially attractive to insects seeking mammalian blood hosts. Examples of devices employing carbon dioxide and Octenol are, for example, disclosed in U.S. Pat. Nos. 5,205,064 and 6,055,766.
In a preferred embodiment of the method of the present invention, NO2 is used as an attractant enhancer in conjunction with CO2. NO2 may also be used to enhance other attractants, alone or in combination, such as Octenol, thermal or light lures, or any other insect attractant known in the art. There are several preferred embodiments of the apparatus of the present invention. In one embodiment, NO2 is produced by a device that generates the gas through electrical means, such as through an ozone-generator device. The NO2 generator of this embodiment may be employed alone or in combination with a supplemental source of CO2 or other attractant supplied from bottles or generated. In another embodiment, a mix of NO2 and CO2 from bottles, with or without other attractants, is provided for use in a trap designed for use with pressurized gas canisters. In yet another embodiment, an NO2 generator or a small bottle of NO2 is retrofitted to a CO2-generating propane mosquito trap, with or without other attractants.
The present invention demonstrates that the inclusion of very small amounts of NO2, on the order of 200 ppb or less, enhances the effectiveness of CO2 or other attractants as much as ten-fold. One of the primary advantages of this invention is that it permits use of greatly reduced levels of the other attractants, thereby greatly increasing the intervals between necessary replenishment of those attractants in a trap and concomitantly decreasing the costs associated with the purchase and replenishment ofthose attractants. While the preferred embodiment of the present invention employs NO2 as an attractant enhancer, it has also been shown that NO2 alone acts as an attractant for at least some species.
The invention is illustrated, but not limited by, the embodiments shown in the accompanying drawings in which:
Blood seeking insects, particularly mosquitoes, have been shown to have carbon dioxide receptors around the base of their antennae. Normally, about 50 cc/min carbon dioxide, which binds to the insects' receptors, is required to elicit host-seeking behavior in most species of biting flies, midges and mosquitoes. In the present invention, it has been discovered and demonstrated that the attractiveness of carbon dioxide and other insect attractants is greatly enhanced by the addition of nitrogen dioxide (NO2). In the presence of the insect-attracting gaseous product containing NO2 of this invention, much larger collections of insects have been achieved with less carbon dioxide than with carbon dioxide alone. Further, in the present invention it has been discovered and demonstrated that nitrogen dioxide alone has insect-attracting properties, whether generated by a canister, an ozone-generator apparatus, or any other method known in the art.
In the preferred embodiment of the method of the present invention, NO2 is used as an attractant enhancer in conjunction with CO2. While a preferred use of NO2 as an attractant enhancer is in conjunction with CO2, NO2 may also be used to enhance other attractants, alone or in combination, such as Octenol, thermal or light lures, or any other insect attractant known in the art. There are several preferred embodiments of the apparatus of the present invention. In one embodiment, NO2 is produced by a device that generates the gas through electrical means, such as through an ozone-generator device. The NO2 generator of this embodiment may be employed alone or in combination with a supplemental source of CO2 or other attractant supplied from bottles or generated. In another embodiment of the present invention, a mix of NO2 and CO2 from bottles, with or without other attractants, is provided for use in a trap designed for use with pressurized gas canisters. In yet another embodiment of the present invention, an NO2 generator or a small bottle of NO2 is retrofitted to a CO2-generating propane mosquito trap, with or without other attractants.
In one embodiment, the invention can employ any suitable ozone-generating device to produce an insect-attracting gaseous product that includes nitrogen dioxide, such as the device disclosed in co-pending U.S. patent application Ser. No. 10/723,421, filed Nov. 26, 2003, and herein incorporated by reference. An advantage of this embodiment over one requiring a gas or propane canister is that it provides a source of insect-attracting gas containing NO2 that does not require frequent monitoring and/or replacement, as is required for sources of propane, CO2, pheromones, and/or other attractants in a canister. This is particularly useful with respect to nitrogen dioxide, about which there may be environmental and/or safety concerns when provided in a pressurized state. In an alternate embodiment, the ozone-generating device of this embodiment is employed to provide the NO2 in combination with a supplemental source of CO2, which is supplied by any mechanism known in the art, such as by supply from a pressurized canister or by generation from propane.
Ozone generators, whether corona wire or UV, tear apart molecular oxygen and nitrogen from the atmosphere and make a soup of atomic oxygen and nitrogen that are free to combine to form O2, O3, N2, NOx, etc. There are many oxides of nitrogen, but only NO and NO2 are stable in atmosphere. NO is stable for only about 50 minutes, after which it oxidizes into NO2. As atmospheric air flows through the ozone generator, ozone (O3) and other gasses, such as nitrogen dioxide, are therefore continuously produced. The ozone-generating device of this embodiment is typically equipped with a source of activated carbon, such as by either placing the source of activated carbon in the ozone generator device or in fluid communication with the ozone generator so that the ozone produced by the generator is caused to flow through the activated carbon. As the ozone and other gases flow through the activated carbon, the ozone is converted into diatomic oxygen (O2) and carbon dioxide. A gram of activated carbon has hundreds of square meters of surface area. The atomic soup enters the microfissures of the activated carbon and reacts with itself. By passing the atomic soup through activated carbon, some reactions are therefore allowed to proceed to completion because the atomic soup is confined for a time. During this process, O3 becomes O2, or reacts with NO to become NO2, etc. Removing the generated O3 by this method is useful, because it appears to be a repellent. As an added bonus, any hydrocarbons from the atmosphere that happen to be captured by the activated carbon react with the O3 to form CO2 and H2O, improving the overall attractiveness to mosquitoes of the generated gas. For this reason, CO2 production by the ozone-generator device peaks as soon as the ozone generator is turned on and then falls off within 20 or 30 minutes. During the peak CO2 production, hydrocarbon contaminates in the activated carbon are being burned off. When they are gone, the device produces much less CO2. Passing ozone through the activated carbon therefore allows time to for the conversion of O3 into O2, NO2, and CO2. The O2, carbon dioxide, and other gasses, if present, then are caused to pass, such as by a fan, suction pump, by convection or by any other suitable apparatus or means, into any suitable insect attracting and/or destroying trap or apparatus where the insect-attracting gaseous product is employed with any other physical and chemical attractants to attract the insects to an entrapment device.
In FIGS. 1 to 3 there is shown an illustrative ozone generator equipped with an activated carbon source for providing an insect-attracting gaseous product containing NO2 in accordance with this invention for use with an insect entrapment device. The ozone generator can be any suitable device for generating ozone from air, such as for example, UV light generators and corona discharge generators. In a UV light generator, a plasma tube, such as a mercury plasma tube, is used to generate UV light of wavelengths sufficient to dissociate diatomic oxygen in air into atomic oxygen that then combines with other diatomic oxygen in the air being drawn or forced into the generator to form ozone. Such an UV ozone generator is available from Prozone, Inc. of Huntsville, Ala. In a corona discharge ozone generator the ozone is generated by a surface discharge phenomenon between a high-voltage electrode and a low-voltage electrode, which phenomenon is used to ionize air being drawn or forced through the device and between the two electrodes. Such an ozone generator is available from Air-Zone Inc. of Hampton, Va. Among such suitable corona discharge ozone generators available from Air-Zone are their models Air-Zone XT-400 and XT-800. FIGS. 1 to 3 illustrate the invention with a corona discharge ozone generator. Any suitable source of activated carbon, in any suitable shape or form, can be utilized in the process and apparatus of this invention. As an example of suitable activated carbon there may be mentioned an activated carbon mesh pane of the type use as filters, e.g., Honeywell, Inc.'s Activated Carbon Prefilter # 38002.
In FIGS. 1 to 3 there is illustrated an ozone generator 10 modified to produce an output of an insect-attracting gaseous product according to the present invention. The ozone generator 10 comprises a housing 12 of any suitable shape, the shape being shown as rectangular in FIGS. 1 to 3. The housing 12 comprises four joined side panels 14. The housing 12 is provided with leg supports 16, preferably at or near the four corners of the housing, to provide a space for a flow of air, indicated by arrows A, to be drawn or forced into and through the housing. The housing 12 generally has an open-grated bottom panel or panel with vents 18 to permit flow of the air into the generator housing. The top of the housing 12 is provided with a cover panel 20 which has a vent or discharge element 22 projecting generally perpendicularly from the cover panel for providing means to discharge the gaseous products of the generator, as indicated by arrows B. The vent element is preferably a tapered conduit.
In the embodiment illustrated, the generator 10 is provided with an electrical lead 24 and plug 26 for connecting the device to a suitable outlet of an electrical power source (not shown). The device could, however, be powered by a battery unit as the electrical power source. An off/on switch 28 is provided on the housing 10 for activating or deactivating the electrical power source. The generator unit 10 can also be provided with plug receptacle 29 for providing electrical power for a purpose to be explained later. Electrical leads 30 and 32 are provided for connecting the electrical power to a transformer 34 in the housing 10. Transformer 34 outputs suitable voltage/current via electrical leads 36, 38, 40 and 42 to electrodes 44 and 46 located in the lower portion of the housing proximate the open-grated bottom panel 18. Each electrode comprises two metal screen grids 48 and 50, separated by a ceramic core 52 held together by an insulating cap 54. In housing 10, between the electrodes 44 and 46 and the vent 22, there is located an activated carbon element 54, such as a Honeywell, Inc. Activated Carbon Prefilter # 38002, positioned so that air or oxygen that has been subjected to corona discharge from the electrodes 44 and 46 has to pass through the activated carbon element to reach the vent. A support element 56 attached to cover 20 supports a fan 58 located in the entrance 57 of vent 22. Fan 58 is electrically connected to the power source by electrical leads 60 and 62 and operates to draw air A into housing 10 through open grated bottom panel 18 and force gaseous products B out vent 22. If desired, the generator 10 may be provided with a remote control and means activated by the remote control for operating the unit, such as for example, to turn the unit off or on.
When electrical power is provided to the generator unit 10 and the unit is turned on via switch 28, fan 56 draws air A into the unit where the air passes through the corona discharge provided by electrode elements 44 and 46 and ozone and other gasses, such nitrogen dioxide, is produced. The ozone and other gasses are then forced by fan 56 to be drawn into contact with the activated carbon 54 where ozone is reacted with other molecules to form nitrogen dioxide, carbon dioxide, and diatomic oxygen. The activated carbon serves to remove the ozone from the system. The nitrogen dioxide, carbon dioxide, diatomic oxygen, and any other gasses are then forced by the fan 56 to exit the housing 10 through vent 22, thereby providing an insect-attracting gaseous product containing nitrogen dioxide.
In
It will be appreciated that, although the invention has been illustrated in
It has been found that the ozone-generator device of this embodiment performs best when the humidity is not unusually high. Humidity appears to inhibit the process employed by the device because it appears to coat the activated carbon, thereby stopping the reaction. As a result, more O3, less NO2, and almost no CO2 are produced. A heater or dryer to drive water from the activated carbon and keep the reaction going is therefore recommended for operation in humid conditions. Silica gel may also be used to absorb humidity from the air entering the device.
The present invention demonstrates that a gaseous mixture of carbon dioxide with nitrogen dioxide acts as an improved attractant compared to carbon dioxide alone. It has been demonstrated in tests that insect attractiveness can be increased 10-fold or more over carbon dioxide alone when the insect-attracting gaseous mixture containing nitrogen dioxide produced by an activated carbon modified ozone generator is employed as the attractant.
For example, three mosquito traps were tested in field trials lasting nine days in October 2002. The test protocol was a 3 by 3 Latin Square in which three commercially available Dragonfly traps manufactured by BioSensory, Inc of Willimantic, Conn. were baited with different attractants. Trap Number 1 was baited with octenol and a pulsed discharge of 250 ml/min CO2 from a canister, producing CO2 concentrations of approximately 7000 parts per million at the discharge point. Trap Number 2 was baited with octenol alone. Trap Number 3, referred to as the “Transmogrifier”, was baited with octenol and a preferred embodiment of the insect-attracting gaseous product of this invention in a continuous discharge, the insect-attracting gaseous product of these tests initially containing a CO2—NOx mixture having CO2 concentrations of approximately 750 parts per million at the discharge point, with the CO2 concentration of the mixture falling to levels that were indistinguishable from ambient levels within one hour while the NO2 concentration remained steady. Three test locations were established at mosquito-infested areas near Tweed Airport in East Haven Conn. Each trap was tested at each location overnight. Every day mosquito collections in each trap were removed, identified by species, counted and recorded. Traps were then rotated to the next test location and the test was repeated that night. In order to test each trap at each location, one complete rotation of the protocol required three nights. The test protocol was repeated three times over nine consecutive nights. Data from this field trial appears in Table 1.
Although Trap Number 3 was found to be generating only one-tenth the amount of CO2 compared to the emissions of Trap Number 1, and these amounts dropped to levels that were indistinguishable from ambient levels within one hour, its collections were equal to 44.8% of the collections of Trap Number 1 and were drawn from a larger number of mosquito species. Compared to Trap Number 2, which had no CO2 emissions, Trap Number 3 collections were 420% larger and were drawn from twice as many mosquito species.
In another example, in a September 2003 field trial, two mosquito traps were tested in field trials lasting five days. In this trial, two commercially available Dragonfly traps manufactured by BioSensory, Inc were baited with different attractants. A first trap was baited with a pulsed discharge of 180 ml/min CO2 from a canister, Octenol released at approximately 3.5 mg/hour, and heat from a thermal lure. A second trap, the same “2002 Transmogrifier” used in the October 2002 field trial, was baited with Octenol and an ozone-generator-produced insect-attracting gaseous mixture containing NO2 in a continuous discharge, the gaseous mixture initially containing a CO2—NO2 mixture, with the CO2 concentration of the mixture falling to levels that were indistinguishable from ambient levels within one hour. Two test locations were established at Thill Street, West Haven, Conn. Each trap was tested at each location overnight. Every day mosquito collections in each trap were removed, identified by species, counted and recorded. Traps were then rotated to the other test location and the test was repeated that night. The test protocol was repeated over five consecutive nights. The results of this field trial are shown graphically in
In
The emissions from the “2002 Transmogrifier” trap used in the October 2002 (“Trap Number 3”) and September 2003 field trials were measured in the laboratory in May 2003. Gas concentrations were assayed with a Thermo Environmental Instruments (TEI) 42C—NO—NO2—Nox Analyzer. Results to the nearest 0.1 ppb were displayed digitally and recorded. Gas emanating from the “Transmogrifier” was sampled through one end of a flexible plastic tube affixed just inside the 4-inch diameter exhaust port (and in a quadrant with obvious outward flow), and the gas sample was drawn continuously into the TEI NOx Analyzer. The goal was to measure the output of NO and NO2 from the functioning “Transmogrifier” versus background levels. Sufficient time (3-10+ minutes) was allowed for the readings to stabilize before measurement. Table 2 summarizes the measurements recorded. As can be seen, when the “2002 Transmogrifier” was running with all three plates in place, the concentration of NO corresponded to background, but that of NO2 was significantly greater than background.
After the September 2003 field trial, in November 2003, laboratory tests were again performed on the 2002 Transmogrifier device. These tests also used the TEI analyzer, and also used a Vaisala handheld CO2 meter. The analyzer wand was positioned at the exhaust port of the Transmogrifier, and the digital output was recorded at one-minute intervals. Measurements were taken and recorded during intervals when the Transmogrifier device was configured as follows (in order): Electrical Plug Out/Switch Off, Electrical Plug In/Switch Off; Electrical Plug In/Switch On, and Electrical Plug In/Switch Off.
A plot of the tabulated data from this test is shown in
In another embodiment of the present invention, a mix of CO2 and NO2 from bottles is provided for use in a trap designed for use with pressurized gas canisters.
During trap operation, CO2 is discharged into the trap at CO2 discharge 790 from canister 735 and the NO2/air mixture is discharged into the trap at NO2/air discharge 785 from secondary canister 745. Insects are attracted to the trap by the combined gas lures and/or the combination of the Octenol 730 and/or light lure 795 with the NO2/gas mixture. Battery 715 powers motor 775 via power leads 720 to run fan 780. The movement of fan 780 causes air to flow into 760 the trap at the top, through 798 the fan area, and out 765 at a screened area at the bottom of the collection bag. Insects attracted to the trap by the lures are thereby pulled into the trap and down into collection bag 710. While the embodiment depicted shows a particular trap configuration, it should be clear to one of ordinary skill in the art that any subset or combination of the elements shown, any other elements known in the art for use in insect traps, or any other suitable insect trap or killing device known in the art and adapted or adaptable for use with pressurized gas canisters may be used in the present invention. In particular, the present invention may employ other types of power sources, such as a rectified or AC power source, and may also advantageously employ photocells or timers in order to control the times of release of the NO2 and other gasses, thereby conserving them by limiting gas release to those times of day when mosquitoes are particularly problematic.
This embodiment of the invention was demonstrated in, for example, a field trial performed in March of 2004. In this trial, two mosquito traps were tested over three days. The test protocol was a 4 by 4 Latin Square with two replicates in which two CDC traps were baited with different attractants. The CDC traps utilized for this trial were standard battery-powered fan traps that emit gas from pressurized canisters. The trap baited with NO2 was constructed in accordance with the embodiment of
The results of this field trial are summarized in Table 3 and depicted graphically in
The present invention demonstrates, therefore, that the inclusion of very small amounts of NO2, at a discharge rate on the order of 0.2 cc/min or less, enhances the effectiveness of CO2 or other attractants as much as ten-fold. One of the primary advantages of this invention is that it permits use of greatly reduced levels of the other attractants, thereby greatly increasing the intervals between necessary replenishment of those attractants in a trap and concomitantly decreasing the costs associated with the purchase and replenishment of those attractants. It should be noted that care should be taken to ensure that the NO2 levels supplied are not overly large, as data suggests that very high levels may repel, rather than attract, mosquitoes. Note that the NIOSH (National Institute for Occupational Safety and Health) IDLH (Immediately Dangerous to Life or Health) concentration for NO2 is 20 ppm (20,000 ppb). As a practical limit, OSHA currently specifies a Permissible Exposure Limit (PEL) for NO2 of 5 ppm (5000 ppb), which level has been shown by these tests to be very attractive to mosquitoes.
In yet another embodiment of the present invention, an NO2 generator or a small bottle of NO2 is retrofitted to a CO2-generating propane mosquito trap. In this embodiment, the ozone-generator device described in conjunction with
While the preferred embodiment of the present invention employs NO2 as an attractant enhancer, it has also been shown that NO2 alone acts as an attractant for at least some species. In particular, it appears that more primitive species found around fresh-water lakes, such as Mansonia dyari and Coquillettidia perturbans, are attracted equally to NO2 and CO2. It is speculated that perhaps these more primitive mosquito species have more generalized receptors that cannot differentiate NO2 from CO2.
This embodiment of the invention was demonstrated in, for example, a Mesozoic Landscape trial performed in December 2003 in Lantana, Fla. In this trial, four mosquito traps were tested over 5 days. The test protocol was a 4 by 4 Latin Square with two replicates in which two standard CDC traps were baited with CO2 and an Octenol lure. The CDC traps utilized for this trial were standard battery-powered fan traps that emit gas from pressurized canisters. The other two traps were the 2002 Transmogrifier shown in
The results of this field trial are summarized in Table 4. In Table 4, it can be seen that, while all the traps tested captured mosquitoes, Mansonia dyari represented a much higher percentage of the collections of the two Transmogrifier traps baited with NO2 than of the collections of the two CO2-baited CDC traps.
The present invention therefore provides methods and apparatus for insect attraction through the use of nitrogen dioxide. Nitrogen dioxide is used both for insect attraction and to enhance the effectiveness of other insect-attracting gasses. While the invention has been described herein with reference to the specific embodiments thereof, it will be appreciated that changes, modification and variations can be made without departing from the spirit and scope of the inventive concept disclosed herein. Accordingly, it is intended to embrace all such changes, modification and variations that fall with the spirit and scope of the appended claims.
This application is a continuation-in-part of U.S. patent application Ser. No. 10/723,421, filed Nov. 26, 2003, which claims the benefit of U.S. Provisional Patent Application No. 60/430,323, filed Dec. 2, 2002, both of which are herein incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60430323 | Dec 2002 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10723421 | Nov 2003 | US |
| Child | 11185586 | Jul 2005 | US |
