WO2010148473A1

WO2010148473A1 - Method for insect control

Info

Publication number: WO2010148473A1
Application number: PCT/CA2009/000888
Authority: WO
Inventors: Norma O'hara
Original assignee: Terrghia Incorporated
Priority date: 2009-06-25
Filing date: 2009-06-25
Publication date: 2010-12-29

Abstract

A method is described for emitting an insect control signal to create a protected zone, into which insect entry is minimized. The use of complex waveforms is described. First and second acoustic signals are emitted, each at a frequency of 30 - 300 Hz. The precision, frequencies, and waveforms of the signals are described, specifically with respect to mosquito control. The signals are believed to impair the ability of the insect to navigate a flight path into the protected zone.

Description

Method for Insect Control

FIELD OF THE INVENTION

The present invention relates generally to methods for insect control. More particularly, the present invention relates to a device for emitting an insect control signal to generate a protected zone; and to a method for controlling insects, for example by interrupting insect flight navigation within the protected zone.

BACKGROUND OF THE INVENTION

Insects such as mosquitoes, sand flies, black flies, gnats, moths, and migies are typically viewed as bothersome pests in first world countries. However, in many developing countries, insects are also responsible for transmission of diseases, having dire consequences on the human population in those areas.

Mosquitoes currently cause over four million human deaths per year due to their propagation of deadly diseases including malaria and West Nile virus. Black flies transmit tularemia and onchocerciasis. Leishmaniasis, a disfiguring and often fatal parasitic disease, is spread by the bite of infected sand flies and currently affects approximately 12 million people worldwide. Although many initiatives are underway to control these diseases and prevent their spread in developing countries, there is currently no practical, effective way to avoid exposure to the insects carrying these diseases.

Current insect avoidance technologies include simple physical barriers such as nets for placement over beds and cribs, repellent sprays and cartridges, and high frequency emitting devices that are intended to simulate the signals emitted by insect predators. With respect to mosquito avoidance, N,N-diethyl-m-toluamide (DEET) remains the gold standard for human personal repellents and is also effective against biting flies, chiggers, fleas, and ticks. Malathion is an insecticide commonly used for fogging to control mosquito populations. Permethrin is a broad-spectrum toxin used for killing insects and mites. Permethrin may be applied directly to clothing to kill insects upon contact, however, caution should be exercised in using permethrin in combination with DEET repellents as severe cellular damage may result. It has been reported that thousands of Canadians suffer acute poisoning from insect spray/pesticides every year. In addition, many of these chemicals are suspected to increase the risk of cancer, neurological diseases, and organ damage in heavily exposed individuals. Moreover, as these control methods are weather- dependent, insect populations may be difficult to control if weather conditions are unfavourable.

Insect traps and electrocution devices have been developed to control insect populations within a specific zone, for example, a residential yard. In a typical system, an attractant such as ultraviolet light attracts insects towards an electrically charged grid. These devices are non-specific in that harmless non-target insects are destroyed along with mosquitoes. Further, most of these devices do not mimic human attractants such as moisture and carbon dioxide, and are therefore only mildly effective against mosquitoes and completely ineffective against biting flies. In addition, the by-products of insect electrocution include moth wing scale fragments and metal particles, which may result in serious allergic reactions or other health issues. Moreover, these systems are not portable, and therefore are not suitable for providing protection to a participant in outdoor recreation activities, such as hiking, camping, boating, fishing, etc.

High frequency signals have been the subject of recent technologies, attempting to mimic the frequency of male mosquitoes (which are supposedly avoided by biting pregnant female mosquitoes) or other insect predators such as the dragonfly. These devices typically produce an audible whining sound and thus have proven annoying as well as ineffective.

Eradication of insect species is not feasible or desirable, as insects are a critical part of the food chain in most environments. There must therefore be a balance between protection of human interests and maintenance of the environment and natural food chain.

It is known that many creatures, including migratory birds and turtles, use magnetic fields to orient themselves and navigate within their environment. Similarly, it is suspected that an insect's ability to navigate towards a source of food requires sensing of electromagnetic pathways within the environment. Recent evidence suggests that insects, birds, and potentially some animal species are able to sense the earth's magnetic lines, and may even perceive these pathways as patterns of color or light intensity superimposed on their natural surroundings. The prior art includes widely varying examples of methods to control insect activity through emission of signals. For example, US 5,528,049 describes the emission of radiation frequencies and photonic waves to emulate natural insect attractant or repellent signals. US 7,109,849 describes a device for emitting a mosquito dispersing pitch pattern, having a frequency in the range between the wing beat frequency of a dragonfly and the wing beat frequency of a damselfly (20 to 40 Hz). US 4,284,845 and US 6,568,123 also describe devices for emitting attractant or repellent signals.

There is no clear direction in the prior art as to which types of signals and which frequencies are effective in attracting or repelling insects. Specifically, low frequencies in the prior art are taught to both attract mosquitoes towards a trap, and to repel mosquitoes.

To the Applicant's knowledge, none of the prior art signal devices have met with commercial success, and the teachings of the prior art have not been commercially useful.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention, there is provided a method for disrupting insect activity within a zone, the method comprising the step of emitting a complex acoustic signal at a frequency between 30 Hz and 300 Hz to establish a zone of protection within which insect activity is disrupted.

In an embodiment, the method comprises a further step of emitting a second complex acoustic signal within the zone of protection, the second signal emitted at a frequency between 30 Hz and 300 Hz.

In a particular embodiment, each complex acoustic signal comprises a series of irregular wave segments.

In various embodiments, the complex acoustic signal(s) each comprise a series of wave segments, wherein at least one of the wave segments is distinct from surrounding wave segments so as to create at least one irregularity in the complex acoustic wave. For example, the distinct wave segment may be distinct from the surrounding waves in form, amplitude, or duration. In further embodiments, each wave segment may be one of: a sine wave segment, cosine wave segment, triangle wave segment, square wave segment, or sawtooth wave segment.

In an embodiment, the first signal is emitted at a frequency between 180Hz and 190 Hz.

In an embodiment, the second signal is emitted at a frequency between 150 Hz and 160 Hz.

In suitable embodiments, the signal frequency may be precise up to three decimal places. In accordance with a second aspect of the invention, there is provided a method for disrupting insect activity within a zone, the method comprising the steps of: emitting a first insect control signal within a zone at a frequency between 30 Hz and 300 Hz; and emitting a second insect control signal within the zone, the second signal having a frequency between 30 Hz and 300 Hz.

The first and/or second signal may be a complex acoustic wave, each comprised of a series of irregular wave segments.

In an embodiment, the complex acoustic wave comprises a series of wave segments, wherein at least one of the wave segments is distinct from surrounding wave segments so as to create at least one irregularity in the complex acoustic wave. The distinct wave segment may be distinct from surrounding wave segments in form, amplitude, or duration.

In a further embodiment, each wave segment is one of: a sine wave segment, cosine wave segment, triangle wave segment, square wave segment, or sawtooth wave segment.

In an embodiment, the first signal is emitted at a frequency between 180 Hz and 190 Hz.

In a further embodiment, the second signal is emitted at a frequency between 150 Hz and 160 Hz. In certain embodiments, each signal frequency is precise to three or more decimal places.

In an embodiment, the first and second signals are emitted in alternation. In an embodiment, signal emission disrupts insect flight. In certain embodiments, the signal is carried over an AM or FM band. Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein: Fig. 1 a-d are graphs of regular wave forms; and

Fig. 2a-j are graphs of sample complex waveforms.

DETAILED DESCRIPTION

Generally, the present invention provides a method for controlling insects, for example in preventing insect entry into a protected zone. The protected zone is created by emission of one or more acoustic signals within the zone.

While not bound to any particular theory, it is believed that the ability of insects to navigate within their environment requires sensing of electromagnetic impulses and/or other signals naturally present in the environment. For example, a mosquito may navigate towards a blood source by sensing carbon dioxide in the environment and travelling along electromagnetic waves naturally present within the environment towards the carbon dioxide (and blood) source. Thus, the electromagnetic field present in the natural environment may provide pathways for use in navigation by an insect.

Protected Zone

Application of an appropriate additional insect control signal within the environment distorts, cancels, or otherwise disrupts the naturally present electromagnetic fields (or signals) used by the insect for navigation. As a result, the insect becomes unable to function within a certain radius of such insect control signal. When nearing this radius, therefore, the insect becomes disoriented and therefore must avoid the protected zone. It is believed that application of the insect control signal may cause destructive interference with the natural electromagnetic field, disturbing the natural pathways involved with insect navigation.

The protected zone formed by application of the insect control signal is independent of the number of insects outside the radius of the protective signal and, in certain embodiments, is generally independent of weather conditions (although high humidity, winds, or pollution may minimally reduce the radius of protection). Notably, the signal does not directly harm the insects, leaving this level of the food chain intact.

Signal Characteristics

The protected zone is created by the emission of one or more signals to form a protected zone about the emission source. As many fields and frequencies are naturally present within the environment, with various insects using different frequencies for specific purposes, the method may be directed very precisely to one particular insect or effect. For example, interruption of mosquito flight navigation may still permit dragonflies to enter the protected zone. It is expected that there may be some response overlap between species that are closely related or are similar in size. The frequency, acoustic wave shape, and number of signals emitted within the protected zone may all be varied to achieve an insect control signal that is suitable for use with a particular insect and behaviour. Signals tested to date that have been deemed effective in controlling various insects fall within the frequency range of 30 to 300 Hz.

Generally, testing to date has shown that three factors may be manipulated to achieve an appropriate insect control signal - namely, the wave shape of the signal, the frequency at which the signal is emitted, and the number of effective signals applied within the zone.

Wave shape

The shape of the waveform is of importance in generating an appropriate insect control signal. That is, the signal is more effective in creating and maintaining a protected zone if the emitted waveform has certain characteristics.

By increasing the irregularity, or erratic nature of the wave shape, it appears that insect adaptation to the signal can be minimized. For example, a sine wave is smooth and regular in its shape and effect on the surroundings. Application of a sine wave signal therefore provides minimal disruption to the insect, and the insect is able to adapt and re-enter the protected zone after only a short period of flight disruption. Similarly, the typical sawtooth, square wave, triangular wave, etc. are also of limited use in the present application (although these do provide greater effect than the sine wave shape). Such regular wave shapes are shown in Figure 1 a-d, and these wave shapes have been only minimally effective in generating a zone of mosquito avoidance in testing to date. By contrast, highly complex waves, for example of the type shown in Figure 2 a-j, have been more effective in preventing mosquito adaptation and entry into the protected zone.

Second, the harmonics of the wave shape appear to improve the strength or increase the radius of the protected zone. That is, a combination of many even and odd harmonics in the construction of the wave shape is beneficial, creating a more robust protected zone. The complex wave shapes shown in Figure 2a-j may be generally described as being composed from a number of wave segments. For example, with reference to any one of the waves shown, segmenting the wave into sections (i.e. from one rise to the next) results in as many as one hundred wave segments or more. In viewing the wave segments, it is noted that most are generally similar to adjacent or nearby wave segments, providing gradual fluctuations in the overall waveform, with some notable segment exceptions. These exceptions - for example a wave segment with a significant plateau after a rise or fall, or a segment with a greatly exaggerated peak or trough compared to surrounding segments - provide noticeable irregularities in the overall shape of the complex wave. Similarly, these irregularities in the emitted signal are noted by the insect as a disturbance in the environment, perhaps as turbulence in the air. In any event, such complex signals appear to increase zone avoidance and prevent adaptation by the insect to the signal. As such, a great degree of complexity and irregularity in the emitted wave shape increases the protection afforded within the zone. Complex waves may be used at varying frequencies to control activity of various insects. The complex waveforms may be created by additive synthesis. To date, tested waveforms have been created using a Tektronix™ waveform generator, which allows the user to control the complexity and design of the waveform. The resulting signals may be emitted at any suitable frequency.

Frequency The desired complex wave shape is emitted (with or without an accompanying audible sound) constantly at a specific frequency, or oscillating across a range of frequencies.

Frequencies between 30 Hz and 300 Hz have been effective in establishing a protected zone, depending on the insect in question. It appears that certain specific frequencies are effective in controlling specific species of insects. For example, signals emitted at a frequency between 180 - 190 Hz are generally effective in preventing mosquito entry into the protected zone, as are signals emitted within a range of 150 - 160 Hz. However, these ranges are not necessarily effective in preventing dragonfly entry into the protected zone. It is believed that insect receptors are highly sensitive, and respond more effectively to very precise signals. Specifically, testing to date in mosquito protection has shown that when the signal is accurate to three decimal places of precision, a more effective mosquito-free zone may be generated by application of a suitable insect control signal. It is expected that a more precise signal may produce similar or possibly more effective results, while a precision of only two decimal places has been less effective. Dual Signal

It has been found during testing that the protected zone is enhanced when two signals are emitted to establish the protected zone. The second signal may be a harmonic or subharmonic frequency of the first signal frequency, or a near- harmonic or near-subharmonic frequency of the first signal. The two signals may be additive in some wave segments and may cause destructive interference in other wave segments. The signals may be different or identical in waveform. This dual signal has been shown during testing to enhance insect avoidance effect by more effectively preventing entry of the specific insect into the protected zone. When only one frequency is used, insects may enter a few inches into the protected zone but then become disoriented and exit the protected zone. When the dual signal system is used, protection within the zone is more complete (ie. further limiting mosquito entry), apparently strengthening the destructive interference of the natural flight pathways used for mosquito flight or otherwise creating a notable disturbance in the natural environment sensed by the mosquito.

Typically, application of a first signal (of complex wave shape) in the range of 180.000 to 189.999 Hz, along with a second SLF signal (also of complex wave shape) in the range of 150.000 to 159.999 Hz, has been found to eliminate the presence of mosquitoes within a zone having a radius of up to six feet. In preliminary testing, it has been determined that as the signal is adjusted to depart from a maximally effective signal (for example a signal frequency that results in a protected zone of six foot radius), a gradual reduction in the radius of the protected zone results. While a minimal radius may provide suitable protection to a user from mosquito bites, the user may wish to maximally extend the zone of protection, for example to avoid closely buzzing insects. Accordingly, the signal may be adjusted as desired. Similarly, departure from a highly complex and erratic wave shape to a more regular wave shape is expected to reduce the protective effect, even when emitted at an otherwise suitable frequency. Addition of a third signal may enhance effect, while emitting only one wave shape at a suitable frequency would reduce the protective effect. Thus, the factors of wave shape, frequency, and signal harmonics (ie. harmonics within one wave shape, and harmonics provided by the interaction of dual signals) all contribute to the degree of protection afforded.

Examples:

Specific frequencies found to be suitable with respect to mosquito control to date fall within the above-noted ranges (ie. 150.000 Hz - 159.999 Hz; 180.000 Hz - 189.999 Hz).

Example settings for use with mosquitoes:

For example, the following signal pair has been found to be successful in effecting protection against mosquitoes using the above settings: Signal 1 : complex wave shape shown in Figure 2e, emitted at 186.428 Signal 2: complex wave shape shown in Figure 2e, emitted at 157.537

In addition, variations in environmental conditions may affect the signal in some embodiments. For example, if the waveform does not have sufficient irregularity and provides only a minimal radius of protection, the environmental conditions may result in further minimization of the radius of protection. For example, surrounding minerals, atmospheric pressure, etc. may affect the signal or the insects to some degree. It is expected that an insect may be able to operate within several closely related frequency ranges to accommodate changes in the natural environment. Accordingly, it is conceivable that the protected zone may benefit from refinement of the signal from one environment to another, however testing to date indicates that such refinement is not necessary, as the environment has had negligible impact on the protected zone established during testing.

Of further note is the observation that the inherent conductivity of the human body seems to extend the effective radius of protection. For example, when the protected radius from the emitter is three feet, one would expect that placement at the waist of a user could result in the user's head and feet being unprotected. However, in testing, it appears that the radius instead extends approximately two feet from the user at any location on the user's body.

Device

A signal generator for emission of low frequency acoustic signals of adjustable waveform was procured and used for testing purposes. Such devices are generally available. The device tested was adjustable between 0.000 Hz and 25MHz, and signals were emitted through a 10 inch speaker. For dual signal testing, two or more signals were selected and a combiner was utilized to combine both sound waves and emit them together through the single speaker. The signals may be oscillated or pulsed to conserve power, potentially allowing the device to be powered by solar cells. Pulsing of the signal may also further limit insect adaptation to the signal.

The above-described embodiments of the present invention are intended to be examples only. Alterations, modifications and variations may be effected to the particular embodiments by those of skill in the art without departing from the scope of the invention, which is defined solely by the claims appended hereto.

Claims

What is claimed is:

1. A method for disrupting insect activity within a zone, the method comprising the step of:

- emitting a complex acoustic signal at a frequency between 30 Hz and 300

Hz to establish a zone of protection, within which insect activity is disrupted.

2. The method as in claim 1 , further comprising the step of emitting a second complex acoustic signal within the zone of protection, the second signal emitted at a frequency between 30 Hz and 300 Hz.

3. The method as in claim 1 or 2, wherein each complex acoustic signal comprises a series of irregular wave segments.

4. The method as in claim 1 or 2, wherein each complex acoustic signal comprises a series of wave segments, wherein at least one of the wave segments is distinct from surrounding wave segments so as to create at least one irregularity in the complex acoustic wave.

5. The method as in claim 4, wherein each wave segment is one of: a sine wave segment, cosine wave segment, triangle wave segment, square wave segment, or sawtooth wave segment.

6. The method as in claim 4, wherein the distinct wave segment is distinct from surrounding wave segments in form, amplitude, or duration.

7. The method as in any of claims 1 through 6, wherein the first signal is emitted at a frequency between 180 Hz - 190 Hz.

8. The method as in any of claims 2 through 7, wherein the first or second signal is emitted at a frequency between 150 Hz - 160 Hz.

9. The method as in any of claims 1 through 8 wherein the signal frequency is precise to three decimal places.

10. The method as in any of claims 1 through 9, wherein the insect is a mosquito, and wherein the insect activity is flight.

11. A method for disrupting insect activity within a zone, the method comprising the steps of:

- emitting a first insect control signal within a zone at a frequency between 30 Hz and 300 Hz; and - emitting a second insect control signal within the zone, the second signal having a frequency between 30 Hz and 300 Hz.

12. The method as in claim 11 wherein the first signal is a complex acoustic wave.

13. The method as in claim 11 wherein the second signal is a complex acoustic wave.

14. The method as in claim 11, wherein the first and second signals are both complex acoustic waves.

15. The method as in any of claims 11 through 14, wherein the complex wave shape comprises a series of irregular wave segments.

16. The method as in any of claims 11 through 14, wherein the complex acoustic wave comprises a series of wave segments, wherein at least one of the wave segments is distinct from surrounding wave segments so as to create at least one irregularity in the complex acoustic wave.

17. The method as in claim 16, wherein each wave segment is one of: a sine wave segment, cosine wave segment, triangle wave segment, square wave segment, or sawtooth wave segment.

18. The method as in claim 16, wherein the distinct wave segment is distinct from surrounding wave segments in form, amplitude, or duration.

19. The method as in any of claims 11 through 18, wherein the signal is emitted at a frequency between 180 Hz - 190 Hz.

20. The method as in any of claims 11 through 19, wherein the first or second signal is emitted at a frequency between 150 Hz - 160 Hz.

21. The method as in any of claims 11 through 20, wherein the signal frequency is precise to three decimal places.

22. The method as in any of claims 11 through 21, wherein the signal is an insect flight disruption signal.

23. The method as in any of claims 11 through 22, wherein the first and second signals are emitted in alternation.

24. The method as in any of claims 11 through 23, wherein the insect is a mosquito, and wherein the signal prevents insect entry into the protected zone.

25. The method as in any of claims 1 through 25, wherein the signal is carried over an AM or FM band.