PEST CONTROL DEVICE COMPRISING A DEGRADABLE MATERIAL INCORPORATING A PEST
CONTROL MATERIAL
Description
5 This invention relates to pest control and is especially, but not exclusively, related to the control of insects and other arthropod pests, such as ticks and mites, as well as rodent pests.
10 The widespread use of chemical and biological pest control materials, such as pesticides, in agricultural, horticultural, forestry and public health protection, has led to the development of resistance in pests to a wide range of these
15 materials.
Over use of such pest control materials has caused both widespread pollution and the mortality of many beneficial insects and animals, resulting in 20 bans on their use in many countries.
The above factors have made it desirable to develop new pest control measures which present fewer hazards to farmers, consumers and the environment,
25 which target pest species effectively and which also minimise the amounts of pest control materials used.
Many different types of pest control device and techniques have been developed, one such technique
30 being known as mating disruption which uses pheromone dispensers placed in an environment, such as a crop environment, to be protected. For a review of the
current technology, see Howse, Stevens & Jones: Insect pheromones and their role in pest management, Chapman & Hall 1998. In this technique, a dispensing device contains a charge of the sexual attractant pheromone of the species to be controlled. The device regulates release of the pheromone, such that it is maintained in the air around an environment to be protected, for example, a crop environment, for periods of weeks or months.
Normally, a male will follow the windborne scent to its source in order to find a female with which it then mates .
Mating disruption is believed to act through two main mechanisms, namely, diversion to individual dispensing devices, sometimes known as false trail- following, and habituation in which loss of sensitivity of the male to pheromone as a result of prolonged exposure thereto, occurs.
There are, however, disadvantages associated with this type of dispensing device. For example, numerous devices are needed to maintain a concentration of pheromone high enough within the crop to interfere with the ability of male insects, for example, a moth to pick up windborne plumes of pheromone emitted by females of the same species .
The dispensing device mentioned above can be manufactured in several different forms, including hollow fibres, plastic flakes, twist-tie wax ropes
and slow-release capsules. All these forms must be designed to hold and liberate relatively large amounts of pheromone continuously to keep the concentrations of pheromone around the crop high. Because pheromones in general are expensive to synthesise, due to their high purity requirements, these pest control devices are relatively expensive and commonly have to be distributed at around 400- 1000 per hectare. These requirements for the devices to be sufficiently effective are, therefore, costly and time consuming.
Published International Patent Application, No. WO 94/00980 (Howse) discloses the use of electrostatically-charged particles as a means of contaminating insects with synthetic or biological insecticides, or with other biologically active materials, such as semiochemicals, for example pheromones and other attractants. Published International Patent Application No. WO 00/01236 discloses the use of magnetic particles for similar purposes. Published International Patent Application No. WO 01/28322 discloses a means of distributing electrostatically-chargeable or magnetic powders in a dispenser. The dispenser has biodegradable entry ports which open when the dispenser is placed in the desired environment. This type of dispenser is particularly suitable for distribution from aircraft over forests or extensive agro-ecosystems.
A disadvantage of these currently developed dispensers which utilize electrostatically-charged or
magnetic particles, is that the powder may be blown from the dispenser by high winds or washed out by rainwater, thus reducing the efficacy of the dispensers. A further disadvantage is that volatile materials formulated in the powder may be lost too quickly into the atmosphere, so that the dispensers cease to be efficacious before pest control has been achieved.
A further disadvantage is that the dispenser' s container for the powder must be fabricated separately and requires special adaptations of aircraft to allow efficient dispersal when aerial application is desirable in order to cover large areas effectively.
Accordingly an object of the present invention is to provide a pest control device and associated method which eliminate, or at least substantially reduce, the disadvantages associated with the known types of pest control device and method currently in common use and discussed above.
Accordingly, a first aspect of the invention provides a device for controlling pests, comprising a degradable material incorporating a pest control material .
The degradable material is preferably in the form of a matrix which is most preferably solid.
This arrangement is most advantageous because the pest control material is held in the degradable material for subsequent release therefrom, with, any volatile active ingredient being retained therein.
Degradation of the degradable material results in release of the pest control material from an outer surface thereof. This is advantageous because the pest control material is lost at only the surface of the degradable material, as it becomes freed therefrom, for example, from the matrix thereof. In this way, any pest control material, such as, at the outer surface of the degradable material matrix removed by, say, wind and rain, can be replaced continuously.
The degradable material may comprise any suitable material but preferably comprises a photodegradable polymer, biodegradable polymer, starch-based polymer, hydrolysable polymer, silicon- based polymer or a micro-porous material, for example, an aerogel or any combination thereof.
The degradable material may also comprise an lipophilic material, an oil or any other lightly adhesive material. These substances coat the pest control material which is released at the surface of, say, a matrix, to form particles which may adhere to the cuticle of a pest. Any such particles are preferably of a size less than 50 microns.
The pest control material incorporated with the degradable material preferably comprises a powder which may be an electrostatically-chargeable powder, for example, a wax, such as a natural wax, or a plastics polymer, or metallic particles, such as a magnetic powder.
The pest control material most preferably further comprises a pesticide, insecticide, rodenticide, pathogenic fungal spore, entomopathogenic bacilli, semiochemical, natural product chemical or behaviour modifying chemical or any combination thereof. Any behaviour modifying chemical present in the pest control composition preferably comprises a pheromone or parapheromone, for example, a volatilisable sex attractant. Any natural product chemical present in the pest control composition preferably comprises an essential oil or its constituents.
The pest control device may be constructed in any suitable form, for example it may be spherical, polygonal, tubular or collar-shaped. The degradable material may be suspendable or suspended from a support means or may be of a shape suitable for aerial dispatch and distribution.
A plurality of pest control devices may be provided, which are suitable shaped, preferably disc- shaped, and are stackable within a container which may also be degradable, thereby eliminating littering of the environment.
The degradable material may also further comprise a lure and/or a cover for diverting rainwater therefrom and may also be coloured to optimise pest attraction, for example, yellow.
In use of the degradable pest control device, any pest contacting the degradable material may be contaminated with the pest control material and if the pest control material is removed from the surface of the degradable material, by, whatever means, it can be replaced by further degradation of the degradable material and release of more pest control material .
A second aspect of the invention provides a method for controlling pests, comprising releasing from a degradable material a pest control material incorporated therewith.
The degradable material is preferably in the - form of a matrix which is most preferably solid.
Degradation of the degradable' material results in release of the pest control material from an outer surface thereof. This is advantageous because the pest control material is lost at only the surface of the degradable material, as it becomes freed from the degradable material, such as a matrix thereof. In this way, any pest control material, for example, a powder, which is removed by wind, rain or any other extraneous force, is continuously replaced.
The degradable material may comprise any suitable material but preferably comprises a photodegradable polymer, biodegradable polymer, starch-based polymer, hydrolysable polymer, silicon- based polymer or a micro-porous material, for example, an aerogel or any combination thereof.
The degradable material may also comprise an lipophilic material, an oil or any other lightly adhesive material. These substances coat the pest control material which is released at the surface of, say, a matrix, to form particles which may adhere to the cuticle of a pest. Any such particles are preferably of a size less than 50 microns.
The pest control material incorporated with degradable material preferably comprises a powder which may be an electrostatically-chargeable powder, for example, a wax, such as a natural wax, or a plastics polymer, or metallic particles, such as a magnetic powder.
The pest control material most preferably further comprises a pesticide, insecticide, rodenticide, pathogenic fungal spore, entomopathogenic bacilli, semiochemical, natural product chemical or behaviour modifying chemical or any combination thereof. Any behaviour modifying chemical present in the pest control composition preferably comprises a pheromone or parapheromone, for example, a volatilisable sex attractant. Any natural product chemical present in the pest control
composition preferably comprises an essential oil or its constituents.
The degradable material may be constructed in any suitable form, for example, it may be spherical, polygonal, tubular or collar-shaped. The degradable material may be suspendable from a support means or may be of a shape suitable for aerial dispatch and distribution.
Also, a plurality of pest control devices may be provided, which are suitably shaped, preferably disc shaped, and which are stackable within a container which may also be degradable, to eliminate littering of the environment.
The degradable material may also further comprise a lure and/or a cover for diverting rainwater therefrom and may also be coloured, for example, yellow, to optimise pest attraction.
In use of the degradable pest control device, any pest contacting the degradable material may be contaminated with pest control material released therefrom. If the pest control material is removed from the surface of the degradable material, by whatever means, it can be replaced by further degradation of the degradable material.
The degradable material may be designed such that it is aerially distributable.
The invention also provides apparatus for controlling pests, which comprises a pest control device in accordance with the first aspect of the invention defined above, as well as any modifications therefor, as referenced above.
For example, the pest control apparatus may include a container in which one or more devices are accommodated. Such a container may accommodate a stack of pest control devices which are capable of being dispatched and distributed aerially.
The container may be degradable and the apparatus may further comprise a lure and, optionally, a cover for diverting rainwater from the pest control device (s).
A third aspect of the invention resides in a method of making a device for use in controlling pests, which method comprises incorporating with a degradable material a pest control material.
The degradable material may comprise any suitable material but preferably comprises a photodegradable polymer, biodegradable polymer, starch-based polymer, hydrolysable polymer, silicon- based polymer or a micro-porous material, for example, an aerogel or any combination thereof.
The degradable material may also comprise an lipophilic material, an oil or any other lightly adhesive material. These substances coat the pest
control material which is released at the surface of, say, a matrix, to form particles which may adhere to the cuticle of a pest. Any such particles are preferably of a size less than 50 microns.
The pest control material incorporated with degradable material preferably comprises a powder which may be an electrostatically-chargeable powder, for example, a wax, such as a natural wax, or a plastics polymer, or metallic particles, such as a magnetic powder.
Also, the pest control material may further comprise a pesticide, insecticide, rodenticide, pathogenic fungal spore, entomopathogenic bacilli, semiochemical, natural product chemical or behaviour modifying chemical or any combination thereof.
When the pest control material is a behaviour modifying chemical, preferably comprises a pheromone or parapheromone which, in turn, may comprise a volatilisable sex attractant. Any natural product chemical present in the pest control composition preferably comprises an essential oil or constituents thereof.
The degradable material, for example, in the form of a matrix, incorporated with the pest control material, may be formed in any suitable shape but is preferably formed in a shape of a sphere, polygon, tube, collar or disc.
In order that the various aspects of the invention can be more fully understood, preferred embodiments thereof will now be described by way of example only and with reference to the following drawings in which:
Figures 1A and IB are respective diagrammatic side and end views of a first embodiment;
Figure 2 is a side elevation of a second embodiment;
Figure 3 is side elevation of third embodiment ; and
Figure 4 is side elevation of fourth embodiment .
Referring firstly to Figures 1A and IB of the drawings, there is shown a first embodiment of apparatus, indicated generally at 1, for controlling pests, including a plurality of disc-shaped pest control devices 4 each comprising a solid matrix 2 of a degradable material incorporating a pest control material 5.
The devices 4 are stacked within a tubular container 6 and can be dispatched from an aircraft at appropriate locations over an area where pest control is required, by operation of a solenoid-operated piston 8.
Each pest control device 4 is made by mixing the pest control material 5 in the form of an electrostatically-chargeable powder, for example, a wax, such as a natural wax, or plastics polymer, with the degradeable material in the form of a photodegradable polymer, such that the electrostatically-chargeable powder is trapped within the resulting solid, photodegradable polymer matrix 2. Once dispatched into the area where pest control is required, a layer 10 of the electrostatically- chargeable powder 5 forms at the surface of the matrix 4, as the matrix 2 degrades under the action of sunlight. This powder 5 is also formulated with a volatile pheromone or parapheromone or other sex attractant of the species of pest to be controlled.
The powder 5, therefore, acts to attract males of the pest species, to the devices 4. The pests become coated with the powder 5 from the surface layer 10, which adheres to the pests' bodies electrostatically. The powder 5 continues to release the pheromone or parapheromone, causing an interference with the odour-based orientation system by which the males locate females. Mating is thus prevented and population reduction is achieved. Further contaminated males act as mobile dispensers releasing the female pheromone and divert non- contaminated males searching for females. Also males releasing female pheromones tend to be rejected by females ready to mate.
As the pest control powder 5 is removed from the surface layer 10 of the degradable matrix 2, either by contact with a pest or by other mechanical effects, such as wind or rain, it is replaced by photo-degradation of the underlying surface by its exposure to sunlight once more.
Figure 2 illustrates a second embodiment of pest control apparatus in which a pest control device 14 again comprises a degradable solid matrix 12 which, in this case, is spherical. The matrix 12 is made in a similar manner to the matrix 2 of the device 4 of Figures 1A and IB. However, it is formed from a hydrolysable polymer which breaks down on exposure to moisture. In this embodiment, the degradable polymer matrix 12 containing the pest control material in the form of an electrostatically-chargeable powder 15, breaks down at the surface under the influence of moisture, to provide a layer 20 of the powder 15. Exposure of the matrix surface to dew or high humidity is therefore sufficient to maintain a constant surface layer 20 of powder 15.
The device 14 is suspended ' from a suitable support 17, such as a branch, by a plastics-coated wire 18 which supports a lure 16, to attract the desired pest, and a cover 19, which is shaped to divert rainwater away from the device 14. The cover 19 has struts 13 extending downwardly therefrom, which support a receptacle 11 arranged such that it can retain any powder 15 which is dislodged from the matrix 12. The matrix 12 of the device 14 coloured
yellow, which assists in attracting pests, in particular the Mediterranean fruit fly, to the pest control device 14.
This second embodiment is particularly useful for controlling horticultural or crop pests, such as the Mediterranean fruit fly which attacks citrus fruits. The electrostatically-chargeable powder 15 in this embodiment comprises a slow-acting insecticide which acts topically. When a pest lands on the matrix 12 of the device 14, it is contaminated with powder 15 at the surface layer 20, which adheres to the body of the pest. The slow acting insecticide in the powder 15 will cause the pest to die after a period of several days. Before dying, the pest will pass on the powder 15 to other pests during mating and male aggregations prior to mating.
This embodiment may also be made with polyvinyl butyrate, a biopolymer which is completely biodegradable as a result of bacterial action. The polymer material consists of crystalline microspherules . During bacterial degradation these spherules will split into smaller elements, forming a fine dust which is picked up by insects walking on the surface of the polymer or attempting to land on it. In this embodiment the polymer also contains pheromone introduced in a suitable solvent which is later evaporated off. This allows the particles produced by biodegradation to liberate pheromone continuously.
Figure 3 illustrates a third embodiment of pest control apparatus wherein a degradable matrix 22 of a pest control device 24 is polygonal in shape and is placed within a suitable casing 26 to restrict access to children, animals and non-target organisms. The matrix 22 is formed in the same manner as that in Figure 2, namely, from a hydrolysable polymer which degrades under the action of moisture, to release a layer 30 of electrostatically-chargeable powder 25.
In this embodiment, the electrostatically- chargeable powder 25 is also formulated with fungal spores of the entomopathogen Metarhyzium anisopliae.
Pests which enter the casing 26 seeking refuge or attracted by food items placed therein, will come into contact with the surface layer 30 of the matrix 22 and carry away with them the pathogenic fungal spores attached to the electrostatically-chargeable powder 25. Again, these spores may be passed on to further pests where they then germinate on the pests, causing them to die.
Figure 4 shows a fourth embodiment of pest control apparatus comprising a pest control device 34 which is suitable for controlling rodents 40. The apparatus is in the form of interconnecting tubes, with an entry tube 50 of a diameter sufficient to allow the passage of a rodent 40 into a second, outer tube 36 of the device 34.
The entry tube 50 is constructed from a material which will generate an electrostatic charge on the rodent's fur as it passes through the entry tube 50.
The second, outer tube 36 has an inner coaxial tube 38 fitted inside it, which tube 38 is constructed from a electrostatically-chargeable powder formulated with a rodenticide and incorporated with a hydrolysable, degradable matrix 32. The inner surface of the inner coaxial tube 38 is coated with a layer 60 of the powder which has been released from the matrix 32 due to the hydrolysable effect of the humidity within the tube 38 upon that matrix 32.
The fur of the rodent 40, having a temporary electrostatic charge thereon, picks up the powder of the layer 60 containing the rodenticide. On grooming itself, the rodent will ingest the powder, thus leading to its death.
Also, the preferred embodiments described above, could easily be modified, within the scope of the invention, to provide a pest control device and/or associated apparatus which is suitable for use with flying forest pests such as Lepidoptera including, but not limited to, Gypsy moth, Pine processionary moth and Pine shoot moth, Coleoptera including, but not limited to, bark beetles and longhorn beetles horticultural and crop pests, such as, moths and bugs which attack grapes, apples, peaches, olives, cotton, maize, rice, and wheat and public health and amenity
U
pests, such as, flour moths, grain beetles, cockroaches, ants, termites, houseflies, blowflies, tsetse flies and mosquitoes.
Further, the matrix can be formed in other suitable shapes for controlling parasitic arthropods such as ticks, mites and fleas on farm or companion animals. For example, a collar or part of a collar may be formulated to release artropocidal powder into the coat of the animal. The design of the matrix of the pest control device can also be chosen to aid the distribution process and any protective casing used could take a variety of forms.
It will be obvious to a skilled person that magnetic powders can be used in the place of electrostatically-chargeable powders. Also, the active ingredients in the embodiments shown can be substituted to include any synthetic pesticide, biological insecticide, pheromones, parapheromones or other semiochemicals, natural product chemicals such as essential oils or their constituents, or any other compound which can block the action of pheromones, parapheromones or other semiochemicals or any combinations thereof.
Semiochemicals, for example, interfere with pheromone perception or with location of hosts. For example, a female fruit moth is attracted to a source of powder containing fruit odours. The powder on her body that is releasing the odour saturates her antennal sense organs so that she is unable to locate
ripe fruit upon which to lay her eggs. At the same time she will act as a decoy for other egg-laying females .
Pesticides may also be used in conjunction with semiochemicals such as pheromonal attractants and host attractants. In such cases the pesticide chosen has delayed activity. Insects are attracted to a source of powder by pheromonal or other attractants. They become contaminated with the powder which they transfer to other insects in mating attempts or when aggregating in refuges, so spreading the insecticide in the population. By forming the attractant together with the pesticide in the matrix from which the powder is produced, the efficacy of control is improved because the contaminated insects will attract other insects to them, even for a period after their death
It will also be obvious to a skilled person that the degradation rate of the degradable material, such as a matrix, can be determined by modifying its construction. For example, the rate of degradation of starch-based polymers in a given environment can be determined by adjusting the proportion of starch in the polymer. The rate of degradation in photodegradable polymers can also be influenced by the addition of photosensitive promoters.
Further it will be obvious that the size of the powder or particles produced by degradation will affect the probability of them adhering to the insect
body. Particles that are too massive will easily be shed and particles which are too small will carry little active ingredient. A preferred size range is therefore between one and 50 microns, but this may vary.