RODENT BAIT PACKAGE

Abstract: A rodent bait package comprising a quantity of a rodenticide bait composition contained in a package characterised in that the package is made of a material which has a bittering agent or repellent incorporated and/or has a surface layer of a bittering agent or repellent, whereby the bittering agent or repellent deters non-target species from consuming the rodenticide bait composition without deterring the target rodent species.

Description: RODENT BAIT PACKAGE The present invention relates to a rodent bait package useful in preventing accidental ingestion by non-target species. Rodenticide baits were originally formulated on food baits such as whole grains, fine meals, flours and coarse meals. Such baits are very • attractive to granivorous birds and this problem is largely overcome by binding the finely milled grains into a solid matrix with wax. The grains in the wax block are not recognisable by birds. Another method of reducing the hazard is to present the bait, for example a wax block, inside a package or bait station which is accessible to the rodent but not to birds or other animals or humans. However, restricted access is disadvantageous as the rodents prefer open access to food materials. Accidental ingestion of rodenticides by humans, particularly children, and companion animals, particularly dogs, is still a hazard albeit considerably reduced by careful baiting techniques. It is known to use a bittering agent in rodenticide baits in order to repel a non-target animal but not the rodent. GB 2213724 discloses the use of denatonium benzoate in a composition which repels cats, dogs, birds and insects. RD 287020 discloses the use of denatonium benzoate in a rodenticide bait to reduce the palatability to humans and non-target animals. It also discloses that denatonium benzoate can increase the palatability to rats and mice of the rodenticide bromodialone. No evidence of this effect is presented. Denatonium benzoate is known by the trade name Bitrex . A review is given in Chemistry and Industry, 21 November 1988, p721-723. Rodents are known to be deterred by between 100 and 300 ppm of Bitrex, humans are deterred by 10 ppm of Bitrex and dogs are deterred by greater than 100 ppm of Bitrex. Commercially available solutions of Bitrex for preventing dogs from chewing articles (for example Chewguard ) contain from 125-650 ppm. The wide range of application rates indicates that different varieties of dogs are more easily repelled than others. Therefore, in a rodenticide bait containing sufficient Bitrex to ensure deterrence of a dog it is probable that the rodent will also be deterred to a certain extent. It is also known to package bait compositions e.g. whole grains, wax blocks etc, in dosage bags or place-packs. Such packages are useful for * indicates a registered trademark preventing contamination of the operator, for placing a pre-measured dose of the rodenticide or for throwing into a place frequented by rodents which is difficult to access by the operator. The problem is to present sufficient bittering agent or repellent in a bait package containing rodenticide to ensure repellence of non-target animals without affecting the palatability of the bait to the rodent. Thus, according to the present invention there is provided a rodent bait package comprising a quantity of a rodenticide bait composition contained in a package, characterised in that, the package is made of a material which has a bittering agent or repellent incorporated and/or has a surface layer of a bittering agent or repellent, whereby the bittering agent or repellent deters non-target species from consuming the rodenticide bait composition without deterring the target rodent species. Rodent species are sensitive to certain materials in baits and are sensitive to the bittering agents which are commonly added to rodenticide baits. It has now been found to be possible to separate the material to which the rodent is sensitive from the bait to which it is attracted with the consequence that there is less chance of the rodent being deterred from eating the bait. It is a feature of rodent species that they are able to separate out the mechanisms of gnawing and tasting. This is because in the mouth of the rodent there is a large gap between the gnawing (incisor) and chewing (molar) teeth, called the diastema. When gnawing, rodents habitually separate with their cheeks, their incisor teeth from the taste receptors on their tongues, making use of the diastema between their incisor and molar teeth. Therefore, rodents are able to gnaw through articles which are extremely unpalatable to them in order to reach food materials which are palatable. Therefore, in the present invention, the bittering agent which the rodents find unpalatable has been placed in and/or on a packaging material surrounding the bait, so that in use, the rodent gnaws through the packaging material without tasting the bitter agent and obtains access to the palatable rodenticide bait which it consumes by chewing. This ability means that a greater level of bittering agent or repellant can be used in or on the packaging material than was previously used in the rodenticide bait composition. Other vulnerable non-target species, for example, companion animals and non-rodent wildlife, do not have this ability and are deterred by taking the package into their mouths. This invention is suitable for use with any rodenticide. In particular the following anticoagulant rodenticides are mentioned, for example, brodifacoum, bromadiolone, difenacoum, flocoumafen, . chlorophacinone, diphacinone, difethialone, warfarin, coumachlor, coumafuryl, pindone, valone, coumatetralyl. This invention could also be used with acute poisons, for example, bromethalin, flupropadine, zinc phosphide, calciferol, cholecalciferol, antu (alpha-napthylthio-urea) , alpha-chloralose, crimidine, fluoro-acetamide, sodium fluoroacetate, norbormide, scillirocide, strychnine and thallium sulphate. The bait compositions can be any of the conventionally used compositions provided the packaging material is suitable for that composition for example, meals or flours, whole or broken cereal grains, granules, pellets, briquettes, tablets, wax blocks and wax pellets, pastes, gels, greases and liquid formulations. If the rodenticide is formulated as a meal or flour, the packaging is suitably of a material which does not fragment as this may leave particles of bitter agent in the bait. A liquid formulation must obviously be packaged in a liquid tight package. The amount of rodenticide in the bait composition is the conventional amount which varies according to the type of rodenticide. Typically, this is 5ppm to lOOppm of an anticoagulant bait. The bait composition itself may contain a bittering agent at a level palatable to rodents. Therefore, in a further aspect of the invention there is provided, a rodent bait package as defined herein in which bittering agent or repellent is also incorporated in the rodenticide bait. Suitable materials for packaging include conventional packaging materials for foodstuffs, such as plastics, fabrics, laminates and paper such as those used for packaging bread or tea (i.e. tea-bags). For example, wool, linen, cotton, cardboard, polythene, cellophane, metal foils and laminates of two or more of these materials. The material may be vapour permeable. The choice of material is important since once packed the bait may have a shelf life of up to 2-3 years and the bait held within should not become contaminated during this time with the bittering/ repellent agent. Examples of suitable substances as bittering agents are, for example, denatonium benzoate (Bitrex), denatonium saccharide (Vilex), bitter apple extracts, quinine, quinones and phenols, quassin, brucine, bitter aloes and sucrose octaacetate. Bittering agents may be naturally occurring or synthetic. Examples of suitable substances as repellents are 2,4,6-trichlorophenol, amyl acetate, cinnam ' ide derivatives such as those disclosed in EP-A-373909 and alkyl isothiocyanate. The amount of bittering agent or repellent in the package required to achieve the effect is from 100 to lOOOppm, more particularly from 200 to 800ppm, especially 300 to 700ppm. Wherever bittering agent is referred to in this specification it is to be understood to include repellent. In addition to the bittering agent other additives may also be used in the packaging. For example, emetics such as triazolopyrimidines, ipecacuanha, and sodium tripolyphosphate; stenching agents such as ethyl mercaptan, aversive agents, for example, bird aversive agents such as the dyes, natural gentian extract, cochineal, madder and cinnamide derivatives as disclosed in EP-A-321208. The packaging may be prepared by any of the conventional packaging techniques in rodenticide bait technology or in foodstuff technology. The bait compositions are prepared in the conventional manner. The packaging material may have the bittering agent added during manufacture or the material may be impregnated using a solvent carrier. In these cases the bittering agent is integral with the packaging material. Alternatively, the packaging material may be dipped in or sprayed with the bittering agent so that the packaging material has the bittering agent on one or both sides. In a further alternative the packaging material may be printed with an ink containing bittering agent, for example Bitrex. The packaging material enclosing the bait composition may be in the form of, for example, an envelope, sachet, box, capsule, tube, bag, blister pack, carton or pouch. The package usually contains between lg and lOOOg of rodenticide bait composition, typically from 5g to 500g. The rodent bait package may be used against a wide range of rodents pests, including the following commensal species, Rattus species, particularly Rattus norvegicus (Norway rat), Rattus Rattus (Brown rat) Rattus argentiventer (Cotton rat); Mus species, particularly Hus musculus (House mouse); as well as non-commensal species which occur particularly as pests of agricultural crops or stored produce in various parts of the world, such as for example voles of the family Cricetidae including Micro us spp. such as M. agrestis, and Arivicola spp. such as A. terrestris, rats and mice of the family Muridae, including Apodemus spp. such as A. sylvaticus, Acomys caharinus, Akodon spp., Arvicanthis nilotica, Holochilus braziliensis, Mastomys natalensis, Mus booduga, Mus platythrix, Neotoma spp., Peromyscus spp., Rattus exulans, Rattus meltada, Rattus tiomanicus, Sigmodon hispidus and other rodents such as Nesokia indica, Tatera indica, Spermophilus spp. , Meriones spp. , Eutamias spp. , Citellus spp., Bandicota spp., Cricetus cricetus, Ondatra zibetheca, and Myocastor coypus, although this is not intended to be an exhaustive list. In use, one or more of the rodent bait packages are placed at a locus frequented by rodents. The rodent gnaws through the package to the rodenticide bait composition un-deterred by the bittering agent or repellent, whereas non-rodent species are deterred from touching or consuming the package by the bittering agent or repellant, and thereby deterred from consuming the rodenticide bait composition. Therefore, in a further aspect of the invention, there is provided a method of preventing consumption of a rodenticide bait composition by non-target species comprising supplying a rodent bait package containing a quantity of rodenticide bait composition to a locus frequented by rodents characterised in that the package is made of a material which has a bittering agent or repellent incorporated and/or has a surface layer of a bittering agent or repellent, whereby the bittering agent or repellent deters non-target species from consuming the rodenticide bait composition without deterring the target rodent species. The invention is illustrated by reference to, but is not limited by, the following examples which demonstrate rodent bait packages containing rodenticide bait compositions and that rodents are not deterred by high levels of bittering agents or repellent when presented according to the present invention. The skilled operator will appreciate that any of the rodenticides specified herein could be used in the following examples. EXAMPLE 1 This Example illustrates rodenticidal compositions according to the invention. A. Rodenticide bait containing brodifacoum at 0.005% w/w (i.e. 50ppm) formulated as Klerat pellets. 20g of rodenticide bait pellets contained in a sachet made of paper dipped in Bitrex at 600ppm. B. Rodenticide bait containing brodifacoum at 0.0025% w/w (i.e. 25ppm) formulated as Klerat pellets. 30g of rodenticide bait pellets contained in a sachet made of paper impregnated in Bitrex at 600ppm. C. Rodenticide bait containing difenacoum at 0.005% w/w (i.e. 50ppm) formulated as Ratak pellets. 20g of rodenticide bait pellets contained in a sachet made of paper dipped in Bitrex at 500ppm. D. Rodenticide bait containing difenacoum at 0.0025% w/w (i.e. 25ppm) formulated as Klerat pellets. 40g of rodenticide bait pellets contained in a sachet made of paper- dipped in Bitrex at 700ppm. E. Rodenticide bait containing flocumafen at 0.005% w/w (i.e. 50ppm) formulated as Storm wax briquette. 20g of rodenticide wax briquette contained in a carton made of cardboard printed with Bitrex ink at 600ppm. F. Rodenticide bait containing flocumafen at 0.005% w/w (i.e. 50ppm) formulated as Storm pellets. 25g of rodenticide pellets contained in a sachet made of paper/plastic laminate printed with Bitrex ink at 600ppm. G. Rodenticide bait containing difethialone at 0.005% w/w (i.e. 50ppm) formulated as conventional cereal based pellets. 20g of rodenticide bait pellets contained in a sachet made of paper impregnated with Bitrex at 600ppm. H. Rodenticide bait containing brodifacoum at 0.001% w/w (i.e. lOppm) formulated as wax pellets. 20g of rodenticide bait pellets contained in a sachet made of paper impregnated with Bitrex at 600ppm. I. Rodenticide bait containing brodifacoum at 0.005% w/w (i.e. 50ppra) formulated in a conventional broken grain formulation. 20g of rodenticide broken grain formulation contained in a sachet made of paper/plastic laminate, printed with Bitrex ink at 600ppm. J. Rodenticide bait containing brodifacoum at 0.005% w/w (i.e. 50ppm) formulated in a conventional whole grain formulation. 20g of rodenticide whole grain formulation contained in a sachet made of paper/plastic laminate, printed with Bitrex ink at 600ppm. K. Rodenticide bait containing brodifacoum at 0.005% w/w (i.e. 50ppm) formulated as Klerat wax pellets. 20g of rodenticide bait pellets contained in a sachet made of metal foil paper sprayed with Bitrex at 800ppm. L. Rodenticide bait containing brodifacoum at 0.005% w/w (i.e. 50ppm) formulated as Klerat wax block. 250g of rodenticide wax block contained in a carton made of plastic impregnated with Bitrex at 650ppm. M. Rodenticide bait containing brodifacoum at 0.005%w/w (i.e. 50ppm) formulated as a tracking powder. 20g of rodenticide bait pellets contained in a sachet made of polythene impregnated with Bitrex at 600ppm. N. Rodenticide bait containing warfarin at 0.025% w/w (i.e. 250ppm) formulated in a conventional broken grain formulation. 50g of rodenticide broken grain .formulation contained in a sachet made of paper/plastic laminate, printed with Bitrex ink at 600ppm. 0. Rodenticide bait containing brodifacoum at 0.005% w/w (i.e. 50ppm) formulated in a gel formulation. 25g of rodenticide gel formulation contained in a sachet made of paper/plastic laminate, impregnated with Bitrex at 600ppm. EXAMPLE 2 The objective of this experiment was to determine the acceptance by rodents of Bitrex treated rodenticide bait packages. The packages were made of a paper/plastic laminate with the paper forming the external component of the laminate. The packages were diped in a solution of 650ppm Bitrex until the paper was visibly saturated. Two groups of rats (CD Norway Rat) and two groups of house mice (Mus usculus-Swiss) were used in this experiment. Each group contained five male and five female rodents. One group of each of the rats and mice were given rodenticide bait packages containing "Klerat" pellets with Bitrex impregnated into the external layer of the package. The remaining two groups were given untreated rodenticide bait packages. The packages were given to each group over a period of 3 days. Results are given in Table 1. Table 1 There was no significant difference between the acceptance of the Klerat rodenticide bait in the bait bags with or without Bitrex incorporated in the bag for either the mouse or rat. These results demonstrate that rodents are not significantly deterred from eating the bait contained in the packages of the present invention by high levels of bittering agent (i.e. greater than 300 ppm) on or in the packaging material.

Claims: CLAIMS 1. A rodent bait package comprising a quantity of a rodenticide bait composition contained in a package characterised in that the package is made of a material which has a bittering agent or repellent incorporated and/or has a surface layer of a bittering agent or repellent, whereby the bittering agent or repellent deters non-target species from consuming the rodenticide bait composition without deterring the target rodent species. 2. A rodent bait package according to claim 1 wherein the rodenticide bait contains an active ingredient selected from the group of brodifacoum, bromadiolone, difenacoum, flocoumafen, chlorophacinone, diphacinone, difethialone, warfarin, coumachlor, coumafuryl, pindone, valone, coumatetralyl, bromethalin, flupropadine, zinc phosphide, calciferol, cholecalciferol, antu (alpha-napthylthio-urea), alpha-chloralose, crimidine, fluoro-acetamide, sodium fluoroacetate, norbormide, scillirocide, strychnine and thallium sulphate. 3. A rodent bait package according to claim 1 or 2 wherein the bittering agent is selected from the group of denatonium benzoate, denatonium saccharide, bitter apple extracts, quinine, quinones, phenols, quassin, brucine, bitter aloes and sucrose octaacetate. 4. A rodent bait package according to any of the preceding claims wherein the repellant is 2,4,6-trichlorophenol, amyl acetate, a cinnamide derivative or alkyl isothiocyanate. 5. A rodent bait package according to any of the preceding claims wherein the amount of bittering agent or repellent in and/or on the package material is from 100 to lOOOppm. 6. A rodent bait package according to any of the preceding claims wherein the package material is also provided with an emetic and/or a stenching agent and/or an aversive agent. 7. A rodent bait package according to any of the preceding claims wherein bittering agent or repellent is also incorporated in the rodenticide bait. 8. A rodent bait package according to any of the preceding claims wherein the packaging material is formed of one or a combination of more than one of the materials selected from plastics, fabrics, laminates, paper, wool, linen, cotton, cardboard, polythene, cellophane, metal foils and paper/plastic laminates. 9. A method of preventing consumption of a rodenticide bait composition by non-target species comprising supplying a rodent bait package containing a quantity of rodenticide bait composition to a locus frequented by rodents characterised in that the package is made of a material which has a bittering agent or repellent incorporated and/or has a surface layer of a bittering agent or repellent, whereby the bittering agent or repellent deters non-target species from consuming the rodenticide bait composition without deterring the target rodent species.

Inventors: BUCKLE ALAN PETER, BUCKLE, ALAN, PETER
Applicants: ICI PLC, IMPERIAL CHEMICAL INDUSTRIES PLC
Application year: 1992
Main classification: A01N25
IPC codes: A01N25