CA1184486A

CA1184486A - Rodenticidal bait

Info

Publication number: CA1184486A
Application number: CA000422330A
Authority: CA
Inventors: Nikolaus Gschwind; Gunter Frerot; Hartmut Spannring
Original assignee: Ciba Geigy Investments Ltd
Current assignee: Novartis AG
Priority date: 1982-02-26
Filing date: 1983-02-24
Publication date: 1985-03-26
Also published as: IE830404L; ATE23418T1; EP0088051B1; MY8600345A; DD207141A5; IE54723B1; GB8304815D0; DE3367500D1; GB2115698B; AU562356B2; DK160788B; MA19730A1; PH19074A; BR8300915A; HU201216B; JPS58157701A; EP0088051A1; GR78115B; ZA831297B; AU1184383A

Abstract

RODENTICIDAL BAIT
Abstract The invention relates to a rodenticidal block bait consisting essentially of brittle-hard polyvinyl acetate, or of a brittle-hard copolymer of vinyl acetate and acrylic acid ester, methacrylic acid ester and/or acrylonitrile, and a foodstuff treated with a rodenticidal poison and dispersed in the polymer carrier. The polymer component (polyvinyl acetate or vinyl acetate copolymer) serves simultaneously as a taste-tempting, hardening and water-resistant constituent in the bait. The invention relates also to a process for producing this block bait from aqueous polymer-dispersions.

Description

Case 5~ 26/+
RODENTICIDAL BAIT
The present invention relates to a rodenticidal block bait, to processes for producing it, and to its use for controlling rodents, par~icularly rats and mice.
The control of rats, mice and other harmful rodents is a problem of primary importance, because these animals are carriers of serious infectious diseases, and they also constitute an enormous loss factor with regard to the role they play in the destruction and contamination of foodstuffs. Within this genus of animals, the commensal rodents, especially the rats, assume a prominent position since they share with man the same environment and also his food resources. The brown rat or water-rat (Rattus norvegicus)~ the house rat (Rattus rattus), the house mouse (Mus musculus), the :Eielcl mouse (Microtus arvalis) and the black water rat (Arvicola terrestris) belong to the most abundant group of rodents.
The rodents, living as tribe animals, have a high level of adaptability and a keen sense of smell. They are provided among themselves, in particular the rats~ with a remarkable warning system. Any success in controlling rodents depends largely on the degree to which their characteristic habits and behaviour patterns are understood.

Mice ard rats take up their food basically in a nonsystematic manner and at random: they rarely keep to one single type of food when a range of different foodstuffs is available. Alone this aspect of their behaviour renders the combating of them difficult.
Poisoned bait is moreover immediately rejected by the rats when they have identifie-l it as such on the basis of taste and compatability. Mass control of rodents hence inevitably results in difficulties when members of the same species connect the death of one of the animals among them with the bait being consumed and thus avoid it.
There have been no shortage of attempts to make bait palatable for rats by means of enticements and taste corrigents, and at the same time to ensure that the poison is not immediately absorbed in the upper gastro-intestinal tract of the rat, where the poison commences to take effect during the actual intake of food, that is to say, prema-turely. It is regularly observed in such cases that the affected rat straight away ceases to eat, and that consequently none of the animals belonging to the same tribe again touches the poisoned bait concerned or any other similar bait.
The subacute rodenticides, particularly the anti-coagulants, at present form, by virtue of their delayed, but certain, action, the most important group of effective preparations. The success of the mass application thereof has however fallen short of expectations.
There still remains therefore the problem of how to obtain rodenticidal compositions specifically designed to take account of the behaviour of the rodent~ in order to ensure greater success.

~ ~4~6 Whereas great attention has been paid to the problem of enticement and flavouring substances, the behavi.our pattern specific to rodents has been studied ~o a far lesser degree with respect to practical application.
The gnawing urge of the rodent is a behaviour characteristic whlch in the formulation of effective types of bait .Eor rodents has been hitherto quite insufficiently taken into account.
The hard paraffin blocks (containing bait) commercially available have shown that they do not, from the polnt of view of taste and consistency, come up to expectations.
Solids with sliding layers (for example hard paraffin), semisolid material and also gel-like substances do not satisfy the material requirements for an effective bait.
It is the object of the present invention therefore to provide, as a rodenticidal preparation, a formed hard bait-block which has a) a sufficient hardness, especially brittle hardness, and b) at the same time a pleasant..taste (palatable), in consequence of which the rodents are induced to continue gnawing and consuming the bait.
It has been shown that this problem can be solved surprisingly quickly and simply by intimately mixing polyvinyl acetate on its own, or copolymers of vinyl acetate and acrylic acid ester~ methacryLic acid ester and/or acrylonitri:le, in an aqueous dispersion, with the desired solid or pasty, edible component of the poison bait; and subsequently casting or shaping the resulting semiliquid mixture into fairly large granules, or preferably into blocks, 4 to looo g in weight, of the shape required, and finally drying the product obtained. In addition to containing the three essential components, namely: polymer, feed-constituent and poison, the block bait according to the ~ ~ 8 ~

invention can contain in small amounts (up to about 10 %
by weight) other additives aclapted to suit the given practical requirements.
The hard bait or block bait which is thus produced using the process according to the invention described in the foregoing, by bonding with polyvinyl acetate or with a copolymer thereof as binder, and which has a weight of between 4-5 and 1000 g, preferably 10 to 100 g, has the following properties simultaneously existing and very desirable for practical application:
1) adequate brittle hardness, which is particularly suitable for gnawing and which is very much liked by wild rats and mice;

2) high level of palatableness, which is the cause, in parti.cular in the case of wild rats, of block bait of this type being clearly preferred to a simiLar feed without an addition of polymer;

3) resistance to water, which can indeed result in a slow (maximum 20%) swelling of the block bait, but which does not impair its firmness, and does prevent.it over a period of several weeks in position from disintegra-ting.
Polymeric substances have already been used in practice as binders for active substances. Thus, the Japanese Published Specification No~ 72/19 199 (Ikari Yakuhin AG) describes the knea~ing of norb.ormide [= 5 (a-hydroxy-a-2-pyridylbenzyl)-7-(a-2-pyridylbenzylidene)-norborn-5-ene-2,3 dicarboximide], in the ratio of about 2:1, with an aqueous polyvinylacetate emulsion, with subsequent fine grinding, filtering out and drying at 80C. The poison powder thus produced is mixed in the ratio of about 1:100 with cereal flour, and in this manner a bait for use in dust form is obtained. The problem to be solved in this case and the results obtained are completely different from those of the present invention. The palatableness which a largish polyvinyl acetate-(Co)polymer constituent induces has not been recognised in the solution suggested in the Japanese Publication any more than has the possibility of producing, together with all auxiliaries~ in a single operation, block bait which satisfies the gnawing urge of rats and mice. Furthermore, the said publication enables no conclusions to be drawn as to a resistance of whatever nature to water.
The present invention relates, in a narrower sense, to a process for producing a firm, gnawable, shaped rodenticidal block bait, 5-1000 g in weight, which process comprises mixing, for 1-60 minutes, 96-70 per cent by weight (relative ]5 to the finished bait) of a previously prepared feed com-ponent, which con~ains, in addition to the poison component of 0.001 - 1.0 per cent by weight, optionally up to 10%
(of its weight) of mineral and vegetable fillers, taste corrigents, microbicides, germination inhibitors, dyes and/or other additives suitable with regard to application technique, with an aqueous dispersion of polyvinyl acetate, or of a copolymer of vinyl acetate with acrylic acid ester, methacrylic acid ester and/or acrylonitrile (which disper-sion constituents, after drying, make up the weight portion of the other components of the mixture to L00%), water being if necessary added, to thus obLain a pourable mixture;
casting or otherwise forming this mixture, with drying, into blocks; and subsequently clrying these at 10-60C.
The air drying of the hardening mixture of the block bait is preferably carried out at room temperature.
For copolymerisation, suitable partners for vinyl acetate are essentially those monomers which produce hard bonds and which with regard to taste are pleasant for rodents. Acrylic acid esters and methacrylic acid esters, the alcoholic components of which are derived from methanol, ethanol, butanol, hydroxyethanol or ethoxy-ethanol, are preferred. Also esters of higher alcoholsgsuch as decyl alcohol and lauryl alcohol, can be used.
Commercial (poly)vinyl acetate dispersions frequently contain up to 5% of other unsaturated compounds, such as acrylic acid, crotonic acid, maleic acid or maleic anhydride, or higher homologues of polyvinyl acetate, such as polyvinyl propionate or polyvinyl butyrate. Such substances which favourably influence the hardening of the polymer for the purpose according to the invention count as copolymer constituents which are concomitantly embraced by the present invention.
Suitable mineral and vegetable additives or extenders are for example: kaolin, talcum, chalk, limestone, Attaclay, dolomite, diatomaceous earth, precipitated silicic acid, alkaline-earth silicates, sodium and potassium aluminium silicates (feldspars and mica), calcium and magnesium sulfates, magnesium oxide, ground plastics, ground vegetable products, such as bark flour, wood flour, nutshell flour or cellulose powder, each on its own or as mixtures with one another.
The feed portion of the block bait can embrace all types of durable solid foodstuffs, preferably storable hard feed, particularly that based on cereals, such as bread and confectionary, flour, cereal grain and whole meal, and also appropriate mixtures thereof. Also suitable however are other types of feed of animal or vegetable origin, such as fish, meat or bone residues, or grape-vine and maize residues, oil cake, dried fruit, fruit peel, and so forth.

~ ~ 8 ~

Further subject matter of the present invention is a rodenticid~l block bait which weighs 4-1000 g, and which consists essentially of brittle-hard polyvinyl acetate, or of a brittle-hard copolymer of vinyl acetate and acrylic acid ester 9 methacrylic acid ester and/or acrylo-nitrile, and also a foodstuff treated with a rode~ticidal poison and dispersed in the polymer carrier.
In general, the polymer component co~stitutes 4-30 %
by weight of the block bait, and the remainder, that is, the feed component (including up to 10 % by weight of possible additives),which makes the total portion up to 100% by weight, contains 0.001 - 1.0 % by weight, pref-erably 0.005 - 0~1 C/D by weight, of poison component.
The polymer component in the block bait amounts preferably to 7-15 % by weight, for example 10 % by weight.
Vinyl acetate copolymers are preferred, and among these the vinyl acetate / acrylic acid-lower alkyl ester copolymers.
Suitable as active ingredients are essentially all known rodenticides, preferably those of the anticoagulant class, such as 4~hydroxycoumarin derivatives, of which the following are preferred:
3-(3-biphenyl-4-yl-1,2,3,4-tetrahydro-1-naphthyl)-4-hydroxycoumarin (Difenacoum)~
3-[3-(4'-bromobiphenyl-4-yl)-1,2,3,4-tetrahydro-l-naphthyl]-

4-hydroxycou~larin (Brodifacoum), 3-[4'-bromobiphenyl-4-yl-3-hydroxy-1-phenylpropyl)-4-hydroxycoumarin ~Bromadiolone), 3-(a-acetonylbenzyl)-4-hydroxycoumarin (Warfarin), 3-(a acetonyl-4-chlorobenzyl)-4-hydroxycoumarin (Cumachlor), 4-hydroxy-3-(192,3,4-tetrahydro-l-naphthyl) coumarin ~Coumatetralyl), and 3-(2-acetonylfurfuryl)-4-hydroxycoumarin (Cumafuryl).
Further preferred active ingredients are the anti-coagulants derived from 1,3-indandione, of which the following are preferred:
2-[2 (4-chlorophenyl)-2-phenylacetyl]-1,3-indandione (Chlorophacinon), 2-dip~enylacetyl-1,3-indandione (Diphacinone) and 2-pivaloyl-1,3-indandione (Pindon).
A further rodenticidal active ingredient which is preferred is 2,4,6-tribromo-N-methyl-2',~'-dinitro-6'-trifluoromethyldiphenylamine (Bromethalin).
The present invention relates also to the use of a rodenticida'L block bait as described in the foregoing for controlling rodents.
Further subject matter of the present invention is a process for controlling rodents, particularly rats and mice, by the administration and putting out of rodenticidal bait as descr:ibed in the foregoing as gnawable block bait.
The production of a particularly preferred preparation is described -in the ~ollowing.
Production Example (to produce 1 kg of dry bait) 900 g of wheat grains, treated with"Cumachlor"(0.01%) and coloured with the food dye "Patentblau V" (0.05%) [Ca salt of 2,4-disulfo-5-hydroxy-4',4"-bis(diethylamino)-triphenylcarbinol anhydride, Colour Index ~2051] are placed into a Hobarth mixer with a 3-litre agitator vessel.
While slow stirring is maintained, 179 g of an approx.
56% aqueous vinyl acetate/acrylic acid butyl ester copolymer dispersion are added, and - depending on the viscosity of the dispersion - also 50-100 ml of water. There is formed, after 2-5 minutes' stirring, a viscous mixture, which is filled into prepared moulds in order to produce therefrom individual bait shapes each weighing 4 35 g and being in any desired form, for example as plates~ cubes, truncated cones, rods, and so forth. The whitish, slightly frothy mixture is air-dried and, as a result of evaporation of the water, the block bait according to the invention is formed in the moulds, this block bait material being trans-paren~ and no longer water-soluble (but still swellable).
"Bromadioloni' or "Bromethalin" can also be very advantageously used in place of "Cumachlor"~ And instead of "Patentblau", any other warning dye suitable for the purpose can be employed.
It is also possible to advantageously use, in place of wheat grains, a coarse meal mixture consisting of:
26.66 % by weight of (oat) groats, 26.67 % by weight of fodder rice, and 26.67 % by weight of wheatmeal (shred), which, prepared in the same manner, is bonded with 20 %
by weight of polyvinyl acetate, or with vinyl acetate/
acrylic acid ester copolymer or vinyl acetate/acrylo-nitrile copolymer.
Biolo~ical Example (feed-bait preference) On two groups of 24 laboratory rats and 24 wild mice, respectively, the inclination of the animals to show prefer-ence for the block bait according to the invention rather than for a similar feed bait without hard bonding with polyvinyl acetate (copolymer) was tested.
a) 12 male and 12 female laboratory rats having body weights of between 174 and 261 g were kept in individual cages each with a wire-mesh bottom. There was siLuated under each cage a collecting tray with filter paper, in order to co'lect parts of feed and bait falling down from the cages and to make it posslble to carry out a re-weighing.
The animals had water available ad libitum from special drinking bottles. There was offered to the animals, beside the drinking bottles, the normal or standard feed, consisting of 1/3 (oat) groats, 1/3 fodder rice and 1/3 wheatmeal (shred), in a container.
The employed block bait according to the present invention, consisting of:
26.66 % by weight of (oat) groats, 26.67 % by weight of ~odder rice, 26.67 % by weight of wheatmeal (shred), and lS 20000 % by weight of a vinyl acetate/ acrylic acid ester copolymer, had a mean weight of 35 g, and dimensions oE 40 x 40 x 30 mm.
The ar~imals had the block bait offered to them in a container fixed to a side wall at right-angles to the 20 drinking bottle. Normal feed and block bait were offered simultaneously during 4 days at 20 + 2C with simulated light (light phase: 13 hours, dark phase: 11 hours). The daily cons~lmption was determined for each individual animal by re-weighing the offered feed. The average amount 25 of feed consumed in 4 days was as follows:
Average amount of Species block bait normal feed .
male rats 73.8 + 10.3 g 52.4 + 9.1 g female rats 69.0 + lO.l g 21.4 + 6.6 g total average amount 71.4 + 10.2 g 36.9 ~ 7.9 g The rats prefer the bLock-bait formulation to the normal feed by the ratio of 2:1. What is moreover striking is the clear 3:1 preference in the case of female rats.
c, b) 24 mice of both sexes (Mus musculus domesticus3, from the second generation of mice caught wild, having body weights of between 18 and 32 g were subjected in their individual cages to the same test as described under a).
After a habituation phase of about one and a half days, 1(J durirlg which the animals disregarded the initially preferred soft feed more and more in favour of the block bait, the average feed intake per day was as follows.

3rd Day 4th Day block bait : soft feed 4.0 1.1 g 4.0 : 0.7 g

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A rodenticidal block bait which weighs 4-1000 g and which consists essentially of brittle-hard polyvinyl acetate, or of a brittle-hard copolymer of vinyl acetate and acrylic acid ester, methacrylic acid ester and/or acrylonitrile, and a foodstuff treated with a rodenticidal poison and dispersed in the polymer carrier.

2. A bait according to Claim 1, wherein the polymer constit-uent amounts to 4-30 per cent by weight, and the poison component is present in an amount of 0.001 to 1.0 per cent by weight, relative to the foodstuff constituent.

3. A bait according to Claim 2, wherein the polymer constit-uent amounts to 7-15 percent by weight.

4. A bait according to Claim 2, wherein the polymer constit-uent amounts to 10 per cent by weight.

5. A bait according to Claim 1, wherein the polymer constit-uent is essentially a copolymer formed from vinyl acetate and acrylic acid ester.

6. A bait according to Claim 2, wherein the poison component is present in an amount of 0.005 - 0.1 per cent by weight, relative to the foodstuff constituent.

7. A bait according to Claim 2, wherein the foodstuff consti-tuent contains up to 10 per cent by weight of other additives selec-ted from the group of mineral or vegetable fillers, taste corrig-ents, microbicides, germination inhibitors and dyes.

8. A bait according to Claim 1, wherein the foodstuff constituent consists of a hard feed based on cereals.

9. A bait according to Claim 1, wherein the rodenticidal poison is selected from the anticoagulant class

10. A bait according to Claim 9, wherein the anticoagulant is a 4-hydroxycoumarin derivative.

11. A bait according to Claim 10, which contains 3-(.alpha.-acetonyl-4-chlorobenzyl)-4-hydroxycoumarin (= Cumachlor).

12. A bait according to Claim 10, which contains 3-[4'-bromobiphenyl-4-yl-3-hydroxy-1-phenylpropyl)-4-hydroxycoumarin (= Bromadiolone).

13. A bait according to Claim 1, wherein the rodenticidal poison is 2,4,6-tribromo-N-methyl-2',4'-dinitro-6'-trifluoromethyldiphenylamine (= Bromethalin).

14. A bait according to Claim 1, which consists of 90 per cent by weight of prepared cereal grain containing 0.01 per cent by weight of "Cumachlor" or "Bromadiolone"
and 0.05 per cent by weight of dye; and 10 per cent by weight of vinyl acetate/acrylic acid ester copolymer.

15. A bait according to Claim 1, which consists of 90 percent by weight of prepared cereal grain containing 0.005 - 0.1 per cent by weight of "Bromethalin"; and 10 percent by weight of a vinyl acetate/acrylic acid ester copolymer.

16. A process for producing a brittle-hard rodenticidal block bait weighing 4 to 1000 g, which process comprises mixing, for 1-60 minutes, the foodstuff constituent, which constituent is ultimately to constitute 96-70 percent by weight of the finished dry bait, and which can contain, besides the poison component of 0.001 - 1.0 per cent by weight, up to 10 per cent by weight (of its own weight) of mineral and vegetable fillers, taste corrigents, microbicides, germination inhibitors, dyes and/or other additives suitable with regard to application technique, with an aqueous dispersion of polyvinyl acetate, or of a copolymer of vinyl acetate and acrylic acid ester, methacrylic acid ester and/or acrylonitrile, water being if necessary added, to thus obtain a pourable mixture; then casting or otherwise forming this mixture into blocks; and subsequently drying these at 10-60°C.

17. A method for controlling rodents, which comprises the administration and putting out of a rodenticidal block bait according to Claim 1.

18. A method according to Claim 17 wherein the rodents are rats and/or mice, and wherein the food component in the block is chosen to be acceptable to rats and/or mice.