United States Patent (19) 11 Patent Number: 4,826,685 Stewart 45 Date of Patent: May 2, 1989
54 MOLLUSCICIDAL DEVICE 2115697 9/1983 United Kingdom . 2119249 11/1983 United Kingdom . 75) Inventor: Ray F. Stewart, Redwood City, Calif. OTHER PUBLICATIONS 73 Assignee: Landec Labs, Inc., Redwood City, Chemical Patents Index, Basic Abstracts Journal, Sec Calif. tion C, Week K04, Abstract No. 08680 K/04, Derwent Publications Ltd., London, GB; & JP-A-57 20300. 21 Appl. No.: 932,444 Chemical Abstracts, vol. 100, No. 11, 12th Mar. 1984, p. 22 Filed: Nov. 17, 1986 170, Abstracts No. 81202a, Columbus, OH, U.S.; J. 51) int. Cl." ...... A01N 25/08: A01M 1/20 IGRC et al. 52 U.S. C...... 424/410; 43/114; Chemical Abstracts, vol. 76, No. 9, Feb. 28th 1972, p. 43/131; 43/136; 424/84; 424/409; 514/481; 101, Abstract No. 42732q. Columbus, OH, US: C. Mal 514/693 let et al. 58) Field of Search ...... 43/114, 136, 131; Primary Examiner-Thurman K. Page 424/405, 409, 419, 416, 407 Attorney, Agent, or Firm-Irell & Manella 56) References Cited 57 ABSTRACT U.S. PATENT DOCUMENTS A molluscicidal device in the form of a chemophysical 1,385,241 3/1974 Grubb et al...... 424/14 barrier which is placed in the path of molluscs (e.g., 2,938,830 5/1960 Davey ...... 424/409 between their habitat and an area to be protected from 3,47, 18 12/1968 Cardarelli...... 424/409 X infestation). The device comprises a solid body, typi 4,007,258 2/1977 Cohen et al...... 424/409 cally in the form of a sheet or continuous length strip 4,198,441 4/1980 Young et al...... 43/136 X made of a thermoplastic water-insoluble polymer in 4,198,782 4/1980 Kydonieus et al. . ... 424/419 X
which is dispersed a molluscicidal agent. The dimen 4,269,820 5/1981 Davies et al...... 424/410 X sions of the body, the nature of the agent, and the con 4,320,113 3/1982 Kydonieus ...... 424/416 centration of the agent on the surface of the body are FOREIGN PATENT DOCUMENTS such as to cause any mollusc that attempts to cross the 1180086 2/1970 United Kingdom. body to be immobilized, whereby it remains on the 1240622 7/1971 United Kingdom . body and receives a lethal dose of the agent. 2074868 11/1981 United Kingdom ...... 424/405 2080687 2/1982 United Kingdom ...... 424/411 20 Claims, No Drawings 4,826,685 1. 2 for them to receive a lethal dose of the agent from the MOLLUSCICDAL DEVICE body. Another aspect of the invention is a molluscicidal DESCRIPTION composition comprising a mixture of: 1. Technical Field (a) a low vapor pressure alcohol, and The invention is in the general field of pesticides. (b) metaldehyde, a carbamate molluscicide, or a mix More particularly it relates to a molluscicidal device in ture of metaldehyde and a carbamate molluscicide. the form of a molluscicidal agent-containing water MODES FOR CARRYING OUT THE insoluble polymeric body that is placed in the path of INVENTION molluscs. The body immobilizes any molluscs that at 10 tempt to traverse the body and transmits a lethal dose of The novel molluscicidal device of the invention pro the molluscicidal agent to the molluscs immobilized on vides a chemophysical barrier to molluscs that (1) is the body. long lasting, (2) may be exposed to environmental mois 2. Background ture (rain, snow, fog, sprinklers, dew) without losing its 15 efficacy (3) places a minimum amount of molluscicidal Various traps, baits and poisons have been used to agent into the environment, (4) is not a danger to mam control populations of land or aquatic molluscs. Metal mals such as children and pets, (5) is easy to position and dehyde, carbamates, and organophosphates are con reposition around the perimeter of plants or planting monly used as molluscicides for land snails. Fudge, F. areas, and (6) can be manufactured in a form that is easy D, and Kuhr, R. J., J Econ Entom, (1972) 65:242-245. 20 to store and handle. Organotin and copper compounds are commonly used A key feature of the molluscicidal device of the in to control aquatic snails, Japanese Pat. Publication No. vention is that it is designed chemically and physically 57-203003 teaches that saturated aliphatic alcohols such to immobilize molluscs that attempt to cross it. Prior as ethanol and butanol or mixtures of ethanol and C8 or devices that have involved the mechanism of pest im Cio alcohols are toxic to snails. 25 mobilization have generally used adhesives to physi Several prior references describe polymer-based for cally entrap the pest. These prior adhesive-based de mulations of molluscicides, French Patent Publication vices (e.g. fly paper) often do not employ pesticidal No. 2,085,181 describes granules of the water-swellable agents and rely solely on immobilization as a means of polymer, polyvinylpyrrolidone, and metaldehyde. U.S. killing the pest. Use of an adhesive is not a feasible way Pat. Nos. 3,417,181, 3,639,583, 3,851,053, 3,928,564, 30 to immobilize snails and slugs for several reasons. First, 4,012,221, and 4,228,614 describeformulations of organ such molluscs do not adhere to conventional water otin or insoluble copper compounds with polymeric based adhesives because they secrete a slime that will binders that are useful as antifouling coatings for sub not stick to such adhesives. Second, the device has to be merged marine structures and for the control of aquatic exposed to environmental moisture which is likely to snails. 35 dissolve or otherwise degrade the adhesive. Finally, an Insecticide-containing polymeric devices in the form adhesive-based device will pickup soil, leaves and other of strips or collars have been used to control insects debris commonly found in the garden or other site of such as flies, roaches and fleas. Representative examples S5. of such products are described in U.S. Pat. Nos. Since the invention device is designed to immobilize 3,318,769, 3,295,246, 3,705,938, 3,857,934, 3,864,468, the snail or slug on the device, it does not have to have and 4,320,113. None of these references mentions mol a high surface concentration of molluscicidal agent. In luscicides and none of them describes a device that this regard, prior nonadhesive based polymeric pestici would be suitable as a toxic barrier to molluscs. dal devices, such as the cockroach strip described in No prior art known to applicant teaches or suggests a U.S. Pat. No. 4,320,113, must have a high surface con molluscicidal device in the form of a solid body of a 45 centration of toxic agent so that the pest is killed as a molluscicide in a water-insoluble thermoplastic poly result of a very sbort contact time with the device. Use mer that has a relatively low surface concentration of of high surface concentrations is not feasible for long molluscicide and acts as a chemophysical barrier to lasting molluscicidal devices since the device must be molluscs by immobilizing any mollusc that attempts to exposed to rain, fog, dew and other environmental cross the body and transmitting a toxic dose of the 50 moisture which would wash the agent from the surface molluscicide to themollusc while it is immobilized on of the device. This would require the device to contain the body. a large reservoir of molluscicide to be long-lived. Place more molluscicide residue in the environment than is DISCLOSURE OF THE INVENTION necessary and pose a greater danger to mammals who One aspect of the invention is a molluscicidal device 55 mightingest the device or a portion of the device. With comprising a body adapted to be placed in the path of regard to mammalian safety, even if the invention de molluscs, said body being made of a water insoluble vice or a portion thereof is ingested, it is likely that the polymer having dispersed therein a molluscicidal agent, device or portion would be excreted before it released a in which the concentration of the agent in the polymer harmful amount of the molluscicide. and the permeability of the polymer to the agent are 60 Both the chemical composition and the structure of such that the body has a low surface concentration of the invention device are important to its efficacy. In the agent. whereby the body is resistant to rapid deple terms of chemical composition, the device is comprised tion of agent due to contact with environmental mois of two basic components: (1) a thermoplastic orthermo ture, and the activity of the agent at said concentration setting water-insoluble polymer in which is dispersed and the smallest pathwise dimension of the body are 65 (2) a molluscicidal agent. The concentration of the mol sufficient to immobilize on the body molluscs that at luscicide in the polymer and the permeability of the tempt to traverse the body, whereby such molluscs are polymer to the molluscicide at normal use temperatures retained in contact with the body for a sufficient time are such that the concentration of molluscicide on the 4,826,685 3 4. surface of the device is low, i.e., less than or equal to immobilize and/or kill molluscs. Such alcohols are gen about 5 mg per square inch. Normally, the concentra erally not toxic to mammals and are typically used in tion of molluscicide on the surface of the device will be cosmetics. The alcohol may be straight-chain or in the range of 0.1 to 5 mg per square inch. Preferably branched-chain. Examples of such alcohols are 2-ethyl the surface concentration will be below about 1 mg per 5 hexanol, n-octanol, decanol, undecanol, dodecanol, square inch. As indicated above, such low surface con tetradecanol, pentdecanol, hexadecanol, and eicosanol. centrations minimize the amount of toxic agent released Many of these alcohols are sold commercially as mix to the environment and reduce the danger to mammals. tures. In addition to low vapor pressure alcohols, minor The polymer will normally be of the dense (nonpo amounts of other materials such as antioxidants and UV rous), hydrophobic type rather than microporous type. 10 stabilizers to help prevent degradation of the polymer, In this regard, microporous polymers would tend to pigments to color the device or protect it from sunlight permit penetration of environmental moisture and degradation, plasticizers to improve the processibility leaching of the molluscicide from the device. Examples of the mixture, and dispersants and surfactants to facili of thermoplastic polymers that may be use to form the tate the mixing of the polymer and molluscicide may device are: polyolefins such as polyethylene, polypro 5 optionally be included in the mixture. pylene copolymers, ethylene-propylene copolymers, The use of combinations of a low vapor alcohol and and ethylene-propylene-diene terpolymers; ethylene either metaldehyde, a carbamate molluscicide, or mix vinyl acetate copolymers of about 5% to about 60% by tures thereof is not limited to the chemophysical barri weight vinyl acetate: poly(vinyl acetate) and other poly ers described above. Such combinations may be used in (vinyl esters); acrylic polymers such as acrylic and 20 conventional formulations such as in granules. wettable methacrylic ester polymers and copolymers, copoly powders, and sprayable liquids (solutions, emulsions, mers of alkyl or alkylene acrylates or methacrylates; suspensions). The weight ratio of alcohol to metal copolymers of ethylene and alkyl acrylates; polybutadi dehyde/carbamate in such combinations (both in the ene and butadiene copolymers such as butadiene-sty chemophysical barrier and in other formulations) will rene-acrylonitrile polymers; polyesters such as polyca 25 usually be in the range of about 1:5 to 5:1, more usually pro lactone, poly(lactic acid), lactic acid-glycolic acid about 1:1 to 2:1. The conventional formulations will copolymers, polyamides such as nylon, polyalkylene include a suitable diluent (solid in the case of solid for oxides such as poly(propylene oxide) and poly(butylene mulations, liquid in the case of liquid formulations) and oxide); polyurethanes; and cellulosics such as cellulose other conventional additives, depending upon the par acetate, cellulose propionate, cellulose butyrate, cellu 30 ticular formulation, such as baits, binders, colorants, lose acetate butyrate and cellulose acetate butyrate surfactants, and the like. propionate. Blends of these polymers may be employed A key functional feature of the physical structure of to obtain desired physical or chemical properties (e.g. the body is that it be (1) shaped so that it may be placed hydrolytic stability, hydrophobicity, softening point, in the path of molluscs to provide an effective barrier viscosity and the like). 35 between the mollusc habitat and the area to be pro Examples of molluscicidal agents that may be used in tected from infestation, and (2) sized so that the smallest the device are metaldehyde, N-naphthyl methylcarba pathwise dimension of the body is sufficient to expose mate, 4-(dimethylamino)-3,5-dimethyl phenol methyl any mollusc attempting to cross the body to an immobi carbamate, 3,5-dimethyl-4-(methylthio)phenol methyl lizing amount of the biologically active agent(s) present carbamate, N-trityimorpholine-5,2-dichloro-4- on the surface of the body. Typically the body will be nitrosalicylanilide, and S-methyl-N-(methylcarbamoyl) shaped as a sheet or continuous strip whose smallest oxythioacetimidate. In this regard, the term "carbamate pathwise dimension (width in the case of a continuous molluscicide' as used herein is intended to include mol length strip) is less than about one-third of a meter and luscicidal oxime carbamates and carbamates. Other normally less than about one-ninth of a meter. In func suitable molluscicides are described by Fudge and 45 tional terms, the smallest pathwise dimension of the Kuhr, supra. Mixtures of one or more of these mollusci body must be at least equal to the "immobilization cides may be used. The molluscicide will usually com length' of the body-the immobilization length being prise about 5% to 25% by weight of the polymer-mol the distance over which a mollusc must travel on the luscicide mixture. The polymer and molluscicide may body for it to receive a dose of the active ingredient(s) be blended together using conventional polymer mixing 50 that causes it to lose the ability to move in a normal equipment such as Henshel mixers, Banbury or Sigma fashion. This length is a function of the immobilization mixers, and roll mills. activity and surface concentration of the molluscicide. The polymer-molluscicide mixture may be formed The snail or slug will thus be immobilized while in into an appropriately shaped body by extrusion, casting, contact with the body and remain in contact with the and the like. Alternatively, the mixture may be com 55 body for a time sufficient to receive (presumably via bined with liquid diluents as a solution, emulsion, or absorption) a lethal dose of the active ingredient(s) on dispersion and be sprayed, painted, doctor-bladed, or the surface of the body. From this discussion it is appar otherwise applied to an appropriate substrate to provide ent that the toxicity of the device is a function of the the devices of the invention. surface toxicity of the body and the time spent on the If the biological activity of a particular molluscicide surface of the body by the mollusc. Immobilization is is such that it is not capable of immobilizing molluscs, accomplished at low surface concentrations of active other molluscicides or agents that either enhance or ingredient(s) by including in the body a molluscicide directly cause immobilization may be added to the mix that is known to effectively immobilize slugs and snails, ture. In this regard, it has been found that low (i.e. less a nerve toxin, or a low vapor pressure alcohol as de than 1 mm Hg at 25° C) vapor pressure alcohols such as 65 scribed above. In this regard, the mode of action of such alkylene glycols and aliphatic alcohols of at least about alcohols is not known and may be due to a toxic or 8 carbon atoms, and preferably 8 to 20 carbon atoms, immobilizing activity of the alcohol itself, an absorption enhance the ability of at least certain molluscicides to promoting activity of the alcohol, or a combination of 4,826,685 5 6 these mechanisms. Reserve toxin/immobilizing agent within the polymer matrix continuously diffuse(s) to the TABLE 1-continued surface to replace materials that are removed from the Formulation A. B C D E F G H surface by molluscs, environmental moisture, debris, or mortality the like. ethylene-vinyl acetate copolymers, 28 wt % vinyl acetate When the body is made in the form of a continuous N-naphthyi methylcarbamate strip it may be desirable to coat one side of the strip with As reported the formulas containing only metalalde an adhesive so that the device can be readily affixed to hyde (A, B, C), Sevin (D) and decanol (E) as active plant stems, plant containers, walkways defining plant ingredients provided no or marginal (F) mortality in ing areas and the like. Strip forms of the device may be 10 these tests. The presence of nonionic surfactant in for easily laid in place about the perimeter of the area to be mulas D and F had no apparent effect as a toxin or as an protected from mollusc infestation and moved, if neces enhancer. In comparison the formulas that contained sary or desirable, to other locations. Further, they may either or both of Sevin and metaldehyde in combination be tied about the stems of plants to protect foliage from with decanol (G and H) provided 100% mortality after mollusc attack. Continuous strip forms of the device are 15 24 hr. Further the immobilization length associated conveniently made in the form of rolls from which the with formulations G and H was dramatically less than user may unravel lengths necessary to protect a given with formulations A-F. 33. The invention is further illustrated by the following VARIATION OF POLYMER, CARBAMATE, examples. These examples are not intended to limit the AND ALCOHOL invention in any manner. The following formulation was prepared: FORMULATION Two part urethane: elastomer (Conap EN-2): 87.5% All ingredients used in making the devices described Lannate (oxime carbamate); 4.4% in the examples were purchased from commercial 25 Metaldehyde: 5.8% sources. The ingredients were blended in a Brabenderin 2-ethylhexanol: 2.3% the indicated proportions (proportions are specified in S-methyl-N-(methylcarbamoyl)oxythioacetimidate weight %, unless indicated otherwise). After blendling The material was mixed thoroughly and degassed to the mixtures were pressed into 6 inx6 in slabs 35 to 45 remove entrapped air, then coated into a thin sheet of mils thick. 30 polyethylene. The material was cured at 50 C. for 1 hr TEST PROCEDURE followed by 6 hr at room temperature. Efficacy testing was carried our as above with the European brown snails (Helix Aspera Muller) were following result: collected and kept in an empty terrarium prior to use. IL = 1 inch Test slabs of the molluscicidal, polymeric formulations 35 24 hr mortality= were rinsed with tap water and blotted dry prior to use. Typically a reactive system (e.g., two part urethane) A snail was placed at the center of the slab and ob such as this would be coated onto a carrier substrate, for served. The distance traveled by the snail after place example, a fabric backing, a cardboard or paper mate ment on the slab was recorded and is referred to as the rial, or other suitable carrier. The system could be used immobilization length (I.L.). After a snail was immobi without a backing if desired. A reactive system such as lized (or moved a total of 12 in) it was transferred to a this could be lised as a paint if desired to provide a clean box for observation. Mortalities were determined field-applied barrier. after 24, 48 and 72 hr. All tests were done in triplicate Similar systems could be readily prepared from vari and immobilization lengths were averaged. 45 ous latex or emulsion systems. Typically these are wa GENERAL EFFICACY TESTS ter-based systems. Such systems must be water resistant once dried. Various formulations of polymers and molluscides were formulated and tested for efficacy. PRODUCT LONGEVITY TESTS The results of these tests are reported in Table 1 The following formulation of ethylene-vinyl acetate below. 50 copolymer, Sevin, metaldehyde and decanol was pre TABLE 1 pared as described above. Formulation A. B C D E F G H Elvax 250 80 - - - 89 90 TO TO 66 Component Wt 9% Poly OOO 93 aaaa- ra- O 55 Elvax 250 64 caprolactone metaldehyde 2 Polyvinyl O 93 O - aa- pre Statex 160 O acetate Sevin 2 Decanol aa- ar 10 O 10 10 Decano O Metaldehyde 10 7 7 10 10 O piperonyi butoxide l Sevin - 5 - - - 2 Tween 202 1. Carbon black 10 Dr. -- 5 10 10 10 Nonionic - 10 w 2 Carbon black surfactant Nonionic surfactant Inmobiliza- >8 > 12 > 12 > 12 > 12 >8 3.8 15 tion Length Two 6 inx6 inx0.035 in slabs were pressed from the (inches) formulation. A 0.05 in thick film of polyethylene was 24-hour 0/3 0/3 0/3 0/3 0/3 1/3 3/3 4/4 laminated to each side of one of the slabs (designated mortality slab A). The two slabs were fastened to a board and 48-hour 0/3 OW3 0/3 Ov3 0/3 1/3 aua placed outdoors. Snails were placed on the slabs period 4,826,685 7 8 ically and tested for immobilization and mortality at 48 TABLE 3-continued hr as above. The results of these tests are reported in Table 2 below. Effect of Surface concentration and Immobilization Surface Exposure 24-hour TABLE 2 5 Test Concentration Time I.L. Mortality Immobilization Slab B 0 mg/in sq' 5 min 2 in. O/3 Length (mortality) A. B C 0 mg/in sq 24 hr 2 in. 4/4 Day 1 4 in.
Formulation 1 2 3 4. 4. 5 6 7 8 Ethanol 2% Isopropanol 2% Decanol 1.5% 1% 9% 1% Sevin 1% 1%. 12, 1% Lannate 0.5% 0.5% Nopacol 4-0 0.3% 0.5% 0.5% Volume (ml) 1 1. 1 O.S 1. 0.5 0.6 0.6 Time T 120 120 120 90 90 90 90 90 90 (min) Mortality O/4 1/7 O/3 1/4 2/6 8/9 3/4 A4 3/3 (24 hr) Sevin was in the form of a 15% commercial solution. The data is shown in Table 3. TABLE 3 The above results show that none of the alcohols Effect of Surface concentration and Inmobilization tested is an effective molluscicide when used in a low Surface Exposure 24-hour 65 concentration spray. Also, the data clearly show that Test Concentration Time I.L. Mortality the carbamates and oxime carbamates tested are not A Freshly prep. 24 h. <1 in. 4/4 effective as low concentration sprays (combined mor A. 5 mg/in sq 5 min < 1 in. O/3 tality=4/13). Combinations of low vapor pressure alco 4,826,685 10 hols and carbamates or oxime carbamates are. however, 7. The device of claim 6 wherein the combination of very effective (combined mortality = 14/16). materials comprises metaldehyde and a carbamate mol Modifications of the above-described modes for car luscicide. 8. The device of claim 7 wherein the carbamate mol rying out the invention that are obvious to those of skill luscicide is N-naphthyl methylcarbamate. in the field of pesticide formulation are intended to be 9. The device of claim 1 wherein the body includes a within the scope of the following claims. material that enhances the ability of the agent to immo I claim: bilize molluscs and/or the toxicity of the agent to mol 1. A molluscicidal device that acts as a chemophysi luscs. cal barrier to terrestrial molluscs and kills terrestrial 10 10. The device of claim 6 wherein the agent is a com molluscs through prolonged physical contact rather bination of an alcohol having a vapor pressure of less than by releasing a molluscicidal agent into the environ than 1 mm Hg at 25 C. and either metaldehyde, a car ment inhabited by the molluscs comprising a body in the bamate molluscicide or mixtures of metaldehyde and a form of a sheet or strip adapted to be placed in the path carbamate molluscicide. 15 11. The device of claim 10 wherein the alcohol is a of terrestrial molluscs, said body being made of a water aliphatic alcohol of at least about 8 carbon atoms. insoluble polymer having dispersed therein a terrestrial 12. The device of claim 11 wherein the alcohol is molluscicidal agent, in which the concentration of the decanol. agent in the polymer and the permeability of the poly 13. The device of claim 10 wherein the carbamate mer to the agent are such that the body has a low sur 20 molluscicide is N-naphthyl methylcarbamate. face concentration of the agent, whereby the body is 14. The device of claim 1 wherein the surface concen resistant to rapid depletion of agent due to contact with tration of the agent is less than about 5 mg/square inch. environmental moisture, and the activity of the agent at 15. A molluscicidal composition comprising a mix said concentration and the smallest pathwise dimension ture of: 25 (a) an alcohol of at least about 8 carbon atoms having of the sheet or strip are sufficient to immobilize on the a vapor pressure of less than 1 mm Hg at 25 C., body terrestrial molluscs that attempt to traverse the and body, whereby such molluscs are retained in contact (b) metaldehyde, a carbamate molluscicide, or a mix with the body for a sufficient time for them to receive a ture of metaldehyde and a carbamate molluscicide. lethal dose of the agent from the body. 30 16. The molluscicidal composition of claim 15 2. The device of claim 1 wherein the agent is a combi wherein the weight ratio of (a) to (b) is in the range of nation of a carbamate molluscicide and caffeine. about 1:5 and 5:1. 3. The device of claim 2 wherein the carbamate mol 17. The molluscicidal composition of claim 15 luscicide is N-naphthyl methylcarbamate. wherein the alcohol is an aliphatic alcohol. 4. The device of claim 1 wherein said dimension is 35 18. The molluscicidal composition of claim 15 wherein the carbamate molluscicide is N-naphthyl me less than about one-third of a meter. thylcarbamate. 5. The device of claim 1 wherein said dimension is 19. The molluscicidal composition of claim 15 less than about one-sixth of a meter. wherein the composition is in the form of a sprayable 6. The device of claim 1 wherein the agent is a combi 40 liquid. nation of materials exhibiting biological activity against 20. The molluscicidal composition of claim 15 molluscs, at least one of the materials having the ability wherein the composition is in a solid particulate form. to immobilize molluscs. is
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