IE920061A1 - Acaricidal compositions - Google Patents

Abstract

Novel pesticides containing the active substance combination comprising the compounds clofentezine and diafenthiuron display a synergistic improvement of action. The pesticides are mainly employed for controlling pests from the order of the Acarina.

Description

Acaricidal compositions The present invention relates to novel pesticidal compositions for controlling representatives of the order Acarina, which compositions contain a combination of pesticides as active ingredient, and to the use of said combination for controlling pests of the order Acarina which infest plants and animals.

At the present time it is becoming ever more difficult to control pests of the phylum Arthropoda. The principal factors here are the resistance of the pests to the pesticides used for controlling them as well as the concomitant increase in the pesticide concentrations because of the impact on the environment thereby caused. To avoid detrimental consequences for the environment it is therefore necessary to seek a reduction in the concentrations of chemical pesticides. This objective is, however, countered by the fact that the use of lower concentrations of pesticides promotes the development of resistant species of pests and, in addition, ±at there is no guarantee of totally destroying pest populations and their development stages.

To avoid these shortcomings it is therefore desirable to provide compositions for controlling pests, especially acarids, which compositions are sufficiently effective when used in low concentrations and which neither promote resistance nor constitute a hazard to the environment.

A pesticidally active compound frequently used in practice for controlling acarids is clofentezine of formula I (I).

The use of this pesticide has led in the past to the development of resistance in the treated acarid strains. Hence there is a need to provide a pesticidal composition which is highly -2effective against acarids when applied in low concentrations. In particular, there is a need to provide such compositions which are also effective against resistant strains of the order Acarina.

Surprisingly, this need is met by the pesticidal combination of this invention.

Specifically, the invention postulates controlling pests of the order Acarina with a composition which contains a synergistic combination of the compound 3,6-bis(2chlorophenyl)-l,2,4,5-tetrazine (clofentezine) of formula I and of the compound N-tert-butyl-N'-(2,6-diisopropyl-4-phenoxy)phenylthiourea (diafenthiuron) of formula II The compounds of formulae I and Π are described in the literature, together with processes for their preparation, for example in EP-A-5 912 and GB-PS 2 060 626. Both compounds are also commercially available under the registered trademarks APOLLO® and POLO®.

The pesticidal combination of this invention is used for controlling different pests of the order Acarina which infest plants and animals, either by using a combination formulation in which both components are applied simultaneously, or by applying both compounds of formulae I and II in succession at brief intervals. It is also possible to apply the compounds by using a so-called tank mixture, which is prepared by formulating a combined dilute spray mixture of the individually formulated compounds of formulae I and II. However, to ensure the safety and effectiveness of application it is convenient to use a combined formulation of both compounds which need only be diluted with water by -3the end user to the desired concentration.

When using the combination of compounds of formulae I and II in the practice of this invention an unexpected synergistic enhancement of activity is observed. In particular, a synergistic enhancement of activity is also observed against those pests which have developed resistance to clofentizine.

The pesticidal combination of this invention will preferably be used against ticks and also mites which attack plants and animals. To be singled out for special mention is the excellent action against phytopathogenic mites. Crops in which phytopathogenic mites, especially spider mites, occur as important pests are ornamentals as well as crops of useful plants such as cotton, vegetables and fruit. The pesticidal combination of compounds of formulae I and II is highly effective against all development stages of the treated mites. Both the adult pests and the different larval stages and the eggs are destroyed.

In the practice of this invention, the compounds of formulae I and II are combined with each other in application or in the combination formulations in such weight ratios that, in the combined action of the components, the biological effects are synergistically enhanced. Normally the weight ratios of the compounds of formulae I and II are in the range from 100:1 to 1:100. Preferred mixture ratios are from 50:1 and 1:20, more particularly from 20:1 to 1:20 and, most preferably, from 5:1 to 1:5. Preferred concentrations in the application suspensions are, for combined application, normally from 10 to 60 g of active substance per 1001 of ready-for-use suspension. A preferred range is one in which 20 to 40 g of active compound mixture is applied per 100 1 of suspension. For application in crops of useful plants, from 50 to 1000 g of active compound mixture is applied per hectare, preferably from 100 to 450 g/ha. For application in animal hygiene in the productive livestock sector, the ready-for-use suspensions are also typically used for cattle dips, in spray races, for pour-on applications and for hand-spray and hand-dressing applications.

The novel compositions are especially suitable for controlling pests of animals and plants, as they meet the stringent requirements for this utility particularly well. They are distinguished by the following properties: - low lethal minimum concentration for pests, especially for resistant forms - low toxicity to humans and productive livestock - uniform duration of action over several months -4- no problems with residues.

The importance of this invention also resides in the feature that the novel compositions can be successfully used against ticks and mites and thus make a significant contribution to maintaining the health of humans and animals by preventing the outbreak of diseases. Furthermore, the use of the novel compositions in agriculture substantially enhances the yield of productive livestock and useful plants.

The novel combinations of the compounds of formulae I and Π are normally applied together with the carriers and/or adjuvants conventionally employed in the art of formulation, and are therefore formulated in known manner to emulsifiable concentrates, directly sprayable or dilutable solutions, dilute emulsions, wettable powders, soluble powders, dusts, granulates, and also encapsulations in e.g. polymer substances. As with the compositions, the methods of application such as spraying, atomising, dusting, scattering or pouring, are chosen in accordance with the intended objectives and the prevailing circumstances.

The formulations, i.e. the compositions, preparations or mixtures containing the combinations of compounds of formulae I and 2 and, where appropriate, a solid or liquid adjuvant, are prepared in known manner, e.g. by homogeneously mixing and/or grinding the active ingredients with extenders, e.g. solvents, solid carriers and, in some cases, surface-active compounds (surfactants).

Suitable solvents are: aromatic hydrocarbons, preferably the fractions containing 8 to 12 carbon atoms, e.g. xylene mixtures or substituted naphthalenes, phthalates such as dibutyl phthalate or dioctyl phthalate, aliphatic hydrocarbons such as cyclohexane or paraffins, alcohols and glycols and their ethers and esters, such as ethanol, ethylene glycol, ethylene glycol monomethyl or monoethyl ether, ketones such as cyclohexanone, isophorone or diacetone alcohol, strongly polar solvents such as N-methyl-2-pyrrolidone, dimethyl sulfoxide or dimethyl formamide or water, vegetable oils such as rapeseed oil, castor oil, coconut oil or soybean oil; or also silicone oils.

The solid carriers used e.g. for dusts and dispersible powders are normally natural mineral fillers such as calcite, talcum, kaolin, montmorillonite or attapulgite. To improve the physical properties it is also possible to add highly dispersed silicic acid or highly dispersed absorbent polymers. Suitable granulated adsorptive carriers are porous types, for -5example pumice, broken brick, sepiolite or bentonite; and suitable nonsorbent carriers are materials such as calcite or sand. In addition, a great number of pregranulated materials of inorganic or organic nature can be used, e.g. especially dolomite or pulverised plant residues.

Suitable surface-active compounds are non-ionic, cationic and/or anionic surfactants having good emulsifying, dispersing and wetting properties. The term surfactants will also be understood as comprising mixtures of surfactants.

Suitable anionic surfactants can be both water-soluble soaps and water-soluble synthetic surface-active compounds.

Suitable soaps are the alkali metal salts, alkaline earth metal salts or unsubstituted or substituted ammonium salts of higher fatty acids (C10-C22), e.g. the sodium or potassium salts of oleic or stearic acid, or of natural fatty acid mixtures which can be obtained, e.g. from coconut oil or tall oil. Further suitable surfactants are also the fatty acid methyltaurin salts.

More frequently, however, so-called synthetic surfactants are used, especially fatty sulfonates, fatty sulfates, sulfonated benzimidazole derivatives or alkylarylsulfonates.

The fatty sulfonates or sulfates are usually in the form of alkali metal salts, alkaline earth metal salts or unsubstituted or substituted ammonium salts and generally contain a Cg-C22alkyl radical which also includes the alkyl moiety of acyl radicals, e.g. the sodium or calcium salt of lignosulfonic acid, of dodecylsulfate, or of a mixture of fatty alcohol sulfates obtained from natural fatty acids. These compounds also comprise the salts of sulfated and sulfonated fatty alcohol/ethylene oxide adducts. The sulfonated benzimidazole derivatives preferably contain 2 sulfonic acid groups and one fatty acid radical containing about 8 to 22 carbon atoms. Examples of alkylarylsulfonates are the sodium, calcium or triethanolamine salts of dodecylbenzenesulfonic acid, dibutylnaphthalenesulfonic acid, or of a condensate of naphthalenesulfonic acid and formaldehyde. Also suitable are corresponding phosphates, e.g. salts of the phosphated polyadduct of 4 mol of p-nonylphenol with 14 mol of ethylene oxide, or phospholipids.

Non-ionic surfactants are preferably polyglycol ether derivatives of aliphatic or cycloaliphatic alcohols, or saturated or unsaturated fatty acids and alkylphcnols, said -6derivatives containing 3 to 30 glycol ether groups and 8 to 20 carbon atoms in the (aliphatic) hydrocarbon moiety and 6 to 18 carbon atoms in the alkyl moiety of the alkylphenols. Further suitable non-ionic surfactants are the water-soluble adducts of polyethylene oxide with polypropylene glycol, ethylenediaminopolypropylene glycol and alkylpolypropylene glycol containing 1 to 10 carbon atoms in the alkyl chain, which adducts contain 20 to 250 ethylene glycol ether groups and 10 to 100 propylene glycol ether groups. These compounds usually contain 1 to 5 ethylene glycol units per propylene glycol unit.

Representative examples of non-ionic surfactants are nonylphenolpolyethoxyethanols, castor oil polyglycol ethers, polypropylene/polyethylene oxide adducts, tributylphenoxypolyethoxyethanol, polyethylene glycol and octylphenoxypolyethoxyethanol. Fatty acid esters of polyoxyethylene sorbitan, e.g. polyoxyethylene sorbitan trioleate, are also suitable non-ionic surfactants.

Cationic surfactants are preferably quaternary ammonium salts which contain, as N-substituent, at least one C8-C22alkyl radical and, as further substituents, unsubstituted or halogenated lower alkyl, benzyl or hydroxy-lower alkyl radicals. The salts are preferably in the form of halides, methylsulfates or ethylsulfates, e.g. stearyltrimethylammonium chloride or benzyl bis(2-chloroethyl)ethylammonium bromide.

The surfactants customarily employed in the art of formulation are described e.g. in the following publications: Me Cutcheon’s Detergents and Emulsifiers Annual, Me Publishing Corp., Glen Rock NJ USA, 1988, H. Stache, Tensid-Taschenbuch (Surfactants Manual), 2nd. ed., C. Hanser Verlag Munich/Vienna 1981, M. and J. Ash. Encyclopedia of Surfactants, Vol. I-III, Chemical Publishing Co., New York, 1980-1981.

The pesticidal compositions usually contain 0.1 to 99 %, preferably 0.1 to 95 %, of the combination of compounds of formulae I and II, 1 to 99.9 % of a solid or liquid adjuvant, and 0 to 25 %, preferably 0.1 to 25 %, of a surfactant. -7Whereas commercial products are preferably formulated as concentrates, the end user will normally employ diluted formulations of substantially lower concentration.

Preferred formulations are composed in particular of the following constituents (% = percentage by weight): Emulsifiable concentrates active compound mixture: surfactant: liquid carrier: to 90 %, preferably 5 to 20 % 1 to 30 %, preferably 10 to 20 % to 94 %, preferably 70 to 85 % Dusts active compound mixture: solid carrier: 0.1 to 10 %, preferably 0.1 % 99.9 to 90 %, preferably 99.9 to 99 % Suspension concentrates active compound mixture: water: surfactant: Wettable powders active compound mixture: surfactant: solid carrier: Granulates active compound mixture: solid carrier: to 75 %, preferably 10 to 50 % 94 to 24 %, preferably 88 to 30 % to 40 %, preferably 2 to 30 % 0.5 to 90 %, preferably 1 to 80 % 0.5 to 20 %, preferably 1 to 15 % 5 to 95 %, preferably 15 to 90 % 0.5 to 30 %, preferably 3 to 15 % 99.5 to 70 %, preferably 97 to 85 %.

The compositions can also contain further ingredients such as stabilisers, typically vegetable oils or epoxidised vegetable oils (epoxidised coconut oil, rapeseed oil or soybean oil), anlifoams such as silicone oil, preservatives, viscosity regulators, binders, tackifiers and fertilisers or other chemical agents to obtain special effects.

The invention is illustrated by the following non-limitative Examples.

Example FI: Wettable powders a) b) c) mixture of compounds I and II (1:1) 25 % 50% 75 % sodium ligninsulfonate 5 % 5 % - sodium laurylsulfate 3 % - 5 % sodium diisobutylnaphthalenesulfonate - 6 % 10% octylphenol polyethylene glycol ether (7-8 mol of ethylene oxide) - 2 % - highly dispersed silicic acid 5% 10% 10 % kaolin 62% 27 % - The combination of active ingredients is thoroughly mixed with the adjuvants and the mixture is thoroughly ground in a suitable mill, affording wettable powders which can be diluted with water to give suspensions of any desired concentration.

Example F2: Emulsifiable concentrate mixture of compounds I and II (5:1) 10 % octylphenol polyethylene glycol ether (4-5 mol of ethylene oxide) 3 % calcium dodecylbenzene sulfonate 3 % castor oil polyglycol ether (36 mol of ethylene oxide) 4 % cyclohexanone 30 % xylene mixture 50 % Emulsions of any required concentration can be obtained from this concentrate by dilution with water.

Example F3: Dusts mixture of compounds I and II (50:1) talcum kaolin a) b) % 8 % % % Ready for use dusts are obtained by mixing the compound mixture with the carrier, and grinding the mixture in a suitable mill. -9Example F4: Extruder granulate mixture of compounds I and II (1:5) 10 % sodium ligninsulfonate 2 % carboxymethyl cellulose 1 % kaolin 87 % The compound mixture is mixed and ground with the adjuvants, and the mixture is subsequently moistened with water. The mixture is extruded, granulated and then dried in a stream of air.

Example F5: Coated granulate mixture of compounds I and II (1:1) 3% polyethylene glycol 200 3 % kaolin 94 % The finely ground compound mixture is uniformly applied, in a mixer, to the kaolin moistened with polyethylene glycol. Non-dusty coated granulates are obtained in this manner.

Example F6: Suspension concentrate a) b) c) mixture of compounds I and II (1:2) 40 % 50 % 60 % ethylene glycol 10% 10 % 8 % nonylphenol polyethylene glycol ether (15 mol of ethylene oxide) 6% 6 % 5 % sodium ligninsulfonate 10 % 10% 5 % carboxymethyl cellulose 1 % 1 % 1 % silicone oil in the form of a 75 % aqueous emulsion 1 % 1 % 1 % water 32 % 22 % 20% The finely ground compound mixture is homogeneously mixed with the adjuvants, giving a suspension concentrate from which suspensions of any desired concentration can be obtained by dilution with water. -10Biological Examples Example BI: Action against Tetranychus urticae Bean plants in the 2-leaf stage are each populated with 5 adult females of two strains of Tetranychus urticae which are resistant to clofentezine. 24 hours after infestation, the plants are sprayed in a spray cabinet to drip point with aqueous suspensions of the individual compounds clofentazine and diafenthiuron and of mixtures of these compounds in concentration series. The test plants are then cultivated in a greenhouse at +25°C/60 % relative humidity and in daylight for 14 hours per day. Evaluation is made 14 days later by brushing the bean leaves and making a count of the living mobile stages of the subsequent generations of the test organisms. Using the untreated control for comparison purposes, the percentage mortality rate of the pest population is determined for the individual compounds and for the mixture as a function of the concentration of the active ingredient.

Test results: Active ingredient Tetranychus urticae Strain: SCHERING-ROSEN (Clofentezine-resistant) Cone, [ppm] Mortality [%] Comp. I 3000 36 4000 46 6000 38 8000 66 16000 68 Comp. II 5 0 10 0 20 9 50 28 100 69 200 77 400 79 1:2 mixture 3.7 0 of I and II 7.5 7 15 32 30 50 60 71 - ii - Active ingredient Tetranychus urticae Strain: SCHERING-APFEL (Clofentezine-resistant) Cone, [ppm] Mortality [%] Comp. I 1500 24 3000 21 4000 56 8000 75 16000 71 Comp. II 5 9 10 37 20 32 40 34 50 60 100 95 400 99 1:2 mixture 3.7 0 of I and Π 7.5 0 15 41 30 60 60 79 The concentration-mortality curves are computed from these values by means of the Probit analysis according to D.J. Finney (Probit Analysis, 2nd. Edition, Cambridge University Press, 1952). The LD50 values (concentration which effects 50 % mortality of the test population) for the individual compounds as well as for the compound combinations can be read off from these curves: LD50I and LD50II.

Evaluation: With the aid of these LD50 values, the potentiation rate (PR) is determined as reference value for the synergism which occurs using the Cotox formula according to L. Banki (Bioassay of Pesticides in the Laboratory Research and Quality Control, p. 313, Akaddmia Kiadd, Budapest, 1978).

The potentiation rate (PR) is given by the following quotient: /\ LD50 ld50 • 12In the denominator, the LD50 is the value determined for the toxicological test of the z\ compound combination, whereas the numerator LD50 denotes the expected value of the combination which is obtained from the following equation: ld50-μ I μ II - + ld50i ld50ii The values μ I and μ II denote the relative proportion of the respective mixture component in the total mixture. The sum of the numerical values μ I and μ II is 1.

PR values greater than 1 indicate potentiation in terms of a synergistic enhancement of the mixture components.

Yield a) Tetranychus urticae (SCHERING-ROSEN strain ) Active ingredient Weight ratio of the mixture ld50 Potentiation rate PR calculated found compound I - - 5940 - compound II - - 93 - mixture of compound I and compound Π 1:2 138.4 30 4.6 - 13Yield b) Tetranychus urticae (SCHERING-APFEL strain) Active ingredient Weight ratio of the mixture Potentiation rate PR calculated found compound I compound Π - - 4820 25 - mixture of compound I and compound II 1:2 44.9 25 1.8

Claims (8)

What is claimed is:

1. A pesticidal composition which contains, in addition to a compound of formula I (I) as second active component, a compound of formula II (II) in an amount sufficient to effect a synergistic pesticidal action

2. A composition according to claim 1, which contains the compounds of formulae I and Π in the weight ratio of 100:1 to 1:100, preferably 50:1 to 1:20, more particularly 20:1 1:20 and, most preferably, 5:1 to 1:5.

3. A method of controlling pests, which comprises treating said pests or the locus thereof with a mixture of the compound of formula I according to claim 1 and of the compound of formula II according to claim 1, which mixture effects a synergistic pesticidal action.

4. A method according to claim 3 for controlling pests of the order Acarina.

5. A method according to claim 4 for controlling phytopathogenic spider mites.

6. A process according to claim 4 for controlling ticks and animal mites, excluding the treatment of the human and animal body. -157. A pesticidal composition according to claim 1, substantially as hereinbefore described and exemplified

7.

8. A method according to claim 3 of controlling pests, substantially as hereinbefore described and exemplified.