GB2059771A - Pesticidal compositions - Google Patents

Abstract

The invention relates to pesticidal compositions. There are provided pesticidal compositions comprising (a) the compound of formula <IMAGE> and (b) a pyrethroid insecticide having the general formula <IMAGE> wherein A is an optionally-substituted alkyl, cycloalkyl or arylaminoalkyl group, R is hydrogen, cyano or ethynyl, X is alkyl, alkenyl, aralkyl or aryloxy and n is 1 to 5, their preparation, and their use in combating pests. Compositions according to the invention exhibit surprising synergistic pesticidal activity against aphids such as Aphis fabae, the black bean aphid.

Description

SPECIFICATION Pesticidal compositions This invention relates to pesticidal compositions, their prepartion and their use.

0,0-Diethyl S - (2 - chloro -1 - phthalim idoethyl)phosphorodithioate, i.e. the compound of formula

commonly referred to as "dialifos" ("dialifor" in USA), is described, together with its use as a nonsystemic insecticide and acaricide, in UK Patent Specification No. 1,091,738.

A class of insecticides commonly referred to in the art as "pyrethroid insecticides" is also known and various examples of pyrethroid insecticides are described, together with their preparation, in UK Patent Specification No. 1,413,491 and US Patent No.

3,835,178.

It has now been discovered that mixtures of dialifos and certain pyrethroid insecticides exhibit surprising synergistic activity against aphids such as Aphis fabae, the black bean aphid.

The present invention provides a pesticidal composition comprising (a) dialifos, i.e. the compound of formula I above, and (b) a pyrethroid insecticide having the general formula

wherein A is an optionally-substituted alkyl, cycloalkyl or arylaminoalkyl group, R is hydrogen, cyano or ethynyl, X is alkyl, alkenyl, aralkyl or aryloxy and n is 1 to 5.

An alkyl, cycloalkyl or alkenyl group represented by A or X preferably contains up to 6 carbon atoms, and an araylkyl, arylaminoalkyl or aryloxy group represented by A or X preferably contains up to 12 carbon atoms.

It should be understood that the compound of the general formula II may be present in the form of any one of its optical or geometric, for example cis-trans, isomers, or in the form of a mixture of isomers, for example a racemate. A mixture of two or more compounds according to the general formula II may be present The compound of formula I may also be present in the form of an optical isomer or a mixture of isomers, for example the racemate.

When A represents an optionally-substituted cycloalkyl group, it preferably represents a cyclopropyl group of general formula:

wherein Ra and Rb both represent an alkyl group having from 1 to 6 carbon atoms, especially a methyl group, or a halogen atom, especially a chlorine, bromine or fluorine atom; or Ra and Rb together represent an alkylene group having from 2 to 6, especially 3, carbon atoms; or Ra represents a hydrogen atom and Rb represents an alkenyl group having from 2 to 6 carbon atoms, especially an isobutenyl group, a haloalkenyl group having from 2 to 6 carbon atoms and from 1 to 3 chlorine and/or bromine atoms, especially a monochlorovinyl, monobromovinyl, dichlorovinyl or dibromovinyl group or a haloalkyl group having from 2 to 6 carbon atoms and from 2 to 5 chlorine and/or bromine atoms, especially a tetrachloroethyl, tetrabromoethyl or dibromodichloroethyl group; or a Ra and Rb together with the interjacent carbon atom represent an unsaturated carbocyclic ring system of up to 12 carbon atoms, especially an indenylidene group; Rc and Rd both represent an alkyl group having 1 to 6 carbon atoms, especially a methyl group; or Rc and Rd together represent an alkylene group having from 2 to 6, especially 3, carbon atoms.Preferably Ra and Rb both represent a methyl group or a chlorine atom, or Ra and Rb together represent an alkylene group containing 3 carbon atoms, or Ra represents a hydrogen atom and Rb represents an isobutenyl group, a monochlorovinyl, monobromovinyl, dichlorovinyl or dibromovinyl group or a tetrachloroethyl, tetrab romoethyl or dibromodichloroethyl group; or Ra and Rb together with the interjacent carbon atom represent an indenylidene group; and Rc and Rd both represent methyl groups or Rc and Rd together represent an alkylene group containing 3 carbon atoms.

When A represents an optionally-substituted arylaminoalkyl group, it preferably represents a substituted anilinomethyl group of general formula:

wherein r and f each independently represents a halogen, preferably chlorine, atom, or an alkyl or haloalkyl group of 1 to 4 carbon atoms, for example a trifluoromethyl group, and Q' represents an alkyl group of 1 to 6 carbon atoms, especially a branched chain group, for example an isopropyl group. Preferably Y is a chlorine atom in the 2-position on the benzene ring and f is a trifluoromethyl group in the 4-position on the benzene ring.

Preferablyn represents 1 and X represents a Certain of The Chemical formula(e) appearing in the printed specification were submitted after the date of filing, the formula(e) originally submitted being incapable of being satisfactorily reproduced. phenoxy or a benzyl group, especially a 3-phenoxy or3-benzyl group.

The most preferred pyrethroid insecticides for use in the pesticidal composition according to the invention have the general formula I wherein A is 2,2,3,3tetramethylcyclopropyl, 2- (2,2- dichlorovinyl) - 3,3 dimethylcyclopropyl, or 2 - (2,2 - dibromovinyl) - 3,3 dimethylcyclopropyl; R is hydrogen or cyano; and n is 1 and X is 3-phenoxy. Especially preferred are the compounds known as cypermethrin, permethrin and decamethrin whose formulae are given in the Examples herein.

The weight ratio of the pyrethroid insecticide to dialifos is preferably in the range from 5:1 to 1:500, conveniently to 1:100, and more preferably from 1:1 and conveniently to 1:50.

The mixture of dialifos and the pyrethroid insecticides produces a surprising synergistic effect, for example with respect to aphids, such as Aphis fabae, the black bean aphid. The invention therefore also provides a method of combating pests at a locus which comprises applying to that locus a pesticidal composition according to the invention.

The pesticidal composition according to the invention preferably also comprises a carrier, especially at least two carriers, at least one of which is a surfaceactive agent.

The invention also provides a process for preparing a pesticidal composition which comprises bringing a compound of formula I and a pyrethroid insecticide of formula II into association with at least one carrier therefor.

A carrier in a composition according to the invention is any material with which the active ingredient is formulated to facilitate application to the locus to be treated, which may for example be a plant, seed or soil, orto facilitate storage, transport or handling.

A carrier may be a solid or a liquid, including a material which is normally gaseous but which has been compressed to form a liquid, and any of the carriers normally used in formulating pesticidal compositions may be used.

Suitable solid carriers include natural and synthetic clays and silicates, for example natural silicas such as diatomaceous earths; magnesium silicates, for example talcs; magnesium aluminium silicates, for example attapulgites and vermiculites; aluminium silicates, for example kaolinites, montmorillonites and micas; calcium carbonate; calcium sulphate; synthetic hydrated silicon oxides and synthetic calcium or aluminium silicates; elements, for example carbon and sulphur; natural and synthetic resins, for example coumarone resins, polyvinyl chloride, and styrene polymers and copolymers; solid polychlorophenols; bitumen; waxes, for example beeswax, paraffin wax, and chlorinated mineral waxes; and solid fertilisers, for example superphosphates.

Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones, for ex ample acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic or araliphatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for exam ple kerosine and light mineral oils; chlorinated hydrocarbons, for example carbon tetra-chloride, perchloroethylene and trichloroethane. Mixtures of different liquids are often suitable.

Pesticidal compositions are often formulated and transported in a concentrated form which is subsequently diluted by the user before application. The presence of small amounts of a carrier which is a surface-active agent facilitates this process of dilution.

A surface-active agent may be an emulsifying agent, a dispersing agent of a wetting agent; it may be non-ionic or ionic. examples of suitable surfaceactive agents include the sodium or calcium salts of polyacrylic acids and lignin sulphonic acids; the condensation products of fatty acids or aliphatic amines or am ides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohol or alkyl phenols, for example p-octylphenol orp-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or sulphonates of these condensation products; alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric orsulphonic acid esters containing at least 10 carbon atoms in the molecule, for example sodium lauryl sulphate, sodium secondary alkyl sulphates, sodium salts of sulphonated castor oil, and sodium alkylaryl sulphonates such as sodium dodecylbenzene sulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions of the invention may for example for formulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols.

Wettable powders usually contain 25, 50 and 75% w of active ingredient and usually contain, in addition to solid inert carrier, 3-10% w of a dispersing agent and, where necessary, 0-10% w of stabil iser(s) and/or other additives such as penetrants or stickers. Dusts are generally formulated as a dust concentrate having a similar composition to that of a wettable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing 2-10% w of active ingredient.

Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676 - 0.152 mm), and may be manufactured by agglomeration or impregnation techniques. Generally, granules will contain 2-25% w active ingredient and 0-10% w of additives such as stabilisers, slow release modifiers and binding agents. Emulsifiable concentrates usually contain, in addition to a solvent and, when necessary, co-solvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of other additives such as stabilisers, penetrants and corrosion inhibitors. Suspension concentrates are usually compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-75% w active ingredient, 0.5-15% w of dispersing agents, 0.1-10% w of suspending agents such as protective colloids and thixotropic agents, 0-10% w of other additives such as defoamers, corrosion inhibitors, stabilisers, penet rants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be present dissolved in the formulation to assist in preventing sedimentation or as antifreeze agents for water.

Aqueous dispersions and emulsions, for example compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the present invention. The said emulsions may be of the water-in-soil or of the oil-in-water type, and may have a thick 'mayonnaise'-like consistency.

The compositions of the invention may also contain other ingredients, for example, other compounds possessing pesticidal, herbicidal orfungici- dal properties or attractants, for example phermones or food ingredients, for use in baits and trap formula tions.

The following examples illustrate the invention.

Examples 1 to 3 Activity ofpyrethroidldialifos mixtures against Aphis fabae (black bean aphid) The coefficients of co-toxicity of cypermethrin, permethrin and decamethrin with dialifos were assessed by the following method.

Test solutions or suspensions were made up in water containing 0.4% by weight active ingredient, 20% by weight acetone and 0.05% by weight Triton X-100 (Trade Mark). These solutions or suspensions were subsequently diluted to produce compositions containing various concentrations of active ingredient.

Pairs of leaves were removed from broad-bean plants and placed ventral side uppermost on filter paper inside petri dishes. The leaves were sprayed with the test solution using a logarithmic spraying machine and a dosage equivalent to 400 litres/hectare, and allowed to dry for 2-1 hour. Each leaf pair was infested with 10 aphids. Temperature was held constant at23aC t 2"C, and humidity and lightfluc- tuated. The number of dead and moribund insects was counted after 24 hours. From the results, the LCso (the lethal dosage in percentage by weight required to kill 50% of the test insects) was calculated.

Toxicity indices were then calculated using the following equation:- Toxicity Index (T.l.) = LC50 of ethyl parathion (standard) LC > o Index LC0 of test compound The joint action of the two active components of a mixture was analysed by the method of Yun-Pei Sun and E. R. Johnson, Journal of Economic Entomology, 1960, Volume 53, No. 5, pages 887-892.

Thus, the joint action of two pesticides were analysed by determining the actual toxicity indices of the components and of mixtures of the compounds by references to dosage-mortality curves. The theoretical toxicity of the mixture is equal to the sum of toxicity indices calculated from the percentage of each component multiplied by its respective toxicity index. Therefore, the joint toxicity or Co-toxicity coefficient of a mixture Actual toxicity index of a mixture Theoretical toxicity index of a mixture A coefficient of a mixture near 100 indicates probability of similar action by the two pesticides; independent action usually should give a coefficient less than 100, while a coefficient significantly above 100 strongly indicates synergism.

Cypermethrin, the pyrethroid insecticide used in Example 1, hastheformula:

Permethrin, the pyrethroid insecticide used in Example 2, has the formula

Decamethrin, the pyrethroid insecticide used in Example 3, has the formula

(1 R-cis-S isomer) The results of the Examples are given in Tables I to Ill following: Table I

Compound or Weight Ratio LCso Coefficient Compound Mixture of Mixture % wt of solution of Co-toxicity cypermethrin 1 0.00086 dialifos 0.043 cypermethrin/di alifos 1::25 0.010 143 ethyl parathion 0.0034 Table II

Compound or Weight Ratio LC50 Coefficient Compound mixture of Mixture % wt of solution of C-toxicity permethrin 0.0023 dialifos 0.043 permethrin/ 1:10 0.013 121 dialifos ethyl parathion 0.0034 Table 111

Compound or Weight Ratio LC50 Coefficient Compound mixture of Mixture % wt of solution of Co-toxicity decamethrin 0.00016 dialifos 0.043 decamethrin/ 1: :100 0.0093 123 dialifos ethyl parathion 0.0034 The coefficients of co-toxicity in Tables I to Ill indicate synergism in the mixtures tested.

Claims (17)

1. A pesticidal composition comprising (a) the compound offormula

and (b) a pyrethroid insecticide having the general formula

wherein A is an optionally-substituted alkyl, cycloal kyl or arylaminoalkyl group, R is hydrogen, cyano or ethynyl, X is alkyl, alkenyl, aralkyl or aryloxy and n is 1 to 5.

2. A composition according to Claim 1 wherein A in the compound offormula ll represents a cyclop- ropyl group of formula

wherein Ra and Rb both represent a methyl group or a chlorine atom, or Ra and Rb together represent an alkylene group containing 3 carbon atoms, or Ra represents a hydrogen atom and Rb represents an isobutenyl group, a monochlorovinyl, monobromovinyl, dichlorovinyl or dibromovinyl group ortetrachloroethyl, tetrabromoethyl or dibromodichloroethyl group, or Ra and Rb together with the interjacent carbon atom represent an indenylidene group, and Rc and Rd both represent methyl groups or R0 and Rd together represent an alkylene group containing 3 carbon atoms.

3. A composition according to Claim 1 or 2 wherein in the compound of formula ll n is 1 and Xis a 3-phenoxy group.

4. A composition according to Claim 1 wherein A in the compound of formula II is 2,2,3,3 tetramethylcyclopropyl, 2 - (2,2 - dichlorovinyl) - 3,3 dimethylcyclopropyl, or 2 - (2,2 - dibromovinyl) - 3,3 dimethylcyclopropyl; R is cyano; n is 1 and X is 3-phenoxy.

5. A composition according to Claim 4 wherein the compound of formula II is cypermethrin.

6. Acomposition according to Claim 4 wherein the compound of formula II is permethrin.

7. A composition according to Claim 4 wherein the compound of formula II is decamethrin.

8. A composition according to any one of Claims 1 to 7 wherein the pyrethroid insecticide and the compound offormula I are present in the composition in relative amounts by weight in the range 5:1 to 1:500.

9. A composition according to Claim 8 wherein the relative amounts by weight are in the range 1:1 to 1:100.

10. Acomposition according to Claim 1 substantially as hereinbefore described with particular referpence to Example 1.

11. A composition according to Claim 1 substantially as hereinbefore described with particular reference to Example 2 or 3.

12. A process for preparing a pesticidal composition according to any one of Claims 1 to 11 which comprises bringing a compound of formula I as defined in Claim 1 and a pyrethroid insecticide of formula II as defined in Claim 1 into association with at least one carriertherefor.

13. A process according to Claim 12 substantially as hereinbefore described with particular reference to Example 1.

14. A process according to Claim 12 substantially as hereinbefore described with particular reference to Example 2 or 3.

15. A method of combating pests at a locus which comprises applying to the locus a pesticidal composition according to any one of Claims 1 to 11.

16. A method according to Claim 15 substantially as hereinbefore described with particular reference to Example 1.

17. A method according to Claim 15 substantially as herein before described with particular reference to Example 2 or3.