GB1602972A - Synergistic pesticidal compositions - Google Patents

Description

(54) SYNERGISTIC PESTICIDAL COMPOSITIONS (71) We, THE WELLCOME FOUNDATION LIMITED, of 183-193 Euston Road, London, N.W.1, a company incorporated in England do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is performed, to be particularly described in and by the following statement:- This invention relates to the new use of pesticidal compositions for the control of pests of the sub-Orders Ixodidae and Sarcoptiformes.

Pyrethroids embranced by formula (I):

are known from U.K. Patent No. 1 413 491 to possess insecticidal activity, and are known from South African Patent No. 3211/1975 to possess acaricidal activity.

Pests of the Class Insecta and of the Order Acarina are troublesome to man, animal and plants. They are vectors of disease, and economic losses result from their depredations on plants and animals. Control of such pests over the years has come to depend strongly upon the use of chemical pesticides which can be naturally occuring compounds or synthetic organic chemicals.

Carbamate pesticides are used in both the agricultural and veterinary fields with varying degrees of success. Some of these substances are common to both fields whilst others have been solely employed in the agricultural field. In recent years resistance to carbamate compounds has evolved in certain strains of Insects and Acarids both of agricultural and veterinary importance and accordingly the need for new, effective insecticides and acaricides has arisen.

It is known from Japanese Patent Publication No. 064422/1975, that potentiation of activity occurs between a pyrethroid of formula (I) and certain carbamates against Insects and certain Mites of agricultural importance. The Japanese publication also suggests that the potentiation is due to the interaction between the inhibition of the enzyme acetyl-cholinesterase by the carbamate compound at the ganglionic junctions of the pest, which results in ganglionic nerve paralysis, and the disturbance of axonal nerve transmittance through the cell membranes of the nerve axons of the pest by the pyrethroid, which results in impaired axonal nerve transmission.

It has now been surprisingly found that there is potentiation between a pyrethroid of formula (I) and certain carbamate compounds against pests of veterinary importance which are resistant to conventional carbamate compounds and which belong to the sub-Orders Ixodidae and Sarcoptiformes. It is believed that the potentiation is due to the inhibition by the carbamate compound of certain esterases which degrade pyrethroids. The various rates at which different groups of arthropod pests, even within the same Order of classification, metabolise a pyrethroid makes it difficult to predict potentiation in one group of arthropod pests from a knowiedge of potentiation in another group.

The pyrethroid for use in the present invention is selected from the esters of formula (I). Structural formula (I) is intended to encompasss all the geometric and optical isomers poossible. More particularly the acid moiety of the esters may be selected from the (+)-cis-isomer, the (+)-trans-isomer, the (i)-cis-isomer, the (+)- trans-isomer and the (+)-cis-trans-isomer; the stereochemistry refers to that of the cyclopropane ring.

The preferred isomers of formula (I) is 3-phenoxybenzyl-(+)-ds, trans-2,2 dimethyl-3-(2,2-dichlorovinyl)cyclopropane- I -carboxylate, but other isomers are not excluded, for example 3-phenoxybenzyl-(+)-trans-2,2-dimethyl-3-(2,2-dichloro- vinyl)cyclopropane- I-carboxylate.

The pesticidal activity of these esters is potentiated when used in combination with a pesticidal carbamate, especially one selected from l-naphthyl-Nmethylcarbamate (carbaryl) and 3-methyl-5-isopropyl phenyl-N-(n-butamoyl)-Nmethyl carbamate (promacyl). Other pesticidal carbamates (hereinafter defined as those carbamates which have acaricidal activity) may however be used.

The potentiating compositions of this invention are particularly effective against strains of acarines which are susceptible to conventional carbamate acaricides; against those strains which are resistant to organophosphorus and carbamate ixodicides such as the cattle tick Boophilus microplus (Can.), and against those strains which are resistant to pyrethroids. The compositions of this invention are particularly valuable in controlling acarine ectoparasites of animals, particularly those ticks of the genera Boophilus, Rhipicephalus, Amblyomma, Hyalomma, Ixodes, Haemaphysalis, Dermacentor and Anocentor, and mites of verterinary importance for example the sheep scab mite Psoroptes ovis. Such ectoparasites infest stock and domestic animals and fowls, depending upon the location of the host and the particular ectoparasite. Common hosts are cattle, pigs, sheep, goats, horses, camels, chickens, dogs and cats.

The compositions of this invention may be used for protecting the host against infestations of Ixodid and Sarcoptic pests by application of the compositions themselves or in a diluted form in known fashion,-as a dip, a spray, a dust, a paste, cream, gel, foam, shampoo or grease, a pressure-pack, an impregnated article, or a pour-on formulation. Dips are not applied per se, but the animals are immersed in a dipping bath containing the dip wash. Sprays may be applied by hand or by means of a spray race or arch or automatic treadle. Dusts may be distributed over the animals by hand application from suitable containers of incorporated in perforated bags attached to trees or rubbing bars. Pastes, foams, creams, gels, shampoos and greases may be applied manually or distributed over the surface of an inert material against which animals rub and transfer the material to their skins. Pour-on formulations are dispensed as a unit of liquid of small volume on to the backs of animals such that all or most of the liquid is retained on the amimals.

The compositions may be presented either as formulations ready for use on the animals or as formulations requiring further dilution prior to application, but both types of formulations comprise a pyrethroid as defined above in combination with at least one carbamate compound as defined above in intimate admixture with one or more carriers or diluents. The carriers may be gaseous or solid or liquid or comprise mixtures of such substances and may be selected from one or more of the following: a solvent, an inert carrier, wetting, stabilising, emulsifying, thickening, dispersing and surface active agents.

Dusts may be prepared by intimate admixture of the chosen compound with a powdered solid inert carrier for example suitable clays, kaolin, talcs, powdered chalk, calcium carbonate, Fuller's Earth, gypsum, diatomaceous earths and vegetable carriers.

Sprays of a composition of this invention may comprise a solution in an organic solvent (e.g. those listed below) or an emulsion in water (dip wash or spray wash) prepared in the field from an emulsifiable concentrate (otherwise known as a water miscible oil) or a water dispersible powder which may also be used for dipping purposes. The concentrate preferably comprises a mixture of the active ingredients, with or without an organic solvent and one or more emulsifiers.

Solvents may be selected from kerosene, ketones, alkanols, xylene, aromatic naphtha, and other solvents known in the formulating art. The concentration of emulsifiers may be varied within wide limits and are-conveniently non-ionic or a mixture of non-ionic and anionic surfactants. The non-ionic surfactants will include polyoxyalkylene ethers of alkyl phenols, or of alcohols. The anionic compounds include salts of alkylaryl sulphonic acids.

Dip washes may be prepared not only from emulsifiable concentrates but also from wettable powders comprising a composition of this invention in intimate admixture with an inert carrier and one or more surface active agents, and possibly a stabiliser and/or an antioxidant.

Greases may be prepared from vegetable oils, synthetic esters of fatty acids or wool fat together with an inert base such as soft paraffin. A composition of this invention is preferably distributed uniformly through the mixture in solution or suspension. Greases may also be made from emulsifiable concentrates by diluting them with an ointment base.

Pastes are also semi-solid preparations in which a composition of this invention may be present as an uniform dispersion in a suitable base such as soft or liquid paraffin or made on a non-greasy basis with glycerin, mucilage or a suitable soap. As greases and pastes are usually applied without further dilution they should contain the appropriate percentage of the composition required for treatment.

Aerosol sprays may be prepared as a simple solution of the active ingredients in the aerosol propellant and a co-solvent such as halogenated alkanes and the solvents referred to above, respectively. Pour-on formulations may be made as a solution emulsion or suspension of a composition of this invention in a liquid medium which is of a viscosity such as to minimize loss of the formulation by run off from the surface of the animals. The pour-on formulation may be applied by a drenching gun, syring or ladle or any other method known in the art.

A composition of the present invention preferably contains (595%) weight by weight of a pyrethroid selected from structural formula (I) and between (5-95V0) weight by weight of a carbamate compound as defined hereinabove. The concentration of active ingredients present in a formulation applied to the pests or to their environment may be in the range of (0.0001--200/,) by weight per unit volume of formulation.

The following Examples are provided by way of an illustration of the present invention and should not be construed as in any way constituting a limitation thereof.

Example 1.

Engorged female ticks of the Biarra strain of Boophilus microplus are immersed, in groups of 20 ticks per concentration, in a range of dilutions of the carbamate in combination with 3-phenoxybenzyl (+)-cis,trans-2,2-dimethyl-3-(2,2- dichlorovinyl) cyclopropane-1-carboxylate (hereinafter referred to as Permethrin) at different ratios of carbamate to Permethrin.

The composite wash is prepared immediately prior to the test by dilution (with water) of the two constituents. The constituents may be in the form of miscible oil or wettable powder formulations. The desired range of concentrations for the test is obtained by further dilution of this master solution or wash.

The ticks are removed from the wash after 10 minutes, dried, and stuck dorsalside down on double-sided adhesive tape. They remain in this position for 14 days when the numbers laying viable eggs are determined. From this data a regression line is plotted (concentration against 0/, inhibition of egg-production) and the IR90 and IR99 values determined (Table 1).

IR90 = concentration at which 90% inhibition of egg-production occurs.

IR99 = concentration at which 99% inhibition of egg-production occurs.

The values so obtained for the composite wash are compared with similar values obtained for the constituents of the composite wash when used alone. By reference to the equation for the harmonic mean, the factor of potentiation is determined (Table 2).

The equation for the harmonic mean is: Proportion of A + Proportion of B X = Proportion of A + Proportion of B IR90 A IR90 B IR90 A IR90 B x IR90 mixture of A and B Y x Proportion of A Factor of Potentiation (FOP) Proportion of A + B The FOP figures for the IR90 values were calculated in the same way.

Example 2 - Wettable Powder Formulations (a) Permethrin 25.0 parts by weight Carbaryl 5.0 parts by weight Celite Grade 209 64.5 parts by weight Bevaloid 35/2 5.0 parts by weight Dispersol BX 0.5 parts by weight 100.0 Celite (Registered Trade Mark) Grade 209 is a fine, purified grade of diatomaceous earth supplied by Johns Manville.

Bevaloid (Registered Trade Mark) 35/2 is a dispersing agent and is a condensation of formaldehyde and sodium naphthalene sulphonate. It is supplied by Bevaloid Limited.

Dispersol (Registered Trade Mark) BX is a wetting agent and is sodium alkyl naphthalene sulphonate. It is supplied by ICI Limited.

(b) Permethrin 10.0 parts by weight Promacyl 10.0 parts by weight Celite Grade 209 74.5 parts by weight Bevaloid 35/2 5.0 parts by weight Dispersol BX 0.5 parts by weight 100.0 Celite Grade 209 is a fine, purified grade of diatomaceous earth supplied by Johns Manville.

Bevaloid 35/2 is a dispersing agent and is a condensation product of formaldehyde and sodium naphthalene sulphonate. It is supplied by Bevaloid Limited.

Dispersol BX is a wetting agent and is sodium alkyl naphthalene sulphonate. It is supplied by ICI Limited.

Example 3 - Miscible Oil Formulation Permethrin 5.0 parts by weight Promacyl 5.0 parts by weight Esso Solvent 200 70.0 parts by weight Ethylan KEO 20.0 parts by weight 100.0 Ethylan (Registered Trade Mark) KEO is an emulsifying agent which is nonyl phenol ethoxylate supplied by Lankro Chemicals Limited.

Esso Solvent 200 is a mobile oil which consists of 95% of aromatic hydrocarbons.

Example 4.

Following the same procedure as in Example 1, IR90 and IR99 values were obtained for permethrin and promacyl alone against B. microplus (Biarra strain).

An equitoxic mixture of permethrin and promacyl was then prepared and the IR90 and 1R99 values for the equitoxic mixture were evaluated as before.

The factors of potentiation were then determined as the ratio of the expected value over the actual value. (Table 3).

Example 5 - Wettable Powders Parts by weight Permethrin 20.0 12.5 5.0 Carbaryl 4.0 12.5 25.0 Diatomaceous Earth 71.0 70.0 65.0 Sodium alkyl naphthalene sulphonate 1.0 1.0 1.0 Bevaloid 35/2 4.0 4.0 4.0 100.0 100.0 100.0 Bevaloid 35/2 is a dispersing agent which is defined in Example 2.

Example 6 - Dusting Powders Parts by weight Permethrin 1.7 1.0 0.3 Carbaryl 0.3 1.0 1.7 Talc 98.0 98.0 98.0 100.0 100.0 100.0 TABLE 1 IR90/99 Values for the Carbamates alone and Compositions of these with Permethrin at Various Ratios

PERMETHRIN IXODICIDE COMPOSITE ALONE RATIO 1:1 RATIO 1:5 RATIO 5:1 WITH IR90 IR99 IR90 IR99 IR90 IR99 IR90 IR99 Carbaryl > 1.0 0.027 0.050 0.0090 0.016 0.074 0.11 Promacyl 0.34 > 1.0 0.032 0.054 Key:- Ratio Carbamate/Permethrin TABLE 2 Factors of Potentiation of Composites of certain Carbamates and Permethrin

PERMETHRIN COMPOSITE RATIO 1:1 RATIO 1:5 RATIO 5:1 WITH IR90 IR99 IR90 IR99 IR90 IR99 Carbaryl > 2.3 > 1.4 > 3.4 Promacyl 1.7 Key:- Ratio Carbamate/Permethrin TABLE 3 The activity of an equitoxic mixture of promacyl and permethrin against viable oviposition of engorged female ticks of the Biarra strain of B. microplus

EQUITOXIC MIXTURE Expected value Expected Actual Actual value ALONE Value Value IR90 IR99 IR90 IR99 IR90 IR99 IR90 IR99 Promacyl 0.34 > 1.0 0.20 > 0.57 0.074 0.14 2.7 > 4.1 Permethrin 0.066 0.13 Expected value = Factor of Potentiation Actual value

IR90 # = Same meaning as in Table 1 IR99

Claims (7)

WHAT WE CLAIM IS:

1. A method for controlling veterinary ectoparasites of the sub-Orders Ixodidae and Sarcoptiformes of mammals and birds which comprises the application of a parasiticidally effective amount of a pyrethroid of formula

in combination with at least one pesticidal carbamate (as hereinafter defined) to the ectoparasite or to its environment.

2. A method according to claim I wherein the pyrethroid is 3-phenoxybenzyl (+)-cisstrans-2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane- 1 -carboxylate.

3. A method according to claim 1 or 2 wherein the carbamate is carbaryl or promacyl.

4. A method according to any of claims 1 to 3 wherein the ectoparasite is of the family Ixodidae.

5. A method according to any of claims 1 to 4 wherein a mixture of a pyrethroid as defined in claim 1 in combination with at least one pesticidal carbamate formulated as an emulsion in water is applied.

6. A method according to any of claims 1 to 4 wherein a formulation comprising said composition in intimate admixture with a carrier or diluent in the form of a dusting powder, aqueous suspension, solution or pressure-packed formulation is applied.

7. A method according to claim 5 or 6 wherein the said formulation comprises from 0.0001% to 20% by weight of active ingredients per unit volume of formulation.