GB2187644A - Insecticidal compositions - Google Patents

Description

SPECIFICATION Insecticidal compositions The invention relates to aspects of insect and virus control in plants and to certain compositions for use in this field.

UK Patent No. 1,181,657 describes interalia the compound 2-dimethylamino-5,6-dimethylpyrimidin-4-yl dimethyl carbamate (hereinafter referred to as Compound A), together with processes for its preparation and its use as an insecticide.

Published European Patent No. 0017738 discloses insecticidal and miticidal compositions containing Compound A, at least one organic phosphorus compound, methyl carbamate compound or pyrethroid and an inert carrier. These compositions are said to be particularly effective against leafhoppers.

The applicants have found that by applying Compound A in combination with a pyrethroid type insecticide, suprisingly beneficial results are obtained in relation to the control of aphids and viruses transmitted by aphids.

According to the present invention, there is provided a method of preventing aphid-transmitted virus infections in plants, which method comprises applying to the plant 2-dimethylamino-5,6-dimethyl pyrimidin4-yl dimethyl carbamate and a pyrethroid.

Suitable pyrethroidsfor use in the method include cyhalothrin, permethrin, cypermethrin,fenvalerate, fluorocythrin, deltamethrin, alfoxylate, phenothrin, cyphenothrin, fenpropathrin, cyfluthrin, tralomethrin, tralocythrin, esfenvalerate, fluvalinate, furamethrin, fenfluthrin, fenpyrithrin, phencyclate, tetrallethrin, pyrethrin, cinerin, jasmolin, allethrin, barthrin, dimethrin, bioallethrin, alphamethrin,tetramethrin, resmethrin, bioresmethrin, flumethrin, empenthrin, and (RS)-cyano-(6-phenoxy-2-pyridyl)methyl (IRS)-trans 3-(4-tert-butylphenyl )-2,2-dimethylcyclopropanecarboxylate.

All types of aphid-transmitted viruses including persistent, semi-persistent and non-persistent can be controlled using this method. This is particularly important in crops such as potato and sugar beet where mixtures of virus types occur. Examples of such viruses include beetyellows, potato leaf roll and potato severe mosaic virus (PVY).

The compounds used in the method demonstrate good persistence and thereby control the secondary spread of virus as well as preventing new infections.

The method of the invention may be employed as part of a strategy for overcoming insect resistance to pyrethroids.

The combination of compounds employed in the method have a persistent effect combined with rapid knockdown against aphids. Thus in a further aspect the invention provides a method of controlling oreliminating aphids which method comprises administering to the aphid ortho the environment thereof an insecticidally effective amount of 2-dimethylamino-5,6-dimethyl pyrimidin-4-yl dimethyl carbamate and a pyrethroid.

Suitable pyrethroids for use in this method are those listed above.

This method is particularly useful in agricultural applications to control aphids in crops. All major species of aphid including green and blackaphidscan be controlled bythismethod.Arapid knockdown effect (demo nstrated by the inhibition of feeding) whateverthe weatherconditions and no subsequent recovery ofthe treated aphid population is apparent using this method.

The combination of compounds employed exhibit several types of aphicidal activity ie, contact,translaminar, fumigant, systemic and repellent or anti-feeding and so serveto control aphids in all parts ofthe crop canopy.

Preferably the combination of compounds used in the above described method are applied in the form of a single composition comprising a pyrethroid, Compound Aand a carrierordiluent.

Certain of the compositions employed in the above described methods are novel and these form part ofthe invention.

Therefore in a further aspect, the invention provides an insecticidal composition comprising 2 dimethylamino-5,6-dimethyl pyrimidin-4-yl dimethyl carbamate, a pyrethroid selected from cyhalothrin, de ltamethrin, fluorocythrin, alfoxylate, phenothrin, cyphenothrin, fenpropathrin, cyfluthrin, tralomethrin, tralocythrin, esfenvalerate, fluvalinate, furamethrin, fenfluthrin,fenpyrithrin, phencyclate, tetrallethrin, pyrethrin, cinerin, jasmolin, barthrin, dimethrin, bioallethrin, alphamethrin, tetramethrin, resmethrin, bioresmethrin, flumethrin, empenthrin, and cyano-(6-phenoxy-2-pyridyl)methyl 2,2-dimethyl-3-(p-tbutylphenyl)cyclopropane carboxylate; and a carrier or diluent.

The applicants have found that by combining Compound Awith a pyrethroid an unexpectedly high level of insecticidal activity is observed.

Preferred pyrethroids include cyhalothrin and deltamethrin. A particularly preferred pyrethroid for use in the composition and methods of the invention is cyhalothrin which is referred to hereinafter as Compound B.

This pyrethroid, whose chemical name is -cyano-3-phenoxybenzyl-cis-3-(Z-2-chloro-3,3,3-trifluoro-1 - propenyl)-3,3,3-trifluoro-1 -propenyl)-2,2-dimethylcyclopropane carboxylate, is described in UK Patent No 1601344 (corresponding to US patent No 4, 183,948) together with its preparation.

Compound B exists in a numberof isomericforms as described in US Patent No 4,510,160 and 4,510,098.

All isomericforms can be employed in the present invention. However preferably a racemic mixture ofthe enantiomers represented by (S)-a-cya no-3-phenoxybenzyl (1 R), cis-3-(Z-2-chloro-3,3,3-trifluoro-1-propenyl)- 2,2-dimethylcyclopropanecarboxylate and (R)-a-cyano-3-phenoxybenzyl (1 S)-cis-3-(Z-2-chloro-3,3,3trifluoro-1 -propenyl)-2,2-dimethylcyclopropanecarboxylate is employed.

The compositions ofthe invention are active against a wide range of insect pests. Thus in a furtheraspect the invention provides a method of controlling or eliminating insect pests, which method comprises admini stering to the insect orto the environment thereof an insecticidally effective amount of a composition as described above.

The compositions may be in the form ofdusting powders or granules wherein the active ingredients are mixed with a solid diluent or carrier. Suitable solid diluents or carriers may be,forexample, kaolin, bentonite, kieselguhr, dolomite, calcium carbonate, talc, provided magnesia, Fuller's earth, gypsum, Hewitt's earth, diatomaceous earth and China clay. Compositions for dressing seed, for example, may comprise an agent assisting the adhesion of the composition to the seed, for example, a mineral oil.

The compositions may also be in the form of dispersible powders or grains comprising, in addition to the active ingredients, a wetting agentto facilitatethe dispersion of the powder or grains in liquids. Such pow ders or grains may include fillers, and suspending agents.

The compositions may also be in the form of iiquid preparation to be used as sprays which are generally aqueous dispersions or emulsions containing the active ingredients in the presence of one or morewetting agents, dispersing agents, emulsifying agents or suspending agents.

Wetting agents, dispersing agents and emulsifying agents may be ofthe cationic, anionic or non-ionic type. Suitable agents of the actionictype include, for example, quaternary ammonium compounds, forex- ample, cetyltrimethyl- ammonium bromide. Suitable agents ofthe anionictype include, for example, soaps, salts of aliphatic monoesters of sulphuric acid, for example sodium lauryl sulphate, salts ofsulphonated aromatic compounds, for example sodium dodecyl-benzenesulphonate, sodium, calcium or ammonium lignosulphonate, butyl-naphthalene sulphonate, and a mixture ofthe sodium salts of diisopropyl- and tri- isopropyl- naphthalene sulphonic acids.

Suitable agents ofthe non-ionictype include, for example, the condensation products of ethylene oxide with fatty alcohols such as oleyl alcohol or cetyl alcohol, or with alkyl phenols such as octylphenol, nonylphenol and octylcresol. Other non-ionic agents are the partial esters derived from long chain fatty acids and hexitol anhydrides, and condensation products of the said partial esters with ethylene oxide, and the lecithins.

Suitable suspending agents are, for example, hydrophilic colloids, for example polyvinyl pyrrolidone and sodium carboxymethylcellulose, and the vegetable gums, for example gum acacia and gum tragacanth.

The aqueous dispersion of emulsions may be prepared by dissolving the active ingredients or ingredients in an organic solvent which may contain one or more wetting, dispersing or emulsifying agents and then adding the mixture so obtained to water which may likewise contain one or more wetting, dispersing or emulsifying agents. Suitable organic solvents are toluene, methyl naphthaienes, xylenes, higher alkyl ben zenes for example having up to 10 carbon atoms in the alkyl chain(s), trichloroethylene, cyclohexane and isophorone.

The compositions to be used as sprays may also be in the form of aerosols wherein the formulation is held in a container under pressure in the presence of a propellant such as fluorotrichloromethane ordichlorod ifluoromethane.

Bythe inclusion of suitable additives, for example for improving the distribution, adhesive power and resistance to rain or treated surfaces, the different compositions can be better adapted forthe various uses forwhichtheyare intended.

The compositions which are to be used in the form of aqueous dispersion or emulsions are generally supplied in the form of concentrates containing a high proportion of the active ingredients, the said con- centratesto be diluted with water before use. These concentrates are often required to withstand storage for prolonged periods and aftersuch storage, to be capable of dilution with water in orderto form aqueous preparations which remain homogeneous for a sufficienttime to enable them to be applied by conventional spray equipment.The concentrates may conveniently contain from 10-85% by weight ofthe active ingredient or ingredients and generally from 25-60% by weight of the active ingredient or ingredients depending upon the purpose for which they areto be used, but an aqueous preparation container between 0.001% and 1.0% by weight of active ingredient or ingredients may be used.

The ratio of Compound A: pyrethroid employed in the composition is suitably in the range offrom 50:1 to 4:1 preferably from 25:1 to 5:1. The rate of which the compositions are applied will depend upon numerous factors including the particular pyrethroid employed,the type of crop treated, the degree of infestation and soon. However in general they will be applied such that the Compound A is present at from 50-250 g/ha and the pyrethroid will be present at from 5-20 g/ha.

The following Examples illustrate the invention.

Example 1 Aseries of compositions were prepared as follows: (a) Wettablepowder Percentage wlw Compound 15 Compound B 5 Lignosulphonate dispersant (Vanispeste CB) 5 An ionic wetting agent (Empicol hZ) 3 Aromatic solvent(Shellsol E) 5 Silica 10 Kaolin to 100 (b) Water dispersible grain Compound A 40 Compound B 2 Kaolin 10 Lignosulphonate binder('Polyfon' H) 5 An ironic wetter agent ('Aerosol' OTB) 2.5 Anhydroussodium acetate 10 'Crex' to 100 (c) Emulsifiable concrete Compound A 10 Compound B 0.5 Anionic/Nonionic Emulsifier Blend ('Aerox'3404F/3412F) 10 Isophorone 10 Xylene to 100 Example2 Leaves infected with BYV were sprayed to 'run-off' with commercial formulations diiuted with water, as follows: 1. deltamethrin @ 0.002% active ingredient 2. pirimicarb@ 0.03%a.i 3. heptenophos @ 0.03% a.i 4. pirimicarb (0.03% a.i) + deltamethrin (0.002% a.i) 5. heptenophos (0.03% a.i) + deltamethrin (0.002% a.i) Control leaves were left untreated. Sprayed leaves were allowed to dry. Four groups of nine peach-potato aphids (Myzuspersicae), highly resistant to insecticides (R2), were caged for 24 hours onto these leaves. At the end of this period all aphids, including apparently dead ones, were transferred in groups ofthreeto untreated sugar beet seedlings. On the following day the aphids were killed with pirimicarb.The number of sugar beet plants infected with BYVwas measured later. The whole experiment was repeated on five occassions.

The results are shown in Table I.

Tablel Treatment Total number of sugar beet seedlings infected with BYV (Out of 60) Control 35 Deltamethrin 17 Pirimicarb 6 Heptenophos 31 Deltamethrin + Pirimicarb 0 Deltamethrin + Heptenophos 18 Example 3 Plots (6 rows x 8m) containing sugar beet (variety-Regina) atthe4-leaf stage of growth were sprayed with various commercial formulations of pirimicarb, cyhalothrin and a mixture of the two. Each treatmentwas applied to 3 plots. The number of each species of aphids (Aphis fabae and Myzuspersicae) on each plantwas countedafter2,7and 14days.

The results are shown in Table 2.

Table2 Pre-treatmentaphid numbers: 1 02Aphis fabae and 58.5 Myzuspersicae.

Treatment Rate applied in g Total No aphids per plant active ingredient/ha Aphisfabae Myzusperiscae Days after spraying 2 7 14 2 7 14 Untreated - 152 245 693 67 90 192 Pirimicarb 140 10 91 356 4 22 44 Primicarb + 100+ 8 90 384 4 7 25 Cyhalothrin 5 Cyhalothin 5 43 127 357 19 13 30 The mixture showed both rapid kill of Myzus persicae as well as good persistence as compared with the individual components. This species is the one primarily responsiblefortransmitting plantvirus.

The effect onAphis fabaewas less marked although the initial effect and persistancewas comparable to that ofthe higher dose of pirimicarb and better than the cyhalothrin alone.

Claims (9)

1. A method of preventing aphid-transmitted virus infections in plants, which method comprises applying to the plant 2-dimethylamino-5,6-dimethyl pyrimidin-4-yl dimethyl carbamate and a pyrethroid.

2. A method of controlling or eliminating aphids which method comprises administering to the aphid or to the environmentthereofan insecticidally effective amount of 2-dimethylamino-5,6-dimethyl pyridimidin4-yl dimethyl carbamate and a pyrethroid.

3. A method according to claim 1 or claim 2 wherein the pyrethroid is selected from cyhalothrin, per- methrin, cypermethrin, fenvalerate, fluorocythrin, deltamethrin, alfoxylate, phenothrin, cyphenothrin, fenpropathrin, cyfluthrin, tralomethrin, tralocythrin, esfenvalerate, fluvalinate, furamethrin, fenfluthrin, fen- pyrithrin, phencyclate, tetrallethrin, pyrethrin, cinerin, jasmolin, allethrin, barthrin, dimethrin, bioallethrin, alphamethrin, tetramethrin, resmethrin, bioresmethrin,flumethrin, empenthrin, and (RS)-cyano-(6phenoxy-2-pyridyl )methyl (I RS)-trans-3-{4-tert-butyl phenyl )-2,2-dimethylcyclopropanecarboxylate.

4. A method according to claim 3 wherein the pyrethroid is cyhalothrin or deltamethrin.

5. A method according to any one of claims 1 to 4wherein the 2-dimethylamino-5,6-dimethyl pyrimidin4-yl dimethyl carbamate and the pyrethroid are applied in a single composition.

6. An insecticidal composition comprising 2-dimethylamino-5,6-dimethyl pyrimidin-4-yl dimethyl carbamate, a pyrethroid selected from cyhalothrin, deltamethrin, fluorocythrin, alfoxylate, phenothrin, cyphenothrin, fenpropathrin, cyfluthrin, tralomethrin, tralocythrin, esfenvalerate, fluvalinate, furamethrin,fen- fluthrin, fenpyrithrin, phencyclate, tetrallethrin, pyrethrin, cinerin, jasmolin, barthrin, dimethrin, bioallethrin, alphamethrin, tetramethrin, resmethrin, bioresmethrin, flumethrin, empenthrin, and (RS)-cyano-(6phenoxy-2-pyridyl )methyl (lRS)-trans-3-(4-tert-butylphenyl)-2,2-dimethylcyclopropanecarboxylate.

7. A insecticidal composition comprising 2-dimethylamino-5,6-dimethylpyridimidin-4-yl dimethyl carbamate, a-cyano-3-phenoxybenzyl-cis-3-(Z-2-chloro,3,3,3-trifluoro-1 -propenyl )-2,2 dimethylcyciopropanecarboxylate and a carrier or diluent.

8. A composition according to claim 7 wherein the carboxylate compound is in the form of a racemic mixture of the enantiomers represented by (S) -ol-cya no-3-phenoxybenzyl (I R)-cis-3-(Z-2-chloro-3,3,3trifluoroprop-1 -enyl)-2,2-dimethylcyclopropanecarboxylate and (R)-a-cyano-3-phenoxybenzyl (IS)-cis-3-(Z 2-chloro-3,3,3-trifiuoroprop-1 -enyl)-2,2-dimethylcyclopropanecarboxylate.

9. A method of controlling or eliminating insect pests which method comprises administering to the insectorto the environment thereof an insecticidally effective amount of a composition according to any one of claims 6to 8.