CA2098389A1 - Control of insects - Google Patents

Abstract

A method of controlling insects on plants which comprises the application to the plant of an effective amount of an aqueous formulation that contains a pyrethroid insecticide as active ingredient, an evaporation retardant and an emulsifier, optionally together with a carrier or solvent for the active ingredient, which the formulation satisfies the formula: mass of oil phase/mass of retardant Í Moil/Mretardant . X Exp[[ln(L/4)+[C x ln(AXB)]]/C]
where L is less than or equal to 15, A = 700376, B = -1.51, C =
0.8472, Moil is the weighted average relative molar mass of the oil phase, Mretardant is the average molar mass of the retardant, and X = Moil1.8 / Y where Y is the molar solubility ratio of the formulation, defined as the minimum number of moles of oil phase which will dissolve the retardant, divided by the number of moles of retardant, provided that, in the formula above, any solvent which has no liquid phase at 27 ·C at atmospheric pressure is excluded.

Description

W093/077~0 ~ PCT/EP92/02~5 CONTROL OF INSECTS

The present invention rslates to a method of controlling the 5 damage caused by phytophagus insects to crops by the application of an anti-evaporant formulation containing an insecticide.

European Patent Specification 331474 discloses spray 10 formulations which have evaporation retardant properties such formulations contain an oil phase, a retardant and an active ingredient, for example a pesticide.

Mite resurgance is a phenomenon encountered when broad 15 spectrum insecticides, such as the pyrethroids, are used to control insects on crops. Treatment with the pyrethroids controls the major pest on the crops, for example caterpillars, bllt results in an explosion of the mite population which was previously at a low density (mite 20 resurgance). One reason for mite resurgance is that the pyrethroids stimulate the ~ites to increase their reproductive rate.

It has now been found that formulations of European Patent 25 Specification 331474 containing a pyrethroid can be applied to crops without causing mite resurgance.

Accordingly, the present invention provides a method of controlling insects on plants which comprises the application 30 to the plant of an effective amount of an aqueous formula~ion that contains a p~rethroid insecticide as active inyredient, an evaporation retardant and an emulsifier that satisfies the formula:

35 mass of oil phase <
mass of retardant 1 `l - - ' ,.. , . , ~ ... ... . ....... .. ... .. ..... ........ . .

2 0 ~
WO93tO77~Q PCT/EP92/02~5 Moil - - . X Exp[[ln(L/4)+[C x ln(AXB)]]/C]
~ etardant 5 where L is less than or equal to 15, A = 700376, B = -1.51, C = 0.8472, :
Moil is the weighted average :relative molar mass o~ the oil phase Mretardant is the average molar mass of the retardant, and ~ = Mo~ 8 / Y

where Y is the molar solubility ratio of the formulation, :
defined as the minimum number of moles of oil phase which - 15 will dissolve the retardant, divided by the number of moles of retardant, provided that, in the Formula above, any solvent which has no liquid phase at 27C at atmospheric pressure is excluded. .

20 The "oil phase" is the liquid non aqueous phase and will comprise one or more of the active ingredient, the solvent -therefore and in some cases the emulsifier.

For the avoidance of doubt, and to clarify any ambiguities 25 which may arise in the printing or copying of this specification, it is to be noted that the relational symbol "<" in the Formula is "less than or equal to", "Exp" means the exponential of what follows in brackets, "ln" means the natural logarithm, i.e. loge, L is divided by 4, X is raised 30 to the power B, B is a negative value tminus 1.51) and, in the definition of X, Moil is raised to the power 1.8.

Preferably I, is less than 12, 10, or 8 and is most preferably less than 5. A distilled water spray has an "L" value of 35 about 26, and most conventional diluted formulations have a value o~ about 22-30. In the formulatio~s of the invention, "L" can be set at a desired value in order to calculate the required ratios of the ingredients.
.

u ~
93/07750 PCT/EP92/02~5 Moil, the average molecular weight of the oil phase, is the weighted average, i.e. taking into account the relative proportions of the ingredients.

5 The value "Y", namely the molar solubility ratio of the formulation, may be derived empirically by making up at 40C
a series of mixtures with different ratios of oil phase to alkanol, allowing the mixtures to cool to 27C, leaving the cool mixtures for at least 48 hours at 27C, and determining 10 the amount, in moles, of the oil phase which is needed to dissolve completely a given amount of retardant, in moles.
The former is then divided by the latter to give Y.

Examples of pyrethroid insecticides include those of the 15 formula (I) ~//~0 0~

where R is \/ , ~ C = CH
Z

or Rl ~ (NH)n - CH

Rl is halo, CF3 or CHF20, R2 is hydrogen or halo, n is 0 or 1, -:
and Z and Zl are each independently selected from halo, CF3 10 and methyl, or Z(Zl)c= represents :
x ,c . .
o=C CF3 O--C~ , X is hydrogen or halo, and X is H, CN or C--~H, or pyrethroids o~ formula :
Cl Cl I

\CX~O~/
ETO CN

or ~ ~ c~ \c Examples of pyrethroids are :
35 3-phenoxybenzyl-(lRS)-cis,trans-3-(2,2-dichlorovinyl-2,2-dimethylcyclopropanecarboxylate (permethrin), (RS)-~-cyano-3-phenoxybenzyl-(lRS)-cis,trans-3-~2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate ; .... . ., . -. -; . .. . - . - - -f~ v v ~J u ~ v W093/07750 PCT/EP92/02~5 (cypermethrin) and its individual isomers such as the (lRS) cis isomer (alphamethrin) and the four isomer mixture betamethrin, (S)-~-cyano-3-phenoxybenzyl-(lR)-cis-3-(2,2-dibromovinyl)-2,2-5 dimethylcyclopropanecarboXylate (deltamethrin), or a reaction - . mixture comprising two enantiomeric pairs in approximately ratio 2:3, (S)-~-cyano-3-phenoxybenzyl-(lR)-cis-3-(2,2-dichloro-vinyl)-2,2-dimethylcyclopropanecarboxylate, lO (R)-~ cyano-3-phenoxybenzyl-(lS)-cis-3-(2,2-dichloro-vinyl)-2,2-dimethylcyclopropanecarboxylate with (S)-~-cyano-3-phenoxybenzyl-(lR)-trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate (R)-~ cyano-3-phenoxybenzyl-(lS)-trans-3-(2,2-dichlorovinyl)--15 2,2-dimethylcyclopropanecarboxylate (beta-cypermethxin), (RS)-~-cyano-3-phenoxybenzyl-(Z)-(lRS)-cis-3-(2-chloro-3,3,i-trifluoropropenyl)-2,2-dimethylcyclopropanecarboxylate (cyhalothrin) and a mixture of its (S)(Z)-(lR)-cis and (R)(Z)-(lS)-cis-isomers, 20 (s)-~-cyano-3-phenoxybenzyl-(lR,3S)-3-[(Z)-3-[bis(trifluoro-methyl)methoxy]-3-oxo-l-propenyl~-2,2-dimethylcyclopropane-carboxylate (acrinathrin), (RS)-~-cyano-3~phenoxybenzvl-(~S)-2-(4-chlorophenyl)-3-~ethylbu~yrate (fenvalerate) and the single (S),(S) isome-25 (esfenvalerate),(RS)-~-cyano-3-phenoxybenzyl-(S)-2-(4-difluoromethoxy-phenyl)-3-methyl butyrate (flucythinate), (RS)-~-cyano-3-phenoxybenzyl-N-(2-chloro~ rifluorc-p-tolyl)-D-valinate (fluvalinate), 30 (Rs)-~-cyano-4-fluoro-3-phenoxybenzyl-(lRs)-cis-trans-3-(2 dichlorovinyl)-2,2-di-methylcyclopropanecarboxylate (cyfluthrin), (RS)-~-cyano-4 -f luoro-3-phenoxybenzyl-(lRS)-cis-trans-3-(^-chloro-2(4-c~lorophenyl)vinyl)-2~2-dimethylcyclopropane 35 carboxylate (flumethrin), 2-methylbipnenyl-3-yl-methyl-(~) (lRs~3Rs)-3-(2-chloro-3~3~3 -t~if luoro-prop-1-enyl)-2,2-dimethylcyclopropanecarboXylate (Bifenthrin);
the allethrins, for example (lRS)-3-allyl-2-methyl 4-.

.

, -f W093/07750 8 9 pcT/En2/o234~

oxocylopent-2-enyl-(lR,3R)-2,2-dimethyl-3-(2-methylprop-1 enyl)-cyclopropanecarboxylate (bioallethrin), (lS)-allyl-2-methyl-4-oxocyclopent-2-enyl-(lR,3R)-2,2-dimethyl~3-~2-methylprop-1-enyl)cyclopropanecarboxylate (S-5 bioallethrin), and mixtures of allethrin isomers (esbiothrin);the resmethrins, for example 5--benzyl-~-furylmethyl(IRS, 3RS;
IRS, 3SR)-2,2-dimethyl-3-(2-methyl-prop-1-enyl)cyclopropane-carboxylate (resmethrin) and 5--benzyl-3-furylmethyl (lR,3R)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate 10 (bioresmethrin).
Octadecan-1-ol and, particularly, hexadecan-1-ol are preferred evaporation retardants. Hexadecan-1-ol (also known as cetyl alcohol) is usually available commercially as a mixture with a minor proportion of octadscan-1-ol (stearyl alcohol~ and 15 such "cetostearyl alcohol" is quite satisfactory.
Heptadecan-l-ol performs adequately but is much more expensive. Other highly effective evaporation retardants include 1-hexadecylamine, 1-heptadecylamine and 1-octadecylamine. Less preferred evaporation retardants include 20 hexadecan-2-ol, 1,2-hexadecandiol, methyl stearate, stearyl acetate, methyl palmitate and 1,2-octadecandiol. N-alkoxy-alkanols may be used, for example CH3(CH2)210C2~40H, H3(C~2)21C3H6H~ CH3(CH2)170C2H4OH or CH3(C~2)150C2~40H, as may oxyethylene-docosanol and mixtures of any of the said 25 evaporation retardants.

The amount of emulsifier present in the formulation will be less than twice the amount of the evaporation retardent present and will preferably be less than the amount of the 30 evaporation retardant present.

The emulsifier may be any suitable compound or mixture of compounds. Cationic emulsifiers can be used, but they tend to irritate the user's eyes. Anionic emulsi~iers such as 35 calcium dodecyl benzenesulphate (CDBS) or sodium d-isopropyl naphthalenesulphonate (SDNS) can also be use~, but these are not as effective at stabilising the emulsion whilst maintaining evaporation retarding properties. Preferably, the .: : ~ . : . .

W093/07750 2 0 9 8 3 8 9 PCT/EP92/02~

emulsifier is a non-ionic compound, or mixtur~ o~ non-ionic compounds, having an HLB (hydrophilic/lipophilic balance) of 6-20 and pre~erably 8-18. Suitable compounds include polyoxyethylPne stearyl ethers (PSE), polyoxyethylene 5 monolaurates (PEM), polyoxyethylene mono-oleates (P~O), sorbitan mono-oleate (SMO), nonylphenol ethoxylate (NPE), polyethylene glycol (PEG) and blends of oleyl ethoxylate (10 mole), and PEG20 glyceryl oleate (OE/PGO).

10 These emulsifiers are available as follows:

Abbrev. Trade name Supplier OE/PGO Tegoplant Th.
EMll Goldschmidt Ltd.
PSE Brij 72, Brij 76, ICI Speciality Brij 78 Chemicals PEM Tween 20 ICI Speciality : .
Chemicals 20 SMO Span 80 ICI Speciality : :
Chemicals PMO Tween Bo ICI Speciality Chemicals NPE Ethylan Lankro :
KEO,55,BV Chemicals ~ .:
Limited CDBS Arylan CA Lankro Chemicals Limited 30 SDN Aerosol OS Cyanamid GB ~.
Ltd.

- The solvent, at least for an oil-soluble active ingredient, preferably has a low relati~e molecular mass, namely less 35 than about 200.
Suita~le compounds include aromatic hydrocarbons, lower alXyl esters, lower ketones, lower alkanols and lower alXanes, the term "lower" meaning C1~12, preferably C1-10 and more W093/07750 2 O 9 8 ~ 8 9 PCT/EP92/02~5 preferably Cl-8 .

Particular solvents include the following, all available from Exxon Chemicals Limited;
"Solvesso 150" - An aromatic hydrocarbon solvent (C9 to C11) with a distillation range 190 to 210C.

"Solvesso 200" - An aromatic hydrocarbon sol~ent (C10 to C12) lO with a distillation range 226 to 290C.
"Exxate 700" - Heptyl acetate 99% pure, or Odourless kerosene - A mixture of high boiling non-aromatic hydrocarbons consisting of paraffins and naphthenes with a distillation range of 180 to 270C.
The formulation may comprise more than one pyrethroid (optionally with a synergist or potentiator, which is regarded as an active ingredient for the purpose of the :
Formula above), more than one solvent, more than one 20 emulsifier and/or more than one stabiliser, together with other ingredients such as perfumes and dyes.

The present invention also provides a method for preventing the resurgance of mite infestation in plants when txeated with 25 pyrethroid insecticides which comprises the application to the plant of an aqueous formulatio~ that contai~s the .
pyrethroid insecticide as active ingredient, an evaporation retardant and an emulsifier that satisfies the Formula described hereinbefore.
The following examples illustrate representative formulations to be applied and the biological properties of such formulations:

35 Example 1 ~Eormulation 1) Ingredient % w/w Permethrin (Technical) . 10.32 r .

" ., , ':
,:

~,,r~WO 93~077~0PCT/EPs2/02345 Piperonyl Butoxide (Technical~12.83 Cetyl Alcohol 3.00 Odourl2ss Xerosene 9~70 Emulsifier Blend 1.00 5 Deionised Water 62.75 Silcolapse 5000 0~10 Formaldehyde Solution 0.30 100 . 00 10 1~ Emulsifier Blend consists of 0.75% Emulgator BT02, 0.1%
BRIJ 78, 0.1% BRIJ 72 and 0.05~ TWEEN20.

Emulgator BT02 is equivalent to Tegoplant EMll described in European Patent 331474.
Biological Properties 1501m Diameter droplets o~ Ambush~ (which is a formulation marketed by ICI Americas Inc) and formulation 1 were applied 20 to 2cm diameter leaf discs cut from "Henderson" lima beans.
Both formulations were mixed in water at a rate of 12.5g a.i.
per liter.

Droplets were applied at densities of 25, 50, 75, 100, 150 and 2S 200 per leaf disc. Five replicate leaf discs were used per droplet density. Five replicate control leaf discs were left untreated.

Leaf discs were left to dry for one hour. Five adult female 30 two-spotted spider mites tTSSM) were then placed on each leaft disc using a fine camel-hair brush. ~he mites were obtained from cultures reared on greenhouse lima beans at the OARDC.
~ The leaf discs were placed on moistened cotton in 3cm diameter petri dishes and were maintained in the laboratory 35 at room temperature t22-25C).

At 24 and 48 hours following treatment, the following were assessed: mortality, the number of mites on and off the leaf ,. ... : .. .: ., , , . . : . ... -,: . . . ., .: ~

~
disc, the numbPr of eggs and the number of feeding scars.
Mites were recorded as dead when they would no~ respond to gentle prodding.

5 For each parameter measured the data were analysed using a one-way analysis of variance. Significant treatment effects were partitioned using a Student-Newman-Keuls (SNK) multiple range test. Prior to analyses, the data were first transformed using either percentages and arcsin-squareroot 10 ~mortality, irritancy) or loglO n+l (eggs/mite, scars/mite).
The effects of droplet density upon the parameters measured were then subsequently analysed using linear regression analyses.

lS The individual treatment means and the results of the SNK
multiple range test were plotted for irritancy, fecundity and feeding rate at 24 hours after exposure.
Significant treatment effects were detected in the measurements of irritancy, fecundity and feeding rate but not 20 in the measurement of mortality. In all, very few mites died throughout the study, in any of the treatments. This was ex-pected as the rates of permethrin that were chosen were selected in order to investigate the sub-lethal effects of these pesticides upon TSSM.
For all the parameters measured, no treatment effects were detected for formulation 1. However, significant treatment effects were detected with Ambush.

30 By increa~ing the droplet density, it was observed with Ambush, a significant increase in the number of TSSM leaving the leaf, which took place concomitant with a significant decrease in the number of eggs laid and the amount of feeding activity (despite a correction for the number of TSS~ that 35 remained on the leaf).

" . ` . ' ~ '`

Claims (10)

1.- A method of controlling insects on plants which comprises the application to the plant of an effective amount of an aqueous formulation that contains a pyrethroid insecticide as active ingredient, an evaporation retardant and an emulsifier, optionally together with a carrier or solvent for the active ingredient, which the formulation satisfies the formula:

?

. X Exp[[ln(L/4)+[C x ln(AXB)]]/C]

where L is less than or equal to 15, A = 700376, B = -1.51, C = 0.8472, Moil is the weighted average relative molar mass of the oil phase Mretardant is the average molar mass of the retardant, and X = Moil1.8 / Y

where Y is the molar solubility ratio of the formulation, defined as the minimum number of moles of oil phase which will dissolve the retardant, divided by the number of moles of retardant, provided that, in the Formula above, any solvent which has no liquid phase at 27°C at atmospheric pressure is excluded.

2.- A method for preventing the resurgence of mite infestation in a plant when treated with pyrethroid insecticides which comprises the application to the plant of an effective amount of a formulation as defined in claim 1.

3.- A method as claimed in claim 1 or claim 2 in which the formulation optionally comprises more than one pyrethroid (optionally with a synergist or potentiator, which is regarded as an active ingredient for the purpose of the formula in claim 1), and/or more than one solvent, and/or more than one emulsifier and/or more than one retardant, optionally together with other ingredients selected from perfumes and dyes.

4.- A method as claimed in any one of claims 1 to 3 in which the pyrethroid insecticides is either (a) a compound of formula (I) wherein R represents or in which R1 is halo, CF3 or CHF2O, R2 represents hydrogen or halo, n is 0 or 1, and Z and Z1 are each independently selected from halo, CF3 and methyl ; or Z(Z1)C= represents :

X represents hydrogen or halo, and X is H, CN or C?CH, in the form or individual isomers or mixtures thereof;
or (b) a compound of formula :

or in the form of individual isomers ir mixtures thereof;
or (c) a compound selected from flumethrin, bifenthrin, bioallethrin, S-bioallethrin, esbiothrin, resmethrin, bioremesthrin and acrinathrin.

5.- A method as claimed in any one of claims 1 to 4 wherein L
is less than 10.

6.- A method as claimed in claim 5 wherein L is less than 5.

7.- A method as claimed in any one of claims 1 to 6 wherein the amount of emulsifier present in the formulation is less than twice the amount of the evaporation retardant present.

8.- A method as claimed in claim 7 wherein the amount of emulsifier present in the formulation is less than the amount of the evaporation retardant present.

9.- A method as claimed in any one of claims 1 to 8 wherein the emulsifier is a non-ionic compound with an HLB
(hydrophilic/lipophilic balance) value of 8-18, or a mixture of non-ionic compounds, the mixture having a weighted average HLB value of 8-18.

10.- A method of claimed in any one of the preceding claims wherein the evaporation retardant is hexadecan-1-ol, octadecan-1-ol or a mixture thereof.