Patent Publication Number: US-5290770-A

Title: Synergistic compositions

Description:
This is a continuation of U.S. Ser. No. 07/796,707, filed Nov. 21, 1991, now abandoned, which is a continuation of U.S. Ser. No. 07/672,734, filed Mar. 21, 1991, now U.S. Pat. No. 5,096,895, which is a continuation of Ser. No. 07/432,989, filed on Nov. 6, 1989, now abandoned, which is a division of U.S. Ser. No. 06/575,486, filed Jan. 31, 1984, now U.S. Pat. No. 4,897,386, which is a division of U.S. Ser. No. 06/391,455, filed Jun. 23, 1982, now abandoned, which is a continuation of U.S. Ser. No. 05/863,738, filed Dec. 23, 1977, now abandoned. 
    
    
     This invention relates to novel potentiating compositions, their preparation, formulations containing them, the preparation of such formulations and to their use for the control of pests of the sub-Orders Ixodoidea and Sarcoptiformes. 
     Pyrethroids embraced by formula (I): ##STR2## are known from UK 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. 
     Organophosphorus pesticides are used in both the agricultural and veterinary fields with varying degrees of success. Some of these substances are common to both fields such as diazinon and malathion whilst others have been solely employed in the agricultural field, for example fenitrothion. In recent years resistance to organophosphorus 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. 058-237/1975, that potentiation of activity occurs between a pyrethroid of formula (I) and certain organophosphorus compounds against Insects and certain Mites of agricultural importance. Employing such potentiating compositions, renders the use of pyrethroids of formula (I) more economic. The Japanese publication also suggests that the potentiation is due to the interaction between the inhibition of the enzyme acetyl-cholinesterase by the organophosphorus 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 organophosphorus compounds against pests of veterinary importance which are resistant to conventional organophosphorus compounds and which belong to the sub-Orders Ixodoidea and Sarcoptiformes. It is believed that the potentiation is due to the inhibition by the organophosphorus 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 knowledge of potentiation in another group. This unpredictability is demonstrated by the absence of potentiation of insecticidal activity between a compound of formula (I) and an organophosphorus compound in respect of Insects of veterinary importance. (See Tables 6 to 9 below). 
     The pyrethroid for use in the present invention is selected from the esters embraced by formula (I) defined above. Structural formula (I) is intended to encompass all the possible geometric and optical isomers. More particularly the acid moiety of the ester may be selected from the (+)-cis-isomer, the (+)-trans-isomer, the (±)-cis-isomer, the (±)-trans-isomer and the (±)-cis-trans-isomer; the stereochemistry referring to that of the cyclopropane ring. 
     The preferred pyrethroid of this invention is 3-phenoxybenzyl-(±)-cis,trans-2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane-1-carboxylate (permethrin). 
     The activity of these esters against pests of the sub-Orders Ixodoidea and Sarcoptiformes is potentiated when used in combination with at least one organophosphorus compound. 
     More particularly, the esters may be used in combination with phosphate and phosphorothioate compounds possessing intrinsic acaricidal activity. The organophosphorus compounds found to be effective are: 
     O,O-diethyl-O-(3-chloro-4-methyl-7-coumarinyl) phosphorothioate (coumaphos); 
     O,O-diethyl-O-(2,5-dichloro-4-bromophenyl) phosphorothioate (bromophos-Ethyl); 
     2,3-p-dioxanedithiol-S,S-bis, O,O-diethyl phosphorodithioate (dioxathion), 
     O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate (chlorpyrifos); 
     O,O,0&#39;,0&#39;-tetraethyl, S,S&#39;-methylenediphosphorodithioate (ethion); 
     3-(Dimethoxyphosphinyloxy)-N-dimethyl-ciscrotonamide (dicrotophos); 
     cis-1-methyl-2-(1-phenylethoxycarbonyl)vinylphosphate (crotoxyphos); 
     O-ethyl-O-(quinol-8-yl)phenylphosphorothioate (oxinothiophos); 
     (S-{5,7-dichlorobenzoxazol-2-yl-methyl}-O,O-diethyl phosphorodithioate) (benoxaphos); 
     S-[{(4-chlorophenyl)-thio]methyl}-O,O-diethyl phosphorodithioate (carbophenothion); 
     S-{(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)-methyl}O,O-dimethylphosphorodithioate (phosmet); 
     2-Chloro-1-(2,4-dichlorophenyl)vinyldiethylphosphate (chlorfenvinphos) 
     and a 1:1 weight by weight mixture of chlorofenvinphos and dioxathion. 
     Particularly high potentiation is achieved with combinations containing coumaphos, chlorfenvinphos, diazinon, ethion and the mixture of dioxathion and chlorfenvinphos. 
     The potentiating compositions of this invention are highly effective against strains of acarines which are susceptible to conventional organophosphorus acaricides as well as to those strains which are resistant to conventional organophosphorus acaricides such as Boophilus microplus (Can.) and B. decoloratus (Koch) and in addition those strains resistant to pyrethroids. The compositions of this invention may therefore be used to control acarine ectoparasites of animals, particularly those ticks of the genera Boophilus, Rhipicephalus, Amblyomma, Hyalomma, Ixodes, Haemaphysalis, Dermacentor, and Anocentor, and mites of veterinary importance for example the sheep scab mite Psoroptes ovis, and other ectoparasites of the sub-Orders Ixodoidea and Sarcoptiformes. 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 means of a powder gun by hand application from suitable containers or 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 animals. 
     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 organophosphorus 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&#39;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, syringe or ladle or any other method known in the art. 
     A composition of the present invention preferably contains (5-95%) of a defined pyrethroid for example one selected from structural formula (I) and between (5-95%) of an organophosphorus compound defined hereinabove. The concentration of a composition applied to the pests or to their environment may be in the range of (0.0001-20%). 
     It will be appreciated from the foregoing that what we will claim may comprise any novel feature described herein, principally and not exclusively, for example: 
     (a) A novel composition comprising an ester of formula (I) in combination with at least one organo-phosphorus compound; 
     (b) A pesticidal formulation comprising a composition as defined in paragraph (a) together with a carrier therefor; 
     (c) A method of producing such a formulation; and 
     (d) A method of controlling veterinary ectoparasites of the sub-Orders Ixodoidea and Sarcoptiformes comprising the application to the ectoparasite or its environment, a composition or formulation as defined in paragraph (a) or (b). 
    
    
     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 organophosphorus compound 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 organophosphorus compound 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 dorsal side down on doublesided 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 % 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: ##EQU1## 
     The FOP figures for the IR99 values were calculated in the same way. 
     
                                           TABLE 1                                 
__________________________________________________________________________
IR90/99 Values for the Ixodicides alone and Compositions                  
of these with Permethrin at various Ratios                                
PERMETHRIN                                                                
         IXODICIDE                                                        
COMPOSITE                                                                 
         ALONE  RATIO 1:1                                                 
                      RATIO 1:5                                           
                             RATIO 5:1                                    
                                   RATIO 10:1                             
                                          RATIO 20:1                      
WITH     IR90                                                             
             IR99                                                         
                IR90                                                      
                   IR99                                                   
                      IR90                                                
                         IR99                                             
                             IR90                                         
                                IR99                                      
                                   IR90                                   
                                      IR99                                
                                          IR90                            
                                             IR99                         
__________________________________________________________________________
Coumaphos                                                                 
         1.0 -- 0.016                                                     
                   0.024                                                  
                      .0016                                               
                         .0030                                            
                             0.038                                        
                                0.092                                     
Composition A                                                             
         0.75                                                             
             2.6                                                          
                0.011                                                     
                   0.017                                                  
                      .0031                                               
                         .0053                                            
                             0.060                                        
                                0.15                                      
Bromophos Ethyl                                                           
         0.18                                                             
             0.38                                                         
                0.010                                                     
                   0.016                                                  
                      .0058                                               
                         .0098                                            
                             0.064                                        
                                0.12                                      
Diazinon 1.0 -- 0.095                                                     
                   0.21                                                   
                      .0030                                               
                         .0056                                            
                             0.017                                        
                                0.038                                     
Dioxathion                                                                
         1.0 -- 0.016                                                     
                   0.038                                                  
                      .0028                                               
                         0.023                                            
                             0.044                                        
                                0.060                                     
Chlorpyrifos                                                              
          0.085                                                           
             0.24                                                         
                0.008                                                     
                   0.014                                                  
                      .0046                                               
                         .0062                                            
                             0.020                                        
                                0.024                                     
Ethion   0.14                                                             
             0.23                                                         
                0.015                                                     
                   0.024                                                  
                      .0032                                               
                         .0055                                            
                             0.099                                        
                                0.054                                     
Dicrotophos                                                               
         1.0 -- 0.063                                                     
                   0.15                                                   
                      .0080                                               
                         0.016                                            
                             0.044                                        
                                0.094                                     
Chlorfenvinphos                                                           
         0.15                                                             
             0.42                                                         
                0.015                                                     
                   0.024                                                  
                      .0015                                               
                         .0030                                            
                             0.018                                        
                                0.085                                     
                                   0.043                                  
                                      0.070                               
                                          0.067                           
                                             0.096                        
__________________________________________________________________________
 Composition A: A 1:1, weight by weight mixture of Chlorfenvinphos and    
 Dioxathion                                                               
 Key: -- Ratio Ixodicide/Permethrin                                       
 
    
     
                                           TABLE 2                                 
__________________________________________________________________________
Factors of Potentiation of composites of                                  
certain Ixodicides and Permethrin                                         
PERMETHRIN                                                                
COMPOSITE   RATIO 1:1                                                     
                   RATIO 1:5                                              
                          RATIO 5:1                                       
                                  RATIO 10:1                              
                                         RATIO 20:1                       
WITH        IR90                                                          
                IR99                                                      
                   IR90                                                   
                       IR99                                               
                          IR90 IR99                                       
                                  IR90                                    
                                     IR99                                 
                                         IR90                             
                                            IR99                          
__________________________________________________________________________
COUMAPHOS   &gt;3.9                                                          
                -- &gt;8.1                                                   
                       -- &gt;1.8 --                                         
COMPOSITION A                                                             
            5.5 7.3                                                       
                   4.2 4.8                                                
                          3.8  3.5                                        
BROMOPHOS ETHYL                                                           
            4.9 6.1                                                       
                   2.1 2.6                                                
                          1.8  2.0                                        
DIAZINON    &gt;0.7                                                          
                -- &gt;4.5                                                   
                       -- &gt;14.6                                           
                               --                                         
DIOXATHION  &gt;3.9                                                          
                -- &gt;4.7                                                   
                       -- &gt;5.6 --                                         
CHLORPYRIFOS                                                              
            4.6 6.0                                                       
                   2.5 3.8                                                
                          3.4  7.3                                        
ETHION      3.0 3.5                                                       
                   3.8 4.2                                                
                          3.0  3.1                                        
DICROTOPHOS &gt;1.0                                                          
                -- &gt;1.6                                                   
                       -- &gt;5.6 --                                         
CHLORFENVINPHOS                                                           
            3.1 4.1                                                       
                   8.1 8.1                                                
                          5.7  3.0                                        
                                  2.8                                     
                                     4.6 2.0                              
                                            3.8                           
__________________________________________________________________________
 Composition A: A 1:1, weight by weight mixture of Chlorfenvinphos and    
 Dioxanthion                                                              
 Key: -- Ratio Ixodicide/Permethrin                                       
 
    
     EXAMPLE 3 
     Miscible-Oil Formulations 
     
         ______________________________________                                    
            20:1 1:1      1:20                                            
______________________________________                                    
Dioxathion    20.0   10.5      1.0 pts. by wt.                            
Permethrin     1.0   10.5     20.0 &#34;                                      
Esso Solvent 200                                                          
              59.0   54.0     49.0 &#34;                                      
Ethylan KEO   20.0   20.0     20.0 &#34;                                      
Cyclohexanone --      5.0     10.0                                        
              100.0  100.0    100.0                                       
______________________________________                                    
 
    
     Ethylan KEO is an emulsifying agent which is a nonyl phenol ethoxylate condensate with an ethylene oxide average chain length of 9.5 mols, supplied by Lankro Chemicals Ltd. 
     Esso Solvent 200 is a mobile oil which consists of 95% of aromatic hydrocarbons. 
     EXAMPLE 4 
     Dusting Powder Formulations 
     
         ______________________________________                                    
         20:1  1:1       1:20                                             
______________________________________                                    
Coumaphos  0.01    0.10      0.20  pts. by wt.                            
Permethrin 0.20    0.10      0.01  &#34;                                      
Talc       99.79   99.8      99.79 &#34;                                      
           100.0   100.0     100.0                                        
______________________________________                                    
 
    
     EXAMPLE 5 
     Wettable Powder Formulations 
     
         ______________________________________                                    
              w/w         w/w     w/w                                     
______________________________________                                    
Coumaphos     1.0%        15.0%   40.0%                                   
Permethrin    20.0        15.0    2.0                                     
Diatomaceous Earth                                                        
              76.5        50.0    --                                      
Kaolin        --          17.5    54.0                                    
Dispersing Agent                                                          
              2.0         2.0     3.0                                     
Wetting Agent 0.5         0.5     1.0                                     
              100.0       100.0   100.0                                   
______________________________________                                    
              w/w         w/w                                             
______________________________________                                    
Ethion        2.0         25.0                                            
Permethrin    20.0        1.5                                             
Diatomaceous Earth                                                        
              60.5        36.0                                            
Fullers Earth 15.0        35.0                                            
Dispersing Agent                                                          
              2.0         2.0                                             
Wetting Agent 0.5         0.5                                             
              100.0       100.0                                           
______________________________________                                    
 
    
     EXAMPLE 6 
     Pressure-Pack Formulations 
     In the following examples one of three pesticide mixtures may be used: 
     Mixture 1 
     Dioxathion: 10 parts by weight 
     Chlorfenvinphos: 10 parts by weight 
     Permethrin: 1 part by weight 
     Mixture 2 
     Dioxathion: 0.5 parts by weight 
     Chlorfenvinphos: 0.5 parts by weight 
     Permethrin: 1 part by weight 
     Mixture 3 
     Dioxathion: 0.5 parts by weight 
     Chlorfenvinphos: 0.5 parts by weight 
     Permethrin: 20 parts by weight. 
     The above pesticide mixtures may be employed to formulate pressure packs containing between 0.0001% w/w and 20% w/w of each pesticide mixture as illustrated by the following examples: 
     
         ______________________________________                                    
Example A                                                                 
______________________________________                                    
Pesticide mixture        0.0001% w/w                                      
(either No. 1, 2 or 3 above)                                              
Odourless kerosene      10.0000% w/w                                      
Methyl chloroform       29.9999% w/w                                      
50/50 mixture of trichlorofluoromethane                                   
                        60.0000% w/w                                      
and dichlorodifluoromethane                                               
                        100.0000% w/w                                     
______________________________________                                    
 
    
     
         ______________________________________                                    
Example B                                                                 
______________________________________                                    
Pesticide mixture   20% w/w                                               
(either No. 1, 2 or 3 above)                                              
Methyl chloroform   50% w/w                                               
Dichlorodifluoromethane                                                   
                    30% w/w                                               
                    100% w/w                                              
______________________________________                                    
 
    
     EXAMPLE 7 
     Highly tick susceptible cattle were placed in tick stalls and artifically infested with 0.25 g of B. microplus (Biarra strain) larvae before and after treatment. Twenty-four days after introduction the animals were divided into four groups and power-hand sprayed with 36 liters of wash per animal. The washes contained the following concentrations of active ingredients: 
     Group 1: 500 ppm Ethion 
     Group 2: 100 ppm permethrin 
     Group 3: 100 ppm permethrin and 500 ppm Ethion 
     Group 4: 50 ppm permethrin and 500 ppm Ethion. 
     Engorged female ticks were collected daily from the washing baskets and counted. The results are illustrated in Table 5. 
     EXAMPLE 8 
     Engorged female ticks of the Biarra strain of B. microplus were immersed in serial ranges of concentrations of certain ixodicides alone. The ticks were then dried and stuck, dorsal side down, on double-sided sellotape. After 14 days the numbers of ticks laying viable egg batches were determined and the percentage plotted against concentration and a regression line drawn. The IR90/99 values were then determined as in Example 1. Having thus established the IR90/99 values for each of the chemicals under test equitoxic mixtures each comprising permethrin with one of the other ixodicides were prepared at the ratio of the IR99 values obtained. The master solutions were then diluted with water to the required range for the immersion test. 
     The results are illustrated in Table 10. 
     
                                           TABLE 6                                 
__________________________________________________________________________
LC50 values of individual organophosphorus                                
insecticides and compositions of these with                               
permethrin obtained both theoretically and                                
by experiment against Musca domestica                                     
(CTB strain) (ratio 1:1)                                                  
         Experimental   Calculated                                        
                LC50 Mixture   LC50 Mixture                               
         LC50 Alone                                                       
                as permethrin                                             
                        LC50 Total                                        
                               as permethrin                              
                                       Factor of                          
Compound (μg/♀)                                                 
                (μg/♀)                                          
                        (μg/♀)                                  
                               (μg/♀)                           
                                       Potentiation                       
__________________________________________________________________________
Permethrin                                                                
         0.027  --      --     --      --                                 
Bromophos ethyl                                                           
         0.102  0.029   0.043  0.021   0.74                               
Chlorpyrifos                                                              
         0.094  0.025   0.042  0.021   0.84                               
Bromophos                                                                 
         0.114  0.021   0.043  0.022   1.02                               
Malathion                                                                 
         1.349  0.036   0.053  0.026   0.73                               
Diazinon 0.041  0.025   0.032  0.016   0.66                               
__________________________________________________________________________
 LC50 is the minimum lethal dose expressed in μg required to kill 50% o
 the flies                                                                
 
    
     
                                           TABLE 7                                 
__________________________________________________________________________
LC95 values of individual organophosphorus                                
insecticides and compositions of these with                               
permethrin obtained both theoretically and                                
by experiment against Musca domestica                                     
(CTB strain) (ratio 1:1)                                                  
         Experimental   Calculated                                        
                LC95 Mixture   LC95 Mixture                               
         LC95 Alone                                                       
                as permethrin                                             
                        LC95 Total                                        
                               as permethrin                              
                                       Factor of                          
Compound (μg/♀)                                                 
                (μg/♀)                                          
                        (μg/♀)                                  
                               (μg/♀)                           
                                       Potentiation                       
__________________________________________________________________________
Permethrin                                                                
         0.054  --      --     --      --                                 
Bromophos ethyl                                                           
         0.170  0.097   0.082  0.041   0.43                               
Chlorpyrifos                                                              
         0.161  0.083   0.081  0.041   0.49                               
Bromophos                                                                 
         0.241  0.063   0.088  0.044   0.70                               
Malathion                                                                 
         3.671  0.105   0.107  0.053   0.51                               
Diazinon 0.160  0.066   0.081  0.040   0.61                               
__________________________________________________________________________
 LC95 is the minimum lethal dose expressed in μg required to kill 95% o
 the flies                                                                
 
    
     
                                           TABLE 8                                 
__________________________________________________________________________
LD50 values for individual organophosphorus                               
insecticides and compositions of these with                               
permethrin at various ratios against Musca                                
domestica (Piggery II strain)                                             
            Ratio 1:1        Ratio 1:10 (permethrin/OP)                   
                                              Ratio 1:25 (permethrin/OP)  
        LD50           Calculated       Calculated       Calculated       
Compound                                                                  
        (μ/♀)                                                   
            Calculated                                                    
                  observed                                                
                       observed                                           
                             Calculated                                   
                                   observed                               
                                        observed                          
                                              Calculated                  
                                                    observed              
                                                         observed         
__________________________________________________________________________
Permethrin                                                                
        0.235                                                             
            --    --   --    --    --   --    --    --   --               
Dimethoate                                                                
        0.179                                                             
            0.20  0.20 1.0   0.18  0.13 1.4   --    --   --               
Diazinon                                                                  
        2.075                                                             
            0.41  0.35 1.2   1.2   0.89 1.4   --    --   --               
Malathion                                                                 
        41.70                                                             
            0.46  0.42 1.1   2.45  2.49 1.0   5.36  3.0  1.8              
Chlorpyrifos                                                              
        2.171                                                             
            0.41  0.38 1.1   1.25  0.76 1.7   --    --   --               
Bromophos                                                                 
        2.663                                                             
            0.42  0.39 1.1   1.38  0.50 2.8   --    --   --               
ethyl                                                                     
Pirimiphos                                                                
        5.130                                                             
            0.44  0.38 1.2   1.78  1.22 1.5   2.85  1.77 1.6              
methyl                                                                    
__________________________________________________________________________
 LD50 is the minimum lethal dose expressed in μg required to kill 50% o
 the flies                                                                
 OP = organophosphorus compound                                           
 ##STR3##                                                                 
 
    
     
                                           TABLE 9                                 
__________________________________________________________________________
LD95 values for individual organophosphorus                               
insecticides and compositions of these with                               
permethrin at various ratios against Musca                                
domestica (Piggery II strain)                                             
            Ratio 1:1        Ratio 1:10 (permethrin/OP)                   
                                              Ratio 1:25 (permethrin/OP)  
        LD95           Calculated       Calculated       Calculated       
Compound                                                                  
        (μg/♀)                                                  
            Calculated                                                    
                  observed                                                
                       observed                                           
                             Calculated                                   
                                   observed                               
                                        observed                          
                                              Calculated                  
                                                    observed              
                                                         observed         
__________________________________________________________________________
Permethrin                                                                
        0.63                                                              
            --    --   --    --    --   --    --    --   --               
Dimethoate                                                                
        0.66                                                              
            0.65  0.53 1.2   0.66  0.62 1.1   --    --   --               
Diazinon                                                                  
        5.12                                                              
            1.16  1.06 1.1   3.11  2.84 1.1   --    --   --               
Malathion                                                                 
        177.5                                                             
            1.30  1.03 1.3   6.70  9.00 0.7   15.05 8.00 1.9              
Chlorpyrifos                                                              
        10.66                                                             
            1.23  0.85 1.5   4.36  1.79 2.4   --    --   --               
Bromophos                                                                 
        11.62                                                             
            1.24  0.91 1.4   4.50  1.82 2.5   --    --   --               
ethyl                                                                     
Pirimiphos                                                                
        15.6                                                              
            1.26  0.91 1.4   4.92  3.28 1.5    8.15 5.02 1.6              
methyl                                                                    
__________________________________________________________________________
 LD95 is the minimum lethal dose expressed in μg required to kill 95% o
 the flies                                                                
 OP = organophosphorus compound                                           
 ##STR4##                                                                 
 
    
     
                                           TABLE 10                                
__________________________________________________________________________
The activity of equitoxic mixtures of certain organo-                     
phosphorus ixodicides with permethrin against viable                      
oviposition of engorged female ticks of the Biarra                        
strain of B. microplus                                                    
                EQUITOXIC MIXTURE                                         
Permethrin                                                                
         ALONE  Expected Value                                            
                        Actual Value                                      
                               Factor of Potentiation                     
Composite with                                                            
         IR90                                                             
             IR99                                                         
                IR90                                                      
                    IR99                                                  
                        IR90                                              
                           IR99                                           
                               IR90 IR99                                  
__________________________________________________________________________
Ethion   0.14                                                             
             0.23                                                         
                0.10                                                      
                    0.18                                                  
                        0.012                                             
                           0.024                                          
                               8.3  7.5                                   
Chlorfenvinphos                                                           
         0.15                                                             
             0.42                                                         
                0.11                                                      
                    0.28                                                  
                        0.025                                             
                           0.059                                          
                               4.4  4.7                                   
Permethrin                                                                
          0.066                                                           
             0.13                                                         
__________________________________________________________________________
 ##STR5##                                                                 
 IR90 = concentration at which 90% inhibition of egg laying occurs        
 IR99 = concentration at which 99% inhibition of egg laying occurs        
 
    
     EXAMPLE 9 
     
         ______________________________________                                    
Aqueous Suspension Formulations                                           
                 % w/w                                                    
                 (a)   (b)      (c)                                       
______________________________________                                    
Permethrin         1.0     8.0      20.0                                  
Coumaphos          20.0    8.0      1.0                                   
Sodium Dioctyl Sulphosuccinate                                            
                   0.2     0.2      0.2                                   
Xanthan Gum        0.3     0.4      0.3                                   
Water              78.5    83.4     78.5                                  
                   100.0   100.0    100.0                                 
______________________________________                                    
 
    
     EXAMPLE 10 
     
         ______________________________________                                    
Diluent Free Formulations                                                 
           % w/w                                                          
           (a)       (b)     (c)                                          
______________________________________                                    
Permethrin   3.5         38.0    72.0                                     
Diazinon     70.0        38.0    3.6                                      
Epichlorhydrin                                                            
             7.0         4.0     0.4                                      
Ethylan KEO  19.5        20.0    24.0                                     
             100.0       100.0   100.0                                    
______________________________________                                    
 
    
     Ethylan KEO is an emulsifying agent which is a nonyl phenol ethoxylate condensate with an ethylene oxide average chain length of 9.5 mols, supplied by Lankro Chemicals Ltd. 
     REFERENCE EXAMPLE A 
     Mixtures of permethrin in combination with various organophosphorus compounds were prepared at 1:1, 1:10 and 1:25 ratios (ratio permethrin to organophosphorus compound). Solutions of the pesticides alone were similarly prepared. 
     The individual pesticides and the mixtures were diluted appropriately and applied by means of a microsyringe to the dorsal thorax of female CTB or Piggery II strain Musca domestica flies. This topical application technique was performed on twenty females flies for each concentration of each mixture. The flies were then placed in a cardboard carton with access to sugar water for one day in order to assess mortality. Each concentration of each mixture was tested five times in a linked sequence over a period of several weeks. 
     The LC50 and LC95 value of each mixture was determined by means of probit analysis. A theoretical LC50 and LC95 value was calculated for each mixture by means of the equation of the harmonic mean. 
     The theoretical and experimental values were then compared in order to give factors of potentiation values. 
     The results are given in Tables 6 to 9, which indicate that little or no potentiation was observed.