Insecticidal synergistic mixture of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioate and O-ethyl O-(2-chloro-4-bromophenyl)-S-n-propyl phosphorothioate
SUMMARY OF THE INVENTION 
     The present invention is directed to new insecticidal compositions which are useful in the kill and control of insects. The composition comprises a mixture of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioate and O-ethyl O-(2-chloro-4-bromophenyl)-S-n-propyl phosphorothioate. It has been found that the toxic ingredients of said compositions are mutually activating. 
     The O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioate employed in accordance with the teachings of the present invention is a solid material melting at ˜41°-42° C. The compound, its method of preparation and its insecticidal activity are taught in U.S. Pat. No. 3,244,586. 
     The O-ethyl O-(2-chloro-4-bromophenyl)-S-n-propyl phosphorothioate employed in accordance with the teachings of the present invention is a liquid material having a refractive index of n D   20  of 1.5466. The compound, its method of preparation and its insecticidal activity are taught in U.S. Pat. No. 3,992,533. 
     The new insecticidal composition of the present invention comprises about 1 part by weight of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioate and from about 1/66 to about 8 parts by weight of O-ethyl O-(2-chloro-4-bromophenyl)-S-n-propyl phosphorothioate, i.e. a ratio of about 66:1 to about 1:8. A preferred ratio is from about 4:1 to about 1:4 with the most preferred ratio being from about 2:1 to about 1:2. 
     The insecticidal composition of the present invention is espeically effective in the kill and control of a broad spectrum of insects. The compositions are particularly effective against insects which infest crops such as corn, tobacco and soybeans, with particular valuable results against insects which attack cotton. The compositions are effective as contact and stomach poisons and can therefore be employed for the control of stages of development of the insects such as eggs, larvae, nymphs, pupae and adults. The composition can be applied to a variety of insects of the biting, boring and sucking types. 
     Representative insects which can be killed and controlled by the presently claimed mixture include, for example, grape mealybug (Pseudococcus maritimus), thrips (Thysanopetra), such as Hercinothrips femoralis, beet bug (Piesma guadrata), red cotton bug (Dysdercus intermedius), bed bug (Cimex lectularius), assassin bug (Rhodnius prolixus) and Chagas&#39; bug (Triatoma infestans), the diamond-back moth (Plutella maculipennis), the gypsy moth (Lymantria dispar), the brown-tail moth (Euproctis chrysorrhoea), codling moth (Laspeyresia pomonella), tent caterpillar (Malacosoma neustria), cabbage moth (Mamestra brassicae), cutworm (Agrotis segetum), the large butterfly (Pieris brassicae), small winter moth (Cheimatobia brumata), green oak tortrix moth (Tortrix viridana), fall armyworm (Laphygma frugiperda), cotton worm (Prodenia litrua), ermine moth (Hyponomeuta padella), Mediterranean flour moth (Ephestia kuhniella), greater wax moth (Galleria mellonella), cotton bollworm (Heliothis zea), tobacco budworm (Heliothis virescens), beet armyworm (Spodoptera exigua), granary weevil (Sitophilus granarius=Calandra granaria), Colorado beetle (Leptinotarsa decemlineata), dock beetle (Gastrophysa viridula), mustard beetle (Phaedon cochleariae), blossom beetle (Meligethes aeneus), boll weevil (Authonomus grandis), raspberry beetle (Buturus tometosus), bean weevil (Bruchidius=Acanthoscelides obtectus), leather beetle (Dermestes frischi), khapra beetle (Trogoderma granarium), flour beetle (Tribolium castaneum), northern corn billbug (Calandra or Sitophilus zeamais), drugstore beetle (Stegobium paniceum), yellow mealworm (Tenebrio molitor), saw-toothed grain beetle (Oryzae-philus surinamensis), wireworms (Agriotes spec.), larvae of the cockchafer (Melolontha melolontha), German cockroach (Blattella germanica), American cockroach (Periplaneta americana), Maderia cockroach (Leucophaea or Rhyparobia maderae), oriental cockroach (Blatta orientalis), giant cockroach (Blaberus giganteus), black giant cockroach (Blaberus fuscus) and (Henschoutednia flexivitta), house cricket (Gryllus domesticus), eastern subterranean termite (Reticulitermes flavipes), garden ant (Lasius niger), vinegar fly (Drosophila melanogaster), Mediterranean fruit fly (Ceratitis capitata), house fly (Musca domestica), little house fly (Fannia canicularis), black blow fly (Phormia regina), bluebottle fly (Calliphora erythrocephala), stable fly (Stomoxys calcitrans), yellow fever mosquito (Aedes aegypti), northern house mosquito (Culexpinpiens) and the malaria mosquito (Anopheles stephensi). 
     Of these, the invention is especially valuable for kill and control of the cotton bollworm, tobacco budworm, codling moth, and the beet armyworm. 
     The present invention also comprises methods for controlling the above insects by contacting such organisms and/or their habitats with a pesticidally effective amount of the active compound mixture. For such uses the unmodified active materials of the present invention can be employed. However, the present invention embraces the use of an insecticidally-effective amount of the active materials in admixture with an inert material as an adjuvant or carrier therefor, in solid or liquid form. Thus, for example, the active mixture can be dispersed on a finely divided solid and employed therein as a dust. Also, the active mixture, as liquid concentrates or solid compositions comprising the active mixture, can be dispersed in water, typically with the aid of a wetting agent, and the resulting aqueous dispersion employed as a spray. In other procedures, the active mixture can be employed as a constituent of organic liquid compositions, oil-in-water and water-in-oil emulsions, or water dispersions, with or without the addition of wetting, dispersing, or emulsifying agents. 
     Suitable adjuvants of the foregoing type are well known to those skilled in the art. The methods of applying the solid or liquid pesticidal formulations similarly are well known to the skilled artisan. 
     As organic solvents used as extending agents there can be employed hydrocarbons, e.g. benzene, toluene, xylene, kerosene, diesel fuel, fuel oil, and petroleum naphtha, ketones such as acetone, methyl ethyl ketone and cyclohexanone, chlorinated hydrocarbons such as carbon tetrachloride, chloroform, trichloroethylene, and perchloroethylene, esters such as ethyl acetate, amyl acetate and butyl acetate, ethers, e.g., ethylene glycol monomethyl ether and diethylene glycol monomethyl ether, alcohols, e.g., methanol, ethanol, isopropanol, amyl alcohol, ethylene glycol, propylene glycol, butyl Carbitol acetate and glycerine. Mixtures of water and organic solvents, either as solutions or emulsions, can be employed. 
     The active mixtures can also be applied as aerosols, e.g., by dispersing them in air by means of a compressed gas such as dichlorodifluoromethane or trichlorofluoromethane and other such materials. 
     The active mixture of the present invention can also be applied with adjuvants or carriers such as talc, pyrophyllite, synthetic fine silica, attapulgus clay, kieselguhr, chalk, diatomaceous earth, lime, calcium carbonate, bentonite, fuller&#39;s earth, cottonseed hulls, wheat flour, soybean flour, pumice, tripoli, wood flour, walnut shell flour, redwood flour and lignin. 
     As stated, it is frequently desirable to incorporate a surface active agent in the compositions of the present invention. Such surface active or wetting agents are advantageously employed in both the solid and liquid compositions. The surface active agent can be anionic, cationic or nonionic in character. 
     Typical classes of surface active agents include alkyl sulfonate salts, alkylaryl sulfonate salts, alkylaryl polyether alcohols, fatty acid esters of polyhydric alcohols and the alkylene oxide addition products of such esters, and addition products of long chain mercaptans and alkylene oxides. Typical examples of such surface active agents include the sodium alkylbenzene sulfonates having 10 to 18 carbon atoms in the alkyl group, alkylphenol ethylene oxide condensation products, e.g., p-isooctylphenol condensed with 10 ethylene oxide units, soaps, e.g., sodium stearate and potassium oleate, sodium salt of propylnaphthalene sulfonic acid, di(2-ethylhexyl)-ester of sodium sulfosuccinic acid, sodium lauryl sulfate, sodium decane sulfonate, sodium salt of the sulfonated monoglyceride of coconut fatty acids, sorbitan sesquioleate, lauryl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, polyethylene glycol lauryl ether, polyethylene glycol esters of fatty acids and rosin acids, e.g., Ethofat 7 and 13, sodium N-methyl-N-oleyl taurate, Turkey Red Oil, sodium dibutyl naphthalene sulfonate, sodium lignin sulfonate, polyethylene glycol stearate, sodium dodecylbenzene sulfonate tertiary dodecyl polyethylene glycol thioether (nonionic 218), long chain ethylene oxide-propylene oxide condensation products, e.g., Pluronic 61 (molecular weight 1000), polyethylene glycol ester of tall oil acids, sodium octyl phenoxyethoxyethyl sulfate, tris(polyoxyethylene)sorbitan monostearate (Tween 60), and sodium dihexyl sulfosuccinate. 
     The concentration of the active mixtures in liquid formulations generally is from about 0.01 to about 95 percent by weight or more. Concentrations of from about 0.1 to about 50 weight percent are often employed. In formulations to be employed as concentrates, the active materials can be present in a concentration of from about 5 to about 98 weight percent. In dusts or dry formulations, the concentration of the active ingredient can be from about 0.01 to about 95 weight percent or more; concentrations of from about 0.1 to about 50 weight percent are often conveniently employed. The active compositions can also contain other compatible additaments, for example, plant growth regulants, pesticides and the like. 
     The present compositions can be applied by the use of power-dusters, boom and hand sprayers, spray-dusters and by other conventional means. The compositions can also be applied from airplanes as a dust or a spray. 
     The active mixtures of this invention are usually applied at an approximate rate of from about 1/16 pound to about 5 pounds or more per acre, but lower or higher rates may be appropriate in some cases. A preferred application rate is from 1/4 pound to about 2 pounds per acre. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following examples illustrate the present invention and the manner by which it can be practiced but, as such, should not be construed as limitations upon the overall scope of the same. 
     EXAMPLE I 
     A study was conducted to determine the effectiveness and synergistic response of various combinations of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioate and O-ethyl O-(2-chloro-4-bromophenyl)-S-n-propyl phosphorothioate in the control of Tobacco budworms. 
     Test solutions were prepared by admixing predetermined amounts of each of the above compounds in predetermined amounts of water containing predetermined amounts of acetone and Triton X155 surfactant. 
     Tobacco leaf discs, 3 inches in diameter were dipped into one of the above mixtures and placed in an open petri dish to dry. After the leaf discs were dry, 5 late second instar (approximately 3-day old) tobacco bud worms (Heliothis virescens) were placed in each dish and the dishes covered. All treatments were run in triplicate and on two different days. Mortality was recorded 48 hours after treatment with moribund larvae unable to crawl their own body length being counted as dead. In this test method, intoxication occurred through contact with and feeding upon treated plants. 
     The results of this study are set forth below in Table I. 
     
                                           TABLE I                                 
__________________________________________________________________________
Test                      Ratio of                                        
                               Expected                                   
                                    Actual                                
                                         Percent Increase Over            
No..sup.(1)                                                               
    Chemical.sup.(2)                                                      
          Amount                                                          
               Chemical.sup.(3)                                           
                     Amount                                               
                          A to B                                          
                               Control.sup.(4)                            
                                    Control                               
                                         Expected Control.sup.(5)         
__________________________________________________________________________
1   --    --   --    --   --   --   0    --                               
2   A     12.5 --    --   --   --   0    --                               
3   A     25   --    --   --   --   23   --                               
4   A     50   --    --   --   --   48   --                               
5   A     100  --    --   --   --   70   --                               
6   --    --   B     1.5  --   --   0    --                               
7   --    --   B     3.1  --   --   7    --                               
8   --    --   B     6.2  --   --   7    --                               
9   --    --   B     12.5 --   --   40   --                               
10  --    --   B     25   --   --   67   --                               
11  --    --   B     50   --   --   86   --                               
12  A     12.5 B     1.5  8:1   0   0    0                                
13  A     25   B     1.5  16:1 23   30   30                               
14  A     50   B     1.5  32:1 48   60   25                               
15  A     100  B     1.5  66:1 70   80   14                               
16  A     12.5 B     3.1  4:1   7   13   85                               
17  A     25   B     3.1  8:1  28   67   139                              
18  A     50   B     3.1  16:1 52   93   79                               
19  A     100  B     3.1  32:1 72   87   21                               
20  A     12.5 B     6.2  2:1   7   33   371                              
21  A     25   B     6.2  4:1  28   60   114                              
22  A     50   B     6.2  8:1  52   20   0                                
23  A     100  B     6.2  16:1 72   100  39                               
24  A     12.5 B     12.5 1:1  40   53   33                               
25  A     25   B     12.5 2:1  54   93   72                               
26  A     50   B     12.5 4:1  69   93   35                               
27  A     100  B     12.5 8:1  82   100  22                               
28  A     12.5 B     25   1:2  67   90   34                               
29  A     25   B     25   1:1  75   100  33                               
30  A     50   B     25   2:1  83   100  20                               
31  A     100  B     25   4:1  90   100  11                               
32  A     12.5 B     50   1:4  86   100  16                               
33  A     25   B     50   1:2  89   100  12                               
34  A     50   B     50   1:1  93   100  8                                
35  A     100  B     50   2:1  96   100  4                                
__________________________________________________________________________
 .sup.(1) Test Nos. 1-11 are control runs with Test 1 being a no chemical 
 control (surfactant/acetone/water alone).                                
 .sup.(2) Chemical A represents O,Odiethyl                                
 O(3,5,6-trichloro-2-pyridinyl)phosphorothioate.                          
 .sup.(3) Chemical B represents Oethyl O(2-chloro-4-bromophenyl)-S-n-propy
 phosphorothioate.                                                        
 ##STR1##                                                                 
 ##STR2##                                                                 
 
    
     EXAMPLE II 
     A study was conducted to determine the effectiveness and synergistic response of various combinations of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioate and O-ethyl O-(2-chloro-4-bromophenyl)-S-n-propyl phosphorothioate in the control of beet armyworm. 
     Test solutions were prepared by admixing predetermined amounts of each of the above compounds as setforth above in Example I. 
     Stands of young cotton plants were thoroughly wetted briefly with one of the above set forth compositions and the wetted plants permitted to dry. After the plants were dry, the leaves were cut off and placed in a petri dish. Five (5) live beet armyworm larvae (Spodoptera exigua) were placed in each dish. In identical operations, 5 live beet armyworm larvae were placed in each dish of control petri dishes containing untreated (surfactant/acetone/water only) cotton leaves. The dishes were maintained for a period of about 2 days under conditions favorable to the growth of the larvae. At the end of the 2-day period, all of the dishes were examined to determine the percent kill and control of the larvae. The results of this examination are set forth below in Table II. 
     
                                           TABLE II                                
__________________________________________________________________________
Test                      Ratio of                                        
                               Expected                                   
                                    Actual                                
                                         Percent Increase Over            
No..sup.(1)                                                               
    Chemical.sup.(2)                                                      
          Amount                                                          
               Chemical.sup.(3)                                           
                     Amount                                               
                          A to B                                          
                               Control.sup.(4)                            
                                    Control                               
                                         Expected Control.sup.(5)         
__________________________________________________________________________
1   --    --   --    --   --   --   0    --                               
2   A     3.1  --    --   --   --   0    --                               
3   A     6.2  --    --   --   --   20   --                               
4   A     12.5 --    --   --   --   60   --                               
5   --    --   B     1.5  --   --   0    --                               
6   --    --   B     3.1  --   --   0    --                               
7   --    --   B     6.2  --   --   0    --                               
8   --    --   B     12.5 --   --   7    --                               
9   --    --   B     25   --   --   73   --                               
10  A     3.1  B     1.5  2:1  0    7    &gt;100.sup.(6)                     
11  A     6.2  B     1.5  4:1  20   7     0                               
12  A     12.5 B     1.5  8:1  60   100   66                              
13  A     3.1  B     3.1  1:1  0    7    &gt;100.sup.(6)                     
14  A     6.2  B     3.1  2:1  20   27    35                              
15  A     12.5 B     3.1  4:1  60   93    55                              
16  A     3.1  B     6.2  1:2  0    20   &gt;100.sup.(6)                     
17  A     6.2  B     6.2  1:1  20   60   200                              
18  A     12.5 B     6.2  2:1  60   87    45                              
19  A     3.1  B     12.5 1:4  7    47   571                              
20  A     6.2  B     12.5 1:2  26   27    4                               
21  A     12.5 B     12.5 1:1  61   87    43                              
22  A     3.1  B     25   1:8  25   80   220                              
23  A     6.2  B     25   1:4  40   93   133                              
24  A     12.5 B     25   1:2  70   100   43                              
__________________________________________________________________________
 .sup.(1) Test Nos. 1-9 are control runs with Test 1 being a no chemical  
 control (surfactant/acetone/water alone).                                
 .sup.(2) Chemical A represents O,Odiethyl                                
 O(3,5,6-trichloro-2-pyridinyl)phosphorothioate.                          
 .sup.(3) Chemical B represents Oethyl O(2-chloro-4-bromophenyl)-S-n-propy
 phosphorothioate.                                                        
 ##STR3##                                                                 
 ##STR4##                                                                 
 .sup.(6) Percent increase too great to be computed.                      
 
    
     EXAMPLE III 
     A study was conducted to determine the effectiveness and synergistic response of various combinations of O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl)phosphorothioate and O-ethyl O-(2-chloro-4-bromophenyl)-S-n-propyl phosphorothioate in the control of codling moths (Laspeyresia pomonella). 
     Test solutions were prepared by admixing predetermined amounts of each of the above compounds as set forth in Example I. 
     Sheets containing egg masses of codling moths are pinned to apples and the egg sheets and apples are drenched with an aqueous dispersion of one of the hereinafter set forth compounds. Separate egg masses on apples were also treated with the control mixture. The egg masses/apples were incubated under conditions conducive to the hatching of the eggs and the growth of the larvae therefrom. At the same time, a water/acetone/surfactant mixture containing none of the compound mixtures was also prepared to serve as a control. Eight days after treatment, the apples were examined for the presence of larvae. Counts of the number of larvae penetration in the treated fruit was compared to the number present in the control to determine the present control obtained with the test compounds. The results of the examination are set forth below in Table III. 
     
                                           TABLE III                               
__________________________________________________________________________
Test                      Ratio of                                        
                               Expected                                   
                                    Actual                                
                                         Percent Increase Over            
No..sup.(1)                                                               
    Chemical.sup.(2)                                                      
          Amount                                                          
               Chemical.sup.(3)                                           
                     Amount                                               
                          A to B                                          
                               Control.sup.(4)                            
                                    Control                               
                                         Expected Control.sup.(5)         
__________________________________________________________________________
1   --    --   --    --   --   --   0    --                               
2   A     3.1  --    --   --   --   0    --                               
3   A     6.2  --    --   --   --   50   --                               
4   A     12.5 --    --   --   --   67   --                               
5   A     25   --    --   --   --   79   --                               
6   --    --   B     1.5  --   --   0    --                               
7   --    --   B     3.1  --   --   0    --                               
8   --    --   B     6.2  --   --   0    --                               
9   --    --   B     12.5 --   --   36   --                               
10  --    --   B     25   --   --   43   --                               
11  A     3.1  B     1.5  2:1   0   37   &gt;100.sup.(6)                     
12  A     6.2  B     1.5  4:1  50   55    10                              
13  A     12.5 B     1.5  8:1  67   60    0                               
14  A     25   B     1.5  16:1 79   87    10                              
15  A     3.1  B     3.1  1:1   0   38   &gt;100.sup.(6)                     
16  A     6.2  B     3.1  2:1  50   54    8                               
17  A     12.5 B     3.1  4:1  67   74    10                              
18  A     25   B     3.1  8:1  79   87    10                              
19  A     3.1  B     6.2  1:2   0   61   &gt;100.sup.(6)                     
20  A     6.2  B     6.2  1:1  50   70    40                              
21  A     12.5 B     6.2  2:1  67   71    6                               
22  A     25   B     6.2  4:1  79   84    6                               
23  A     3.1  B     12.5 1:4  36   66    83                              
24  A     6.2  B     12.5 1:2  68   69    1                               
25  A     12.5 B     12.5 1:1  79   84    6                               
26  A     25   B     12.5 2:1  87   99    14                              
27  A     3.1  B     25   1:8  43   64    49                              
28  A     6.2  B     25   1:4  72   85    18                              
29  A     12.5 B     25   1:2  81   89    10                              
30  A     25   B     25   1:1  88   97    10                              
__________________________________________________________________________
 .sup.(1) Test Nos. 1-10 are control runs with Test 1 being a no chemical 
 control (surfactant/acetone/water alone).                                
 .sup.(2) Chemical A represents O,Odiethyl                                
 O(3,5,6-trichloro-2-pyridinyl)phosphorothioate.                          
 .sup.(3) Chemical B represents Oethyl O(2-chloro-4-bromophenyl)-S-n-propy
 phosphorothioate.                                                        
 ##STR5##                                                                 
 ##STR6##                                                                 
 .sup.(6) Percent increase too great to be computed.                      
 
    
     Data from Tables I, II and III illustrates that better control was obtained employing the two toxicants together than would be expected from the results obtained from employing each of the two toxicants alone. These data are obtained according to the technique described in Colby, &#34;Calculating Synergistic and Antagonistic Responses of Herbicide Combinations&#34;, Weeds, Vol. 15 (1967) pages 20-22 and Colby, &#34;Greenhouse Evaluation of Herbicide Combinations&#34;, Proc. NEWCC, No. 19, pages 312-320.