Insecticidal composition and method for combatting aphids
This application is a continuation, of application Ser. No. 815,619, filed Jan. 2, 1986, abandoned. 
    
    
     This invention relates to insecticidal compositions and to a method for combatting aphid. 
     It is known that the use of insecticides suffers from disadvantages because of the toxicity of insecticides. 
     From PCT application WO-A-8204249 it is known to use both E-β-farnesene, an aphid alarm pheromone, and an insecticide (aphicide). Practical examples of this combination are not disclosed in said PCT-application. In Entomoligia Experimentalis et Applicata, vol. 27, no. 2, 1980, blz. 199-201, &#34;Ned. Entomol. Ver., Amsterdam&#34;, A potential application of aphid alarm pheromones&#34; by D. C. Griffiths en J. A. Pickett, which does disclose a practical embodiment of this combination, the two materials are used successively and not in one composition. 
     The insecticidal composition according to the invention contains 0.05-4.0 percent by weight of an alarm pheromone for aphids and an aphid insecticide in an amount which is at least about 10% less than the minimum usual amount for said insecticide in an aphicidal composition. 
     An advantage of the present invention is that by using an alarm pheromone for aphids in combination with an insecticide, the amount of insecticide can be considerably less, i.e. at least about 10% less than the minimum usual amount of said insecticide in an aphicidal composition. 
     The activity of the alarm pheromone is due to the fact that the aphids begin to move as a result of the agitation caused by the alarm pheromone, whereby the contact with the insecticide is promoted and furthermore the aphids fall from the plants in great numbers and the majority will not find again the plant; in addition, the agitation brought about by the alarm pheromone causes as such inactivation (&#34;knock down&#34;) of the insects, after which the insects often die. 
     In general when using the present mixture of aphid insecticide and alarm pheromone a faster killing can be observed than when using only the insecticide. 
     Furthermore, the present mixture is active against aphid strains which are resistant to organic phosphates, carbamates and pyrethroids, even though the amount of insecticide in the mixture is less than the usual amount. 
     In addition, the replacement of part of the insecticide by an alarm pheromone generally means a cost saving such as in the case of the combination pyrethrum/farnesene. 
     As alarm pheromones for aphids E-β-farnesene and α-pinene may be mentioned. 
     Preferably the amount of the aphid insecticide in said composition is about 20% less than the minimum amount which is usual for said insecticide. 
     When using pyrethrum (a mixture of natural pyrethroids) as the aphid insecticide, this insecticide is used in an amount which is at least about 10% less than 0.06 percent by weight, the minimum usual percentage of pyrethrum in aphidical compositions. 
     When using a synthetic pyrethroid as the aphid insecticide (e.g. tetrametrin, alletrin, permetrin, cypermetrin, deltametrin) as the aphid insecticide, this insecticide is used in an amount which is at least about 10% less than 0.03% by weight, the minimum usual percentage of a synthetic pyrethroid in aphicidal compositions. 
     When using organic chloro compounds, organic phosphates or carbamates (e.g. endosulfan, fenitrothion, butocarboxim, bromofos, DDVP, diazinon, malathion, pirimicarb, propoxur and ethiofencarb) as the aphid insecticides, these insecticides are used in an amount which is at least about 10% less than 0.05% by weight, the minimum usual percentage of these insecticides in aphicidal compositions. 
     According to the invention the insecticide content in the aphicidal composition generally can be lowered by about 75% or more without a disadvantaageous influence on the activity. For example the minimum usual percentage of synthetic pyrethroids in aphicidal compositions is about 0.03% and in the present mixtures this percentage can be lowered to about 0.01% without detracting from the activity. For the combination pyrethrum/farnesene the lower limit for the amount of pyrethrum in an aerosol formulation is only 0.00025% and the practical upper limit is 0.03% (more than 0.03% offers no advantages). 
    
    
     EXAMPLES 
     Hereinafter a number of spray tests with aphids are carried out. 
     Spraying was carried out with aerosol cans containing water-based compositions, of which the data concerning the amounts of pyrethrum and E-β-farnesene are mentioned in table 1. (It is also possible to prepare other compositions than water-based compositions, e.g. methanol-based compositions). Furthermore the compositions contain a butane/propane mixture as the propellent gas, piperonyl butoxide (an insecticidal synergistic agent), the pyrethrum:piperonyl butoxide ratio being 1:5, and an emulsifier (nonylphenol having an average of 8-9 ethylene oxide units). 
     
                                           TABLE 1                                 
__________________________________________________________________________
Pyrethrum- and farnesene concentrations in aerosol cans.                  
Composition                                                               
         Concentrations, %*                                               
__________________________________________________________________________
pyrethrum (25%)    0.12 0.06 0.03 0.015                                   
pyrethrum (25%)/                                                          
         0.48/0.10                                                        
              0.24/0.10                                                   
                   0.12/0.10                                              
                        0.06/0.10                                         
                             0.03/0.10                                    
                                  0.015/0.10                              
farnesene                                                                 
farnesene                                                                 
         0.10                                                             
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 *The real concentrations of pyrethrum are in all cases lower by a factor 
 of 4 because in all cases 25% pyrethrum standard solutions were initially
 used.                                                                    
 
    
     The following aphids were used for the tests: 
     the pea aphid, Acyrthosiphon pisum 
     the green peach aphid, Myzus persicae (strains M 1 , M 2  and &#34;IPO-resistant&#34;, M 2  is a highly organic phosphate-resistant strain and &#34;IPO-resistant&#34; is a strain which is generally resistant to organic phosphates, carbamates and pyrethroids; (&#34;IPO&#34; means &#34;Instituut voor Plantenziektenkundig Onderzoek&#34;) 
     the bean aphid, Aphis fabae 
     the potato aphid, Macrosiphon euphorbiae 
     a species living on ferns, Idiopterus nephrolepidis 
     The mortality was determined 2 hours and 24 hours after treatment of the aphids. When permanently motionless the aphid was considered dead. This was concluded from the reaction of the aphids when touched with a brush, observed with a microscope. During the tests two petri-dishes with 20 aphids on filter paper, which were not sprayed, were placed in the experimental room in order to investigate the influence of external factors on the mortality. 
     Example 1 
     Tests with aphids on filter paper. 
     10 Petri-dishes per test were used; 5 for spraying with pyrethrum and 5 for spraying with the combination pyrethrum/farnesene. The petri-dishes had a diameter of 110 mm; the edge was coated with fluon (a dispersion of polytetra fluoro ethylene, ICI) in order to prevent the aphids from running away. On the bottom of each dish a filter paper having a diameter of 110 mm (Schut type V 255) was present. Into each petri-dish 20 aphids were brought (from larvae of the third stage to matured). 
     In one series of tests the aphids were directly sprayed. This was carried out vertically at a distance of about 30 cm. The spray times were in all cases the same (about 6 seconds). After 2 and 24 hours the percentage of mortality was determined by counting the number of dead and living aphids. 
     Also tests employing in direct spraying were carried out, the filter paper being sprayed first and thereafter the aphids were brought into the petri-dishes. 
     The results of these tests are summerized in tables 2 and 3. 
     
                       TABLE 2                                                     
______________________________________                                    
Results of direct spraying of aphids on filter paper (vide also           
footnote table 1)                                                         
                       % Mortality                                        
                                     after                                
                             after 2 24                                   
Species      Compositions    hours   hours                                
______________________________________                                    
A.   Ac. Pisum   0.015% pyr.     30%   100%                               
                 0.015% pyr./0.1% farn.                                   
                                 100%  100%                               
B.   Ac. Pisum   Dist. H.sub.2 O  0%    0%                                
                 0.00% pyr./0.1% farn.                                    
                                 30%    72%                               
*C.  Ac. Pisum   blank           10%   27.5%                              
                 0.00% pyr./0.1% farn.                                    
                                 25%    53%                               
D.   Myzus persicae                                                       
                 0.03% pyr.      30%   100%                               
     (IPO-resistant)                                                      
                 0.03% pyr./0.1% farn.                                    
                                 70%   100%                               
According to the CHI-square test the differences found in tests A,        
B, C and D are significant.                                               
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 *In test C &#34;blank&#34; means water + emulsifier.                             
 
    
     
                       TABLE 3                                                     
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Results of indirect spraying of aphids on filter paper (vide also         
footnote 25 table 1)                                                      
                  % Mortality                                             
                                   after                                  
Species Composition     after 2 hours                                     
                                   24 hours                               
______________________________________                                    
Ac. Pisum                                                                 
        0.015% pyr.     20%        100%                                   
        0.015% pyr./0.1% farn.                                            
                        40%        100%                                   
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     From the above results the following appears: 
     (1) The combination aphid insecticide/pheromone has even a better activity than the insecticide alone (faster killing). 
     (2) The use of only the pheromone also results in a certain percentage of dead aphids. 
     Example 2 
     Tests with aphids on leaves and plants 
     A leave (vide table 4 for the plant species) having a known number of aphids (all stages of development) was put into the petri-dish. The aphids were sprayed as described for the direct spraying of aphids on filter paper. After the treatment the number of living and dead aphids were again determined after 2 and 24 hours and converted to percentages. 
     Furthermore different plant species (vide table 5) having aphids were sprayed from 4 sides at a distance of about 30 cm. Plants having a leave surface of 300-500 cm 2  and an estimated aphid population of 150 aphids per 100 cm 2  were selected. Under the plant black card board was placed in order to observe the falling aphids. Thereafter leaves were cut from the plants and stored in petri-dishes having a fluon edge, in order to determine the mortality. Also tests were carried out wherein the aphid mortality on the whole plant was determined. 
     
                                           TABLE 4                                 
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Results of spraying aphids on leaves (vide also footnote table 1)         
                                     Mortality                            
Aphid species   Plant species                                             
                         Composition 2 hours                              
                                         24 hours                         
                                              Remark                      
__________________________________________________________________________
A. Myzus persicae M.sub.1                                                 
                Chinese cabbage                                           
                         0.12% pyr.   50%                                 
                                         100% 200 aphids per leave of 50  
                                              cm.sup.2                    
   Myzus persicae M.sub.1                                                 
                Chinese cabbage                                           
                         0.12% pyr./0.1% farn.                            
                                      80%                                 
                                         100% 200 aphids per leave of 50  
                                              cm.sup.2                    
B. Myzus persicae M.sub.2                                                 
                Cole seed                                                 
                         blank       n.d.                                 
                                          28% 210 aphids per leave of 70  
                                              cm.sup.2                    
   Myzus persicae M.sub.2                                                 
                Cole seed                                                 
                         0.00% pyr./0.1% farn.                            
                                     n.d.                                 
                                          82% 170 aphids per leave of 70  
                                              cm.sup.2                    
C. Myzus persicae M.sub.1 + M.sub.2                                       
                Cole seed                                                 
                         0.06% pyr.   40 100% 120 aphids per leave of 60  
                                              cm.sup.2                    
   Myzus persicae M.sub.1 + M.sub.2                                       
                Cole seed                                                 
                         0.06% pyr./0.1% farn.                            
                                      60%                                 
                                         100% 160 aphids per leave of 60  
                                              cm.sup.2                    
D. Ac. Pisum    Broad beans                                               
                         0.06% pyr.   85.sup.2                            
                                         100% 5 × 20 aphids per     
                                              leave                       
   Ac. Pisum    Broad beans                                               
                         0.06% pyr./0.1% farn.                            
                                     100.sup.2                            
                                         100% 5 × 20 aphids per     
                                              leave                       
E. Macr. Euphorbiae                                                       
                Hibiscus sp.                                              
                         0.015% pyr./0.1% farn.                           
                                     n.d.                                 
                                         100% On the topleaves and the    
                                              blossoms                    
                                              a large population of       
                                              aphids, about               
                                              20-30 per leave             
F. Macr. Euphorbiae                                                       
                Hibiscus sp.                                              
                         blank        0%  0%.sup.1                        
                                              On the topleaves and the    
                                              blossoms                    
                                              a large population af       
                                              aphids, about               
                                              20-30 per                   
__________________________________________________________________________
                                              leave                       
 .sup.1 no visible mortality observed.                                    
 .sup.2 determined after 1 hour                                           
 n.d. = not determined.                                                   
 
    
     
                                           TABLE 5                                 
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Results of spraying aphids on plants (vide also footnote 1)               
                             Mortality                                    
Aphid Species                                                             
          Plant species                                                   
                 Composition 2 hours                                      
                                 24 hours                                 
                                      Remark                              
__________________________________________________________________________
A.                                                                        
  Myzus persicae                                                          
          Cole seed                                                       
                 0.015% pyr. 30%  90% aphids fall from the plant          
  (IPO-resistant)                                                         
                 0.015% pyr./0.1% farn.                                   
                             70% 100%                                     
B.                                                                        
  Idiopterus                                                              
          Fern   0.12% pyr.  50% 100% no falling aphids observed          
  Nephrolepidis  0.12% pyr./0.1% farn.                                    
                             75% 100% great number of aphids fall         
                                      from the plant                      
C.                                                                        
  Aphis fabae                                                             
          Broad bean                                                      
                 0.12% pyr.  70% 100% aphids fall sporadically            
                 0.12% pyr./0.1% farn.                                    
                             80% 100% aphids fall sporadically            
                                      but run away                        
D.                                                                        
  Myzus persicae                                                          
          Radish 0.015% pyr. 40%  90% 5 plants having 5 leaves per test   
  (IPO-resistant)                                                         
                 0.015% pyr./0.1% farn.                                   
                             70% 100% and about 500 aphids per leave      
                                      aphids fall from the                
__________________________________________________________________________
                                      plant                               
 n.d. not determined.                                                     
 
    
     
                       TABLE 6                                                     
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Results from spraying aphids on plants (vide footnote table 1).           
Per test: 5 plants (broad beans) having 20 aphids (A. pisum) per          
plant. Spraying time about 6 seconds.                                     
Composition      Mortality after 19 hours                                 
______________________________________                                    
0.004% pyrethum (25%)                                                     
                 17 dead aphids                                           
                 12 dead aphids                                           
                 13 dead aphids                                           
                 14 dead aphids                                           
                 15 dead aphids                                           
                 Average 71%, varies between                              
                 60 and 85%                                               
0.004% pyrethum (25%),                                                    
                 17 dead aphids                                           
0.1% E-β-farnesene                                                   
                 17 dead aphids                                           
                 20 dead aphids                                           
                 18 dead aphids                                           
                 19 dead aphids                                           
                 Average 91%, varies between                              
                 90 and 100%                                              
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     When spraying plants, no damage to the plants was observed for any of the compositions; there was some damage to the fern (table 5), but in this case recovery occured later. 
     Also from tables 4, 5 and 6 it appears that the combination aphid insecticide/pheromone gives a faster killing than only the insecticide and that the use of only the pheromone also results in a certain percentage of dead aphids. Furthermore the combination aphid insecticide/farnesene appears to have a superior activity for resistant aphids (table 4). 
     From table 5 it appears that by using farnesene the aphids fall from the plant.