Insecticidal composition and method for combatting aphids

The invention provides insecticidal compositions for combatting aphids, which compositions contain an aphid insecticide in an amount lower than the minimum usual percentage for said insecticide in an aphicidal composition and an alarm pheromone for aphids. The compositions of the invention are less toxic because of the reduced insecticide content but they are not less effective than the insecticidal compositions which do not contain an alarm pheromone.

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-.beta.-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, "Ned. Entomol. Ver., Amsterdam", A potential 
application of aphid alarm pheromones" 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 ("knock down") 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-.beta.-farnesene and .alpha.-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-.beta.-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 
__________________________________________________________________________ 
*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.sub.1, M.sub.2 and 
"IPO-resistant", M.sub.2 is a highly organic phosphate-resistant strain 
and "IPO-resistant" is a strain which is generally resistant to organic 
phosphates, carbamates and pyrethroids; ("IPO" means "Instituut voor 
Plantenziektenkundig Onderzoek") 
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. 
______________________________________ 
*In test C "blank" means water + emulsifier. 
TABLE 3 
______________________________________ 
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% 
______________________________________ 
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.sup.2 and an estimated aphid population of 150 
aphids per 100 cm.sup.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 
__________________________________________________________________________ 
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 .times. 20 aphids per 
leave 
Ac. Pisum Broad beans 
0.06% pyr./0.1% farn. 
100.sup.2 
100% 5 .times. 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 
__________________________________________________________________________ 
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 
______________________________________ 
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-.beta.-farnesene 
17 dead aphids 
20 dead aphids 
18 dead aphids 
19 dead aphids 
Average 91%, varies between 
90 and 100% 
______________________________________ 
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.