Neem oil fatty acid distillation residue based pesticide

Neem oil fatty acid distillation residue based pesticide which is storage stable, water soluble, environmentally safe and rich in bitter principles. It is obtained by saponifying the neem oil fatty acid distillation residue with an aqueous alkali, drying the resulting soap, allowing the resulting soap cake to cool down to room temperature, pulverising the soap cake, fortifying the resulting fines by mixing with a small quantity of neem oil, allowing the fines to dry at room temperature and if desired, forming an aqueous emulsion by mixing the pesticidal fines with water at room temperature. The fines may be enriched by mixing with a small quantity of a solvent extract of neem tree parts prior to allowing the fines to dry.

This invention relates to neem oil fatty acid distillation residue based 
pesticide and a process for the preparation thereof. 
Pesticides of plant origin are in general preferable to the synthetic ones 
because of their relatively shorter persistance in the atmosphere, easier 
biodegradability and lower toxicity to human beings and other flora and 
fauna. 
Neem oil from neem tree (Azadirachta indica) is known to possess pesticidal 
activity. Direct spraying of neem oil on plants is likely to result in 
deposition of high concentration of oil on the foliage of plants. This 
will be toxic and harmful to the foliage of plants, besides being 
uneconomical. Therefore, from the economic and toxicity points of view, 
neem oil has to be mixed with water to spray on foliage and plants, but 
aqueous emulsion of neem oil is not known to have been used on a 
commercial scale as a pesticide due to factors such as cost of high 
concentration of neem oil required in the emulsion for effective pest 
control, unstable nature of the aqueous emulsion over long periods of time 
and phutotoxic symptoms on the foliage and plants. 
The limonoid bitter principles (lipid associates) such as azadirachtin, 
salanin, meliantriol, deacetylsalanin and nimbidin contained in the neem 
oil are reported to be responsible for the pesticidal activity of neem 
oil. (Vimal, O.P. and Naphade, K.T. 1980, Jour. Sci. Ind. Res. Vol. 39, p. 
197-211). 
U.S. Pat. No. 4,556,562 (1985) of Robert O Larson describes a process for 
the preparation of a storage stable aqueous emulsion of neem seed extract 
consisting of forming neem seed particles, extracting the particles with 
ethanol at 60.degree. C. to 90.degree. C. and separating the extract to 
obtain a solution of 40 to 45% by weight of neem oil containing 
azadirachtin and diluting the solution with water and non-ionic 
emulsifying agent to form an aqueous emulsion and if necessary adjusting 
the pH of the emulsion between 3.5 to 6.0 with ammonium hydroxide. 
Neem oil fatty acid distillation residue is a byproduct formed during 
fractional distillation of fatty acids obtained by hydrolysis (high 
pressure splitting) of neutral neem oil at 380 to 400 psi (pounds per 
square inch) pressure and 230.degree. to 240.degree. C. The neutral neem 
oil is obtained by distillative deacidification of industrial grade neem 
oil. Neem oil fatty acid distillation residue is a thick dark brown 
viscous liquid insoluble in water. Because of the thick viscous nature of 
the residue it also can not be normally formed into an aqueous emulsion 
thereof as such. It may be obvious to an oil technologist that an aqueous 
emulsion of the residue could however, be made by dissolving the residue 
in an organic solvent with an emulsifier and diluting the emulsifiable 
concentrate with water. An organic solvent based aqueous emulsion of the 
residue is not reported to have been neither made nor used as a pesticide. 
To the best of our knowledge, neem oil fatty acid distillation residue is 
of no or negligible commercial value and is disposed of as a waste 
material or used as fuel in furnaces. 
By extensive research and experiments we have found out a neem oil fatty 
acid distillation residue based pesticide which is storage stable, water 
soluble, environmentally safe and rich in bitter principles. 
An object of the present invention is to provide a neem oil fatty acid 
distillation residue based pesticide which is storage stable, water 
soluble, environmentally safe and rich in bitter principles. 
Another object of the present invention is to provide a process for the 
preparation of the neem oil fatty acid distillation residue based 
pesticide. 
The process for the preparation of the neem oil fatty acid distillation 
residue based pesticide consists of: 
i) saponifying the neem oil fatty acid distillation residue with an aqueous 
alkali at 85.degree. to 140.degree. C. and atmospheric pressure, the 
concentration of the alkali in water being 10 to 50% by weight and the 
molar ratio of the residue and alkali being 1:1.05 to 1:1.2; 
ii) drying the resulting soap at 100.degree.-110.degree. C.; 
iii) allowing the resulting soap cake to cool down to room temperature; 
iv) pulverising the soap cake; 
v) fortifying the resulting fines by mixing with 5 to 10% by weight of neem 
oil; 
vi) allowing the fines to dry at room temperature and obtain the pesticide; 
and 
vii) if desired forming an aqueous emulsion of the pesticide by mixing the 
pesticidal fines with water at room temperature in the ratio 0.5:100 to 
3:100. 
The alkali used for saponification of step (i) is, for example, sodium or 
potassium hydroxide, sodium hydroxide being the preferred alkali as it 
results in harder soap which can be converted into fines easily. 
A concentrated alkali solution containing 45 to 50% by weight of the sodium 
hydroxide is preferred for the saponification of step (i) as the resulting 
soap will have reduced water content and can be dried faster. 
A dilute aqueous alkali solution containing as low as 2% by weight of 
alkali concentration could also be used for saponification of step (i) but 
the resultant soap would contain a lot of moisture and require additional 
energy for drying. A dilute aqueous alkali (containing as low as 2% by 
weight of alkali concentration) saponification is also, however, within 
the scope of the present invention and its scope should be construed 
accordingly. 
The saponification of step (i) is preferably, carried out at 90.degree. C. 
The molar ratio of the residue and alkali for the saponification of step 
(i) is, preferably 1:1.1 to 1:1.2. 
The soap cake is pulverised as per step (iv) into fines of 1.0 to 1.4 mm, 
preferably 1.1 to 1.2 mm size particles. 
The fortification of the fines with neem oil as per step (v) has been found 
to prevent caking of the fines and increase the shelf life of the 
pesticide and also fortify the pesticide with the bitter principles some 
of which may have been lost or may have undergone chemical changes 
partially or fully during the high pressure splitting of the neutral neem 
oil. 
An emulsion of the pesticide as per step (vii) is formed by mixing the 
pesticide fines with water at room temperature in the ratio 0.5:100 to 
3:100 (w/w) at the time of spraying of the pesticide on the foliage of 
plants. A concentration of 0.5% to 3.0% by weight of the pesticide was 
found to be quite effective as can be seem from the following tables. 
In order to enrich the fines obtained by step (v) with the bitter 
principles, the fines may be mixed with 5 to 10% of a solvent extract of 
neem tree parts such as seeds, leaves, or barks prior to allowing the 
fines to dry as per step (vi). The solvent extract is prepared in known 
manner using a solvent such as methanol, ethanol, acetone or petroleum 
ether. 
Preferably, the soap is dried as per step (ii) at 110.degree. C.

The following examples are illustrative of the present invention but not 
limitative of the scope thereof. 
EXAMPLE 1 
Neem oil fatty acid distillation residue (1 kg) was heated to 90.degree. C. 
in a sigma mixer at atmospheric pressure and a solution of sodium 
hydroxide (107 g; 2.6 moles) in water (100 milliliters) was added to it 
under stirring over one hour. The soap was dried in an electric oven at 
110.degree. C. for 4 hours. The soap cake was allowed to cool down to room 
temperature and contained a moisture content of 1%. The cake was 
pulverised in a hammer type pulveriser into fines of 1.1 to 1.2 mm. The 
fines (1.0 kg) were mixed with industrial grade neem oil (50 g) and 
allowed to dry at room temperature. The pesticidal fines were dark brown 
and completely free flowing. 
EXAMPLE 2 
The procedure of example 1 was followed and the fines mixed with neem oil 
were further mixed with methanol extract of neem seeds (50 milli liters) 
prior to drying at room temperature. The pesticidal fines were dark brown 
and completely free flowing. 
The methanol extract was prepared as follows: 
Neem seeds (50 g) containing 18% by weight of neem oil were crushed and 
soaked in methanol (50 ml) for 4 hours under stirring at room temperature. 
The seed particles were separated from the methanol extract and extracted 
twice again with fresh methanol (25 ml) for 15 minutes each time. The 
methanol extracts were pooled together. 
Using aqueous emulsions of the pesticide of examples 1 and 2, bioefficacy 
(pesticidal activity) studies were carried out and the results are shown 
in the following tables. The aqueous emulsions were prepared by mixing the 
pesticide of examples 1 and 2 in water at room temperature. 
The following tables 1 to 3 give test results in laboratory: 
TABLE 1 
__________________________________________________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide of 
example 1 on the food consumption by larvae of tobacco 
caterpillar (Spodoptera litura) 
% Feeding 
Larval stages Pupal 
Treatments IInd IIIrd 
IVth Vth Wt (mg) 
__________________________________________________________________________ 
Control (Water) 
5.7 .+-. 1.3 
7.1 .+-. 1.1 
12.5 .+-. 1.0 
13.1 .+-. 2.1 
379 .+-. .03 
Percentage of the pesticide 
of example 1 in the aqueous 
emulsion thereof 
(0.5%) 3.4 .+-. 0.7 
4.7 .+-. 0.5 
5.3 .+-. 0.8 
8.7 .+-. 1.9 
293 .+-. .03 
(1.0%) 3.4 .+-. 1.1 
4.0 .+-. 0.6 
4.6 .+-. 0.2 
8.2 .+-. 1.0 
262 .+-. .02 
(2.0%) 3.0 .+-. 0.9 
3.7 .+-. 0.5 
4.5 .+-. 0.9 
6.3 .+-. 0.6 
256 .+-. .02 
(3.0%) 2.1 .+-. 1.2 
3.0 .+-. 1.0 
4.0 .+-. 0.4 
6.0 .+-. 0.5 
234 .+-. .01 
__________________________________________________________________________ 
##STR1## 
TABLE 2 
__________________________________________________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide of 
example 1 on pod borer/fruit borer (Heliothis armigera) 
Treatments % Mortality* 
Stages Larva Pre pupa Pupa 
Days after hatching.fwdarw. 
9 10 13 14 16 17 25 
__________________________________________________________________________ 
Control (Water) 
(0.5%) 
12.8 
28.5 
28.5 
21.5 
72.4 
72.4 
100.00 
Percentage of the pesticide 
(1.0%) 
42.0 
71.0 
100.0 
100.0 
100.0 
100.0 
100.0 
of example 1 in the aqueous 
emulsion thereof 
__________________________________________________________________________ 
##STR2## 
TABLE 3 
__________________________________________________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide of 
example 1 on spotted boll worm (Earias vitella) 
No of days Pupal 
larva alive 
Days taken 
Duration 
Pupal 
Treatments after treatment 
for pupation 
(days) 
Wt (g) 
__________________________________________________________________________ 
Control (Water) 
6.7 .+-. 0.27 
5.7 .+-. 0.28 
7.8 .+-. 0.21 
0.055 .+-. 0.00 
Percentage of the 
pesticide of example 1 
in the aqueous 
emulsion thereof 
(0.5%) 3.9 .+-. 0.25 
5.0 .+-. 0.10 
10.0 .+-. 0.00 
0.045 .+-. 0.01 
(1.0%) 3.9 .+-. 0.29 
6.3 .+-. 0.10 
12.0 .+-. 0.19 
0.042 .+-. 0.01 
(2.0%) 3.8 .+-. 0.18 
6.5 .+-. 0.08 
12.0 .+-. 0.00 
0.040 .+-. 0.01 
(3.0%) 3.2 .+-. 0.12 
8.0 .+-. 0.00 
No adult 
0.030 .+-. 0.00 
emergence 
__________________________________________________________________________ 
Each value is the mean of 20 replicates .+-. standard error of means. 
The following tables 4 to 10 give test results obtained under field 
conditions 
TABLE 4 
______________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide 
of example 1 on the incidence of Aphids (Aphis gossypii) on 
Cotton at Phaltan, District Satara, Maharashtra, India 
Number of sprays = 4, each at an interval of 15 days 
Concentration of the pesticide of example 1, 
1 Kg/acre in 200 liters of water (0.5%). 
Insect count* 
Critical 
Date of Water spray The pesticide 
Difference 
observation 
control of example 1 
(p = 0.05) 
______________________________________ 
17.6.88 40.6 41.6 n.s. 
(Precount) 
18.6.88 SECOND SPRAY 
19.6.88 31.3 21.3 7.527 
20.6.88 37.3 19.3 7.918 
23.6.88 42.6 21.6 10.261 
28.6.88 49.0 27.6 10.690 
03.7.88 55.3 32.6 10.925 
Average 43.1 24.48 
03.7.88 THIRD SPRAY 
04.7.88 40.3 23.0 10.177 
05.7.88 47.6 20.3 11.537 
08.7.88 55.3 30.3 11.928 
13.7.88 60.0 21.3 12.194 
18.7.88 64.0 27.3 13.610 
Average 53.4 24.44 
18.7.88 FOURTH SPRAY 
19.7.88 40.0 25.0 12.527 
20.7.88 42.3 20.0 12.411 
23.7.88 47.6 16.6 12.476 
28.7.88 52.3 21.3 13.190 
02.8.88 55.6 24.3 13.452 
Average 47.5 21.44 
______________________________________ 
*Number of aphids on 5 randomly selected plants in each plot 
TABLE 5 
______________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide of example 
1 on the incidence of Jassids (Amrasca biguttula) on Okra at 
Phaltan, District Satara, Maharashtra, India 
Number of sprays = 3, each at an interval of 15 days 
concentration of pesticides of example 1 
1 Kg/acre in 200 liters water (0.5%) 
Insect count* 
Critical 
Date of Water spray Pesticide of 
Difference 
observation 
control example 1 (p = 0.05) 
______________________________________ 
01.1.89 28.25 27.25 n.s. 
(Precount) 
FIRST SPRAY 
02.1.89 24.25 20.25 3.021 
03.1.89 30.25 15.25 3.628 
06.1.89 31.00 16.00 3.909 
11.1.89 34.25 17.00 4.611 
16.1.89 40.25 17.00 5.011 
Average 32.00 17.10 
SECOND SPRAY 
17.1.89 30.00 16.25 5.621 
18.1.89 32.00 16.25 6.711 
21.1.89 32.25 15.00 6.952 
26.1.89 37.25 15.00 7.811 
31.1.89 40.25 15.50 7.921 
Average 34.35 15.60 
THIRD SPRAY 
01.2.89 30.00 11.25 8.511 
02.2.89 32.25 11.00 8.942 
05.2.89 37.25 16.25 8.723 
10.2.89 40.50 12.00 9.162 
15.2.89 46.25 12.00 9.513 
Average 37.25 12.50 
______________________________________ 
*Number of Jassids on 5 randomly selected plants in each plot 
TABLE 6 
__________________________________________________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide of example 1 on 
Cotton boll damage 
and the yield of seed cotton at Phaltan, District Satara, Maharashtra, 
India 
Total number of sprays = 4, each at an interval of 15 days 
Concentration of the pesticide of example 1 kg/acre in 200 liters water 
(0.5%) 
% bud damage 
% boll damage due to 
due to Earias vitella 
Pectinophora gossypiella 
Seed Cotton 
Treatments (spotted boll worm) 
(Pink boll worm) 
yield Q/ha* 
__________________________________________________________________________ 
Water sprayed control 
40.8 32.6 7.62 
Aqueous emulsion of 
35.8 30.2 10.68 
the pesticide of 
example 1 
% change over control 
(-12.2) (-7.3) (+40.1) 
with the aqueous 
emulsion of the 
pesticide of example 1 
__________________________________________________________________________ 
*Q/ha = Quintals/Hectare 
No phytotoxic symptoms were recorded in any plot. 
TABLE 7 
______________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide of 
example 1 on the fruit damage and yield of Okra at Phaltan, 
District Satara, Maharashtra, lndia 
Total number of sprays = 3, each at an interval of 15 days 
Concentration of the pesticide of example 1 - 1 Kg/acre 
in 200 liters water (0.5%) 
% fruit damage 
due to Earias 
Green fruit yield 
Treatments Vitella (Quintals/Hectare) 
______________________________________ 
Water sprayed control 
47.38 21.20 
Aqueous emulsion of 
28.64 26.68 
the pesticide of 
example 1 
% change over control 
(-39.55) (+25.85) 
with the aqueous 
emulsion of the 
pesticide of example 1 
______________________________________ 
No phytotoxic symptoms were recorded in any plot. 
TABLE 8 
__________________________________________________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide of examples 1 and 2 
on the 
infestation of cabbage aphids (Bravicoryne brassicae) in cabbage 
at Phaltan, District Satara, Maharashtra, India 
Total number of sprays = 3, each at an interval of 15 days 
Concentration of the pesticide of examples 1 and 2, 1 kg/acre 200 liters 
water (0.5%) 
Aphid Count* 
Aqueous emulsion 
Aqueous emulsion 
Critical 
Date of Water sprayed 
of the pesticide 
of the pesticide 
Difference 
observation 
Control of example 1 
of example 2 
(p = 0.05) 
__________________________________________________________________________ 
11.1.90 Precount 
63.33 66.0 68.66 2.22 
12.1.90 First Spray 
13.1.90 59.66 34.33 30.33 2.46 
14.1.90 60.33 29.33 24.33 2.06 
17.1.90 62.66 32.33 20.66 1.93 
22.1.90 69.00 35.00 27.33 1.65 
27.1.90 74.33 40.66 28.66 1.29 
Average 65.19 34.33 26.26 
29.1.90 Second Spray 
30.1.90 66.66 20.33 17.33 1.21 
31.1.90 67.66 20.33 18.00 1.53 
03.2.90 74.33 18.33 14.66 1.37 
07.2.90 77.66 26.66 22.66 1.62 
Average 71.58 21.44 18.16 
7.2.90 Third Spray 
8.2.90 80.33 18.33 16.00 1.57 
9.2.90 85.66 17.00 15.33 1.28 
12.2.90 89.33 18.66 16.33 1.21 
17.2.90 92.33 22.33 20.33 1.11 
22.2.90 114.0 35.66 30.33 1.15 
Average 92.33 22.39 19.66 
__________________________________________________________________________ 
*Number of aphids counted on 5 randomly selected plants in each plot. 
TABLE 9 
__________________________________________________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide of examples 1 and 2 
on the 
infestation of Diamond back moth larvae (Plutella maculepennis) of 
Cabbage 
at Phaltan, District Satara, Maharashtra, India 
Total number of sprays = 3, each at an interval of 15 days 
Concentration of the pesticide of examples 1 and 2, 1 Kg/acre 
in 200 liters water (0.5%) 
Diamond-back moth larvae count* 
Aqueous emulsion 
Aqueous emulsion 
Critical 
Date of Water sprayed 
of the pesticide 
of the pesticide 
Difference 
observation 
Control of the example 1 
of example 2 
(p = 0.05) 
__________________________________________________________________________ 
28.1.90 Precount 
21.33 24.33 22.66 1.86 
29.1.90 Second spray 
30.1.90 24.00 15.00 15.66 1.92 
31.1.90 23.66 15.00 15.00 1.80 
3.2.90 32.66 16.33 16.33 2.86 
7.2.90 37.66 17.00 17.66 2.11 
Average 29.49 15.83 16.16 
7.2.90 Third spray 
8.2.90 40.00 14.33 11.00 2.06 
9.2.90 41.66 14.33 14.33 2.53 
12.2.90 47.00 18.00 14.66 2.76 
17.2.90 48.33 18.33 16.33 2.13 
22.2.90 53.66 20.33 17.00 2.06 
Average 46.16 17.04 14.66 
__________________________________________________________________________ 
*Numbers of Diamondback moth larvae counted on 5 randomly selected plants 
in each plot. 
TABLE 10 
______________________________________ 
Bioefficacy of the aqueous emulsion of the pesticide of 
example 1 vis-a-vis different neem extracts on the infestation 
of pod borer (Heliothis armigera) and yield of gram (cicer 
arietinum) at Banswara, Rajasthan, India 
Seed Yield 
Pod damage (Quintals/ 
Treatments % Hectare) 
______________________________________ 
Control (water spray) 
27.55 7.65 
Aqueous suspension of neem 
17.04 8.65 
seed extract 
(5% concentration in water) 
Aqueous suspension of neem 
15.86 8.30 
leaves extract 
(5% concentration in water) 
Aqueous suspension of neem 
14.94 9.42 
oil fatty acid distillation residue 
dissolved in benzene with 
polysorbate-80 (polyoxyethyle 
sorbitanmonooleate of HiCO 
Products Ltd., Bombay, India) 
(suspension concentration 
in water 5.0%) 
Aqueous suspension of the 
10.55 12.69 
pesticide of example 1 
(0.5% concentration in water) 
Critical Difference (p = 0.05) 
2.41 0.44 
% change over control with the 
-61.70 +65.88 
aqueous emulsion of the pesticide 
of example 1 
______________________________________ 
The tables 1 to 10 clearly establish the antifeedant, repellant and growth 
retardant activities of the pesticide of examples 1 and 2. The tables 5 
and 10 also clearly establish that the aphids and jassids which have 
sucking type of mouth parts are controlled by the pesticide of the present 
invention indicating the systemic action of the pesticide, that the 
pesticide is translocated in the plant systems. 
Neem products are reported to be very safe from the environmental point of 
view. There is very little persistence of neem products in soil, water and 
plants (Ahmad, S. and Grainge, M. 1986, Economic Botany, Vol. 40, p. 
201-209). Neem tree parts such as leaves, fruits, stem, bark or roots are 
also known to be used in ayurvedic medicines from ancient times. It is, 
therefore, logical to conclude that the pesticide of the present invention 
is environmentally safe and is non toxic to human beings and other flora 
and fauna. Toxicity studies were, however, carried out using the aqueous 
emulsion of the pesticide of examples 1 and 2 and the results are given 
hereinbelow: 
TABLE 11 
______________________________________ 
Acute Oral Toxicity in rats 
% Mortality 
observation 
Dose mg/kg up to 7 days 
______________________________________ 
1 Pelleted food 0 
without pesticide of 
example 2 (control) 
2 Pelleted food + 
0 
2500 mg pesticide 
of example 2 
3 Pelleted food + 
0 
5000 mg pesticide of 
example 2 
4 Pelleted food + 
0 
7500 mg pesticide of 
example 2 
5 Pelleted food + 
0 
10000 mg pesticide of 
example 2 
______________________________________ 
Animals appeared normal. Since there was no mortality, LD 50 value could 
not be determined. 
TABLE 12 
______________________________________ 
Acute dermal toxicity in rabbits 
% Mortality 
observation 
Dose mg/kg up to 7 days 
______________________________________ 
1 Application of only saline 
0 
on body (control) 
2 Application of 5000 mg pesticide 
0 
of example 2 moistened with saline 
3 Application of 7500 mg pesticide 
0 
of example 2 moistened with saline 
4 Application of 10000 mg pesticide 
0 
of example 2 moistened with saline 
5 Application of 15000 mg pesticide 
0 
of example 2 moistened with saline 
______________________________________ 
Animals appeared normal. Since there was no mortality, LD 50 values could 
not be determined. Visual post-mortem report on the animals did not give 
any significant observation regarding toxicity. 
TABLE 13 
______________________________________ 
Toxicity study on Talapia mossambica, 
a fresh water fish 
% Mortality at 
Dose (ppm) in water 
the end of 96 hours 
______________________________________ 
1 Water (control) 0 
No pesticide 
2 10 ppm concentration of 
0 
pesticide of example 2 
3 20 ppm concentration of 
20 
pesticide of example 2 
4 25 ppm concentration 
40 
pesticide of example 2 
5 30 ppm concentration 
80 
pesticide of example 2 
6 40 ppm concentration of 
100 
pesticide of example 2 
______________________________________ 
The LC 50 values calculated after 96 hours observation by graphical 
interpolation was found to be 27 ppm for the aqueous emulsion of the 
pesticide of example 2. 
Mucous membrane irritation study in rabbits using the aqueous emulsion of 
the pesticide of example 2 (0.5%) showed mild irritation to the vaginal 
mucous membrane when compared to control (water). 
The documented toxicity levels for pyrethrin, a pesticide of natural 
origin, are as follows: 
a) Acute oral LD 50 far rats: 584-900 mg/kg body weight 
b) Acute percutaneous (dermal) LD 50 for rabbits: 1500 mg/kg body weight. 
c) Pyrethrins are highly toxic to fish. 
A comparison of the toxicity levels of pyrethrin mentioned above with the 
data of toxicity studies on aqueous emulsion of the pesticide of example 2 
clearly shows that the aqueous emulsion of the pesticide of example 2 has 
negligible toxicity effects.