الفهرس 
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Abstract
-1. Four different species of food plants, garlic (Allium
sativum); Parsley (Petroselinum crispum) ; onion
(Allium cepa), and coriander ( Coriandrum sativum),
pertaining to different families were screened for
their toxicity and/or their synergistic activity
against mosquito larvae, Culex pipiens pipiens L ••
They were selected on the basis of their probable
toxicity to insects and/or their pharmacological ,
toxicological or physicological effects which they,
or their related species may have on other animals.
2. In assessing their toxicity the plants or plant parts
were extracted at the rate nf 30 g/100 ml acetone.
Acetone extracts were screened for their toxicity
against mosquito larvae. Results analysed according
to the method of Litchfield and Wilcoxon (1949). LCso
values were 7.0, 20.0, 40.0 and 70.0 ppm for the
acetone extracts of ~ sativum, P. crispum, ~ cepa
and C. sat i vum ?rre~ectively. These results revealed
that garlic and parsley extracts showed promising
insecticidal effect against mosquito larvae.
3. The volatile oils of the most promising plants,,
’ garlic and parsley,. were isolated by steam distillation
and their percentages were 0.568 and 0.06 % ,
respectively.
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4. Volatile oils of garlic and parsley were screened
for their toxicity and/or synergistic activity to
the public health inse~t, C. pipiens pipiens L.
larvae. LCso values of the tested volatile oils
were as follows; garlic oil = 2.5 ppm and parsley
oil = 20.0 ppm. LCso of garlic oil was consistently
lower than the corresponding whole plant extract •
These results indicate that the active principle
responsible for the toxicity of garlic may be present
in its volatile oil. Three synthetic pyrethroids,
esbiol, neopynamin, and sumithrin were screened
for their toxicity against the mosquito larvae.
Esbiol proved to be the most toxic with LCso value
of 0.39 ppm followed by neopynamin and sumithrin
with LCso values of 1.2 and 1.3 ppm, respectively.
Results of synergism studies revealed that parsley
oil synergized two insecticides, esbiol and ·
sumithrin, while garlic oil synergized esbiol only.
These preliminary investigations regarding the
toxicity and synergistic activity of the active
principle of garlic, garlic oil, to Culex larvae revealed
a potential source of a potent mosquito larvicide
for mosquito control and a potent synergist
for pyrethroid against the same insect •
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S. Garlic and parsley oils were screened for their toxicity
and/or synergistic activity to the susceptible
and resistant adults of the red flour beetle, T.
castaneum (Herbst). Against the adults of the susceptible
strain, garlic oil was more toxic (Lc50 = 20
ug/cm~) than parsley oil (LC
50 ~ 72 ug/cm~). However,
the adults of the field strain were found to be less
sensitive to the toxic effect of the tested oils than
that of susceptible strain, since the LC
50
values were
32 and 85 ug/cm 2 for garlic oil and parsley oil, respectively.
Again garlic oil was more toxic to the red
flour beetles than parsley oil.
On the other hand, the adults of malathion- and
methomyl-resistant strains were found to be more susceptible
to the tested oils. Their Lc
50
values were
9.4 ug/cm 2 and 12.7 ug/cm2
• Three commercial insecticides,
malathion, methomyl, and permethrin, were
screened for their toxicity to the adults of the field
strain of I· castaneum. The insecticidal potencies of
these insecticides as represented by their LC50 values
were: 0.56, 0.31 and 0.29 ug/cm 2 for malathion, permethrin
and methomyl, respectively. The toxic effect of
these insecticides surpassed the insecticidal effect of
garlic oil. Results of synergism studies revealed that
the two oils synergized only the pyrethroid insecticide,
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permethrin, and antagonized the toxicity of the organophosphorus
insecticide, malathion, and the carbamate compound,
methomyl. These findings suggest that garlic and
parsley oils might be used to overcome the resistance of
this insect pest of stored products to certain extent.
Also, on the basis of the values of the co-toxicity factor,
garlic oil was found to be more potent as a synergist than
parsley oil.
In conclusion, results of the present work suggest
the possibility of using the active principle of garlic,
garlic oil, for control both mosquito larvae f. pipiens
pipiens L. and the more insecticide-resistant populations
of the red flour beetle, T. castaneum (Herbst). Also, it
can be stated that garlic and parsley could be promising
sources of naturally occurring synergists for pyrethroids
in both insects.