الفهرس 
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Abstract
Effects of Irradiation on the Susceptibility of
the Cotton Leaf Worm, Spodoptera littoralis
(Boisd.) to Anticholinesterase Insecticides
The present study aimed at the evaluation of the effect
of Y-ray on the susceptibility of the cotton leaf worm, to
anticholinesterase insecticide, through investigating the
following points with the outlined results :-
1- The effect of irradiation of S. littoralis pupae on
the susceptibility of emerging adults and their F1 fifth
instar larvae to three anti-ChE insecticides.
2- Quantitative and qualitative analysis of ChE activity
in adults emerging from irradiated pupae and their F1 larvae.
3- The relation between ChE inhibition and the anticipated
changed susceptibility of the irradiated insects to methomyl,
pyridaphenthion and fenitrothion.
1- Susceptibility of adult and F1 larval progeny irradiated
as Pupae to insecticides
1- Methomyl was the most potent insecticide, followed by
pyridaphenthion while fenitrothion was the least potent
against both normal, irradiated larvae and adults.
2- Normal adult d’ and ~ were more sensitive to the three
insecticides than larvae.- 87 -
3- Irradiation increased the susceptibility of larvae and
adults
Gt~
irradiated pupae to the three insec/
ticides.
4- Adult &! and ~~ produced from irradiated pupae were
more sensitive to insecticides than F1 larval progeny.
5- Irradiated female showed higher rates of increase in
their susceptibilities to insecticide than rcr.
le> YV’i!.
6-
1
F 1 ( r’?. Nd’) showed the highest increase in susceptibility
relative to normal larvae against all tested insecticides.
This was followed by larvae of F1 (I’?.rt) and F1 (Icf.
NS) respectively.
2- ChE activity in normal larvae and adults :
ChE activity was detected in larvae and adult ~and~-
The values of the activity were 12.4±0.18, 8.8±0.71 and
22.2±0.54 VM Ach hydrolyzed/60 min/gm tissue respectively.
3- ChE activity in adult and F1 larval progeny produced from
irradiated pupae :
Irradiation influenced ChE activity and its effect
1;,
varied according the stage and sex of the insect.
I
4- ChE activity in adult and larvae as influenced by insecticides
:
1- There was an inhibitory action of the three insecticides
on ChE activity in larvae and adults. This was pronounced
in vivo and in vitro determinations.- 88 -
2- There is no correlation between in vivo and in vitro
determinations of ChE inhibition and toxicity of the evaluated
insecticjdes.
5- Combined effect of x-ray and insecticides on ChE activity:
The activity of irradiated ChE in response to the three
insecticides varied greatly from inhibition, no effect to
activation.
6- Substrate cone,., •-ton and specificity of ChE of x-ray
or fenitrothion treated of ~ littoralis :
1- ChE hydrolyzed Ach, AMech and Bzch at different rates
depending on their chemical nature, concentration,and insect
stage.
2- ChE of all stages hydrolyzed Bzch at higher rates than
Ach and AMech.
3- Abell-shaped curve typical of ChE specific for Ach,
was not obtained.
4- ChE of larvae and adultsis mostly a non specific type,
with an interference of low activity of a specific type.
5- Fenitrothion inhibited ChE at almost all concentrations
in all stages. However, it increased ChE activity at certain
substrate concentrations in the female.
6- The effect of irradiation on ChE activity varied between
no effect, activation or inhibition according to the
chemical nature
stages and sex.
7
concentration of substrate J insect- 89 -
7- Fenitrothion or y-ray did not seem to alter the type
of the enzyme. In both treatments the enzyme affinity towards
hydrolyzing different substrates was basically the
same as normal enzyme.