الفهرس 
I. INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 314 |  |  |
| | | from | 314 | | |
Abstract
The present study was carried out to evaluate the comparative efficiency of six insecticides and parasitoid, M. rufeventris against the cotton leafworm, S. littoralis. This study evaluated the biological, biochemical and
genetical effects of plant based insecticide (Neem-Force ),
insect growth regulator (Lufenuron), organophosphate
(Chloropyrifos), bioinsectcide (Emamectine Benzoate ) and
insecticide mixtures (Chlorosan and Mach-Fit) against 4th instar
larvae.
According to LC50 and LC90 values, Mach-Fit was the
most effective control agent followed by Lufenuron, Emamectin
Benzoate, Chloropyrifos, Chlorosan and Neem-Force.
A-Biological effects:
1- Impact of Lufenuron on some biological aspects of the 4th
instar larvae.
-Lufenuron at different concentrations caused significant
prolongation in the larval and pupal duration and this
prolongation was concentration-dependant.
-Generally, mortality percentage of treated larvae significantly
increased and this increase was concentration-dependant.
239
-Our results, clearly indicated that there was an inverse
relationship between the different concentrations of Lufenuron
and the pupation percentage of treated larvae.
-All of the tested concentrations induced significant decrease in
the pupal weight, as it was 0.211gmat concentration of 0.046
ppm compared with 0.254 ppm in control group.
-The percentage of adult emergence of treated larvae
significantly decreased with an increase in the applied
concentrations, as well as, sex ratio was shifted towards male
side compared with control.
-Lufenuron caused significant decrease in the fecundity and
fertility of adults treated as larvae, as well as, adult longevity of
both sexes of the emerged adults significantly decreased as
compared with control.
2- Impact of Mach-Fit on some biological aspects of the 4th
instar larvae.
- All the applied concentrations of Mach-Fit caused significant
prolongation in the larval and pupal duration of treated larvae
compared with control. For example, larval prolongation ranged
between 9.22 and 10.06 days and 8.2 and 7.8 days for pupal
duration respectively at concentration of 0.01 and 0.001pm.
-The percentage of larval mortality significantly increased, as it
was27.5, 43.0, 72.4 and 74.1% at the concentration 0.001,
240
0.002, 0.005 and 0.01ppm respectively compared with 3.4 % in
control.
- Significant decrease was recorded in the pupation percentage
of treated larvae. Decreased pupal weight was also recorded,
and this decrease was 0.171and 0.154 gm at concentration of
0.001and 0.01 ppm, respectively compared with 0.182 gm in
control.
-Adult emergence of treated larvae was 74.8 and 88.8%with
concentration0.001 and 0.01ppm compared with 98.4% for
control, as well as, adult sex ratio was shifted towards male side
-The fecundity and fertility of adults treated as larvae
significantly decreased compared with control.
-Adult longevity of treated 4th instar larvae (male and female)
significantly decreased as it was 9.01 and 8.97 days for males
and 9.02 and 8.32 days for females, respectively at
concentration 0.005 and 0.01 ppm compared with 9.22 days for
males and 9.43 for females in control.
3- Impact of Chlorosan on some biological aspects of the 4th
instar larvae.
-A significant prolongation was found for larval and pupal
duration of the treated larvae compared with control with a
concentration-dependant manner.
241
-There was an inverse relationship between the concentrations
of Chlorosan and the larval mortality, pupal weight and pupation
percentage of treated larvae.
-The adult emergence percentage significantly decreased with
an increase in the concentrations of Chlorosan, recording 77.3%
at concentration 0.8 ppm compared with 100% for control, with
the adult sex ratio shifted towards male side.
-Pupal and adult malformation was reported with higher
treatments of 4th instar larvae with Chlorosan
-The decrease in fecundity ranged between 2777.3 and 3897.6 eggs/2 female at concentration 0.8 and 0.1 ppm, respectively
compared to 4252.3 eggs/2 female in control group, as well as,
the fertility of emerged adults significantly decreased in a
concentration-dependant manner.
4- Impact of Emamectin Benzoate on some biological aspects
of the 4th instar larvae.
-Significant prolongation in the duration of treated larvae was
observed at concentration 0.07, 0.15 and 0.3 ppm, where it was
8.59, 8.72 and 8.77 days, respectively compared with 7.74 days
in control group. As well as, pupal duration significantly
decreased with Emamectin Benzoate treatments.
- The larval mortality percentage of treated larvae significantly
decreased with the increase of concentration. Hence, the
pupation percentage of treated larvae significantly decreased.
242
-The pupation percentages of treated larvae was 78.4, 61.7, 53.4
and 38.4% at concentration 0.03, 0.07, 0.15 and 0.3 ppm,
respectively compared with 96.7 % in control group.
-The highest decrease in the pupal weight was 0.191gm at
concentration 0.3 ppm, compared with 0.222 gm for control.
-There was a significant decrease in adult emergence percentage
as it was 90.2, 87.4, 79.9 and 77.5% respectively, at
concentration 0.03, 0.07, 0.15 and 0.3 ppm. Also the adult sex
ratio was shifted to males at all tested concentrations compared
with control.
-The results reported malformations with concentration 0.15 and
0.3 ppm, as the malformations percentage recorded respectively
4.3 and 5.2 % for pupa and 1.0 and 1.2 % for adults compared
with 0.0 % for control.
-The fecundity and fertility showed a significant decrease in a
concentration-dependant manner. Also, significant decrease in
the adult longevity was observed at higher concentrations (0.15
and 0.3 ppm) of Emamectin Benzoate.
5- Impact of Neem-Force on some biological aspects of the
4th instar larvae.
-Neem-Force elicited significant prolongation in both larval and
pupal duration compared with control group. As well as, the
larval mortality percentage significantly increased with an
increase in the applied concentration of Neem-Force.
243
-Pupation percentage and pupal weight significantly decreased
compared with control, as for example pupation percentage was
88.4, 68.3, 50.0 and 35.0% at concentration 5, 10, 20 and 40
ppm, respectively compared with 98.3% in control.
-The emergence of adults treated as larvae significantly
decreased by Neem-Force treatments as well as, adult sex ratio
shifted towards male at all tested concentrations except 40 ppm,
it was shifted to the female side.
- Significant decrease in fecundity and fertility of emerged
adults was observed at all tested concentration and this decrease
was concentration-dependant.
6- Impact of Chloropyrifos on some biological aspects of the
4th instar larvae.
-Insecticide treatments reported a significant prolongation of the
larval and pupal duration. As well as, the percentage of larval
mortality significantly increased with an increase in the tested
concentration of Chloropyrifos.
-Significant decrease in the pupation percentage and pupal
weight was found at all tested concentrations, as for example
pupation was 66.7% at concentration 0.64 ppm compared with
98.3% for control.
-A significant decrease was reported in the percentage of adult
emergence, as it was 88.88, 79.9 and 77.89% at concentration
0.16, 0.32 and 0.64 ppm compared with 100.0% for control.
244
-The sex ratio of adults treated as larvae was shifted to males at
all tested concentrations compared with control.
-All tested concentrations of Chloropyrifos caused significant
decrease in adult fecundity, as well as, the fertility and longevity
of emerged adults significantly decreased.
-Treatments of 4th instar larvae of S. littoralis elicited
morphological aberrations including the appearance of larvalpupal
intermediates and malformed pupae appeared as rod like
C-shaped, elongated or fused C shaped pupae.
-Abnormalities of emerged adults appeared as incomplete
eclosion of adults and adults with either malformed antennae,
wings or legs.
B- Effect of parasitoid M. rufeventris on some biological
aspects of the 2nd , 3rd, 4th and 5th instar larvae
Our results clearly indicated that, 2nd instar larvae was the most
affected one followed by 3rd and 4th instar. Furthermore, 5th
instar larvae not significantly affected compared with control
group. The results revealed that, larval and pupal duration, pupal
weight; and longevity, fecundity and fertility of emerged adults
were significantly not affected at all larval stages treated with
parasitoid compared with control group, as all parasitized larvae
died and only non parasitized larvae complete normal
development.
245
C- Biochemical effects of tested insecticides on 4th instar
larvae.
Results showed that treatment with Lufenuron, Mach-Fit ,
Emamectin benzoate, Chloropyrifos, Chlorosan and Neem-
Force significantly affected the biochemical aspects of S.
littoralis larvae. Homogenate of 4th instar larvae treated for 48
hrs with above insecticides showed significant disturbance
intotal carbohydrate, protein and lipids content and as well as,
the activity of GOT, GPT, amylase, invertase, trehalase and α
and β specific esterases significantly altered. Statistical analysis
indicated that all the above biochemical parameters significantly
decreased at all tested insecticides except activity of invertase
enzyme increased by Chlorosan and Chloropyrifos, GPT and β
esterase enzymes significantly increased by Neem–Force and
GPT enzyme activity significantly increased by Emamectin
Benzoate and Chloropyrifos compared with control.
D- Genetical effects of tested insecticides on 4th instar larvae.
The results revealed that all the above tested
insecticides at different concentrations significantly affected
the electrophoretic DNA and RNA of cuticle and midgut of
treated 4th instar larvae and of adult ovary of treated larvae.
Larval treatments significantly decreased the density of
electrophoretic DNA and RNA and this decrease was
concentration-dependant. On the other hand, DNA
246
fragmentation significantly increased by all tested insecticides
and the Lufenuron insecticide was the most effective one
followed by Mach-Fit, Emamectin Benzoate, Chloropyrifos and
Chlorosan. On the other hand, the Neem-Force insecticide was
the lowest effective one. As well as, the results revealed that
there was a direct correlation between RNA optical density and
the elctrophoretic Protein pattern of cuticle and midgut of
treated 4th instar larvae and of adult female ovary treated as
larvae.