الفهرس 
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Abstract
Laboratory experiments were undertaken to evaluate the toxicity of certain novel insecticides that have different mode of action, to assess the synergistic action of glyphosate on the activity of these insecticides on the 4th instar larvae of Culex pipiens, and to conduct the histological and ultrastructural studies on
the effect of glyphosate on the liver of adult albino rats under laboratory
conditions.
Results procured throughout this work can be summarized as follows:
I. Synergistic action of glyphosate on novel insecticides against Culex
pipiens L. under laboratory conditions
1- After 24-h exposure, sulfoxaflor + spinetoram and abamectin
showed the most toxic insecticides (LC50 was 0.084 and 0.088 ng/ml,
respectively), spinosad and emamectin benzoate were of moderate toxic
insecticides (LC50 was 0.10 and 0.16, respectively). Whereas, indoxacarb and
imidacloprid were the least potent insecticides (LC50 was 9.26 and 14.12 ng/ml,
respectively). After 48-h exposure, emamectin benzoate was the most powerful
insecticide (LC50 was 0.0036 ng/ml), while sulfoxaflor + spinetoram, abamectin,
and spinosad were the modest insecticides. Further, imidacloprid was still the
lowest toxic insecticide ((LC50 was 5.57 ng/ml). The same trend was observed
after 72-h exposure.
2- Glyphosate significantly synergized the selected insecticides
except spinosad and emamectin benzoate after 24-h exposure, meanwhile, after
48 and 72-h exposure, glyphosate significantly synergized most of the selected
insecticides except spinosad (LC50 was 0.052 and 0.01, while SR was 0.38 and
0.30 after 48 and 72-h exposure, respectively) and the most toxic insecticides
after 48-h were emamectin benzoate (LC50 = 0.00074 ng/ml, and SR was 4.86),
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Chapter 5 Summary and Conclusion
whereas glyphosate tremendously synergized indoxacarb after 72-h (LC50 =
0.013 ng/ml and SR was 10.77).
3- According to the slope values of the tested insecticides, Culex
pipiens showed relative high homogeneity response to imidacloprid and
indoxacarb insecticides (4.11 and 3.67) after 24-h exposure, and demonstrated
heterogeneity to sulfoxaflor + spinetoram (0.63). However, after 48-h exposure,
Culex pipiens displayed heterogeneity response to emamectin benzoate (0.54).
The same trend was recognized after 72-h exposure.
4- Based on the slope values of the synergistic action of glyphosate on
each insecticide, Culex pipiens revealed homogeneity restraint towards spinosad
and indoxacarb (4.12 and 4.09), meanwhile it demonstrated heterogeneity
response to sulfoxaflor + spinetoram (0.57). After 48-h exposure, slightly
changes occurred to the response and Culex pipiens evidenced heterogeneity
towards emamectin benzoate (0.53). The same tendency was perceived after 72-
h exposure.
5- The toxicity index of selected insecticides based on the LC50
values of insecticides alone after 24-h exposure were 100, 95.45, 84, 52.50,
0.91, and 0.60 for sulfoxaflor + spinetoram, abamectin, spinosad, emamectin
benzoate, indoxacarb, and imidacloprid, respectively, whereas after 48-h
exposure, the values were 18.96, 10.59, 18, 100, 0.33, and 0.07, respectively.
The same trend was completely evidence after 72-h exposure.
6- On the other side, the toxicity index of selected insecticides in
combination with glyphosate was 100, 78.26, 7.50, 6.79, 1.07, and 0.80 for
abamectin, sulfoxaflor + spinetoram, emamectin benzoate, spinosad,
imidacloprid, and indoxacarb, respectively. After 48-h exposure, the values
were 6.17, 12.13, 100, 1.42, 0.03, and 0.21, respectively. Similar direction was
observed after 72-h exposure.
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Chapter 5 Summary and Conclusion
7- According to the LT50 values, emamectin benzoate and abamectin
demonstrated high efficiency against Culex pipiens (42.60 and 43.61 hours),
and imidacloprid was the least effective (232.08 hours). Whereby, in the
combination with glyphosate, sulfoxaflor + spinetoram and emamectin benzoate
revealed the high potency against Culex pipiens (39.16 and 43.77 hours), and
imidacloprid remain with the same trend of efficacy as least effective selected
insecticide towards Culex pipiens (563.30 hours).
II. Histological and ultrastructural studies on the effect of glyphosate on
the liver of adult albino rats.
1- Light microscopic examination of treated groups:
The liver cells showed vacuolation and the nuclei became small and
deeply stain. The central veins were dilated and congested. Patches of
leucocytic cells mainly lymphocytes between liver cells were observed. After
high dose of treatments (100 mg/kg bwt), most of the liver cells became
completely destroyed leaving large empty spaces. These spaces led to the loss
of the architecture of its normal structure. Increase in number of kupffer cells
which deposit with lipofuscin pigments. The nuclei showed many of
histopathological changes. One of these changes represented by changes in their
color stain and became red in color. The increase of collagenous fibers was
prominent around central veins, portal areas and between liver cells with
increasing the concentration of dose.
2- Transmission electron microscope examination:
Ultrastructure examination revealed that in some cells, the cellular
organelles were clumped beside the nuclei leaving large empty spaces in the
cytoplasm. Sometimes many of the vacuoles and lipid droplets of different size
and shape were increased in the cytoplasm. Moreover, congested blood
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Chapter 5 Summary and Conclusion
sinusoids filled with deformed RBCs. Also, it was observed that the nuclei
became shrinked and sometimes devoid from chromatin.
3- Examination of treated groups histologically and ultrastructure revealed
that, by using of Roundup after a period of treatment (15 days) led to
many harmful effects on normal structure of liver tissue. So we suggest that we should use of Roundup as herbicide in the acceptable daily intake (ADI) plus a good antioxidant to overcome the problems resulted from its side and to look for the best and the safest alternative for human health.