الفهرس 
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Abstract
SUMMARY
The possibility of using the bacterial mosquito larvicid Bacillus
sphaericus in controling the kpipiens larvae and A. caspius larvae was
studied. It is one of the most safe biological agents for human being
and animals to decrease the use of chemical insectecides and prevent
the environmental polution.
The obtained results indicated the following :
_ The results indicated that the C. pipiens larvae was more susceptable
to the bacterial larvicide Bacillus sphaericus than A. caspius larvae.
_ The dosage levels of this bacteria have great influence in its toxicity,
high concentrations evoked a rapid lethal response to the entire
tested larvae, while low dosage resulted in significant mortality
rates with increasing exposure time and water temperature.
Biochemical approaches have been developed to increase the
activity of Bacillus sphaericus against the Culex larvae and Aedes
larvae. These approaches were based on the incorporation of some
selected non-toxic chemical compounds with the bacterial
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larvicide, these compounds may increase the rate of which larvae
ingest the particles of bacteria (phagostimulation) therefore high
level of larval mortality was obtained.
The compounds used was inorganic salts, organic acids and their
salts and amino acids, some of these compounds showed a
remarkable potentiation to the Bacillus sphaericus activity against
the Culex larvae and Aedes larvae.
_ It was found that some additives such as sucarose, fractose, glucose,
maltose, sorbetol, mannose, molasses, yeast extract, fish meal,
larval extract and soyabean powder improve the efficacy of
Bacillus sphaericus against the Culex pipiens larvae, that due to
their phagostimulation effect.
_ Due to the fact that the persistence of Bacillus sphaericus is very
short in the field as a result of exposure to ultraviolet radiation
various approaches have been adopted in the present study in
attempts to increase the persistence of this pathogen to increase its
potentiation against the Culex pipiens larvae.
_ Laboratory investigations, indicated that the activity of Bacillus
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sphaericus suspension exposed to ultraviolet radiation, can be
prolonged after the addition of certain photoprotectants which
reduced the effect of U.V-rays on bacterial larvicides. These
materials, such as charcoal, chines ink, talc, chalk. The results
indicated that charcoal and chines ink had high absorbance values
to U.Y-rays, they are also inert, cheap, so they can be used as a
good photoprotectant to Bacillus sphaericus from the ultraviolet
radiation, and that increase its potentiation against the Culex
pipiens larvae.
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