الفهرس 
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Abstract
Land snails become the most important agricultural pest in the world. It caused large damage to the different crops this by feeding on
its roots, stems, leaves and fruits. In recent years it was increased in
Egypt, so that we must make a lot of studies for control it’s dispersion
and this occurred by studying all thing about it’s life and make a
suitable programs for managing it. from old years most management
programs of land snails depend on the using of the chemical pesticides
which represent the main reason of the environmental pollution, this
by it’s accumulation in soil, water, air and in the agricultural products.
All this disadvantages leads to searching for a new safely methods for
the management of this pest, specially the biological control using the
microorganisms. The results of this study cleared that:
(I) Ecological studies on land snails:
(1) The ecological studies of the occurrence and dispersion of the
land snails in 6 districts in Sharkia Governorate cleared that
the land snail Monacha cartusiana was the only snail which
found in the all surveyed districts. While Succinia putris land
snail was appeared only one time as one snail in Fakos district.
(2) The population dynamics studies of the land snail Monacha
cartusiana on some field citrus trees during the period
January 2011 to December 2011 showed that the highest
number of this snail was recorded in April on navel orange,
then decreased gradually and reached to the lowest number in
September and on the navel orange in August.
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Summary
(II) Microbiological study:
The microorganisms which present on shells, gastropods, and
juveniles at Monacha cartusiana snails were studied. The result
recorded that 7 genera of fungi and 5 genera of bacteria were isolated
from the snails. Acremonium, Aspergillus, Penicillium, Blastomyces,
Fusarium, Trichoderma and Candida were isolated from all stages
and adult snails. The studies also showed 5 bacteria isolated from M.
cartusiana; B. thuringensis, E. coli, Pseudomonas, Klebsiella and
Shigella were isolated from M. cartusiana snails.
Post-treatment in laboratory 3 x 105 spores/ml of Aspergillus
flavus causing highest mortality 30% to M. cartusiana snails
wherever the Bacillus thuringiensis causing highest bacteria causing
mortality reached 100% to M. cartusiana snails and other bacteria
causing 50%, 10%, zero% and zero% mortality for E. coli, Klebsiella,
Pseudomonas and Shigella respectively.
The morphological and biochemical characterization for the
identification of Bacillus thuringiensis isolates revealed that the whole
isolate of Bacillus thuringensis belonging to Subsp. Kurstaki (Es+ Sa+,
Le+ and Su-).
Most strain of isolates strain produce a typical crystal often
heterogenous in size and shape.
All Bacillus thuringiensis isolate were characterized by PCR.
Parasporal bodies of Bacillus thuringiensis isolate had biological
activity when assayed against Monacha cartusiana snails. The protein
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Summary
composition of parasporal bodies 140 kilo Dalton (KDa). Parasporal
bodies caused mortality reached 100% to Monacha cartusiana snails
by concentration 7.8 mg/ml.
Field application of Bacillus thuringensis as toxic spray on citrus
trees of infected parts with adults of Monacha cartusiana snails by
using 2 x 103 c.f.u/ml showed that mortality reached 89% of snails
after 21 day.
(III) Histopathological Studies:
Indicated that following oral administration of Bacillus thuringensis
the general architecture of digestive glands lost its normal appearance.
The damage acini in treated snails including narrowing in acinar
lumen, atrophied acini and acini became study to each other with
disturbed architecture acini, disappearance of glandular and calcium
cells. Snails stooped feeding and lost the appetite with very sluggish
movement.
It can be concluded that:
1- Bacillus thuringensis (Bt) are bactericidal caused mortality
reached 100% after 21 days post treatment with concentration
2 x 103 c.f.u/ml.
2- The concentration of parasporal bodies of (Bt) killed 100 snails
with concentration 7.8 mg/ml.