| Journal: |
Zagazig J. Agric. Res.,
faculty of agricultural Zagazig university
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Volume: |
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| Abstract: |
Land snails are considered one of the most destructive agricultural pests. A survey
was carried out on three orchards of fruit trees, namely navel orange, mango, and guava, in Behaira
Governorate from January 2020 to December 2021. It was found that individuals of the brown garden
(chocolate-banded) snail, Eubania vemiculata (Muller), were present in the three orchards throughout
the entire year with varying values according to season and host plant with two phenotypes: banded brown
color and unbanded pale-yellow color. The identified phenotypes varied in percentage occurrence from
one orchard to another. The relative percentages of adults with banded brown color and unbanded
pale-yellow color on navel orange, mango, and guava during 2020 were 51.22% & 48.18 %, 51.13%
& 48.17%, and 56.21% & 43.19%, respectively. While the corresponding values during 2021 were
54.11% & 46.10%, 54.15% & 45.15%, and 52.13% & 47.17%, respectively. Oranges harbored the
highest numbers followed by mango and guava. with mean values of 20.51 (21.47), 14.93 (15.57), and
15.13 (15.56) snails per sample, respectively. The values of E.vermiculata population density
gradually increased after winter months to reach the maximum values during the summer or
autumn months. It was observed that adults were more abundant during the summer months, i.e., June,
July, August, and September. In contrast, juveniles were more prevalent during February, March, and
April. Snails of E. vermiculata laid their eggs for about 3.5 months, starting from mid-October 2020 to
the end-January 2021. The eggs were spherical with a mean diameter of 3.3 ± 0.35 mm. The number
of clutches and eggs laid by E. vermiculata significantly (P≤0.05) changed during the breeding season.
Shell measurements of E. vermiculata showed a mean shell height of 20.20 mm ranging from 16.60 to
23.80 mm, while the mean diameter was 26.65 mm, with a range of 22.70 to 30.60 mm. Shell
thickness ranged between 0.73 to 0.89 mm with a mean of 0.81mm. The mean aperture diameter was
9.04 mm, which ranged between 8.18 to 9.89 mm. On the other hand, the number of whorls ranged
between 4.5 to 6.0. and the animal color is banded brown or unbanded pale yellowish. The
dendrogram of genetic distances among populations based on band polymorphisms generated by
RAPD-PCR using the two primers showed that the two populations (p1& p3) can be identified as the
banded brown phenotype, while the two populations (p2 & p4) can be classified as an unbanded paleyellow phenotype of the land snail, E. vermiculata
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