Diversity and density In-Situ of first recorded terrestrial snails; Helix aspersa and Theba pisana in Bani Walid locality, Misurata Governorate, Libya [electronic resource].

Includes references.

Two land snail species belonging to Order: Pulmonata were recorded in Bani Walid locality, Misurata Governorate, Libya (from September 2009 to August 2010) for the first time and they varied in their incidence and level of infestation, These species were; the brown garden snail, Helix aspersa Muller and the white garden snail, Theba pisana Muller. Four host plants were infested with the two species, these plants were; alfalfa, Medicago sativa; barley, Hordenum vulgares; date palm, Phoenix dactylifera and olive, Olea europae, Alfalfa harbored the highest numbers of snail species 20.73 and 33,39 while, the least population density were observed on barley 11.2 and 13,86, H. aspersa was the most abundant species on fruit trees since, it was estimated on date palm. and olive trees more denser than T. pisana while, vice versa was detected on field crops with alfalfa and barley. Values of population density were gradually increased after winter months to reach the maximum during spring and summer months. Moreover, Temperature and relative humidity showed variable effects on population density of the two snail species. . Index of clumping and index of crowding were used to describe distribution types of H. aspersa and T. pisana on certain crops. When comparing frequency occurrence and population density of snail species it gave different results. Therefore, they can be combined together in prominence value. Snail species could be arranged descendingly according to their prominence values such as follows: T. pisana > H. aspersa on alfalfa and barley. While, H. aspersa > T. pisana on date palm and olive trees. Key words: Terrestrial snails. prominence value, Helix aspersa and Thebaisana.

Summary in Arabic.

1