STUDIES ON THE SEASONAL ABUNDANCE OF LAND SNAILS ON DATE PALM SHOOTS IN SHARKIA GOVERNORATE

In Sharkia Governorate, date palm shoots are subjected to severe infestation with the three dominating land snail species, Helicelfa vestalis (Pfeiffer), Cochlicella acuta (Muller) and Theba pisana (Muller (Pulmonata : Helicidae). Monitoring land snail populations was carried out during the two successive years, 1991 and 1992. The commencement dates and peaks of snail activity were recorded and the seasonal broods were ap­proximated. Snails were noticed on date palm shoots from January to December for H. vestalis and C. acuta, and from February to November for T. pisana. H. vestalis was the most abundant snail on date palm shoots allover the year round where the cumulative mean number being 564.0-597.0 individuals per shoot, followed by C.acuta (495.7-523.9 in­dividuals) then T. pisana (303.0-346.9 individuals) for 1991 and 1992, respectively. For the three snail species, spring, summer and autmn sea­sons showed the maximum abundance (477.4-526.4, 400.6-405.3 and 396.6-442.8 individuals per shoot), while winter was the least (88.1 -93.3) during the respective two years. The effect of temperature and relative humidity on land snails activity was statistically studied.