Reham Fathey

Biological aspects of the terrestrial garden slug Deroceras laeve including oviposition, hatching, generation period, life span as well as growth parameters were studied under laboratory conditions. Results revealed that mating is not essential for this species to lay eggs, while self-fertilization is the normal breeding system. The oviposition period averaged 33.6 days, during which the individual laid an average of 34.5 eggs. The incubation period averaged 18.2 days. While the generation period (from egg to egg) lasted 83.3 days in average. On the other hand, the maximum life span durated an average of 135.9 days.
Growth parameters, depending on the increase and decrease of slug body weights, rapidly increased during the first two months of the age, and then gradually decreased.

Mating, pre-oviposition, oviposition, post-oviposition, and generation periods as well as growth rate of the pointed or conical snail Cochlicella acuta (Müller, 1774) were studied in Egypt under laboratory conditions during its reproductive and activity season of 2008/ 2009. In spite of this species is hermaphroditic, the laboratory observations indicated that cross mating was essential for oviposition as unmated snails did not lay any egg. Mating occurs when snail individuals reach their sexual maturity as calculated from adulthood till mating. This period was 99.2 ± 23.8 days in average. Pre-oviposition period (from mating till laying first egg) lasted for an average of 17.6 ± 6.1 days. Oviposition period (from laying first egg till last one) averaged 86.3 ± 22.5 days during which snail individual deposited a total of 113.3 ± 58.3 eggs. Post-oviposition period (from last laid egg till mortality) was 140.7 ± 74.3 days. The generation period (from egg to egg) of this species extended to an average of 283.7 ± 29.3 days.

Mating, oviposition, post-oviposition period, development, and generation period of the two land snail species Monacha cartusiana (Müller) and Eobania vermiculata (Müller) were studied in the laboratory in Egypt during the two seasons of 2003/4 and 2004/5. Data revealed that mating is essential for both snail species to lay eggs, thus it occurs when snails reached their sexual maturity (from adulthood till mating) during a period averaged 190.3 and 228.6 days for M. cartusiana and 231.6 and 568.3 days for E. vermiculata after adulthood in the two different seasons respectively. Pre-oviposition period (from mating till laying first egg) lasted an average of 2.7 and 8.2 days for M. cartusiana and 3.5 and 9.2 days for E. vermiculata during the two seasons respectively.
Oviposition period (from first laying egg till last one) averaged 22.5 and 64.1 days during which the snail of M. cartusiana deposited an average of 63.0 and 177.5 eggs during the two seasons respectively. On the other hand this period averaged 15.2 and 24.9 days for E. vermiculata during which the snail individual deposited and total average of 89.6 and 162.0 eggs during 2003/4 and 2004/5 respectively. While, post-oviposition period (from last egg till death) lasted 142.4 and 71.9 days for first snail species and 372.5 and 660.1 days for the second one during the same seasons respectively. The generation period (from egg to egg) extended an average of 369.8 and 402.6 and 481.7 and 868.7 days for both species during the same seasons respectively.