Biology, food consumption and control of the gray garden slug deroceras reticulatum

Hend sh. Ghareeb

Abstract

Biological, food consumption and control studies were investigated against the gray garden slug, Deroceras reticulatum (Müller) under laboratory conditions. Results show that slugs began egg – laying in early January, and deposited clusters each containing from 21 to 43 oval eggs in or a top the soil. Eggs measured about 2 mm in length and 3 mm in width. The transformation being seen through a change of eggs color, from a white color into a pale buff after a week of egg laying. Eggs take from 23 to 27 days to hatch and the hatching period ranged between 6 to 11 days. Hatchability varied between 79% and 97.3%. Average life span was 55.3 weeks and the post oviposition period recorded about 69.6 days. The mean generation time varied between 50 and 52 weeks. These results indicate that D. reticulatum has one generation per year. The amount of leaf tissue consumed per day by adult slugs was more than the other which consumed by juveniles. 0.45, 0.28, 0.18 and 0.16 mg were the means of food consumed by juveniles for potato, cabbage, carrots and lettuce, respectively. In case of adults, the highest food consumption was recorded for cabbage by mean 1.14 mg followed by potato, carrots and lettuce by means 0.88, 0.40 and 0.20 mg, respectively. Ammonium hydroxide, calcium carbonate, onion juice and potassium chloride were tested against D. reticulatum eggs at different dipping periods 10, 20, 30, 40 and 50 seconds. Ammonium hydroxide exhibited the highest effect against eggs by preventing its hatching at the concentration 1.5% for dipping period 20 seconds. Onion juice gave the same effect at 2% concentration and 30 seconds dipping period. No hatching occurred also in case of potassium chloride at 1.5% concentration and dipping period 40 seconds. Calcium carbonate showed the lowest effect against eggs.

Key words

Deroceras reticulatum, biology, food consumption, eggs, Control.