(4(4):39-45)Calcium Cyanamide as a Repellent and Contact Poison against the Giant African Snail (Preliminary Note)

A series of preliminary tests made at Taipei, Formosa in 1950 revealed that calcium cyanamide is a promising repellent as well as contact poison against the giant african snail, Achatina fulica Ferussac, which was introduce into this island in 1932 and is at present one of the major pests everywhere below the level of 1,000 meters. To avoid its harmfulness to plants by direct contact, it is suggested that the application of this chemical should be in the form of 6 cm. wide harrier surrounding the plants to be protected. Each meter of such barrier requires 60 to 80 g. of calcium cyanamide. As a contact poison, it can be applied regardless of the weather conditions. Its effectiveness as a repellent, however, is weaker in rainy days and lasts 2 or 3 days. Under experimental conditions, about 16%(in fine clays) and 50%(in rainy days) of the adult snails encircled therewithin were able to ”break through” the calcium cyanamide barrier, and about 70% era killed within 3 to 5 days. Prematured eggs were laid, usually 43 hrs. after the snail got in direct contact with the poison, but failed to hatch. Besides its effectiveness as a repellent and contact poison against the snail, and also as a fertilizer to plants, calcium cyanamide has the advantage in being cheap, readlly available in rural countries and simple in practice