Comparison among the Toxicity of Thymol and Certain Pesticides on Adults Survival and Egg Hatchability of the Glassy Clover Snail Monacha cartusiana (MÜLLER)

Land gastropods have become important economic pests attacking various vegetation in Egypt. This study aimed to determine the molluscicidal activity of the monoterpenoids compound, Thymol and three pesticides (Neomyl, Kafrothrin and Round up) against adult's survival and egg hatchability of the glassy clover snail Monachacartusiana under laboratory and field conditions. Poisonous baits technique gave better results than did leaf dipping technique. The obtained results indicated that Neomyl was the most effective one followed by Thymol and Kafrothrin then Round up which had the lowest affect against the adult of M. cartusianawith LC50 0.79, 1.78, 3.62 and 0.49 ppm respectively. Also, Neomyl was the most effective one on the incubation period of eggs of M. cartusiana(25 days in average) followed by Thymol (23.5 days in average), Kafrothrin (23 days in average) and Round up (22 days in average). Similar trend was noticed with mean egg hatchability with values of 1.0, 1.8, 3.0 and 4.4, respectively. In field experiment represented using poisonous baits of such compounds Neomyl (72.61%) gave the highest reduction percentage in Egyptian clover fields naturally infested with M. cartusiana followed by Thymol (55.82%) and Kafrothrin (50.03%) then Round up (17.20%). The obtained results proved that the use of Thymol in controlling harmful land snail would achieve effectiveness comparable to synthetic molluscicides.