Effect of abiotic factors on the molluscicidal activity of oleoresin of Zingiber officinale against the snail Lymnaea acuminata

摘要

Earlier it has been observed that oleoresin of Zingiber officinale is a potent molluscicide ag- ainst Lymnaea acuminata. This snail is the vector of Fasciola species, which cause ende- mic fascioliasis in eastern Uttar Pradesh. As this snail breeds and maintain their population constant through out the year, so that the present study has been designed to find out the effect of variations in some environmental factors in different seasons, on the molluscicidal activity of oleoresin of Zingiber officinale and its relative effect on certain enzymes viz., acetylcholinesterase, acid and alkaline phosphatases in the nervous tissue of the snail Lymnaea acuminata. In this study temperature, pH, dissolve oxygen, free carbon dioxide, conductivity of the water in control, as well as molluscicide treated water, was measured simultaneously. LC50 value of oleoresin was determined in each month of the year. Toxicity of oleoresin in June-July (24 h LC50 16.54-14.28 mgL-1) is highest. Acetylcholinesterase, acid and alkaline phosphatases activity in the nervous tissue of the snails treated with sub-lethal concentration of oleoresin was simultaneously measured. Sig- nificant positive rank correlation, in between the acetylcholinesterase or acid phosphatase activity and LC50 of oleoresin was observed. The pre- sent study conclusively shows that variant abi- otic factors can significantly alter the toxicity of oleoresin of Z. officinale in L. acuminata. The most suitable period for control of L. acuminata is June-July.