Laboratory and field assessment of the molluscicidal activity of gogo (Entada phaseoloides) against the amphibious snail intermediate host of Schistosoma japonicum.

A molluscicidal fraction occurs naturally in the bark of a vine (gogo in Tagalog), Entada phaseoloides, which grows indigeneously and abundantly in the Philippines. Butanol fraction of the methanol extracts of the bark was most toxic against Oncomelania quadrasi with the LC50 of 3.6-5.8 ppm. Analytical work on the butanol fraction by thin layer chromatography indicated that the active molluscicidal agents contained at least two kinds of saponins. The potency of E. phaseoloides remained rather stable over a wide range of pH values, in the presence of minerals and yeast cells and after ultraviolet irradiation of solutions. Our preliminary field trials, however, showed that doses as higher than 40 g per square meter would be needed to produce a satisfactory molluscicidal effect under field conditions.