A Preliminary Screening of the Molluscicidal Activity of Coleus Blumei Bentham, Pittosporum resinferum Hemsley AND Sanseviera sp. Thunberg ON Oncomelania hupensis quadrasi Moellendorff

Abstract

The molluscicidal activity of Coleus blumei Benth., Pittosporum resiniferum Hemsl. and Sanseviera sp. Thunberg against Oncomelania hupensis quadrasi Moell. was investigated using niclosamide as positive control. One hundred percent crude extract of Coleus blumei Benth. was used against the snails. Snail activity was retarded on the first six hours after which fluctuations in activity were observed. Snail mortality is six percent. One percent crude extract and supernate were prepared from Pittosporum resiniferum Hemsl. fruit extract. Pittosporum resiniferum Hemsl. crude extract showed a fluctuating trend in snail activity. The supernate retarded snail activity for the first six hours after which fluctuations in snail activity also occurred. Snail mortality for both crude extract and supernate is two percent. One percent Sanseviera sp. Thunberg, on both primary and secondary tests showed an initial retardation of snail activity on the first six hours. Fluctuations in snail activity were observed until the end of the observation period. Mortality is sixty percent and sixteen percent on the primary test and secondary test, respectively. The difference may be accounted for a) the snail source and b) the probable decrease in potency of Sanseviera sp. Thunberg extract through time. Niclosamide at 10 ppm exhibited total retardation of snail activity in two hours. Furthermore, ninety-eight percent mortality was observed. Niclosamide still remains to be the molluscicide of choice.