TRIALS OF TWO NEW MOLLUSCICIDES, BAYER 73 AND SEVIN. AGAINST ONCOMELANIA NOSOPHORA, A SNAIL INTERMEDIATE HOST OF SCHISTOSOMA JAPONICUM IN JAPAN

Preliminary laboratory and field tests with a new molluscicide, Bayer 73 (5, 2-dichloro-4-nitro-salicylicanilide), were reported by Gönnert et al, in 1948. Since then, this compound has been tested on aquatic snails transmitting Schistosoma mansoni and S. haematobium, both in the laboratory and in the field. However, very little is known of the effect of the compound on amphibious snails transmitting S. japonicum. Another chemical, Sevin (1-naphthyl N-methylcarbamate) has been used as a very promising insecticide. Data are, however, not yet available as to whether Sevin could be applied as a molluscicide against schistosome bearing snails. The aim of this study is to examine the molluscicidal activity of both compounds, Bayer 73 and Sevin, against O. nosophora, the vector snail of Schistosoma japonicum, under laboratory and field conditions.