Molluscicidal activity of plants from Puerto Rico.
Overall, 173 tropical plants from 72 different families, collected from the north-western and western regions of Puerto Rico between March 1983 and March 1985, were screened for their molluscicidal properties against Biomphalaria glabrata, the intermediate host of Schistosoma mansoni. Six plant extracts were effective at 50 ppm. The two most effective extracts were those from the leaves of Didymopanax morototoni (Araliaceae) and Mammea americana (Guttiferae), which, at 50 ppm, killed all snails after 24 h of exposure and a day for recovery. Under the same conditions, extracts of Furcraea tuberosa, Argemone mexicana and Paullinia pinnata killed 50% of the snails and that of Solanum americanum killed 33%. The most effective extracts (or their active components or compounds based on them) may have potential as molluscides for the relatively cheap control of human schistosomiasis.