Preliminary evaluation of some wild and cultivated plants for snail control in Machakos District, Kenya.

Fifty local medicinal, agricultural and wild growing deciduous plants, representing 49 species, 46 genera and 22 families, were screened as water extracts at 1:1000 concentration for molluscicidal activity against Biomphalaria pfeifferi in Machakos District, Kenya. Forty-seven of the 50 (94%) plants and 106 of the 134 (79%) plant materials (roots, stems, leaves, fruits, flowers and seeds) were molluscicidal. The leaves of Pappea capensis (Sapindaceae), Steganotaenia araliacea (Umbelliferae), Zornia setosa subsp. obvata (Papilionaceae) and Terminalia kilimandscharica (Combretaceae), the flower pods of Hyptis pectinata (Labiatae), the seeds of Acacia nilotica (Mimosaceae) and the fruits and roots of Solanum nigrum (Solanaceae) gave 100% kill. Another 15 species produced mortality rates between 53% and 87%. Plants were evaluated for possible use in local snail control programmes by considering their growing characteristics, habitat requirements, toxicity in non-target organisms, abundance in the study area and competing uses.