The use of Phytolacca dodecandra berries in the control of trematode-transmitting snails in Zimbabwe

Abstract

Phytolacca dodecandra, a plant with berries of a known molluscicidal potency, was cultivated in Chiweshe. Studies on the snail population density of Bulinus globosus and Lymnaea natalensis as well as schistosome infection rates in the former were carried out in two streams, in one of which a water extract of P. dodecandra berries was applied in late April and May 1987. Snail sampling was carried out twice a month from April 1986 to April 1988, that is for 12 months prior to and after the mollusciciding exercise. B. globosus snails obtained from both streams were examined for infection by cercarial shedding before they were returned to their sites of collection. The 8-h water extract of P. dodecandra was applied to human watercontact points. The two applications were aimed at achieving a concentration of 50 mg/1. No snails were recovered from the experimental sites for a period of 7 months after the mollusciciding exercise. Snails were recovered in the treated sites only after the onset of the rainy season.