Abstract

Evaporated and unevaporated extracts were prepared from both dried and fresh leaves sample and subjected to a 24 h static bioassay. A reference molluscicide niclosamide (Baylusicide) was used as standard and rainwater as untreated control. Reaction of the snails on coming in contact with the test medium is either shock or distress. The distress reaction started with retraction of tentacles and ended in some cases with death. Shock reaction results when snails are immersed in a more concentrated crude water extract which usually resulted in the death of the snails. Statistical analysis of average mortality figures by the use of probit gave LC₅₀ of 40.42 (35.15 – 46.47) for the unevaporated crude water while the evaporated crude water extract had LC₅₀ of 48.07 (42.81 – 54.28) for the dried leaf extract. For the fresh leaves the unevaporated crude water extract had LC₅₀ of 32.57 (27.15 – 39.08) and evaporated crude water gave 45.00 (39.09 – 51.79). This results show that the molluscicidal properties of the leaf extract was dose dependent as mortality increases with the relative increase in concentration of the extract. Furthermore, the bioavailability of the active component is more in the fresh leaves sample when compared to the lethal concentration values of the dried leaves extract and the potential of the crude water extract in integrated schitosomiasis control is discussed.

Key words: Alternanthera sesselis, crude water extract, molluscicidal activity, bioavailability, schistomiasis control.