This present study was aimed at assessing the toxicological effects of the leaf extracts of Picralima nitida on aspects of the biology of Lanistes varicus. The extraction of the leaf, biochemical parameters and toxicity tests were performed using standard methods.. Acetylcholinesterase's activity was mostly inhibited in the snail's intestine and haemolymph by the aqueous extract and in the hepatopancreas by ethanol extract. The total protein level of the snail was mostly decreased in the haemolymph by the ethanol extract while in the hepatopancreas, it was mainly decreased by the aqueous extract. There was decrease in the total protein levels of muscle, haemolymph, hepatopancreas and intestine in comparison with the control groups. There were significant (p < 0.05) decreases in the acid phosphatase activity in all the tissues, especially hepatopancreas, intestine and muscle, of the treated groups, compared to the control. Significant (p < 0.05) decreases were observed in the alkaline phosphatase activity in the haemolymph, hepatopancreas and intestine of all the treated groups. Exposure to increasing concentrations of the extracts, especially the ethanol extract, brought about induction of production of male sex hormone in snails. The study provides a scientific basis for exploiting local and indigenous plant resources in Nigeria for the control of freshwater snails and trematode borne infections.
