Action of the herbicide butachlor on cholinesterases in the freshwater snail Pila globosa (Swainson).

Butachlor action on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activates in central nervous tissue of the snail Pila globosa was assayed following the method of ELLMAN et al1, in vitro by adding butachlor directly (10-100 mu moles), to tissue homogenates and in in vivo by exposing the snails to sub-lethal concentration (26.6 ppm) and taking out the tissue for experimentation at different intervals (3, 6, 12, 24 and 48 h) of exposure. The enzyme activities decreased in a dose-dependent manner in vitro, and up to 12-24 h in vivo after which they showed recovery towards the control. The inhibition of cholinesterases by butachlor in vitro indicates a direct action of the herbicide on these enzymes. Presumably butachlor exercises its neurotoxic effects through cholinergic impairment in a way similar to that of organophosphates and carbamates.