Effect of ambient salinity on immobilization of Caenorhabditis elegans by nematocidal agents

The ability of three antinematodal agents to induce paralysis of Caenorhabditis elegans was examined in an aqueous medium with and without the addition of salts. The basic medium was deionized water supplemented, for control purposes, with the phosphate mixture used as a buffering agent in M9 solution. This medium was further supplemented with magnesium sulfate or sodium chloride, or both salts, at the concentrations used in M9. We report that the paralyzing property of ivermectin was enhanced by the presence of salt, while the efficacy of levamisole and chlorpromazine was reduced.