The Influence of Pre-Incubation of Labronema Digitatum At Different Ionic Concentrations To Subsequent Electrotaxis

The soil-inhabiting nematode Labronema digitatum, when exposed to an electric field at 0.06 mA of current, migrated to the cathode in tap water and also in solutions of NiCl2, MnCl2 and ZnCl2 at the salt concentration of tap water (34 × 10-2 to 42 × 10-2 g/l) . The nematodes showed cathodic electrotaxis at all concentrations between 2 × 10-3 and 50 × 10-1 g/l of those salt solutions only when they were pre-incubated in the test concentration for 1 h. No pre-incubation was required for electrotactic response in tap water because the nematodes are normally adapted to the ionic concentration of tap water in their natural soil environment. It is suggested that necessary adjustment with respect to the balance in osmotic pressure between the body fluid of nematodes and the ambient medium is a necessary prerequisite during preincubation in the test concentrations.