Activity and Survival of Orrina phyllobia: Preliminary Investigations on the Effects of Solutes.

The motility and survival of Orrina phyllobia fourth-stage juveniles (J4) were examined in NaCl, sucrose, and synthetic soil solutions. Synthetic soil solutions (SSSs) contained Na, K, Ca(2), Mg(2), Cl, and NO at relative concentrations identical to those in a known agronomic soil. Nematode activity was dependent on solute composition and on water potential. In all solutions, motility ceased at a water potential of -30 x 10 Pa and nematodes partially desiccated. Activity inhibition in NaCl began at -5 x 10 Pa. At -15 x 10 Pa, a high level of activity was sustained only in SSS. Lethal effects occurred at -15 and -60 x 10 Pa in NaCl and SSS, respectively. No lethal effects were measured in sucrose solutions. Hydrogen ion concentration over the pH range 4.5-9.5 had no measurable effect on nematode activity.