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

A. F. Robinson, C. C. Orr, C. E. Heintz

Abstract


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[sup+], K[sup+], Ca²[sup+], Mg²[sup+], Cl[sup-], and NO[sub3][sup-] 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 × 10[sup5] Pa and nematodes partially desiccated. Activity inhibition in NaC1 began at -5 × 10[sup5] Pa. At -15 × 10[sup5] Pa, a high level of activity was sustained only in SSS. Lethal effects occurred at -15 and -60 × 10[sup5] 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. Key words: osmolality, water potential, ionic solutes.

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