Effects of Cyanide Ion and Hypoxia on the Volumes of Second-Stage Juveniles of Meloidogyne incognita in Polyethylene Glycol Solutions.

Changes in the volumes of second-stage juveniles of Meloidogyne incognita were monitored in aqueous solutions of polyethylene glycol supplemented with dilute balanced salts. At key points within a 48-hour cycle of fluctuating water potential, nematodes were placed under hypoxic conditions or exposed to the respiratory inhibitor, sodium cyanide, to detect any respiration-dependent process that regulates volume. Aerobic respiratory arrest at -500 kPa induced pronounced water loss, lateral and dorsoventral collapse of the body wall, and abnormal failure to shorten longitudinally. Durations of hypoxia that were innocuous in dilute solutions were lethal during 500 kPa increases and decreases in water potential; the same water potential changes under aerobic conditions had no effect on viability. Data are consistent with the hypothesis that respiration is essential to survive water potential changes.