Water relations during desiccation of cysts of the potato-cyst nematode Globodera rostochiensis

The loss during desiccation of osmotically active water (OAW), which freeze s during cooling to -45 degreesC, and osmotically inactive water (OIW), whi ch remains unfrozen. from the cysts of the potato cyst nematode, Globodera rostochiensis, was determined using differential scanning calorimetry. Exot herms and endotherms associated with non-egg compartments were not detected after 5 min desiccation at 50% relative humidity and 20 degreesC. The patt ern of water loss from the cysts indicates that water is lost from compartm ents outside the eggs first, that nearly all the non-egg water is OAW and t hat the OIW content of the cyst is contained within the eggs. Water is lost from the eggs only after the OAW content outside the eggs falls below that within the eggs, Both OAW and OIW are lost from the eggs during desiccatio n but the eggs retain a small amount of OIW. Other animals which survive so me desiccation but which are not anhydrobiotic will tolerate the loss of OA W but not the loss of their OIW. Anhydrobiotic animals can survive the loss of both their OAW and a substantial proportion of their OIW.