Observations on the desiccation survival of second stage juveniles of the rice cyst nematodes, Heterodera sacchari, H. Oryzae and H. Oryzicola

The effects of different relative humidities (RH) on the survival of second stage juveniles (J2) of Heterodera sacchari, H. oryzae and H. oryzicola were examined. Hatched juveniles were able to withstand desiccation at all humidities tested for minutes only; H. oryzae was slightly better at surviving desiccation than the other two species. J2 were able to survive longer periods of desiccation inside the egg-shell compared with free J2. An examination of the rate of water loss of hatched H. sacchari and H. oryzicola at different RHs showed that both species were unable to control their rate of drying, especially at low RH, and were dependent on high humidity (98% RH) for slow water loss. The results indicate that these nematodes have no intrinsic ability to control water loss and survive desiccation.