Liu Qi-zhi, Aharon Solomon

Heterorhabditid nematodes are known to be very poor anhydrobiotes and there is a
considerable variation in desiccation tolerance among different heterorhabditid isolates. In the present
study we attempted to elucidate the causes for the variation among heterorhabditid strains in regard to
desiccation tolerance, using a comparative approach. Exposure to 97 % RH for 72 h caused reduction
of 10-25 % in desiccation survival of all the nematode strains. After additional exposure to 85 % RH
for 24 h there was no further viability reduction in steinernematids, whereas, drastically reduced to 30-
50 % in heterorhabditid strains. Nematode initial water contents were similar. After 72 h at 97 % RH
the water contents of all strains were reduced by 20 to 25 % w/w. Further exposure to 85 % RH for 24
h, the heterorhabditis lost additional 22-24 %, the steinernematids however did not lose any significant
amount of water. The concentration of trehalose in the hydrated heterorhabditid strains was lower than
that of the steinernematids. Following 72 h at 97 % RH trehalose levels were not increased
significantly in the hydrated heterorhabditid strains, however it was increased in steinernematids. The
levels of glycogen have been decreased significantly in all tested nematodes.