Natural dehydration regimes as a prerequisite for the successful induction of anhydrobiosis in the nematode Rotylenchulus reniformis.

Induction of anhydrobiosis in the nematode Rotylenchulus reniformis (Linford & Oliveira) was studied using direct exposure to elevated relative humidities and conditions resembling natural dehydration regimes. All larvae and preadults were unable to survive direct short-term exposure to 97% relative humidity. However, dehydration of larvae on model substrates (0.5% agar: 1.0% agarose) that mimic the natural rate of soil moisture loss induced coiling and successful entry into anhydrobiosis. Coiling was maximized at 10-12 days and only coiled larvae survived dehydration, emerging as the preadult form. Larvae could withstand severe dehydration at 80 and 40% relative humidity after the induction of coiling, but were unable to withstand direct exposure to 0% relative humidity. The levels of adaptation utilized by anhydrobiotes to ensure slow dehydration and the adaptive significance of this are discussed in relation to the different environments in which these organisms are found. The results suggest that R. reniformis is well-adapted to its environment and emphasize the importance of natural dehydration regimes for assessing anhydrobiotic potential.