Dehydration tolerance and water vapour absorption in two species of soil-dwelling Collembola by accumulation of sugars and polyols

1. Physiological and biochemical responses to desiccation were studied in t wo species of hygrophilic Collembola, Folsomia fimetaria L. and Protaphorur a armata Tullberg. The temporal changes in water content, body fluid osmoti c pressure, and accumulation of sugars and polyols during desiccation stres s, equivalent to severe soil drought are reported. 2. Both species initially lost about 50% of their initial content of osmoti cally active water. Within 7 days F fimetaria had re-established their prel iminary water content by absorbing water vapour from the atmosphere. Protap horura armata also significantly increased their water content over the fol lowing 10 days. 3. Both species were able to resume their hyperosmotic status relative to t he desiccating environment they were placed in. The accumulation of myo-ino sitol and two other unidentified compounds (F fimetaria) and trehalose (P. armata) made an important contribution to this phenomenon. 4. These results suggest that water vapour absorption by accumulation of su gars and polyols may be widespread in soil-dwelling Collembola.