Anhydrobiosis in Pratylenchus penetrans.

Anhydrobiotic survival of Pratylenchus penetrans was compared in several soil moisture regimes. Bodies of anhydrobiotic nematodes were coiled. In slow-dried soils, Vineland silt loam (VSL) and Fox loamy sand (FLS), 70 and 58% of the total P. penetrans populations were anhydrobiotic when soil moistures reached ca. 3% and water potential 15 kPa or greater. Coiling began at a much lower water potential in FLS than in VSL. In fast-dried soils, only 31 and 22% of the P. penetrans populations in the same two soil types had entered the anhydrobiotic state at comparable moistures. In the above soils, 76-96% of the P. penetrans were alive immediately after entering the anhydrobiotic state. In slow-dried VSL, some nematodes (1%) survived 770 days. In the other soils, all anhydrobiotic nematodes were dead after 438 days. Anhydrobiosis increased the ability of nematodes to survive subzero temperatures, but it did not increase their ability to survive temperatures above 40 C. Infectivity and reproductivity of rehydrated P. penetrans were not affected by anhydrobiosis.