Nematology, 2011, Vol. 13(8), 977-983 Low temperature survival of post-eclosion stages of the potato rot nematode Ditylenchus destructor Thorne (Tylenchida: Anguinidae) Eha Š VILPONIS 1,∗ , Külli HIIESAAR 1 , Tanel KAART 2 , Luule METSPALU 1 , Marika MÄND 1 , Angela P LOOMI 1 , Ingrid H. WILLIAMS 1 and Anne L UIK 1 1 Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, 51014 Tartu, Estonia 2 Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, 51014 Tartu, Estonia Received: 20 December 2010; revised: 29 March 2011 Accepted for publication: 29 March 2011; available online: 3 June 2011 Summary – The potato rot nematode, Ditylenchus destructor, may experience extreme environmental stress caused by freezing temperatures when overwintering in the field. A series of laboratory experiments were conducted in order to clarify overwintering strategies of the nematode. The current study aimed to examine the cold tolerance of this species in various aqueous environments as well as in plant tissues in order to determine its ability to survive 24 h exposure to subzero temperatures. Cold tolerance of adults and fourth-stage juveniles was significantly lower than that of younger juveniles. The lower lethal temperature of adults was −15 ◦ C. Although external ice formation affects all life stages, a few second-stage juveniles were able to survive temperatures as low as −30 ◦ C. The results expand the current understanding of freezing survival in the potato rot nematode and will lead to better comprehension of its ability to withstand subzero temperature conditions. Keywords – cold tolerance, freezing tolerance, mortality prediction, overwintering. The potato rot nematode, Ditylenchus destructor Thor- ne, can become important as a pest of potatoes at tem- peratures of 15-20 ◦ C and at a relative humidity above 90% (CAB International, 2010). Andersson (1971) sum- marises the results of his study by the statement that, even in heavily infested fields, populations of this nematode can be eradicated or decreased if the field is kept free from biennial or perennial host plants for a few years. However, in current agriculture and horticulture, weeds may play a desirable role, providing diversity, ecosystem functions and supporting many other species (Marshall et al., 2003). Ditylenchus destructor has a very wide range of host plants and fungi, which is why this pest presents a serious threat in newly cultivated fields with an un- recorded cropping history, especially if reduced tillage is practised. A positive relationship between less intensive soil management practices and the incidence of herbiv- orous nematodes has been established by several experi- ments (Thomas, 1977; Hendrix et al., 1986; Hou et al., ∗ Corresponding author, e-mail: eha.svilponis@emu.ee 2010). Thus, potato rot nematode may become an increas- ing problem in contemporary agriculture (Svilponis et al., 2008) even though good phytosanitary practices in seed potato production would greatly assist in escaping eco- nomic damage. Since the potato rot nematode may encounter adverse winter conditions in the field in northern temperate areas, it is necessary to study cold tolerance of the pest in detail. Nematodes that survive low temperatures in their natural habitats are cold tolerant (Wharton, 2002). The main model for studying nematode cold tolerance has been an Antarctic nematode, Panagrolaimus davidi (Wharton, 2002, 2003), which exhibits atypical survival abilities when compared with other species of nematodes (Smith et al., 2008). Most of the experimental data on ditylenchid (stem nematode) cold survival date back 40-50 years. Several authors have observed survival of ditylenchids in field conditions. According to Ustinov and Linnik (1955), © Koninklijke Brill NV, Leiden, 2011 DOI:10.1163/138855411X571812 Also available online - www.brill.nl/nemy 977