Communities of free living and plant parasitic nematodes in hop gardens in Slovakia

A total of 61 nematode species belonging into 48 genera was identified in soil of nine localities of hop gardens in Slovakia. From free living soil nematodes the most abundant were the genus Rhabditis-eudominant taxon, species Aphelenchus avenae — dominant taxon, the species Cephalobus persegnis, Chiloplacus propinquus, Aglenchus agricola, Nothotylenchus acris, Aporcelaimellus obtusicaudatus and genus Eudorylaimus were subdominant taxa. Only ten species of plant parasitic nematodes were observed — Ditylenchus dipsaci, Bitylenchus dubius, Merlinius brevidens, Rotylenchus robustus, Helicotylenchus canadensis, H. digonicus, Pratylenchus penetrans, P. pratensis, Heterodera humuli, and Paratylenchus bukowinensis. Bitylenchus dubius and Merlinius brevidens belonged to dominant taxa, the species Heterodera humuli and Helicotylenchus digonicus to subdominant taxa. The occurrence of Heterodera humuli cysts was recorded at all localities studied, and the occurrence of H. humuli larvae in soil during autumn indicates that possibly more than one generation of the parasite have developed within one vegetation period. The proportion of individual trophic groups in nematode communities of hop gardens was characterised by the prevalence of bacterial feeders followed by plant parasites. The ecological characteristics used for ecological evaluation, especially Maturity Index and Plant Parasitic Index/Maturity Index, indicate a more disturbed environment. Although hop is a perennial plant, the structure and ecology of its nematode communities is more similar to the agricultural ecosystems with a higher level of agricultural practices.