A Comparative and Phylogenetic Study of the Ditylenchus dipsaci, Ditylenchus destructor and Ditylenchus gigas Populations Occurring in Poland

The genus D itylenchus contains more than 80 recognized nematode species with a very wide host range. The most serious species are D itylenchus dipsaci and D itylenchus destructor . Populations of D . dipsaci species complex were collected from A llium cepa , C ichorium endivia and P hlox paniculata in P oland. The D itylenchus gigas population was collected from V icia faba minor , and populations of D . destructor , from S olanum tuberosum spp. tuberosum . Analyses of the r DNA sequences spanning both ITS 1 and ITS 2 fragment regions were carried out on the collected populations. The obtained DNA sequences were compared with those DNA sequences deposited in G en B ank of populations isolated in other countries. Phylogenetic analysis was performed using the data obtained from the DNA sequence comparisons. The results indicated that there is no clear distinction between E uropean and non‐ E uropean populations within D . dipsaci . The results also showed no clear distinction between populations isolated from different host plant species, including populations found in P oland. The populations of D . destructor described here constitute a common group together with A merican and C hinese populations belonging to the haplotype C of the D . destructor species. On the other hand, the D . gigas population was localized separately from those populations that have been described up until now, from E urope and A frica. This is also the first report on the occurrence of D . gigas in P oland.