Studies On an Artificially Fragmented Population of Potato Cyst Nematode Globodera Pallida

A series of sub-populations was produced from a population of Globodera pallida by raising single cyst progenies on three susceptible potato cultivars. After completion of each generation, single cysts were taken to produce the next generation. Six generations were completed and then the resulting sub-populations were multiplied on the susceptible cultivar Ddsir6e. A sample of these sub-populations was then used to conduct a virulence test and to investigate the genetic variation among the sub-populations. The virulence test showed that the susceptible cultivar used in the generation of these sub-populations had a marked effect on the general reproductive capability of the sub-populations and that there was a range of variation in virulence on partially resistant clones. A RAPD study revealed that the range of genetic variation among these sub-populations was comparable to that shown between field populations in other studies and that there was a tendency for the sub-populations to be grouped in relation to the susceptible cultivar they were reared on. These results from an artificially fragmented population are discussed in relation to the introduction and spread of potato cyst nematodes in Europe.