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A method has been developed for the study of genetic relationships among Globodera pallida, microscopic phytonematodes, populations. Quantitative analysis has been carried out in two-dimensional gel electrophoresis protein patterns. Results were compared with those from traditional allele frequency analysis (AFA), and it was concluded that quantitative protein analysis can be used successfully for phylogenetic analysis for G. pallida populations.

Molecular approaches have been used to study taxonomy of Peruvian potato cyst nematodes and gene pool similarities in populations of Globodera, both imported and native. It was a surprise to see that although random amplified polymorphic DNA (RAPD) showed a higher variability in the Peruvian group than in the European one, some characteristic proteins were found using 2-DGE in some European populations although it was not possible to find any in the Peruvian ones.

Life cycle variation and genetic structure are discussed as seen in nematode populations. Little available data on population genetic structure in nematode species allows direct comparison of genetic structure of species which have different life cycles. A study using mtDNA sequence data has been carried out to look at genetic structure of a heterorhabditid nematode. Results are compared to data from the literature related to other species.

Two important race groups of the stem nematode, Ditylenchus dipsaci, an obligatory polyphagous endoparasite, attack the bean, Vicia faba. Morphological differences have been found in the two groups and there were corresponding differences in faba bean disease symptoms. Agreement has been found between RAPD and phenotypic characteristics in the nematodes. Variation between D. dipsaci species in populations involved with V. faba was low. No strong correlation was found between geographical origin and morphological or molecular characteristics.

A study is made regarding how the genetic diversity of pinewood nematode has changed during the invasion process, and how pinewood nematode spread among geographical regions in China. Result suggests that reinforcement of quarantine is essential to control the spread of pinewood nematode and should include both international quarantine and domestic quarantine.

The influence of temperature on the genetic correlations between egg size, egg number and body mass in the nematode Caenorhabditis elegans is studied. Results indicated that specific loci control the covariation in the life-history traits and the locus control is prone to environmental conditions.