Diagnostics of cyst nematodes: use of the polymerase chain reaction to determine species and estimate population levels

The effective management of cyst nematodes requires accurate assessments of the species composition and size of field populations. Compared to traditional diagnostics the polymerase chain reaction offers high specificity, sensitivity and a more rapid means of identifying large numbers of cyst nematode samples. PCRRFLP of the ITS I ribosomal DNA region from Heterodera and Globodera species produced diagnostic profiles that allowed identification of six pest species. Quantitative PCR was assessed as a means of determining the population sizes of cyst nematode species. A positive correlation was demonstrated between numbers of viable juveniles in cysts and the amount of DNA that could be extracted from them. An internal control template was subsequently used in competitive PCR reactions with G. rostochiensis DNA and was shown to co-amplify with the nematode template. The resulting PCR product ratio allowed assessments of the levels of G. rostochiensis DNA extracted from cyst samples.