TABLE CONTENTS

Pratylenchus and Radolpholus: Ecological and Evolutionary Relationships
Based on Morphology, Genetics, Host and Life History Characteristics
Hodda, M. (1), V.A. Vanstone (2) & J.M. Nobbs (3)
(1) CSIRO Entomology, GPO Box 1700 Canberra, ACT 2601, Australia; (2) Department of Agriculture and
Food Western Australia, South Perth, Western Australia 6151;(3) Plant and Soil Health, South
Australian Research and Development Institute, South Australia 5001
The nematode genera Pratylenchus and Radopholus are, by any measures, closely-related in
terms of evolution and ecology, with both traditionally classified in the same family, and both
living as migratory internal root parasites. However, there are considerable differences in
some characteristics, such as in life where sexual dimorphism occurs in Radopholus but not
Pratylenchus, in the development of the reproductive system in to be didelphic in
Radopholus, but prodelphic in Pratylenchus, and in the dorso-ventral position of the
oesophageal glands. Furthermore, there are many species of Radopholus in Australia, but
only one apparently native Pratylenchus species. In terms of genetics, the two genera
evolved separately in according to a large-scale analysis of a few representatives of each
genus within the entire suborder Tylenchina. More detailed analyses of the same gene, but in
many more populations and species within each genus suggests that the two genera evolved
closely with each other. In terms of hosts, both have wide host ranges, but there are some
differences between genera. What is going on? Barring some form of reticulate evolution,
not all lines of evidence can be correct.
In this presentation, all lines of evidence are evaluated, and the relationships between the two
genera clarified. The implications of these evolutionary relationships for attempts to manage
the damaging pests in both genera are discussed.
5 th International Congress of Nematology, 2008 184