TABLE CONTENTS

Nematode Diversity and Function in Dutch Sand Dunes
Brinkman, E.P., H. Duyts & W.H. Van der Putten
Netherlands Institute of Ecology (NIOO-KNAW), Centre for Terrestrial Ecology, P.O. Box 40, 6666 ZG
Heteren, The Netherlands
Dutch coastal sand dunes are dominated by Ammophila arenaria (marram grass) that is
planted to stabilize the sand surface. Yearly deposition of wind-blown sand from the beach
enables a temporary escape from plant-feeding nematodes and pathogens in the lower sand
layers, facilitating vigorous growth of the grass at the seaward side of the dunes.
Several endoparasitic and ectoparasitic plant-feeding nematodes are associated with various
dune grass species. Some are generalist and some are specialist feeders, however, specificity
is not always related to occurrence. For example, Meloidogyne duytsi multiplies on two
related grass species, but in the field occurs with only one of them.
The cyst nematode Heterodera arenaria migrates towards new root layers that are formed on
top of old root layers in response to sand burial. Part of the population remains behind, which
is disadvantageous for their own fitness. However, it provides insurance for the population
when, in extremely dry years, the emigrant nematodes fail to produce offspring.
Competition with other plant-feeding nematodes may regulate the density of a species that
otherwise would be harmful to the plant. In a field experiment with A. arenaria, M. maritima
added alone developed faster and to higher densities than concomitant addition of Heterodera
arenaria and Pratylenchus penetrans. Moreover, addition alone resulted in lower plant
biomass.
Interactions may lead to competition or facilitation, depending on host plant identity. We
added Tylenchorhynchus microphasmis and T. ventralis to A. arenaria (good host for both)
and Carex arenaria (good host for T. microphasmis only). Addition of T. ventralis did not
affect multiplication of T. microphasmis. However, on A. arenaria, T. ventralis experienced
interspecific competition, whereas on C. arenaria, T. microphasmis facilitated multiplication
of T. ventralis. Therefore, including nematode interactions may lead to different conclusions
on nematode population dynamics than focusing on each species alone.
5 th International Congress of Nematology, 2008 4