TABLE CONTENTS

Impact of Temperature on Population Dynamics of Bursaphelenchus
xylophilus in European Conifer Saplings
Daub, M. (1), T. Schröder (2) & R.A. Sikora (3)
(1) Julius Kuehn-Institute, Federal Research Centre for Cultivated Plants, Institute for Plant Protection in Field
Crops and Grassland, Dürener Str. 71, D-50189 Elsdorf, Germany; (2) Julius Kuehn-Institute, Federal Research
Centre for Cultivated Plants, Institute for National and International Plant Health, Messeweg 11/12, D-38104
Braunschweig, German; (3) Institute of Crop Science and Resource Conservation (INRES), Phytomedicine –
Phytopathology & Nematology in Soil Ecosystems, Nussallee 9 53115 Bonn, Germany
Temperature has a significant effect on the development of Pine Wilt Disease (PWD) in trees
infested with B. xylophilus. It is known that increasing temperature enhances the development
of all life stages of the nematode in vitro. The effect of temperature on the population
dynamics of B. xylophilus and on PWD development in Pinus sylvestris, Larix decidua and
Picea abies was studied by inoculating four to five year old saplings with 4800 nematodes.
Nematodes were initially isolated from naturally infested Pinus pinaster and reared on
Botrytis cinerea. Experiments were carried out in climate chambers at 15, 20 and 25°C.
Nematodes were extracted from shoots and roots at seven sampling dates over a 61 day
period to cover the period of infection, nematode establishment and development and
pathogenesis of the plants. Temperature had a mayor affect on the population dynamics of
B. xylophilus in the susceptible P. sylvestris and L. decidua tree species. Temperature did not
significantly influence the pathogenicity of B. xylophilus, with maximum mortality in P.
sylvestris and L. decidua reached at temperatures exceeding 20°C. Wilt symptoms were not
detected at 15°C in any conifer species. At 20°C the maximum population density in shoots
of susceptible tree species was approximately 2500 nematodes per gram dry matter.
Nematode populations increased to approximately 4000 nematodes in P. sylvestris and in L.
decidua to 2700 nematodes per gram dry matter in shoots at 25°C. It was shown that wilt was
induced in P. sylvestris and L. decidua before nematodes reached a density of 1000
nematodes per gram dry matter.
Pyrosequencing for Analysis of Nematode Diversity
Porazinska, D.L. (1), R.M. Giblin-Davis (1), T.O. Powers (2), W. Farmerie (3), L. Faller (4),
N. Kanzaki (5), K. Morris (4), W. Sung (4) & W.K. Thomasm (4)
(1) Fort Lauderdale Research and Education Center, University of Florida; (2) Department of Plant Pathology,
University of Nebraska-Lincoln; (3) Interdisciplinary Center for Biotechnology Research, University of Florida;
(4) Hubbard Center for Genome Studies, University of New Hampshire; (5) Forest Pathology Laboratory,
FFPRI Japan
It is well established that nematodes play an important role in ecosystem processes, yet the
relevance of nematode species diversity to ecosystem ecology is still an enigma. Because
nematode identification of all individuals at the species level using standard techniques is
difficult, laborious, and extremely time consuming, the characterization of nematode
communities continues to be resolved at higher than the species level leaving ecological
analysis partially ambiguous or superficial. Novel cloning-independent pyrosequencing may
offer a potentially rapid tool to inventory nematode fauna at previously unparalleled levels of
resolution at faster speeds and lower cost. The main objective of our study was to assess the
suitability of 454 GS FLX technology for nematode species identification from metagenomic
samples.
5 th International Congress of Nematology, 2008 266