Thesis subject

Stress-induced changes in nematode communities

Molecular ecology avant la lettre.

Nematodes constitute a diverse group within the soil fauna, feeding on bacteria, fungi, other nematodes and plant-roots. This intimate feeding relationship with all major players in the soil
makes that mild → severe stresses (ploughing, manuring, use agro-chemicals, inundation, deposition of e.g. heavy metals, PCBs or urban waste) induces defined changes in the nematode community. Actually, the composition of nematode communities is highly indicative for the soil health condition; it allows to pinpoint the biological impact of soil disturbance as well as recovery.        
Recently, we’ve set up a molecular framework for nematode detection (and evolution) based on small and large subunit ribosomal DNA sequences. This framework includes virtually all groups of terrestrial and aquatic nematodes present in NW Europe.

The availability of a DNA-based community analysis tool allows to find answers on the following questions:

  • Does the use of a given genetically modified (GM) plants have an effect on soil life?
  • What is happening below-ground when we take areas out of production, how soon soil life will recover?
  • What is happening to soil life upon a switch from conventional to organic farming?
  • What does the composition of the nematode communities tell us about soil suppressiveness against pathogens (bacteria, fungi or nematodes)?   

Some of these subjects include season dependent field work and should be done preferably in Spring – Summer time. This research is done in cooperation with other laboratories and companies within and outside Wageningen UR.