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Nematode protection mechanisms to be elucidated

Certain nematodes cause great damage to crops and can be difficult to control. An improved understanding of nematodes' modes of action can contribute to developing efficient methods of control.

2019.06.28 | Janne Hansen

Nematodes can cause great harm to crops, such as this rootknot on the roots of a carrot. Photo: Mette Vestergård

Nematodes can be both beneficial and harmful. They are beneficial in that they help decompose dead plants and animals in the soil, and kill certain plant-pathogenic insects. However, nematodes also have a dark side: They cause 10 percent of crop losses globally. Nematodes that attack plant roots are particularly problematic. 

Now researchers from the Department of Agroecology at Aarhus University will delve into nematode larvaes’ secrets to see if they can find efficient, environmentally friendly control methods. This will be done in a new project that has been granted 2.9 million kroner from the Independent Research Fund Denmark.  

One way to control the undesired nematodes is to treat their larvae with microorganisms that are harmful to the nematode larvae. This strategy has not met undivided success. However, the soil environment can be rough for young larvae, so how do they manage to survive? 

The researchers’ hypothesis is that the answer can be found in the special combination of microorganisms – the so-called microbiome – that lives on the cuticle of the larvae. 

The nematodes that the researchers are investigating spend most of their life cycle within the plant roots, except during a single larval stage, J2, during which they live freely in the soil. This J2 larva moves around in the soil and infects plants despite the fact that the environment, which includes a range of pathogenic bacteria, is very tough for the young larva. 

A shield of microorganisms for protection

The researchers theorise that nematode larvae have a microbiome on their cuticle that protects them from attacks from soil pathogenic microorganisms. 

- We want to investigate if there are specific key microorganisms on the surface of the nematodes that are independent of the soil that the larvae live in, and whether this microbiome protects the larvae or even helps them infect plant roots. We also want to investigate if this protection is reduced in soil environments with poor biological diversity, explains the leader of the new project, researcher Mette Vestergård from the Department of Agroecology. 

The researchers will use the Northern rootknot nematode as their research object. This is a nematode that attacks a very wide range of crops in greenhouses and fields all over the world. The aim is to find out which microorganisms play a key role in the larvaes’ survival and ability to infect plants, and if conditions in the soil can be controlled to minimise the problem. 

- Identification of J2-protective organisms can provide us with the specific knowledge that is needed to underpin new research in soil management strategies that aim to reduce the occurrence of these protective microorganisms and thereby promote the efficiency of biological control methods, says Mette Vestergård.    


For more information please contact

Researcher Mette Vestergård, Department of Agroecology, email: mvestergard@agro.au.dk, telephone: +45 8715 8121

Agro, Crops, DCA