Biocontrol of eyespot disease on two winter wheat cultivars by an anecic earthworm (Lumbricus terrestris)

• The presence of anecic earthworms resulted in a smaller proportion of plants affected by eyespot.
• The presence of earthworms also decreased disease severity on wheat plants.
• Earthworms also modified resources allocation between plant organs and nutrient translocation inside the plant.
• Our results show that earthworm could be an effective biocontrol agent of eyespot.

Eyespot is a major fungal disease of winter wheat, mostly affecting the base of the stem. The development of biological control approaches, using organisms such as earthworms, represents a potential alternative strategy for eyespot control. In a greenhouse experiment, we analyzed the response of two wheat cultivars (Soissons and Aubusson) to the presence of the pathogenic fungus Oculimacula yallundae and the anecic earthworm Lumbricus terrestris, alone and in combination. We assessed necrosis frequency, necrosis severity, wheat biomass, resource allocation and soil mineral concentrations. Disease incidence was lower in the presence of earthworms: the frequency of necrosis was 44% lower for Soissons and 70% lower for Aubusson. Necrosis severity was also lower for both cultivars (50% lower for Soissons and 80% lower for Aubusson) in the presence of earthworms. Earthworms had no detectable effect on the shoot and root biomasses of plants exposed to the fungus, but they modified resource allocation between plant organs and nutrient translocation within the plant. Our results suggest that earthworms are a potentially effective biocontrol agent for eyespot, and we discuss the possible underlying mechanisms.