Potential of the fungal feeding nematode Aphelenchus avenae to control fungi and the plant parasitic nematode Ditylenchus destructor associated with garlic

Together with several fungi, the plant parasitic nematode Ditylenchus destructor is among the pathogens that cause serious damage to garlic production areas in Japan. Because D. destructor is a plant and fungal feeder, its infestation may be influenced by the garlic plant-associated fungi and suppressed through control of those fungi. However, no information is currently available regarding the interaction between the nematode and the fungi. Aphelenchus avenae is a non-parasitic fungivorous nematode, which can potentially control plant-pathogenic fungi. Assuming an interaction between the garlic-associated fungi and D. destructor, A. avenae may contribute to suppress D. destructor through fungal control. The present study investigated the interaction between the fungi isolated from garlic and D. destructor as well as the preference of D. destructor and A. avenae for those fungi, aiming to control the fungi and D. destructor using A. avenae. Most fungi isolated from garlic attracted both D. destructor and A. avenae, allowing their propagation. In vitro experiments involving the simultaneous inoculation of D. destructor and A. avenae on a fungus mat showed a better propagation of A. avenae than D. destructor on several fungi as well as the suppression of the D. destructor propagation rate. Similarly, pot experiments involving the simultaneous inoculation of A. avenae showed suppression of D. destructor propagation. The fact that D. destructor is attracted to, feeds on, and propagates on garlic-associated fungi suggests that those fungi can be a host for D. destructor, playing an important role for the nematode's infestation of garlic fields. Further, A. avenae propagation on the fungi and its ability to suppress the propagation of D. destructor suggest that A. avenae is a potential biological agent to control both the garlic-associated fungi and D. destructor.