Can Beauveria bassiana reduce the root lesion nematode, Pratylenchus thornei, infection on wheat?

Abstract Background Limited number of control methods against root-lesion nematodes has increased the search for alternative management strategies. Due to secondary metabolites such as toxins and enzymes secreted by the entomopathogenic fungus, Beauveria bassiana, the number of studies on nematicidal potentials on many plant parasitic nematodes has increased. Almost no work was done on the nematicidal activity of B. bassiana, which is widely used as a bio-insecticide, on the root lesion nematode, Pratylenchus thornei, commonly found on wheat in Turkey. In the present study, it was aimed to determine the pathogenicity of two native B. bassiana isolates (BIM-001 and BY2) obtained from Turkey against P. thornei on wheat under controlled conditions. Results Spore suspension of B. bassiana isolates affected P. thornei soil, root, final nematode density and reproduction rate at different degrees according to spore concentration. The soil, root, total nematode density, and reproduction rate in the control on İkizce cv. were 1234.0 adult + larvae/500 g soil, 1105.0 adult + larvae/per pot, 2341.0 (soil + root density) and 5.8 (PF(final nematode density/PI (initial inoculum density)), respectively. It was determined that these parameter values were at the lowest at 108 spore/ml than other concentrations in both isolates of B. bassiana. In 108 spore/ml concentrations of BIM-001 isolate, while P. thornei soil, root, total nematode density, and reproduction rate on İkizce were 641.7 adult + larvae/500 g soil, 930.9 adult + larvae/per pot, 1572.6 (soil + root density) and 3.9 (PF/PI), respectively, these parameter values were found to be 645.2 adult + larvae/500 g soil, 849.0 adult + larvae/per pot, 1492.2 (soil + root density) and 3.6 (PF/PI) at 108 spore/ml concentrations of BY2 isolate. It was observed that the reproduction rate of P. thornei decreased at 108 spore/ml concentration of BIM-001 and BY2 isolates compared to the control. Conclusion Native B. bassiana isolates of BIM-001 and BY2 reduced P. thornei on wheat and the concentration was important for the pathogenicity of B. bassiana. While the reproduction rate of P. thornei at 108 and 107 spores/ml concentrations in both isolates decreased than the control. At 106 spore/ml concentration it was found similar to the control. Even though B. bassiana is known as an effective biocontrol agent against insects and some plant-parasitic nematodes, more detailed studies should be done on its effect on P. thornei.