Biocontrol Potential of Some Entomopathogenic Fungal Strains Against Bean Aphid Megoura japonica (Matsumura)

This research reported the in vitro pathogenicity of Verticillium lecanii strains, L2 and L5, and Beauveria bassiana strains, B76 and B252, against Megoura japonica using leaf-dip method. The virulence potential of these four entomopathogenic fungal strains of V. lecanii and of B. bassiana were compared between fungi conidia (concentrations 1 × 106, 1 × 107, and 1 × 108 conidia mL−1) and culture filtrate. Moreover, binary combination of four different fungal strains (L2 + B76, B76 + L5, L2 + B252, and L2 + B76 + B252 + L5) were evaluated against M. japonica under control condition. Aphid mortality was recorded after two, four, six, and eight days of post-treatment. In the conidial concentration bioassay, strain B76 showed maximal mortality (85.3%) against bean aphid, and strain L5 showed the lowest effect (60.0%) at the highest concentration (1 × 108 conidia mL−1) at eight days post-treatment. Whereas, binary combinations of B76 and L2 strains showed the highest effect against M. japonica (90.5%) than other combinations. Moreover, in comparison with the effect of filtrate and conidia bioassay, 91.4% and 84.1% were achieved in strain B76, and the lowest effect (63.8% and 55.1%) was recorded in strain L5.