Effects of Beauveria bassiana on virulence and cellular morphology of hemocytes of Ostrinia furnacalis

Objective To test the effect of Beauveria bassiana on SYSU-OfHe-C, a cell line from hemocytes of Ostrinia furnacalis. To provide a theory basis for application of B.bassiana in the prevention and treatment of O.furnacalis.

Method MTT and CCK-8 were employed to test the virulence of B.bassiana on SYSU-OfHe-C.Optical microscope and scanning electron microscope were used to observe the growth of B.bassiana and its influence on the morphology of SYSU-OfHe-C cells.

Result The IC₅₀ values of B.bassiana against SYSU-OfHe-C cells at 24 hours after treatment were recorded as 2.8×10⁵ and 1.4×10⁵ mL^-1 respectively by MTT and CCK-8.Furthermore, under real-time monitoring with optical microscope, encapsulization and phagocytosis were not found and B.bassiana was highly competitive when the conidia of B.bassiana were inoculated in the culture of SYSU-OfHe-C cells at logarithmic stage reaching a final concentration of 3.5×10⁴ mL^-1 for B.bassiana.B.bassiana started to germinate at 10 hours after treatment, and meanwhile, SYSU-OfHe-C cells started to reduce in number and change in morphology.At 24 hours after treatment, B.bassiana grew the entire visual field.The nearly round SYSU-OfHe-C cells had elongated or turned into irregular shape.Aggregation, fragmentation, cavitation, protuberance and penetration of SYSU-OfHe-C cells caused by B.bassiana mycelia were observed.

Conclusion B.bassiana can change cellular morphology of hemocytes of O.furnacalis, but cannot induce its immune responses.