Abstract: The infection mode of the diamondback moth, Plutella xylostella by two isolates of the entomopathogenic fungus Metarhizium anisopliae was studied using scanning electron microscopy.  The results indicated surface topography of host affected infection behavior, especially appressoria production. There were more appressoria formed and shorter germ tubes grew before penetrating in gentle and spinous surface topography than in acanthoid surface topography. The germ tubes of LF68 isolate were shorter than that of LD65 isolate before the appressoria formed  or penetration occurred in all kinds of surface topography. Conidia germinated within 7 h postinoculation for the two isolates, but penetrations were observed within 10 h and 13 h for LF68 and LD65 isolates, respectively.

Key words: Entomopathogenic fungus, Metarhizium anisopliae;Plutella xylostella, cuticle topography, invasion behavior, infection process, scanning electron microscopy