Abstract: The infection process of Beauveria bassiana conidia on cuticle of Solenopsis invicta was observed using scanning electron microscope (SEM). The results showed that most of conidia were deposited on intersegmental membranes, folded regions on thorax, spiracles, cavities, setae and coxae of legs. The germinated conidia mainly invaded the worker cuticle from intersegmental membranes, as well as setae, cuticle cavities, rugous regions on cuticle and tibiae. The conidia adhered on worker surface began to germinate at 12 h after inoculation. The first penetration of germinated conidia occurred in intersegmental membrane at 18 h after inoculation, followed by penetration of conidia around setae at 24 h after inoculation. Conidia on all kinds of surface topography including the thorax, abdomen and legs successfully invaded into the cuticle and resulted in infection at 60 h after inoculation. The germinated conidia of the isolate either invaded the cuticle directly with germ tube or invaded the cuticle by producing appressorium during the course of infection.

Key words: Solenopsis invicta, Beauveria bassiana, conidia, infection process, scanning electron microscope