ObjectiveThis paper aims to study the process of Clonostachys rosea infecting Cephalcia chuxiongica larvae, and provides a reference for the research on pathogenicity mechanism of Ce. chuxiongica.

MethodWe observed the ultrastructural changes of Ce. chuxiongica body wall infected by Cl. rosea SWFUYHL 02-03 using the scanning electronic microscopy (SEM) and transmission electron microscopy (TEM).

Result Based on the SEM observation, the conidias adhered onto spiracles and internode membranes of body wall after 6 hours inoculation. The germ tubes of this fungi penetrated into the cuticle of Ce. chuxiongica larvae after 14 hours. The conidia and hypha penetrated into the cuticle of Ce. chuxiongica larvae and the hypha began to multiply rapidly after 26 hours, and then the hypha penetrated out from the cuticle of Ce. chuxiongica larvae and generated sporogenous structure when it was inoculated at 72 hours. Meanwhile, inferred from the TEM observation, the participation of enzymes and histolysis could be found with the penetration process of hypha. The spores adhered onto the body wall of the Ce. chuxiongica larvae when it was inoculated at 6 hours and then the conidia germinated and penetrated into the secretion of cuticle after inoculation for 14 hours. The hypha penetrated and spreaded into the cuticle, and halos with low electron density could be observed around the penetrated hypha after 26 hours. The epidermis cell arranged loose and became vacuole after inoculation for 38 hours and the larvae's body was full of hypha, and a great deal of hypha were on the cuticle of Ce. chuxiongica larvae after inoculation for 48 hours.

ConclusionThe spores and hypha of Cl. rosea SWFUYHL 02-03 could parasitize and kill the Ce. chuxiongica larvae. The SEM and TEM observations accurately reflected the infection process of Cl. rosea SWFUYHL 02-03 on the larvae of Ce. chuxiongica, and proved the existence of enzymes and virulent metabolites.