INVESTIGATIONS OF ENTOMOPHTHORA-MUSCAE (COHN) (ENTOMOPHTHORALES, ENTOMOPHTHORACEAE) CONIDIAL INFECTION ON HOUSEFLY MUSCA-DOMESTICA (LINN) BY SCANNING ELECTRON-MICROSCOPY

An entomogenous fungus, Entomophthora muscae, was studied morphologica lly with respect to the formation of primary and secondary conidia and germ tubes. The fungus penetrated the insect cuticle by germ tubes th at were produced at the base of each conidium that penetrated directly through the cuticle. Fungal germ-tube formation and penetration of ho st integument were observed. The tough germ-tube penetration point see med to provide abundant energy for the penetration of the host integum ent. Conidia not directly on the integument formed secondary conidia b ut were never observed to form germ tubes. Neither appressorium nor in fection cushion was observed on the germ tubes.