Beauveria bassiana (Bais.) Vuill. isolated from some lepidopterous species in Japan

Identification were undertaken on 17 isolates of the insect pathogenic fungi isolated respectively from the naturally infected larvae of 8 lepidopterous species. In the slide-culture tests, 9 isolates were identified as Beauveria bassiana, and the remaining isolates were species of the following genera: Isaria, Spicaria, Metarrhizium, and Hirsutella. B. bassiana were isolated from the following insect species: Dioryctria splendidella, Dendrolimus spectabilis, Phassus excsescens, and Euproctis pseudoconspersa. These representatives identified in the present investigation were compared with the cultures of B. bassiana isolated from white muscardine larvae of Bombyx mori. On artificial media and on killed pupae of Bombyx mori most isolates of the B. bassiana representatives were characterized by producing flat, mealy, pulverulent growth, whereas the remaining isolates formed elevated, cottony, floccose growth. All of them, however, produced pale yellow spore masses, while the cultures isolated from Bombyx mori produced white spore masses. In isolates from the above wild insects, sporogenous cells generally occurred on the globose vesicles, on the conidiophores, and directly on the mycelium within the typical Beauveria clusters. These varied from globose to cylindrical shapes. On the other hand, the hypha-like sporogenous cells occurred singly on the mycelium in isolates from Bombyx mori.