Virulence of Some Selected Fungal Isolates against the Cotton Leafworm, Spodoptera littoralis (Lepidoptera: Noctuidae)

The present study was carried out to investigate the virulence of two fungal isolates against cotton leafworm Spodoptera littoralis. Six fungal isolates were isolated from a soil sample. Only two isolates were identified as Cunninghamella sp. and Rhizopus sp < /em>. according to the data of preliminary test where they cause higher mortalities. The highest mortality was recorded by isolate Rhizopus sp < /em>. In addition, the same isolate recorded the lowest LC50 values, 2.16x107 conidial concentration/ml. The fungal isolates exhibited an insignificant decrease in the weight of treated larvae. Larval duration was decreased insignificantly at all conidial concentration except the highest conidial concentration that insignificantly increased it. Pupation and adult emergence % were affected. Adult deformities were appeared only bythe isolate, Cunninghamella sp.. However, the isolate Rhizopus sp < /em>. exhibited the highest proteolytic and lipolytic activity than isolate Cunninghamella sp. while the highest chitinolytic activity was recorded by the isolate Cunninghamella sp < /em>