The aim of the present study is to investigate the effect of three entomopathogenic fungi (EPF) (Beauveria bassiana, Cladosporium cladosporioides, and Verticillium alfalfae) on the aphid species, Metopolophium dirhodum (Walker) (Hemiptera: Aphididae). The selected EPF were isolated from the agricultural soil of the National Institute of Plant Protection (INPV) in Constantine, Algeria, and were tested against the aphid insects that were collected from the same area. The aphid species M. dirhodum were exposed to each fungal spore suspensions 10 7 conidia/ml for 10 s. Percent mortality was recorded at 1, 3, 5, and 7 days post treatment. Percentage mortalities, 7 days post treatment, were 95.83, 63.98, and 51.83% by B. bassiana, C. cladosporioides, and V. alfalfae, respectively. The higher protease activities were observed for isolate V. alfalfae with 95 U/ml, followed by B. bassiana with 38.26 U/ml, and finally C. cladosporioides with 35, 65 U/ml. The results presented in this study revealed that there was no relation between high alkaline protease activities and high virulence isolates.

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