Physiological concepts and bioassays of <i>Beauveria bassiana</i> and <i>Paecilomyces lilacinus</i> attacking the corn leaf aphid <i>Rhopalosiphum maidis</i> (Hemiptera:Aphididae) in Assiut, Egypt

Enzymatic activity and pathogenicity of Beauveria bassiana and Paecilomyces lilacinus against the corn leaf aphid Rhopalosiphum maidis (Fitch) (Hemiptera: Aphididae) were studied in the laboratory. The results showed that two isolates of B. bassiana and one isolate of P. lilacinus were found effective at all concentrations on R. maidis, but the uppermost concentration (2×107 conidia/ml) of P. lilacinus provided maximum mortality (100%). While B. bassiana isolate No. (1) and B. bassiana isolate No. (2) provide mortality rates of 85% and 95% at their highest concentrations of 1.8×107 and 1.30×107 , respectively. All isolates revealed enzymatic activity such as lipase, protease, and chitinase, but P. lilacinus showed the highest activity. B. bassiana (2) isolate was more aggressive than other isolates, as indicated by the low value of LC50 compared with other isolates.