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

Abstract

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.