Entomopathogenicity of Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorokin isolated from different sources in the control of Rhynchophorus ferrugineus (Olivier) (Coleoptera Curculionidae)

Abstract

The entomopathogenicity of an indigenous Beauveria bassiana strain isolated from soil and of B. bassiana and Metarhizium anisopliae strains isolated in Italy from naturally infected Rhynchophorus ferrugineus (RPW) adults, was tested against larvae and adults of RPW in laboratory bioassays. The individuals were infected via direct contact on sporulated mycelia grown on Sabouraud Dextrose Agar or on wheat substrata. M. anisopliae obtained from R. ferrugineus showed the highest efficacy against RPW larvae and adults particularly against individuals contaminated on sporulated wheat, which showed values of cumulative larval mortality of 100% and adult mortality of 90%; LT50 was obtained in 13.1 days in both larvae and adults. B. bassiana strain isolated from soil recorded a lower cumulative mortality on larvae (13%) and adults (13%) treated on inoculated Sabouraud Dextrose Agar. B. bassiana strain isolated from RPW showed cumulative mortality values higher than 50% against larvae treated on inoculated wheat (55%) and Sabouraud Dextrose Agar (53%); LT50 was obtained in 15 days and 21.8.days respectively. Results are discussed with regard to the potential employment of the virulent indigenous strain of M. anisopliae for microbiological control of R. ferrugineus as part of an integrated pest management program