Repeated in vitro subculturing alters spore surface properties and virulence of Metarhizium anisopliae.

Repeated subculturing caused rapid changes in the spore surface properties and virulence of Metarhizium anisopliae. Of the two strains evaluated, M. anisopliae V245 attenuated more rapidly than V275. Electrophoretic mobility and Radial Flow Chamber assays were used for the first time to generate qualitative and quantitative information on the adhesive forces of M. anisopliae conidia. Independent of strain, adhesion, hydrophobicity and spore-bound Pr1 declined after the first subculture; however, spore surface charge decline was erratic. Adhesion and hydrophobicity stabilized after the third subculture, whereas spore-bound Pr1 continues to decline following repeated subculturing. Decline in spore bound Pr1 was directly correlated with decline in virulence, however, such correlation with adhesion, hydrophobicity or surface charge could not be established. Because spore-bound Pr1 activities were directly correlated with M. anisopliae virulence; it could be used as a quality-control marker to monitor changes in virulence.