Adhesion and virulence of conidia of Metarhizium anisopliae to Thrips palmi (Thysanoptera: Thripidae)

Abstract

Two isolates of Metarhizium anisopliae were selected based on virulence in order to clarify the relationships between adhesion and virulence of conidia to Thrips palmi. LC50 values (CFUs/ml) of M. anisopliae UZ and OE-2 to adults of T. palmi were 7.5×105 and 2.5×105, respectively. The conidia of M. anisopliae OE-2 bound to the adult cuticles more effectively than conidia of M. anisopliae UZ. This suggests that the virulence of M. anisopliae to T. palmi is correlated with the number of adhereded conidia. The conidial detachment value, conidial germination ratio on the adults and LD50 values (number of conidia/adult) were also compared between the two isolates. These experiments also demonstrated that conidial development after adhesion affected the virulence of M. anisoplae to T. palmi.