Efficacy of soil applications of Metarhizium anisopliae (Metsch.) Sorokin conidia, and standard and lyophilized mycelial particles against scarab grubs

Abstract

The efficacy of soil inoculations of Metarhizium anisopliae (Metsch.) Sorokin propagules against third-instar grubs of the Japanese beetle and European chafer was investigated in the laboratory. Inoculum consisted of conidia; standard (unlyophilized mycelial particles with size ranges of <125, 125–250, and 250–500 μm; and lyophilized mycelial particles with size ranges of 125–250 μm and 250–500 μm. Grub mortality occurred significantly quicker in mycelium-inoculated compared with conidia-inoculated soil. Total mortality, however, did not differ significantly between the two types of inoculum. Pathogen titers were consistently higher in soil inoculated with 250- to 500-μm-size compared to 125- to 250-μm-size particles. Lyophilization of mycelial particles did not significantly affect soil titers or pathogenicity in two of the three bioassays conducted.