White rice and pearled barley mass cultured Beauveria bassiana and its pathogenicity toward Choristoneura fumiferana

Abstract

An assay screening five isolates of the entomopathogenic fungus Beauveria bassiana from various geographic and host origins, found the following strains most pathogenic toward 4th, 5th and 6th instars of Eastern Spruce Budworm (ESB): 1756 (sawfly larva, Nova Scotia); ARSEF1850 (Western Spruce Budworm larva, British Columbia); and DAOM196480 (ESB larva, N.B.). The ARSEF and DAOM strains were mass cultured on long grain white rice and pearled barley, and the pathogenicity of the resultant product towards 6th instars of ESB larvae was assessed in a bioassay. ARSEF out-performed DAOM in the mass culture trials, and white rice and barley were suitable production substrates. With the exception of one inoculum that consistently caused lower mortality, efficacy of the commercial product BotaniGard (GHA strain)-a positive control in the bioassay, and the barley, rice, and agar grown isolates toward ESB, was similar. The GHA strain and agar grown isolates demonstrated slightly higher virulence however.