Efficacy of Beauveria bassiana¹ and Metarhizium anisopliae ¹ to control pieris rapae² on cabbage in the field

The efficacies of a Beauveria bassiana (Bals.-Criv.) Vuill. native strain (BbPM) and B. bassiana (Bea-Sin™) and Metarhizium anisopliae (Metchnikoff) Sorokin (Meta-Sin™)-based commercial products were evaluated against the imported cabbageworm, Pieris rapae (L). Three concentrations (1.2×10 ¹², 1.2×10⁹, and 1.2×10⁶ conidia per hectare) of BbPM, Bea-Sin™, and Meta-Sin™ were applied to commercial cabbage, Brassica oleracea var. capitata L., to evaluate larval mortality during 2005 and 2006. Sampling was done weekly during a 28-day period. Native strain BbPM (92.7%) and Bea-Sin™ (91.8%) killed significantly more larvae than did Meta-Sin™ (62.6%) during both years. The bioinsecticides were most effective early (on sampling days 7 and 14). In general, viability of B. bassiana conidia ranged between 90 and 93% while that of Meta-Sin™ was 52%. The native strain BbPM provided similar control as Bea-Sin™, and both killed significantly more imported cabbageworm larvae than did Meta-Sin™.