Comparative virulence of <i>Beauveria bassiana</i> isolates against clover root weevil (<i>Sitona obsoletus</i>)

Abstract

Clover root weevil (Sitona obsoletus) (CRW) is of Palearctic origin and in New Zealand has become an invasive pest of white clover A major survey was undertaken in 2000 to identify and collect the most promising CRW biocontrol agents from a wide range of locations in Europe and the UK Subsequently several Beauveria bassiana strains obtained from the cadavers of weevils originally collected live from England Wales France and Romania were isolated in containment at AgResearch Lincoln Thereafter bioassays using New Zealand fieldcollected CRW populations showed that all the European isolates were virulent against the adults with two being particularly effective Notably all of the European B bassiana isolates exhibited greater virulence against CRW than a New Zealand isolate collected from local CRW populations and a commercial B bassiana product registered in the USA as Botanigardreg;