Beauveria bassiana on overwintering adults of Stereonychus fraxini in Croatia

Abstract: The ash weevil, Stereonychus fraxini, occurred in high infestation levels in 2009causing serious damage on different ash species in lowland forests in Lipovljani, Croatia.Overwintering adults in moos on the bottom of trees showed high mortality rates (over 80%).Most of these beetles were infected with the fungus Beauveria bassiana, which reduced thepopulation density of adults by 53.7%. The naturally occurring strain was isolated and tested onoverwintering individuals under laboratory conditions. Laboratory experiments demonstrated thatthis strain was very virulent on adult weevils. Due to restrictions in use of insecticides in Croatianforests, biological control using B. bassiana, is a promising option.