Biological control of the European cockchafer: persistence of Beauveria brongniartii after long-term applications in the Euroregion Tyrol

Melocont^® Pilzgerste, a commercial product based on the entomopathogenic fungus Beauveria brongniartii (Sacc.) Petch (Ascomycota: Hypocreales) strain BIPESCO 2, was applied at different rates and time points over a period of 24 years in East-, North- and South Tyrol (Austria and Italy) to control the European cockchafer (Melolontha melolontha L. and M. hippocastani F.). Beauveria spp. density was assessed and Beauveria spp. isolates were characterized at species and genotype level using Bloc intergenic region sequence and simple sequence repeat marker analyses. BIPESCO 2 was detected at 41 % of the treated sites, predominantly at sites where the fungus was applied at least once during the four years prior to sampling. At one site BIPESCO 2 was detected 15 years after the last treatment. Results showed that applications should be repeated to achieve good persistence of the biological control agent, and it indicated that despite intensive applications diverse populations of B. brongniartii or Beauveria spp. consortia can coexist in these habitats.