Virulence of Metarhizium brunneum to Field Collected Agriotes spp. Wireworms

The number of active substances registered for wireworm control is decreasing. Consequently, inventorization programs were launched to find and identify potential wireworm biological control agents. Metarhizium brunneum Petch was isolated from an adult Agriotes sp. (Coleoptera: Elateridae) in Slovenia. The strain belongs to a phylogenetic lineage of M. brunneum accommodating isolates from Asia and North America while it was reported from Europe (Denmark and Switzerland) only recently, and for the first time in Slovenia. Its pathogenicity to field-collected Agriotes spp. was tested in feeding and soil experiments. The latter lasted either 15 or 90 days and adopted different concentrations of fungal conidia. Coating potato slices with conidia had no effect on mortality. However, M. brunneum in soil significantly increased wireworm mortality in short- and long-term bioassays. The average LT50 based on Probit analysis was 44.6 days for the M. brunneum treated wireworms and 741 days for the negative controls.