Distribution of insect pathogenic soil fungi in Switzerland with special reference to Beauveria brongniartii and Metharhizium anisopliae

Between 1998 and 2000 soil samples from 82 fields in north, east, central and south west of Switzerland were analysed for presence of insect pathogenic soil fungi using a selective medium and the Galleria bait method. The detection rates with either method were very similar. 96% of the fields distributed over all examined regions contained Metarhizium anisopliae. The presence of Beauveria brongniartii was limited to sites colonised by its host, Melolontha melolontha. It was also present at a site where M. melolontha disappeared about 40 years ago. On the other hand, B. brongniartii was not found in four fields containing M. melolontha populations. Beauveria bassiana, Paecilomyces fumosoroseus and Conidiobolus sp. were other entomopathogenic fungi isolated during this survey. Differences in the presence of M. anisopliae between arable fields and adjacent meadows as well as between orchards and meadows are discussed.