Occurrence of entomopathogenic fungi in forest soils in Poland

The study aimed to assess the occurrence of entomopathogenic fungi in forest soils, thereby evaluating one soil microenvironmental factor that contributes to resistance to insect pests that overwinter in the soil. Soils from coniferous, mixed and deciduous stands located in 54 forest districts were analysed. The trapping method used Tenebrio molitor larvae as traps. Entomopathogenic fungi occurred in 39% of the samples. In each case, extensive T. molitor larval infestation and rapid mortality were observed. In most cases (97%), only one entomopathogen species was present in the soil. There were identified Beauveria bassiana, B. caledonica, Cordyceps farinosa, C. fumosorosea, Lecanicillium lecanii, and Metarhizium anisopliae. It has been shown that forest soils are a habitat for entomopathogenic fungi, although their presence is uneven and species−diverse. T. molitor larvae are suitable for use as so−called ‘trap insects’ used to obtain entomopathogenic fungi.