Ecological Balance in Unmanaged Beech Reserves: Scolytids or Their Natural Saproxylic Beetle Enemies?

The accumulation of dead wood can serve as a potential source of insect pests, with scolytids being the most frequently discussed group. The aim of this study was to quantify the abundance and species composition of scolytids and their natural saproxylic beetle enemies in a beech reserve. In addition, we compared the types of dead wood preferred by scolytids and their natural enemies. Beetles were sampled passively using window traps, which effectively capture the actual density of beetles within the stand. In total, 20,515 saproxylic beetles were collected; the analyses included 11 scolytids species with 3017 individuals and 51 species of natural enemies with 4976 individuals. The results revealed a significantly higher abundance of natural saproxylic beetle enemies, with no strong affiliation to specific types of dead wood. This may indicate a high mobility of natural enemies actively searching for food resources within the forest stands. In conclusion, beech reserves support high abundances of natural scolytid enemies that exceed the numbers of scolytids themselves, indicating effective natural control processes.