EN
Experiments done and presented below aimed at proving that applied species and Polish strains of entomopathogenic nematodes (EPNs) can be used to reduce the number of Melolontha melolontha. Invasive larvae of Steinernema arenarium Bys, S. arenarium Lub, S. feltiae Rap, Heterorhabditis bacteriophora Sie, H. megidis Pla, H. megidis Lub i H. megidis Pla, H. megidis C3 were used in the experiments as biocontrol agents against the larvae L1, L2 and L3 of M. melolontha. The experiments were done at 20°C, in 25 ml boxes filled with pasteurized (3 h at 70°) and air-dried soil. Pathogen doses were 100 IJ/insect. The result showed that susceptibility of M. melolontha to EPNs depends on the insect's developmental stage. Larvae L1 were the most susceptible. S. arenarium Bys and H. megidis strains were more effective in infecting M. melolontha larvae than S. feltiae Rap and H. bacteriohora Sie.