The results of experimental investigation of physical methods are presented for suppressing of biological activity of grain and grain product pests: harmful insects at each developmental stage except eggs (Insecta), mites (Arachnida, Acariformes) and microscopic fungi and bacteria. The technologies under development for disinfestation and disinfection of grain are based on irradiation of grain by modulated pulses of high-frequency (HF) electromagnetic fields and on simultaneous action of a complex of factors: vacuum and HF-field induced plasma. The threshold value of the electric field intensity for total insect mortality was found to be E = 4.0-5.0 kV/cm in the pulse mode at the base frequency of 47.5 MHz. When the combined technology is used, conditions are created in the irradiation chamber for HF-discharge and plasma formation, which are very strong factors influencing the biological organisms. These raise the energy (and cost) efficiency (approximately $2-3 per tonne of grain) of the combined technology for destruction of grain pests with complete environmental safety.