Overview of the Current Secondary Range of the Four-Eyed Fir Bark Beetle (Polygraphus proximus Blandford) in the Russian Federation

Current data on the existing secondary range of the four-eyed fir bark beetle Polygraphus proximus in Russia, a dangerous invasive pest of fir stands, are presented. The alien species was found on the territory of 18 administrative subjects of the Russian Federation, from Moscow and Moscow oblast in the west to the Irkutsk oblast and the Republic of Buryatia in the east. Within 17 years since the species was first found outside its Far Eastern natural range, it has spread widely in Western and Central Siberia and in recent years in the Pre-Urals region and the Urals, from the middle taiga to forest steppe on the plains to the upper limit of Siberian fir in the mountains. It forms outbreak foci in exploitative forests, in specially protected natural areas, and in artificial fir plantations of settlements. Taking into account the peculiarities of host plant growth, the time of detection, and sources of invasive population formation, the structure of secondary range is developed, and the characteristics of modern distribution of the four-eyed fir bark beetle and the forecast of further expansion of its secondary range are given.