Distribution of the four-eyed fir bark beetle (Polygraphus proximus Blandford) in forest stands of the Sverdlovsk region

   The fir four-eyed bark beetle (Polygraphus proximus Blandford, 1894) (Coleoptera, Curculionidae: Scolytinae) was unknown in the Sverdlovsk Region till 2023. The portion of Siberian fir in the forest stands in the Sverdlovsk region is insignificant, the area occupied by fir is about 175 thousand hectares or 1.4 % of the area of the main forest-forming species of the region (2.4 % of the coniferous area). The main part of fir stands is concentrated in the western part of the region where the main specially protected natural territories of the region are located: the Visimsky Nature Reserve, the «Denezhkin Kamen» Nature Reserve, the Natural Park «Olenyi Ruchyi» and the Natural Park «Reka Chusovaya».

   The purpose of the study is to identify the spreading of bark beetle the Sverdlovsk region, to assess the plant damage and the rate of development of foci in areas with high density of this species.

   As a result of examination conducted during 2023–2024, the bark beetle was found in a significant area of fir stands in the western part of the Sverdlovsk region. In the north of the region, damage to plantings by invaders has been found up to the city of Serov (59° 35' N). In the northern regions, the species density is currently relatively low. Significant foci of outbreak are forming in the southwestern part of the region. The Rosselkhoznadzor has currently established three quarantine zones in this area with a total area of 10,655 hectares. An analysis of the rate of development of foci of outbreak in the «Olenyi Ruchyi» Nature Park showed that in some areas by the autumn of 2024, up to 50 % of the trees had either already dieback or were inhabited by the invader. It is not clear yet how far the bark beetle will spread to the north of the region. To predict the possible limits of the range expansion (primarily the northern ones), it is necessary to clarify the phenological characteristics of this species in the Sverdlovsk region.

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