The potential threats posed by the invasive bark beetle Polygraphus proximus (Coleoptera, Curculionidae: Scolytinae) to a natural park in the Middle Urals (Russia)

Abstract

The four-eyed fir bark beetle Polygraphus proximus Blandford, 1894 (Coleoptera, Curculionidae: Scolytinae) is an invasive species that originates from the Far East. Since early 2000s, it became known as an aggressive pest causing massive dieback of Siberian fir (Abies sibirica Ledeb.) in Siberia and, to some extent, in the European part of Russia. Here, we report the first record of P. proximus in Sverdlovsk Region (the Middle Urals, Russia). In summer 2023, A. sibirica trees colonized by the pest were discovered on the territory of the “Olenyi Ruchyi” Natural Park. The dendrochronological analysis of the cores of fir trees killed by the beetle indicated that the majority (72%) of these trees died in 2021–2022, while the earliest tree death occured already in 2007 and 2009, meaning that the pest was present in the Natural Park for at least two decades. Mycological analysis of bark and wood samples of infested trees revealed the fungus colonies assigned to Grosmannia aoshimae (Ohtaka, Masuya & Yamaoka) Masuya & Yamaoka. Associated with P. proximus, this Far Eastern fungus species has spread with the beetle to Siberia and the Urals, contributing to tree mortality. Siberian fir is present on 69% of the forested area in the “Olenyi Ruchyi”. The colonization of fir trees by P. proximus recorded in the park in 2023 alarms about the high risk of the pest outbreak in the coming years, which may lead to subsequent tree death over a huge territory of the park affecting its ecological, cultural, and recreational values. To prevent the dramatic impact, it is highly urgent to take all the necessary measures to suppress the distribution and combat this alien pest.

Keywords

• xylophagous species
• alien pest
• fir forest stands
• tree mortality
• grosmannia aoshimae