Abstract Polygraphus proximus Blandford (Coleoptera: Scolytidae), a non-aggressive phloephagous bark beetle that feeds on Far Eastern fir species, is the main species responsible for the rapid and widespread destruction of natural Abies sibirica forests, and has caused the mass mortality of planted Abies veitchii trees in Japan. It is unclear how long the attacks continue or whether the beetles progress to larger-diameter trees as their attacks progress. Thus, we investigated P. proximus attacks on A. veitchii and the association between tree mortality and trunk diameter over 6 years in Japan. Trees were severely attacked, and the proportion of infested trees significantly increased over 6 years. Small-diameter trees were attacked significantly more severely than large-diameter trees, and the beetles attacked larger-diameter trees in year 6. Despite this increase, larger-diameter trees were better able to survive attack. These results suggest that the beetles initially attack smaller-diameter trees in the early phase of mass mortality and then gradually attack larger-diameter trees as the infestation advances, but that the larger-diameter trees better survive the infestation. Enhanced colonization of smaller-diameter trees by P. proximus may act as a trigger for mass mortality and result in higher tree mortality; however, larger-diameter trees might regenerate A. veitchii forests after mass mortality.

中文翻译：

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树干直径影响 Polygraphus proximus 的攻击和随后的 Abies veitchii 的死亡率

摘要 Polygraphus proximus Blandford (Coleoptera: Scolytidae) 是一种以远东冷杉物种为食的非攻击性食腐树皮甲虫，是造成西伯利亚冷杉天然森林迅速和广泛破坏的主要物种，并导致大量种植日本的冷杉树。目前尚不清楚攻击会持续多久，或者随着攻击的进行，甲虫是否会发展成更大直径的树木。因此，我们调查了日本近 6 年对 A. veitchii 的 P. proximus 攻击以及树木死亡率与树干直径之间的关联。树木受到严重侵袭，受害树木的比例在 6 年内显着增加。小直径树木受到的攻击明显比大直径树木严重，甲虫在第 6 年攻击大直径树木。尽管有所增加，但直径较大的树木更能抵御攻击。这些结果表明，甲虫在大规模死亡的早期阶段最初攻击较小直径的树木，然后随着感染的进展逐渐攻击较大直径的树木，但较大直径的树木在感染后能更好地存活下来。P. proximus 对较小直径树木的增强定植可能会引发大规模死亡并导致更高的树木死亡率；然而，较大直径的树木可能会在大规模死亡后再生 A. veitchii 森林。但直径较大的树木能更好地抵御虫害。P. proximus 对较小直径树木的增强定植可能会引发大规模死亡并导致更高的树木死亡率；然而，较大直径的树木可能会在大规模死亡后再生 A. veitchii 森林。但直径较大的树木能更好地抵御虫害。P. proximus 对较小直径树木的增强定植可能会引发大规模死亡并导致更高的树木死亡率；然而，较大直径的树木可能会在大规模死亡后再生 A. veitchii 森林。