Ploetz Randy C, Hulcr Jiri, Wingfield Michael J, de Beer Z Wilhelm
University of Florida, Tropical Research & Education Center, Homestead, FL 33031.
University of Florida, School of Conservation and Forest Resources, and USDA Forest Service, Gainesville, FL 32611.
Plant Dis. 2013 Jul;97(7):856-872. doi: 10.1094/PDIS-01-13-0056-FE.
Diseases associated with ambrosia and bark beetles comprise some of the most significant problems that have emerged on trees in the last century. They are caused by fungi in the Ophiostomatales, Microascales, and Hypocreales, and have vectors in the Scolytinae (ambrosia and bark beetles) and Platypodinae (ambrosia beetles) subfamilies of the Curculionidae (Coleoptera). Some of these problems, such as Dutch elm disease, have a long history, have been extensively researched, and are fairly well understood. In contrast, other similar diseases developed recently and are poorly or partially understood. The emergence and unexpected importance of these tree diseases are discussed in this article. An underlying factor in most of these interactions is the absence of a coevolved history between the so-called "naïve" or "new encounter" host trees and the pathogens and/or beetles. For the ambrosia beetles, these interactions are associated with susceptibility to what are typically benign fungi and atypical relationships with healthy trees (ambrosia beetles favor trees that are dead or stressed). Interestingly, the pathogens for both the ambrosia and bark beetle-associated diseases often have symbiotic relationships with the insects that are not based on phytopathogenicity. Some of the most alarming and damaging of these diseases are considered "black swan events". Black swan developed as a metaphor for a supposed impossibility that is contradicted with new information. Today, Black Swan Theory focuses on unexpected events of large magnitude and consequence.
与粉蠹虫和小蠹虫相关的病害构成了上个世纪树木上出现的一些最为严重的问题。它们由长喙壳目、小囊菌目和肉座菌目的真菌引起，其传播媒介为象甲科（鞘翅目）小蠹亚科（粉蠹虫和小蠹虫）及长小蠹亚科（粉蠹虫）的昆虫。其中一些问题，如荷兰榆树病，历史悠久，已得到广泛研究，人们也较为了解。相比之下，其他一些类似病害是最近才出现的，人们对其了解甚少或只是部分了解。本文将讨论这些树木病害的出现及其意外的重要性。在大多数此类相互作用中，一个潜在因素是所谓的“天真”或“新接触”寄主树与病原体和/或甲虫之间缺乏共同进化的历史。对于粉蠹虫而言，这些相互作用与对通常无害的真菌的易感性以及与健康树木的非典型关系有关（粉蠹虫更喜欢已死亡或受胁迫的树木）。有趣的是，与粉蠹虫和小蠹虫相关病害的病原体通常与昆虫存在共生关系，而这种关系并非基于植物致病性。其中一些最令人担忧和具有破坏性的病害被视为“黑天鹅事件”。“黑天鹅”最初是一个比喻，用来形容一种被认为不可能发生但却与新信息相矛盾的事情。如今，黑天鹅理论关注的是具有重大影响和后果的意外事件。
