Department of Forestry and Environmental Conservation, Clemson University, Clemson, SC, 29634, USA.
Environ Entomol. 2022 Feb 16;51(1):216-221. doi: 10.1093/ee/nvab136.
Wild Callery pear (Pyrus calleryana Decne.) results from a cross between various cultivars of P. calleryana and any other Pyrus individual. While many cultivars of this species are still commercially produced and sold for horticultural purposes in the United States, Callery pear is a detrimental invasive species that encroaches on many managed and natural areas, damages equipment and injures people, pets, and livestock with its thorny branches, and likely causes detrimental ecological impacts. Despite its importance as an invasive species, the mechanisms behind Callery pear's invasion and spread are unclear. To identify potential drivers of invasion, we quantified feeding of generalist and specialist herbivores on Callery pear and four native tree species, based on insect host ranges, with choice and no-choice experiments followed by field surveys of herbivory on these same tree species. Feeding by all herbivores was lower on Callery pear than on native tree species in no-choice assays. Specifically, feeding on Callery pear was moderate by generalists and very low by specialists. Specialist feeding on Callery pear was comparable to native species in choice assays but was significantly reduced in no-choice assays. Reduced specialist feeding along with moderate generalist feeding on Callery pear in the field provides evidence for the Enemy Release Hypothesis as a potential driving mechanism behind its invasion success.
野生西洋梨（Pyrus calleryana Decne.）是由西洋梨的不同品种与其他任何梨属个体杂交产生的。虽然该物种的许多品种仍在美国被商业化生产和销售用于园艺目的，但西洋梨是一种有害的入侵物种，它侵占了许多管理和自然区域，其多刺的树枝会损坏设备并伤害人和宠物以及牲畜，可能会对生态造成有害影响。尽管它作为入侵物种的重要性，但西洋梨入侵和传播的机制尚不清楚。为了确定入侵的潜在驱动因素，我们根据昆虫的寄主范围，在选择和非选择实验的基础上，量化了一般和专门的食草动物对西洋梨和四种本地树种的取食情况，并对这些相同的树种进行了野外食草调查。在非选择试验中，所有食草动物对西洋梨的取食均低于本地树种。具体来说，一般食草动物对西洋梨的取食适中，而专门食草动物的取食非常低。在选择试验中，专门食草动物对西洋梨的取食与本地物种相当，但在非选择试验中显著减少。野外调查中，专门食草动物的取食量减少，而一般食草动物对西洋梨的取食量适中，这为“天敌释放假说”提供了证据，表明这是其成功入侵的潜在驱动机制之一。
