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. 2022 Feb 16;51(1):216-221.
doi: 10.1093/ee/nvab136.

Into the Wild: Evidence for the Enemy Release Hypothesis in the Invasive Callery Pear (Pyrus calleryana) (Rosales: Rosaceae)

Jessica A Hartshorn  1 , J Forest Palmer  1 , David R Coyle  1
Affiliations

Into the Wild: Evidence for the Enemy Release Hypothesis in the Invasive Callery Pear (Pyrus calleryana) (Rosales: Rosaceae)

Jessica A Hartshorn et al. Environ Entomol. .

Abstract

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.

Keywords: Hyphantria cunea; Malacasoma americanum; enemy release hypothesis; herbivore; invasive species.

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Figures

Fig. 1.
Fig. 1.
Experimental design of choice (right) and no-choice (left) assays. Leaf discs were randomly placed in cages.
Fig. 2.
Fig. 2.
Mean percent of each leaf eaten (± SE) during field surveys in the Clemson Experimental Forest on red maple, mockernut hickory, black cherry, and Callery pear.
See this image and copyright information in PMC

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