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Three-way interactions among ectomycorrhizal mutualists, scale insects, and resistant and susceptible pinyon pines

Gehring, Catherine A. and Cobb, Neil S. and Whitham, Thomas G. (1997) Three-way interactions among ectomycorrhizal mutualists, scale insects, and resistant and susceptible pinyon pines. American Naturalist, 149 (5). pp. 824-841. ISSN 1537-5323


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Publisher’s or external URL: http://dx.doi.org/10.1086/286026


How the pinyon needle scale Matsucoccus acalyptus, affects and is affected by the ectomycorrhizal mutualists found on the roots of scale-resistant and -susceptible Pinus edulis was examined in a 9 year experiment conducted in Arizona, USA. Three major results emerged. First, removal experiments demonstrated that scales negatively affected ectomycorrhiza. Second, although ectomycorrhiza could either positively or negatively influence scale performance by improving plant vigour or increasing plant investment in antiherbivore defences, no ectomycorrhizal effect on scale mortality was found when levels of ectomycorrhiza were experimentally enhanced. This represented the first test of whether ectomycorrhiza promote plant resistance and contrasted with studies showing that arbuscular mycorrhiza negatively affected herbivores. Third, pinyon resistance to scales mediated the asymmetrical interaction between fungal mutualists and scale herbivores. High scale densities suppressed ectomycorrhizal colonization, but only on trees susceptible to scales. Similarities between mycorrhiza-herbivore interactions and competitive interactions among herbivores suggested broader generalities in the way above-ground herbivores interact with below ground plant associates. However, because mycorrhiza are mutualists, mycorrhiza-herbivore interactions do not fit within traditional competition paradigms. The widespread occurrence and importance of both herbivores and mycorrhizae argue for incorporating their interactions into ecological theory.

Item Type: Article
Publisher’s Statement: © 1997 by The University of Chicago Press. All rights reserved.
ID number or DOI: 10.1086/286026
Keywords: Plant Pathology: Insects; Mycorrhizae; agricultural entomology; Animal Ecology; arbuscular mycorrhizal infection; Arizona; arthropods; Biology; ciliata ssp ambigua; Coccoidea; Communities; Competition; Developed Countries; Ecology; ectomycorrhizas; environmental-stress; eukaryotes; forest trees; Fungi; growth; gymnosperms; Hemiptera; herbivory; Hexapoda; Homoptera; host-plant; insect pests; Insects; Interactions; Invertebrates; Margarodidae; Matsucoccus; Matsucoccus acalyptus; Mycorhizal fungi; Mycorhizas; Mycorrhizas and Fungi of Economic Importance; natural conditions; North America; OECD Countries; pest insects; phytopathogens; phytopathology; Pinaceae; Pinopsida; Pinus; Pinus edulis; plant pathogens; Plant Pathology; Plants; Spermatophyta; Sternorrhyncha; trees; Woody plants
Subjects: Q Science > QL Zoology
S Agriculture > SD Forestry
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Biological Sciences
Date Deposited: 13 Oct 2015 17:29
URI: http://openknowledge.nau.edu/id/eprint/1391

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