Single-generation effects on terpenoid defenses in lodgepole pine populations following mountain pine beetle infestation.

Sharleen L Balogh,Dezene P W Huber,B Staffan Lindgren,Leandro Peña

doi:10.1371/journal.pone.0196063

Sharleen L Balogh, Dezene P W Huber + Show 2 more

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https://doi.org/10.1371/journal.pone.0196063

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Journal: PloS one	Publication Date: May 14, 2018
Citations: 5	License type: CC BY 4.0

Affiliation: University of Northern British Columbia

Abstract

The recent mountain pine beetle outbreak in western Canada provides an opportunity to study the selection and heritability of tree defenses. We examined terpenoid-based defenses of seedling lodgepole pines which were offspring of mature trees subjected to high levels of mountain pine beetle selective pressure. Seedlings were grown from one of three types of cones: old cones on live trees; young cones on live trees; and cones on trees killed by beetles. Offspring thus represented crosses of non-surviving (NS) x surviving (S), S x S, and NS x NS parents, respectively. Methyl jasmonate was used to induce a defensive reaction in the seedlings. Seed source had a significant effect on levels of ten different terpenes, but not on total terpene concentrations. When the seedlings were grouped by location and treatment type, the seedlings of different cone types could be almost entirely distinguished by terpene profiles.

Highlights

The mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), is the most destructive insect pest of lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm. (Pinaceae), in western Canada, and has recently undergone the largest bark beetle outbreak in recorded history [1]
Seedlings grown from parental seed sources that had survived the MPB attack by varying amounts showed differential production of terpenes, as well as a differential production of a number of individual terpenes
In all cases, where there were differential concentrations of individual terpenes between seedlings grown from different cone types, the seedlings grown from the cones from live trees produced higher terpene concentrations than those grown from the cones of dead trees

Summary

Introduction

The mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), is the most destructive insect pest of lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm. (Pinaceae), in western Canada, and has recently undergone the largest bark beetle outbreak in recorded history [1]. (Pinaceae), in western Canada, and has recently undergone the largest bark beetle outbreak in recorded history [1] This outbreak has created substantial selective pressure on the lodgepole pine trees of the region. In spite of extremely high rates of mortality, including of immature trees [2], some mature trees survived the outbreak This has created an ideal opportunity to study potential differences in defensive capabilities between those trees that survived the outbreak and those that did not, and whether these differences are heritable. After a pioneer female beetle enters the bark of a potential host tree, a signaling cascade is initiated to attract male and further female beetles.

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