| Title: | Rapid monoterpene induction promotes the susceptibility of a novel host pine to mountain pine beetle colonization but not to beetle-vectored fungi |
| Author(s): | Cale JA; Muskens M; Najar A; Ishangulyyeva G; Hussain A; Kanekar SS; Klutsch JG; Taft S; Erbilgin N; |
| Address: | "Department of Renewable Resources, 442 Earth Sciences Building, University of Alberta, Edmonton, AB T6G 2E3, Canada" |
| ISSN/ISBN: | 1758-4469 (Electronic) 0829-318X (Linking) |
| Abstract: | "Chemical induction can drive tree susceptibility to and host range expansions of attacking insects and fungi. Recently, mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) has expanded its host range from its historic host lodgepole pine (Pinus contorta var. latifolia Douglas ex Loudon) to jack pine (Pinus banksiana Lamb) in western Canada. Beetle success in jack pine forests likely depends upon the suitability of tree chemistry to MPB and its symbiotic phytopathogenic fungi. In particular, how rapid induced defenses of jack pine affect MPB colonization and the beetle's symbionts is unknown. In the field, we characterized and compared differences in rapid induced phloem monoterpenes between lodgepole and jack pines in response to various densities of Grosmannia clavigera (Robinson-Jeffery and Davidson)-a MPB symbiotic fungus used to simulate beetle attack-inoculations. Overall, lodgepole pine had higher limonene and myrcene, but lower alpha-pinene, concentrations than jack pine. However, myrcene concentrations in jack pine increased with inoculation density, while that in lodgepole pine did not respond to density treatments. We compared the growth and reproduction of MPB's symbiotic fungi, G. clavigera, Ophiostoma montium (Rumford) von Arx and Leptographium longiclavatum Lee, Kim and Breuil, grown on media amended with myrcene, alpha-pinene and limonene at concentrations reflecting two induction levels from each pine species. Myrcene and alpha-pinene amendments inhibited the growth but stimulated the reproduction of G. clavigera, whereas limonene stimulated its growth while inhibiting its reproduction. However, the growth and reproduction of the other fungi were generally stimulated by monoterpene amendments. Overall, our results suggest that jack pine rapid induction could promote MPB aggregation due to high levels of alpha-pinene (pheromone precursor), a positive feedback of myrcene (pheromone synergist) and low levels of limonene (resistance). Jack pine is likely as susceptible to MPB-vectored fungi as lodgepole pine, indicating that jack pine induction will likely not adversely affect symbiont activities enough to inhibit the invasion of MPB into jack pine forests" |
| Keywords: | Animals Coleoptera/*microbiology/*pathogenicity Fungi/pathogenicity Monoterpenes/*metabolism Pinus/*metabolism/microbiology/*parasitology bark beetle outbreak insect invasion jack pine lodgepole pine ophiostomatoid fungi range expansion; |
| Notes: | "MedlineCale, Jonathan A Muskens, Marlena Najar, Ahmed Ishangulyyeva, Guncha Hussain, Altaf Kanekar, Sanat S Klutsch, Jennifer G Taft, Spencer Erbilgin, Nadir eng Research Support, Non-U.S. Gov't Canada 2017/10/07 Tree Physiol. 2017 Dec 1; 37(12):1597-1610. doi: 10.1093/treephys/tpx089" |
