Journal of Chemical Ecology

, Volume 41, Issue 9, pp 848–852

Fungal Symbionts of the Spruce Bark Beetle Synthesize the Beetle Aggregation Pheromone 2-Methyl-3-buten-2-ol

  • Tao Zhao
  • Karolin Axelsson
  • Paal Krokene
  • Anna-Karin Borg-Karlson
Rapid Communication

DOI: 10.1007/s10886-015-0617-3

Cite this article as:
Zhao, T., Axelsson, K., Krokene, P. et al. J Chem Ecol (2015) 41: 848. doi:10.1007/s10886-015-0617-3

Abstract

Tree-killing bark beetles depend on aggregation pheromones to mass-attack their host trees and overwhelm their resistance. The beetles are always associated with phytopathogenic ophiostomatoid fungi that probably assist in breaking down tree resistance, but little is known about if or how much these fungal symbionts contribute to the beetles’ aggregation behavior. In this study, we determined the ability of four major fungal symbionts of the spruce bark beetle Ips typographus to produce beetle aggregation pheromones. The fungi were incubated on Norway spruce Picea abies bark, malt agar, or malt agar amended with 0.5 % 13C glucose. Volatiles present in the headspace of each fungus were analyzed for 7 days after incubation using a SPME autosampler coupled to a GC/MS. Two Grosmannia species (G. penicillata and G. europhioides) produced large amounts of 2-methyl-3-buten-2-ol (MB), the major component in the beetles’ aggregation pheromone blend, when growing on spruce bark or malt agar. Grosmannia europhioides also incorporated 13C glucose into MB, demonstrating that the fungi can synthesize MB de novo using glucose as a carbon source. This is the first clear evidence that fungal symbionts of bark beetles can produce components in the aggregation pheromone blend of their beetle vectors. This provides new insight into the possible ecological roles of fungal symbionts in bark beetle systems and may deepen our understanding of species interactions and coevolution in these important biological systems.

Keywords

Scolytinae Bluestain fungi Plant-insect-microbe interactions 

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Tao Zhao
    • 1
  • Karolin Axelsson
    • 1
  • Paal Krokene
    • 2
  • Anna-Karin Borg-Karlson
    • 1
  1. 1.Department of ChemistryRoyal Institute of TechnologyStockholmSweden
  2. 2.Norwegian Institute of Bioeconomy ResearchÅsNorway

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