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Title: AVOIDANCE OF NONHOST PLANTS BY A BARK BEETLE, PITYOGENES BIDENTATUS, IN A FOREST OF ODORS

Author
item Byers, John
item ZHANG, QING-HE - SWEDISH UNIV ALNARP
item BIRGERSSON, GORAN - GOTEBORG UNIV SWEDEN

Submitted to: Naturwissenschaften
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2004
Publication Date: 4/8/2004
Citation: Byers, J.A., Zhang, Q., Birgersson, G. 2004. Avoidance of nonhost plants by a bark beetle, pityogenes bidentatus, in a forest of odors. Naturwissenschaften 91:215-219.

Interpretive Summary: The bark beetle, Pityogenes bidentatus (Coleoptera: Scolytidae), occurs in mixed conifer and deciduous forests of northern Europe, feeding on limbs of Scotch pine, Pinus sylvestris. Volatiles from leaves or bark of several common nonhost trees in the habitat (e.g., mountain ash, Sorbus aucuparia; oak, Quercus robur; and alder buckthorn, Frangula alnus) dramatically reduced the attraction of the bark beetles to their aggregation pheromone components, cis-verbenol and grandisol, in the field. Furthermore, odors from nonhost blueberry (Vaccinium myrtillus), raspberry (Rubus idaeus), and grass (Deschampsia flexuosa) similarly reduced attraction. Collections of volatile odors from field-tested plant tissues were analyzed by GC/MS and shown to contain monoterpenes, sesquiterpenes, and 'green-leaf' alcohols, several of which reduced attraction to pheromone traps in the field (e.g. 1-octene-3-ol and B-caryophyllene). Some of the identified chemicals, along with the pheromone components, elicited electrical responses in the antennae of the beetles (electroantennographic responses). These findings indicate that the bark beetle, while in flight, avoids odors from nonhosts as part of the host-finding process, which is more complex than envisioned previously.

Technical Abstract: The bark beetle, Pityogenes bidentatus (Coleoptera:Scolytidae), searches in mixed conifer and deciduous forests of northern Europe for suitable branches of its host, Scots pine (Pinus sylvestris).We tested whether odors from several diverse nonhost trees and plants common in the habitat (e.g., mountain ash, Sorbus aucuparia; oak, Quercus robur; alder buckthorn, Frangula alnus; blueberry, Vaccinium myrtillus; raspberry, Rubus idaeus; and grass, Deschampsia flexuosa) would reduce the attraction of the bark beetle to traps releasing its aggregation pheromone components in the field. Volatiles from the leaves or bark of each of these plants significantly reduced the attraction of the beetles to their pheromone. Odors collected from these nonhosts and analyzed by GC/MS contained monoterpenes, sesquiterpenes, and "green-leaf "alcohols, several of which (e.g.,1-octene-3-ol and B-caryophyllene) reduced the attraction to pheromone in the field and elicited electroantennographic responses. In the laboratory, reproduction by the beetle was marginal in nonhost Norway spruce, Picea abies, and was absent in the other nonhost trees. Olfactory avoidance of unsuitable nonhosts may have evolved due to advantages in avoiding mistakes during host selection.