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Title: Conophthorin enhances the electroantennogram and field behavioral response of Xylosandrus germanus (Coleoptera: Curculionidae) to ethanol

Author
item Ranger, Christopher
item GORZLANCYK, AUSTIN - Auburn University
item ADDESSO, KARLA - Tennessee State University
item OLIVER, JASON - Tennessee State University
item Reding, Michael - Mike
item SCHULTZ, PETER - Virginia Polytechnic Institution & State University
item HELD, DAVID - Auburn University

Submitted to: Agricultural and Forest Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2014
Publication Date: 4/11/2014
Publication URL: http://handle.nal.usda.gov/10113/59726
Citation: Ranger, C.M., Gorzlancyk, A.M., Addesso, K., Oliver, J.B., Reding, M.E., Schultz, P.B., Held, D.W. 2014. Conophthorin enhances the electroantennogram and field behavioral response of Xylosandrus germanus (Coleoptera: Curculionidae) to ethanol. Agricultural and Forest Entomology. DOI 10.1111/afe 12062.

Interpretive Summary: Ethanol acts as an attractant that ambrosia beetles use to locate living, but weakened trees. Conophthorin is a compound associated with the bark of a variety of trees and enhances ambrosia beetle attraction to vulnerable trees. Electroantennogram (EAG) and field trapping experiments were conducted with conophthorin and other selected compounds to assess their influence on the response of ambrosia beetles to ethanol. Compounds were chosen based on their likelihood of enhancing (i.e. conophthorin), reducing (i.e. verbenone), or having a negligible effect (i.e. lineatin, retusol, sulcatol, and terpinolene). Ethanol plus conophthorin elicited a larger EAG response by the ambrosia beetle Xylosandrus germanus than ethanol plus any of the remaining compounds at 0.2, 2, and 200 µg. EAG responses to ethanol plus the remaining compounds were indistinguishable. Ethanol plus conophthorin also attracted more X. germanus and other ambrosia beetles than traps baited with ethanol alone. In contrast, retusol, sulcatol, terpinolene, and verbenone reduced the attractiveness of ethanol to X. germanus and other ambrosia beetles. These results indicate that compounds can enhance (i.e. conophthorin) or reduce (i.e. retusol, terpinolene, and verbenone) ambrosia beetle responses to ethanol. Thus, conophthorin may be useful for improving trap attraction to ambrosia beetles, while retusol, terpinolene, and verbenone may be useful for repelling beetles.

Technical Abstract: Ethanol acts as a long range cue that aids Xylosandrus germanus (Blandford) in locating living, but weakened trees. Conophthorin is associated with a variety of deciduous trees and enhances X. germanus’ attraction to vulnerable trees. Electroantennogram (EAG) and field trapping experiments were conducted with conophthorin and other selected semiochemicals to assess their influence on X. germanus’ response to ethanol and determine if EAG responses provided an indication of field behavioral activity. Semiochemicals were chosen based on their likelihood of enhancing (i.e. conophthorin), reducing (i.e. verbenone), or having a negligible effect (i.e. lineatin, retusol, sulcatol, and terpinolene). Ethanol plus conophthorin elicited a larger EAG response amplitude than ethanol plus any of the remaining semiochemicals at stimulus concentrations of 0.2, 2, and 200 µg. EAG responses to ethanol plus the remaining semiochemicals were indistinguishable. Ethanol plus conophthorin attracted more X. germanus, Euwallacea validus (Eichhoff), and Xyleborus pelliculosus Eichhoff than traps baited with ethanol alone, and a synergistic effect was detected for X. germanus and E. validus. In contrast, retusol, sulcatol, terpinolene, and verbenone reduced the attractiveness of ethanol to X. germanus, E. validus, Monarthrum fasciatum (Say), Xyleborinus saxesenii (Ratzeburg), Xylosandrus crassiusculus (Motschulsky), X. pelliculosus, and/or Anisandrus sayi Hopkins. While ethanol acts as an important olfactory cue for X. germanus, other volatiles can enhance (i.e. conophthorin) or reduce (i.e. retusol, terpinolene, and verbenone) orientation to ethanol. The larger EAG response generally elicited by conophthorin, and corresponding enhanced field activity, also suggests EAG analyses may be useful for identifying potential attractants.