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Ambrosia Beetle (Coleoptera: Curculionidae) Responses to Volatile Emissions Associated With Ethanol-Injected Magnolia virginiana

Ranger, Christopher M., Reding, Michael E., Schultz, Peter B., Oliver, Jason B.
Environmental entomology 2012 v.41 no.3 pp. 636
Curculionidae, Magnolia virginiana, Xylosandrus, ambrosia beetles, bait traps, bark, bolts, dose response, emissions, ethanol, gas chromatography, insect attractants, insect control, insect pests, mass spectrometry, microextraction, monoterpenoids, nursery stock, ornamental trees, plant pests, stems, volatile compounds
Xylosandrus germanus (Blandford) and other species of ambrosia beetles are key pests of ornamental nursery trees. A variety of laboratory- and field-based experiments were conducted in pursuit of improved monitoring strategies and to develop a trap tree strategy for ambrosia beetles. Traps baited with bolts prepared from Magnolia virginiana L. injected with ethanol caught five times more X. germanus than ethanol-baited traps. Basal stem injections of ethanol into M. virginiana induced more ambrosia beetle attacks than irrigating or baiting with ethanol, and no attacks occurred on water-injected trees. A positive correlation was also detected between concentration of injected ethanol and cumulative attacks. Solid phase microextraction-gas chromatography-mass spectrometry characterized bark emissions from ethanol- and water-injected M. virginiana at 1, 2, 10, and 16 d after treatment. Ethanol emission from injected trees steadily declined from 1 to 16 d after treatment, but was not emitted from water-injected trees. A variety of monoterpenes were also emitted in trace amounts from the ethanol- and water-injected trees. Antennal responses of X. germanus via gas chromatography-electroantennographic detection to volatiles from ethanol-injected M. virginiana occurred for ethanol, but not the various monoterpenes. X. germanus and other ambrosia beetles were also equally attracted to traps baited with ethanol alone compared with a synthetic mixture of ethanol plus various monoterpenes formulated to mimic ethanol-injected M. virginiana. Injecting concentrated solutions of ethanol into trees may be useful for establishing odor-based trap trees, which could aid with monitoring programs and/or potentially deflect ambrosia beetles away from valuable nursery stock.