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Influence of flood-stress on ambrosia beetle host-selection and implications for their management in a changing climate

Ranger, Christopher M., Reding, Michael E., Schultz, Peter B., Oliver, Jason B.
Agricultural and forest entomology 2013 v.15 no.1 pp. 56
Cornus florida, Xylosandrus, acetaldehyde, acetic acid, ambrosia beetles, bark, climate change, core samplers, ethanol, flooded conditions, host plants, host preferences, host seeking, insect attractants, insect behavior, insect control, insect pests, nursery crops, ornamental trees, plant pests, plant stress, plant-insect relations, semiochemicals, spectroscopy, volatile compounds, water stress
Xylosandrus germanus (Blandford) is a key pest of ornamental nursery trees. Ethanol is the most attractive semiochemical known for X. germanus and other ambrosia beetles, and its emission from trees represents an important host-selection cue. The production and emission of ethanol can be induced by a variety of abiotic and biotic stressors, which could thereby predispose trees to attack by ethanol-responsive ambrosia beetles. To better understand ambrosia beetle host-selection behavior within ornamental nurseries, a series of experiments were conducted to examine the influence of flood-stress on the attractiveness and susceptibility of flowering dogwood, Cornus florida L. Under field conditions, more X. germanus were attracted to and landed on experimentally flood-stressed dogwoods than neighboring nonflooded controls in 2009, 2010, and 2011. Flood-stressed dogwoods were also preferentially attacked in 2009-2011, but no attacks occurred on any of the neighboring nonflooded trees. Solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) detected ethanol in tissue core samples from trunks of flooded dogwoods, but not nonflooded trees. Acetaldehyde, acetic acid, and ethanol were also detected by SPME-GC-MS in bark emissions from flooded dogwoods, but not nonflooded trees. These results demonstrate X. germanus preferentially lands on and attacks physiologically-stressed hosts over neighboring healthy trees, and further supports the role of ethanol and potentially other stress-related volatiles in mediating this interaction. Minimizing stressors known to induce the production of ethanol and other stress-related volatiles should be the primary foundation of a management plan for X. germanus and other ethanol-responsive ambrosia beetles.