Next-generation alcohol biosensor for detecting the emission of stress-induced ethanol from trees

Ambrosia beetles (Coleoptera: Curculionidae) are destructive wood-boring pests of horticultural trees. Ethanol is emitted from trees in response to various physiological stressors, especially flooding and freezing. Ambrosia beetles use ethanol to locate vulnerable trees for infestation. Since trees in the early stages of physiological stress can be asymptomatic while emitting stress-induced ethanol, rapidly detecting the emission of ethanol would aid in identifying trees at risk of being infested by ambrosia beetles. The primary objective of our study was to determine whether a next-generation alcohol biosensor could detect ethanol emissions from flood-stressed trees prior to a mass attack by ambrosia beetles. The BACtrack® wearable alcohol biosensor was selected for testing. The BACtrack biosensor was positioned at the base of stems on flood-stressed trees. A gasket was used to ensure a seal between the bark surface and the biosensor. Sugar maple, Acer saccharum, trees were flood-stressed using a pot-in-pot system and held within an environmental growth chamber or deployed under field conditions. Non-flooded control trees received a standard irrigation regime. Experiments conducted in a growth chamber confirmed that the BACtrack biosensor detected ethanol emitted from flood-stressed maples, but not from non-flooded control trees. Under field conditions, the BACtrack biosensor was able to detect ethanol emissions from flood-stressed maples before mass attacks by invasive ambrosia beetles. These studies will aid in efforts to develop an ethanol biosensor that alerts arborists and pest management specialists to trees at risk of infestation by invasive ambrosia beetles.