Ecology and Integrated Management of Ambrosia Beetles in Ornamental Nursery Trees

Ambrosia beetles (Coleoptera: Scolytidae) (AB) are small fungus-farming beetles that damage stressed nurseries trees. Under anaerobic stress, trees emit ethanol which is the primary cue for AB to locate suitable hosts. This study conducted experiments to help develop a push-pull management strategy and assess tree stress levels. First, two commercial wood dowel types – balsa wood (Ochroma pyramidale [Cav. ex Lam.]) and tulip poplar (Liriodendron tulipifera L.) – were evaluated as monitoring tools with ethanol. Second, repellent treatments were tested to determine efficacy against AB: cedarwood oil (CO2-derived), 2-butoxyethanol, 2-ethyl-1-hexanol, Beetle Guard (BG), and untreated control. Following this, ethanol-soaked flowering dogwood (Cornus florida L.) bolts were used to determine BG’s repellency against AB at increasing rates of ethanol emission and at an increasing distance from the repellent source. The BG product was effective in repellent experiments at increasing rates of ethanol at up to 2 m from the source. Third, two low-cost ethanol detectors (Alcohol Strip and Draeger PAC 8000) were used to quantify ethanol emissions from stressed trees root, bark, and twig tissue. Ethanol emission was verified using solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). Ambrosia beetle attacks were assessed throughout the experiment. The overall thesis shows 1) balsa wooden dowel traps were promising for standardizing AB monitoring, (2) Beetle Guard may be useful in reducing AB attacks, and (3) low-cost field detectors can be used to assess ethanol emission from stressed trees. These results offer promising AB management strategies in ornamental nurseries that are more efficient and cost-efficient than current practices