Location: Application Technology Research
Project Number: 5082-22000-014-000-D
Project Type: In-House Appropriated
Start Date: Dec 28, 2015
End Date: Jul 5, 2018
Objective 1. Develop improved techniques for monitoring invasive ambrosia beetles in nurseries based on new knowledge of behavior, movement, and flight activity across different habitats. Sub-Objective 1a: Assess the seasonal activity of attacks using flood-stressed trees, ethanol-baited trees, and ethanol-baited traps. Sub-Objective 1b: Characterize abundance, diversity, distribution, and seasonal movement of Xylosandrus species within nurseries and surrounding habitats; determine the primary sources of ambrosia beetles invading nurseries with emphasis on Xylosandrus species. Objective 2. Characterize the role of tree health on the host-selection and host-preference behavior of ambrosia beetles in ornamental nurseries. Sub-Objective 2a: Compare the capacity of drought-stress and flood-stress to predispose trees to attack. Sub-Objective 2b: Assess the impact of frost injury on predisposing trees to attack. Sub-Objective 2c: Compare the colonization success of ambrosia beetles on stressed vs. healthy hosts. Sub-Objective 2d: Determine the susceptibility and tolerance of trees to colonization by ambrosia beetles during spring and summer; determine colonization behavior and activity of summer generations of X. germanus. Sub-Objective 2e: Characterize and identify time-course volatile emissions from living, but weakened trees used by ambrosia beetles during host-selection. Objective 3. Develop improved technology for applying or improving the efficacy of chemicals to effectively manage ambrosia beetles and evaluate alternatives to conventional insecticides for managing ambrosia beetles in nurseries. Sub-objective 3a: Assess the ability of insecticides to reduce attacks and disrupt colonization of stressed trees by ambrosia beetles. Sub-Objective 3b: Test efficacy of a variable rate, sensor-guided spray system for applying ambrosia beetle controls to nursery trees. Sub-Objective 3c: Evaluate capacity of ethanol-injected trees to reduce attack pressure on vulnerable trees and improve efficacy of insecticide treatments. Sub-Objective 3d: Optimize an ethanol-based interception tactic for invasive ambrosia beetles. Sub-Objective 3e: Integrate repellents and attractants for deflecting beetles away from vulnerable trees and intercepting them with trapping tactics as part of a push-pull management strategy.
Objective 1a: The seasonal activity of ambrosia beetle attacks needs to be characterized to develop non-chemical interception strategies against ambrosia beetles. Seasonal activity of attacks will be characterized on flood-stressed trap trees and ethanol-baited trees, and compared against ethanol-baited traps. Objective 1b: The local sources of ambrosia beetles colonizing nursery trees are uncertain. Resident populations within nurseries are unlikely because growers apply insecticides to prevent colonization, and remove infested trees when colonization is detected. Habitats, especially wooded areas, surrounding nurseries are potential sources of beetles infesting nurseries. Objective 2a: The capacity of drought stress to predispose trees to attack will initially be assessed using species with varying degrees of drought intolerance. Objective 2b: Preliminary studies indicated that low temperature stress predisposes trees to attack by ambrosia beetles. Experiments under controlled conditions will be used to characterize the capacity of frost injury to predispose trees to attack, which will help growers identify vulnerable species and make more informed management decisions. Objective 2c: The ability of X. germanus to colonize stressed vs. healthy hosts will be compared. Flooding, which predisposes trees to attack by X. germanus, will be used as the stress factor. Objective 2d: Seasonal vulnerability of trees to attacks by ambrosia beetles will be examined. Trees in early stages of post-dormancy development and summer trees (full canopies) will be compared. Objective 2e: Ethanol is currently the most important compound known for ambrosia beetle host location, but other compounds emitted from physiologically-stressed trees may also play a role in signaling host vulnerability and suitability. Flooding will be used to stress trees and make them attractive to ambrosia beetles. The time-course emission of volatiles will be collected from flood-stressed and healthy trees to identify compounds attractive to ambrosia beetles. Objective 3a: Trunk applications of conventional and botanical insecticides will on trees stressed by flooding. In addition, trees will be injected with different concentrations of ethanol to determine whether the stress level influences efficacy of insecticides protecting trees from attacks by ambrosia beetles. Objective 3b: A prototype variable sensor guided sprayer will be tested as a delivery system for trunk applied insecticides to protect trees from ambrosia beetle attacks. Objective 3c: Ethanol-injected trees will be tested as trap trees to reduce attack pressure on nursery trees and enhance efficacy of protective trunk sprays. Objective 3d: Ethanol-baited traps and ethanol-injected trees will be tested as interception devices to reduce colonization of nursery trees by ambrosia beetles. Objective 3e: A push-pull management strategy will be pursued by combining the use of repellents with the strategic placement of highly attractive traps or trap trees in between nurseries and neighboring woodlots.