D3426: Improving the management of ambrosia beetles as pests of ornamental trees

Ambrosia beetles (Coleoptera: Scolytinae) are one of the key pests for ornamental growers in Virginia. Currently, ethanol baited traps are used to document the first appearance of these beetles in affected systems. Once beetles are flying, growers opt to spray pyrethroids to protect trunks and branches of susceptible trees in their commercial blocks. Several trials have been run to collect data on how to improve the trapping efforts of adults, as well as proposing alternative chemical tactics to pyrethroids. Changing the killing agent in our traps, from soapy water to a marine antifreeze significantly increased adult captures per plastic bottle trap. One-foot wood bolt, filled with ethanol, continued to provide the most reliable data on attracting adults resulting in higher attacks when compared to the rest of bolt treatments. Our historical trapping data indicates that the granulate ambrosia beetle (Xylosandrus crassiusculus) is expected to peak between early April and late May; however, these peaks could vary depending on the geographical region. Wood bolts coated with permethrin had the lowest number of attacks when compared to untreated bolts, followed by the ones treated with indoxacarb and the combo of spinetoram + sulfoxaflor, respectively. Adult trapping efforts let growers fine-tune the window for the timing of insecticide treatments, avoiding sprays applied after the peak of activity of adults. Ongoing efforts will continue to look for alternatives to pyrethroid treatments, where we will be testing the efficacy of additional active ingredients with a fit into the ornamental tree production.