Interception strategies for managing exotic ambrosia beetles (Coleoptera: Curculionidae) in nurseries

Authors: Reding, Michael - Mike; Ranger, Christopher; ADDESSO, KARLA - Tennessee State University; Werle, Christopher; OLIVER, JASON - Tennessee State University

Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2021
Publication Date: 7/5/2022
Citation: Reding, M.E., Ranger, C.M., Addesso, K., Werle, C.T., Oliver, J. 2022. Interception strategies for managing exotic ambrosia beetles (Coleoptera: Curculionidae) in nurseries. Journal of Entomological Science. 57(3):436-442. https://doi.org/10.18474/JES21-60.
DOI: https://doi.org/10.18474/JES21-60

Interpretive Summary: Invasive ambrosia beetles a serious pests in ornamental tree nurseries, apple orchards and other tree crops in North America. They move into tree crops from nearby woodlands each year. Growers control ambrosia beetles primarily by spraying trees with conventional insecticides. However, efficacy of insecticides has been inconsistent. The most damaging species of ambrosia beetles are easily captured in ethanol-baited traps. Ethanol-baited traps may be useful for intercepting beetles as they move into tree crops from nearby woodlands and reduce damage or at least make insecticides more effective. Ethanol-baited intercept traps were tested in commercial tree nurseries to determine whether ambrosia beetle activity would be reduced. Even though thousands of ambrosia beetles were captured by intercept traps, captures of beetle in sentinel traps within nurseries were not reduced. In this research ethanol-baited traps were not effective for reducing beetle activity in nurseries. Additional research is needed to test stronger ethanol baits and additional materials as baits.

Technical Abstract: Exotic ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are damaging pests of ornamental tree nurseries and other tree crops in North America. Management is based on keeping trees healthy and trunk sprays of insecticides to prevent colonization attempts. The current research tested ethanol-baited traps as a tactic for intercepting ambrosia beetles emigrating into ornamental tree nurseries from overwintering sites in woodlands. Sentinel traps were positioned within nurseries at various distances (13m, 25m, 50m and 100m) from ambrosia beetle overwintering sites in adjacent woodlands, and intercept traps were placed at the woodland/nursery interface. Intercept traps were tested at two densities, 5 (25m spacing) or 11 (10m spacing) traps guarding plots (100m width) in 2015 and 2016, respectively. Intercept traps captured thousands of ambrosia beetles but did not reduce captures in sentinel traps compared to unguarded plots regardless of proximity to the intercept traps. Additionally, ethanol-injected trap trees were used to attract ambrosia beetles away from insecticide treated trees to determine whether colonization attempts on treated trees could be reduced and efficacy of insecticide treatments improved. Insecticide treated trees were injected with 5% ethanol and paired with high attraction trap-trees injected with 50% ethanol or equivalent attraction trees injected with 5% ethanol. The presence of trap-trees did not prevent colonization attempts on insecticide treated trees, and there were no differences in numbers of attempts on trees paired with high or equivalent attraction trap-trees. Interception tactics were not effective for reducing ambrosia beetle activity in nurseries or colonization attempts on ornamental trees.