Interaction of insecticide and media moisture on ambrosia beetle (Coleoptera: Curculionidae) attacks on ornamental trees

Authors: ANDERSON, AMANDA - North Carolina State University; Ranger, Christopher; FRANK, STEVE - North Carolina State University

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2017
Publication Date: 10/23/2017
Publication URL: http://handle.nal.usda.gov/10113/6472480
Citation: Anderson, A., Ranger, C.M., Frank, S. 2017. Interaction of insecticide and media moisture on ambrosia beetle (Coleoptera: Curculionidae) attacks on ornamental trees. Environmental Entomology. 46:1390-1396.

Interpretive Summary: Exotic ambrosia beetles are among the most economically damaging pests of ornamental trees in nurseries. Growers have had few tactics besides insecticide applications to reduce ambrosia beetle attacks but recent research shows that reducing flood stress by maintaining media moisture below a 50% threshold could help. We compared the efficacy of managing media moisture and insecticide applications for reducing ambrosia beetle attacks on three tree species commonly grown in nurseries. Flooded dogwoods were heavily attacked even when sprayed preventively with permethrin. No non-flooded dogwoods were attacked, thereby demonstrating the greater value of media moisture thresholds than insecticides for these species. In contrast, flooded and non-flooded Japanese snowbell trees were heavily attacked even when sprayed with permethrin. Overall, our results support water management below the 50% threshold as the first line of defense against ambrosia beetle attacks and for some trees like dogwood may be the only necessary defense.

Technical Abstract: Exotic ambrosia beetles, particularly Xylosandrus crassiusculus (Motschulsky) and Xylosandrus germanus (Blandford), are among the most economically damaging pests of ornamental trees in nurseries. Growers have had few tactics besides insecticide applications to reduce ambrosia beetle attacks but recent research shows that reducing flood stress by maintaining media moisture below a 50% threshold could help. We compared the efficacy of managing media moisture and insecticide applications for reducing ambrosia beetle attacks on three tree species commonly grown in nurseries. Flooded Cornus kousa and C. florida were heavily attacked even when sprayed preventively with permethrin. No non-flooded C. kousa or C. florida were attacked demonstrating the greater value of media moisture thresholds than insecticides for these species. In contrast, flooded and non-flooded Styrax japonicus were heavily attacked even when sprayed with permethrin. This differs from a previous study in Ohio in which non-flooded S. japonicus were not attacked and suggests potential differences in susceptibility due to climate or composition of the beetle community which in North Carolina is dominated by X. crassiusculus rather than X. germanus. Interestingly, although X. germanus was only 10% of beetles captured in traps it comprised half the beetles reared from experimental trees. In addition, X. germanus was reared from S. japonicus in greater frequency than C. florida suggesting a preference for this species. Overall, our results support water management below the 50% threshold as the first line of defense against ambrosia beetle attacks and for some trees like Cornus species may be the only necessary defense.