Comparing verbenone‐based repellents for ambrosia beetle management in eastern apple orchards

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are damaging pests of apple orchards in the eastern United States, where attacks on stressed trees can lead to tree decline and economic loss. Semiochemical‐based repellents, such as verbenone, offer a potential complement to insecticide‐based management, but their performance across regions, pest species and formulations is not well characterized. We evaluated three verbenone‐based repellents, two trunk‐applied SPLAT® VERB formulations and a commercially available verbenone sachet in commercial apple orchards in Ohio, New York and Pennsylvania over a 12‐week period. Beetle activity was monitored within plots using low‐dose ethanol‐baited traps. Ambrosia beetle assemblages were regionally similar but differed in species dominance. Xylosandrus germanus was the most abundant species in Ohio, Anisandrus maiche dominated in New York and Xylosandrus crassiusculus in Pennsylvania. Across all states, repellent treatments significantly reduced captures of dominant ambrosia beetle species relative to untreated controls. In Ohio and New York, all formulations similarly suppressed X. germanus and A. maiche . In Pennsylvania, verbenone sachets were more effective than the commercial SPLAT® VERB for all species. Visible phytotoxicity was observed on apple foliage and fruit following an independent phytotoxicity assessment of both SPLAT® formulations. Verbenone‐based repellents effectively reduced ambrosia beetle trap capture across multiple regions and species; however, formulation‐specific efficacy and phytotoxicity limit their utility, suggesting that further refinement of repellent delivery systems is needed to support broader adoption in apple production systems.