Attraction of invasive ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) to ethanol-treated tree bolts.
Ethanol-treated bolts (tree stem sections) have potential as monitoring and pesticide screening tools for ambrosia beetles (Coleoptera: Curculionidae: Scolytinae). Bolts were infused with ethanol by immersing them for at least 24 h. Attacks on ethanol-treated bolts by Xylosandrus species were compared with captures in ethanol-baited traps. Bolts infused in ethanol were usually as attractive or more attractive to Xylosandrus germanus (Blandford) than ethanol-baited bottle traps. Xylosandrus crassiusculus (Motschulsky) were more attracted to bolts than trap in some experiments, but numbers were low and differences were usually not significant. Two techniques for treating bolts with ethanol were compared. Attraction of ambrosia beetles to ethanol-infused bolts were compared with bolts with a drilled cavity filled with ethanol. Drilled bolts filled with ethanol were attractive to X. germanus and were reliably attacked, but numbers of beetles were often lower than in traps and infused bolts. Aged and fresh ethanol-infused bolts were compared with evaluate residual attractiveness. Bolts aged 7 d usually had fewer X. germanus than fresh bolts and traps, and bolts aged 14 d had no beetles. Ethanol-infused bolts from different species of trees were compared. Xylosandrus germanus attacked all species tested with more attacks usually in red maple (Acer rubrum L.). Anisandrus maiche Stark was attracted to ethanol-infused bolts indicating it may attack trees emitting ethanol. Bolts attracted fewer nontarget species than traps, but residual attraction was much less. The selectivity of ethanol-treated bolts for Xylosandrus species should make them useful for monitoring and screening pesticides against those species.