Species characterization and responses of subcortical insects to trap‐logs and ethanol in a hardwood biomass plantation

We characterized subcortical insect assemblages in economically important eastern cottonwood ( P opulus deltoides B artr.), sycamore ( P latanus occidentalis L .) and sweetgum ( L iquidambar styraciflua L .) plantations in the southeastern U.S.A . Furthermore, we compared insect responses between freshly‐cut plant material by placing traps directly over cut hardwood logs (trap‐logs), traps baited with ethanol lures and unbaited (control) traps. We captured a total of 15 506 insects representing 127 species in four families in 2011 and 2013. Approximately 9% and 62% of total species and individuals, respectively, and 23% and 79% of total S colytinae species and individuals, respectively, were non‐native to N orth A merica. We captured more S colytinae using cottonwood trap‐logs compared with control traps in both years, although this was the case with sycamore and sweetgum only in 2013. More woodborers were captured using cottonwood and sweetgum trap‐logs compared with control traps in both years, although only with sycamore in 2013. Ethanol was an effective lure for capturing non‐native S colytinae; however, not all non‐native species were captured using ethanol lures. Ambrosiophilus atratus ( E ichhoff) and H ypothenemus crudiae ( P anzer) were captured with both trap‐logs and control traps, whereas C occotrypes distinctus ( M otschulsky) and X yleborus glabratus E ichhoff were only captured on trap‐logs. Indicator species analysis revealed that certain scolytines [e.g. C nestus mutilatus ( B landford) and X ylosandrus crassiusculus ( M otschulsky)] showed significant associations with trap‐logs or ethanol baits in poplar or sweetgum trap‐logs. In general, the species composition of subcortical insects, especially woodboring insects, was distinct among the three tree species and between those associated with trap‐logs and control traps.