Detecting emerald ash borers (Agrilus planipennis) using branch traps baited with 3D-printed beetle decoys

Small visual-decoy-baited traps for the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), have been researched as an alternative to current technologies, but have relied on real beetles rather than synthetic materials. We hypothesized that visual decoys created by three-dimensional (3D) printing can provide such a substitute. Branch traps displaying decoys consisting of real EAB females or 3D-printed decoys were compared to controls without decoys. Traps of the three varieties were placed on neighboring branches along with one (Z)-3-hexen-1-ol lure per tree and checked daily. Both real and 3D-printed decoys similarly increased EAB trap captures compared to controls. The numbers of both sexes were higher on the decoy-baited traps, but the increase in male captures was more pronounced. Males were also ensnared closer to the decoys than females. Daily trap–capture patterns showed sparse activity of EAB adults before June 18, 2013 followed by a peak in captures of both males and females until June 28, 2013. Beginning at approximately July 1, 2013, there was a second peak of EAB captures, which consisted almost entirely of males caught on the decoy-baited traps. The native ash borer Agrilus subcinctus was found earlier in the season and was also significantly attracted to both the real EABs and the 3D-printed decoys compared with control traps. Four purple prism traps were also deployed concurrently and captures tallied on three different days within the season. The results demonstrate efficacy of a small, inexpensive, and fully synthetic decoy-based branch trap system for EAB.