Burlap-ribbon traps are effective for detecting Agrilus (Coleoptera: Buprestidae) eggs and associated parasitoids

Agrilus species (Coleoptera: Buprestidae) often oviposit in bark cracks and crevices to protect their eggs from natural enemies and unfavorable conditions, making field detection of eggs and associated parasitism challenging. Burlap-ribbon traps, which mimic tree bark texture, have been shown to induce emerald ash borer (EAB), Agrilus planipennis Fairmaire, to lay eggs on covered ash (Fraxinus sp.) surfaces. We evaluated these traps for detecting eggs of EAB and its congener bronze birch borer (Agrilus anxius Gory), as well as associated egg parasitism, using ash trees exhibiting different amounts of canopy decline and on girdled Fraxinus pennsylvanica and Betula papyrifera. Of 55 traps deployed on ash trees, 42 traps remained undisturbed, with EAB eggs recovered from 76% of those traps. Parasitized EAB eggs were detected on 21% of the undisturbed traps, with an average parasitism rate of 21%. On girdled trees, EAB eggs were recovered from traps installed on all F. pennsylvanica trees, and A. anxius eggs from traps on 3 of 5 B. papyrifera trees. Significantly more total eggs and parasitized eggs were recovered from B. papyrifera than EAB eggs from F. pennsylvanica, and parasitism rates were higher for A. anxius. These findings show that burlap-ribbon traps reliably detect Agrilus eggs and parasitoids across host species, canopy conditions, and girdling treatments, and could be a useful tool for biological control monitoring programs.