Improving trapping methods for buprestid beetles to enhance monitoring of native and invasive species

Most of the current understanding of the orientation and communication of jewel beetles arose from research on the Asian emerald ash borer (EAB), Agrilus planipennis, which has become one of the most destructive invasive forest insect pests in history following its introduction to North America and European Russia. From a European perspective, a number of jewel beetles have a high invasive risk similar to that of the emerald ash borer, including the potential threat of the bronze birch borer Agrilus anxius, the goldspotted oak borer Agrilus auroguttatus, and the twolined chestnut borer Agrilus bilineatus. Native jewel beetles expanding their geographic range include the cypress jewel beetle Ovalisia festiva and the black-banded oak borer Coraebus florentinus. Other native species are increasing in their importance, including the flathead oak borer Coraebus undatus, the two-spotted oak borer Agrilus biguttatus, the flatheaded beech borer Agrilus viridis and Agrilus cuprescens. Commonly used prism and multi-funnel trap designs and other promising experimental trap designs have been tested and compared in the US and in Europe. One factor considered has been colouration, typically purple and green. Another is olfactory attraction, both to plant volatiles and extracts such as (Z)-3-hexenol, Manuka oil, Phoebe oil and Cubeb oil, and also to pheromones such as (Z)-3-lactone, for emerald ash borer. Field observations have been made of mating and host-finding behaviours of oak buprestids based upon visual stimuli in North America and Europe. By using pinned dead EAB models, visual mating approaches have been observed by males of Agrilus biguttatus, Agrilus sulcicollis and Agrilus angustulus, which is a behaviour similar to that previously observed in EAB. Green plastic-covered branch-traps significantly out-performed other trap designs and caught more Agrilus jewel beetles if an artificial visual decoy that copies a beetle body was included. A higher fidelity decoy offered the same distinctive light-scattering pattern as real resting EAB females and elicited the full sequence of stereotypical male mating flight behaviour of EAB and A. biguttatus from up to 1 m away. An optimization of visual, olfactory and other possible stimuli has likely not yet been achieved. More sophisticated trap designs could lead to more sensitive detection capabilities with increased selectivity.