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.

Developing a European Toolbox to manage potential invasion by emerald ash borer (Agrilus planipennis) and bronze birch borer (Agrilus anxius), important pests of ash and birch

The threats posed by the buprestid beetles emerald ash borer (Agrilus planipennis Fairmaire) and bronze birch borer (Agrilus anxius Gory) have been the subject of considerable research, primarily to develop methods for detection and management of the pests. PREPSYS, a Euphresco project, has worked with collaborators globally to assess the ‘state of the art’ for the two insect pests and to identify those measures that would best prepare Europe for potential invasion by the pests, especially emerald ash borer which is now in the western part of Russia and in eastern Ukraine. Building on an excellent exchange of knowledge and discussion at the OECD-sponsored international conference held in Vienna in October 2018, the concept of a European Toolbox to increase preparedness for dealing with the pests has been developed. This includes key components including surveillance, direct intervention, use of natural enemies and increased awareness of the problems associated with the pests. Collaboration is essential in delivering and refining the European Toolbox.

EPPO perspective on Agrilus planipennis (Emerald Ash Borer) and Agrilus anxius (Bronze Birch Borer)

One of the main aims of EPPO is to help its member countries to prevent entry or spread of dangerous pests (plant quarantine). The Organization has therefore been given the task of identifying pests which may present a risk (early warning/horizon scanning), evaluating their risk for the region and making proposals on the phytosanitary measures which can be taken against them (Pest Risk Analysis). Standards are also developed, including standards on how to eradicate and control pests. In addition to the development of Standards, activities on communication and citizen science (development of guidelines on raising public awareness and the production of toolkits to use in raising awareness campaigns) have also recently been started. The EPPO Secretariat was alerted by the National Plant Protection Organization (NPPO) of Sweden in 2003, and Norway in 2010, to two potential new pests, Emerald ash borer (EAB), Agrilus planipennis (Fairmaire) and Bronze birch borer, Agrilus anxius (Gory) respectively. Because of the importance of these two pests for forest species in the EPPO region, member countries agreed that EPPO recommendations should be prepared. The different EPPO activities relevant to A. planipennis and A. anxius are presented, highlighting the challenges they currently pose to the region.

Mating Behavior and Reproductive Biology of Emerald Ash Borer (Coleoptera: Buprestidae) and Two of Its Native Congeners, the Twolined Chestnut Borer and the Bronze Birch Borer

We studied the mating behavior and reproductive biology of three members of the genus Agrilus: the bronze birch borer, Agrilus anxius Gory; the twolined chestnut borer, Agrilus bilineatus (Weber); and the emerald ash borer, Agrilus planipennis Fairmaire. All three species share a highly stereotyped mating behavior. However, the copulation duration of A. planipennis was 90% longer than that of its two congeners. Female reproductive tracts of the three species were anatomically similar, as were the spermatophores. Within the spermatophores, sperm were single in A. anxius and A. bilineatus, while in A. planipennis, sperm were bundled in groups of approximately 20 in a hyaline sheath. We found that field-caught A. anxius and A. bilineatus had higher rates of female insemination than A. planipennis. In additional studies with A. planipennis and A. anxius, we found that mating duration was related to mating success, and fecundity for A. planipennis, but not for A. anxius. For both A. planipennis and A. anxius, the spermatophore was passed to the female toward the end of the copulatory period. Sperm were found in the spermatheca immediately after copulation ended in A. planipennis and 30 min after copulation ended in A. anxius. We present possible explanations for these differences.