Based on this PRA, Agrilus bilineatus was added to the EPPO A2 Lists of pests recommended for regulation as quarantine pests in 2019. Measures for Castanea and Quercus plants for planting, and wood are recommended.

Main conclusions 

Entry: the pest has already been introduced in the EPPO region, and is reported from a small part of Turkey, near Istanbul. The probability of further entry was considered as high with a moderate uncertainty, the highest ratings being for host plants for planting, round wood with bark, wood chips, hogwood and processing residues bigger than 2.5 cm in two dimensions, natural spread from neighbouring countries and wood packaging material (if ISPM 15 is not applied). It should be noted that several EPPO countries (e.g. the EU countries) already have requirements associated with these pathways, which are likely to have reduced the risk of entry of the pest in these countries.

Establishment outdoors: establishment of A. bilineatus is very likely to occur in the EPPO region (with a low uncertainty) as the susceptible species Quercus robur and Q. rubra are widespread and the climate is not considered as a limiting factor. Other Quercus species and Castanea sativa are likely to also be susceptible to this pest. 

The magnitude of spread was rated moderate (mean of 1-10 km per year) with a moderate uncertainty. The pest could spread naturally and by hitchhiking on vehicles from Turkey and is likely to reach Bulgaria and neighbouring countries in the next 10 years (ie. by 2029). In addition, there may be longer ‘jumps’ with movement of wood, wood products or plants for planting, which would increase the spread. 

Impact (economic, environmental and social) is likely to be very high. Larvae can girdle the conductive tissues of host trees, potentially leading to subsequent branch and tree death. Host plants, Quercus and Castanea, are major forest and ornamental trees in the EPPO region. The uncertainty of the impact is moderate, as impact could be reduced to high if not all Quercus and Castanea species are hosts and if natural enemies provide some control. 

The EWG considered that phytosanitary measures to prevent further introductions should be recommended for all Quercus and Castanea species. 

Phytosanitary Measures to reduce the probability of entry: Risk management options are considered for host plants for planting, wood of hosts and wood chips, hogwood and processing wood material. ISPM 15 is a sufficient measure for wood packaging material. Hitchhiking also presented a risk of introduction, but no measures were defined.