25 Years in Europe: a Review of the Results and Knowledge Gaps Concerning the Rapidly Spreading Invasive Oak Lace Bug (corythucha Arcuata)

The oak lace bug (OLB, Corythucha arcuata), originally native to North America, is a rapidly spreading invasive insect in Europe. Since its first detection in Italy in 2000, it has been reported in 25 countries, with its expansion largely driven by human-mediated dispersal. OLB is a multivoltine species, and its spread is further facilitated by the fact that nearly all Eurasian deciduous oak species are potential hosts, and it can also feed on several other woody plants. As a result, OLB has the potential to occupy up to 30 million hectares of oak forests in Europe and even more in Asia. Some studies indicate that OLB has significant negative effects on oaks and associated ecosystems. It reduces photosynthetic activity in oaks, impairs seedling growth, and there are implications that it also decreases fecundity. These impacts weaken tree health and could threaten the diverse communities of herbivores dependent on oaks. OLB may also influence other ecosystem components, such as leaf litter, surface waters, and even human health. Although its population dynamics are influenced by climatic conditions, current evidence suggests that European winters do not strongly constrain its spread. Various chemical control methods and some biological control agents have been tested, but no effective and environmentally sustainable management strategy is currently available. The egg parasitoid Erythmelus klopomor is the only known specialist enemy of OLB in North America and represents a promising long-term control option. However, further research on its behavior and host range is necessary before considering its intentional introduction to Europe.