Dryocoetes himalayensis, a bark beetle spreading in Europe
Dryocoetes himalayensis (Coleoptera: Curculionidae: Scolytinae) is a bark beetle native to the Himalayan region. In Europe, it was first recorded from France and Switzerland in 1975 and 1980 respectively. In 2009, it was first recorded in the Czech Republic (South Moravia). It is considered established in these 3 countries. More recently, it was found in traps in Austria (2016), Germany (2016), and Slovakia (2017). In Europe, all records of this species were incidental, originating from sweeping of vegetation, beating of trees or shrubs, or from various traps.
In its region of origin, D. himalayensis is reported to breed in walnut (Juglans regia) and Sorbus lanata. Recent observations in the Czech Republic showed that D. himalayensis developed in declining black walnut trees (Juglans nigra). The galleries were in trunks of various diameters (7–45 cm) and were accompanied by dark necrotic areas and noticeable outflow of black fluid from beetle entrance holes. Further studies are necessary to clarify its potential status as a pest of walnut trees. D. himalayensis was hypothesized to be possibly also associated with oaks because it was always collected in or near oak stands in its European localities.
Sources
Foit J, Kašák J, Májek T, Knížek M, Hoch G & Steyder G (2017) First observations on the breeding ecology of invasive Dryocoetes himalayensis Strohmeyer, 1908 (Coleoptera: Curculionidae: Scolytinae) in its introduced range in Europe. Journal of Forest Science 63(6), 290–292.
Procházka J, Stejskal R, Čížek L, Hauck D & Knížek M (2018) Dryocoetes himalayensis (Coleoptera: Curculionidae: Scolytinae), a new bark beetle species for Slovakia and Austria, and its occurrence in the Czech Republic. Klapalekiana 54, 117–121.