Bark beetle Polygraphus proximus : a new aggressive far eastern invader on Abies species in Siberia and European Russia

Polygraphus proximus Brandford (Coleoptera: Scolytidae) is a common feeder on Far Eastern firs: Abies nephrolepis, A. hollophyll, and A. sachalinensis. Its native range occupies northeastern China, Korea, Japan, Kurile and Sakhalin Islands, and the southern part of the Russian Far East (Primorskiy and Khabarovskiy Krays). The beetle attacks fresh logs and trees, weakened by fires, pathogens, or defoliation. In 1999, P. proximus was found on spruce on the western Russian border, on the Baltic Sea coast near St. Petersburg (Mandelshtam and Popovichev 2000). This finding was evaluated as a small incidental introduction. It was never repeated and eventually forgotten. After 10 years, the species was found in five distantly located places around Moscow (Chilahsayeva 2008). Beetles infested many trees of Abies sibirica and A. balsamea planted along highways. They also were found under the bark of fallen trees of spruce (Picea abies) in forest stands. Polygraphus proximus differs from other co-occurring Polygraphus species on conifers by its six-segment antenna. Other species have only five segments. In spring 2009, P. proximus was found in two locations in Krasnoyarsk Kray (Southern Siberia) in the Bogotolskiy and Kozulskiy regions. There were two outbreak areas of about 3,000 ha each in a pure Siberian fir taiga forest stand. Outbreak foci were at least 3 years old with a lot of freshly infested fir trees at the periphery of the foci. Trees crowns were visually healthy, but stems were fully covered by drops and streams of resin exuded from beetle entrance holes. In autumn, all infested trees were dead with yellow crowns. Each nest consisted of two to three female galleries up to 8 cm long, horizontally oriented on surviving trees. Larval galleries were always oriented along the tree stem and reached 7 cm in length. Adults prefer to overwinter somewhere out of stems: there were only dead beetles under the bark of freshly killed