Spread of Polygraphus proximus in Russia: addition to the EPPO Alert List
Polygraphus proximus (Coleoptera: Scolytidae) is a bark beetle originating from Asia (Far East) which mainly feeds on Far Eastern species of firs (Abies firma, A. holophylla, A. mariesii, A. nephrolepis, A. sachalinensis). In its native range, which includes Northeastern China, Korean Peninsula, Japan and the Far East of Russia (Kurile and Sakhalin Islands, Primorye and Khabarovsk territories), P. proximus is a secondary pest attacking fresh logs and trees weakened by fires, storms, or other pests (e.g. Monochamus spp., Polygraphus poligraphus). But during the last decades the presence of P. proximus has been observed in the European part of Russia and in Siberia where it is causing tree mortality, in particular on Siberian firs (A. sibirica) in the taiga forests.
In European Russia, P. proximus was observed for the first time in 1999 on spruce (Picea abies) near St. Petersburg on the Baltic Sea coast but at that time this incursion was evaluated as a small incidental introduction. In 2006, P. proximus was detected in 5 distantly located places around Moscow infesting A. sibirica and A. balsamea trees in forest plantations along a main road (‘Kurkinskoe highway’, near Khimki, Moscow region). The insect was also found under the bark of fallen spruce trees (P. abies). Because mature beetles, larvae and pupae were observed under the bark of infested trees, it is considered that P. proximus has the capacity to multiply in the Moscow region.
In Siberia, the first occurrences of P. proximus were most probably unnoticed for a rather long period and probably took place in the mid-1990s in the Kemerovo region. In spring 2009, 2 outbreaks of P. proximus were observed in the taiga forests in the Krasnoyarsk territory (Bogotolskiy and Kozulskiy areas) in pure stands of A. sibirica (each outbreak covering approximately 3 000 ha). At first, tree crowns looked healthy but trunks were coated with drops and streams of resin exuded from beetle entrance holes and in the following autumn, all infested trees were dead with yellow crowns. In June 2009, several P. proximus adults were also caught in pheromone traps near the city of Tomsk. These traps were located in Pinus sibirica stands to monitor Ips sexdentatus populations, and P. proximus was detected in 1 location where firs were present at a low density among pine trees. In 2011, the situation of P. proximus in Russia was briefly presented to the EPPO Panel on Quarantine Pests for Forestry. In particular, it was noted that the pest is causing significant damage to fir forests in Siberia where its outbreaks now cover approximately 30 000 hectares. The Panel considered that P. proximus represented a major threat to European and Siberian fir species and recommended its addition to the EPPO Alert List.
Polygraphus proximus (Coleoptera: Scolytidae – Sakhalin-fir bark beetle)
Why: Polygraphus proximus is a bark beetle, mainly feeding on firs (Abies spp.) which has been introduced from the Far East of Russia into the Western part of Siberia and European Russia. Currently, the pest has invaded Moscow and Leningrad regions in European Russia, and several areas in Siberia (Kemerov and Tomsk regions, Krasnoyarsk Territory – covering an area of approximately 30 000 ha). In Siberia, it has caused significant damage and tree mortality in forests of Siberian fir (A. sibirica). Because P. proximus may represent a major threat to European and Siberian fir species, the EPPO Panel on Quarantine Pests for Forestry recommended that P. proximus should be included in the EPPO Alert List.
Where: Polygraphus proximus is indigenous to Asia. It is commonly found in the Far East of Russia (including the Kuril Islands), Korea Democratic Peoples’ Republic, Japan and the North-East of China. The native area of P. proximus more or less coincides with the distribution range of the Far Eastern species of Abies.
EPPO region: Russia - Central Russia (introduced - Leningrad region in 1999, Moscow region in 2006), Eastern Siberia (introduced – Krasnoyarsk), Far East (native - Khabarovsk, Primorye, Sakhalin including the Kuril islands (Iturup, Kunashir, Shikotan)), Western Siberia (introduced – Kemerovo in the mid 1990s, Tomsk in 2009).
Asia: China (North-East), Japan (Hokkaido, Honshu, Kyushu, Shikoku), Korea Democratic Peoples’ Republic, Russia (Far East).
On which plants: In Asia, the major hosts of P. proximus are Far Eastern firs: Abies nephrolepis, A. holophylla, A. mariesii, А. firma and A. sachalinensis, but it can develop in other species of Abies. In Russia, it was found in A. sibirica and A. balsamea. In its native area, other recorded hosts are pine trees (Pinus spp., including P. koraiensis), larches (Larix spp.), hemlocks (Tsuga spp.), spruces (Picea abies and P. ajanensis). For the moment, there is no data on the host status of other Abies species grown in the EPPO region (e.g. A. alba). More information would also be needed on the damage this pest may cause to other conifers recorded as hosts.
Damage: P. proximus is a bivoltine species that produces subcortical galleries. In its natural habitats, this bark beetle does not cause tree mortality, unless trees are weakened by other biotic or abiotic factors. Its biological characteristics in new habitats in Europe are yet unknown, but in invaded areas in Siberia tree mortality has been observed. The crowns of newly infested fir trees initially look healthy, but trunks are fully covered by drops and streams of oleoresin exuded from beetle entry holes. On infested firs, the crown turns light brown-red and finally yellow when the trees die. Affected firs usually die 1-2 years after infestation. After tree death, needles and bark start to fall off and typical bark beetle galleries can easily be seen. Under the bark each nest consists of two to three female galleries up to 8 cm long, horizontally oriented. Larval galleries are vertically oriented along the tree trunk and reach 7 cm in length.
In Siberia and European Russia, P. proximus is a primary pest, which can cause significant economic losses to forests. In addition to direct damage, P. proximus like other bark beetles, is associated with blue stain fungi which can cause wood discoloration and necrosis of vascular tissues. In Japan, two new Ophiostoma species were isolated from P. proximus and infested Abies trees: Ophiostoma aoshimae sp. nov. and Ophiostoma rectangulosporium sp. nov. In Russia, the presence of Ophiostoma aoshimae was recently reported on A. sibirica, probably transferred by P. proximus from its natural range into Siberian forests. Further research is needed to better understand the relationships between P. proximus and blue-stain fungi, and to evaluate the pathogenicity of these fungi in areas where the insect has been introduced.
Dissemination: Because P. proximus may be hidden in the wood and therefore difficult to detect, it may be easily transported with conifer wood and wood products moving in trade. P. proximus could be transported as larvae, pupae or adults in round wood and wooden material with bark attached. The pest has been detected in traded wood (internal movement) by the Russian NPPO. As the adults can fly, they can ensure the pest spread over short distances, but no data is available on flying distances. The pest may also be carried as a hitchhiker on planting material.
Pathway: Wood and bark, wood products, plants for planting of host plants of P. proximus from countries where the pest occurs.
Possible risks: Abies species and other conifers are economically important forest and amenity trees in the EPPO region. Before 2009, there was no documented information on P. proximus in Siberia and it was generally believed that it could not develop on A. sibirica. The observation of two large outbreaks in Siberia (now covering 30 000 ha) in the taiga forest have clearly demonstrated that P. proximus could enter into new areas and damage species other than those reported in its native range. Although the pathway of introduction of P. proximus is not known, it is supposed that it has been introduced into Siberia during the mid-1990s with wood from the Far East. The possibility that P. proximus may transfer pathogenic fungi (e.g. Ophiostoma spp.) to living trees also adds to the risk. The aggressive and invasive behaviour observed in the forests of European Russia and Siberia indicate that P. proximus has the potential to become a serious pest of firs and possibly other conifers in the EPPO region and that it is desirable to prevent its further spread.
EPPO RS 2011/216
Panel review date: -
Entry date 2011-10
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