Studies on the native range of Agrilus planipennis
Studies have been recently conducted to better understand the distribution of Agrilus planipennis (Coleoptera; Buprestidae – EPPO A2 List) in its native range by carefully re-examining museum specimens and literature sources. A comprehensive database of geographical records (108 localities) could be constructed to generate a detailed map of the native range of A. planipennis. These studies also revealed that a number of records, although being repeated through the literature, were either false or ambiguous due to misidentifications, taxonomic uncertainties and unclear specimen labels. As a result, the verified native range [China (Beijing, Hebei, Heilongjiang, Jilin, Liaoning, Shandong, Tianjin, Xinjiang), Japan, Korea (Republic), Russian Far East (Primorye, Khabarovsk)] is more restricted than that which is usually described in the literature.
Russian Far East
In the Russian Far East, A. planipennis was first collected in 1935 (as A. marcopoli). Before 2004, only a few specimens were collected in 6 districts of Primorye (Chuguevka, Hasan, Lazo, Shkotovo, Spassk, Ternei). In 2004-2012, specific surveys revealed damage caused by A. planipennis on Fraxinus pennsylvanica (introduced ash species) across Primorye and in Southern Khabarovsk. Specific surveys conducted in 2010 and 2011 in ash tree plantations in Sakhalin Island did not detect A. planipennis. It is also noted that the pest has not been found in Kuril Islands.
In China, A. planipennis is not considered to be a major threat to natural ash stands or plantations but mainly attacks ornamental trees in urban environments.
- Heilongjiang: until the 1960s, A. planipennis was very rare. The first outbreak was recorded in Harbin in 1964 on F. americana (introduced ash species) and damage was observed. During surveys conducted from 2003 to 2008, A. planipennis was found in 4 prefectures on native hosts (F. mandshurica, F. chinensis var. rhynchophylla).
- Jilin: A. planipennis was recorded in at least 5 prefectures on F. mandshurica, F. chinensis var. rhynchophylla, F. pennsylvanica.
- Liaoning: A. planipennis was recorded in at least 6 prefectures on F. mandshurica, F. chinensis var. rhynchophylla and F. chinensis var. chinensis.
- Beijing: A. planipennis has been recorded since the late 19th century (Beijing is a type locality of the species) and is currently considered to be a rather common species.
- Hebei and Tianjin: A. planipennis is a rather common species on F. chinensis var. rhynchophylla and F. chinensis var. chinensis, as well as on F. velutina (introduced ash species). Interestingly, outbreaks of A. planipennis were recorded on F. velutina in Tianjin at different periods (e.g. 1982-1991, 1998-2002). During surveys conducted in 2003-2008, the pest was found at least in 6 localities in Tianjin on F. velutina and F. pennsylvanica; and outbreaks were also recorded in Hebei. It is supposed that these outbreaks of A. planipennis in Tianjin and Hebei could be the initial point of further invasion of the pest to North America and European Russia in the early 1990s.
- Shandong: the pest occurs on F. velutina in urban plantations. Considering that Shandong is the southernmost part of the Chinese distribution and that the pest is found on a non-native host, it is more likely that this area forms part of the introduced range rather than the native range.
- Xinjiang: the pest was first found in Yili valley in 2016. This record should be considered as a new introduction rather than an expansion of the pest’s native range.
- Sichuan: this record is based on a single specimen from the National Museum in Prague (CZ) labelled ‘Szechuan’ without any further details. More recent observations did not detect the pest in Sichuan nor in adjacent provinces. Considering that this area is situated more than 1000 km from the nearest documented locality of the pest, it is concluded that this single record in Sichuan is doubtful.
- Neimenggu (Inner Mongolia): despite the fact that Neimenggu is considered to be part of the native range of A. planipennis, no documented localities could be found. A specific survey conducted in 2006 did not detect the pest. Therefore, the presence of the pest in Neimenggu is considered doubtful.
A. planipennis has been recorded from the Republic of Korea at least since 1943. Specific surveys conducted from 2003 to 2008 have shown that it is widespread, although at low densities, and that it mainly feeds on F. chinensis var. rhynchophylla and F. mandshurica. Although there are no documented localities in the Korea Democratic Peoples’ Republic, it is likely that A. planipennis occurs in this country which is in the centre of the known native range.
Japanese records are based on the assumption that Agrilus marcopoli ulmi is a synonym of A. planipennis. A. marcopoli ulmi was described in 1956 from specimens collected in 1930 from Ulmus propinqua in Sapporo. In 1994, A. marcopoli ulmi was synonymized with A. planipennis on the grounds that there were no reliable morphological features to separate Japanese specimens from those collected on the Asian continent.
All records in Mongolia refer to a single locality, namely the type locality of A. marcopoli (i.e. ‘Mongol’ or ‘Chan-heou’). The exact position of this type locality remains unclear, but some authors believe that it is situated in China rather than in Mongolia. Mongolian entomologists who were consulted responded that A. planipennis has not been observed in Mongolia. Finally, Fraxinus spp. (or other members of Oleaceae) are not reported to occur in Mongolia. Therefore, it is concluded that the record of A. planipennis in Mongolia is doubtful.
It is noted that there are only two old records of A. planipennis in Taiwan: as Agrilus feretrius and A. teretrius (considered as a synonym of A. planipennis and a subspecies of A. marcopoli, respectively). Some authors have suggested that these records probably refer to another Agrilus species. In the absence of recent information, it was thus concluded that these records in Taiwan are doubtful.
The record in Laos results from a misidentification of A. tomentipennis.
Orlova-Bienkowskaja MJ, Volkovitsh MG (2018) Are native ranges of the most destructive invasive pests well known? A case study of the native range of the emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae). Biological Invasions 20(5), 1275-1286.