|Yurshenko, Galina - Russian Far East Station|
|Fuester, Roger - Collaborator|
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2012
Publication Date: 4/1/2012
Publication URL: http://www.dx.doi.org/10.1603/EC11318
Citation: Duan, J.J., Yurshenko, G., Fuester, R. 2012. Occurrence of emerald ash borer (Coleoptera: Buprestidae) and biotic factors affecting its immature stages in far eastern Russia. Environmental Entomology. 41:245-254.
Interpretive Summary: The emerald ash borer (EAB) has now become a devastating forest pest in North America, killing hundreds of millions of native North American ash (Fraxinus spp.) trees since its discovery in Michigan, USA in 2002. The native range of EAB includes large areas of Northeast Asia spanning the Russian Far East, the Korean peninsula, China, Japan, and Mongolia. Field surveys were conducted from 2008 to 2011 in the Russian Far East to investigate the occurrence of EAB and natural enemies affecting its immature stages in this native region. Survey findings indicated that EAB commonly occurred in the Russian Far East on the introduced North American green ash (Fraxinus pennsylvanica) trees, and to much lesser extent on Oriental ash (F. mandshurica and F. rhynchophylla) trees. Mortality rate of EAB larvae caused by different natural enemies (woodpecker predation, host plant resistance and/or undetermined diseases, and parasitism) varied with survey time, sites and ash species. While putative plant resistance in Oriental ash species caused high mortality of EAB larvae in this region, three parasitic wasps (Spathius nsp, Atanycolus nigriventris and Tetrastichus planipennisi) were observed attacking large EAB larvae infesting North American green ash in one study area, resulting in significant levels of EAB larval parasitism (primarily by the parasitic wasp Spathius nsp.). The major parasitic wasp (Spathius nsp) could become a potential biocontrol agent for introduction to the USA for biocontrol of EAB.
Technical Abstract: Field surveys were conducted from 2008 to 2011 in southern Khabarovskiy Kray (Khabarovsk area) and Primorskiy Kray (Vladivostok area) to investigate the occurrence of the emerald ash borer (EAB), Agrilus planipennis Fairmaire, and mortality factors affecting its immature stages. Survey findings indicate that EAB commonly occurred in both Khabarovsk and Vladivostok areas on the introduced North American green ash (Fraxinus pennsylvanica Marshall) trees, and to much lesser extent on oriental ash (F. mandshurica Rupr. and F. rhynchophylla Hance) trees. In both regions, EAB densities (larvae / m2 of phloem area in Khabarovsk) were several-fold higher on green ash (11.3 to 76.7 in Khabarovsk area and 77 to 245 in Vladivostok area) than on artificially stressed Manchurian ash (2.2) or Oriental ash (10 – 59). Mortality rate of EAB larvae caused by different biotic factors (woodpecker predation, host plant resistance and/or undetermined diseases, and parasitism) varied with survey time, sites and ash species. Except for one site at one sampling time in the Khabarovsk area, low woodpecker predation of EAB larvae was observed in both study areas between 2008 and 2011. While low rates (3 – 27 percent) of EAB larval mortality caused by undetermined biotic factors were observed on green ash logs in both Khabarovsk and Vladivostok between 2009 and 2011, much higher rates (26 – 95 percent) of EAB larval mortality caused predominantly by putative plant resistance were observed in Oriental ash species in both regions. Few (less than 1 percent) parasitism of EAB larvae was observed in Khabarovsk; however, three hymenopteran parasitoids (Spathius nsp, Atanycolus nigriventris and Tetrastichus planipennisi) were observed attacking late (3rd to 4th) instars of EAB larvae in Vladivostok area, resulting in greater 63 percent EAB larval parasitism (primarily by Spathius nsp.) in two of the three study sites. Relevance of these findings to classical biological control of EAB in newly invaded regions is discussed.