Preferred name: Agrilus fleischeri
Authority: Obenberger
Taxonomic position: Animalia: Arthropoda: Hexapoda: Insecta: Coleoptera: Buprestidae
Other scientific names: Agrilus fleischeri kurosawai Obenberger, Agrilus fleischeri nipponicola Kurosawa, Agrilus fleischeri var. coreicus Kurosawa, Agrilus kochi Théry, Agrilus tscherepanovi Stepanov
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EPPO Categorization: A2 list, Alert list (formerly)
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EPPO Code: AGRLFL

Agrilus fleischeri infests poplars and willows as a cambial-feeding insect pest. In East Asia, primary hosts include Populus tremula (Eurasian aspen), P. tremula var. davidiana (Korean aspen), P. laurifolia (laurel-leaf poplar) and P. nigra var. italica (Lombardy poplar). In the literature, Salix spp. (willows) are recorded as hosts but no data on damage has been reported. Records of A. fleischeri on Quercus spp. are considered erroneous (Jendek & Grebennikov, 2011). In China, P. tremula var. davidiana (native to China) and P. nigra var. italica (non-native to China) are two common poplar species used in plantations. A field study conducted in Liaoning province has shown that the non-native P. nigra var. italica was more vulnerable to A. fleischeri than the native P. tremula var. davidiana (Zang et al., 2017a).

Host list: Populus davidiana, Populus laurifolia, Populus nigra var. italica, Populus sieboldii, Populus, Salix schwerinii

A. fleischeri was found infesting P. nigra var. italica in Saima Township, Fengcheng City, Liaoning Province, China in 2013 (Wang, pers. obs.), as well as artificially girdled P. tremula var. davidiana in 2015 at the same site (Zang et al., 2017b; Yao et al., 2018).

EPPO Region: Kazakhstan, Russia (Eastern Siberia, Far East, Western Siberia)
Asia: China (Beijing, Hebei, Heilongjiang, Jilin, Liaoning, Shaanxi, Sichuan, Tianjin), Japan (Hokkaido, Honshu), Kazakhstan, Korea Dem. People's Republic, Korea, Republic, Mongolia

In China, A. fleischeri typically has one generation per year on P. nigra var. italica, although most individuals require 2 years on P. tremula var. davidiana to complete their life cycle. 

In Liaoning province, adult emergence begins in late May, peaks in early June, and ends in early June to mid-August. The average longevity of adults is 34 days. The emerged adult leaves a distinct D-shaped exit hole on the trunk, which is on average 3 mm in length and 2 mm in width. During the early stages of adult emergence, the number of emerged males is higher than the number of emerged females, while the reverse is true afterwards.

Adults consume poplar leaves for about 7 days before mating and females feed on the margins of poplar leaves for another week prior to oviposition. In experimental conditions females produced an average of 218 eggs throughout their lifespan.

Eggs are laid either together or individually within bark cracks and crevices or beneath bark flakes. Eggs are first observed in early June, peaking in July and then declining in mid-August. Eggs usually hatch after approximately 12 days.

Newly hatched larvae bore directly into the bark until reaching the cambium where they feed, producing serpentine galleries under the bark. The early-instar larvae feed on the cambium and xylem from mid-June through to late September. The late-instar larvae excavate pupal chambers in the outer sapwood beginning in mid-August, then overwinter as J-shaped mature larvae and pupate in early May the next year. Transformation from pupa to adult takes about 26 days in experimental conditions at 23°C and 69% relative humidity (Zang et al., 2017b).

No identification key or molecular methods (no sequences are recorded in GenBank) for identifying this pest are currently available. Distinguishing A. fleischeri from the European species A. ater is difficult.

Symptoms

Signs and symptoms on trees infested with A. fleischeri include D-shaped exit holes created by emerged adults, serpentine larval galleries filled with fine frass under the bark, yellow foliage, dying branches, dieback and mortality of trees. The bark of P. tremula var. davidiana is smooth but becomes dark brown and cracks vertically after infestation, while the bark of P. nigra var. italica is relatively rough and there is no obvious cracking of the bark in response to larval feeding. It is difficult to detect the pest when it is present at low populations or during the early stages of infestation. Signs of adult feeding on the margins of the leaves may be noticeable in mass infestation.

Morphology

Eggs

Newly deposited eggs are milky white, then turn to faint yellow, and change to brown before hatching. Eggs are irregular oval in shape and approximately 1.1 mm long by 0.7 mm wide (Zang et al., 2017b).

Larvae

Mature A. fleischeri larvae are 18–40 mm long and milky white to light yellow in colour, but the mouthparts and urogomphi are dark brown. The tenth abdominal segments are pale cream and trapezoid in shape. The pronotal groove bifurcates posteriorly and the prosternal groove is entire (Zang et al., 2017b).

Pupae

Pupae are exarate and milky white at the early stage. Eyes first turn to black, and then the elytra also become black before developing to adults. Pupae are on average 11 mm long and 3 mm wide (Zang et al., 2017b).

Adults

Adults of A. fleischeri are 7.3–12.3 mm long and 1.8–3.4 mm wide, dark brown to black, glabrous, with six elytral spots. The face is green for the male and brown for the female. The antennae are serrate with 11 segments, and the kidney-shaped compound eyes are black. Females tend to be larger than males (Jendek & Grebennikov, 2011; Zang et al., 2017b).

Potential pathways for movement of A. fleischeri into Europe are the importation of ‘host plants for planting’, ‘round wood (with or without bark) and sawn wood of hosts’, ‘deciduous wood chips, hogwood, processing wood residues (except sawdust and shavings)’ as well as ‘wood packaging material (including dunnage)’, ‘bark’ and ‘cut branches’. In particular, untreated wood-packing material constructed from recently cut trees can frequently harbour wood-boring insects (Haack, 2006). Some Agrilus larvae may require 2 years to complete development, such as in cut firewood (Petrice & Haack, 2007).

There is no information about dispersal of A. fleischeri adults through actual flight or in wind-tunnel experiments. However, when tethered to a flight mill, A. planipennis, a congener to A. fleischeri and similar in size, flies on average 1.3 km/day and can exceed 7 km per day (Taylor et al., 2010).

Economic impact

Populus and Salix are widely grown for forestry, environmental or amenity purposes. Wood products from poplar trees are commonly used for paper-making, construction and medical supplies (Wang et al., 1984) as well as for furniture, flooring, plywood, packaging, matches and firewood (FAO, 2008).

A. fleischeri has been responsible for significant damage (tree mortality and decreased of wood quality) to economically important poplar trees in Liaoning, northeast China, and especially to P. nigra var. italica, which is widely found in the EPPO region (Zang et al., 2017b). However, the damage reported in Liaoning concerns only a small part of where P. nigra var. italica is grown in Northern China. Limited or no data was found on the susceptibility and/or impact for other hosts, or in other areas where it occurs (i.e. other Chinese provinces, as well as Japan, Kazakhstan, Mongolia, Russia, South Korea and North Korea).

Control

Detection of this cambial-feeding insect is difficult and few effective control methods are currently available. There are several insecticides (e.g. azadirachtin, bifenthrin, dicrotophos, dimethoate, dinotefuran, emamectin benzoate, imidacloprid and permethrin) that have been shown to control other Agrilus species to varying degrees (Appleby et al., 1973; Petrice & Haack, 2006; Smitley et al., 2010).

Biological control can be an effective approach to managing pest populations, especially for the concealed woodboring pests (Yang, 2004). Four parasitoids (Euderus fleischeri, Oobius saimaensis, Polystenus rugosus and Spathius sp.) associated with A. fleischeri have been discovered on infested P. tremula var. davidiana trees, and three species (O. fleischeri, Polystenus rugosus, and Paramblynotus sp.) on infested P. nigra var. italica trees (Yao et al., 2018). The dominant parasitoids are O. saimaensis and E. fleischeri on P. tremula var. davidiana, while O. fleischeri and Paramblynotus sp. were dominant parasitoids on P. nigra var. italica. These natural enemies play an important role in suppressing populations of A. fleischeri in natural forests of China. In addition, the high parasitism rates of these parasitoids in China suggest that they could potentially help manage this buprestid beetle if it does invade new areas (Zang et al., 2017b).

Phytosanitary risk

Poplar and willow are widely introduced and cultivated in many EPPO countries and regions because they grow quickly on a range of sites. Poplars are often planted with a low diversity of selected genotypes and poplar production can be concentrated along main rivers such as the Po in Italy or the Garonne in France. High densities of Populus spp. in broadleaved forests are found in the eastern part of the EPPO region (Russia in particular). Locally, high densities are also observed (e.g. in Norway, Finland, Belgium and the South of France).

The preference of A. fleischeri for exotic poplar trees that have been planted in the Liaoning province could indicate that European poplar species may be more susceptible, in particular P. nigra, just as A. planipennis in China threatens the exotic Fraxinus americana, F. pennsylvanica, F. excelsior and F. velutina, whereas the native F. mandshurica and F. chinensis are less affected (Liu et al., 2003, Zhao et al., 2007). The pest could establish in the EPPO region where poplar and willow are grown (with an uncertainty on the species attacked). The climatic conditions allowing the establishment of A. fleischeri are considered suitable at least where similar conditions from areas where the pest currently occurs (i.e. in the eastern part and central Europe), with more uncertainties for other EPPO regions. Existing predators of the native pests may contribute to the control of A. fleischeri.

A. fleischeri was added to the EPPO Alert List in 2018 (EPPO, 2018) and to the EPPO A2 list in 2019.

Suggested phytosanitary measures are specified in the pest risk analysis performed by EPPO in 2018 (EPPO, 2019) and are as follows. Plants for planting of Populus spp. and Salix spp. should originate from pest-free areas or pest-free sites of production under complete physical isolation, plants being packed in conditions preventing infestation during transport (or commercialized outside the period where adults are present). Round wood and sawn wood of more than 6 mm thickness of Populus spp. and Salix spp. should either originate in pest-free areas or undergo debarking followed by heat treatment, irradiation or fumigation. Alternatively, the bark may be removed with 2.5 cm of outer xylem. Bark and cut branches of Castanea spp. and Quercus spp. should originate in pest-free areas. Wood chips, hogwood and processing wood residues should originate in pest-free areas and be stored and transported under control of the NPPO to prevent contamination by adults. Wood packaging material should undergo treatment according to ISPM 15.

Appleby JE, Randell R & Rachesky S (1973) Chemical control of bronze birch borer. Journal of Economic Entomology 66(1), 258–259.

EPPO (2018) Pest Alert List: Agrilus fleischeri (Coleoptera: Buprestidae).

EPPO (2019) Document 19-25045 Pest Risk Analysis for Agrilus fleischeri. Retrieved from https://gd.eppo.int/taxon/AGRLFL/documents.

FAO (2008) Poplars, Willows and People’s Wellbeing. Synthesis of Country Progress Reports. Activities Related to Poplar and Willow Cultivation and Utilization, 2004 through 2007. Food and Agriculture Organization of the United Nations. Retrieved from http://www.fao.org/3/k3380e/k3380e00.htm [accessed on 01 Nov 2019]

Haack RA (2006) Exotic bark- and wood-boring coleoptera in the United States: recent establishments and interceptions. Canadian Journal of Forest Research 36(2), 269–288.

Jendek E (2005) Taxonomic and nomenclatural notes on the genus Agrilus Curtis (Coleoptera: Buprestidae: Agrilini). Zootaxa 1073, 1–29.

Jendek E & Grebennikov V (2011) Agrilus (Coleoptera: Buprestidae) of East Asia, pp. 362. Jan-Frakac, Prague.

Lee JG & Ahn KJ (2012) Arthropoda, Insecta, Coleoptera, Buprestidae, Agrilinae, Agrilini, Agrilus: jewel beetles, pp. 98. National Institute of Biological Resources, Ministry of Environment, Incheon Korea.

Liu H, Bauer LS, Gao R, Zhao T, Petrice TR & Haack RA (2003) Exploratory survey for the emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), and its natural enemies in China. The Great Lakes Entomologist 116, 147–152.

Petrice TR & Haack RA (2006) Efficacy of three insecticides applied to bark to control Agrilus planipennis (Coleoptera: Buprestidae). Great Lakes Entomologist 39, 27–33.

Petrice TR & Haack RA (2007) Can emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), emerge from logs two summers after infested trees are cut? Great Lakes Entomologist 40, 92–95.

Smitley DR, Doccola JJ & Cox DL (2010) Multiple-year protection of ash trees from emerald ash borer with a single trunk injection of emamectin benzoate, and single-year protection with an imidacloprid basal drench. Arboriculture & Urban Forestry 36(5), 206–211.

Taylor RAJ, Bauer LS, Poland TM & Windell KN (2010) Flight performance of Agrilus planipennis (Coleoptera: Buprestidae) on a flight mill and in free flight. Journal of Insect Behavior 23(2), 128–148.

Vladivostok Dalnauka (ed.) (2009) Insects of Lazovsky nature reserve. Russian Academy Of Sciences, Far Eastern Branch, Institute of Biology And Soil Science, Vladivostok Dalnauka, Russia.

Wang C, Tung SL & Yang CY (1984) Populus. In: Flora of China (EdsWang C & Fang CF) pp. 7–78. Science Press.

Yang ZQ (2004) Advance in biocontrol researches of the important forest insect pests with natural enemies in China. Chinese Journal of Biological Control 20(4), 221–227, (in Chinese).

Yao YX, Duan JJ, Mottern JL, Wang XY, Yang ZQ, Bauer LS & et al. (2018) Two new species of Oobius (Hymenoptera: Encyrtidae) and their phylogenetic relationship with other congeners from northeastern Asia. Canadian Entomologist 150(3), 1–14.

Zang K, Wang XY, Yang ZQ & Wei K (2017a) Differences of infestation and damage between Populus davidiana and P. nigra var. italica by Agrilus fleischeri Obenberger. Chinese. Journal of Applied Entomology 54(2), 255–264, (in Chinese).

Zang K, Wang XY, Yang ZQ, Wei K & Duan JJ (2017b) Biology and natural enemies of Agrilus fleischeri (Coleoptera: Buprestidae), a newly emerging destructive buprestid pest in Northeast China. Journal of Asia-Pacific Entomology 20(1), 47–52.

Zhao TH, Zhao WX, Gao RT, Zhang QW, Li GH & Liu XX (2007) Induced outbreaks of indigenous insect species by exotic tree species. Acta Entomologica Sinica 50(8), 826–833, (in Chinese).

This datasheet was prepared by Dr. X. Wang (Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry) and finalized after the pest risk analysis performed by EPPO in 2019 (EPPO, 2019). His valuable contribution is gratefully acknowledged.

EPPO (2024) Agrilus fleischeri. EPPO datasheets on pests recommended for regulation. https://gd.eppo.int (accessed 2024-04-24)

This datasheet was first published in the EPPO Bulletin in 2020 and is now maintained in an electronic format in the EPPO Global Database. The sections on 'Identity', ‘Hosts’, and 'Geographical distribution' are automatically updated from the database. For other sections, the date of last revision is indicated on the right.

EPPO (2020) Agrilus fleischeri. Datasheets on pests recommended for regulation. EPPO Bulletin 50(1), 166-169. https://onlinelibrary.wiley.com/doi/epdf/10.1111/epp.12642