EPPO Global Database

Agrilus anxius(AGRLAX)

EPPO Datasheet

Last updated: 2019-10-18

IDENTITY

Preferred name: Agrilus anxius
Authority: Gory
Taxonomic position: Animalia: Arthropoda: Hexapoda: Insecta: Coleoptera: Buprestidae
Common names: Bronzefarbener Birken-Bohrer [German], agrile du bouleau [French], bronze birch borer [English], perceur doré du bouleau [French], Бронзовая березовая златка [Russian]
EPPO Categorization: A1 list
EU Categorization: Annex I/A1
EPPO code: AGRLAX

HOSTS 2019-07-03

Agrilus anxius is a specialist wood-borer of Betula species. In North America, primary hosts are B. papyrifera, B. populifolia. B. lenta, B. lutea, B. occidentalis, and B. alleghaniensis (Balch & Prebble, 1940; Ball & Simmons, 1980; Nielsen et al., 2011). European and Asian birch species rigorously examined thus far in North America are highly susceptible to A. anxius colonization, including B. pendula, B. pubescens, B. maximowicziana, and B. szechuanica (Ball & Simmons, 1980; Miller et al., 1991; Nielsen et al., 2011).

List: Betula albosinensis, Betula alleghaniensis, Betula dahurica, Betula ermanii, Betula lenta, Betula maximowicziana, Betula nigra, Betula occidentalis, Betula papyrifera, Betula pendula, Betula platyphylla var. japonica, Betula platyphylla var. szechuanica, Betula platyphylla, Betula populifolia, Betula pubescens, Betula utilis var. jacquemontii, Betula utilis, Betula

GEOGRAPHICAL DISTRIBUTION 2019-07-03

Agrilus anxius is endemic throughout the boreal and Northern temperate regions of North America. Its current range expands into the Southern and Western United States as a result of widespread planting of birch species as amenity trees beyond their native range (Bright, 1987; Johnson et al., 2001).

North America: Canada (Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Québec, Saskatchewan), United States of America (Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Dakota, Utah, Vermont, Washington, West Virginia, Wisconsin, Wyoming)

BIOLOGY 2019-07-03

A. anxius exhibits an annual or biennial life cycle depending on latitude, climatic conditions, and host condition (Slingerland, 1906; Balch & Prebble, 1940; Anderson, 1944; Nash et al., 1951). In Ohio and Michigan, adult emergence has been shown to begin at about 550 cumulative degree days, using a base temperature of 50°F and a starting date of January 1 (Herms, 2004), i.e. about 305 DD using a base 10°C. Adult emergence occurs over a period of 10–12 weeks, with peak emergence occurring approximately 2–4 weeks after first emergence (Akers & Nielsen, 1984). Adults (Fig. 1) are active between May and August, depending on climate (Barter, 1957; Akers & Nielsen, 1984; Loerch & Cameron, 1984; Mussey & Potter, 1997), and live for 2–5 weeks (Akers & Nielsen, 1990).

Adult feeding is obligate for survival and reproductive maturation (Barter, 1957; Akers & Nielsen, 1990). Adults can feed successfully on leaves of several species (e.g. Salix, Betula, Populus), but foliar damage is negligible (Akers & Nielsen, 1990). Females lay eggs singly or in clusters, consisting of up to 14 eggs, in bark crevices, cracks, and under loose layers of outer bark (Barter, 1957; Loerch & Cameron, 1984). Females have the potential to produce about 75 eggs in a lifetime (Barter, 1957). Egg eclosion occurs after approximately 2 weeks (Barter, 1957). Neonates bore through the outer bark into phloem tissue and complete 4 instars (Fig. 2A) (Loerch & Cameron, 1983a). Larval feeding results in formation of frass-filled galleries in the phloem and phloem-xylem interface. Galleries vary in length based on host condition and species (Fig. 2B). Larvae produce shorter galleries (approximately 25 cm) in unfavourable hosts (resistant trees) compared to their long, sinuous galleries (approximately 127 cm) in favourable hosts (more susceptible trees) (Anderson, 1944; Barter, 1957). Galleries disrupt phloem transport, which at high densities can girdle and kill trees (Barter, 1957). All instars can overwinter (Barter, 1957). However, pre-pupal larvae (4th instars that have completed feeding and constructed pupal cells) must overwinter or experience freezing temperatures for pupation to occur (Barter, 1957). Upon completion of larval development, 4th instars construct pupal cells interior to the cambial layer, generally during late summer or early autumn (Barter, 1957; Loerch & Cameron, 1984). If similar to A. planipennis, a congener to A. anxius (Petrice & Haack, 2007), 4th instars of A. anxius could persist in this non-feeding stage for extended periods of time. Pupation occurs in April–May (Loerch & Cameron, 1984). Adults emerge from the stems between May and July leaving D-shaped holes that are 3–5 mm wide (Fig. 1) (Akers & Nielsen, 1984).

Agrilus anxius colonizes most Betula species and cultivars, although host resistance varies. An intensive study suggests that A. nigra is immune to colonization (Nielsen et al., 2011). Bronze birch borer is considered a secondary invader of stressed trees (Houston, 1987), and colonization of other North American species (e.g. B. papyrifera, B. populifolia, B. lutea, B. allegheniensis) has been associated with drought, old age, insect defoliation, soil compaction, and stem or root injury (Balch & Prebble, 1944; Anderson, 1944; Barter, 1957; Jones et al., 1993). European and Asian species that have been studied are much more susceptible than North American species (Miller et al., 1991; Nielsen et al., 2011). In a 20-year common garden study in Ohio, USA, with a high number of replicates, bronze birch borer infestation caused complete mortality of Eurasian species (B. pendula, B. pubescens, B. maximowicziana, B. szechuanica), but the majority of individuals (>75%) of North American species (B. papyrifera, B. populifolia, B. nigra) were still alive at the end of the study (Nielsen et al., 2011). Drought stress is not necessary for colonization of B. pendula by A. anxius, as both irrigated and non-irrigated B. pendula trees were highly susceptible to A. anxius colonization in a controlled experiment (BK Hale and DA Herms, unpublished). Birch trees as small as 2.5 cm are colonized by A. anxius (DA Herms and DG Nielsen, pers. obs.).

In North America, A. anxius populations generally exist at endemic levels (Balch & Prebble, 1940). However, periodic outbreaks have been reported during the 20th century and have been associated with predisposing stress (Balch & Prebble, 1940; Nash et al., 1951; Houston, 1987; Jones et al., 1993). For example, following a severe drought, mortality of over 105 million birch trees was associated with an outbreak of A. anxius in the Great Lakes  region of North America (Jones et al., 1993; Minnesota DNR, 1993, 1994).

DETECTION AND IDENTIFICATION 2019-07-03

Symptoms

Trees infested with A. anxius contain at least one of the following: D-shaped holes created by emerging adults, larval galleries filled with frass at the phloem–xylem interface, or serpentine swellings or ridges visible through the bark where wound periderm (callus) has grown over galleries (Anderson, 1944; Barter, 1957). Trees infested with A. anxius may exhibit branch dieback, proceeding distally to proximally in the crown (Ball & Simmons, 1980). Branch dieback is sometimes preceded by yellow or thinning foliage.

Morphology

Eggs

The eggs of A. anxius are white to creamy, becoming more yellow as they mature (Barter, 1957). Eggs are oval in shape and approximately 1.5 mm long by 0.75 mm wide (Hutchings, 1923; Barter, 1957).

Larva

Larvae are white to creamy in colour and dorso-ventrally flat. The head is small and protracted into the wide prothorax. There are eight abdominal segments followed by two caudal segments (Barter, 1957). The final caudal segment terminates in two sclerotized tooth-like styles (urogomphi), which are characteristic of Agrilus (Slingerland, 1906). Mature larvae are 8–20 mm long and have four instars (Loerch & Cameron, 1983a).

Pupa

Pupation takes place in shallow cells excavated in the xylem interior to the cambium. Pupae are creamy-white upon molting and become increasingly darker as pupation progresses, ultimately achieving a bronze to black colour (Barter, 1957).

Adult

Adults are narrow, subcylindrical with coppery-bronze metallic colouration. They are 7–12 mm long and females are slightly larger than males (Barter, 1957). Males have ventral grooves on the first and second abdominal segments (Barter, 1957). Adult male A. anxius can be differentiated from the morphologically similar A. liragus (bronze poplar borer) by genitalia morphology. The lateral lobes of A. anxius male genitalia are less narrow apically and more bluntly pointed (Barter & Brown, 1949). Additionally, A. anxius has 22 chromosomes whereas A. liragus has 20 (Smith, 1949).

PATHWAYS FOR MOVEMENT 2019-07-03

There is no information about A. anxius adult dispersion by flight or wind. However, when tethered to a flight mill, A. planipennis, a similarly sized congener to A. anxius, flies on average 1.3 km per day and can exceed 7 km per day (Taylor et al., 2010). Agrilus spp. can also be transported by movement of infested plants or wood products, including dunnage, crates, pallets, wood chips, lumber and firewood (Haack, 2006). In particular, non-sanitized wood-packing material constructed from recently cut trees can frequently harbour wood-boring insects (Haack, 2006). The non- feeding pre-pupal and pupal stages of Agrilus can survive for up to 2 years in cut firewood (Petrice & Haack, 2007). A potential pathway for movement of A. anxius into Europe is the importation of woodchips from North America for biofuel. Large volumes of deciduous wood chips, which include material from Betula spp., are imported and stored outdoors in close proximity to susceptible birch species (Kopinga et al., 2010).

PEST SIGNIFICANCE 2019-07-03

Economic impact

In North America, A. anxius is the most serious pest of birch trees in both forest and amenity plantings (Barter, 1957; Ball & Simmons, 1980). In urban landscapes, A. anxius has caused widespread mortality of ornamental and street trees. In the Northern hardwood and boreal forests of North America, periodic outbreaks of A. anxius have also led to widespread mortality of birch, causing negative impacts on community composition and wildlife (Balch & Prebble, 1944; Nash et al., 1951; Millers et al., 1989; Jones et al., 1993).

Betula spp. exist throughout most of Europe but are most dominant in temperate and boreal forests of Northern Europe (Hulte´n & Fries, 1986). In Northern Europe, birch are the most important commercial broadleaved species (Hynynen et al., 2010), and depending on species, are used for pulpwood, fuel wood, lumber, plywood, and as amenity trees.

Control

Control and detection of this type of wood-boring insect is difficult. There are several insecticides (e.g. azadiractin, bifenthrin, dicrotophos, dimethoate, dinotefuran, emamectin benzoate, imidacloprid, permethrin) that have been shown to control Agrilus spp. to varying degrees (Appleby et al., 1973; Petrice & Haack, 2006; Herms et al., 2009; McKenzie et al., 2010; Smitley et al., 2010). They may be used in nurseries or on ornamental birch trees. Depending on the label, they can be applied as soil drenches, soil injections, trunk injections, lower trunk sprays, or cover sprays on the trunk, branches and foliage (Herms et al., 2009).

Trees infested with buprestids can be removed and then chipped ⁄ ground or heat-treated to kill larvae and pupae (McCullough et al., 2007). However, there are uncertainties about the maximum size of wood chips that will guarantee absence of larvae and pupae (McCullough et al., 2007; Kopinga et al., 2010). Additionally, the efficacy of heat-treatment in killing larvae and pupae of wood-boring insects depends on the amount of bark retained on logs (Haack & Petrice, 2009), the type of heat used (e.g. dry heat vs. steam heat) (Nzokou et al., 2008; Myers et al., 2009), and the intensity and duration of heat (Myers et al., 2009; Goebel et al., 2010).

 A rich suite of natural enemies to A. anxius exists in North America (Nash et al., 1951; Barter, 1957; Loerch & Cameron, 1983b). Although natural enemies have caused substantial mortality to North American populations of A. anxius in some cases (>50% of egg or larval mortality: Nash et al., 1951; Barter, 1957; Loerch & Cameron, 1983b), there are no studies of their effects on population dynamics and their ability to regulate populations of A. anxius in North America.

Phytosanitary risk

The wide geographical distribution of A. anxius in North America, from Northern Canada to the Southern United States, indicates that A. anxius can tolerate a wide range of climatic conditions, and could be physiologically pre-adapted to establish throughout much of the EPPO region. Birch species exist throughout most of Europe and Asia. Some species, such as A. pendula and B. pubescens, dominate stands in Northern Europe. For example, in Nordic and Baltic countries, birch species comprise from 11–16% and 17–28%, respectively, of the total volume of growing stock (Hynynen et al., 2010). Considering the high susceptibility of European Betula spp. to A. anxius (Nielsen et al., 2011), the introduction and establishment of this beetle may be expected to result in outbreaks and widespread mortality of Betula in forests, nurseries, and cities throughout Eurasia. If it were to be introduced and establish, A. anxius could threaten to extirpate European Betula spp. on a continental scale, just as the establishment and spread of A. planipennis in North America threatens the survival of Fraxinus spp in North America (Poland & McCullough, 2006).

PHYTOSANITARY MEASURES 2019-07-03

A. anxius was added in 2011 to the EPPO A1 List of pests recommended for regulation, and EPPO member countries are thus recommended to regulate it as a quarantine pest. Suggested phytosanitary measures are specified in the PRA performed by EPPO in 2010; they are as follows.

Plants for planting of Betula should originate from countries found free from the pest or be a small diameter (<2 cm). Alternatively they may be grown under insect-proof conditions.

Betula wood commodities should originate from countries found free from the pest or undergo heat treatment, chemical treatment, irradiation, chipping, or grinding. Alternatively they may be stored in the country of export for an appropriate period (1 year for wood chips, 2 years for wood).

REFERENCES 2019-07-03

Akers RC & Nielsen DG (1984) Predicting Agrilus anxius Gory (Coleoptera: Buprestidae) adult emergence by heat unit accumulation. Journal of Economic Entomology 77, 1459–1463.

Akers RC & Nielsen DG (1990) Reproductive-biology of the bronze birch borer (Coleoptera: Buprestidae) on selected trees. Journal of Entomological Science 25, 196–203.

Anderson RF (1944) The relation between host condition and attacks by the bronzed birch borer. Journal of Economic Entomology 37, 588–596.

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

Balch RE & Prebble JS (1940) The bronze birch borer and its relation to the dying of birch in new brunswick forests. Forestry Chronicle 16, 179–201.

Ball J & Simmons G (1980) The relationship between bronze birch borer and birch dieback. Journal of Arboriculture 6, 309–314.

Barter GW (1957) Studies of the bronze birch borer, Agrilus anxius Gory, in New Brunswick. Canadian Entomologist 89, 12–36.

Barter GW & Brown WJ (1949) On the identity of Agrilus anxius Gory and some allied species (Coleoptera: Buprestidae). Canadian Entomologist 81, 245–249.

Bright DE (1987) The metallic wood-boring beetles of Canada and Alaska: Coleoptera: Buprestidae. Insects and Arachnids of Canada Handbook Series 15, 255–256.

Goebel PC, Bumgardner MS, Herms DA & Sabula A (2010) Failure to phytosanitize firewood infested with emerald ash borer (Agrilus planipennis) in a small dry kiln using ISPM-15 standards. Journal of Economic Entomology 103, 597–602.

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

Haack RA & Petrice TR (2009) Bark- and wood-borer colonization of logs and lumber after heat treatment to ISPM 15 specifications: the role of residual bark. Journal of Economic Entomology 102, 1075–1084.

Herms DA (2004) Using degree-days and plant phenology to predict pest activity. In: IPM (Integrated Pest Management) of Midwest Landscapes (eds Krischik V & Davidson J), pp. 49–59. Minnesota Agricultural Experiment Station Publication SB-07645, 316 pp. St. Paul, MN Minnesota (US).

Herms DA, McCullough DG, Smitley DR, Sadof CS, Williamson RC & Nixon PL (2009) Insecticide options for protecting ash trees from emerald ash borer. North Central IPM Center Bulletin, 12 pp.

Houston DR (1987) Forest tree declines of past and present: current understanding. Canadian Journal of Plant Pathology 9, 349–360.

Hultén E & Fries M (1986) Atlas of North European Vascular Plants: North of the Tropic of Cancer. I. Introduction, Taxonomic Index to the Maps, 996 pp. Koeltz Scientific Books, Königstein (DE).

Hutchings CB (1923) Some biologic observations on the bronze birch borer Agrilus anxius, Gory. In: 15th Annual Report of the Quebec Society for the Protection of Plants from Insects and Fungous Diseases, pp. 89–92. The Entomological Society of Ontario, Quebec (CA).

Hynynen J, Niemistö P, Viherä-aarnio A, Brunner A, Hein S & Velling P (2010) Silviculture of birch (Betula pendula Roth and Betula pubescens Ehrh.) in northern Europe. Forestry (Oxford) 83, 103–119.

Johnson MP, Hartman JR, McNiel RE & Fountain WM (2001) Evaluation of dogwood and birch species and cultivars for resistance to key insect pests and diseases. Journal of Environmental Horticulture 19, 73–78.

Jones EA, Reed DD, Mroz GD, Liechty HO & Cattelino PJ (1993) Climate stress as a precursor to forest decline: paper birch in northern Michigan, 1985-1990. Canadian Journal of Forest Research 23, 229–233.

Kopinga J, Moraal LG, Verwer CC & Clerkx APPM (2010). Phytosanitary risks of wood chips. Alterra report 2059, pp. 88. Alterra, Wageningen (NL).

Loerch CR & Cameron EA (1983a) Determination of larval instars of the bronze birch borer, Agrilus anxius (Coleoptera: Buprestidae). Annals of the Entomological Society of America 76, 948–952.

 Loerch CR & Cameron EA (1983b) Natural enemies of immature stages of the bronze birch borer, Agrilus anxius, (Coleoptera: Buperstidae) in Pennsylvania. Environmental Entomology 12, 1798–1801.

Loerch CR & Cameron EA (1984) Within-tree distributions and seasonality of immature stages of the bronze birch borer, Agrilus anxius (Coleoptera: Buprestidae). Canadian Entomologist 116, 147–152.

McCullough DG, Poland TM, Cappaert D, Clark EL, Fraser I, Mastro V, Smith S & Pell C (2007) Effects of chipping, grinding, and heat on survival of emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), in chips. Journal of Economic Entomology 100, 1304–1315.

McKenzie N, Helson B, Thompson D, Otis G, McFarlane J, Buscarini T et al. (2010) Azadirachtin: an effective systemic insecticide for control of Agrilus planipennis (Coleoptera: Buprestidae). Journal of Economic Entomology 103, 708–717.

Miller RO, Bloese PD, Hanover JW & Haack RA (1991) Paper birch and European white birch vary in growth and resistance to bronze birch borer. Journal of the American Society for Horticultural Science 116, 580– 584.

Millers I, Shriner DS & Rizzo D (1989) History of Hardwood Decline in the Eastern United States. General Technical Report NE-126.USDA Forest Service, Northeastern Forest Experiment Station, Broomall, PA (US).

Minnesota DNR (Department of Natural Resources). (1993) Birch survey. In: Minnesota Forest Health Report 1992, pp. 67–77. Minnesota Department of Natural Resources, St. Paul, MN (US).

Minnesota DNR (Department of Natural Resources) (1994) Birch survey. In: . Minnesota Forest Health Report 1994 , pp. 9–14. Minnesota Department of Natural Resources, St. Paul, MN (US).

Mussey GJ & Potter DA (1997) Phenological correlations between flowering plants and activity of urban landscape pests in Kentucky. Journal of Economic Entomology 90, 1615–1627.

Myers SW, Fraser I & Mastro VC (2009) Evaluation of heat treatment schedules for emerald ash borer (Coleoptera: Buprestidae). Journal of Economic Entomology 102, 2048–2055.

Nash RW, Duda EJ & Gray NH (1951) Studies on Extensive Dying, Regeneration, and Management of Birch. Maine Forest Service Bulletin 15, 82 pp. Maine Forest Service, Augusta, ME (US).

Nielsen DG, Muilenburg VL & Herms DA (2011) Comparative resistance of Asian, European, and North American birch (Betula) spp. to bronze birch borer (Coleoptera: Buprestidae). Environmental Entomology 40, 648– 653.

Nzokou P, Tourteilot S & Kamdem DP (2008) Kiln and microwave heat treatment of logs infested by the emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae). Forest Products Journal 58, 68–72. 

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.

Poland TM & McCullough DG (2006) Emerald ash borer: invasion of the urban forest and the threat to North America’s ash resource. Journal of Forestry 104, 118–124.

Slingerland MV (1906) The bronze birch borer. Cornell Agricultural Experimental Station Bulletin 234, 63–78.

Smith SG (1949) Evolutionary changes in the sex chromosomes of Coleoptera. I. Wood borers of the genus Agrilus. Evolution 3, 344–357.

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, 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, 128–148.

ACKNOWLEDGEMENTS 2019-07-03

This datasheet was prepared by VL Muilenburg and DA Herms, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, USA.

How to cite this datasheet?

EPPO (2019) Agrilus anxius. EPPO datasheets on pests recommended for regulation. Available online. https://gd.eppo.int

Datasheet history 2019-07-03

This datasheet was first published in the EPPO Bulletin in 2011 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 (2011) Agrilus anxius. Datasheets on pests recommended for regulation. EPPO Bulletin 41(3), 409-413. https://doi.org/10.1111/j.1365-2338.2011.02510.x