Taxonomic name: Anoplophora chinensis (Forster, 1771)
Synonyms: Anoplophora chinensis Breuning 1944, Anoplophora malasiaca malasiaca Samuelson 1965, Anoplophora malasiaca Thomson, Anoplophora perroudi Pic 1953, Anoplophora sepulchralis Breuning 1944, Callophora afflicta Thomson 1865, Callophora luctuosa Thomson 1865, Calloplophora abbreviata Thomson 1865, Calloplophora malasiaca Thomson 1865, Calloplophora sepulcralis Thomson 1865, Cerambyx chinensis Forster 1771, Cerambyx farinosus Houttuyn 1766, Cerambyx pulchricornis Voet 1778, Cerambyx sinensis Gmelin 1790, Lamia punctator Fabricius 1777, Melanauster chinensis macularius Kojima 1950, Melanauster chinensis Matsumura 1908, Melanauster chinensis var. macularia Bates 1873, Melanauster chinensis var. macularis Matsushita 1933, Melanauster chinensis var. Sekimacularius Seki 1946, Melanauster chinensis Forster, Melanauster macularius Kolbe 1886, Melanauster malasiacus Aurivillius 1922, Melanauster perroudi Pic 1953
Common names: black and white citrus longhorn (English), capricorne á points blancs (French), citrus longhorn beetle (English), citrus longhorned beetle (English), citrus root cerambycid (English), CLHB (English), gomadara-kamikiri (Japanese), hosi-kamikiri (Japanese), mulberry long-horned beetle (English), mulberry white spotted longicorn (English), Sky ox beetle (English), Starry night sky beetle (English), white spotted citrus longhorned beetle (English), white spotted longicorn beetle (English)
Organism type: insect
Both the citrus and Asian longhorn beetles originate from Eastern Asia where they seriously damage forest and agricultural plant hosts; both pose a potential economic and ecological threat to urban and natural environments where they are introduced in North America and Europe. Phytosanitary standards and regulations are the basis for preventative management to avoid unintentional international movement of such plant pests.
The eggs are 5.5 millimeters by 1.7 millimeters, elongate, sub-cylindrical, smooth-surfaced, and tapering at both ends; initially creamy white, they turn yellowish-brown when ready to hatch (Lieu 1945, in Gyeltshen and Hodges 2005). Larvae are typical round-headed woodborers. The legless grubs are 5 millimeters long at the time of hatching and grow to a size of 52 millimeters. They are a creamy white with some yellow/amber chitinzed patterns on the prothorax and a brown mark on the front side (Gyeltshen and Hodges 2005; MAF 2005). The pupa is 27 to 38 millimeters long; it has elytra that only partially covers the membranous hind wings and curves around to the ventral surface of the body (Gyeltshen and Hodges 2005).
The adult citrus longhorn has a typical cerambycid beetle body shape. Females are larger than males; the male is 25 millimeters long and the female is 35 millimeters long. The beetle is glossy black to blue-black (following emergence from the tree) and finely punctuated (bearing tiny dots or points) with a series of irregular white hair spots on the elytra (EPPO Undated; Walker 2008). (The elytra is a modified, hardened forewing of certain insect orders, notably beetles). The elytra of females is parallel whereas the elytra of males is distally tapered (Walker 2008). The antennae have 11 segments, the joints of the antennae are black with a blue-grey base; this gives them a striped appearance. The antennae are longer than the body (1.7 to 2 times the body-length in males and 1.2 times the body-length in females) (Walker 2008). The pronotum has a prominent pointed process on both sides. (The pronotum is the upper surface of the prothorax; the shape of the pronotum is often important in identification of beetles.)
Detection of any cerambycid beetle suspected to be Anoplophora is cause for concern. Positive identification of A. chinensis is made from the adult stage. The tubercles on the base of the elytra are an important identification characteristic, however, positive identification is best left to a expert cerambycid taxonomist (NAFC 2001).
These beetles spend most of their life (one to two years) as larvae inside a trunk or root. Up to 90% of the A. chinensis population may be below ground level (Herald et al 2006). There may be little or no signs of their presence. This pest is most likely to be seen in July and August, but interceptions have occurred as early as May and as late as October (Ministry for resources and Rural Affairs Malta undated).
Characteristic signs of A. chinensis in the field include: 1) Emergence holes: At the end of the pupal stage adults emerge leaving a distinct round or slightly oval shaped exit hole on the bark surface (EPPO 2007; NAFC 2001). Holes are typically 6 to 11 millimeters in diameter (Ministry for resources and Rural Affairs Malta Undated). One study found that holes are usually located on the base of the trunk between five and 20 centimeters from the ground (Jucker et al. 2006).
2) Piles of sawdust : Frass is often left at the base of trees or branches as beetles emerge from holes in summer (MAF 2005). Sawdust or frass forms an average of 29 days following oviposition/egg-laying (Jucker et al. 2006).
3) Sap oozing: In some host-plants (often in Platanus sp.) sap may ooze from the A. chinensis galleries (EPPO 2007).
Characteristic signs of A. chinensis in bonsai trees include (USDA APHIS n.d., in NAFC 2001): Scraped sections of bark; Chewed leaves; T-shaped slits cut in the bark where females deposit eggs; and Sawdust-like frass (wood-pulp) around small holes (larval tunnels) in the wood (found under loose or thin bark).
agricultural areas, host, natural forests, planted forests, urban areas
This insect finds suitable host plants in forest, urban and fruit producing areas (NAFC 2001). The citrus longhorn beetle is not exclusive to citrus orchards but may infest a great variety of fruit and nut trees as well as forestry plantations and horticultural plants.
The genera Anoplophora consists of xylophagous wood-boring bark and longhorned beetles which bore through and damage the xylem vessels of woody plants (xylem transports water and minerals throughout the tree). Anoplophora mainly infests weakened, dying or dead trees but, unlike many other borer pests, the citrus longhorn may also attack healthy trees (Chambers 2002, in Gyeltshen and Hodges 2005; Forest Research Institute 2007). Please see NUTRITION subheading on this page for a list of host plants.
The citrus longhorn damages different parts of the plant during different stages of the life-cycle. Adults feed on the tender bark of small twigs and branches and sometimes on the leaf petioles (stalks); this causes young shoots and branches to die (Maspero et al. Undated; Jucker et al 2006; EPPO 2007). The female chews through the bark of the host tree to the cambial layer, forming ‘egg scars’ (Lingafelter & Hoebeke, 2002, in Maspero et al. Undated). The larvae feed and develop in the wood of the main roots and trunks, within which they excavate tunnels; when larval density is high, infested trees can die or fall down. (Maspero et al>. Undated). Damage by larvae and beetle stages leaves the tree vulnerable to secondary pests and diseases; for example, fungi and other insects produce secondary infections or infestations in the exit holes and larval galleries (EPPO 2007).
Impacts in native range: A. chinensis originates from Eastern Asia and is a serious pest of citrus and other ornamental and forest species in Japan, Korea and China (Adachi 1994, in Delvare et al. 2004; Jucker et al. 2006; NPPO 2008). In lowland China the species is one of the most destructive cerambycid pests of fruit orchards, especially citrus; economic losses are substantial (NPPO 2008). The citrus longhorn causes serious damages to many deciduous trees in the genera Populus, Acer and Salix in Eastern Asia (Delvare et al. 2004). It also attacks Aesculus hippocastanum, and species of Betulus, Fraxinus, Morus, Pyrus and Robinia.
Impacts in alien range: In its introduced range in Europe A. chinensis poses an economic and ecological threat to horticulture, forestry and woodland trees in the UK and to citrus production in the Mediterranean (DEFRA 2008).
In the United States the citrus longhorn has the potential to become a significant pest of forests and native forest ecosystems (NPPO 2008). The citrus longhorn beetle has been given a relative Risk Rating of “Very High Risk” by the North American Forest Commission and its broad host range suggests that it would easily adapt to trees indigenous to North America (NAFC 2001). This insect has been recorded on a wide variety of fruit and nut trees including pecan, Carya illinoensis, and possibly other Carya spp., Juglans spp. (walnut) and other nut producing trees (NAFC 2001). By reducing the numbers of nut-producing trees the citrus longhorn may have a significant and negative impact on the ecosystem, in particular on fauna that depend on these mast-producing trees (NAFC 2001). The impact on fruit and nut trees also poses a significant concern to these agricultural industries (NAFC 2001).
Costs of eradication: Between 1996 and 2001, control of a related species - the Asian longhorn beetle - cost the United States over five million dollars (NAFC 2001). Eradication costs for the citrus longhorn and the overall potential impact on the citrus and other agricultural sectors translate to similar if not greater costs.
Anoplophora malasiaca (Forster) and A. chinensis (Thomson) cover one single species of harmful organism (Commission Of The European Communities 2008).
The natural range of the beetle includes China, Japan and other countries in South East Asia (China, Japan, South-Korea, North Korea, Vietnam, Taiwan, Indonesia, the Philippines, Malaysia, USA (Hawaii) and Myanmar) (DEFRA 2008).
Introduction pathways to new locations
For ornamental purposes: Findings from the study “Relative importance of the different categories of commodities associated with interceptions of alien forest insects in Europe from 1995 to 2004” showed that the trade of bonsais plays a significant role in moving alien insects around the European Community. It is responsible for 35.3% of the total number of interceptions. The bonsai trade is responsible for the introduction of at least one major tree pest in France, Italy and USA in recent years, namely, the citrus longhorned beetle (Hérard et al. 2005, in Forest Research Institute 2007).
Larvae and mature insects of A. chinensis have entered Germany and the Netherlands on bonsai plants of Acer buergeranum, A. palmatum, Celastrus, Cydonia sinensis, Malus micromalus and Sageretia from China and Japan (Anon., 1986, 1988) and have been found in unheated glasshouses and even out of doors, damaging trees and shrubs in summer (EPPO undated).
Forestry: The insect could be transported in wood products including logs, lumber, wooden packing materials, pallets or dunnage (NAFC 2001).
Nursery trade: International trade in nursery stock is considered a high risk pathway for the spread of plant pests (Forest Research Institute 2007). Regulated plants in the European Community under recent (2008) emergency directives include: Acer spp., Aesculus hippocastanum, Alnus spp., Betula spp., Carpinus spp., Citrus spp., Corylus spp., Cotoneaster spp., Fagus spp., Lagerstroemia spp., Malus spp., Platanus spp., Populus spp., Prunus spp., Pyrus spp., Salix spp., and Ulmus spp. All consignments carrying these plant species are high-risk in terms of their potential for carrying A. chinensis individuals or infestations (Commission Of The European Communities 2008).
Solid wood packing material: High risk goods associated with the transfer of insect pests include consignments of stones, cast iron or electronic goods imported from Asia (Krehan 2002).
Transportation of habitat material: The larvae may move in felled timber and in nursery stock. In bonsai, they are more often found in field-collected plants than those grown under supervised nursery conditions (NPPO 2008).
Local dispersal methods
Natural dispersal (local): The insect is a relatively strong flier capable of traveling several kilometers. While adults are strong fliers, females, heavily laden with eggs, tend to prefer to oviposit either on trees from which they emerged or within a close proximity (NAFC 2001).
Larvae tunnel through and obtain nutrition from woody portions of the plant. Adult longhorn beetles feed on the bark, leaves and leaf petioles of the host plant (NAFC 2001). A. chinensis is a polyphagous longhorn beetle feeding on many different kinds of food and plant species. The citrus longhorned beetle has been recorded on over a 100 recorded species (Lingafelter and Hoebeke 2002). Many of these are important species in the arborculture, forestry and agricultural industries. A. chinensis may infest species in the following plant families (Lingafelter and Hoebeke 2002, in NAFC 2001): Aceraceae (maple), Anacardiaceae, Araliaceae, Betulaceae (birch), Eleangaceae, Fagaceae (beech, chestnut, oak), Lauraceae (laurel), Oleaceae (ash), Polygonaceae, Styracaceae, Rutaceae, Rosaceae, Salicaceae (poplar and willow), Ulmaceae (elm), Moraceae (mulberry), Meliaceae, Leguminosae, Juglandaceae (walnut), Aquifoliaceae, Platanaceae (sycamore), Euphorbiaceae, Casuarinaceae, Verbenaceae , Sapindaceae, Theaceae and Taxodiaceae (yew).
According to NPPO (2008) the primary hosts of A. chinensis are: lime Citrus aurantiifolia, sour orange C. aurantium, mandarin lime C. limonia, pummelo C. maxima, tangerine C. nobilis, and navel orange C. sinensis
The range of host plants appears to be even wider in A. chinensis than in the Asian longhorn A. glabripennis (Herald et al 2006). Other hosts include (NPPO 2008; Lingafelter and Hoebeke 2002, in NAFC 2001): apple Malus pumila, Australian pine or beefwood-tree Casuarina equisetifolia and Casuarina stricta, cherry Prunus spp. , China-berry or Indian lilac Melia azedarach, Chinese pear leaved crabapple Malus spectabilis, fig Ficus spp. , guava Psidium guajava, hibiscus Hibiscus spp., Japanese red cedar Cryptomeria japonica, jujube Ziziphus jujube, litchi Litchi sinensis, oval kumquat Fortunella margarita, paper mulberry Broussonetia papyrifera, Persian walnut Juglans regia, peach Prunus persica, pecan Carya illinoinensis, pear Pyrus communis, pigeon pea Cajanus cajan, plum Prunus spp., poplar or aspen Populus spp., sycamore or plane tree Platanus spp., tea Camellia sinenesis, white mulberry Morus alba, and willow Salix sp.
Egg-laying starts about 12 days after the introduction of the male into the cage (Jucker et al. 2006). Another source indicates that egg-laying begins a week after copulation (EPPO undated). Under rearing conditions, Lieu (1945, in Gyeltshen and Hodges 2005) observed an average fecundity of 15 eggs laid per female, but the female is potentially able to lay a significantly larger number of eggs. In a small Italian preliminary study by Jucker and collegues (2006) 23 females laid seven to 67 eggs each (350 in total) giving an average of 15 eggs per female. Other sources indicate that each female lays about 70 eggs one by one under the bark of the trunk, from just above the soil surface to 60 cm higher (EPPO undated).
A. chinensis females lay most of their eggs around tree collars. The larvae develop downwards and many of them tunnel. 90% of the A. chinensis population is below ground level.
The citrus longhorn takes one to two years to complete its development; larvae may be present throughout the year (CABI 2004, Lieu 1945, in Gyeltshen and Hodges 2005; NAFC 2001). In a small Italian study the adults observed (in cages) lived an average of 55.6 days (Jucker et al. 2006).
Fertilised females move to the base of a tree, around the collar or on main roots, to search appropriate places to lay eggs. With its mandibles, the A. chinensis female begins making a small incision, 3-4 mm long, through the bark, transversally to the axis of the trunk or of the root. When an appropriate place has been found, the female inserts its ovipositor in the prepared incision and injects an egg perpendicularly to the incision, within the bark (more or less at one half of its thickness). Under the pressure of the ovipositor inserted within the bark, the upper layer of bark cracks so that the visible final symptom of an egg laid is a reverse T-shape crack of the bark. A single egg is deposited in each incision. At the intersection of the arms of the T-shape crack, one can see a tiny ovoid hole made during the insertion of the ovipositor. This hole is plugged with some brown secretion from the female’s abdomen. This fluid hardens on contact of air, making a stopper that closes the entrance of the egg chamber (EPPO, 2007).
A study by Jucker and collegues (2006) found that, in Italy, the highest number of ovipositions (egg-laying) per week was recorded between the end of July and mid August. The findings indicated that: (i) the maximum height of the oviposition scars on the trunk increases as the number of eggs laid on the plant increases, (ii) the eggs have a 76% probability of hatching, (iii) the hatching rate decreases as the number of eggs laid on the plant increases.
Incubation lasts 15-20 days depending on the temperature (EPPO 2007). The young larvae hatch out in one to three weeks and feed on the green, sappy portion of the inner bark. The first instar larva is around 6 millimeters in length; it chews the bark around the egg chamber and enlarges it. The second instar larva bores a gallery to the cambium layer and feeds on the latter. The third instar larva bores a gallery within the phloem and in the external layer of the xylem boring irregular tunnels deep into the woody tissue (EPPO 2007; NAFC 2001). (An instar is a developmental stage between each successive moult until sexual maturity is reached). Full-grown larvae are 50 to 60 millimeters in length (EPPO 2007).
Findings from a small North Italian study indicate that larvae overwinter at various stages of their development (depending on the time of egg laying) and resume intense feeding during spring, pupating and emerging as adults in late May-early June (EPPO 2007).
The pupal stage lasts for four to six weeks (Gyeltshen and Hodges 2005). Pupation and adult development takes place in the wood, often in the upper part of the feeding area (EPPO undated; NAFC 2001).
At the end of the pupal stage, the adults stay inside the pupal chamber for about week during which their exoskeleton hardens; adults emerge leaving a distinct round or slightly oval shaped exit hole on the bark surface (EPPO 2007; NAFC 2001). In China adults emerge from April to August, with a peak from May to July (Florida Department of Agriculture Consumer Services 2004).
Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG) with support from the Forestry Division (Council Of Agriculture) Taiwan
Last Modified: Friday, 13 February 2009