Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Phoracantha semipunctata
(eucalyptus longhorned borer)



Phoracantha semipunctata (eucalyptus longhorned borer)


  • Last modified
  • 14 July 2018
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Natural Enemy
  • Preferred Scientific Name
  • Phoracantha semipunctata
  • Preferred Common Name
  • eucalyptus longhorned borer
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Arthropoda
  •       Subphylum: Uniramia
  •         Class: Insecta
  • Summary of Invasiveness
  • P. semipunctata has become established in virtually all regions of the world in which eucalypts have been planted. The environmental limitations of the tree and the beetle are very similar, so the beetle is capable of establishing in any place in whi...

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Phoracantha semipunctata (eucalyptus longhorned borer); adult. Museum set specimen.
CaptionPhoracantha semipunctata (eucalyptus longhorned borer); adult. Museum set specimen.
Copyright©Michal Hoskovec
Phoracantha semipunctata (eucalyptus longhorned borer); adult. Museum set specimen.
AdultPhoracantha semipunctata (eucalyptus longhorned borer); adult. Museum set specimen.©Michal Hoskovec
Phoracantha semipunctata (eucalyptus longhorned borer); adult near emergence hole on Eucalyptus grandis.
CaptionPhoracantha semipunctata (eucalyptus longhorned borer); adult near emergence hole on Eucalyptus grandis.
Copyright©Bo Långström
Phoracantha semipunctata (eucalyptus longhorned borer); adult near emergence hole on Eucalyptus grandis.
AdultPhoracantha semipunctata (eucalyptus longhorned borer); adult near emergence hole on Eucalyptus grandis.©Bo Långström
Phoracantha semipunctata (eucalyptus longhorned borer); larvae and larval galleries in Eucalyptus grandis.
TitleLarval galleries
CaptionPhoracantha semipunctata (eucalyptus longhorned borer); larvae and larval galleries in Eucalyptus grandis.
Copyright©Bo Långström
Phoracantha semipunctata (eucalyptus longhorned borer); larvae and larval galleries in Eucalyptus grandis.
Larval galleriesPhoracantha semipunctata (eucalyptus longhorned borer); larvae and larval galleries in Eucalyptus grandis.©Bo Långström
Phoracantha semipunctata (eucalyptus longhorned borer); mature larvae and larval gallery in Eucalyptus grandis.
TitleMature larvae
CaptionPhoracantha semipunctata (eucalyptus longhorned borer); mature larvae and larval gallery in Eucalyptus grandis.
Copyright©Bo Långström
Phoracantha semipunctata (eucalyptus longhorned borer); mature larvae and larval gallery in Eucalyptus grandis.
Mature larvaePhoracantha semipunctata (eucalyptus longhorned borer); mature larvae and larval gallery in Eucalyptus grandis.©Bo Långström
Phoracantha semipunctata (eucalyptus longhorned borer); damaged Eucalyptus grandis timber.
TitleDamaged timber
CaptionPhoracantha semipunctata (eucalyptus longhorned borer); damaged Eucalyptus grandis timber.
Copyright©Bo Långström
Phoracantha semipunctata (eucalyptus longhorned borer); damaged Eucalyptus grandis timber.
Damaged timberPhoracantha semipunctata (eucalyptus longhorned borer); damaged Eucalyptus grandis timber.©Bo Långström


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Preferred Scientific Name

  • Phoracantha semipunctata (Fabricius) 1775

Preferred Common Name

  • eucalyptus longhorned borer

International Common Names

  • English: blue gum borer; common eucalypt longicorn; common eucalyptus longhorn; eucalyptus borer; firewood beetle
  • Spanish: taladro del eucalipto
  • Portuguese: broca do eucalipto

Local Common Names

  • Brazil: broca do eucalipto
  • Germany: Bock(Kaefer), Eukalyptus-; Eucalyptus bockkäfer
  • Italy: tarlo dell'eucalitto

EPPO code

  • PHOASE (Phoracantha semipunctata)

Summary of Invasiveness

Top of page P. semipunctata has become established in virtually all regions of the world in which eucalypts have been planted. The environmental limitations of the tree and the beetle are very similar, so the beetle is capable of establishing in any place in which the trees are capable of growing. The mode of invasion is not clear. Dunnage may be one of the principal means of spread. Beetles pupate within chambers in the wood and, if infested trees are milled into timber that is used for packing material, the pupae can complete development in the milled wood and adult beetles can emerge at the destination of the cargo.  The movement of beetle-infested firewood is another possible and significant route of invasion. The transport of unprocessed logs infested by the beetle may serve to introduce P. semipunctata to new environments.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Uniramia
  •                 Class: Insecta
  •                     Order: Coleoptera
  •                         Family: Cerambycidae
  •                             Genus: Phoracantha
  •                                 Species: Phoracantha semipunctata


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Elongate-oval, spindle-shaped, yellowish, 2.5-3.0 mm long, laid in groups of 30-40 in a single layer.


Sub-cylindrical, somewhat flattened, typical of round-headed borers, yellowish-white, about 3 mm long at hatching and 30-40 mm long at maturity.


Exarate (i.e. the legs, wings, etc., are not secondarily attached to the body), yellowish-white.


About 22-28 mm in length. The body is shiny dark reddish-brown, and a yellowish band extends across the upper half of the elytra (the hardened forewings) with one yellow spot and a prominent spine at the end. The antennae of the females are approximately the same length as the body; those of the males are somewhat longer and heavier, with spines on segments 3-8.


Top of page A native of Australia, P. semipunctata has now spread to many parts of the world, including practically all countries where tree species of Eucalyptus have been introduced. Its presence in the EPPO region was registered for the first time in Israel in 1945 when it caused damage to the Eucalyptus reforestation areas in the coastal zone. It was found on isolated trees in Egypt in 1950 and in southern Turkey in 1959. In 1963 it was discovered in Tunisia, and within 4 years had spread throughout the country. In 1972 P. semipunctata was discovered in Algeria in an area near Tunisia. In 1969 P. semipunctata was recorded in Sardinia where it had been introduced 5 or 6 years earlier. In 1975 it was found in Sicily and in 1976 it was detected in mainland Italy. At present, the infestation extends to central and southern Italy, including the islands (Cavalcaselle, 1986).

At the end of 1980, P. semipunctata was observed for the first time in Setubal, Portugal. Starting from this site it spread to almost all Eucalyptus plantations to the south of the river Tajo. In 1981 a small focus of P. semipunctata was detected in south-west Spain where a large volume of Eucalyptus logs had been imported from Portugal. By 1983, practically all the Eucalyptus plantations in the provinces of Huelva, Sevilla and Badajoz were infested. Spread was favoured by the intense droughts of those years. The pest was first recorded in northern Spain (Cantabria) in 1990 (Reporting Service 95/158).

In addition to the countries listed, P. semipunctata occurs in Syria, Mexico, Arizona Hawaii, USA, and Minas Gerais and Rio de Janeiro, Brazil (T Paine, Department of Entomology, University of California, USA, personal communication).

See also CABI/EPPO (1998, No. 122).

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes


IsraelWidespreadCABI/EPPO, 2007; EPPO, 2014
JordanAbsent, unreliable recordEPPO, 2014
LebanonPresentCABI/EPPO, 2007; EPPO, 2014
SyriaAbsent, unreliable recordEPPO, 2014
TurkeyPresent, few occurrencesCABI/EPPO, 2007; EPPO, 2014


AlgeriaRestricted distributionCABI/EPPO, 2007; EPPO, 2014
EgyptPresentCABI/EPPO, 2007; EPPO, 2014
EthiopiaAbsent, invalid recordEPPO, 2014
LesothoPresentCABI/EPPO, 2007; EPPO, 2014
LibyaPresentCABI/EPPO, 2007; EPPO, 2014
MalawiPresentCABI/EPPO, 2007; EPPO, 2014
MauritiusPresentCABI/EPPO, 2007; EPPO, 2014
MoroccoRestricted distribution1962Haddan and Lieutier, 2002; CABI/EPPO, 2007; EPPO, 2014
MozambiquePresentCABI/EPPO, 2007; EPPO, 2014
NamibiaAbsent, unreliable recordEPPO, 2014
RéunionPresentCABI/EPPO, 2007; EPPO, 2014
Rodriguez IslandPresentCABI/EPPO, 2007
South AfricaWidespreadCABI/EPPO, 2007; EPPO, 2014
-Canary IslandsPresentCABI/EPPO, 2007; EPPO, 2014
SwazilandPresentCABI/EPPO, 2007; EPPO, 2014
TunisiaRestricted distributionCABI/EPPO, 2007; EPPO, 2014
ZambiaPresentCABI/EPPO, 2007; EPPO, 2014
ZimbabweWidespreadCABI/EPPO, 2007; EPPO, 2014

North America

MexicoAbsent, unreliable recordEPPO, 2014
USARestricted distributionCABI/EPPO, 2007; EPPO, 2014
-CaliforniaPresentCABI/EPPO, 2007; EPPO, 2014

South America

ArgentinaPresentCABI/EPPO, 2007; EPPO, 2014
BoliviaPresentCABI/EPPO, 2007; EPPO, 2014
BrazilPresentCABI/EPPO, 2007; EPPO, 2014
-BahiaPresentCABI/EPPO, 2007; EPPO, 2014
-Espirito SantoPresentCABI/EPPO, 2007; EPPO, 2014
-Minas GeraisPresentCABI/EPPO, 2007; EPPO, 2014
-ParanaPresentCABI/EPPO, 2007; EPPO, 2014
-Rio Grande do SulPresentCABI/EPPO, 2007; EPPO, 2014
-Sao PauloPresentCABI/EPPO, 2007; EPPO, 2014
ChileWidespreadCABI/EPPO, 2007; EPPO, 2014
PeruPresentCABI/EPPO, 2007; EPPO, 2014
UruguayWidespreadCABI/EPPO, 2007; EPPO, 2014


CroatiaAbsent, confirmed by surveyEPPO, 2014
CyprusRestricted distributionCABI/EPPO, 2007; EPPO, 2014
FranceRestricted distributionCABI/EPPO, 2007; EPPO, 2014
-CorsicaWidespreadCABI/EPPO, 2007; EPPO, 2014
-France (mainland)Absent, intercepted onlyCABI/EPPO, 2007
ItalyRestricted distributionCABI/EPPO, 2007; EPPO, 2014
-Italy (mainland)Restricted distributionCABI/EPPO, 2007
-SardiniaPresentCABI/EPPO, 2007; EPPO, 2014
-SicilyPresentCABI/EPPO, 2007; EPPO, 2014
MaltaPresentCABI/EPPO, 2007; EPPO, 2014
NetherlandsAbsent, formerly presentCABI/EPPO, 2007; EPPO, 2014
PortugalWidespreadIntroduced1980Way et al., 1992; CABI/EPPO, 2007; EPPO, 2014
-MadeiraPresentEPPO, 2014
-Portugal (mainland)WidespreadCABI/EPPO, 2007
SpainWidespreadIntroduced1981Martinez Egea, 1982; CABI/EPPO, 2007; EPPO, 2014
-Spain (mainland)WidespreadCABI/EPPO, 2007
SwedenAbsent, intercepted onlyCABI/EPPO, 2007; EPPO, 2014
SwitzerlandAbsent, intercepted onlyCABI/EPPO, 2007; EPPO, 2014


AustraliaWidespreadCABI/EPPO, 2007; EPPO, 2014
-Australian Northern TerritoryPresentCABI/EPPO, 2007; EPPO, 2014
-New South WalesPresentCABI/EPPO, 2007; EPPO, 2014
-QueenslandPresentCABI/EPPO, 2007; EPPO, 2014
-South AustraliaPresentCABI/EPPO, 2007; EPPO, 2014
-TasmaniaPresentCABI/EPPO, 2007; EPPO, 2014
-VictoriaPresentCABI/EPPO, 2007; EPPO, 2014
-Western AustraliaPresentCABI/EPPO, 2007; EPPO, 2014
New ZealandPresent, few occurrencesCABI/EPPO, 2007; EPPO, 2014
Papua New GuineaPresentCABI/EPPO, 2007; EPPO, 2014

History of Introduction and Spread

Top of page P. semipunctata was first reported as an introduced insect problem in South Africa in 1906. The widespread movement of the insect did not occur until the later third of the twentieth century when eucalypts were widely accepted as a major source of cellulose for paper production and plantations were established in many parts of the world with a Mediterranean climate. For example, the beetle was present in Tunisia before 1969, in Italy, Spain, Egypt, France, Portugal and Turkey by 1983, and in California, USA, by 1985.  Populations were established in South America by the early 1990s.

Risk of Introduction

Top of page P. semipunctata is an A2 quarantine pest for EPPO (OEPP/EPPO, 1983) and is also of quarantine significance for JUNAC. However, in the Mediterranean area it is a relevant quarantine pest only in countries where it has not yet been detected, e.g. Greece, Spain (northern provinces) and former Yugoslavia. It is also a quarantine pest for IAPSC.

Hosts/Species Affected

Top of page Eucalyptus species vary in susceptibility to attack under comparable drought conditions, such as those observed in Tunisia by Chararas (1969). Massive beetle attacks quickly kill Eucalyptus globulus and E. viminalis when their gum defences decline. In contrast, the gum defences of E. blakelyi continue to cause high mortality of larvae entering the bark, but some larvae survive, producing long, narrow lesions. Occasionally, a single larva girdles the trunk and kills the tree. E. cladocalyx has substantial gum defences, even during severe drought, but some larvae penetrate the bark of certain trees and produce large oval-shaped lesions exposing bare wood (Scriven et al., 1986). Under California conditions, the gum defenses do not appear to be critical in providing resistance to colonizing larvae; rather, elevated bark moisture content prevents successful penetration of the bark by first-instar larvae (Hanks et al., 1991b, 1999). El-Yousfi (1989) classified dominant tree species of Eucalyptus in Morocco according to their susceptibility to the pest. The industrial species, such as E. globulus and E. gomphocephala, were included in the most susceptible group. E. camaldulensis, E. cladocalyx and certain hybrids showed some resistance to P. semipunctata, with more than 40% of the trees of the plantations being attacked; these species were included in the moderately susceptible group. Xerophytic species, such as E. torquata, E. salmonophloia and E. brockwayi, were included in the resistant group; in these cases only scattered trees suffering light damage may be found. Similar results relating to drought tolerance in the native range with susceptibility to the borer were reported in California by Hanks et al. (1995b) with E. diversicolor, E. globulus, E. grandis, E. nitens, E. saligna and E. viminalis as more susceptible and E. camaldulensis, E. cladocalyx, E. sideroxylon and E. trabutii as more resistant. However, host susceptibility to colonization must be distinguished from host suitability for larval development. In host suitability trials, survival of larvae was highest in E. camaldulensis and E. trabutii when population densities were low and those two species attracted two to three times more adult beetles than E. cladoclayx, E. grandis or E. tereticornis (Hanks et al., 1993b). There was no difference in oviposition (determined by number of neonate larvae attempting to initiate colonization) by females offered a choice among E. maculata [Corymbia maculata], E. propinqua¸ or Angophora costata in Australia, but the larval galleries in E. maculata were significantly larger indicating a significant difference in host suitability for larval development (Paine et al., 2000a). Di Iorio (2007) lists the host plants of P. semipunctata in Argentina.

Growth Stages

Top of page Vegetative growing stage


Top of page The attacked trees show some dead branches and, in some cases, the whole crown is dead, with yellowing and wilting leaves, depending upon the intensity of the attack. The bark is easily removed, revealing the larval tunnels, which lead into the inner bark and cambium and are filled with compressed frass. These galleries are numerous and start from the same point. Usually, the larvae bore their galleries along the stem. The larvae grow as they feed and the gallery size increases correspondingly. Larvae can be seen at the end of their galleries or, if adults have already emerged, elliptical grub holes about 8-10 x 4-5 mm are evident on the bark surface.

Frequently, the gum defences of the tree cause high mortality of larvae as they enter the bark, but some larvae survive, producing characteristically long, narrow lesions with dark exudation. However, larval colonization may occur at a rate that is faster than the time required for initiation of phenolic gum resin production and trees may be killed without any visible exudation (Hanks et al., 1991b).

In logs and felled trees, the cracked and sloughing bark, larval galleries, and entrance holes into the wood are obvious symptoms of P. semipunctata infestation.

List of Symptoms/Signs

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SignLife StagesType
Leaves / yellowed or dead
Stems / gummosis or resinosis
Stems / internal feeding
Whole plant / plant dead; dieback

Biology and Ecology

Top of page Adult flight activity is in the early evening hours and both sexes are attracted to the volatiles produced by damaged or water-stressed Eucalyptus trees or cut logs that are typically good larval hosts (Hanks et al., 1993a). Males run along the bark surface and find females by antennal contact (Hanks et al., 1996a). Mating almost immediately follows antennal contact and males will guard females from mating with rival males as they search the bark for suitable oviposition sites (Hanks et al., 1996b). Males will repeatedly mate with the female he guards and oviposition occurs within a few hours of the initial contact. Adult females may live for 200 days under summer conditions and lay more than 600 eggs (Bybee, 2003). Females fed with Eucalyptus pollen lived 48-71% longer and had fecundity four to eight times higher than females fed on other pollens or sucrose solutions (Millar et al., 2003). The eggs are laid under loose bark in groups of 3-30 eggs, which incubate in 6-10 days. When the eggs hatch, the larvae may feed along the bark surface for a short distance, forming a conspicuous dark trail. They then turn into the bark and proceed towards the cambium. They feed between the inner bark and cambium until they are almost mature. As the larva matures, the gallery widens, increasing to more than three times the head width. A single larval gallery can extend for more than 1 m and can girdle a tree. When the larva is near maturity, it forms a short tunnel in the direction of the bark surface and then bores several centimetres into the wood to form a pupal chamber. The tunnel near the bark surface provides the exit for the emerging adult beetle (Scriven et al., 1986).

Egg masses are usually found during the warm season but also in small numbers during the winter. Larvae that hatch during the cold season usually die due to the accelerated drying of the bark. In Israel (Mendel, 1985), the mean minimum length of the developmental period from oviposition to the beginning of adult emergence was about 100 days for individuals that began to develop between March and July, about 215 days for the later summer brood in August-September, and about 195 days for the autumn brood in October-November. The spring developmental period of larvae averaged 80 days in fresh logs and 118 days in old, partially dried ones. The pupal period lasts 32-40 days when it begins during early spring to late summer and about 110 days when it begins in autumn. When adult emergence starts in spring or mid-summer, it is usually completed within 2-3 months, whereas when it starts from late summer onwards it lasts up to 9 months. Emergence is arrested during the winter and resumed when temperatures increase in spring (Mendel, 1985). Considering 11.5°C as the minimum threshold temperature, Gonzalez Tirado (1987) estimated the thermic integral needed to complete one generation as 1510 degree-days. One, two or three generations per year may occur in Mediterranean climates.

The developmental biology in California shows a different pattern from what was observed in Israel. It was initially thought that the beetles completed two generations each year (Hanks et al., 1993a). However, more detailed studies that involved initiating field infestations at different points during the year showed that there was only a single generation (Bybee, 2003). The adults are long-lived and are reproductively active for long periods. The continual presence of the adults and periodic events of tree mortality may partially account for the earlier incorrect interpretation of multiple generations throughout the warm parts of the year. The beetles have an obligatory winter diapause period (Hanks et al., 1991a), which appears to synchronize larval and pupal development, irrespective of when those larvae initiated their feeding. Whether larval populations were initiated in May, June or October, the resulting adults emerged the following year between early June and early August (Bybee, 2003). A small proportion of the population took 2 years to emerge as adults. Again, these individuals with prolonged development emerged during a narrow window of time between early June and early July.

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Avetianella longoi Parasite Eggs
Beauveria brongniartii Pathogen
Callibracon limbatus Parasite Larvae
Dendrocopos syriacus Predator
Jarra maculipennis Parasite Larvae
Jarra phoracantha Parasite Larvae
Linepithema humile Predator
Megalyra fasciipennis Parasite Larvae
Pheidole pallidula Predator
Platystasius transversus Parasite
Syngaster lepidus Parasite Larvae California

Notes on Natural Enemies

Top of page Several predators and parasitoids appear to cause significant mortality to beetles, larvae and eggs of P. semipunctata in Australian Eucalyptus forests. Moore (1963) observed the activity of three braconid parasitoids (Syngaster lepidus, Bracon capitator [Callibracon capitator] and Doryctes sp.), two predatory beetles, the clerid Trogodendron fasciculatum and a bothriderid Aeschyntelus vittatus. All of them may cause substantial mortality in P. semipunctata larvae. Also, the braconid parasitoids Iphiaulax rubriceps [Syngaster lepidus], Trichiohelcon phoracanthae and Acanthodoryctes morleyi [A. tomentosus] were cited (Tooke, 1928). The larval parasitoids partition their use of hosts, in part, based on bark thickness and larval size (Paine et al., 2000b; Hanks et al., 2001; Joyce et al., 2002). A detailed list of parasitoids that use Phoracantha species as hosts was compiled by Austin et al. (1994).
Tribe (2003) gives details on the introduction of A. longoi into South Africa and notes that it is more effective against P. semipunctata than P. recurva.

Means of Movement and Dispersal

Top of page The exceptional flying capacity and survival of the adult P. semipunctata are the basis of local dispersal (Hanks et al., 1998). However, the main cause of its rapid spread throughout the world has been the transport of Eucalyptus wood (Cadahía, 1980, 1983, 1986).

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Plants or parts of plantsAdults on cut flowers Yes
Containers and packaging - wood Yes

Plant Trade

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Plant parts liable to carry the pest in trade/transportPest stagesBorne internallyBorne externallyVisibility of pest or symptoms
Bark eggs Yes Pest or symptoms usually visible to the naked eye
Flowers/Inflorescences/Cones/Calyx adults Yes Pest or symptoms usually visible to the naked eye
Stems (above ground)/Shoots/Trunks/Branches adults; eggs; larvae; pupae Yes Yes Pest or symptoms usually visible to the naked eye
Wood larvae; pupae Yes Pest or symptoms usually visible to the naked eye
Plant parts not known to carry the pest in trade/transport
Fruits (inc. pods)
Growing medium accompanying plants
Seedlings/Micropropagated plants
True seeds (inc. grain)

Wood Packaging

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Wood Packaging liable to carry the pest in trade/transportTimber typeUsed as packing
Solid wood packing material with bark Eucalyptus No
Solid wood packing material without bark Eucalyptus No
Wood Packaging not known to carry the pest in trade/transport
Loose wood packing material
Processed or treated wood


Top of page In its native country, Australia, P. semipunctata occurs throughout Eucalyptus forests, but its damage is usually restricted to dead and dying trees. During severe droughts, beetle outbreaks may occur, but the populations normally appear to be limited by a complex of natural enemies, including predators and parasitoids. In the majority of other regions where P. semipunctata is found, however, tree death occurs in woodlot plantings, especially when subjected to periodic moisture stress, and includes apparently healthy trees.

In the Mediterranean basin, rapid spread of P. semipunctata was favoured by the poor state of many plantations, mainly due to drought and poor soils along with the great dispersal capacity of the beetle (Cadahía, 1986). The pest caused very serious damage to plantations in Tunisia in the years following its introduction in 1963. The first focus in Morocco was eradicated, but a later outbreak in 1981 caused an estimated loss of 2 million trees, approximately 1.18-1.47% of the area of Eucalyptus plantations (about 170,000 ha) (El-Yousfi, 1982). The average tree mortality rate in the province of Huelva in Spain, since P. semipunctata was first detected in 1981 until the end of 1983, was estimated to be between 2.23 and 3.88%, equivalent to a loss of 6207 ha, despite the high economic and labour cost of control measures (Gonzalez Tirado, 1986).

The economic impact appears to be greatest in regions of the world with Mediterranean climates. In the absence of supplemental irrigation, the hot dry summers associated with these regions potentially place the trees under moisture stress at the time of year when the beetles are most active. Although present, the beetle does not seem to be as much of a problem in parts of the world where there is abundant summer rainfall (e.g., coastal portions of eastern Australia, Hawaii, portions of Brazil).

Environmental Impact

Top of page P. semipunctata is endemic to all six biogeographic ranges in Australia. Although it kills eucalypts in its native range, it is primarily a scavenger of dead, stressed or dying trees, broken branches, or material that has been damaged by fire or other natural disturbances. The beetles can, however, cause significant mortality in areas where the trees have been introduced. There are few records of the beetle attempting to colonize non-host trees, particularly in areas where it is an introduced species. Consequently, it has little direct impact on the natural environment in these areas. Ironically, the detrimental impact of the beetles on introduced trees is perceived by some individuals or organizations as a positive environmental impact as eucalypts planted in novel geographic regions are viewed as invasive weeds.

Impact: Biodiversity

Top of page P. semipunctata colonizes only eucalypts, which are now widely planted outside their native ranges in Australia and Papua New Guinea. The beetle has very little impact on biodiversity in novel habitats because their host trees are also introduced; however, plantations of eucalyptus trees or trees that have become naturalized in the new environments have an impact on the native flora and fauna. The beetle is perceived by some individuals as a potentially beneficial insect as it causes a reduction in eucalypt populations.

Social Impact

Top of page Mortality of plantation-grown eucalypts, caused by P. semipunctata, may have a significant impact on the local economy because the beetle reduces the production of wood fibre from these plantations. This reduced economic benefit has an impact on local jobs and social welfare. In some parts of the world, eucalyptus plantations and woodlots provide grazing and firewood that benefit the local communities. Tree mortality reduces the long-term social benefit derived from these secondary uses.

Prevention and Control

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Chemical Control

Living Eucalyptus trees are not easily protected by pesticides, as the beetles' behaviour limits their exposure to the chemicals; the beetles hide during the day under loose bark and do not feed on leaves or bark. It does not appear likely that chemical control in the forest could be achieved. The adults are active during the greater part of the year and it would, therefore, be necessary to use pesticides with long residual effects or to make frequent applications to kill beetles landing on the tree. Also, viable eggs can be laid on sprayed areas before the pesticide can kill the female beetles. Eggs are usually protected from exposure to pesticides, because they are laid under layers of loose bark. Once the larvae are inside the bark, they escape pesticide applications.

Cultural Control

In Spain and Morocco silvicultural measures are used as the most effective and ecologically sound methods of control. Curative measures include clearance and felling of all attacked and dead trees, followed by their removal from the forest. Freshly cut trap logs, treated with pesticide, are placed in woodlots to attract adult beetles. Female beetles lay their eggs on the sprayed logs which are replaced every 2 weeks with fresh ones. The old logs are destroyed within 2 months to prevent beetle emergence. Recommended preventive measures are concerned with managing the forest in such a way that trees are kept in good health. Weak and declining trees should be removed. Selection of the appropriate tree species for each zone is the main preventive measure (Gonzalez Tirado, 1986; El-Yousfi, 1989).

Biological Control

The parasitoid Platystasius transversus was obtained from eggs of P. semipunctata in Morocco (Fraval and Haddan, 1988). Although described from specimens collected in Italy, the encyrtid egg parasitoid Avetianella longoi, is native to Australia and has been widely distributed around the world. It provides excellent biological control of P. semipunctata in some areas (Hanks et al., 1995a; Paine and Millar, 2002), but may contribute to the replacement of P. semipunctata by P. recurva in areas where both species have been introduced (Luhring et al., 2000).

Phytosanitary Measures

EPPO recommends that only debarked wood of Eucalyptus should be traded. It recommends also that wood of Eucalyptus (including wood chips larger than 4 x 0.5 cm) should be kept in storage under supervision for at least 6 months after debarking or must have been fumigated by an appropriate method (OEPP/EPPO, 1990). In general, dry logs older than 9 months can be considered free from larvae and pupae.


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