Leptocybe invasa

Leptocybe invasa

The blue gum chalcid (Leptocybe invasa; Hymenoptera: Eulophidae: Tetrastichinae) is one of the most severe invasive eucalypt pests affecting plantation forestry worldwide. Since its initial establishment overseas in the Middle East and the Mediterranean region in 2000, L. invasahas spread within a period of 10 years to all continents where eucalypts are grown.

The female lays her eggs in young shoot tips and midribs of juvenile leaves, which induces extra growths (galls) to develop around the eggs. When the eggs hatch, the maggot-like larvae feed and develop inside the gall. Fully developed larvae pupate inside the galls and emergent adults chew their way out of the gall. The adult blue gum chalcid is mainly black and about 1.4 mm long.

The blue gum chalcid (Leptocybe invasa; Hymenoptera: Eulophidae: Tetrastichinae) is one of the most severe invasive eucalypt pests affecting plantation forestry worldwide. Since its initial establishment overseas in the Middle East and the Mediterranean region in 2000, L. invasahas spread within a period of 10 years to all continents where eucalypts are grown.

The female lays her eggs in young shoot tips and midribs of juvenile leaves, which induces extra growths (galls) to develop around the eggs. When the eggs hatch, the maggot-like larvae feed and develop inside the gall. Fully developed larvae pupate inside the galls and emergent adults chew their way out of the gall. The adult blue gum chalcid is mainly black and about 1.4 mm long.

Distribution
Hosts
Damage
Monitoring
Impact
Photo Gallery
References

Distribution

Native – Australia;  Invasive – Iran, Israel, Turkey, Mediterranean Basin, sub-Sahara and South Africa, India, Thailand, Laos, Vietnam, Argentina, Brazil, Chile, Uruguay and Florida (United States).

Distribution

Native – Australia;  Invasive – Iran, Israel, Turkey, Mediterranean Basin, sub-Sahara and South Africa, India, Thailand, Laos, Vietnam, Argentina, Brazil, Chile, Uruguay and Florida (United States).

Hosts

Many Eucalyptus spp. including Eucalyptus tereticornis, E. camaldulensis, E. urophylla, E. exerta, E. botryoides, E. bridgesiana, E. globulus, E. gunnii, E. grandis, E. robusta, E. saligna, E. viminalis and Eucalyptus hybrids

Hosts

Many Eucalyptus spp. including Eucalyptus tereticornis, E. camaldulensis, E. urophylla, E. exerta, E. botryoides, E. bridgesiana, E. globulus, E. gunnii, E. grandis, E. robusta, E. saligna, E. viminalis and Eucalyptus hybrids

Damage

  • Galls form mainly on young shoots and along both sides of the midrib on juvenile leaves, but in heavy infestations egg-laying may cause galls to develop in the leaf tissue and twigs. Gall size varies.
  • Gall formation on leaves of eucalypts causes deformation in terminal shoots and leaves, and causes more rapid leaf abscission and shoots to dry out.
  • Sap oozes from the oviposition holes and galls begin to develop. The infested tissue swells, becoming pinkish and developing into a series of lumps

Damage

  • Galls form mainly on young shoots and along both sides of the midrib on juvenile leaves, but in heavy infestations egg-laying may cause galls to develop in the leaf tissue and twigs. Gall size varies.
  • Gall formation on leaves of eucalypts causes deformation in terminal shoots and leaves, and causes more rapid leaf abscission and shoots to dry out.
  • Sap oozes from the oviposition holes and galls begin to develop. The infested tissue swells, becoming pinkish and developing into a series of lumps

Monitoring

Galling is easily seen. If damage is severe within a plantation, monitoring plots should be established to determine the amount of crown damage and which section of the crown has been affected (entire, lower, middle or upper sections of the crown). Repeat regularly to determine the rate of spread of Leptocybe invasa.

Monitoring

Galling is easily seen. If damage is severe within a plantation, monitoring plots should be established to determine the amount of crown damage and which section of the crown has been affected (entire, lower, middle or upper sections of the crown). Repeat regularly to determine the rate of spread of Leptocybe invasa.

Impact

  • Severe galling causes the loss of apical dominance, growth retardation and stunting in trees.
  • Most plantations are even-age monocultures, and sometimes genetically identical. All the trees may be susceptible at the same time (e.g. when they produce growth flushes, resulting in a massive pest or disease outbreak).
  • Outbreaks may occur in nursery seedlings and plantations, particularly up to two years of age.

Impact

  • Severe galling causes the loss of apical dominance, growth retardation and stunting in trees.
  • Most plantations are even-age monocultures, and sometimes genetically identical. All the trees may be susceptible at the same time (e.g. when they produce growth flushes, resulting in a massive pest or disease outbreak).
  • Outbreaks may occur in nursery seedlings and plantations, particularly up to two years of age.

Photo Gallery

Photo Gallery