Trachymela

Trachymela sloanei

1. Identification

• Common name: Eucalyptus tortoise beetle
• Scientific name: Trachymela sloanei Blackburn
• Order: Coleoptera
• Family: Chrysomelidae

2. Pest description

• Beetle with an oval, convex body, generally dark brown to black.
• Adults with a rough integument and a robust appearance.
• Larvae of brownish coloration, with a soft, segmented body.
• Defoliating species, feeding mainly on young eucalyptus leaves.
• It can cause significant damage in young plantations and nurseries.

3. Main hosts

• Eucalyptus, especially Eucalyptus globulus and other cultivated species.
• Occasionally other Myrtaceae.

4. Symptoms and damage

• Partial or intense defoliation of young leaves.
• Irregular perforations and gnawed margins.
• Reduced growth in young plants.
• General weakening of the trees in repeated attacks.
• Presence of adults and larvae on the underside of the leaves.

5. Biological cycle

• Adults active during much of the year in mild climates.
• Eggs laid on the vegetation or in the soil near the host plants.
• Larvae feed on the leaves before moving to the soil for pupation.
• Development favoured by moderate temperatures.
• Several generations per year in regions with a mild climate.

6. Monitoring

• Direct observation of adults and larvae on the leaves.
• Assessment of the intensity of defoliation on young shoots.
• Regular monitoring in new plantations and nurseries.
• Recording of initial outbreaks to prevent spread.

7. Management measures

• Cultural: removal of heavily damaged plant material; maintenance of plant vigour; reduction of water stress.
• Preventive: frequent monitoring during periods of greater activity; control of nearby spontaneous host plants.
• Biological: promotion of natural enemies present in forest ecosystems.
• Integrated protection: judicious application of authorised insecticides when thresholds are reached; integration of cultural and biological measures.

Bibliographic references

• EPPO Global Database – Trachymela sloanei.
• CABI – Invasive Species Compendium – Trachymela sloanei.
• Paine, T. D. et al. (2011). Insect pests of eucalypts. Annual Review of Entomology.
• Nahrung, H. F. & Swain, A. J. (2015). Invasive insects in Australian eucalypt plantations. Australian Forestry.
• Nahrung, H. F. (2014). Ecology and management of paropsine beetles in eucalypt plantations. Forest Ecology and Management.