Asian citrus psyllid

Diaphorina citri

1. Identification

• Common name: Asian citrus psyllid
• Scientific name: Diaphorina citri Kuwayama
• Order: Hemiptera
• Family: Liviidae

2. Pest description

• Small sucking insect, 2–4 mm, brown in colour with pale spots.
• Adults keep the body tilted at about 45° when at rest.
• Flattened nymphs, yellow-orange, with waxy filaments.
• They produce honeydew and leaf deformations.
• Efficient vector of the bacterium Candidatus Liberibacter asiaticus, the agent of HLB (Asian greening), a highly destructive citrus disease.

3. Main hosts

• Citrus (orange, mandarin, lemon, lime, grapefruit).
• Ornamental Rutaceae such as Murraya spp..
• Preference for young shoots and tender leaves.

4. Symptoms and damage

• Deformations and curling of the young leaves.
• Abundant honeydew and development of sooty mould.
• Irregular sprouting and reduced vigour.
• Severe production losses in case of HLB infection.
• Extreme risk of HLB spread, an incurable disease that leads to the decline and death of the plants.

5. Biological cycle

• Several generations per year in warm climates.
• Egg-laying at the tip of young shoots.
• Nymphs develop through 5 instars.
• Adults active throughout the year in tropical and subtropical regions.
• Populations increase rapidly in spring and summer.

6. Monitoring

• Observation of nymphs and adults on young shoots.
• Checking for leaf deformations and the presence of honeydew.
• Monitoring with yellow sticky cards.
• Strict inspection in nurseries and imported plant material.
• Immediate communication to the phytosanitary authorities in case of suspicion.

7. Management measures

• Cultural: elimination of heavily attacked shoots and removal of alternative host plants.
• Biological: promotion of parasitoids such as Tamarixia radiata in regions where it is authorised.
• Integrated protection: continuous monitoring, interventions only when justified, judicious application of authorised insecticides and compliance with official containment measures.
• Official measures: compliance with DGAV and EU rules for quarantine pests, including restrictions on the movement of plants and plant material.

Bibliographic references

• EPPO Global Database – Diaphorina citri.
• CABI Invasive Species Compendium – D. citri.
• DGAV – Contingency Plan for Diaphorina citri (2015).
• DGAV – Phytosanitary updates on citrus psyllids (2019–2024).
• European Commission – Implementing Regulation (EU) 2019/2072.
• Bové, J. (2006). Huanglongbing: a destructive, newly emerging citrus disease.