Leek moth

Acrolepiopsis assectella

1. Identification

• Common name: Leek moth
• Scientific name: Acrolepiopsis assectella Zeller
• Order: Lepidoptera
• Family: Acrolepiidae

2. Pest description

• Greenish to yellowish caterpillars, with a brown head and a narrow body.
• Small adults, with greyish forewings and a characteristic dark “V”-shaped pattern.
• It mainly attacks plants of the Alliaceae family, perforating and mining leaves and pseudostems.
• A species well adapted to temperate climates, with the greatest impact on leek crops.

3. Main hosts

• Leek.
• Onion.
• Garlic.
• Shallot.
• Other species of the genus Allium spp..

4. Symptoms and damage

• Longitudinal galleries in the leaves, often visible as whitish streaks.
• Perforations and tunnels inside the pseudostem.
• Wilting and weakening of young plants.
• Reduced commercial quality due to internal damage and the entry of pathogenic agents.
• Severely attacked plants may show deformations and loss of vigour.

5. Biological cycle

• Several generations per year, depending on temperature.
• Eggs laid individually on the leaf surface.
• Caterpillars rapidly penetrate the tissues, where they feed and develop.
• Pupation occurs outside the plant, in silky cocoons attached to the leaves.
• Adults active from spring to autumn, with flight peaks varying by region.

6. Monitoring

• Observation of galleries and light streaks on the leaves.
• Inspection of pseudostems to detect perforations and tunnels.
• Pheromone traps for detection and flight tracking.
• Assessment of the percentage of affected plants through direct sampling.

7. Management measures

• Cultural: removal of crop residues, rotation with non-host species and elimination of volunteer plants.
• Preventive: use of insect-proof nets and early installation to prevent oviposition.
• Biological: application of Bacillus thuringiensis on young caterpillars and promotion of natural parasitoids.
• Integrated protection: monitoring with pheromones, definition of intervention thresholds and judicious use of authorised insecticides.

Bibliographic references

• EPPO Global Database – Acrolepiopsis assectella.
• CABI Invasive Species Compendium – Acrolepiopsis assectella.
• Capinera, J. L. (2001). Handbook of Vegetable Pests.
• European Commission IPM Guidelines – Allium crops.