Pea leaf weevil

Sitona lineatus

1. Identification

• Common name: Pea leaf weevil
• Scientific name: Sitona lineatus L.
• Order: Coleoptera
• Family: Curculionidae

2. Pest description

• Adults: Weevils of 4–5 mm; greyish to light brown body with darker longitudinal stripes; short rostrum; geniculate antennae typical of weevils.
• Larvae: Legless, whitish, curved body, brown head; develop in the soil feeding on roots and nodules.
• Pupae: Formed in the soil, in small earthen chambers.

3. Main hosts

• Legumes, especially pea and broad bean.
• May also occur in other cultivated or spontaneous Fabaceae.

4. Symptoms and damage

• Leaves with semicircular notches on the margins, caused by the adults.
• Root damage caused by the larvae, which feed on roots and nitrogen-fixing nodules.
• Reduction in nitrogen-fixing capacity and decrease in plant vigour.
• Possible impact on yield, especially in early or intense infestations.

5. Biological cycle

• One generation per year in most regions.
• Adults emerge in spring and feed on young leaves.
• Egg-laying in the soil; larvae develop feeding on roots and nodules.
• Pupation in the soil; adults overwinter and resume activity the following spring.
• Development favoured by mild springs and the continuous presence of legumes.

6. Monitoring

• Observation of semicircular notches on the leaf margins.
• Inspection of young plants, especially in the first weeks after emergence.
• Assessment of root damage on suspect plants.
• Reinforced monitoring in plots with a history of the pest.
• Use of pheromone traps for early detection of adults and population density.

7. Management measures

• Cultural: Crop rotation avoiding consecutive legumes; sowing under conditions that favour rapid emergence; elimination of spontaneous legumes.
• Preventive: Choice of more tolerant varieties; improvement of soil fertility to reduce the impact of root damage.
• Integrated protection: Intervention only when population levels justify it; preference for selective methods compatible with beneficial organisms; regular monitoring in the early stages of the crop.

Bibliographic references

• CABI Invasive Species Compendium – Sitona lineatus.
• EPPO Global Database – Sitona lineatus.
• Williams, L. et al. (1995). Biology and management of Sitona species in legume crops.
• Parker, W. E. (1990). The pea leaf weevil: ecology and crop impact.