Pea and Bean weevil

Sitona lineatus

Overview:

Sitona lineatus, commonly known as the Pea Leaf Weevil, is a small beetle belonging to the family Curculionidae. As its name suggests, this weevil is a significant pest of leguminous crops, particularly peas and faba beans, and it can cause damage to the foliage by feeding on young leaves.

Detailed Appearance:

  • Adult Pea Leaf Weevils are small, ranging from 3 to 5 millimeters in length.
  • They have an elongated body with a distinct snout characteristic of weevils.
  • Coloration varies but often includes a pattern of dark and light stripes on the elytra (wing covers).

Life Cycle:

  • The life cycle includes egg, larva, pupa, and adult stages.
  • Females lay eggs in the soil near host plants, and larvae hatch and feed on nitrogen-fixing nodules of legumes.
  • Larvae pupate in the soil, and adult weevils emerge.
  • Adults feed on the foliage, creating characteristic notches on leaves.

Identification of Crop Infestation:

  • Presence of adult weevils on the leaves, especially during the growing season.
  • Feeding damage appears as U-shaped notches along the edges of young leaves.
  • Larvae may be found in the soil feeding on nodules.

Management Strategies:

  • Cultural Controls:

    • Rotate crops to disrupt the life cycle and reduce weevil populations.
    • Use early planting to avoid peak weevil activity.

  • Biological Controls:

    • Encourage natural enemies such as parasitoid wasps and predatory beetles.
    • Conservation of natural predators helps regulate weevil populations.

  • Chemical Controls:

    • Apply insecticides labeled for Pea Leaf Weevil control when populations exceed economic thresholds.
    • Focus on the timing of insecticide applications during peak weevil activity.

  • Trap Crops:

    • Plant trap crops to attract adult weevils away from main crops.
    • Monitor and manage weevils on trap crops to prevent migration.

  • Seed Treatment:

    • Use insecticide-treated seeds to protect young plants from early-season weevil damage.
    • Ensure that treated seeds are used according to label instructions.

  • Monitoring:

    • Regularly monitor crops for the presence of adult weevils and feeding damage.
    • Implement thresholds for deciding when control measures are necessary.