Ten-spotted leaf beetle

Systematic position: The ten-spotted leaf beetle (Gonioctena decemnotata) belongs to the order Coleoptera and the family Chrysomelidae. It is a specialized pest known for its association with specific host trees, where it can cause significant damage if left unmanaged.

Host plants: The primary hosts for this beetle are members of the willow family (Salicaceae), particularly various willow (Salix) species. Occasionally, the pest may also be found on poplars. These trees are susceptible to infestation in forest nurseries, ornamental gardens, and natural wetlands.

Biology and life cycle: The species undergoes a complete metamorphosis. Adults typically overwinter in the soil or under leaf litter near host plants. In the spring, they emerge, mate, and deposit eggs on the leaves. The larvae go through several developmental stages (instars) before pupating in the soil or amongst debris.

Nature of damage and harmfulness: Both adults and larvae consume foliage. They create irregular holes and can cause complete skeletonization of leaves, leaving only veins behind. This heavy grazing interferes with the tree's ability to perform photosynthesis, leading to stunted growth, reduced vigor, and increased susceptibility to secondary infections.

Protection measures: Effective management of the ten-spotted leaf beetle relies on a combination of cultural and chemical control strategies:

• Monitoring foliage for early signs of egg-laying or larval feeding.
• Removing and destroying infested plant material during the growing season.
• Applying systemic or contact insecticides when larval density exceeds local threshold levels.
• Maintaining healthy tree vigor through proper fertilization and watering to help trees tolerate infestation.