Chestnut weevil

Systematic position: The chestnut weevil (Curculio elephas) is a member of the Coleoptera order and the Curculionidae family. It is a highly specialized pest characterized by a distinctive long rostrum, which the female uses to drill deep into the hard shells of nuts to deposit eggs.

Host plants: This pest primarily targets chestnut trees (Castanea sativa) and various oak species. In commercial orchards, it can cause devastating losses, significantly reducing the yield and quality of the nut harvest, which makes it a critical pest for growers.

Biology and life cycle: The life cycle typically spans one or two years. Adult weevils emerge from the soil in summer, coinciding with the development of the fruit. Females lay eggs inside the developing nuts. The resulting larvae feed exclusively on the kernel, completing their development within the shell. Once mature, larvae exit the nut, drop to the ground, and burrow into the soil to pupate and overwinter.

Nature of damage: Damage is manifested by circular exit holes in the shell. Infested nuts are often hollowed out by larvae, rendering them worthless for food or processing. Additionally, the feeding activity introduces secondary pathogens, causing the internal contents to rot and become covered in mold, which further decreases the market value of the crop.

Control measures: Effective management of the chestnut weevil relies on an integrated approach:

• Rigorous sanitation by collecting and destroying fallen nuts immediately to remove larvae before they enter the soil.
• Cultivation of the soil beneath tree canopies during the pupation period to disrupt the life cycle.
• Monitoring adult population levels with traps to time insecticide applications accurately.
• Applying recommended systemic insecticides when adults are active but before they successfully deposit eggs.