Violet seed weevil

Systematic position. The violet seed weevil (lat. Apion violaceum) belongs to the order Coleoptera and the family Apionidae. It is a small snout beetle primarily recognized for its deep violet coloration and its specific preference for plants within the Polygonaceae family.

Host plants and damage. The primary hosts for this pest include garden sorrel and rhubarb. Adult beetles feed on leaves, creating small circular holes, while the larvae are internal feeders. The larvae tunnel into the stems and flowering stalks, which severely stunts the plant's growth and diminishes the yield and quality of the crop.

Biology and life cycle. Adults overwinter in leaf litter, debris, or the top layer of soil. In spring, as temperatures rise, they emerge to feed on fresh growth. Females deposit eggs into the stems or petioles of the host plant. The larvae hatch and complete their development inside the plant tissues, eventually pupating within the stem before emerging as new adults.

Damage symptoms. The most obvious sign of an infestation is the presence of numerous small holes on the foliage, often referred to as shot-hole damage. As larvae feed internally, the affected stalks may weaken, become chlorotic, or fail to produce viable seeds. In severe cases, the entire plant architecture may be compromised due to internal tissue necrosis.

Control measures. Effective management starts with good sanitation practices, such as clearing plant debris after the harvest to eliminate overwintering sites. Cultural methods include regular soil cultivation to disrupt the life cycle. In commercial operations, insecticides are applied if the threshold of leaf damage is exceeded. Key methods include:

• Removing and destroying infested plant stalks.
• Practicing crop rotation away from Polygonaceae.
• Applying systemic insecticides during the peak of adult activity.
• Using soil cultivation to expose pupae to natural enemies.