Hazelnut weevil

Systematic position: The hazelnut weevil (Triotemnus coryli) belongs to the order Coleoptera and the family Curculionidae. It is a highly specialized insect pest that targets hazelnut trees, making it a primary concern for nut growers in regions where hazelnut production is significant.

Affected crops: The primary host plant for this pest is the hazel (Corylus), specifically cultivated hazelnut varieties. While it primarily focuses on these species, intense infestations can occur in mixed-variety orchards, significantly impacting the yield and quality of the final product.

Biology and lifecycle: The lifecycle of Triotemnus coryli is tightly linked to the phenological development of the hazelnut. Adult weevils emerge from the soil in spring. After feeding on leaves, the female deposits eggs into developing nutlets. The larva then bores into the kernel, consuming it throughout its developmental stage before returning to the ground to pupate.

Damage and economic impact: The larvae cause severe damage by consuming the kernel, which is the commercially valuable part of the nut. Infested nuts often drop prematurely or become hollow, rendering them unfit for sale or consumption. In cases of high pest pressure, the damage can jeopardize a major portion of the annual yield.

Control measures: Management requires an integrated strategy to reduce population numbers over time.

• Mechanical control by removing and destroying fallen infested nuts to prevent larvae from burrowing into the soil.
• Tillage of soil beneath trees to disrupt the pupation process.
• Application of selective insecticides during the adult emergence phase to prevent egg-laying.
• Monitoring using pheromone or visual traps to time insecticide applications accurately.