Large chestnut weevil

Systematic position. The large chestnut weevil (Curculio proboscidens) belongs to the order Coleoptera and the family Curculionidae. This species is highly specialized, specifically adapted to feed on and breed within the nuts of trees in the genus Castanea.

Affected crops. This pest primarily targets chestnut trees, particularly the American chestnut and the Chinese chestnut. It represents a significant threat to nut production, as infestations can result in the loss of a major portion of the annual yield.

Biology and life cycle. The adult weevil possesses an exceptionally long snout, which the female uses to drill into developing chestnuts to deposit her eggs. Once the eggs hatch, the larvae feed on the developing nut meat. Upon reaching maturity, the larvae emerge from the nut, drop to the ground, and burrow into the soil to pupate and overwinter.

Damage and economic impact. The primary economic impact occurs during the larval stage. Larvae hollow out the nut, rendering it inedible and unsalable. The exit holes created by the mature larvae are the most visible sign of infestation, often appearing after the harvest, which complicates quality control and storage.

• Daily harvesting and destruction of fallen nuts to break the weevil's life cycle.
• Application of targeted insecticide sprays timed with adult emergence before oviposition occurs.
• Maintaining clean orchard floors to reduce overwintering sites for the larvae.
• Soil cultivation around the base of the trees to disturb and kill pupating larvae in the ground.