Acorn weevil

The acorn weevil (Conotrachelus naso) is a beetle belonging to the order Coleoptera and the family Curculionidae. This species is recognized as a significant pest that specializes in damaging the fruit of oak trees. Its morphology, particularly the long snout, is specifically adapted for penetrating the tough pericarp of acorns to feed and deposit eggs.

This insect primarily targets oak acorns, representing a major threat to forest regeneration. The larvae consume the endosperm and embryos of the acorns, rendering the seeds non-viable. In cases of high infestation rates, the acorn crop can be almost entirely destroyed, which significantly hinders the natural expansion and biodiversity of oak woodlands.

The life cycle of the acorn weevil involves several distinct stages. Adult females drill into the developing acorn and oviposit. The larva hatches and feeds inside the nut, completing its development as the acorn matures. Once fully grown, the larva emerges by boring an exit hole, drops to the soil, and burrows deep enough to pupate and overwinter until the next growing season.

Damage is typically identified by small, perfectly circular holes on the surface of fallen acorns. Infested nuts are often light in weight, prematurely drop from the tree, and are highly susceptible to secondary fungal rot. The economic impact is felt mostly in nurseries and forest stands where acorn quality is crucial for seedling production.

Effective management strategies focus on reducing the pest population and protecting the acorn supply:

• Prompt collection and destruction of infested acorns to kill larvae before they exit.
• Tillage of the soil beneath oak trees to expose and kill pupae.
• Monitoring adult activity using specialized traps to determine the timing of interventions.
• Applying biological control agents, such as entomopathogenic nematodes or fungi, to the soil to target the pupal stage.