Pine root collar weevil

The pine root collar weevil (Hylobius radicis) is a destructive insect belonging to the order Coleoptera and the family Curculionidae. It is a highly specialized pest that primarily targets young pine trees, making it a major concern in reforestation programs and commercial pine nurseries across its range.

The primary hosts of this beetle are various species of pine, with a particular preference for Scots pine and other susceptible conifers. Young trees aged 2 to 12 years are at the highest risk, as their root systems and stems are still developing and unable to withstand heavy larval feeding, which often leads to tree mortality.

The biological cycle of the pine root collar weevil is complex and typically lasts two years. Adult weevils are nocturnal and feed on the bark of young twigs, but the primary damage is caused by the larval stage. Female weevils lay eggs near the root collar or in soil cracks. Upon hatching, larvae bore into the bark, feeding on the phloem and cambium around the root collar.

Damage is characterized by girdling of the tree trunk at the root collar. As larvae feed, they consume the vital tissues, disrupting the flow of water and nutrients. This results in foliage yellowing, reduced growth, and resinosis at the base of the tree. Eventually, the tree loses structural integrity and dies, often showing a distinct "flagging" effect in the crown.

Effective management strategies require a combination of preventative and corrective actions. Integrated Pest Management (IPM) practices include:

• removing and burning heavily infested trees to reduce the local population;
• avoiding planting susceptible pines in high-risk, recently cleared areas;
• applying registered chemical insecticides to the root collar area during adult activity;
• maintaining healthy stand vigor through proper thinning and site management.