Tree weevil

Systematic position: The genus Orthorhinus belongs to the diverse family Curculionidae (true weevils), classified within the order Coleoptera. These insects are distinguished by their elongated snout, known as a rostrum, which is a specialized tool used for feeding and preparing oviposition sites within the host plant tissue.

Host plants: This pest primarily targets woody perennials and various shrubs. They are commonly observed on species such as eucalyptus and acacia, although they can also infest a range of ornamental and orchard trees. Weakened or stressed trees are particularly susceptible to colonization by these weevils, leading to potential growth stagnation.

Biology and life cycle: The life cycle is largely endophytophagous, meaning the larvae develop within the plant material. The adult female bores into the bark to deposit eggs. Upon hatching, the larvae bore through the sapwood and heartwood, creating extensive galleries that disrupt the vascular tissues of the tree, hindering the transport of water and nutrients.

Damage and pest status: The damage is primarily internal and often goes unnoticed until visible symptoms of decline appear.

• Reduced foliage density and premature leaf drop.
• Dieback of twigs and smaller branches.
• Formation of lesions and entry points for pathogens and wood-rotting fungi.
• Structural instability and increased risk of branch breakage in strong winds.

Control measures: Management strategies focus on sanitation and preventive care. Removing and destroying infested wood is critical to reducing the local population. Systemic insecticides can be applied during the adult flight period to intercept the insects before they reproduce. Maintaining optimal plant health through proper fertilization and irrigation is essential for preventing attacks on vulnerable specimens.