Indian longhorn beetle

Taxonomic classification. The Indian longhorn beetle (Trirachys indutus) is a member of the family Cerambycidae, order Coleoptera. It is recognized as a significant wood-boring insect that poses a notable threat to both forest ecosystems and cultivated fruit orchards within its distribution range.

Host plants. This pest is known for its wide host range, primarily targeting deciduous tree species. Common hosts include various fruit trees like apples and pears, alongside several ornamental trees. The larvae are capable of infesting both weakened and seemingly healthy trees, making them a major concern for arborists and foresters alike.

Biology and life cycle. The life cycle of Trirachys indutus is closely linked to the woody tissues of the host plant. Females deposit eggs into bark crevices or wounds on the tree trunk. Upon hatching, the larvae tunnel into the phloem and cambium layers. As they mature, they penetrate deeper into the sapwood and heartwood, where they feed and eventually form pupal chambers before emerging as adults.

Damage and pest status. The primary damage is caused by larval feeding activity. By tunneling through the tree, larvae disrupt vascular tissues, which impairs nutrient and water transport throughout the tree. Visible symptoms include sawdust-like frass at the base of the tree and exit holes on the trunk. Severe infestations can lead to canopy dieback, crown thinning, and the eventual death of the host plant.

Control measures. Managing this pest is challenging due to the larvae's protected internal lifestyle. An integrated approach is necessary for effective population control:

• Sanitary measures, including the prompt removal and destruction of heavily infested trees to eliminate brood sources.
• Regular inspections of orchards and urban forests to detect early signs of infestation.
• Application of systemic insecticides during the peak flight period of adult beetles to prevent egg-laying.
• Promoting tree vigor through proper irrigation and fertilization to enhance natural resistance to borer attacks.