Dalbergia Shoot Borer

📖 Description

The Dalbergia Shoot Borer (Hypsipyla robusta), also called the Mahogany Shoot Borer, is the single most destructive insect pest of Indian rosewood (Dalbergia latifolia — ‘Sheesham’ or ‘Bombay Blackwood’) and sissoo (Dalbergia sissoo) plantations, as well as of introduced mahogany (Swietenia macrophylla) and Indian mahogany (Toona ciliata) plantings. Indian rosewood is one of the world’s most valuable timber species — heartwood fetches ₹3,000–8,000 per cubic foot in the Indian market, and the species is the principal raw material for India’s traditional furniture, musical instrument (sitar, tabla, harmonium), and decorative carving industries. The Dalbergia agroforestry industry of north India (Punjab, Haryana, Uttar Pradesh, Bihar) and the Mahogany plantations of south India (Kerala, Karnataka, Tamil Nadu) collectively support ~500,000 smallholder farm families. Hypsipyla robusta’s economic impact is disproportionate because it attacks the single most valuable part of the tree — the apical meristem (terminal shoot tip) that determines trunk straightness and log grade. A single larva can destroy a year’s apical growth in 5–7 days, and after the larva is gone the tree produces multiple competing vertical shoots (‘candelabra’ form) that never develop into a single straight trunk. The damage is permanent — trees attacked in their first 3–5 years are typically rendered worthless for veneer or sawn timber, even if they survive and grow. The pest is most severe in young plantations (1–5 year age class) when the apical shoot is within the canopy reach of ovipositing females; once trees exceed ~6 m height the pest pressure drops dramatically. The Institute of Forest Genetics and Tree Breeding (IFGTB, Coimbatore) maintains the national Dalbergia improvement programme that includes screening for Hypsipyla resistance — but to date no fully resistant genotypes have been identified, and management relies primarily on cultural control (pruning) and mixed-species planting.