Sugarcane root borer

Systematic position: The sugarcane root borer (Polyocha depressella) belongs to the order Lepidoptera and the family Pyralidae. It is a significant pest of sugarcane crops, primarily distributed across regions like India and neighboring countries, where it causes substantial yield losses.

Crops and economic impact: The pest targets sugarcane, specifically attacking the stalks of young plants. By boring into the base of the stem, the larvae destroy the growing point. This damage significantly reduces sugar content, biomass, and overall plantation yield, making it a priority pest for sugarcane growers.

Biology and life cycle: The insect undergoes complete metamorphosis consisting of egg, larva, pupa, and adult stages. Females typically deposit eggs on leaf sheaths or near the soil surface. After hatching, the larvae immediately tunnel into the stalk. Multiple generations per year allow the population to persist throughout the growing season.

Nature of damage: The primary symptom is the 'dead heart' phenomenon, where the central leaf whorl withers and dies. Infested stalks exhibit internal tunnels filled with larval frass. Weakened plants often develop side tillers, but these are generally unproductive, leading to uneven field stands and poor quality of the raw material.

Protection measures: Integrated Pest Management (IPM) is essential for effective control:

• Cultural practices such as removing crop residues immediately after harvest to disrupt the life cycle.
• Use of Trichogramma species as a biological control agent for egg parasitism.
• Monitoring adult population levels with light or pheromone traps.
• Application of granular or systemic insecticides at the soil level during critical stages of crop growth.
• Promoting strong plant vigor through balanced fertilization and adequate irrigation.