Banana Rhizome Weevil
Cosmopolites sordidus
📖 Description
Banana Rhizome Weevil (Banana Weevil Borer) is the most important pest of banana across the Indian subcontinent, particularly damaging to plantations in Tamil Nadu, Kerala, Karnataka, Andhra Pradesh, Maharashtra, and Gujarat. Adult female weevils lay eggs in cavities chewed into the rhizome or lower pseudostem. Newly hatched larvae tunnel extensively through the rhizome, weakening the plant, reducing nutrient uptake, and causing yellowing, wilting, stunting, and plant breakage. Tissue culture plants and healthy certified suckers are essential for new plantings, as the pest is primarily spread through infested planting material. The pest is most damaging in ratoon crops and poorly managed plantations where old rhizomes accumulate. Integrated management with pest-free planting material, biological control with entomopathogenic fungi, pseudostem trapping, and crop rotation is essential.
⚠️ Symptoms to watch for
- Yellowing and wilting of leaves, stunted plants, tunneled and weakened rhizomes with frass, snapping of plants at soil level in heavy infestation, reduced bunch size, plant death in severe cases, yield loss 30-80%
🩹 Treatment
- Use healthy, pest-free suckers and tissue culture plants, apply Beauveria bassiana @ 5g/L in soil, set up pseudostem traps @ 25/ha for adult monitoring, drench soil with chlorpyrifos, practice crop rotation
🌿 Organic treatments
- Use healthy pest-free suckers or tissue culture plants, apply Beauveria bassiana @ 5 g/L in soil around rhizome, set up pseudostem traps @ 25/ha (split lengthwise, place near plants, collect and kill adults), apply neem cake @ 250 g/plant, apply Metarhizium anisopliae in soil, practice crop rotation with non-hosts, parboil suckers in hot water (55°C for 20 min) before planting
🧪 Chemical treatments
- Drench soil with Chlorpyrifos 20 EC @ 5 ml/L per plant, apply Carbofuran 3G @ 25 g per plant in soil, Fipronil 5 SC @ 2 ml/L drench, Phorate 10 G @ 25 g per plant in soil, spray Quinalphos 25 EC @ 1 ml/L on pseudostem base
🛡️ Prevention
- Use certified pest-free suckers or tissue culture plants, inspect suckers thoroughly before planting, parboil suckers in hot water (55°C for 20 min), practice crop rotation with non-host crops (rice, legumes), destroy infested plants, remove and burn crop residues after harvest, use pseudostem traps for monitoring, avoid planting in infested soil for at least one season, maintain field sanitation
🪴 Affected plants
- Banana, Plantain, Other Musa Species
🦋 Natural predators
- Predatory Beetles (Platysoma), Ants, Spiders, Earwigs, Entomopathogenic Fungi
🌱 Host plants
- Musa spp. (banana, plantain)
🔄 Lifecycle
- Female lays 50-200 eggs singly in cavities chewed into the rhizome.
- Eggs hatch in 5-8 days.
- Larvae tunnel through the rhizome for 14-25 days, passing through 5-8 instars.
- Pupation occurs in a pupal cell in the rhizome, lasting 6-10 days.
- Adults live 4-12 months and are nocturnal.
- Total life cycle 30-45 days; 4-8 generations per year.
📅 Season
- Year-round in tropical climates, peaks during warm humid periods (Apr-Nov)
🔎 Appearance
- Small, hard, dark brown to black weevils with a long curved snout and mottled appearance from yellowish scales on the wing covers.
- Adults play dead when disturbed.
- Larvae are creamy-white, legless grubs with a brown head, growing up to 12 mm, found tunneling in the rhizome.
💥 Damage level
- High
🔁 Reproduction rate
- Moderate
🗺️ Geographic regions
- Indian Subcontinent
- Worldwide Banana-Growing Regions
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