Cardamom Root Grub
Leucopholis burmeisteri
Soil Pests & Nematodes High Risk 25–30 mm (mature larva); 20–25 mm (adult beetle)
📖 Description
Leucopholis burmeisteri is the most important white grub pest of cardamom in India. The species is endemic to the Western Ghats cardamom tract of Kerala (Idukki, Palakkad), Tamil Nadu (Cardamom Hills), and Karnataka (Coorg). Indian small cardamom production is approximately 22,000 tonnes from 70,000 ha — India is the second-largest producer after Guatemala. Root grub infestations can destroy 15–30 % of clumps in established plantations, and entire plantings can be lost in newly cleared forest-edge sites. The beetle has a 2-year lifecycle — adults emerge synchronously in April–June after the first pre-monsoon showers, mate, and oviposit in soil near cardamom clumps. Larvae feed on roots for 18–20 months before pupating.
⚠️ Symptoms to watch for
- Plants show gradual yellowing of leaves starting from the older foliage; tillers become stunted and fail to produce new shoots; panicles are short and produce few capsules; in severe infestations entire clumps wilt and can be pulled easily from the soil because the root system is destroyed; inspection of soil around affected clumps reveals curled white grubs feeding on roots.
🩹 Treatment
- Apply carbofuran 3 G at 10 g per clump or phorate 10 G at 15 g per clump around the root zone during the pre-monsoon shower (April–May) and again after the northeast monsoon (November). Drench chlorpyriphos 20 EC at 2.5 ml/L around the base of affected clumps. Use entomopathogenic nematodes (Heterorhabditis indica) at 1 billion IJ/ha through soil drench for organic management.
🌿 Organic treatments
- Apply Metarhizium anisopliae (1×10^9 CFU/g) at 5 kg/ha mixed with farmyard manure around the root zone during pre-monsoon showers. Apply Heterorhabditis indica nematodes at 1 billion IJ/ha. Use neem cake at 250 g per clump as a soil amendment. Collect and kill adult beetles at dusk during their flight period (April–June) using light traps (1/ha).
🧪 Chemical treatments
- Carbofuran 3 G (10 g/clump), phorate 10 G (15 g/clump), or chlorpyriphos 20 EC (2.5 ml/L soil drench). Apply during pre-monsoon showers for best efficacy. Repeat after 4 months if pest pressure persists.
🛡️ Prevention
- Avoid planting cardamom in freshly cleared forest land where scarab populations are naturally high. Plough and fallow land for one season before planting to expose grubs to birds. Maintain balanced nutrition — potassium-deficient plants are more susceptible. Rotate with non-host crops (rice, fallow) where possible.
🪴 Affected plants
- Cardamom (Elettaria cardamomum) is the primary host; larvae also feed on roots of small cardamom, large cardamom (Amomum subulatum), ginger, turmeric, banana, coffee, and pepper in mixed Western Ghats plantings.
🦋 Natural predators
- Birds (crows, mynas, drongos) consume adults and exposed larvae. Entomopathogenic fungi (Metarhizium anisopliae, Beauveria bassiana) and nematodes (Heterorhabditis indica) provide natural regulation in moist forest soils. Predatory ground beetles (Carabidae) feed on eggs and young larvae.
🌱 Host plants
- Elettaria cardamomum (small cardamom — primary host), Amomum subulatum (large cardamom — Sikkim, Darjeeling), Zingiber officinale (ginger), Curcuma longa (turmeric), Musa spp. (banana), Coffea spp. (coffee), Piper nigrum (pepper) in mixed Western Ghats plantings.
🔄 Lifecycle
- Egg (15–20 days, in soil 5–10 cm deep) → Larva (18–20 months, three instars, root-feeding) → Pupa (20–30 days, in soil cell) → Adult (30–60 days, April–June emergence).
- Semivoltine — one generation every 2 years.
📅 Season
- Adult emergence and flight: April–June (pre-monsoon showers).
- Oviposition: May–July.
- Larval feeding: continuous for 18–20 months.
- Pupation: March–April of the second year.
🔎 Appearance
- Adult beetles are broad, oval, dark reddish-brown scarabaeids with a velvety appearance due to dense short yellowish-grey scales on the elytra; the head is small and partly concealed beneath the pronotum; legs are strong and fossorial.
- Larvae are typical C-shaped white grubs with a brown head capsule, three pairs of thoracic legs, and a swollen bluish-grey posterior; mature larvae reach 30 mm.
💥 Damage level
- Severe
🔁 Reproduction rate
- Slow
🗺️ Geographic regions
- Western Ghats cardamom tract of India (Kerala — Idukki
- Palakkad
- Wayanad; Tamil Nadu — Cardamom Hills
- Theni; Karnataka — Kodagu
- Hassan). Also reported from Sri Lanka.
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