Pulse Beetle
Callosobruchus chinensis
📖 Description
Pulse Beetle is the most serious pest of stored pulses across the Indian subcontinent, attacking green gram, black gram, chickpea, cowpea, lentil, and pigeon pea. Adult females lay eggs glued to the surface of grains. Newly hatched larvae bore directly into the grain, where they feed internally and complete their development, emerging as adults through characteristic round exit holes. Infestation often begins in the field on mature pods and continues in storage, where populations can multiply rapidly, causing 50-60% weight loss within 6 months. The pest causes enormous post-harvest losses of pulses — a critical protein source in the Indian diet — making effective storage management essential for food security.
⚠️ Symptoms to watch for
- Round holes on pulse grains
- eggs glued to grain surface
- webbing and frass in stored grain
- hollowed grains with only husk remaining
- reduced germination
- weight loss up to 50-60% in 6 months of storage
🩹 Treatment
- Solarize infested grains by spreading in thin layer under hot sun for 2-3 days
- mix grains with activated clay 1kg/100kg
- fumigate stored grains with aluminum phosphide
- apply neem oil @ 5ml/kg grain
🌿 Organic treatments
- Solar heat treatment — spread grain in thin layer under sun 2-3 days
- mix with activated clay 1 kg/100 kg grain
- apply neem oil 5 ml/kg grain
- mix with crushed dried leaves of neem or vitex @ 100g/kg
- use hermetic storage (Purdue Improved Cowpea Storage bags)
- freeze grain at -5°C for 4 days
🧪 Chemical treatments
- Fumigate with Aluminum phosphide @ 1 tablet (3g) per tonne grain in air-tight storage
- treat grain with Malathion 5% dust @ 250g/100kg grain
- apply Dichlorvos 76 EC @ 0.5 ml/m3 as space treatment
- Deltramethrin 2.5 EC @ 1 ml/L spray on gunny bags
🛡️ Prevention
- Store only well-dried grains (<10% moisture)
- use hermetic storage bags (PICS)
- clean and disinfect storage structures before loading
- fumigate empty gunny bags
- store pulses in airtight containers
- rotate stored stock (first in first out)
- inspect grains monthly
- use neem-treated gunny bags
🪴 Affected plants
- Stored Pulses (Green Gram, Black Gram, Chickpea, Cowpea, Lentil, Pigeon Pea, Soybean)
- Field Pulses at Maturity
🦋 Natural predators
- Predatory Mites
- Anthocorid Bugs
- Parasitic Wasps (Dinarmus basalis)
- Earwigs
🌱 Host plants
- Vigna radiata
- Vigna mungo
- Cicer arietinum
- Cajanus cajan
- Lens culinaris
- Vigna unguiculata
🔄 Lifecycle
- Female lays 30-100 eggs glued to grain surface.
- Eggs hatch in 4-7 days.
- Larvae feed inside grain for 14-30 days, passing through 4 instars.
- Pupation occurs inside the grain, lasting 4-7 days.
- Adults live 5-15 days.
- Total life cycle 25-40 days; 6-8 overlapping generations per year in warm storage conditions.
📅 Season
- Year-round in storage; field infestation begins at pod maturity Mar-May
🔎 Appearance
- Small oval brownish beetles with white and black markings on the wing covers.
- Larvae are white, grub-like with a brown head, growing up to 5 mm, found inside pulse grains.
💥 Damage level
- High
🔁 Reproduction rate
- Rapid
🗺️ Geographic regions
- Indian Subcontinent
- Southeast Asia
- Africa
- Worldwide Tropics
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